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General principles for laparoscopic surgery

General principles for laparoscopic surgery

Laparoscopic techniques have been developed for many operations including cholecystectomy, fundoplication, vagotomy, hemicolectomy, hernia repair, appendicectomy, and oesophagectomy.
Compared with laparotomy the major advantages are:
  • Reduced tissue trauma required for surgical exposure.
  • Reduced wound size and postoperative pain.
  • Improved postoperative respiratory function: Following open cholecystectomy FVC is reduced by approximately 50% and changes are still evident up to 72 h postoperatively. Following laparoscopic cholecystectomy FVC is reduced by approximately 30% and is normal at 24 h postoperatively.
  • Reduced postoperative ileus.
  • Earlier mobilization.
  • Shorter hospital stay.
Surgical requirements
  • Gravitational displacement of abdominal viscera from the operative site.
  • Decompression of abdominal viscera, especially the stomach (nasogastrictube) and bladder (urinary catheter). Prevents injury on trocar insertion.
  • Pneumoperitoneum. This separates the abdominal wall from the viscera. An intra-abdominal pressure of 15 mmHg is adequate for most procedures. Modern equipment has an automatic limit on abdominal pressure. Beware older equipment which may not have an automatic limit, as can deliver gas flows producing an intra-abdominal pressure greater than 40 mmHg.
  • Carbon dioxide can be used to create the pneumoperitoneum. This has the advantage of being non-combustible allowing the use of diathermy or laser. Disadvantages include systemic absorption and peritoneal irritation producing pain.
Intra-operative effects of laparoscopic surgery
  • Pneumoperitoneum raises intra-abdominal pressure. Physiological changes are minimized if the intra-abdominal pressure <15 mmHg. This value should be monitored on the insuflation equipment. Physiological effects include:
    Respiratory Diaphragmatic displacement, reduced lung volumes and compliance, increased airway resistance, increased V/Q mismatch, hypoxia/hypercapnia from hypoventilation, increased risk of regurgitation
    CVS Increased systemic vascular resistance, raised mean arterial pressure, compression of IVC, reduced venous return, reduced cardiac output
    Renal Reduced renal blood flow, reduced glomerular filtration rate, reduced urine output

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  • Patient positioning. With upper abdominal procedures the patient is placed head up (reverse Trendelenberg position). For lower abdominal procedures the patient is placed head down (Trendelenberg position). The usual tilt is 15–20 degrees. Some left tilt is usual with cholecystectomy. These postures may further stress CVS and respiratory function.
  • Systemic carbon dioxide absorption may produce hypercarbia and acidosis.
  • Extraperitoneal gas insuflation occurs through a misplaced trocar or when gas under pressure dissects through tissue defects. It may cause subcutaneous emphysema, pneumomediastinum, pneumopericardium, or pneumothorax.
  • Venous gas embolism may occur when the trocar is inadvertently positioned in a vessel. Presents as acute right heart failure, reduced ETCO2, arrhythmias, myocardial ischaemia, hypotension, elevated CVP.
  • Unintentional injuries to intra-abdominal structures—major vessels, viscera, liver, and spleen. May not be detected during surgery. Presents postoperatively with pain, hypotension, hypovolaemia, peritonitis, septicaemia.
Anaesthetic management
Preoperative
  • Contraindications to laparoscopic surgery are relative. Successful laparoscopic procedures have been carried out on patients who were anticoagulated, markedly obese, or pregnant.
  • Fit and young patients tolerate the physiological changes well.
  • Elderly patients and those with cardiac or pulmonary disease have more marked and varied responses.
  • NCEPOD 1996/1997 recommended caution in patients who were ASA >3, age >69 years, those who had a history of cardiac failure, and those with widespread ischaemic heart disease.
  • Patients with marked respiratory or cardiac disease must be thoroughly reviewed and optimized preoperatively and have a surgeon experienced in the procedure as the operator. Beware of patients being admitted on the day of surgery without the appropriate preoperative preparation.
  • Prescribe paracetamol 1 g PO and an NSAID, e.g. diclofenac 50>100 mg PO, 2 h preoperatively.
  • Be prepared to convert to an open procedure (1–7%).
Perioperative
  • General anaesthesia with endotracheal intubation to protect against pulmonary aspiration, aids ventilation and allows IPPV. Use IPPV to overcome the respiratory effects of pneumonperitoneum and hypercarbia. Good muscle relaxation reduces the intra-abdominal pressure needed for adequate surgical exposure. Monitor relaxants.
  • Induction: avoid excess stomach inflation from mask ventilation.
  • Nasogastric tube: insert and aspirate. This deflates the stomach reducing the risk of gastric injury during trocar insertion and improves surgical exposure.
  • Use a urinary catheter for lower abdominal procedures. This decompresses the bladder and reduces the risk of injury.
  • Ventilate to normocarbia. Raised intra-abdominal pressure and systemic absorption of carbon dioxide will require increased minute volume and raised airway pressures.

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  • Watch for inadvertent endobronchial intubation if the patient is positioned head down with pnuemoperitoneum.
  • Opioids: short acting opioids, e.g. fentanyl, alfentanil, can be used intraoperatively to cover what can be an intense but short-lived stimulus.
  • Nitrous oxide: concerns regarding problems with bowel distension and postoperative nausea and vomiting have not been substantiated.
  • Volatiles: avoid halothane—sensitized myocardium in the presence of hypercarbia—because of a risk of arrhythmias.
  • Fluids: avoid hypovolaemia as this exaggerates the deleterious CVS effects of the procedure.
  • Gas insuflation into the peritoneal cavity with stretching of the peritoneum, raised intra-abdominal pressure and altered patient positioning can cause a range of clinical responses:
    • Sympathetic response: hypertensive, tachycardia, increased cardiac output is the most common response. Treatment: increase volatiles, shortacting opioid, e.g. alfentanil, remifentanil, vasodilator, and/or beta-blocker.
    • CVS depression with a fall in cardiac output: hypotension, tachycardia, or bradycardia. Treatment: fluids, vasodilators, inotropes.
    • Vagal response: asystole, sinus bradycardia, nodal rhythm, hypotension. Treatment: vagolytics.
  • If there is intra-operative hypoxia consider:
    • Hypoventilation—pneumoperitoneum, position, inadequate ventilation.
    • V/Q mismatch—reduced FRC, atelectasis, endobronchial intubation, extraperitoneal gas insuflation, bowel distension, pulmonary aspiration, and rarely pneumothorax.
    • Reduced cardiac output—IVC compression, arrhythmias, haemorrhage, myocardial depression, venous gas embolism, extraperitoneal gas.
  • Subcutaneous emphysema during the procedure spells DANGER—stop gas insuflation and check for extraperitoneal gas insuflation.
  • At end of operation encourage the surgeon to expel as much CO2 as possible to reduce pain. Local anaesthetic to wound sites.
  • For laparoscopic cholecystectomy remove the nasogastric tube before taking the patient to recovery. For other procedures check with the surgeon.
Postoperatively
  • Pain varies significantly and is worst in the first few hours postoperatively. It ranges from shoulder tip pain (diaphragmatic irritation) to deep-seated pain from the surgery. Significant pain extending beyond the first day raises the possibility of intra-abdominal problems.
  • Prescribe regular paracetamol and NSAIDs with opioid PRN.
  • Nausea and vomiting: over 50% of patients require antiemetics. Give intraoperatively and prescribe postoperatively.
Special considerations
  • Intra-operative monitoring: standard monitoring including nerve stimulator. Respiratory monitoring is essential including ETCO2 and airway pressure. In patients with severe cardiopulmonary compromise use intraarterial blood pressure and CVP monitoring.

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  • LMA: some anaesthetists use an LMA for laparoscopic procedures. This is an individual choice. Potential contraindications to its use are an inexperienced surgeon, an anticipated difficult procedure, obesity, history of reflux, and pre-existing severe cardiopulmonary compromise.
  • Some short procedures (e.g. laparoscopic sterilization) can be performed without muscle relaxation provided that the operator is experienced.
  • Regional anaesthesia is not generally used as the sole anaesthetic technique because of the level of block required, pneumoperitoneum, patient positioning and shoulder tip pain.
  • Mortality/morbidity: the incidence of adverse events is approximately 5%. The most common complication is superficial infection at the site of the umbilical trocar. There are a number of case reports describing acute hypotension, hypoxia, and cardiovascular collapse with laparoscopic surgery. The cause is probably multifactorial. Be prepared to convert to an open procedure if the patient is too unstable.
  • Open versus laparoscopic procedures: in the case of cholecystectomy the laparoscopic technique, unless surgically impossible, is the technique of choice even in high-risk patients because of postoperative advantages. Mortality following open cholecystectomy overall is less than 1% but in the elderly population can be up to 10%. The adverse event rate following open cholecystectomy is approximately 20%. For other procedures little good evidence exists.
  • Laparoscopic appendicectomy: not recommended if perforated appendix is suspected. It has the advantage of allowing diagnosis and preventing unnecessary laparotomy in 20% of cases. Potential advantages are a better cosmetic result, reduced wound pain, and a more rapid return to normal activities, but these are not proven. Risks of laparoscopic appendicectomy are pneumoperitoneum and prolonged surgery; it is also more expensive.
  • Laproscopic inguinal hernia: more applicable for indirect hernias. Direct hernias are more challenging. High-risk cases are best done open under local anaesthetic. There are no clear postoperative advantages, with the total length of incisions essentially the same for the two procedures. The laparoscopic technique has disadvantages associated with a GA and pneumoperitonuem.
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