Obesity prolongs induction times in reptiles

Area of Science:

• Veterinary Anesthesiology
• Reptile Physiology
• Comparative Medicine

Background:

• Obesity is prevalent in pet and research reptiles.
• Inhalation anaesthesia in reptiles presents challenges due to slow metabolism and potential for anaesthetic accumulation in adipose tissue.
• Cardiac shunting can further complicate anaesthetic uptake and elimination.

Purpose of the Study:

• To investigate the impact of obesity on induction and recovery times from inhaled anaesthesia in reptiles.
• To model the temporal changes in isoflurane partial pressure in different tissues.
• To assess the combined effects of obesity and right-to-left cardiac shunting on anaesthetic dynamics.

Main Methods:

• A multi-compartment model was used to predict isoflurane partial pressure changes in various tissues.
• The model incorporated parameters for obesity and right-to-left cardiac shunting.
• Simulations evaluated the time to reach 90% brain anaesthetic equilibration (T90) and mean anaesthetic concentration.

Main Results:

• Obesity markedly increased T90 in both non-shunting (lean 47 min vs. obese >100 min) and shunting (lean 81 min vs. obese >100 min) reptiles.
• The combination of obesity and shunting doubled the time to achieve target anaesthetic concentration (8 min to 19 min).
• Adipose blood flow influenced induction time, with low flow diminishing the impact of obesity.

Conclusions:

• Obese reptiles experience significantly prolonged anaesthetic induction times, necessitating careful consideration during surgical procedures.
• The synergistic effect of obesity and cardiac shunting further delays anaesthetic equilibration.
• Further research is needed to determine the impact of obesity on anaesthetic recovery in reptiles, as T90 was not reached within the study's simulation timeframe.