Paediatric Respiratory Reviews 17 (2016) 80–87
Contents lists available at ScienceDirect
Paediatric Respiratory Reviews
Review
Evaluation of upper airway obstruction in infants with Pierre Robin sequence and the role of polysomnography – Review of current evidence Vudum Sridhar Reddy 1,2,* 1 2
Neonatal Emergency Transport Service, Sydney Children’s Hospitals Network, Westmead, Sydney, NSW 2145, Australia School of Medicine and Public Health, University of Newcastle, Callaghan, Newcastle, NSW 2308, Australia
EDUCATIONAL AIMS To enable the reader to know objective methods of assessment of upper airway obstruction in infants with Pierre Robin sequence to understand the current evidence regarding the role of polysomnography in the management of PRS infants to develop a plan for investigation of upper airway obstruction in PRS infants
A R T I C L E I N F O
S U M M A R Y
Keywords: Pierre Robin sequence Polysomnography Oximetry Upper airway obstruction
Pierre Robin sequence (PRS) is a heterogeneous condition presenting with upper airway obstruction (UAO) of varying severity. Polysomnography (PSG) is an objective investigation to assess the severity of obstructive sleep apnea and UAO. Its role in the management of PRS has not been well defined. This review summarizes the available evidence on the role of PSG in the assessment of infants with PRS in the context of other commonly used methods of assessment. ß 2015 Elsevier Ltd. All rights reserved.
INTRODUCTION Pierre Robin sequence (PRS) is the association of micrognathia, glossoptosis and upper airway (UAO) obstruction with or without cleft palate [1–3]. Cleft palate is considered by some as an essential component [4–8]. PRS is causally heterogeneous and phenotypically
* Neonatal Emergency Transport Service, Hawkesbury road, Westmead, NSW 2145. Tel.: +61404541904/61296338700; fax: +61296338782. E-mail address: [email protected]. Abbreviations: AHI, Apnea and hypopnea index: Number of apneas and hypopneas per hour; CAI, Central apnea index; JI, Jaw index; MAI, Mixed apnea index; MDO, Mandibular distraction osteogenesis; MMD, Maxillo-mandibular discrepancy; NPA, Nasopharyngeal airway; OAI, Obstructive apnea index; OAHI, Obstructive apnea hypopnea index: AHI after excluding central apneas; ODI, Oxygen desaturation index: Number of desaturation episodes of > 3% per hour; OMAHI, Obstructive and mixed apnea hypopnea index: same as OAHI; ORDI, Obstructive respiratory disturbance index: same as OAHI; PSG, polysomnography; RDI, Respiratory disturbance index: AHI + RERAs; RERA, Respiratory event related arousals: respiratory events associated with arousals that cannot be classified as apnea or hypopnea; TcO2, Transcutaneous oxygen level; TcCo2, Transcutaneous carbon dioxide level; TLA, Tongue lip adhesion; UAO, Upper airway obstruction. http://dx.doi.org/10.1016/j.prrv.2015.10.001 1526-0542/ß 2015 Elsevier Ltd. All rights reserved.
variable [9]. It is associated with a cleft palate in up to 90% of cases [10,11]. About 50% of PRS cases have additional syndrome, anomaly or chromosomal abnormality (often called syndromic PRS) [4,12,13]. Accurate diagnosis of syndromic PRS is important, as it is associated with worse airway and feeding problems as well as higher mortality and psychomotor retardation [14]. UAO in PRS is primarily due to glossoptosis caused by mandibular hypoplasia. In addition, it may also be due to narrowing of oropharynx caused by collapse of pharyngeal walls [15] and structural abnormalities of larynx and subglottic airway [16,17]. Nonsurgical methods have been reported to be adequate to manage UAO in 40.3% to 84% cases of PRS [18–22]. UAO is associated with feeding problems and growth failure in PRS infants. However, feeding problems may also be due to primary swallowing dysfunction due to oroesophageal motor disorders [23–25]. Objective methods to assess the severity of UAO are essential to target the treatment to the severity of the condition. PSG is a gold standard investigation for detection and quantification of obstructive sleep apnea (OSA) [26]. PSG involves recordings using multiple channels to acquire information regarding sleep states, nasal and
V.S. Reddy / Paediatric Respiratory Reviews 17 (2016) 80–87 Table 1 Channels and sensors used to acquire PSG data [27] Channel/signal
Sensor
EEG ECG EOG
Central C1 and C2 Occipital O1 and O2 electrodes Chest leads Electrodes lateral to the outer canthus vertical electrodes Submental electrodes Thermistor, nasal pressure transducer, end tidal CO2 Inductance plethysmography bands or piezoelectric crystal bands
EMG Nasal/oral airflow Respiratory motion from ribcage and abdomen Oxygen saturation Body movements Sleep position Arterial CO2
Pulse oximetry EMG on legs/arms or accelerometer/actimeter device on the foot Position sensor on back of diaper End tidal CO2 or transcutaneous CO2
EEG, Electroencephalogram; EOG, Electro-occulogram; EMG, Electromyogram; ECG, Electrocardiogram.
oral airflow, respiratory effort, oxygen saturation and CO2 levels (Table 1) during an overnight sleep. The current standard of scoring and reporting PSG events is based on American Academy of Sleep Medicine (AASM) criteria [27] (Table 2). Its role in the management of PRS infants has not been clearly defined. The aim of this review is to evaluate the role of PSG in the context of other commonly used methods for assessment of UAO in these infants.
METHODS Databases MEDLINE, EMBASE, CINAHL were searched with the search strategy [Pierre Robin Syndrome or Pierre Robin Sequence] AND [polysomnography or sleep study or oximetry or oxygen saturation or saturation monitoring or obstructive sleep apnoea or nasopharyngoscopy or laryngoscopy or bronchoscopy] without restriction on study design. Manual search of the reference lists were done to find relevant articles. Studies that used PSG in PRS subjects under 3 months age were included. Information relating to the use of clinical methods, oximetry, laryngoscopy/bronchoscopy and PSG was extracted from the articles.
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Clinical assessment of upper airway obstruction A number of different methods have been used to assess UAO in infants with PRS (Table 3). The most common method of assessment of UAO in PRS infants is beside clinical assessment. A structured method of recording signs of UAO (Table 3) while the infant is lowered during sleep from upright position into supine position has been described [29,30]. If no signs of respiratory distress occurred during this manoeuvre, it is repeated while the infant is sucking a bottle. Maxillo-mandibular discrepancy and Jaw index Objective measures of micrognathia include maxillo-mandibular discrepancy (MMD) and jaw index (JI). MMD is the distance between the maxillary and mandibular alveolar ridges in the midline. MMD 3 mm is considered significant in a newborn [31,32]. This is best measured with infant held in upright position with the mandible approximated to the maxilla passively. Schaefer et al [32] reported a MMD of 3-9 mm in PRS infants who required only prone positioning and 8-10 mm in those treated with TLA in the first month of life. Nasopharyngeal airways (NPA) were not used in their study. MMD normalised due to natural growth of the jaw over the first year of life in these patients. Similarly, JI (distance between the alveolar ridges x maxillary arch/mandibular arch in mm) is a bedside measurement, which can be monitored over time [3,33]. The JI is 4.2 1.8 in normal infants. A JI >10 in a newborn is associated with respiratory and feeding difficulties [3,34]. Bijnen et al reported a JI of 6.5 to 17.2 in infants who underwent TLA in their series [34]. Oximetry
The search revealed 100 articles in English of which 20 original studies reported the use of PSG in PRS infants. The majority of the studies were retrospective case series. There was one small RCT evaluating the effect of an oral appliance in infants with PRS that reported mixed and obstructive apnea index as an outcome measure [28]. Since it was not possible to statistically combine the data from these studies a descriptive review is presented here.
Wagener et al [30], Glynn et al [21] and Schaefer et al [32] reported the use of continuous oxygen saturation monitoring to assess the severity of UAO. A trend analysis showing >5% of total time (24 – 36 hours) spent with saturation 3% desaturation
Clinical assessment Tracheal tug; suprasternal, intercostal and subcostal recessions Audible stridor or stertor Intolerance of supine position Oxygen desaturation in supine and/or prone position Feeding difficulty and/or oxygen desaturation during feeding Maxillo-mandibular discrepancy Jaw index Investigations Oximetry Polysomnography Flexible nasopharyngoscopy and bronchoscopy Cephalometry
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Nasopharyngoscopy and bronchoscopy Fibre optic nasopharyngoscopy/bronchoscopy is performed in PRS infants to confirm the site of airway obstruction at the tongue base [37–39] and to diagnose additional anatomical problems. Treatment strategies such a prone positioning, NPA, TLA and mandibular distraction osteogenesis (MDO) are aimed at relief of tongue-base obstruction. Presence of additional anatomical problems will make these interventions less effective [31,32]. Hence, fibreoptic endoscopy is mandatory prior to undertaking surgical procedures for airway management. Problems identified at fibre optic endoscopy include choanal atresia, laryngomalacia, bronchomalacia, tracheomalacia, bronchial stenosis, tracheal stenosis (complete tracheal rings), and subglottic stenosis [16,17,40,41] Fibre optic endoscopy has also been used to position the NPA accurately just superior to the epiglottis [21,37,42]. Bravo et al [43] (2005) compared videonasopharyngoscopy with PSG to predict OSA (defined as ORDI of 5) in PRS children (1month to 4 years age) and reported a sensitivity and specificity of 87% and 100% and positive predictive value and negative predictive values of 100% and 84% respectively. They suggested that videonasopharyngoscopy could be an alternative to PSG to assess the severity of UAO. Polysomnography Early studies of PSG in PRS infants (Table 4) [28,39,40,43–56] demonstrated the use of limited PSG to document severity of UAO, which improved the confidence of carers in decision-making regarding the need for TLA. Freed et al [48] used the information from limited PSG (9 channels) along with TcO2, TcCO2 and oxygen saturation to derive objective criteria for performing TLA. Gilhooly et al [47] used 4-channel PSG to determine the need for TLA and to demonstrate the procedure’s success. Early discharge was facilitated by documentation of absence of significant UAO on PSG. PSG was used during follow up to document resolution of UAO in their patients. Bull et al [46] used limited PSG to document apneas (lasting 15 sec or associated with SpO2 < 90%) and the time spent at different levels of oxygen saturation and end tidal CO2. PSG information was integrated with clinical judgement to guide the nature of airway interventions. A number of studies used PSG to show improvement of measures of OSA after a surgical intervention [34,39,44,45,49,57– 60]. However, few have reported the technique and scoring methods used for PSG and many were performed prior to the publication of AASM criteria. Several authors have reported performing PSG as part of preoperative work up to rule out central apneas, as surgical interventions such as MDO and TLA are unlikely to be successful if central apnoeas predominate [61]. Different cut-offs and more than one index were used to define and grade OSA [eg. AI >5 by Monasterio et al. [51]; ORDI > 5 Bravo et al [43]; OAHI >1 Anderson et al. [55]; AHI >1 Daniel et al. [52]; MOAI >3 Buchenau et al. [28]; and OMAHI >3 MacLean et al [56]]. Studies that correlate the severity of OSA by its metrics with the type of intervention are lacking. Daniel et al [52] graded OSA in PRS infants based on AHI into mild (1-5) moderate (>5-10) and severe (>10). There were 10 mild-moderate and 29 severe cases. Eight mild-moderate and 4 severe cases that required prone position alone for airway management had a mean AHI of 28.9 and a mean OAHI of 22.5. Among the 27 PRS infants who required airway intervention (CPAP alone in 22 and MDO in 5) the mean AHI and mean OAHI were 39 and 30.6 respectively. The severity of OSA in patients undergoing surgical procedures such as MDO or TLA in the studies varied widely from a mean AHI of 6.4 to a mean OAHI of 52.6 (Table 5) suggesting that there is a great variation of practice
in the use of surgical methods in PRS infants [39,40,44,45,49– 51,60,62]. Two cross sectional studies provided PSG data on the severity of OSA in PRS infants using the AASM scoring system. In the first of these studies [55], 13 infants (7 – 214 days age) out of 33 underwent standard 16-channel PSG. OAHI ranged from 0 to 85.7 (mean 33.5; median 9). OSA was diagnosed in 11/13; mild in two (OAHI >1- 3 occurred in all infants with PRS (n=8) and 69% of infants with isolated cleft palate. PRS infants had a higher OMAHI (34.3 5.1) compared with isolated cleft palate infants (7.61.2). Infants who were recommended for intervention (CPAP, Oxygen, MDO) and follow up had an AHI of 31.420 compared with AHI of 11.9 6.4 in those who were advised no intervention [56]. Chang et al [63] reported use of PSG to confirm the resolution of desaturation and obstruction episodes before discontinuing NPA in PRS patients. Wilson et al [64] presented a case series of seven PRS infants in whom PSG was used to document severity of UAO at admission and to confirm its resolution prior to discharge, and during follow up of patients with symptoms such as obstructed breathing or poor weight gain. PSG indices were not reported in these studies. DISCUSSION The purpose of this review was to evaluate the current evidence for the role of PSG in assessing UAO in PRS infants. Most of the literature on this topic consists of retrospective case series. The majority of the studies that included PSG used it to show improvement of one or more measures of OSA after surgery. Details regarding the conduct of PSG or scoring of respiratory events were either incomplete or not provided in the majority of these reports. In the studies that provided the details, methods of performing PSG and the scoring of events varied greatly. Several studies did not provide definitions for the indices used to quantify OSA. The standard definition of OSA in infants and children is AHI > 1 [65,66]. However, this definition does not take into account age related changes in respiratory events in infants in whom obstructive and central apneas decrease with increasing age [67]. Data on normal values for PSG indices in infants is available from studies performed before AASM criteria were published. In those studies, [67] (apnoea defined as cessation of airflow for 3 sec) 90th percentile for obstructive apnea index (OAI) ranged from 0.6 to 0.7 after 2 weeks of age which decreased to 0.2 to 0.4 by 2-3 months of age. Similarly the 90th percentile values for mixed apnoea index (MAI) were 0.3 to 0.5 after 2 weeks of age, decreasing to 0.2 to 0.4 by 2-3 months of age. The 95th percentile for central apnoea index (CAI) was 22 to 45 in 1-3 month age group. So, the combined OAI and MAI is around 1 at 90th centile in normal infants. This estimate does not include hypopnoeas, which are included in the calculation of OAHI and AHI, nor does it include central apnoeas, which are included in AHI. It is not clearly established as to what constitutes pathologically significant OSA in infants. Some authors have used a higher level (>3) of OAHI to define OSA in infants [56]. In the context of PRS, OSA associated with desaturation episodes and/or feeding problems can be considered significant. However feeding problems in PRS infant may also be intrinsic [23,25]. Detection of OSA (as per current definition) in a PRS infant may not need a change of management if the infant is stable in prone position and thriving on oral feeds or nasogastric feeds. Expressing the severity of OSA in terms of OAHI is more meaningful
Table 4 Studies reporting the use of PSG in the assessment of PRS infants Study description
Cases
Age at assessment
Type of PSG used
Scoring methods and PSG indices reported
Definition of OSA and grading
Results, study conclusions, comments
Freed et al., 1988 [48]
Retrospective case series
6 infants in a neonatal unit
1 - 54 days
Scoring of events not defined
Not defined
Bull et al., 1990 [46]
Retrospective, case series
21 infants in a neonatal unit
1 – 8 weeks
nasal/oral thermistor, ETCO2, ECG, SpO2, tachograph thoracic/abdominal strain gauge, diaphragmatic EMG cardiotachometer, SpO2, ETCO2, nasal and oral thermistor, thoracic/ abdominal strain gauge
Apnea significant if lasting 15sec or associated with SpO2 < 90%.
Gilhooly et al., 1993 [47]
Retrospective, case series
13 infants in a neonatal unit
Newborn infants
ECG, abdominal strain gauge or thoracic impedance, ETCO2, SpO2
Scoring of events not defined. % sleep time SpO2 < 90 and < 85; % sleep time ETCO2 > 45; % sleep time obstructive apnoea > 6 sec. Scoring of events not defined
Renault et al., 2000 [53]
Retrospective, case series
24 IPRS infants
Birth – 2 mo
Comprehensive PSG. Daytime nap studies between feeds in supine position
Monasterio et al., 2004 [51]
Clinical series evaluating the effect of MDO
8 – 150 days
Not mentioned
Bravo et al., 2005 [43]
Prospective study comparing videonasopharygoscopy and PSG Retrospective, case series
18 infants who failed prone position 52 PRS children with SDB symptoms 13 infants
4 infants underwent TLA. Objective criteria for TLA were provided based on TcO2, TcCO2, obstructive episodes on PSG and oxygen saturation 18 infants had obstructive apnoea. Based on severity of obstruction patients received TLA or home monitoring with or without oxygen. Grading of severity of obstructive apnoea not defined. 6(46%) had significant UAO and were recommended TLA. Grading of severity of obstructive apnoea not defined. Use of PSG avoids prolonged observation in hospital Number of OMAs 1.8 - 124 per 100 min. OMAs occurred in 19/20 infants with no signs of respiratory distress. OMAs incidence higher in infants with feeding problems and respiratory distress Mean AI 18.3, HI 8.5 before surgery. No episodes of apnoea or hypopnoea occurred after MDO
1mo – 4yr
Comprehensive PSG.
Mean 48 (7 - 214) days
Standard overnight 16 channel PSG
2.72.3 (0.1 – 8.9) mo
Standard PSG.
AASM scoring criteria. AHI OMAHI (Obstructive -mixed apnoea hypopnoea index)
OMAHI of > 3
5 – 141 days?
Standard PSG
AHI 1-5 mild >5-10 moderate >10 severe AHI= number of central and obstructive apneas and hypopneas per hour
8 infants who had TLA
Mean 23 (10 -54) days
Standard 16 channel PSG
Respiratory event significant if lasting > 2 respiratory cycle duration and associated with arousal or >3% desaturation. Apnea is decrease in airflow to 10 severe. No grading applied
V.S. Reddy / Paediatric Respiratory Reviews 17 (2016) 80–87
Author, year
Mean preop OAHI 52.6 (7.1 – 85.7); Postop OAHI 10.3 in seven infants showing improvement. OAHI improved from 39.7 (4.5 – 177) to 5.8 (0- 34)
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0 - 60 days, Median 3 days
0-60 days, Median 5 days
11 infants
15 infants
Components of standard EEG excluding EEG, EOG, EMG
Multichannel PSG 5-99 days 24 in MDO group 15 in TLA group
Components of standard PSG without EEG
Standard PSG? No info on performance 11-310 days 13 infants
Buchenau et al., 2007 [28] Bacher et al., 2011 [54]
Flores et al., 2014 [39]
Looby et al., 2009 [49]
Cross over RCT of pre-epiglottic baton plate case series on efficacy of pre-epiglottic baton plate
Standard PSG 5 days to 6 years 67 infants Genecov et al., 2009 [50]
case series to demonstrate efficacy of MDO Large case series to evaluate efficacy of MDO case series to demonstrate efficacy of MDO Retrospective case series comparing outcomes of MDO and TLA Cheng et al., 2011 [40]
ORDI, Obstructive respiratory distress index; OA, obstructive apnoea; MA, mixed apnoea; AASM, Americal academy of sleep medicine.; AHI, apnoea hypopnoea index. CAI, central apnea index; MOAI, mixed and obstructive apnea index; OAHI, obstructive apnoea hypopnoea index; ODI, oxygen desaturation index.; RDI, respiratory disturbance index. HR, heart rate; ETCO2, end tidal CO2; TcO2, transcutaneous oxygen. TcCO2, transcutaneous carbondioxide; SDB, sleep disordered breathing.
MOAI > 3
Mean MOAI decreased from 13.8 to 3.9 with the device MOAI > 3
Preop mean AHI in MDO group 47 and in TLA group 37.6. At 1 month postop mean AHI 10.9 and 21.6 respectively. At 1 year postop 2.5 and 22.1 respectively none
none
Mean AHI decreased from 10.57(0 -43) to 2.21(0-12.9) after MDO
Preoperative RDI 35 – 50; postoperative RDI 5- 15
Preoperative RDI 3.3 to 45.8 and postoperative RDI 2.2 to 13.6 none
Scoring method not mentioned RDI Scoring method not mentioned RDI Scoring method not mentioned AHI Scoring method not mentioned. AHI. Apnea defined as a cessation of breathing for a duration of 10 sec Scoring as per American Thoracic society 1996. MOAI, CAI, ODI Scoring as per American Thoracic society 1996. MOAI, CAI, ODI Standard PSG 6 infants
Results, study conclusions, comments Definition of OSA and grading Scoring methods and PSG indices reported Type of PSG used Age at assessment Cases Study description Author, year
Table 4 (Continued )
Mean MOAI decreased from 17.2 at admission to 3.8 at discharge after intervention with the device
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Table 5 Severity of OSA in PRS infants undergoing surgical procedures for airway management Authors
Type of procedure
Severity of OSA
Hong et al [62] Looby et al [49] Flores et al [39] Morovic et al [60] Monasterio et al [51]
MDO MDO MDO TLA MDO MDO
Hammoudeh et al [44] Sedaghat et al [45] Genecov et al [50] Cheng et al [40]
MDO TLA MDO MDO, TLA
Mean AHI 6.4 AHI 10.57 (0 -43) Mean AHI 47 Mean AHI 37.6 AHI 18 - 25 Mean AI 18.3 Mean HI 8.5 Mean AHI 26.8 OAHI 39.7(4.5 – 177) Mean OAHI 52.6 RDI 35 - 50 RDI 27 (3.3 – 45.8)
MDO, mandibular distraction osteogenesis; TLA, tongue lip adhesion.
than using terms mild, moderate and severe as there is no clear correlation with the type of intervention based on such classification. Labelling of OSA associated with PRS as mild, moderate and severe may also be misleading as severe may be interpreted as maximal UAO requiring surgical intervention which may have contributed to the variation in the application of surgical treatment seen in the literature. Another deficiency in the current literature is lack of studies giving comparative data on severity of OSA in PRS infants and the interventions that were successful at various levels of severity. Only one study provided incomplete data addressing this issue [52]. In a recent audit at a neonatal unit in Western Australia, the mean OAHI of PRS infants who were managed in prone position (n=17) was 15.6 (range 3.2-44.4). In those managed with NPA (n=4), it was 48.6 (range 13 – 93.9) (unpublished audit by author). Given the costs and lack of availability of PSG facilities at many centres the question whether PSG is necessary in all PRS needs to be addressed. Management of UAO in PRS infants based on severity determined by oximetry has been well described [21,30]. Using this method, early discharge home with NPA was also achieved [68]. Studies comparing PSG and oximetry in children showed that OAHI correlated highly with desaturation index suggesting that OSA associated with desaturation is a more severe problem [69]. Even though the clarification of the cause of desaturation as central or obstructive is not possible with oximetry, this information may not be essential in majority of PRS infants as the natural history is one of resolution of UAO with time in over 80% of cases. Hence, oximetry can be used as surrogate objective measurement of airway obstruction where PSG is not readily available. However, there are no studies comparing oximetry with PSG in PRS infants. Factors to be considered when ordering PSG are availability, cost, waiting times, a positive saturation monitoring and its potential for improving individual patient care. It has been observed that worse UAO is seen when these infants are awake, active and feeding [46,70] and that UAO is not a function of sleep in them. Some authors have felt that PSG is not essential in the management of PRS infants including the selection of patients for CPAP, NPA [29] or MDO [70] Instead they prefer to rely on clinical signs of UAO such as retractions, stridor, desaturation, hypercarbia and inability to feed [29,70]. Alvarez et al validated a 6-channel respiratory polygraphy against standard PSG to diagnose OSA in children [71] The six channels used were oronasal thermistor, impedance plethysmography, body position sensor, microphone for snoring, ECG and SpO2. Using the same criteria for scoring events as in standard PSG, they derived respiratory disturbance index (defined as respiratory events per hour) which showed an 89.4% correlation with OAHI >3 for diagnosis of OSA. Adopting this method for PRS infants can
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Figure 1. Algorithm for investigation of PRS infant. Note: * MMD is measured by placing the wooden end of a cotton applicator on the apex of the mandibular alveolar ridge in midline and marking the handle where the maxillary alveolar ridge touches it [32]. # Feeding difficulty is defined as inability to finish a bottle feed (Habermann bottle) in 30 min or occurrence of desaturation or choking episodes during feeding [32].
increase the feasibility of limited channel PSG in all PRS infants as it can be performed in the ward. Investigation of PRS infants can be based on the response to initial interventions (Figure 1). PRS infants who are stable in the prone position and have no feeding problems can be monitored with oximetry alone. Those who are stable in prone position but have feeding problems may need PSG to determine if airway obstruction is the cause of the feeding problem. If moderate – severe OSA is detected, NPA could be inserted and feeding reassessed in this group. For the third group of infants who have significant desaturations in prone position on oximetry, NPA is inserted and oximetry repeated. PSG can be delayed if NPA corrects the desaturation episodes. If desaturations persist in spite of NPA, in addition to PSG, flexible nasopharyngoscopy/bronchoscopy should be performed to rule out other structural abnormalities. This pragmatic approach is not evidence based but follows clinical logic. None of the studies have provided information on arousals related to respiratory events in these infants. In order to determine the effect of respiratory events on sleep quality, arousals related to
respiratory events (RERAs) should also be reported in addition to OAHI, CAI and AHI in future studies. Details on performance of PSG should also reveal if the study was conducted in prone [or lateral position], supine position or a combination. Although UAO often improves significantly during the first 6 months in the majority, this is not predictable in the individual patient. A system of objectively documenting the course of UAO regularly by measuring MMD and JI serially and performing oximetry or PSG at regular intervals needs to be in place. This should be undertaken in conjunction with recording weight gain, feeding ability and its assessment from time to time. CONCLUSION PSG can help in grading the severity of UAO in PRS infants objectively and has the potential to guide the selection of appropriate interventions in PRS infants. To enable this, more studies in this cohort of patients that employ standard methods of PSG performance and scoring are required. Data on the severity of OSA, measured in terms of OAHI in PRS infants who failed
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conservative measures are essential in order to standardize the selection of PRS patients for surgical interventions. Questions that remain to be answered also include the optimal timing for the performance of PSG, its impact on discharge planning and the relation between severity of OSA and feeding difficulty in PRS infants. CONFLICTS OF INTEREST none FUTURE RESEARCH DIRECTIONS Determine the severity of OSA in PRS infants that is amenable to management with conservative measures Role of PSG in patient selection for surgical intervention in PRS infants To define the role of PSG in discharge-planning of PRS infants To determine the effect of UAO on sleep quality in infants with PRS Investigate the prognostic value of PSG in predicting resolution of UAO in PRS infants
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Contents lists available at ScienceDirect
Paediatric Respiratory Reviews
Review
Evaluation of upper airway obstruction in infants with Pierre Robin sequence and the role of polysomnography – Review of current evidence Vudum Sridhar Reddy 1,2,* 1 2
Neonatal Emergency Transport Service, Sydney Children’s Hospitals Network, Westmead, Sydney, NSW 2145, Australia School of Medicine and Public Health, University of Newcastle, Callaghan, Newcastle, NSW 2308, Australia
EDUCATIONAL AIMS To enable the reader to know objective methods of assessment of upper airway obstruction in infants with Pierre Robin sequence to understand the current evidence regarding the role of polysomnography in the management of PRS infants to develop a plan for investigation of upper airway obstruction in PRS infants
A R T I C L E I N F O
S U M M A R Y
Keywords: Pierre Robin sequence Polysomnography Oximetry Upper airway obstruction
Pierre Robin sequence (PRS) is a heterogeneous condition presenting with upper airway obstruction (UAO) of varying severity. Polysomnography (PSG) is an objective investigation to assess the severity of obstructive sleep apnea and UAO. Its role in the management of PRS has not been well defined. This review summarizes the available evidence on the role of PSG in the assessment of infants with PRS in the context of other commonly used methods of assessment. ß 2015 Elsevier Ltd. All rights reserved.
INTRODUCTION Pierre Robin sequence (PRS) is the association of micrognathia, glossoptosis and upper airway (UAO) obstruction with or without cleft palate [1–3]. Cleft palate is considered by some as an essential component [4–8]. PRS is causally heterogeneous and phenotypically
* Neonatal Emergency Transport Service, Hawkesbury road, Westmead, NSW 2145. Tel.: +61404541904/61296338700; fax: +61296338782. E-mail address: [email protected]. Abbreviations: AHI, Apnea and hypopnea index: Number of apneas and hypopneas per hour; CAI, Central apnea index; JI, Jaw index; MAI, Mixed apnea index; MDO, Mandibular distraction osteogenesis; MMD, Maxillo-mandibular discrepancy; NPA, Nasopharyngeal airway; OAI, Obstructive apnea index; OAHI, Obstructive apnea hypopnea index: AHI after excluding central apneas; ODI, Oxygen desaturation index: Number of desaturation episodes of > 3% per hour; OMAHI, Obstructive and mixed apnea hypopnea index: same as OAHI; ORDI, Obstructive respiratory disturbance index: same as OAHI; PSG, polysomnography; RDI, Respiratory disturbance index: AHI + RERAs; RERA, Respiratory event related arousals: respiratory events associated with arousals that cannot be classified as apnea or hypopnea; TcO2, Transcutaneous oxygen level; TcCo2, Transcutaneous carbon dioxide level; TLA, Tongue lip adhesion; UAO, Upper airway obstruction. http://dx.doi.org/10.1016/j.prrv.2015.10.001 1526-0542/ß 2015 Elsevier Ltd. All rights reserved.
variable [9]. It is associated with a cleft palate in up to 90% of cases [10,11]. About 50% of PRS cases have additional syndrome, anomaly or chromosomal abnormality (often called syndromic PRS) [4,12,13]. Accurate diagnosis of syndromic PRS is important, as it is associated with worse airway and feeding problems as well as higher mortality and psychomotor retardation [14]. UAO in PRS is primarily due to glossoptosis caused by mandibular hypoplasia. In addition, it may also be due to narrowing of oropharynx caused by collapse of pharyngeal walls [15] and structural abnormalities of larynx and subglottic airway [16,17]. Nonsurgical methods have been reported to be adequate to manage UAO in 40.3% to 84% cases of PRS [18–22]. UAO is associated with feeding problems and growth failure in PRS infants. However, feeding problems may also be due to primary swallowing dysfunction due to oroesophageal motor disorders [23–25]. Objective methods to assess the severity of UAO are essential to target the treatment to the severity of the condition. PSG is a gold standard investigation for detection and quantification of obstructive sleep apnea (OSA) [26]. PSG involves recordings using multiple channels to acquire information regarding sleep states, nasal and
V.S. Reddy / Paediatric Respiratory Reviews 17 (2016) 80–87 Table 1 Channels and sensors used to acquire PSG data [27] Channel/signal
Sensor
EEG ECG EOG
Central C1 and C2 Occipital O1 and O2 electrodes Chest leads Electrodes lateral to the outer canthus vertical electrodes Submental electrodes Thermistor, nasal pressure transducer, end tidal CO2 Inductance plethysmography bands or piezoelectric crystal bands
EMG Nasal/oral airflow Respiratory motion from ribcage and abdomen Oxygen saturation Body movements Sleep position Arterial CO2
Pulse oximetry EMG on legs/arms or accelerometer/actimeter device on the foot Position sensor on back of diaper End tidal CO2 or transcutaneous CO2
EEG, Electroencephalogram; EOG, Electro-occulogram; EMG, Electromyogram; ECG, Electrocardiogram.
oral airflow, respiratory effort, oxygen saturation and CO2 levels (Table 1) during an overnight sleep. The current standard of scoring and reporting PSG events is based on American Academy of Sleep Medicine (AASM) criteria [27] (Table 2). Its role in the management of PRS infants has not been clearly defined. The aim of this review is to evaluate the role of PSG in the context of other commonly used methods for assessment of UAO in these infants.
METHODS Databases MEDLINE, EMBASE, CINAHL were searched with the search strategy [Pierre Robin Syndrome or Pierre Robin Sequence] AND [polysomnography or sleep study or oximetry or oxygen saturation or saturation monitoring or obstructive sleep apnoea or nasopharyngoscopy or laryngoscopy or bronchoscopy] without restriction on study design. Manual search of the reference lists were done to find relevant articles. Studies that used PSG in PRS subjects under 3 months age were included. Information relating to the use of clinical methods, oximetry, laryngoscopy/bronchoscopy and PSG was extracted from the articles.
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Clinical assessment of upper airway obstruction A number of different methods have been used to assess UAO in infants with PRS (Table 3). The most common method of assessment of UAO in PRS infants is beside clinical assessment. A structured method of recording signs of UAO (Table 3) while the infant is lowered during sleep from upright position into supine position has been described [29,30]. If no signs of respiratory distress occurred during this manoeuvre, it is repeated while the infant is sucking a bottle. Maxillo-mandibular discrepancy and Jaw index Objective measures of micrognathia include maxillo-mandibular discrepancy (MMD) and jaw index (JI). MMD is the distance between the maxillary and mandibular alveolar ridges in the midline. MMD 3 mm is considered significant in a newborn [31,32]. This is best measured with infant held in upright position with the mandible approximated to the maxilla passively. Schaefer et al [32] reported a MMD of 3-9 mm in PRS infants who required only prone positioning and 8-10 mm in those treated with TLA in the first month of life. Nasopharyngeal airways (NPA) were not used in their study. MMD normalised due to natural growth of the jaw over the first year of life in these patients. Similarly, JI (distance between the alveolar ridges x maxillary arch/mandibular arch in mm) is a bedside measurement, which can be monitored over time [3,33]. The JI is 4.2 1.8 in normal infants. A JI >10 in a newborn is associated with respiratory and feeding difficulties [3,34]. Bijnen et al reported a JI of 6.5 to 17.2 in infants who underwent TLA in their series [34]. Oximetry
The search revealed 100 articles in English of which 20 original studies reported the use of PSG in PRS infants. The majority of the studies were retrospective case series. There was one small RCT evaluating the effect of an oral appliance in infants with PRS that reported mixed and obstructive apnea index as an outcome measure [28]. Since it was not possible to statistically combine the data from these studies a descriptive review is presented here.
Wagener et al [30], Glynn et al [21] and Schaefer et al [32] reported the use of continuous oxygen saturation monitoring to assess the severity of UAO. A trend analysis showing >5% of total time (24 – 36 hours) spent with saturation 3% desaturation
Clinical assessment Tracheal tug; suprasternal, intercostal and subcostal recessions Audible stridor or stertor Intolerance of supine position Oxygen desaturation in supine and/or prone position Feeding difficulty and/or oxygen desaturation during feeding Maxillo-mandibular discrepancy Jaw index Investigations Oximetry Polysomnography Flexible nasopharyngoscopy and bronchoscopy Cephalometry
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Nasopharyngoscopy and bronchoscopy Fibre optic nasopharyngoscopy/bronchoscopy is performed in PRS infants to confirm the site of airway obstruction at the tongue base [37–39] and to diagnose additional anatomical problems. Treatment strategies such a prone positioning, NPA, TLA and mandibular distraction osteogenesis (MDO) are aimed at relief of tongue-base obstruction. Presence of additional anatomical problems will make these interventions less effective [31,32]. Hence, fibreoptic endoscopy is mandatory prior to undertaking surgical procedures for airway management. Problems identified at fibre optic endoscopy include choanal atresia, laryngomalacia, bronchomalacia, tracheomalacia, bronchial stenosis, tracheal stenosis (complete tracheal rings), and subglottic stenosis [16,17,40,41] Fibre optic endoscopy has also been used to position the NPA accurately just superior to the epiglottis [21,37,42]. Bravo et al [43] (2005) compared videonasopharyngoscopy with PSG to predict OSA (defined as ORDI of 5) in PRS children (1month to 4 years age) and reported a sensitivity and specificity of 87% and 100% and positive predictive value and negative predictive values of 100% and 84% respectively. They suggested that videonasopharyngoscopy could be an alternative to PSG to assess the severity of UAO. Polysomnography Early studies of PSG in PRS infants (Table 4) [28,39,40,43–56] demonstrated the use of limited PSG to document severity of UAO, which improved the confidence of carers in decision-making regarding the need for TLA. Freed et al [48] used the information from limited PSG (9 channels) along with TcO2, TcCO2 and oxygen saturation to derive objective criteria for performing TLA. Gilhooly et al [47] used 4-channel PSG to determine the need for TLA and to demonstrate the procedure’s success. Early discharge was facilitated by documentation of absence of significant UAO on PSG. PSG was used during follow up to document resolution of UAO in their patients. Bull et al [46] used limited PSG to document apneas (lasting 15 sec or associated with SpO2 < 90%) and the time spent at different levels of oxygen saturation and end tidal CO2. PSG information was integrated with clinical judgement to guide the nature of airway interventions. A number of studies used PSG to show improvement of measures of OSA after a surgical intervention [34,39,44,45,49,57– 60]. However, few have reported the technique and scoring methods used for PSG and many were performed prior to the publication of AASM criteria. Several authors have reported performing PSG as part of preoperative work up to rule out central apneas, as surgical interventions such as MDO and TLA are unlikely to be successful if central apnoeas predominate [61]. Different cut-offs and more than one index were used to define and grade OSA [eg. AI >5 by Monasterio et al. [51]; ORDI > 5 Bravo et al [43]; OAHI >1 Anderson et al. [55]; AHI >1 Daniel et al. [52]; MOAI >3 Buchenau et al. [28]; and OMAHI >3 MacLean et al [56]]. Studies that correlate the severity of OSA by its metrics with the type of intervention are lacking. Daniel et al [52] graded OSA in PRS infants based on AHI into mild (1-5) moderate (>5-10) and severe (>10). There were 10 mild-moderate and 29 severe cases. Eight mild-moderate and 4 severe cases that required prone position alone for airway management had a mean AHI of 28.9 and a mean OAHI of 22.5. Among the 27 PRS infants who required airway intervention (CPAP alone in 22 and MDO in 5) the mean AHI and mean OAHI were 39 and 30.6 respectively. The severity of OSA in patients undergoing surgical procedures such as MDO or TLA in the studies varied widely from a mean AHI of 6.4 to a mean OAHI of 52.6 (Table 5) suggesting that there is a great variation of practice
in the use of surgical methods in PRS infants [39,40,44,45,49– 51,60,62]. Two cross sectional studies provided PSG data on the severity of OSA in PRS infants using the AASM scoring system. In the first of these studies [55], 13 infants (7 – 214 days age) out of 33 underwent standard 16-channel PSG. OAHI ranged from 0 to 85.7 (mean 33.5; median 9). OSA was diagnosed in 11/13; mild in two (OAHI >1- 3 occurred in all infants with PRS (n=8) and 69% of infants with isolated cleft palate. PRS infants had a higher OMAHI (34.3 5.1) compared with isolated cleft palate infants (7.61.2). Infants who were recommended for intervention (CPAP, Oxygen, MDO) and follow up had an AHI of 31.420 compared with AHI of 11.9 6.4 in those who were advised no intervention [56]. Chang et al [63] reported use of PSG to confirm the resolution of desaturation and obstruction episodes before discontinuing NPA in PRS patients. Wilson et al [64] presented a case series of seven PRS infants in whom PSG was used to document severity of UAO at admission and to confirm its resolution prior to discharge, and during follow up of patients with symptoms such as obstructed breathing or poor weight gain. PSG indices were not reported in these studies. DISCUSSION The purpose of this review was to evaluate the current evidence for the role of PSG in assessing UAO in PRS infants. Most of the literature on this topic consists of retrospective case series. The majority of the studies that included PSG used it to show improvement of one or more measures of OSA after surgery. Details regarding the conduct of PSG or scoring of respiratory events were either incomplete or not provided in the majority of these reports. In the studies that provided the details, methods of performing PSG and the scoring of events varied greatly. Several studies did not provide definitions for the indices used to quantify OSA. The standard definition of OSA in infants and children is AHI > 1 [65,66]. However, this definition does not take into account age related changes in respiratory events in infants in whom obstructive and central apneas decrease with increasing age [67]. Data on normal values for PSG indices in infants is available from studies performed before AASM criteria were published. In those studies, [67] (apnoea defined as cessation of airflow for 3 sec) 90th percentile for obstructive apnea index (OAI) ranged from 0.6 to 0.7 after 2 weeks of age which decreased to 0.2 to 0.4 by 2-3 months of age. Similarly the 90th percentile values for mixed apnoea index (MAI) were 0.3 to 0.5 after 2 weeks of age, decreasing to 0.2 to 0.4 by 2-3 months of age. The 95th percentile for central apnoea index (CAI) was 22 to 45 in 1-3 month age group. So, the combined OAI and MAI is around 1 at 90th centile in normal infants. This estimate does not include hypopnoeas, which are included in the calculation of OAHI and AHI, nor does it include central apnoeas, which are included in AHI. It is not clearly established as to what constitutes pathologically significant OSA in infants. Some authors have used a higher level (>3) of OAHI to define OSA in infants [56]. In the context of PRS, OSA associated with desaturation episodes and/or feeding problems can be considered significant. However feeding problems in PRS infant may also be intrinsic [23,25]. Detection of OSA (as per current definition) in a PRS infant may not need a change of management if the infant is stable in prone position and thriving on oral feeds or nasogastric feeds. Expressing the severity of OSA in terms of OAHI is more meaningful
Table 4 Studies reporting the use of PSG in the assessment of PRS infants Study description
Cases
Age at assessment
Type of PSG used
Scoring methods and PSG indices reported
Definition of OSA and grading
Results, study conclusions, comments
Freed et al., 1988 [48]
Retrospective case series
6 infants in a neonatal unit
1 - 54 days
Scoring of events not defined
Not defined
Bull et al., 1990 [46]
Retrospective, case series
21 infants in a neonatal unit
1 – 8 weeks
nasal/oral thermistor, ETCO2, ECG, SpO2, tachograph thoracic/abdominal strain gauge, diaphragmatic EMG cardiotachometer, SpO2, ETCO2, nasal and oral thermistor, thoracic/ abdominal strain gauge
Apnea significant if lasting 15sec or associated with SpO2 < 90%.
Gilhooly et al., 1993 [47]
Retrospective, case series
13 infants in a neonatal unit
Newborn infants
ECG, abdominal strain gauge or thoracic impedance, ETCO2, SpO2
Scoring of events not defined. % sleep time SpO2 < 90 and < 85; % sleep time ETCO2 > 45; % sleep time obstructive apnoea > 6 sec. Scoring of events not defined
Renault et al., 2000 [53]
Retrospective, case series
24 IPRS infants
Birth – 2 mo
Comprehensive PSG. Daytime nap studies between feeds in supine position
Monasterio et al., 2004 [51]
Clinical series evaluating the effect of MDO
8 – 150 days
Not mentioned
Bravo et al., 2005 [43]
Prospective study comparing videonasopharygoscopy and PSG Retrospective, case series
18 infants who failed prone position 52 PRS children with SDB symptoms 13 infants
4 infants underwent TLA. Objective criteria for TLA were provided based on TcO2, TcCO2, obstructive episodes on PSG and oxygen saturation 18 infants had obstructive apnoea. Based on severity of obstruction patients received TLA or home monitoring with or without oxygen. Grading of severity of obstructive apnoea not defined. 6(46%) had significant UAO and were recommended TLA. Grading of severity of obstructive apnoea not defined. Use of PSG avoids prolonged observation in hospital Number of OMAs 1.8 - 124 per 100 min. OMAs occurred in 19/20 infants with no signs of respiratory distress. OMAs incidence higher in infants with feeding problems and respiratory distress Mean AI 18.3, HI 8.5 before surgery. No episodes of apnoea or hypopnoea occurred after MDO
1mo – 4yr
Comprehensive PSG.
Mean 48 (7 - 214) days
Standard overnight 16 channel PSG
2.72.3 (0.1 – 8.9) mo
Standard PSG.
AASM scoring criteria. AHI OMAHI (Obstructive -mixed apnoea hypopnoea index)
OMAHI of > 3
5 – 141 days?
Standard PSG
AHI 1-5 mild >5-10 moderate >10 severe AHI= number of central and obstructive apneas and hypopneas per hour
8 infants who had TLA
Mean 23 (10 -54) days
Standard 16 channel PSG
Respiratory event significant if lasting > 2 respiratory cycle duration and associated with arousal or >3% desaturation. Apnea is decrease in airflow to 10 severe. No grading applied
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Author, year
Mean preop OAHI 52.6 (7.1 – 85.7); Postop OAHI 10.3 in seven infants showing improvement. OAHI improved from 39.7 (4.5 – 177) to 5.8 (0- 34)
83
0 - 60 days, Median 3 days
0-60 days, Median 5 days
11 infants
15 infants
Components of standard EEG excluding EEG, EOG, EMG
Multichannel PSG 5-99 days 24 in MDO group 15 in TLA group
Components of standard PSG without EEG
Standard PSG? No info on performance 11-310 days 13 infants
Buchenau et al., 2007 [28] Bacher et al., 2011 [54]
Flores et al., 2014 [39]
Looby et al., 2009 [49]
Cross over RCT of pre-epiglottic baton plate case series on efficacy of pre-epiglottic baton plate
Standard PSG 5 days to 6 years 67 infants Genecov et al., 2009 [50]
case series to demonstrate efficacy of MDO Large case series to evaluate efficacy of MDO case series to demonstrate efficacy of MDO Retrospective case series comparing outcomes of MDO and TLA Cheng et al., 2011 [40]
ORDI, Obstructive respiratory distress index; OA, obstructive apnoea; MA, mixed apnoea; AASM, Americal academy of sleep medicine.; AHI, apnoea hypopnoea index. CAI, central apnea index; MOAI, mixed and obstructive apnea index; OAHI, obstructive apnoea hypopnoea index; ODI, oxygen desaturation index.; RDI, respiratory disturbance index. HR, heart rate; ETCO2, end tidal CO2; TcO2, transcutaneous oxygen. TcCO2, transcutaneous carbondioxide; SDB, sleep disordered breathing.
MOAI > 3
Mean MOAI decreased from 13.8 to 3.9 with the device MOAI > 3
Preop mean AHI in MDO group 47 and in TLA group 37.6. At 1 month postop mean AHI 10.9 and 21.6 respectively. At 1 year postop 2.5 and 22.1 respectively none
none
Mean AHI decreased from 10.57(0 -43) to 2.21(0-12.9) after MDO
Preoperative RDI 35 – 50; postoperative RDI 5- 15
Preoperative RDI 3.3 to 45.8 and postoperative RDI 2.2 to 13.6 none
Scoring method not mentioned RDI Scoring method not mentioned RDI Scoring method not mentioned AHI Scoring method not mentioned. AHI. Apnea defined as a cessation of breathing for a duration of 10 sec Scoring as per American Thoracic society 1996. MOAI, CAI, ODI Scoring as per American Thoracic society 1996. MOAI, CAI, ODI Standard PSG 6 infants
Results, study conclusions, comments Definition of OSA and grading Scoring methods and PSG indices reported Type of PSG used Age at assessment Cases Study description Author, year
Table 4 (Continued )
Mean MOAI decreased from 17.2 at admission to 3.8 at discharge after intervention with the device
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Table 5 Severity of OSA in PRS infants undergoing surgical procedures for airway management Authors
Type of procedure
Severity of OSA
Hong et al [62] Looby et al [49] Flores et al [39] Morovic et al [60] Monasterio et al [51]
MDO MDO MDO TLA MDO MDO
Hammoudeh et al [44] Sedaghat et al [45] Genecov et al [50] Cheng et al [40]
MDO TLA MDO MDO, TLA
Mean AHI 6.4 AHI 10.57 (0 -43) Mean AHI 47 Mean AHI 37.6 AHI 18 - 25 Mean AI 18.3 Mean HI 8.5 Mean AHI 26.8 OAHI 39.7(4.5 – 177) Mean OAHI 52.6 RDI 35 - 50 RDI 27 (3.3 – 45.8)
MDO, mandibular distraction osteogenesis; TLA, tongue lip adhesion.
than using terms mild, moderate and severe as there is no clear correlation with the type of intervention based on such classification. Labelling of OSA associated with PRS as mild, moderate and severe may also be misleading as severe may be interpreted as maximal UAO requiring surgical intervention which may have contributed to the variation in the application of surgical treatment seen in the literature. Another deficiency in the current literature is lack of studies giving comparative data on severity of OSA in PRS infants and the interventions that were successful at various levels of severity. Only one study provided incomplete data addressing this issue [52]. In a recent audit at a neonatal unit in Western Australia, the mean OAHI of PRS infants who were managed in prone position (n=17) was 15.6 (range 3.2-44.4). In those managed with NPA (n=4), it was 48.6 (range 13 – 93.9) (unpublished audit by author). Given the costs and lack of availability of PSG facilities at many centres the question whether PSG is necessary in all PRS needs to be addressed. Management of UAO in PRS infants based on severity determined by oximetry has been well described [21,30]. Using this method, early discharge home with NPA was also achieved [68]. Studies comparing PSG and oximetry in children showed that OAHI correlated highly with desaturation index suggesting that OSA associated with desaturation is a more severe problem [69]. Even though the clarification of the cause of desaturation as central or obstructive is not possible with oximetry, this information may not be essential in majority of PRS infants as the natural history is one of resolution of UAO with time in over 80% of cases. Hence, oximetry can be used as surrogate objective measurement of airway obstruction where PSG is not readily available. However, there are no studies comparing oximetry with PSG in PRS infants. Factors to be considered when ordering PSG are availability, cost, waiting times, a positive saturation monitoring and its potential for improving individual patient care. It has been observed that worse UAO is seen when these infants are awake, active and feeding [46,70] and that UAO is not a function of sleep in them. Some authors have felt that PSG is not essential in the management of PRS infants including the selection of patients for CPAP, NPA [29] or MDO [70] Instead they prefer to rely on clinical signs of UAO such as retractions, stridor, desaturation, hypercarbia and inability to feed [29,70]. Alvarez et al validated a 6-channel respiratory polygraphy against standard PSG to diagnose OSA in children [71] The six channels used were oronasal thermistor, impedance plethysmography, body position sensor, microphone for snoring, ECG and SpO2. Using the same criteria for scoring events as in standard PSG, they derived respiratory disturbance index (defined as respiratory events per hour) which showed an 89.4% correlation with OAHI >3 for diagnosis of OSA. Adopting this method for PRS infants can
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Figure 1. Algorithm for investigation of PRS infant. Note: * MMD is measured by placing the wooden end of a cotton applicator on the apex of the mandibular alveolar ridge in midline and marking the handle where the maxillary alveolar ridge touches it [32]. # Feeding difficulty is defined as inability to finish a bottle feed (Habermann bottle) in 30 min or occurrence of desaturation or choking episodes during feeding [32].
increase the feasibility of limited channel PSG in all PRS infants as it can be performed in the ward. Investigation of PRS infants can be based on the response to initial interventions (Figure 1). PRS infants who are stable in the prone position and have no feeding problems can be monitored with oximetry alone. Those who are stable in prone position but have feeding problems may need PSG to determine if airway obstruction is the cause of the feeding problem. If moderate – severe OSA is detected, NPA could be inserted and feeding reassessed in this group. For the third group of infants who have significant desaturations in prone position on oximetry, NPA is inserted and oximetry repeated. PSG can be delayed if NPA corrects the desaturation episodes. If desaturations persist in spite of NPA, in addition to PSG, flexible nasopharyngoscopy/bronchoscopy should be performed to rule out other structural abnormalities. This pragmatic approach is not evidence based but follows clinical logic. None of the studies have provided information on arousals related to respiratory events in these infants. In order to determine the effect of respiratory events on sleep quality, arousals related to
respiratory events (RERAs) should also be reported in addition to OAHI, CAI and AHI in future studies. Details on performance of PSG should also reveal if the study was conducted in prone [or lateral position], supine position or a combination. Although UAO often improves significantly during the first 6 months in the majority, this is not predictable in the individual patient. A system of objectively documenting the course of UAO regularly by measuring MMD and JI serially and performing oximetry or PSG at regular intervals needs to be in place. This should be undertaken in conjunction with recording weight gain, feeding ability and its assessment from time to time. CONCLUSION PSG can help in grading the severity of UAO in PRS infants objectively and has the potential to guide the selection of appropriate interventions in PRS infants. To enable this, more studies in this cohort of patients that employ standard methods of PSG performance and scoring are required. Data on the severity of OSA, measured in terms of OAHI in PRS infants who failed
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conservative measures are essential in order to standardize the selection of PRS patients for surgical interventions. Questions that remain to be answered also include the optimal timing for the performance of PSG, its impact on discharge planning and the relation between severity of OSA and feeding difficulty in PRS infants. CONFLICTS OF INTEREST none FUTURE RESEARCH DIRECTIONS Determine the severity of OSA in PRS infants that is amenable to management with conservative measures Role of PSG in patient selection for surgical intervention in PRS infants To define the role of PSG in discharge-planning of PRS infants To determine the effect of UAO on sleep quality in infants with PRS Investigate the prognostic value of PSG in predicting resolution of UAO in PRS infants
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