Learning objectives

• Describe the possible consequences of prolonged anesthesia
• Manage patients scheduled for prolonged anesthesia

Background

• Prolonged anesthesia is associated with an increased risk of postoperative complications
• Careful preparation, management, and attention to detail reduce these risks

Negative effects of prolonged anesthesia

• • Accumulation of anesthetic agents leads to delayed emergence, depending of the pharmacokinetics of the agent used (e.g., isuflurane>desflurane, fentanyl>remifentanil)
  • Potential toxicity of anesthetic agents
    • Degradation of inhalational agents by CO2 absorber may lead to accumulation of toxins (e.g., sevoflurane tp compound A)
    • Inorganic fluoride production from the hepatic metabolism of sevoflurane and enflurane may be nephrotoxic in patients with chronic renal impairment
    • Prolonged exposure to nitrous oxide may result in acute vitamin B12 deficiency with megaloblastic anemia and neurological deficit
  • Impairment of gas exchange and respiratory mechanics (hypoxemia and hypercarbia secondary to slowly developing dependent atelectasis
  • The effects of anesthetic agents on renal function can lead to water and salt retention
  • Disturbances in intermediary carbohydrate metabolism promote the development of metabolic acidosis
  • Retention of anesthetic agents in the body can lead to undesired effects postoperatively
  • Decreased carbohydrate metabolism results in intraoperative hyperglycemia
  • Problems with accurate fluid and electrolyte management
  • Inadvertent perioperative hypothermia can lead to:
    • Increased wound infection
    • Surgical bleeding
    • Impaired immune function
    • Increased incidence of myocardial ischemia and infarction
    • Malignant arrhythmias
    • Postoperative shivering
  • Prolonged immobility can lead to:
    • Increased risk of deep vein thrombosis
    • Nerve damage and pressure sores
    • Bilateral compartment syndrome
    • Rhabdomyolysis
    • Corneal damage if the eyes are left open
• Postoperative delirium
• Immunosuppression and increased susceptibility to infections
• Increased risk of human error due to fatigue

Management

Suggested reading

• Pollard BJ, Kitchen, G. Handbook of Clinical Anaesthesia. Fourth Edition. CRC Press. 2018. 978-1-4987-6289-2.
• Cheng H, Clymer JW, Po-Han Chen B, et al. Prolonged operative duration is associated with complications: a systematic review and meta-analysis. J Surg Res. 2018;229:134-144.

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