Lung mechanics and pulmonary function testing in cetaceans.

Area of Science:

• Marine Mammal Physiology
• Comparative Respiratory Physiology
• Cetacean Biology

Background:

• Understanding the respiratory physiology of cetaceans is crucial for their health and conservation.
• Limited data exists on the dynamic respiratory mechanics and metabolic rates of bottlenose dolphins.

Purpose of the Study:

• To measure esophageal pressures, respiratory flow rates, and expired gases in bottlenose dolphins.
• To estimate dynamic specific lung compliance (sCL), oxygen consumption (V̇O2), and carbon dioxide production (V̇CO2).
• To provide novel data for cetacean respiratory physiology relevant to clinical medicine and conservation.

Main Methods:

• Utilized a custom-made respirometry system to measure esophageal pressures, respiratory flow rates, and expired O2 and CO2.
• Recorded data during voluntary breaths and maximal respiratory efforts (chuffs) in six adult bottlenose dolphins.
• Calculated dynamic specific lung compliance, V̇O2, and V̇CO2 from breath-by-breath measurements.

Main Results:

• Bottlenose dolphins can generate expiratory flow rates >130 L/s and inspiratory flow rates >30 L/s.
• Inspiration is active, while expiration is passive during voluntary breaths and active during maximal efforts.
• Average sCL was 0.31±0.04 cmH2O⁻¹, substantially higher than humans and pilot whales.
• Estimated V̇O2 and V̇CO2 were comparable to previous studies using conventional respirometry.

Conclusions:

• Bottlenose dolphins possess unique and robust respiratory mechanics.
• The high lung compliance suggests adaptations for aquatic respiration.
• This study provides valuable physiological data for dolphin health management and conservation strategies.