How Young Is the Youngest Infant for Outpatient Surgery?

Overall Risk in Pediatric Anesthesia

Few studies specifically address risk in infants for outpatient surgery. Patel and Hannallah assessed anesthetic complications in a large series of pediatric outpatients and did not note any specific issues in approximately 350 patients younger than 6 months. Unanticipated admission is a surrogate for risk in ambulatory populations; a retrospective case-control study found an overall low rate of admission (0.97%) but identified age younger than 2 years as a predictive factor along with American Society of Anesthesiologists (ASA) stage 3, duration and time of surgery, presence of obstructive sleep apnea, and certain surgical specialties. Unfortunately the age group younger than 2 years was not further subdivided.

Further evaluation of overall risk requires extrapolation from studies of particular patient populations or from adverse outcomes in infants who are not necessarily outpatients. Several studies have demonstrated an increased incidence of complications in infants (<1 year) compared with other pediatric age groups. A prospective survey of 40,240 anesthetics in infants and children from 1978 to 1982 found an overall complication rate of 4.3% in infants compared with 0.5% in children 1 to 14 years of age; the cardiac arrest rate was 1.9% in infants compared with 0.2% in the older patients. Risk increased with increasing ASA status and in emergency procedures; the majority of “accidents” in the infant group occurred during the maintenance of anesthesia and were initiated by respiratory events. Analysis of anesthetics conducted in more than 29,000 children from 1982 to 1987 found a high incidence of adverse events in very small infants (younger than 1 month), but patients were more likely to have a higher ASA status or be undergoing major cardiac or intraabdominal surgery. A large prospective French audit reflecting currently available drugs and monitoring techniques showed that respiratory events accounted for 53% of all intraoperative events and that there remains a higher risk for adverse events in infants compared with older children.

Analysis of closed claims data as published in 1993 showed that pediatric claims were more often related to respiratory events and that the mortality rate was greater than in adults. The complications in pediatric cases were more frequently thought to have been preventable with better monitoring. Analysis of pediatric closed claims from 1990 to 2000 showed a decrease in the proportion of respiratory claims, particularly those for inadequate oxygenation and ventilation, compared with pediatric claims from the earlier period.

The initial observations from the closed claims data led to the creation of the Pediatric Perioperative Cardiac Arrest (POCA) Registry, which collected basic demographic information from participating institutions along with details of cardiac arrest cases. Although overall denominator data are available, more specific information such as breakdown of anesthetic agents in all cases or qualifications of the anesthesia caregivers is not. The incidence of cardiac arrest for the institutions studied for the first report (1994–1997) was 1.4 per 10,000 anesthetics, with a mortality rate of 26% after arrest. Cardiac arrest occurred most often in patients less than 1 year of age and in patients with severe underlying disease. Patients with concurrent diseases and those having emergency surgery were most likely to have fatal outcomes. In patients whose ASA status was 1 or 2, the majority of cardiac arrests were because of cardiovascular depression from halothane alone or in combination with other drugs; the second most common etiology was respiratory events. Cases from the POCA registry for the years 1998 to 2004 demonstrated a declining proportion of cardiac arrests related to medications, in parallel with the transition from halothane to sevoflurane in clinical practice.