Apneustic anesthesia ventilation improves pulmonary function in anesthetized bottlenose dolphins (Tursiops truncatus)

Area of Science:

• Marine Mammal Anesthesiology
• Comparative Respiratory Physiology
• Veterinary Critical Care

Background:

• Mechanical ventilation is essential for small cetacean anesthesia due to inadequate spontaneous gas exchange.
• Existing ventilation methods do not accommodate the unique intermittent breathing patterns of dolphins.
• Current techniques may negatively impact cetacean cardiopulmonary physiology.

Purpose of the Study:

• To compare the cardiopulmonary effects of controlled mechanical ventilation (CMV) and a novel apneustic anesthesia ventilation (AAV) in bottlenose dolphins (Tursiops truncatus).
• To assess how AAV, mimicking natural dolphin breathing, impacts respiratory and cardiovascular function during anesthesia.

Main Methods:

• A cross-over study design was employed with nine bottlenose dolphins undergoing anesthesia for dental procedures or bronchoscopy.
• Dolphins were ventilated with either AAV or CMV, with modes switched after 30 minutes.
• Key cardiopulmonary parameters including gas exchange, hemodynamics, and respiratory mechanics were measured.

Main Results:

• Apneustic anesthesia ventilation (AAV) resulted in higher arterial oxygen tension and mean airway pressure.
• AAV significantly reduced alveolar dead space ventilation and the alveolar-arterial oxygen difference.
• No statistically significant differences in cardiovascular performance were observed between AAV and CMV.

Conclusions:

• Apneustic anesthesia ventilation (AAV) improves ventilation and pulmonary function in anesthetized dolphins by simulating their natural respiratory pattern.
• AAV demonstrates a potential advantage over controlled mechanical ventilation (CMV) for cetacean anesthesia.
• Further research is recommended to explore neutral buoyancy and drug protocols to minimize hemodynamic support needs.