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Respiratory compliance during sedation, anesthesia, and paralysis in infants and young children
M E Fletcher1, C Stack, M Ewart
1Respiratory and Anaesthetic Unit, Institute of Child Health, London, United Kingdom.
Insights
Respiratory compliance significantly decreases in infants and young children after halothane anesthesia induction. This reduction in respiratory compliance (Crs) can be reversed with paralysis and manual ventilation at higher tidal volumes.
Area of Science:
- Anesthesiology
- Pediatric Pulmonology
- Respiratory Physiology
Background:
- Total respiratory compliance (Crs) reduction in adults during halothane anesthesia is known.
- Paired studies on Crs changes in children undergoing halothane anesthesia are lacking.
Purpose of the Study:
- To investigate the effect of halothane anesthesia induction on total respiratory compliance (Crs) in infants and young children.
- To explore methods for reversing anesthesia-induced Crs reduction in pediatric patients.
Main Methods:
- The multiple occlusion technique was employed to measure Crs in 17 infants and young children.
- Measurements were taken during sedated sleep (CrsS) and after halothane anesthesia induction (CrsA).
- Crs was also assessed in a paralyzed, anesthetized state with varying tidal volumes.
Main Results:
- Crs significantly decreased by a mean of 34.7% after halothane anesthesia induction.
- Anesthesia led to reduced tidal volume and increased respiratory frequency in all subjects.
- Reversing Crs reduction was achieved by paralysis and manual ventilation at tidal volumes similar to those during sedation.
Conclusions:
- Halothane anesthesia induction causes a significant fall in Crs in infants and young children.
- Manual ventilation with higher tidal volumes can reverse anesthesia-induced Crs reduction in pediatric patients.
- Tidal volume variations significantly influence Crs measurements in this population.
Abstract:
Although total respiratory compliance (Crs) has been shown to fall in adults on induction of halothane anesthesia, no successful paired studies have been reported in children. The multiple occlusion technique was used to measure Crs in 17 infants and young children during sedated sleep (CrsS) and shortly after, following induction of halothane anesthesia (CrsA). Crs fell in all but one infant after induction of anesthesia, with a mean fall of 34.7% (range 0-58%). This was accompanied by a reduction in tidal volume and increase in frequency in every case. In 7 of the 17 children, who were to be paralyzed for surgical purposes, Crs was also measured in this anesthetized-paralyzed state. When tidal volume administered during manual ventilation was similar to that observed during measurement of CrsA, Crs during this low-volume ventilation was similar to CrsA. When tidal volume was increased and Crs remeasured, there was a significant increase in every case, with the high-volume Crs within 10% of CrsS in all but one child, in whom there was a 31.4% increase with respect to CrsS. Changes in tidal volume accounted for approximately 50% of the variability in each state. These results demonstrate a highly significant fall in Crs in infants and young children after induction of halothane anesthesia. In addition it appears that this reduction in Crs can be reversed by paralyzing the child and manually ventilating with tidal volumes approximating those seen during sedation.