Physiology And Anesthetic Considerations

Although there was initial concern regarding the impact of pneumoperitoneum on pediatric cardiorespiratory physiology, the clinical effects appear to be limited. It is rare that any child has significant adverse response to the pneumoperitoneum. Several studies of the anesthetic response of children to laparoscopic procedures have been published demonstrating detectable differences, which do not have major clinical significance (21-25). They do serve to alert the surgeon and anesthesiologist to the potential for problems in the compromised child. Due to the effects of a pneumoperi-toneum, it can be anticipated that children with a smaller than normal functional reserve of pulmonary function may have difficulty maintaining oxygenation with increased intra-abdominal pressures. Neonates have relatively less reserve and may have more significant alterations in cardiorespiratory function with a pneumoperi-toneum, as well as greater CO2 absorption (26). We have seen this in a few patients with restrictive pulmonary conditions. In general these alterations may be corrected with reduced intra-abdominal pressures. Cardiac function has not been markedly altered and in some cases this has been examined with transesophageal echocardiogra-phy for follow-up of congenital cardiac disease.

It should be anticipated that certain children would have reduced oxygenation with increased intra-abdominal pressures, including those with restrictive pulmonary conditions, smaller infants or premature infants.

To some degree these children can be managed with increased minute ventilation, but that alone may not be sufficient and reduced intra-abdominal pressures are probably the best initial measure. We have never had to convert a laparoscopic case due to anesthetic conditions.

There was much concern about the effect of laparoscopy on the child's temperature, yet for renal and bladder surgery this has not been a concern (27). Indeed, in infants, we have noted a small but measurable degree of hyperthermia during nephrectomy. The etiology of this is uncertain, but the anticipated hypothermia has not been seen. Anesthesiologists should be informed not to expect significant reductions in body temperature. It is prudent to be prepared to warm the child with the various warming devices available, however, in case the procedure is prolonged or complex and there is loss of body temperature.

Reduced urine output during pneumoperitoneum is well recognized (28) and occurs in children. The actual physiology remains incompletely defined and while direct pressure effects have been postulated (29), there is evidence of a more complex mechanism as well (30). The effect is rapidly reversible and we have not seen adverse clinical outcomes. The anesthesia team needs to be informed so as to anticipate this occurrence and not respond by overhydrating the child. As more complex patients are undergoing laparoscopic procedures, the question of the effect of pneumoperitoneum-induced oliguria on already reduced renal function was raised. In experimental studies this did not appear to further injure renal function (30) and we have not identified this in clinical practice.

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