Extubation failure in infants with shunt-dependent pulmonary blood flow and univentricular physiology

The objective of the study was to identify incidence, aetiology, and outcomes of extubation failure in infants with shunt-dependent pulmonary blood flow at a single tertiary care, academic children's hospital. The second objective of this study was to determine the haemodynamic effects of transition of positive pressure ventilation to spontaneous breathing in infants with extubation failure.

Extubation failure for our study was defined as the need for positive pressure ventilation within 96 hours after extubation. We collected demographics, pre-operative, intra-operative, post-operative, and peri-extubation data in a retrospective, observational format in patients who underwent a modified Blalock-Taussig shunt between January, 2005 and March, 2011. Infants undergoing Norwood operation or Damus-Kaye-Stansel with modified Blalock-Taussig shunt were excluded from the study. The cardiorespiratory variables collected before extubation and immediately after extubation included heart rate, respiratory rate, mean arterial blood pressure, central venous pressures, near infrared spectroscopy, oxygen saturations, and lactate levels. Clinical outcomes evaluated included the success or failure of extubation, cardiovascular intensive care unit length of stay, hospital length of stay, and mortality. Descriptive and univariate statistics were utilised to compare groups with extubation failure and extubation success.

Of the 55 eligible patients during the study period, extubation failure occurred in 27% (15/55) of the patients. Of the 15 patients with extubation failure, 10 patients needed reintubation and five patients received continuous positive pressure ventilation without getting reintubated. There were three patients who had extubation failure in the first 2 hours after extubation, nine patients in the 2-24-hour period, and three patients in the 24-96-hour period. In all, eight patients were extubated in the second attempt after the first extubation failure, with a median duration of mechanical ventilation of 2 days (1 day, 6 days). The median age of patients at extubation was 19 days (12 days, 22 days) and median weight of patients was 3.6 kg (3.02 kg, 4.26 kg). In all, 38% (21/55) of the patients were intubated before surgery. The most common risk factors for failed extubation were lung disease in 46% (7/15), cardiac dysfunction in 26% (4/15), diaphragmatic paralysis in 13% (2/15), airway oedema in 6% (1/15), and vocal cord paralysis in 6% (1/15). The median duration of mechanical ventilation was 4 days (1 day, 10.5 days), median cardiovascular intensive care unit length of stay was 11 days (6.5 days, 23.5 days), and the median hospital length of stay was 30 days (14 days, 48 days). The overall mortality at the time of hospital discharge was 7%.

Extubation failure in infants with shunt-dependent pulmonary blood flow and univentricular physiology is high and aetiology is diverse. Cardiopulmonary effects of removal of positive pressure ventilation are more pronounced in children with extubation failure and include escalation in the need for oxygen requirement and increase in mean arterial blood pressure. The majority of extubation failures in this select patient population occurs in the first 24 hours. Extubation failure in these patients is not associated with increased hospital length of stay or mortality.