Journal of Neonatal-Perinatal Medicine 7 (2014) 119–124 DOI 10.3233/NPM-1474113 IOS Press
119
Original Research
Positive distending pressure produced by heated, humidified high flow nasal cannula as compared to nasal continuous positive airway pressure in premature infants S. Al-Alaiyan∗ , M. Dawoud and F. Al-Hazzani Department of Pediatrics, Neonatology Section, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
Received 31 July 2013 Revised 27 September 2013 Accepted 25 March 2014
Abstract. OBJECTIVE: our objective is to assess the positive distending pressure generated by high flow nasal cannula and nasal continuous positive airway pressure by measuring the end esophageal pressure in premature infants. STUDY DESIGN: This is a pilot, non-randomized, open label, uncontrolled, crossover assignment study that included neonates born with a birth weight of 1750 grams or less and receiving nCPAP ventilatory support for 24 hrs or more and requiring FiO2 21–50% on nCPAP. Each infant was started on nCPAP at 4, 6 and 8 cm H2 O then on three levels of HHHFNC, 4 L/min, 6 L/min and 8 L/min with 4 hours interval on each flow level. Esophageal pressure (EP), apnea of prematurity, FiO2 requirements and bradycardia were recorded during the different levels of CPAP and HHHFNC use. RESULTS: The study showed that there were no complications observed during the study such as pneumothorax. It showed that EP created by the three different levels of HHHFNC were slightly higher than that EPs created by the three different levels of nCPAP, but statistically not significant. There was no significant change in the FiO2 requirements during the study. There was a trend towards the improvement of oxygen saturation in HHHFNC at different levels and it was statistically significant when 8 L/min was used (P 0.0214). The rates of bradycardia and apnea in nCPAP and HHHFNC were low and statistically were not significant, however the episodes of bradycardia were less in HHHFNC and they were statistically significant at the level of 6 L/min. CONCLUSIONS: HHHFNC in premature infants was well-tolerated with no adverse side effects such as pneumothorax, desaturation, apnea and bradycardia. The study also showed that HHHFNC was able to deliver distending pressure equal to nCPAP. Moreover, we have observed a significant improvement in oxygen saturation when higher levels of HHHFNC was used, most probably due to the improvement of infant comfort which is a noticeable feature of HHHFNC. Keywords: Premature infants, CPAP, high flow nasal cannula, respiratory support, esophageal pressure
∗ Corresponding
author: Dr. Saleh Al-Alaiyan, Department of Pediatrics (MBC-58), King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia. Tel.: +966 1 442 7761; Fax: +966 1 442 7784; E-mail: [email protected].
1934-5798/14/$27.50 © 2014 – IOS Press and the authors. All rights reserved
120
S. Al-Alaiyan et al. / High flow nasal cannula versus NCPAP
1. Introduction Non-invasive ventilatory strategies, such as nasal continuous positive airway pressure are used as an alternative to mechanical ventilation in the treatment of RDS. It is thought that nCPAP provides positive distending pressure while minimizing lung inflammation and injury associated with mechanical ventilation [1]. Avoidance of intubation and increased use of nCPAP to treat respiratory distress syndrome has been shown to decrease the incidence of CLD [2, 3]. Early initiation of nasal CPAP has been shown to reduce the need for conventional mechanical ventilation, artificial surfactant, and supplemental oxygen [4]. Nasal CPAP is also being used in combination with surfactant prophylaxis as an effective (and potentially less damaging) support mode capable of reducing the need for long-term mechanical ventilation [5]. The usefulness of nasal CPAP in treating premature infants of less than 28 weeks’ gestation has not been proven [5]. Nevertheless, nCPAP does have some common clinical limitations such as mechanical difficulties in appropriately maintaining the nasal prong apparatus within the small neonatal nose, nasal septal trauma and some premature infants do not tolerate the nCPAP apparatus which mandates to be tightly affixed to their nose and face. Heated, humidified high flow nasal cannula (HHHFNC) has lately been introduced into neonatal respiratory care as a means of providing positive distending pressure to the neonate with respiratory distress syndrome. Sreenan and colleagues [6] found HHHFNC to be as effective as nCPAP in the management of apnea of prematurity and also demonstrated that the positive distending pressure provided by HHHFNC varied with the patient’s weight. In a most recent retrospective study by Shoemaker and his colleagues [7] who compared infants received either nCPAP or HHHFNC as an early mode of respiratory support, they found no differences in deaths, ventilatordays, BPD, blood infections or other outcomes. More infants were intubated for failing early nCPAP compared to early HHHFNC. HHHFNC aims to maximize patient tolerance by employing heated, humidified gas flow through the standard neonatal nasal cannula that is used routinely in neonatal intensive care units. Holleman-Duray et al. [8] found that the highflow nasal cannula use appears safe and well-tolerated and infants extubated to HHHFNC spent fewer days
on the ventilator. It is unclear how much liters per minute of gas flow can be used with the HHHFNC system to achieve a desired distending positive pressures. Spence et al. [9] showed that HHHFNC delivers significant intrapharyngeal pressure and is potentially a well-tolerated and viable option to provide CPAP at flows of greater than or equal to 3 min/L in infants with respiratory distress. There is a concern that the work of breathing (WOB) of infants on HHHFNC is higher in comparison to nCPAP. Saslow et al. [10] demonstrated that no differences were found in the WOB for all settings between infants treated with HHHFNC or nCPAP. HHHFNC seems to have been rapidly accepted because of their simplicity, ease of use, and the introduction of a device that permits adequate heating and humidification [11]. A number of centers use high-flow nasal cannula in the management of AOP and to support respiratory distress in premature infants, because of their simplicity, ease to use, well tolerated by infants, decreased nasal septum erosion, and adequate heating and humidification. However HHHFNC are used without measuring the positive distending pressure generated. The aim of the study was to evaluate different levels of HHHFNC gas flow required to produce an equivalent positive distending pressure as that provided by different levels of nasal continuous positive airway pressure, assess the relationships between the flow required to generate an equal positive distending pressure (PDP) to that produced by nCPAP and determine the patient tolerability and efficacy outcomes.
2. Materials and methods 2.1. Design This is a pilot, non-randomized, open label, uncontrolled, crossover assignment study. All neonates born with a birth weight of 1750 grams or less and receiving nCPAP ventilatory support for 24 hrs or more and requiring FiO2 21–50% on nCPAP were enrolled in the study. Infants were excluded from the study if they required FiO2 >50%, or diagnosed with congenital anomalies, cyanotic CHD, neuromuscular disorder, pneumothorax, on sedation affecting their breathing or removed by the treating physician before completing the study. Each infant was started on NCPAP at 4, 6 and 8 cm H2 O provided by Dr¨ager Medical’s Babylog 8000 plus
S. Al-Alaiyan et al. / High flow nasal cannula versus NCPAP
then after completing the three levels on nCPAP, the infant was placed on three levels of HHHFNC, 4 L/min, 6 L/min and 8 L/min with 4 hours interval on each flow level. HHHFNC set-up consisted of gas source, air-oxygen blender, Precision flow nasal cannula and Vapotherm HFNC (Vapotherm, Stevensville, Maryland). Appropriately sized nasal cannulae were used according to the used protocol in our unit: outer diameter of 0.14 cm for
119
Original Research
Positive distending pressure produced by heated, humidified high flow nasal cannula as compared to nasal continuous positive airway pressure in premature infants S. Al-Alaiyan∗ , M. Dawoud and F. Al-Hazzani Department of Pediatrics, Neonatology Section, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia
Received 31 July 2013 Revised 27 September 2013 Accepted 25 March 2014
Abstract. OBJECTIVE: our objective is to assess the positive distending pressure generated by high flow nasal cannula and nasal continuous positive airway pressure by measuring the end esophageal pressure in premature infants. STUDY DESIGN: This is a pilot, non-randomized, open label, uncontrolled, crossover assignment study that included neonates born with a birth weight of 1750 grams or less and receiving nCPAP ventilatory support for 24 hrs or more and requiring FiO2 21–50% on nCPAP. Each infant was started on nCPAP at 4, 6 and 8 cm H2 O then on three levels of HHHFNC, 4 L/min, 6 L/min and 8 L/min with 4 hours interval on each flow level. Esophageal pressure (EP), apnea of prematurity, FiO2 requirements and bradycardia were recorded during the different levels of CPAP and HHHFNC use. RESULTS: The study showed that there were no complications observed during the study such as pneumothorax. It showed that EP created by the three different levels of HHHFNC were slightly higher than that EPs created by the three different levels of nCPAP, but statistically not significant. There was no significant change in the FiO2 requirements during the study. There was a trend towards the improvement of oxygen saturation in HHHFNC at different levels and it was statistically significant when 8 L/min was used (P 0.0214). The rates of bradycardia and apnea in nCPAP and HHHFNC were low and statistically were not significant, however the episodes of bradycardia were less in HHHFNC and they were statistically significant at the level of 6 L/min. CONCLUSIONS: HHHFNC in premature infants was well-tolerated with no adverse side effects such as pneumothorax, desaturation, apnea and bradycardia. The study also showed that HHHFNC was able to deliver distending pressure equal to nCPAP. Moreover, we have observed a significant improvement in oxygen saturation when higher levels of HHHFNC was used, most probably due to the improvement of infant comfort which is a noticeable feature of HHHFNC. Keywords: Premature infants, CPAP, high flow nasal cannula, respiratory support, esophageal pressure
∗ Corresponding
author: Dr. Saleh Al-Alaiyan, Department of Pediatrics (MBC-58), King Faisal Specialist Hospital and Research Centre, P.O. Box 3354, Riyadh 11211, Saudi Arabia. Tel.: +966 1 442 7761; Fax: +966 1 442 7784; E-mail: [email protected].
1934-5798/14/$27.50 © 2014 – IOS Press and the authors. All rights reserved
120
S. Al-Alaiyan et al. / High flow nasal cannula versus NCPAP
1. Introduction Non-invasive ventilatory strategies, such as nasal continuous positive airway pressure are used as an alternative to mechanical ventilation in the treatment of RDS. It is thought that nCPAP provides positive distending pressure while minimizing lung inflammation and injury associated with mechanical ventilation [1]. Avoidance of intubation and increased use of nCPAP to treat respiratory distress syndrome has been shown to decrease the incidence of CLD [2, 3]. Early initiation of nasal CPAP has been shown to reduce the need for conventional mechanical ventilation, artificial surfactant, and supplemental oxygen [4]. Nasal CPAP is also being used in combination with surfactant prophylaxis as an effective (and potentially less damaging) support mode capable of reducing the need for long-term mechanical ventilation [5]. The usefulness of nasal CPAP in treating premature infants of less than 28 weeks’ gestation has not been proven [5]. Nevertheless, nCPAP does have some common clinical limitations such as mechanical difficulties in appropriately maintaining the nasal prong apparatus within the small neonatal nose, nasal septal trauma and some premature infants do not tolerate the nCPAP apparatus which mandates to be tightly affixed to their nose and face. Heated, humidified high flow nasal cannula (HHHFNC) has lately been introduced into neonatal respiratory care as a means of providing positive distending pressure to the neonate with respiratory distress syndrome. Sreenan and colleagues [6] found HHHFNC to be as effective as nCPAP in the management of apnea of prematurity and also demonstrated that the positive distending pressure provided by HHHFNC varied with the patient’s weight. In a most recent retrospective study by Shoemaker and his colleagues [7] who compared infants received either nCPAP or HHHFNC as an early mode of respiratory support, they found no differences in deaths, ventilatordays, BPD, blood infections or other outcomes. More infants were intubated for failing early nCPAP compared to early HHHFNC. HHHFNC aims to maximize patient tolerance by employing heated, humidified gas flow through the standard neonatal nasal cannula that is used routinely in neonatal intensive care units. Holleman-Duray et al. [8] found that the highflow nasal cannula use appears safe and well-tolerated and infants extubated to HHHFNC spent fewer days
on the ventilator. It is unclear how much liters per minute of gas flow can be used with the HHHFNC system to achieve a desired distending positive pressures. Spence et al. [9] showed that HHHFNC delivers significant intrapharyngeal pressure and is potentially a well-tolerated and viable option to provide CPAP at flows of greater than or equal to 3 min/L in infants with respiratory distress. There is a concern that the work of breathing (WOB) of infants on HHHFNC is higher in comparison to nCPAP. Saslow et al. [10] demonstrated that no differences were found in the WOB for all settings between infants treated with HHHFNC or nCPAP. HHHFNC seems to have been rapidly accepted because of their simplicity, ease of use, and the introduction of a device that permits adequate heating and humidification [11]. A number of centers use high-flow nasal cannula in the management of AOP and to support respiratory distress in premature infants, because of their simplicity, ease to use, well tolerated by infants, decreased nasal septum erosion, and adequate heating and humidification. However HHHFNC are used without measuring the positive distending pressure generated. The aim of the study was to evaluate different levels of HHHFNC gas flow required to produce an equivalent positive distending pressure as that provided by different levels of nasal continuous positive airway pressure, assess the relationships between the flow required to generate an equal positive distending pressure (PDP) to that produced by nCPAP and determine the patient tolerability and efficacy outcomes.
2. Materials and methods 2.1. Design This is a pilot, non-randomized, open label, uncontrolled, crossover assignment study. All neonates born with a birth weight of 1750 grams or less and receiving nCPAP ventilatory support for 24 hrs or more and requiring FiO2 21–50% on nCPAP were enrolled in the study. Infants were excluded from the study if they required FiO2 >50%, or diagnosed with congenital anomalies, cyanotic CHD, neuromuscular disorder, pneumothorax, on sedation affecting their breathing or removed by the treating physician before completing the study. Each infant was started on NCPAP at 4, 6 and 8 cm H2 O provided by Dr¨ager Medical’s Babylog 8000 plus
S. Al-Alaiyan et al. / High flow nasal cannula versus NCPAP
then after completing the three levels on nCPAP, the infant was placed on three levels of HHHFNC, 4 L/min, 6 L/min and 8 L/min with 4 hours interval on each flow level. HHHFNC set-up consisted of gas source, air-oxygen blender, Precision flow nasal cannula and Vapotherm HFNC (Vapotherm, Stevensville, Maryland). Appropriately sized nasal cannulae were used according to the used protocol in our unit: outer diameter of 0.14 cm for
