The effect of insufflation pressure on pulmonary mechanics in infants during laparoscopic surgical procedures.

BACKGROUND: Few studies have reported objective measurements of pulmonary changes under controlled conditions in infants undergoing laparoscopic procedures. We objectively measured the pulmonary effects of laparoscopically-induced pneumoperitoneum in infants less than 1 year of age undergoing surgical procedures under general anaesthesia.

METHODS: Nineteen ASA I-II patients less than 1 year of age were enrolled in this direct observational study. Anaesthetic technique included inhalation induction using sevoflurane/O2/air and neuromuscular blockade. Infants were ventilated using 10-15 ml.kg-1 tidal volume at a respiratory rate sufficient to achieve normocarbia [PECO2 4.6-5.8 kPa (35-45 mmHg)]. Opioids and regional anaesthesia techniques were used when appropriate. Peak inspiratory pressure (PIP), expiratory tidal volume (Vt), endtidal carbon dioxide concentration (PECO2) and dynamic compliance (COMPdyn) were recorded at baseline, 5, 10 mmHg and maximal insufflation pressure (Pmax). Pmax was limited to 12 mmHg for infants <5 kg, 15 mmHg for infants >5 kg. At steady state Pmax, ventilator changes were implemented to restore Vt and PECO2 to within 10% of baseline. Each patient served as his own control.

RESULTS: At Pmax, average PIP increased 18%, average Vt decreased 33%, average PECO2 concentration increased 13%, average COMPdyn decreased 48%; O2 saturation fell in 41% of patients. Twenty ventilator adjustments were required; one patient experienced no changes in measured pulmonary mechanics, requiring no ventilator changes.

CONCLUSIONS: Pulmonary mechanics in infants change significantly during laparoscopic CO2 pneumoperitoneum; the magnitude of change correlates directly with intraperitoneal pressure. Greater than 90% of infants required at least one ventilatory intervention to restore baseline Vt and PECO2.