Sevoflurane Concentrations in Children

Protocol definition:

This study will not deviate from standard anesthetic management of children with the exception of recording the child's vital signs and anesthetic gas concentrations during the anesthetic induction.

Healthy children, 2-6 years of age, fasting and unmedicated scheduled to undergo minor elective surgery under general anesthesia at Oishei Children's Hospital in Buffalo, New York will be consented for this protocol by the principal investigator. Parents who speak English will be approached for consent; the formal hospital translator service will be used for those parents who do not speak English. The medical translator will translate the consent form for the parents.

Children will be selected for inclusion in this study from the elective surgery list. A total of 28 children of both sexes will be enrolled, 14 with each of the two workstations. We will strive to include the workstation in each operating room at least once in the study. The choice of anesthesia workstations, Drager Apollo or General Electric (GE) Ohmeda, is predetermined by the floor on which the surgery is planned. Drager Apollo workstations are deployed in each of the 7 pediatric operating rooms on the second floor at Oishei and GE Ohmeda workstations are deployed in each of the 5 pediatric operating rooms on the third floor at Oishei.

Once the standard anesthesia monitors are applied, the children will undergo a routine inhalational induction that begins with a mixture of 5 liters/minute nitrous oxide and 2 liters/minute oxygen. Once the end-tidal nitrous oxide concentration reaches 0.45, the sevoflurane vaporizer will be dialed to 8%. The inspired and expired concentrations of sevoflurane will be recorded at the designated times (see data collection sheet) for the first 10 minutes of anesthesia. All vital signs (oxygen saturation, end-tidal carbon dioxide tension, blood pressure and heart rate) will also be recorded.All unusual movements and airway responses will also be recorded and when they occurred (under Notes on the data collection form). At the conclusion of the 10 minutes of the induction, the airway will be secured with an airway device, the surgery will proceed as planned and the recording will cease. The study will be terminated.

The inspired and expired concentrations of Sevoflurane with the Drager Apollo and GE Ohmeda workstations over time will be summarized and displayed graphically. The maximum inspired concentrations of Sevoflurane during each induction with the two types of workstations will be compared using Student's t-test at a significance level of P<0.05.

Jerrold Lerman MD, FRCPC, FANZCA (Fellow of the Australian and New Zealand College of Anesthetists) July 11, 2024

Inclusion criteria

• scheduled for elective surgery under general anesthesia,
• American Society of Anesthesiologists physical status 1 or 2 fasted, unpremeditated

Exclusion criteria

• parents refuse consent
• presence of moderate or severe cardiorespiratory disease
• difficult airway
• malignant hyperthermia
• neuromuscular disorders
• obesity
• obstructive sleep apnea