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Expiratory muscle activity in anesthetized children: Effect on the single breath technique
Author(s) -
Shulman David L.,
Volgyesi George A.,
Burrows Frederick A.,
Lerman Jerrold,
England Sandra J.
Publication year - 1989
Publication title -
pediatric pulmonology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.866
H-Index - 106
eISSN - 1099-0496
pISSN - 8755-6863
DOI - 10.1002/ppul.1950070206
Subject(s) - medicine , halothane , anesthesia , abdominal muscles , abdomen , abdominal surgery , electromyography , surgery , psychiatry
Abstract Phasic expiratory activity of the abdominal muscles occurs in adults during halothane anesthesia, but has not been demonstrated in children. If present, abdominal muscle activity would preclude the use of recently developed tests of respiratory mechanics in children during anesthesia. We therefore measured abdominal muscle activity throughout induction of anesthesia with halothane in 10 patients between 1.5 and 9.5 years of age, seven with normal respiratory function and three with chronic airway obstruction. During induction of anesthesia with halothane in N 2 O and oxygen, the abdominal wall electromyograph (a‐EMG) was continuously recorded from surface electrodes. At the same time, the expiratory time constant (τ a ) was measured using the single breath test (SBT). The patients were then paralyzed with succinyl choline, and the a‐EMG signal and expiratory time constant during paralysis (τ P ) were recorded. The raw a‐EMG signal and its moving time average were compared with the phase of respiration and with the end‐tidal fraction of halothane (Fe halo ), and the effect of abdominal muscle activity on τ a was noted. Of the 10 patients, 2 had no abdominal muscle activity at any time during induction. Of the remaining 8 patients, 3 had continuous abdominal muscle activity throughout induction, including one patient with asthma. In the remaining five patients, abdominal muscle activity was present during light halothane anesthesia and disappeared at increased Fe halo . When abdominal muscle activity was present, τ a was significantly less than τ ρ . It is concluded that abdominal muscle activity in expiration is undetectable during deep halothane anesthesia in most children. But abdominal muscle activity persists throughout halothane induction in some children, and, when this occurs, there is an apparent decrease in τ a , invalidating the SBT as a test of passive respiratory mechanics. Pediatr Pilmonol. 1989; 7:82–88 .