Anesthesia for laparoscopic procedures with pneumoperitoneum, e.g., hernia repair, cholecystectomy, colon surgery.

Laparoscopic surgery with pneumoperitoneum is performed under general anesthesia and controlled ventilation.

1. Aspects relevant for anesthesia in surgery under pneumoperitoneum

a) Rise in paCO2

b) Interference with respiratory mechanics

c) Interference with hemodynamics

d) Increased rate of postoperative nausea and vomiting (PONV)

 

a) Rise in paCO2

Since the body rapidly absorbs the CO2 instilled in the abdominal cavity, this will elevate the paCO2. The CO2 absorption rate depends on the intraabdominal pressure, area of absorption (peritoneum) and the perfusion of the peritoneum/wall of the peritoneal cavity. The higher the intraabdominal pressure the stronger the compression of the vessels, thereby decreasing the CO2 absorption. Therefore, bleeding off the CO2 at the end of the procedure will temporarily boost its absorption.

During surgery, the minute ventilation must be increased by about 20%, but rarely by up to 50%. The controlling parameter here is the end-expiratory CO2 concentration. In functionally impaired cardiac patients the pneumoperitoneum may severely depress their cardiac output. Since patient capacity for CO2 elimination is markedly impaired in these cases, the paCO2 will be significantly higher than might be expected by the end-expiratory CO2 concentration. In case of doubt, arterial blood gas analysis will settle the issue.

b) Interference with respiratory mechanics

The peritoneum displaces the diaphragm craniad and mechanically impedes respiration/ventilation. This effect may be reinforced by specific patient positioning maneuvers (e.g., Trendelenburg position in intestinal surgery). Similarly, intraperitoneal gas instillation and Trendelenburg positioning will diminish the FRC by about 40%. And the peak ventilation pressure will increase by about 40% as well. These conditions may displace the tracheal bifurcation craniad by 2 - 3 cm. Therefore, in dropping oxygen saturation consider tube dislocation with unilateral ventilation.

c) Interference with hemodynamics

The intraperitoneal pressure increase is paralleled by a decrease of about 20% in the venous return and cardiac output. At the same time the peripheral vascular resistance will increase. The increased intrathoracic pressure will also increase the vascular resistance in the lungs. In pneumoperitoneum, the heart rate will increase by about 10%. Peritoneal distention, particularly when the gas is just being instilled, may result in reflex vagotonia with bradycardia, particularly if anesthesia is shallow. Always keep atropine ready in these operations.

d) Increased rate of postoperative nausea and vomiting (PONV)

For laparoscopic surgery, the rate of postoperative nausea and vomiting (PONV) has been reported up to 50%. Prophylactic administration of 8 mg dexamethasone after induction and 0.625-1.25 mg DHB is recommended in patients so predisposed.

For laparoscopic surgery, some anesthesiologists recommend the insertion of a gastric tube after induction of anesthesia. During mask ventilation with accidental or unnoticed insufflation of air into the stomach, this is supposed to protect the stomach against injury when introducing the trocars and decrease the risk of aspiration during extubation.

2. Required

  • Detailed informed consent discussion
  • Physical examination and history, possibly resulting in additional studies
  • Patient informed consent

3. Workflow description

  • Device check by the nurse anesthetist
  • Nursing staff on ward premedicates patient with midazolam oral syrup at least 30 minutes before surgery is started.
  • Preoxygenate the patient with 100% oxygen
  • Respecting its time to onset administer the opioid (e.g., fentanyl, sufentanil)
  • Once the opioid effect has taken hold inject the hypnotic (e.g., propofol) until the blink reflex lapses
  • Bag-valve-mask ventilation, possibly with an oropharyngeal airway
  • Check BVM ventilation and relax patient
  • Open mouth and check teeth
  • Laryngoscopy and then intubate trachea under direct vision, if possible
  • Check black marking on tube
  • Block tube
  • Ventilate and auscultate
  • Secure tube and oropharyngeal airway with adhesive tape
  • Hook up patient to ventilator in the OR
  • Check capnometry
  • Adjust flow, FiO2 and concentration of anesthetic gas
  • Hook up patient to the monitor units
  • Position patient for surgery

 

 

4. Intraoperative monitoring

  • Single-channel ECG
  • NIBP
  • Pulse oximetry
  • Capnometry
  • Ventilation settings (pressure, volume)
  • Measure end-expiratory CO2 concentration
  • Measure inspiratory and expiratory concentration of oxygen and anesthetic gas
  • Neuromuscular monitoring
  • Temperature measurement (ear thermometer)

5. Emergence

  • Check retained relaxation
  • Check opiate overhang
  • Wash out anesthetic gas through high-flow setting
  • Prepare suction unit
  • Return patient to spontaneous respiration
  • Extubate in presence of protective reflexes
  • Oral or endotracheal suction
  • Observe patient's respiration after extubation
  • Hand over patient to recovery room

6. Recovery room

  • Hookup patient to monitor units (NIBP, pulse oximetry, ECG monitor)
  • Administer oxygen if needed
  • Obtain pain history and administer treatment
  • Order pain protocol for ward
  • Anesthesiologist discharges patient from recovery room

Author: Prof. Dieffenbach, MD Head, Department of Anesthesiology and Surgical Intensive Care

St. Kathrinen-Hospital Frechen GmbH, Germany