Influence of sepsis on sevoflurane minimum alveolar concentration in a porcine model
B Allaouchiche1, F Duflo, J P Tournadre
1Department of Anaesthesiology and Intensive Care, Hotel-Dieu Hospital, Lyon, France.
Abstract:
Sevoflurane is widely used in anaesthetic protocols for patients undergoing surgical procedures. However, there are no reports on the influence of sepsis on minimum alveolar concentration of sevoflurane (MAC(SEV)) in animals or in humans. The aim of this study was to test the hypothesis that sepsis could alter the MAC(SEV) in a normotensive septic pig model. Twenty young, healthy pigs were used. After they had received 10 mg kg(-1) of ketamine i.m. for premedication, anaesthesia was established with propofol 3 mg kg(-1) and the trachea was intubated. Sevoflurane was used as the sole anaesthetic agent. Baseline haemodynamic recording included electrocardiography, carotid artery blood pressure and a pulmonary thermodilution catheter. Baseline MAC(SEV) in each pig was evaluated by pinching with a haemostat applied for 1 min to a rear dewclaw. MAC(SEV) was determined using incremental changes in sevoflurane concentration until purposeful movement appeared. Pigs were assigned randomly to two groups: the saline group (n = 10) received a 1-h i.v. infusion of sterile saline solution while the sepsis group (n = 10) received a 1-h i.v. infusion of live Pseudomonas aeruginosa. Epinephrine and hydroxyethylstarch were used to maintain normotensive and normovolemic haemodynamic status. In both groups, MAC(SEV) was evaluated 5 h after infusion. Significant increases in mean artery pulmonary pressure, filling, epinephrine and vascular pulmonary resistances occurred in the sepsis group. MAC(SEV) for the saline group was 2.4% [95% confidence interval (CI) 2.1-2.55%] and the MAC(SEV) for the sepsis group was 1.35% (95% CI 1.2-1.45%, P<0.05). These data indicate that MAC(SEV) is significantly decreased in this normotensive septic pig model.
Insights
Sepsis significantly reduces the minimum alveolar concentration of sevoflurane (MAC(SEV)) in pigs. This finding is crucial for understanding anesthetic requirements during critical illness and sepsis.
Area of Science:
- Anesthesiology
- Critical Care Medicine
- Sepsis Research
Background:
- Sevoflurane is a common anesthetic agent used in surgical procedures.
- The impact of sepsis on the minimum alveolar concentration of sevoflurane (MAC(SEV)) remains largely uninvestigated in animal models and humans.
- Understanding anesthetic requirements during sepsis is critical for patient management.
Purpose of the Study:
- To investigate the effect of sepsis on MAC(SEV) in a normotensive pig model.
- To test the hypothesis that sepsis alters MAC(SEV).
Main Methods:
- Twenty healthy pigs were used, with anesthesia induced by ketamine and propofol.
- Baseline MAC(SEV) was determined using incremental sevoflurane concentrations.
- Pigs were randomly assigned to receive either a saline infusion or live Pseudomonas aeruginosa to induce sepsis; MAC(SEV) was re-evaluated 5 hours post-infusion.
Main Results:
- The sepsis group exhibited significant increases in mean pulmonary artery pressure and pulmonary vascular resistance.
- MAC(SEV) in the saline group was 2.4% (95% CI 2.1-2.55%).
- MAC(SEV) in the sepsis group was significantly decreased to 1.35% (95% CI 1.2-1.45%, P<0.05).
Conclusions:
- Sepsis significantly decreases the minimum alveolar concentration of sevoflurane in a normotensive pig model.
- These findings suggest altered anesthetic requirements in septic patients.
- Further research is warranted to elucidate the mechanisms behind this MAC(SEV) reduction in sepsis.
