Cardiovascular and pulmonary responses to increased acceleration forces during rest and exercise.

Background: The reduced cardiac output (CO) secondary to increased acceleration forces (+Gz) has applicability to daily life and pathophysiology. Increased +Gz and reduced CO affect the lung, resulting in reduced oxygen transport. A variety of studies have examined tolerance to high +Gz.

Hypoxia due to shunts in pig lung treated with O2 and fluorocarbon-derived intravascular microbubbles.

Rationale: Earlier work has shown that experimental conditions calling for improved tissue oxygenation could be assisted by i.v. infusion of a dodecafluoropentane emulsion (DDFPe) forming oxygen-transporting microbubbles.

Estimating the effect of lung collapse and pulmonary shunt on gas exchange during breath-hold diving: the Scholander and Kooyman legacy.

We developed a mathematical model to investigate the effect of lung compression and collapse (pulmonary shunt) on the uptake and removal of O(2), CO(2) and N(2) in blood and tissue of breath-hold diving mammals. We investigated the consequences of pressure (diving depth) and respiratory volume on pulmonary shunt and gas exchange as pressure compressed the alveoli. The model showed good agreement with previous studies of measured arterial O(2) tensions (Pa(O)(2)) from freely diving Weddell seals and measured arterial and venous N(2) tensions from captive elephant seals compressed in a hyperbaric chamber.

Deep diving mammals: Dive behavior and circulatory adjustments contribute to bends avoidance.

A mathematical model was created that predicted blood and tissue N(2) tension (P(N2)) during breath-hold diving. Measured muscle P(N2) from the bottlenose dolphin after diving repeatedly to 100 m (Tursiops truncatus [Ridgway and Howard, 1979, Science, 4423, 1182-1183]) was compared with predictions from the model. Lung collapse was modelled as a 100% pulmonary shunt which yielded tissue P(N2) similar to those reported for the dolphin.

Tissue nitrogen elimination in oxygen-breathing pigs is enhanced by fluorocarbon-derived intravascular micro-bubbles.

Unlabelled: The present study tested the hypothesis that intravascular micro bubbles generated by i.v. infusion of a 2 % dodecafluoropentane (DDFP) emulsion will enhance tissue denitrogenation during oxygen breathing.