Permissive hypercapnia in infants and children with acute respiratory distress syndrome

Objective

There is increasing evidence that the use of large tidal volumes (Vt) and high peak inspiratory pressures (PIP) during mechanical ventilation (MV) results in severe pulmonary damage. The aim is to present our experience with pressure controlled ventilation (PCV) and permissive hypercapnia (PHC) in paediatric patients with acute respiratory distress syndrome (ARDS).

Design

Prospective case report series.

Setting

A 12 bed multidisciplinary paediatric ICU in a University hospital.

Patients

From October 1993 to October 1996 paediatric patients (8 males, 2 females) with a mean age of 2.6 ± 1.4 years and a mean body weight of 12.5 ± 4.3 kg suffering from severe ARDS were included into this study. Before starting controlled hypoventilation six patients had signs of pulmonary barotrauma.

Methods

All patients were intubated, sedated and paralysed. The goal of mechanical ventilation was to limit PIP to 40 cmH₂O and expiratory tidal volume (Vtexp) < 10 ml/kg while titrating PEEP and I : E ratio; FiO₂ was reduced to 60–70%; acceptable SaO₂ values were at 85%.

Results

Mean duration of MV was 18.7 ± 5.3 days. During controlled mechanical hypoventilation PIP and Vtexp decreased from 41 ± 0.7 to 32 ± 1 cmH₂O (P < 0.01), and from 11.6 ± 0.3 to 8.3 ± 0.4 ml/kg (P < 0.01), whereas arterial PCO₂ increased from 44 ± 2.2 to 74.4 ± 4.5 mmHg (P < 0.01). Pulmonary barotrauma resolved rapidly in five patients during controlled hypoventilation. However, two patients subsequently needed extracorporeal lung support because of progredient hypoxemia. All but one patient survived.

Conclusion

PHC offers an attractive alternative to conventional MV in paediatric patients with ARDS resulting in improved pulmonary recovery and decreased mortality.