The trachea in the giraffe is long but narrow and dead space ventilation is in general considered to be of similar size as in other mammals. Less is known about matching of ventilation and lung blood flow. The lungs are large, up to 1 m high and 0.7 m wide, that may cause considerable ventilation/perfusion (VA/Q) mis-match by the influence of gravitational forces, leading to hypoxemia. We studied a young giraffe under anesthesia utilizing multiple inert gas elimination technique to analyze VA/Q distribution and arterial oxygenation and compared the results with other species of different sizes, including man. The VA/Q distribution was broad but unimodal and shunt, i.e blood flow through non-ventilated lung regions, was essentially absent, suggesting no lung collapse. The VA/Q match was as good as in similarly sized horse and was even comparable to that of smaller sized animals, including rabbit and rat. The match was also similar to that in anesthetized man. Arterial oxygenation was essentially similar in all studied species. The findings suggest that the efficiency of ventilation-perfusion matching is independent of lung size in mammals that vary in weight from less than one to more than 400 kg.
- gas exchange
- lung size
- Copyright © 2016, Journal of Applied Physiology