Letters to the Editor
of concordance (94% and 92%, respectively) between CXR and BUS to ascertain catheter tip location and revealed incorrect and/or potentially risky locations with a moderate-to-good κ value, even when the sample size was small. In addition, we demonstrated clear statistically significant differences in time consumption between the two techniques. Increasing sample size will presumably reinforce our conclusions by increasing the degree of concordance as assessed by κ statistics, but it will not change the sense of our observations. In our study, selection of CVC location was made according to patients’ characteristics and usual PICU protocols. We included femoral cannulations because this vascular location is commonly used in critically ill children in most Spanish PICUs (2). Verification of CVC tip in lower body venous access is quite straight forward using the subcostal view of the inferior vena cava and right atrium (3, 4). However, location of CVC in upper body accesses is much more problematic. As demonstrated in our study, BUS views other than subcostal are frequently needed, which may require a more skilled ultrasound operator. In our opinion, future studies should analyze BUS performance in verification of upper and lower body CVC tips separately. In our study, a single PICU physician performed all the examinations. This operator received formal training in pediatric echocardiography during a 6-month period in a national reference cardiothoracic surgery center. This training included supervised performance of more than 300 standard echocardiograms in patients with congenital heart disease both before and after surgery in the PICU. As we discussed, this fact should be taken into account to avoid the generalization of our results especially regarding the ability to detect catheter tips within the superior vena cava. We agree that a larger prospective study is needed and should include more physicians who perform and interpret BUS and CXR in order to test interrater and intrarater concordance. Colleti Junior and de Carvalho (1) also suggest to follow long-term CVC complications. This would be very interesting, but because complications do not depend on the method of CVC tip verification, this analysis was not planned. Finally, a cost analysis of BUS should be one of the critical aspects to analyze before generalization of BUS and any other innovative technique. This would be, however, a hard task to do because many factors should be taken into account, such as equipment, methods and cost of training, avoidance of other procedures, and imaging test (5). Verification of CVC tip is just one of the BUS many applications in the PICU, an important point when comparing the cost of individual ultrasound applications against a standard technique. In conclusion, we consider that our study should be interpreted as a proof of concept and needs to be confirmed by multicentric prospective studies involving all kind of PICU patients and BUS operators with different levels of BUS training. This is essential before CXR can be substituted by BUS in the routine verification of catheter tip position in critically ill children. The authors have disclosed that they do not have any potential conflicts of interest. Paula Alonso-Quintela, MD, Ignacio Oulego-Erroz, MD, Pediatric Critical Care Unit, Department of Pediatrics, Complejo
Pediatric Critical Care Medicine
Asistencial Universitario de León, León, Spain; Antonio Rodríguez-Nuñez, MD, PhD, Pediatric Emergency and Critical Care Division, Clinical Universitary Hospital, University of Santiago de Compostela, Institute of Investigation of Santiago (IDIS), Santiago de Compostela, Santiago, Spain, and Research Network on Maternal and Child Health and Development II (Red SAMID II), Spanish Health Institute Carlos III, Madrid, Spain
REFERENCES
1. Colleti Junior J, de Carvalho WB: Still a Way to Go: The Substitution of the x-Ray as the Gold Standard to Locate the Right Placement of Central Venous Catheter. Pediatr Crit Care Med 2016; 17:184 2. Rey C, Alvarez F, De La Rua V, et al: Mechanical complications during central venous cannulations in pediatric patients. Intensive Care Med 2009; 35:1438–1443 3. Michel F, Brevaut-Malaty V, Pasquali R, et al: Comparison of ultrasound and X-ray in determining the position of umbilical venous catheters. Resuscitation 2012; 83:705–709 4. Hoellering AB, Koorts PJ, Cartwright DW, et al: Determination of umbilical venous catheter tip position with radiograph. Pediatr Crit Care Med 2014; 15:56–61 5. Oks M, Cleven KL, Cardenas-Garcia J, et al: The effect of point-ofcare ultrasonography on imaging studies in the medical ICU: A comparative study. Chest 2014; 146:1574–1577 DOI: 10.1097/PCC.0000000000000592
Noninvasive Ventilation in Pediatric Acute Respiratory Distress Syndrome. Where Is the Limit? To the Editor:
W
e have read with interest in a recent issue of Pediatric Critical Care Medicine the article by Essouri et al (1). We are in agreement with the conclusions of the indications of noninvasive ventilation (NIV) in mild and severe pediatric acute respiratory distress syndromes (PARDS): 1) in select populations, such as children with mild ARDS, the addition of noninvasive positive pressure ventilation (NPPV) to standard medical therapy may prevent intubation and mechanical ventilation; and 2) the high level of NPPV failure in moderate and severe ARDS suggests that NPPV is not indicated in those populations. But, in our opinion, according to published data (2), some patients with moderate ARDS can benefit from an NIV trial with a time-defined limit to indicate when intubation should be established. The authors describe different prognostic factors of NIV failure. However, they did not establish clear clinical variables for criteria failure. Antonelli et al (2) found a 56% mortality in patients treated with NIV and finally intubated for failure of this therapy. A cutoff point after 1 hour of treatment was established Pao2/Fio2 (PF) ratio of less than 175 for predicting the failure of NIV in hypoxemic patients. This inadmissible mortality has been blamed for a possible delay in intubation of these patients. There is agreement not to start NIV in severe ARDS because it has been shown that delaying intubation increases the mortality. But, in our opinion, some patients with moderate ARDS www.pccmjournal.org
185
Copyright © 2016 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies. Unauthorized reproduction of this article is prohibited
Letters to the Editor
can benefit from an NIV trial. Nevertheless, it should be mandatory to send a clear and cautious message about the time and the cutoff levels to stop NIV in this scenario based on current evidence–based medicine level of knowledge. According to a previously cited article, if after 1 hour of NIV, an improvement in PF ratio greater than 175 is not obtained, the patient should be intubated in order to improve the level of recruitment and to minimize the intrapulmonary shunt. Some authors confirmed similar cutoff levels in pediatric patients using Spo2/Fio2 ratio as a surrogate of PF ratio (3, 4). As a conclusion, experienced units with appropriate material could start NIV in patients suffering with moderate ARDS, making sure that an appropriate recruitment is achieved in the first 2 hours. Dr. Pons-Òdena received funding from Maquet Getinge group and from Fisher and Paykel. The remaining authors have disclosed that they do not have any potential conflicts of interest. Alberto Medina-Villanueva, MD, PhD, Pediatric Intensive Care Unit, Department of Pediatrics, Hospital Universitario Central de Asturias, Oviedo, Spain; Vicent Modesto i Alapont, MD, PhD, Pediatric Intensive Care Unit, Department of Pediatrics, Hospital Universitari i Politècnic La Fe, València, Spain; Martí Pons-Òdena, MD, PhD, Pediatric Intensive Care Unit, Department of Pediatrics, Hospital Universitari Sant Joan de Déu, Barcelona, Spain
REFERENCES
1. Essouri S, Carroll C; Pediatric Acute Lung Injury Consensus Conference Group: Noninvasive Support and Ventilation for Pediatric Acute Respiratory Distress Syndrome: Proceedings From the Pediatric Acute Lung Injury Consensus Conference. Pediatr Crit Care Med 2015; 16:S102–S110 2. Antonelli M, Conti G, Esquinas A, et al: A multiple-center survey on the use in clinical practice of noninvasive ventilation as a first-line intervention for acute respiratory distress syndrome. Crit Care Med 2007; 35:18–25 3. Mayordomo-Colunga J, Pons M, López Y, et al: Predicting noninvasive ventilation failure in children from the SpO2/FiO2 (SF) ratio. Intensive Care Med 2013; 39:1095–1103 4. Pons-Odena M, Palanca D, Modesto V, et al: SpO2/FiO2 (SF ratio) as a predictor of NIV failure in children with hypoxemic respiratory insufficiency. J Pediatr Intensive Care 2013; 2:111–119 DOI: 10.1097/PCC.0000000000000591
The authors reply:
W
e thank Medina-Villanueva et al (1) for their correspondence on our recently published consensus statement on noninvasive positive pressure ventilation (NPPV) and pediatric acute respiratory distress syndrome (PARDS) (2). We are also grateful for the opportunity to clarify the points raised. We are pleased that the authors agree that the use of NPPV is appropriate for some children with PARDS, particularly in children with mild PARDS. In addition, we agree that defining limits of NPPV are important and that determining the appropriate limits of NPPV in individual children is challenging. Just as a provider should not unnecessarily intubate children who might recover from their illness on noninvasive support (thus exposing them to the complications of intubation and invasive 186
www.pccmjournal.org
mechanical ventilation), a provider should not to put children at unnecessary risk by delaying intubation. In addition to the two pediatric trials cited by Medina-Villanueva et al (1), other investigators have attempted to determine limits to how long NPPV should be applied and in which children (3–6). Unfortunately, because of the relatively small numbers of children who receive NPPV, these trials include a heterogeneous population of children and not only those children with PARDS. In a small study by Bernet et al (5) of 42 children with acute respiratory failure, an Fio2 of more than 80% after 1 hour of NPPV predicted nonresponse with a sensitivity of 56% and a specificity of 83%. The study by Antonelli et al (7) also used an assessment of oxygenation as a cutoff for NPPV nonresponse, and although this was a well-conducted study, it targeted a population of adults with a mean age greater than 50 years and should not be extrapolated to children. The study by Pons-Odena et al (4) in this area is among the largest of these trials, but still it only includes 34 patients; of which, only seven had NPPV nonresponse or “failure”. These data represent a good starting point, but these small studies in children provide insufficient data for defining an evidence-based cutoff. Until larger studies are conducted, we recommend that clinicians use an individualized approach to determining when a child “fails” NPPV. This assessment should include a child’s acute and chronic disease states, age and developmental status, physiologic variables, including assessments of oxygenation and ventilation, physical examination findings, and duration of time on NPPV. The authors have disclosed that they do not have any potential conflicts of interest. Sandrine Essouri, MD, PhD, Pediatric Intensive Care Unit CHU Kremlin Bicetre, Assistance Publique-Hôpitaux de Paris, Paris South University, Orsay, France; Christopher Carroll, MD, MS, Department of Pediatrics, Connecticut Children’s Medical Center, Hartford, CT; on behalf of the Pediatric Acute Lung Injury Consensus Conference Group
REFERENCES
1. Medina-Villanueva A, Alapont VM, Pons-Odena M: Noninvasive Ventilation in Pediatric Acute Respiratory Distress Syndrome. Where Is the Limit? Pediatr Crit Care Med 2016; 17:185–186 2. Essouri S, Carroll C; Pediatric Acute Lung Injury Consensus Conference Group: Noninvasive support and ventilation for pediatric acute respiratory distress syndrome: Proceedings from the Pediatric Acute Lung Injury Consensus Conference. Pediatr Crit Care Med 2015; 16:S102–S110 3. Mayordomo-Colunga J, Pons M, López Y, et al: Predicting noninvasive ventilation failure in children from the SpO2/FiO2 (SF) ratio. Intensive Care Med 2013; 39:1095–1103 4. Pons-Odena M, Palanca D, Modesto V, et al: SpO2/FiO2 (SF ratio) as a predictor of NIV failure in children with hypoxemic respiratory insufficiency. J Pediatr Intensive Care 2013; 2:111–119 5. Bernet V, Hug MI, Frey B: Predictive factors for the success of noninvasive mask ventilation in infants and children with acute respiratory failure. Pediatr Crit Care Med 2005; 6:660–664 6. Padman R, Lawless ST, Kettrick RG: Noninvasive ventilation via bilevel positive airway pressure support in pediatric practice. Crit Care Med 1998; 26:169–173 7. Antonelli M, Conti G, Esquinas A, et al: A multiple-center survey on the use in clinical practice of noninvasive ventilation as a first-line intervention for acute respiratory distress syndrome. Crit Care Med 2007; 35:18–25 DOI: 10.1097/PCC.0000000000000595 February 2016 • Volume 17 • Number 2
Copyright © 2016 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies. Unauthorized reproduction of this article is prohibited
of concordance (94% and 92%, respectively) between CXR and BUS to ascertain catheter tip location and revealed incorrect and/or potentially risky locations with a moderate-to-good κ value, even when the sample size was small. In addition, we demonstrated clear statistically significant differences in time consumption between the two techniques. Increasing sample size will presumably reinforce our conclusions by increasing the degree of concordance as assessed by κ statistics, but it will not change the sense of our observations. In our study, selection of CVC location was made according to patients’ characteristics and usual PICU protocols. We included femoral cannulations because this vascular location is commonly used in critically ill children in most Spanish PICUs (2). Verification of CVC tip in lower body venous access is quite straight forward using the subcostal view of the inferior vena cava and right atrium (3, 4). However, location of CVC in upper body accesses is much more problematic. As demonstrated in our study, BUS views other than subcostal are frequently needed, which may require a more skilled ultrasound operator. In our opinion, future studies should analyze BUS performance in verification of upper and lower body CVC tips separately. In our study, a single PICU physician performed all the examinations. This operator received formal training in pediatric echocardiography during a 6-month period in a national reference cardiothoracic surgery center. This training included supervised performance of more than 300 standard echocardiograms in patients with congenital heart disease both before and after surgery in the PICU. As we discussed, this fact should be taken into account to avoid the generalization of our results especially regarding the ability to detect catheter tips within the superior vena cava. We agree that a larger prospective study is needed and should include more physicians who perform and interpret BUS and CXR in order to test interrater and intrarater concordance. Colleti Junior and de Carvalho (1) also suggest to follow long-term CVC complications. This would be very interesting, but because complications do not depend on the method of CVC tip verification, this analysis was not planned. Finally, a cost analysis of BUS should be one of the critical aspects to analyze before generalization of BUS and any other innovative technique. This would be, however, a hard task to do because many factors should be taken into account, such as equipment, methods and cost of training, avoidance of other procedures, and imaging test (5). Verification of CVC tip is just one of the BUS many applications in the PICU, an important point when comparing the cost of individual ultrasound applications against a standard technique. In conclusion, we consider that our study should be interpreted as a proof of concept and needs to be confirmed by multicentric prospective studies involving all kind of PICU patients and BUS operators with different levels of BUS training. This is essential before CXR can be substituted by BUS in the routine verification of catheter tip position in critically ill children. The authors have disclosed that they do not have any potential conflicts of interest. Paula Alonso-Quintela, MD, Ignacio Oulego-Erroz, MD, Pediatric Critical Care Unit, Department of Pediatrics, Complejo
Pediatric Critical Care Medicine
Asistencial Universitario de León, León, Spain; Antonio Rodríguez-Nuñez, MD, PhD, Pediatric Emergency and Critical Care Division, Clinical Universitary Hospital, University of Santiago de Compostela, Institute of Investigation of Santiago (IDIS), Santiago de Compostela, Santiago, Spain, and Research Network on Maternal and Child Health and Development II (Red SAMID II), Spanish Health Institute Carlos III, Madrid, Spain
REFERENCES
1. Colleti Junior J, de Carvalho WB: Still a Way to Go: The Substitution of the x-Ray as the Gold Standard to Locate the Right Placement of Central Venous Catheter. Pediatr Crit Care Med 2016; 17:184 2. Rey C, Alvarez F, De La Rua V, et al: Mechanical complications during central venous cannulations in pediatric patients. Intensive Care Med 2009; 35:1438–1443 3. Michel F, Brevaut-Malaty V, Pasquali R, et al: Comparison of ultrasound and X-ray in determining the position of umbilical venous catheters. Resuscitation 2012; 83:705–709 4. Hoellering AB, Koorts PJ, Cartwright DW, et al: Determination of umbilical venous catheter tip position with radiograph. Pediatr Crit Care Med 2014; 15:56–61 5. Oks M, Cleven KL, Cardenas-Garcia J, et al: The effect of point-ofcare ultrasonography on imaging studies in the medical ICU: A comparative study. Chest 2014; 146:1574–1577 DOI: 10.1097/PCC.0000000000000592
Noninvasive Ventilation in Pediatric Acute Respiratory Distress Syndrome. Where Is the Limit? To the Editor:
W
e have read with interest in a recent issue of Pediatric Critical Care Medicine the article by Essouri et al (1). We are in agreement with the conclusions of the indications of noninvasive ventilation (NIV) in mild and severe pediatric acute respiratory distress syndromes (PARDS): 1) in select populations, such as children with mild ARDS, the addition of noninvasive positive pressure ventilation (NPPV) to standard medical therapy may prevent intubation and mechanical ventilation; and 2) the high level of NPPV failure in moderate and severe ARDS suggests that NPPV is not indicated in those populations. But, in our opinion, according to published data (2), some patients with moderate ARDS can benefit from an NIV trial with a time-defined limit to indicate when intubation should be established. The authors describe different prognostic factors of NIV failure. However, they did not establish clear clinical variables for criteria failure. Antonelli et al (2) found a 56% mortality in patients treated with NIV and finally intubated for failure of this therapy. A cutoff point after 1 hour of treatment was established Pao2/Fio2 (PF) ratio of less than 175 for predicting the failure of NIV in hypoxemic patients. This inadmissible mortality has been blamed for a possible delay in intubation of these patients. There is agreement not to start NIV in severe ARDS because it has been shown that delaying intubation increases the mortality. But, in our opinion, some patients with moderate ARDS www.pccmjournal.org
185
Copyright © 2016 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies. Unauthorized reproduction of this article is prohibited
Letters to the Editor
can benefit from an NIV trial. Nevertheless, it should be mandatory to send a clear and cautious message about the time and the cutoff levels to stop NIV in this scenario based on current evidence–based medicine level of knowledge. According to a previously cited article, if after 1 hour of NIV, an improvement in PF ratio greater than 175 is not obtained, the patient should be intubated in order to improve the level of recruitment and to minimize the intrapulmonary shunt. Some authors confirmed similar cutoff levels in pediatric patients using Spo2/Fio2 ratio as a surrogate of PF ratio (3, 4). As a conclusion, experienced units with appropriate material could start NIV in patients suffering with moderate ARDS, making sure that an appropriate recruitment is achieved in the first 2 hours. Dr. Pons-Òdena received funding from Maquet Getinge group and from Fisher and Paykel. The remaining authors have disclosed that they do not have any potential conflicts of interest. Alberto Medina-Villanueva, MD, PhD, Pediatric Intensive Care Unit, Department of Pediatrics, Hospital Universitario Central de Asturias, Oviedo, Spain; Vicent Modesto i Alapont, MD, PhD, Pediatric Intensive Care Unit, Department of Pediatrics, Hospital Universitari i Politècnic La Fe, València, Spain; Martí Pons-Òdena, MD, PhD, Pediatric Intensive Care Unit, Department of Pediatrics, Hospital Universitari Sant Joan de Déu, Barcelona, Spain
REFERENCES
1. Essouri S, Carroll C; Pediatric Acute Lung Injury Consensus Conference Group: Noninvasive Support and Ventilation for Pediatric Acute Respiratory Distress Syndrome: Proceedings From the Pediatric Acute Lung Injury Consensus Conference. Pediatr Crit Care Med 2015; 16:S102–S110 2. Antonelli M, Conti G, Esquinas A, et al: A multiple-center survey on the use in clinical practice of noninvasive ventilation as a first-line intervention for acute respiratory distress syndrome. Crit Care Med 2007; 35:18–25 3. Mayordomo-Colunga J, Pons M, López Y, et al: Predicting noninvasive ventilation failure in children from the SpO2/FiO2 (SF) ratio. Intensive Care Med 2013; 39:1095–1103 4. Pons-Odena M, Palanca D, Modesto V, et al: SpO2/FiO2 (SF ratio) as a predictor of NIV failure in children with hypoxemic respiratory insufficiency. J Pediatr Intensive Care 2013; 2:111–119 DOI: 10.1097/PCC.0000000000000591
The authors reply:
W
e thank Medina-Villanueva et al (1) for their correspondence on our recently published consensus statement on noninvasive positive pressure ventilation (NPPV) and pediatric acute respiratory distress syndrome (PARDS) (2). We are also grateful for the opportunity to clarify the points raised. We are pleased that the authors agree that the use of NPPV is appropriate for some children with PARDS, particularly in children with mild PARDS. In addition, we agree that defining limits of NPPV are important and that determining the appropriate limits of NPPV in individual children is challenging. Just as a provider should not unnecessarily intubate children who might recover from their illness on noninvasive support (thus exposing them to the complications of intubation and invasive 186
www.pccmjournal.org
mechanical ventilation), a provider should not to put children at unnecessary risk by delaying intubation. In addition to the two pediatric trials cited by Medina-Villanueva et al (1), other investigators have attempted to determine limits to how long NPPV should be applied and in which children (3–6). Unfortunately, because of the relatively small numbers of children who receive NPPV, these trials include a heterogeneous population of children and not only those children with PARDS. In a small study by Bernet et al (5) of 42 children with acute respiratory failure, an Fio2 of more than 80% after 1 hour of NPPV predicted nonresponse with a sensitivity of 56% and a specificity of 83%. The study by Antonelli et al (7) also used an assessment of oxygenation as a cutoff for NPPV nonresponse, and although this was a well-conducted study, it targeted a population of adults with a mean age greater than 50 years and should not be extrapolated to children. The study by Pons-Odena et al (4) in this area is among the largest of these trials, but still it only includes 34 patients; of which, only seven had NPPV nonresponse or “failure”. These data represent a good starting point, but these small studies in children provide insufficient data for defining an evidence-based cutoff. Until larger studies are conducted, we recommend that clinicians use an individualized approach to determining when a child “fails” NPPV. This assessment should include a child’s acute and chronic disease states, age and developmental status, physiologic variables, including assessments of oxygenation and ventilation, physical examination findings, and duration of time on NPPV. The authors have disclosed that they do not have any potential conflicts of interest. Sandrine Essouri, MD, PhD, Pediatric Intensive Care Unit CHU Kremlin Bicetre, Assistance Publique-Hôpitaux de Paris, Paris South University, Orsay, France; Christopher Carroll, MD, MS, Department of Pediatrics, Connecticut Children’s Medical Center, Hartford, CT; on behalf of the Pediatric Acute Lung Injury Consensus Conference Group
REFERENCES
1. Medina-Villanueva A, Alapont VM, Pons-Odena M: Noninvasive Ventilation in Pediatric Acute Respiratory Distress Syndrome. Where Is the Limit? Pediatr Crit Care Med 2016; 17:185–186 2. Essouri S, Carroll C; Pediatric Acute Lung Injury Consensus Conference Group: Noninvasive support and ventilation for pediatric acute respiratory distress syndrome: Proceedings from the Pediatric Acute Lung Injury Consensus Conference. Pediatr Crit Care Med 2015; 16:S102–S110 3. Mayordomo-Colunga J, Pons M, López Y, et al: Predicting noninvasive ventilation failure in children from the SpO2/FiO2 (SF) ratio. Intensive Care Med 2013; 39:1095–1103 4. Pons-Odena M, Palanca D, Modesto V, et al: SpO2/FiO2 (SF ratio) as a predictor of NIV failure in children with hypoxemic respiratory insufficiency. J Pediatr Intensive Care 2013; 2:111–119 5. Bernet V, Hug MI, Frey B: Predictive factors for the success of noninvasive mask ventilation in infants and children with acute respiratory failure. Pediatr Crit Care Med 2005; 6:660–664 6. Padman R, Lawless ST, Kettrick RG: Noninvasive ventilation via bilevel positive airway pressure support in pediatric practice. Crit Care Med 1998; 26:169–173 7. Antonelli M, Conti G, Esquinas A, et al: A multiple-center survey on the use in clinical practice of noninvasive ventilation as a first-line intervention for acute respiratory distress syndrome. Crit Care Med 2007; 35:18–25 DOI: 10.1097/PCC.0000000000000595 February 2016 • Volume 17 • Number 2
Copyright © 2016 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies. Unauthorized reproduction of this article is prohibited
