Pulmonary Dysfunction and Therapeutic Hypothermia in Asphyxiated Newborns: Whole Body versus Selective Head Cooling

ABSTRACT

Compared with whole body cooling (WBC), selective head cooling (SHC) of asphyxiated newborns presumably allows effective brain cooling with less systemic hypothermia and potentially fewer systemic adverse effects. It is not known if pulmonary dysfunction, one of the potential adverse systemic effects of therapeutic hypothermic neuroprotection, differs with the method of cooling. We sought to investigate if pulmonary mechanics and gas exchange during therapeutic hypothermia differ between WBC and SHC. The severity of pulmonary dysfunction was determined in 59 asphyxiated newborns receiving therapeutic hypothermic neuroprotection by either SHC (n = 31) or WBC (n = 28). Ventilatory parameters and simultaneous alveolar-arterial oxygen gradient (A-a DO₂) and partial pressure of carbon dioxide, arterial (PaCO₂) were measured before the start of cooling (baseline), and at 4, 8, 12, 24, 48, and 72 hours of cooling. The diagnosis of persistent pulmonary hypertension of the newborn (PPHN) was established by echocardiography. Clinical monitoring and treatment during cooling, whether SHC or WBC, were similar. All (96%) but two infants (from the SHC group) required mechanical ventilation of varying duration during cooling, and nine infants (15%) developed PPHN. The baseline ventilator pressures requirement, and A-a DO₂ were similar among the 48 ventilated infants without PPHN (WBC 23, SHC 25) at the start of cooling. Ventilatory requirements remained modest and did not differ with the method of cooling. Similar numbers of infants without PPHN were able to be extubated after improvement in respiratory status while being cooled (WBC 42.8% versus SHC 37.9%, p = 0.79, odds ratio [OR] 1.2, 95% confidence interval [CI] 0.4 to 3.5). Nine infants (WBC 5, SHC 4) developed PPHN. Six of the nine (WBC 4, SHC 2) required inhaled nitric oxide therapy, and one infant from the WBC group subsequently required extracorporeal membrane oxygenation. The incidence of PPHN was similar in both the WBC and SHC groups (17.8% versus 12.9%, p = 0.72, OR 1.5, 95% CI 0.3 to 6.1). Pulmonary dysfunction is common but not severe in asphyxiated infants during therapeutic hypothermia. Pulmonary mechanics and gas exchange do not differ with the method of achieving hypothermia.

KEYWORDS

Pulmonary dysfunction - therapeutic hypothermia - asphyxiated newborns - whole body cooling - selective head cooling

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