Theoretical effect of hyperventilation on speed of recovery and risk of rehypnotization following recovery - a GasMan® simulation
Hyperventilation may be used to hasten recovery from general anesthesia with potent inhaled anesthetics. However, its effect may be less pronounced with the newer, less soluble agents, and it may result in rehypnotization if subsequent hypoventilation occurs because more residual anesthetic will be available in the body for redistribution to the central nervous system. We used GasMan® simulations to examine these issues.
One MAC of isoflurane, sevoflurane, or desflurane was administered to a fictitious 70 kg patient for 8 h with normoventilation (alveolar minute ventilation [VA] 5 L.min-1), resulting in full saturation of the vessel rich group (VRG) and >95% saturation of the muscle group. After 8 h, agent administration was stopped, and fresh gas flow was increased to 10 L.min-1 to avoid rebreathing. At that same time, we continued with one simulation where normoventilation was maintained, while in a second simulation hyperventilation was instituted (10 L.min-1). We determined the time needed for the partial pressure in the VRG (FVRG; representing the central nervous system) to reach 0.3 MAC (MACawake). After reaching MACawake in the VRG, several degrees of hypoventilation were instituted (VA of 2.5, 1.5, 1, and 0.5 L.min-1) to determine whether FVRG would increase above 0.3 MAC(= rehypnotization).
Time to reach 0.3 MAC in the VRG with normoventilation was 14 min 42 s with isoflurane, 9 min 12 s with sevoflurane, and 6 min 12 s with desflurane. Hyperventilation reduced these recovery times by 30, 18, and 13% for isoflurane, sevoflurane, and desflurane, respectively. Rehypnotization was observed with VA of 0.5 L.min-1 with desflurane, 0.5 and 1 L.min-1 with sevoflurane, and 0.5, 1, 1.5, and 2.5 L.min-1 with isoflurane. Only with isoflurane did initial hyperventilation slightly increase the risk of rehypnotization.
These GasMan® simulations confirm that the use of hyperventilation to hasten recovery is marginally beneficial with the newer, less soluble agents. In addition, subsequent hypoventilation results in rehypnotization only with more soluble agents, unless hypoventilation is severe. Also, initial hyperventilation does not increase the risk of rehypnotization with less soluble agents when subsequent hypoventilation occurs. Well-controlled clinical studies are required to validate these simulations.
- Vesely, A, Fisher, JA, Sasano, N, Preiss, D, Somogyi, R, El-Beheiry, H, Prabhu, A, Sasano, H (2003) Isocapnic hyperpnoea accelerates recovery from isoflurane anaesthesia. Br J Anaesth 91: pp. 787-792 CrossRef
- Sakata, DJ, Gopalakrishnan, NA, Orr, JA, White, J, Westenskow, DR (2007) Hypercapnic hyperventilation shortens emergence time from isoflurane anesthesia. Anesth Analg 104: pp. 587-591 CrossRef
- Sakata, DJ, Gopalakrishnan, NA, Orr, JA, White, JL, Westenskow, DR (2007) Rapid recovery from sevoflurane and desflurane with hypercapnia and hyperventilation. Anesth Analg 105: pp. 79-82 CrossRef
- Gopalakrishnan, N, Sakata, DJ, Orr, JA, McJames, S, Westenskow, DR (2007) Hypercapnia shortens emergence time from inhaled anesthesia in pigs. Anesth Analg 104: pp. 815-821 CrossRef
- Katznelson, R, Minkovich, L, Friedman, Z, Fedorko, L, Beattie, WS, Fisher, JA (2008) Accelerated recovery from sevoflurane anesthesia with isocapnic hyperpnoea. Anesth Analg 106: pp. 486-491 CrossRef
- Stoelting, RK, Eger, EI (1969) The effects of ventilation and anesthetic solubility on recovery from anesthesia: an in vivo and analog analysis before and after equilibrium. Anesthesiology 30: pp. 290-296 CrossRef
- Eger, EI Recovery from anesthesia. In: Eger, EI eds. (1974) Anesthetic Uptake and Action. Williams & Wilkins, Baltimore/London, pp. 228-248
- Philip, JH (1986) Gas Man®: an example of goal oriented computer-assisted teaching which results in learning. Int J Clin Monit Comp 3: pp. 165-173 CrossRef
- Bouillon, T, Shafer, S (2000) Hot air or full steam ahead? An empirical pharmacokinetic model of potent inhaled agents. Br J Anaesth 84: pp. 429-431 CrossRef
- Eger, EI, Shafer, SL (2005) Context-sensitive decrement times for inhaled anesthetics. Anesth Analg 101: pp. 688-696 CrossRef
- Hendrickx, JFA, Lemmens, HJM, Shafer, SL (2006) Do distribution volumes and clearances relate to tissue volumes and blood flows? A computer simulation. BMC Anesthesiol 6: pp. 7 CrossRef
- Severinghaus, JW Role of lung factors. In: Papper, E, Kitz, R eds. (1963) Uptake and distribution of anesthetic agents. McGraw-Hill, New York, pp. 59-71
- Leeson, S, Philip, JH (2009) Hypoventilation after inhalation anesthesia can cause reanesthetization [abstract]. Anesthesiology 111: pp. A79
- Eger, EI, Saidman, LJ (2005) Illustrations of inhaled anesthetic uptake, including intertissue diffusion to and from fat. Anesth Analg 100: pp. 1020-1033 CrossRef
- Knill, RL, Gelb, AW (1978) Ventilatory response to hypoxia and hypercapnia during halothane sedation and anesthesia in man. Anesthesiology 49: pp. 244-251 CrossRef
- Peyton, PJ, Chao, I, Weinberg, L, Robinson, GJB, thompson, BR (2011) Nitrous oxide diffusion and the second gas effect on emergence from anesthesia. Anesthesiology 114: pp. 596-602 CrossRef
- The pre-publication history for this paper can be accessed here:http://www.biomedcentral.com/1471-2253/12/22/prepub
- Theoretical effect of hyperventilation on speed of recovery and risk of rehypnotization following recovery - a GasMan® simulation
- Open Access
- Available under Open Access This content is freely available online to anyone, anywhere at any time.
- Online Date
- September 2012
- Online ISSN
- BioMed Central
- Additional Links
- Inhaled anesthetics
- Isocapnic hyperventilation
- Pharmacokinetic modelling
- Author Affiliations
- 1. Department of Anesthesiology, Feinberg School of Medicine, Northwestern University Medical School, 251 East Huron, Chicago, IL, 60611-3053, USA
- 3. Department of Anesthesiology, OLV Hospital, Moorselbaan 164, Aalst, 9300, Belgium
- 5. University of Maastricht, Maastricht, The Netherlands
- 2. Department of Anesthesiology, Sint-Jan Hospital, Kruidtuinlaan 32, Brussel, 1000, Belgium
- 4. Department of Anesthesiology, OLV Hospital, Moorselbaan 164, Aalst, 9300, Belgium