Anaphylaxis in the monkey: hemodynamics and blood flow distribution

Area of Science:

• Cardiovascular Physiology
• Immunology
• Primate Models

Background:

• Anaphylaxis can lead to severe circulatory compromise.
• Understanding hemodynamic changes during anaphylaxis is crucial for effective treatment.

Purpose of the Study:

• To investigate the hemodynamic, blood flow distribution, and myocardial performance changes during induced anaphylaxis in non-human primates.
• To elucidate the primary causes of circulatory shock in this model.

Main Methods:

• Ovalbumin-sensitized monkeys (Macaca irus) were challenged to induce anaphylaxis.
• Hemodynamic parameters, regional blood flow, and myocardial function were monitored.
• Pulmonary and systemic vascular resistance, cardiac output, and ventricular performance were assessed.

Main Results:

• Anaphylaxis induced severe circulatory shock with decreased systemic and left atrial pressures, and increased pulmonary and right atrial pressures.
• Pulmonary vascular resistance increased tenfold, markedly reducing cardiac output (-75%).
• Blood flow redistributed to vital organs (brain, heart, liver) at the expense of other regions; myocardial flow also redistributed, leading to reduced right and left ventricular stroke work.

Conclusions:

• Increased pulmonary vascular resistance is the initial cause of low outflow state in anaphylaxis.
• Acute right heart failure follows, contributing significantly to the shock state.
• Hemodynamic and myocardial dysfunction are key features of severe anaphylaxis.