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You are in Home >> Exams >> Mitchell Anaesthetic Notes


Upper GI Anaesthesia

Created: 21/8/2006
Updated: 8/1/2007
 

Management of a 60-year-old for laparoscopic cholecystectomy

  • Laparoscopy
    • Intraperitoneal insufflation with gas through a paraumbilical Veress needle
    • Pressure 12-15 mmHg
    • Usually CO2 used
  • Surgery
    • Elective, moderate risk
  • Preoperative
    • Assessment
      • Routine, plus
      • Respiratory compromise: lung disease, obesity, smoking
      • Reflux risk, airway assessment, assess need for RSI
      • Cardiac function
      • Autonomic dysfunction, e.g. diabetes
    • Premedication
      • H2 antagonist, anxiolytic
  • Intraoperative
    • Monitoring
      • Routine: SpO2, ECG, NIBP, gas analysis
      • Arterial line if very obese
      • Large IV
    • Induction
      • Routine IV induction, balanced technique unless RSI indicated
    • Maintenance
      • Volatile, O2, air or N2O
      • N2O may worsen complications of gas embolus
      • Narcotic analgesia, local anaesthetic in port sites
      • High PIP may be required during pneumoperitoneum
      • High degree of vigilance for signs of gas embolism
    • Complications
      • Trocar insertion and insufflation
        • Injury to bowel, bladder, large vessels
        • Insufflation of CO2 intravascularly
      • Pneumoperitoneum
        • CO2 absorption
        • Fall in cardiac output
        • Difficulty in ventilation
      • Usual surgical risks
        • Haemorrhage, bile leak, damage to nearby structures
        • Change to open procedure
    • Emergence
      • Routine, extubation in lateral position
  • Postoperative
    • Analgesia
      • Local, oral agents, IM narcotic
      • Consider epidural if opened
    • Ward level of care

Outline basic management of liver transplant surgery

  • Surgery
    • High risk, semi-urgent procedure
    • Requires tertiary hospital with special expertise
  • Issues
    • Perioperative management of hepatic failure
    • Coagulopathy and potential for haemorrhage
    • Massive transfusion and fluid requirements
    • Hypothermia, hyperkalaemia, acidosis
    • Often paediatric patient
    • Prolonged anaesthesia
  • Preoperative
    • Assessment
      • Complications of liver failure
        • Electrolyte, acid base, glucose, fluid homeostasis disordered
        • Coagulopathy
        • Encephalopathy
      • Other complications of primary cause of liver failure
        • Blood-borne virus, haemochromatosis (diabetes)
        • Crigler-Najjar syndrome (avoid barbiturates)
        • Budd-Chiari syndrome (may need anticoagulant prophylaxis)
        • Drug toxicity
    • Premedication
      • Aspiration prophylaxis, no sedation with encephalopathy
    • Transport
      • May be coming from ICU
    • Monitoring and access
      • Emergency drugs drawn up
      • Rapid infusor, cell saver, blood warmer, humidifier, patient warmer prepared
      • Large bore IV access x 2, PA catheter, arterial line
      • Thromboelastograph
    • Induction
      • Increased risk of aspiration with ascites, risk of haematemesis, delayed gastric emptying may require RSI or FOB
    • Positioning
      • Care for pressure areas, prolonged laparotomy
    • Maintenance
      • Relaxant GA, balanced technique
      • Air:oxygen:isoflurane does not compromise splanchnic blood flow
      • N2O avoided as it worsens bowel distension and gas emboli
      • Increased dose requirement but prolonged action from NDB
    • Preanhepatic phase
      • Major risks are haemorrhage and coagulopathy
      • Oliguria treated with adequate filling, diuretic, dopamine
    • Anhepatic phase (hours)
      • Portal vein, IVC, hepatic artery clamped, biliary drain
      • Diaphragm retracted: impairs venous return, reduces lung compliance
      • Renal venous congestion, oliguria
      • Risk of hyperkalaemia, citrate toxicity from transfusion
      • Calcium, magnesium, water infused to maintain usual hyponatraemia
    • Neohepatic phase
      • Vascular anastomoses
      • Immunosuppression with cyclosporin, azathioprine, prednisolone
      • Haemorrhage, coagulopathy still risks
      • Flushing cold hyperkalaemic fluid out of liver
      • Treat hypothermia, hyperkalaemia, acidosis
  • Emergence
    • ICU transfer, intubated
    • Risks of pneumonia, ARDS, anastomotic leaks, other infection

Anaesthesia with portal hypertension for shunt insertion


Major abdominal surgery in a high-risk patient

  • Preoperative
    • Assessment
      • Complications
        • Cardiac
          • Increased CO, decreased SVR, increased SvO2, BP and HR unchanged
          • Cardiomyopathy, arrhythmias
          • Decreased responsiveness to α-agonists
          • Decreased renal blood flow
        • Respiratory
          • Increased 2,3 DPG causing right shift of Hb-O2 dissociation curve
          • Vasodilators (VIP, glucagon, ferritin) cause pulmonary shunting,
          • Decreased pulmonary vascular response to hypoxia
          • Ascites may splint diaphragm (closing volume > FRC)
          • Decreased colloid oncotic pressure may predispose to pulmonary oedema
        • Haematological
          • Increased plasma volume, decreased Hb (bleeding, B12 deficiency), decreased albumen
          • Factor deficiencies: VII, V, X, fibrinogen
          • DIC may complicate surgery
        • Endocrine
          • Impaired glucose tolerance (increased glucagon, increased GH, insulin resistance)
          • Feminization of male patients
        • Other
          • Encephalopathy
          • Renal failure (hepatorenal syndrome, ATN)
          • Altered pharmacodynamics
          • Varices, haemorrhage
      • Decide whether further optimization is possible
        • Treatment of complications
          • Vitamin K or FFP, platelets if required
        • Specific therapy
          • Vasopressin: preportal vasoconstriction
            • Also coronary, arteriolar vasoconstriction
          • Somatostatin: decreased glucagon, gut activity, mesenteric blood flow
          • Propranolol: decreased CO, splanchnic vasoconstriction, decreased renin
            • Rebound bleeds with discontinuation
    • Investigation
      • FBE, U&E, LFT, clotting, XM, ABG
      • ECG, CXR if in failure
    • Premedication
      • Minimal if at risk of encephalopathy
      • Increased sensitivity to benzodiazepines
      • Antacid or H2-blocker for increased reflux risk
  • Intraoperative
    • Monitoring and access
      • Large bore IV access (consider multiple)
      • Routine monitoring, plus
      • CVC, arterial line, IDC, temperature
      • Blood and fluid warmer available
      • ABG, Hb and glucose measurement available
    • Anaesthetic technique
      • High mortality in patient in hepatic failure
      • Surgery is the major determinant of hepatic damage, not anaesthesia
      • General anaesthesia
        • Rapid sequence induction if recent bleeding or full stomach suspected
        • Avoidance of hepatotoxic drugs (e.g. halothane)
        • Some evidence of increased enzymes with ketamine, thiopentone and N2O
        • Decreased protein binding, so decreased dose of bound drugs such as thiopentone
        • Aim to maintain hepatic O2 delivery: BP, Hb, PaO2
      • Epidural analgesia
        • Contraindicated in coagulopathy or thrombocytopenia
        • Stress response reduces hepatic blood flow
        • Allows minimization of other anaesthetic drugs
    • Formation of shunt: flow from portal vein to IVC
      • Increased IVC flow
      • Decreased hepatic blood flow causes release of glucagon, VIP (vasodilators)
      • Decreased portal resistance, decreased SVR
      • Reflex increased SV, increased CO
  • Postoperative
    • HDU or ICU care may be needed
    • Epidural analgesia or judicious opioids
    • Careful fluid management

Kindly provided by Dr James Mitchell from his pharmacodynamics series


ArticleDate:20060821
SiteSection: Article
 
   
    
                                            
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