Laproscopic surgery

Question 1

What are the cardiovascular effects of pneumoperitoneum?

Answer 1

Vagal stimulation

• abdominal insufflation stretches out the peritoneum which increases vagal tone and can lead to bradyarrhythmia
• many cardiac patients are prescribed b blockers, which increase the risk for bradyarrhythmia

Venous return

• initial increase in venous return (secondary to compression of the splanchnic vasculature which shifts blood volume into the central venous system) –> early rise in CO
• IAP rises (venous return to the heart decrease secondary to IVC compression and pooling of venous blood in the lower extremities) –> venous return and CO levels decrease

Chemical effects of CO2

• systemic vasodilation -> venous return drops
• arrhythmias –> poor cardiac output
• myocardial depression

Question 2

How can one attenuate the vagal response to abdominal insufflation

Answer 2

slower insufflations, lower IAP and premedication with glycopyrrolate can attenuate vagal response

Question 3

What are the respiratory effects of pneumoperitoneum?

Answer 3

Hypoxemia

• Increased IAP –> upward diaphragmatic displacement
• decrease in functional residual capacity –> V/Q mismatch –> PaO2 drops
• decrease in respiratory compliance –> ventilatory pressures increase

Hypercarbia

• increased PaCO2 due to absorption
• need to increase minute ventilation to promote CO2 exhalation

Question 4

What is the risk factors for development of subcutaneous emphysema?

Answer 4

• Prolonged surgery > 3,5 hours
• IAP > 15mmHg
• Placement of cannulas outside the peritoneal cavity
• Disruption of fascial planes
• High gas flow rates

Question 5

What are the effects of laparoscopic surgery?

Answer 5

• direct compression of renal vasculature, ureters and kidneys can lead to a reduction in renal blood flow, glomerular filtration rate, and oliguria
• a reduction in renal blood flow, secondary to mechanic compression of renal arteries from increased IAP and a decrease in cardiac output, stimulates renin release.

Question 6

How does laparoscopic surgery affect patients with poor cardiac function?

Answer 6

• increased afterload and decreases CO: accentuated or attenuated by intraoperative patient positioning, drugs and intravascular fluid status

In patients with decreased contractile reserve, congestive heart failure can be precipitated by increases in IAP, which increase preload (in the initial phase) and afterload (SVR).

Increases in myocardial oxygen demand, can be amplified during laproscopic surgery secondary to increases in HR, MAP, and afterload

Question 7

How does laparoscopic surgery affect patients with morbid obesity?

Answer 7

Respiratory effects of iatrogenic pneumoperitoneum are especially accentuated in the morbidly obese which may lead to increased incidences of hypoxemia, hypercarbia, raised ventilatory pressures

Morbid obesity also associated with OSA, 2’ pulmonary HT or even cor pulmonale

Possibly more prone to positioning injuries