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[Diaphragmatic fatigue in hypovolemic shock]
1Instituto de Investigaciones Médicas Alfredo Lanari, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
Medicina
|January 1, 1990
Summary
In hemorrhagic shock, diaphragmatic fatigue develops, impairing respiratory compensation. Mechanical ventilation may influence respiratory muscle activity during shock.
Area of Science:
- Physiology
- Respiratory Medicine
- Critical Care
Background:
- Hemorrhagic shock leads to complex physiological responses.
- Understanding diaphragmatic function is crucial in critical illness.
Purpose of the Study:
- Investigate central respiratory response during hemorrhagic shock.
- Determine the development of diaphragmatic fatigue (FD).
- Assess the impact of mechanical ventilation on respiratory muscles in shock.
Main Methods:
- Developed a canine model of hemorrhagic shock (MAP 40 mmHg).
- Measured transdiaphragmatic pressure (Pdi), diaphragmatic electrical activity (Edi), and tracheal occlusion pressure (P0.1).
- Assessed diaphragmatic function via Pdi/Frequency and Pdi/Edi curves, with phrenic nerve stimulation.
Main Results:
- Initially compensated metabolic acidosis with hyperventilation and increased respiratory drive.
- Diaphragmatic fatigue (FD) developed, leading to mixed acidosis and decreased Pdi/Frequency and Pdi/Edi.
- Central respiratory drive (Edi.Ti.Fr) initially increased then decreased during FD, remaining above baseline.
Conclusions:
- Hemorrhagic shock induces diaphragmatic fatigue, compromising respiratory compensation.
- Mechanical ventilation's role in suppressing spontaneous respiratory activity warrants further investigation in shock states.