Circulatory assist method and apparatus

An apparatus for improving the cardiac output of a patient said apparatus comprising:

• detection means for detecting the onset of ventricular ejection in the cardiac cycle of the patient;
• pressure increasing means including means for injecting a respiratory fluid into the patient's lungs for selectively increasing intrathoracic pressure of the patient;
• control means responsive to said detection means for activating said pressure increasing means in relative phase with respect to said ventricular ejection;
• cardiocirculatory monitoring means for continuously or periodically monitoring the patient's cardiac output on a breath by breath basis and for providing output signals indicative thereof;
• and
• delay means responsive to said output signals for delaying activation of said control means in response to said detecting means and for thereby repeatedly adjusting said relative phase of pressure increase to ventricular ejection so that said cardiac output is maximized by reducing ventricular afterload and maintaining ventricular preload.

An apparatus for improving the cardiac output of a patient, said apparatus comprising:

• detection means for detecting the onset of ventricular ejection in the cardiac cycle of the patient;
• continuously or periodically monitoring means for monitoring the patient's cardiac output on a breath by breath basis,
• pressure increasing means including means for injecting a respiratory fluid into the patient's lungs for selectively increasing intrathoracic pressure of the patient;
• and
• control means responsive to said detection means for activating said pressure increasing means in relative phase with respect to said ventricular ejection and for repeatedly adjusting said relative phase of pressure increase to ventricular ejection to maximize cardiac output by reducing ventricular afterload and maintaining ventricular preload.

An apparatus for improving the cardiac output of a patient, said apparatus comprising:

• detection means for detecting the onset of ventricular ejection in the cardiac cycle of the patient;
• pressure increasing means for selectively increasing, intrathoracic pressure of the patient;
• control means responsive to said detection means for activating said pressure increasing means in relative phase with respect to said ventricular ejection;
• cardiocirculatory monitoring means for ascertaining the extent of cardiac output improvement and for providing an output signal indicative thereof, said cardiocirculatory monitoring means including oxygen consumption monitoring means for determining the rate of oxygen consumption of the patient, and said oxygen consumption monitoring means comprising (i) means for supplying an oxygen stream to the patient, (ii) first concentration measuring means for measuring concentration of oxygen in said oxygen stream, (iii) second concentration measuring means for measuring concentration of oxygen in said stream at a point including gases exhausted by the patient, and (iv) flow measuring means for measuring the flow rate of gases in said stream, said cardiocirculatory monitoring means including calculating means responsive to said means (i)-(iv) for producing said output signal, and
• delay means responsive to said output signal, said delay means being for delaying activation of said control means in response to said detecting means so that said cardiac output is maximized.