Cardiac augmentation by phasic high intrathoracic pressure support in man

Area of Science:

• Cardiovascular Physiology
• Critical Care Medicine

Background:

• Intrathoracic pressure significantly impacts left ventricular performance.
• Sustained increases in intrathoracic pressure can decrease cardiac output by reducing venous return.
• Phasic increases in intrathoracic pressure, without reducing venous return, may improve cardiac output in ventricular failure.

Purpose of the Study:

• To investigate the cardiovascular effects of phasic high intrathoracic pressure support (PHIPS) in patients with refractory shock.
• To determine if PHIPS can improve cardiac output and left ventricular performance.

Main Methods:

• PHIPS was applied to seven patients in intensive care using abdominal and chest wall binding during positive-pressure ventilation.
• Cardiovascular parameters including esophageal pressure, mean arterial pressure, and cardiac output were measured before and during PHIPS.
• Gated cardiac blood pool scan was used in one patient to assess ejection fraction and end-diastolic volume.

Main Results:

• PHIPS increased esophageal pressure and mean arterial pressure.
• Cardiac output significantly increased from 3.6 to 4.2 L/min during PHIPS.
• Left ventricular filling pressures remained constant, and one patient showed improved ejection fraction and decreased end-diastolic volume.

Conclusions:

• PHIPS augments left ventricular performance by reducing left ventricular afterload.
• This method shows promise for improving cardiovascular function in patients with shock.
• Further research into PHIPS as a therapeutic strategy is warranted.