What happens to mean arterial pressure and systemic vascular resistance during CO2 (carbon dioxide) pneumoperitoneum?

Hemodynamic Changes During CO2 Pneumoperitoneum

During CO2 pneumoperitoneum, mean arterial pressure increases and systemic vascular resistance increases, while cardiac output typically decreases due to reduced venous return. 1, 2

Cardiovascular Effects of CO2 Pneumoperitoneum

Mean Arterial Pressure (MAP)

• CO2 pneumoperitoneum causes an increase in mean arterial pressure due to increased intra-abdominal pressure and systemic absorption of CO2 1
• This increase in MAP is consistently observed across multiple studies and is a direct physiological response to the increased intra-abdominal pressure 2
• The elevation in MAP occurs despite a reduction in cardiac output, highlighting the significant increase in systemic vascular resistance 3

Systemic Vascular Resistance (SVR)

• Systemic vascular resistance significantly increases during CO2 pneumoperitoneum 1, 2
• This increase in SVR is a compensatory mechanism to maintain adequate perfusion pressure despite reduced venous return 4
• The elevation in SVR is more pronounced with higher intra-abdominal pressures (e.g., 20 mmHg versus 12 mmHg) 4

Cardiac Output and Preload

• Cardiac output typically decreases during CO2 pneumoperitoneum due to reduced venous return 2, 3
• The reduction in venous return is caused by compression of the inferior vena cava by the increased intra-abdominal pressure 1
• At moderate insufflation pressures (12 mmHg), some studies show minimal impact on stroke volume with adequate fluid management 4
• At higher insufflation pressures (20 mmHg), there is a more significant reduction in stroke volume and cardiac output 4

Positional Effects and Pneumoperitoneum

• Trendelenburg position (head down) during laparoscopy further increases mean arterial pressure, central venous pressure, mean pulmonary artery pressure, pulmonary capillary wedge pressure, and systemic vascular resistance 1
• The reverse Trendelenburg position combined with pneumoperitoneum causes a decrease in intrathoracic blood volume and pulmonary blood volume 5
• Position changes can either mitigate or exacerbate the hemodynamic effects of pneumoperitoneum 1, 5

Clinical Implications

• The hemodynamic changes during CO2 pneumoperitoneum can impair cardiac function, particularly in patients with pre-existing cardiovascular disease 1
• Patients with heart failure are at particular risk during laparoscopic procedures due to the combined effects of increased afterload and decreased preload 1
• Compared to open surgery, laparoscopic procedures do not reduce cardiac risk in patients with heart failure 1
• Careful hemodynamic monitoring is essential during laparoscopic procedures, especially in patients with compromised cardiovascular function 1

Special Considerations

Pregnancy

• In pregnant patients, the physiological effects of pneumoperitoneum are compounded by pregnancy-related cardiovascular changes 1
• The enlarging uterus already produces increased afterload through compression of the aorta and decreased cardiac return through compression of the inferior vena cava 1
• Pneumoperitoneum further exacerbates these effects, potentially compromising uteroplacental perfusion 1

Alternative Approaches

• Abdominal wall lift (gasless) techniques for laparoscopy show different hemodynamic profiles compared to CO2 pneumoperitoneum 3
• With abdominal wall lift, cardiac index and stroke volume increase while cardiac filling pressures and SVR remain unchanged, in contrast to the effects seen with pneumoperitoneum 3

In conclusion, CO2 pneumoperitoneum causes significant hemodynamic changes characterized by increased mean arterial pressure, increased systemic vascular resistance, and typically decreased cardiac output. These effects should be carefully considered when performing laparoscopic procedures, particularly in patients with compromised cardiovascular function.