When planning for laparoscopy, have you ever thought about its impact on your patients’ ability to tolerate general anaesthesia? The key to success, as always, is preparation and vigilant monitoring.
The abdominal insufflation required during laparoscopy will impact on both the pulmonary and cardiovascular systems. Understanding the changes that occur when the abdomen is insufflated will help you plan appropriate ventilation strategies. This, along with considering the primary presenting disease and any co-morbidities, will help set you up for success.
This blog will discuss the impact laparoscopy has on pulmonary physiology. A subsequent blog will discuss some possible ventilation management strategies.
When laparoscopy is performed gas is used to insufflate the abdomen to a pressure of up to 15 mmHg. The resulting significantly increased abdominal pressure limits normal movement of the diaphragm. Lung tissue becomes less compliant, tidal volume decreases and there is a decreased lung functional residual capacity. This results in a significant decrease in gas exchange throughout the respiratory cycle. Insufflation may also lead to a mismatch in ventilation/perfusion, where deoxygenated blood is carried back to the arterial side of the circulation, causing a reduction in delivery of oxygen to the tissues. Bottom line the greater the insufflation pressure the greater the impact on pulmonary physiology.
In spontaneously breathing patients, the reduction in tidal volume results in significant hypoventilation, and respiratory muscle fatigue can occur when breathing against an expanded abdomen. This leads to an increase in end-tidal carbon dioxide (ETCO2). This increase is further exacerbated by the fact that carbon dioxide (CO2), a highly diffusible gas, is the most commonly used insufflation gas. CO2 will enter the blood stream contributing to the rise in arterial CO2 (PaCO2) and ETCO2.
High ETCO2 leads to a respiratory acidosis, which drives down body pH, leading to an acidaemia and a significant disruption to cellular metabolic processes within the body. If the patient is already vulnerable due to an established disease process then this will only exacerbate the situation, increasing the risk of anaesthesia and potentially exposing the patient to a poor outcome.
Next week we’ll discuss some strategies for managing ventilation of patients during laparoscopy.
If you want to learn more about Laparoscopy this is the workshop you don’t want to miss! Dr Brenton Chambers, Dr Peter Delisser & Dr Kathryn Duncan are combining their expertise and we’re keen to share it with you. This workshop is proving to be very popular so don’t delay! Register HERE for the Laparoscopy: Principles and Practice Workshop at Gatton on February 7-9, 2020.
Other interesting reads:
Part 2: Anaesthetic considerations during Laparoscopy
From Laparoscopy to surgery on large land-based predators (Dr Brenton Chambers)
A peek into Laparoscopy with Dr Peter Delisser
Dr Kathryn Duncan joins the laparoscopy educator team
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