title: Optimal level of nasal continuous positive airway pressure in severe viral bronchiolitis.
abstract: OBJECTIVE
  To determine the optimal level of nasal continuous positive airway pressure (nCPAP) in infants with severe hypercapnic viral bronchiolitis as assessed by the maximal unloading of the respiratory muscles and improvement of breathing pattern and gas exchange.
  
  
  METHODS
  A prospective physiological study in a tertiary paediatric intensive care unit (PICU). Breathing pattern, gas exchange, intrinsic end expiratory pressure (PEEPi) and respiratory muscle effort were measured in ten infants with severe hypercapnic viral bronchiolitis during spontaneous breathing (SB) and three increasing levels of nCPAP.
  
  
  RESULTS
  During SB, median PEEPi was 6 cmH(2)O (range 3.9-9.2 cmH(2)O), median respiratory rate was 78 breaths/min (range 41-96), median inspiratory time/total duty cycle (T                            (i)/T                            (tot)) was 0.45 (range 0.40-0.48) and transcutaneous carbon dioxide pressure (P                            (tc)CO(2)) was 61.5 mmHg (range 50-78). In all the infants, an nCPAP level of 7 cmH(2)O was associated with the greatest reduction in respiratory effort with a mean reduction in oesophageal and diaphragmatic pressure swings of 48 and 46%, respectively, and of the oesophageal and diaphragmatic pressure time product of 49 and 56%, respectively. During nCPAP, median respiratory rate decreased to 56 breaths/min (range 39-108, p < 0.05), median T                            (i)/T                            (tot) decreased to 0.40 (range 0.34-0.44, p < 0.50) and P                            (tc)CO(2) decreased to 49 mmHg (range 35-65, p < 0.05). Only one infant with associated bacterial pneumonia required intubation and all the infants were discharged alive from the PICU after a median stay of 5.5 (range 3-27 days).
  
  
  CONCLUSIONS
  In infants with hypercapnic respiratory failure due to acute viral bronchiolitis, an nCPAP level of 7 cmH(2)O is associated with the greatest unloading of the respiratory muscles and improvement of breathing pattern, as well as a favourable short-term clinical outcome.
authors: AP-HP, Pediatric Intensive Care Unit, Kremlin-Bicêtre Hospital, 78 rue du Général Leclerc, 94270, Le Kremlin-Bicêtre, France. sandrine.essouri@bct.aphp.fr
authors: Sandrine
authors: S
authors: Essouri
authors: Philippe
authors: P
authors: Durand
authors: Laurent
authors: L
authors: Chevret
authors: Laurent
authors: L
authors: Balu
authors: Denis
authors: D
authors: Devictor
authors: Brigitte
authors: B
authors: Fauroux
authors: Pierre
authors: P
authors: Tissières
mesh_terms: D001990:Bronchiolitis, Viral / Q000503:physiopathology* / Q000628:therapy*; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D005260:Female; D005602:France; D006801:Humans; D006935:Hypercapnia / Q000503:physiopathology*; D007223:Infant; D015278:Intensive Care Units, Pediatric; D008297:Male; D009666:Nose; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012119:Respiration; D018357:Respiratory Syncytial Virus Infections / Q000503:physiopathology / Q000628:therapy; D012136:Respiratory Syncytial Viruses; D012720:Severity of Illness Index