Abstract: Anaesthesia for the Laparoscopic Patient
Courtney Scales DipVN, NCert(Anaesth), RVN – Clinical Educator (Anaesthesia) Keith Simpson BVSc, MRCVS, MIET(Electronics) – Clinical Director
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Laparoscopic surgery is becoming more common in veterinary medicine for non-invasive procedures including ovariectomies, ovariohysterectomies and liver biopsies. This minimally invasive approach to surgery has many appeals including a lower risk of postoperative wound breakdown compared to patients with an open laparotomy surgical approach, reduced tissue trauma, smaller incision size and decreased handling of the gastrointestinal tract which leads to improved postoperative comfort and recovery times.
Benefits to the patient specifically related to anaesthesia and analgesia include a significant reduction in postoperative pain scores and an increase in activity when compared to the same procedure when performed with a midline laparotomy approach. Additionally, there is also a decrease in serum stress response markers and inflammatory mediators.
There are however specific challenges relating to anaesthesia in the laparoscopic patient due to the physiological impact that insufflating the abdomen has, which the veterinary team should be familiar with.
To decrease any negative influences that positioning, and the pneumoperitoneum have during the patient’s anaesthesia, such as hypotension, pneumothorax, air embolism and haemorrhage, the intrabdominal pressure should not exceed 15mmHg (20cmH2O).
Haemodynamic changes may be caused by the direct effect of carbon dioxide on the cardiovascular system and also indirectly through its sympathetic stimulation causing tachycardia, hypertension and cardiac arrhythmias.
There is both a chemical and mechanical impact on ventilation related to the pneumoperitoneum required for abdominal insufflation. An increase in minute volume may be required to aid in the removal of this excessive level of carbon dioxide. To reduce the risk of barotrauma by trying to increase the patient’s tidal volume, increasing the respiratory rate should be the first action, and then the airway pressure and/or tidal volume can then be increased if no improvement is seen.
Other physiological impacts include those on the renal, hepatic and neurological systems, as well as informed choices on the patient’s airway management and airway management.
It can be appreciated that insufflation of the abdomen during laparoscopy affects multiple physiological processes that the veterinary team should be aware of.