8.4 Hepatic, Renal & Gastrointestinal Pathophysiologies
Key Takeaways
- Hepatitis B carries the highest needlestick transmission risk of the major bloodborne viruses, hepatitis C has no vaccine and commonly leads to cirrhosis, and elective surgery is usually postponed during acute hepatitis.
- Cirrhosis causes portal hypertension with varices, coagulopathy, low albumin, a hyperdynamic low-resistance circulation, and encephalopathy, so teams prepare for bleeding with a rapid infuser, blood products, and viscoelastic testing.
- Renal failure brings hyperkalemia, acidosis, volume overload, anemia, uremic platelet dysfunction, and drug accumulation; cisatracurium avoids renal dependence, while morphine and meperidine metabolites accumulate.
- Arms with an arteriovenous fistula are protected from blood pressure cuffs, IV lines, and tight wraps, and hemodialysis patients are commonly dialyzed within about a day before elective surgery.
- Bowel obstruction, GERD, and hiatal hernia raise aspiration risk; congenital diaphragmatic hernia calls for gentle ventilation without prolonged bag-mask inflation, and nitrous oxide is avoided with bowel obstruction.
8.4 Hepatic, Renal & Gastrointestinal Pathophysiologies
The ASATT content outline lists hepatic, renal, and gastrointestinal diseases among the pathophysiologies candidates must recognize. Each one changes how drugs are handled, how the patient tolerates fluid shifts and blood loss, or how likely aspiration is, and each changes what the anesthesia technologist sets up before the case.
Hepatic Disease
Hepatitis
Hepatitis is inflammation of the liver. Common causes include viral infection (hepatitis A through E), alcohol, drugs and toxins (such as acetaminophen overdose), and autoimmune disease.
| Virus | Main Transmission | Occupational Relevance |
|---|---|---|
| Hepatitis A and E | Fecal-oral | Hand hygiene and food and water safety |
| Hepatitis B | Blood and body fluids | Highest needlestick transmission risk of the major bloodborne viruses; OSHA requires employers to offer vaccination to at-risk workers |
| Hepatitis C | Mainly blood | No vaccine; a leading cause of chronic hepatitis and cirrhosis |
| Hepatitis D | Blood; infects only people who have hepatitis B | Prevented by hepatitis B vaccination |
- Lab pattern: Liver cell injury raises AST and ALT. Bilirubin rises with more severe disease, and a rising INR signals lost synthetic function.
- Anesthesia implications: Elective surgery is usually postponed during acute hepatitis because perioperative risk is high. Standard Precautions apply to every patient, whether or not an infection is known.
Cirrhosis
Cirrhosis is irreversible scarring (fibrosis with regenerative nodules) after long-term liver injury. Its complications explain most anesthetic concerns:
| Complication | Mechanism | Perioperative Concern |
|---|---|---|
| Portal hypertension | Scar tissue blocks blood flow through the liver | Esophageal varices that can bleed with instrumentation; enlarged spleen |
| Coagulopathy and low platelets | Less clotting factor production; platelets trapped in the spleen | High INR, surgical bleeding, and need for blood products |
| Low albumin and ascites | Less albumin synthesis and fluid shifts | More unbound (active) drug; ascites raises aspiration risk and limits ventilation |
| Hyperdynamic circulation | Widespread vasodilation with low systemic vascular resistance | High cardiac output but a tendency toward hypotension |
| Hepatic encephalopathy | Ammonia and other toxins reach the brain | Increased sensitivity to sedatives |
| Hepatorenal and hepatopulmonary syndromes | Kidney failure or low oxygen levels caused by advanced liver disease | Low urine output; low oxygen saturation |
- Drug handling: Clearance of liver-metabolized drugs, such as midazolam and many opioids, slows. A larger volume of distribution can raise the initial dose needed for some neuromuscular blockers while prolonging their effect. Cisatracurium does not depend on the liver for elimination.
- Risk scores: The Child-Pugh score (bilirubin, albumin, INR, ascites, encephalopathy) and the MELD score (bilirubin, INR, and creatinine, with sodium added in MELD-Na) estimate surgical and transplant risk.
- Technologist setup: Prepare a rapid infuser and fluid warmer, confirm blood product availability, set up viscoelastic testing (TEG or ROTEM) and point-of-care labs, and prepare invasive pressure monitoring. Esophageal devices are placed only with provider direction when varices are known.
Renal Failure
Kidney failure can be acute kidney injury (AKI) or chronic kidney disease (CKD). AKI is grouped by cause:
- Prerenal: Reduced kidney perfusion from hypovolemia, hypotension, or heart failure
- Intrinsic: Damage to the kidney itself, such as acute tubular necrosis, nephrotoxins (contrast media, aminoglycosides), or glomerulonephritis
- Postrenal: Blocked urine flow from an enlarged prostate, stones, or an obstructed catheter
CKD means kidney damage, or a glomerular filtration rate (GFR) below 60 mL/min/1.73 m², lasting more than 3 months. End-stage kidney disease usually means a GFR below 15 or dependence on dialysis.
| Problem in Renal Failure | Perioperative Consequence |
|---|---|
| Hyperkalemia | Peaked T waves, dysrhythmias, and cardiac arrest; succinylcholine raises potassium further |
| Metabolic acidosis | Worsens hyperkalemia and hemodynamic instability |
| Volume overload and hypertension | Pulmonary edema risk; careful fluid limits |
| Anemia | Less erythropoietin production |
| Uremic platelet dysfunction | Bleeding despite a normal platelet count |
| Drug accumulation | Longer effects from kidney-cleared drugs and active metabolites |
- Drug choices: Cisatracurium (Hofmann elimination) avoids dependence on the kidneys. Active metabolites of morphine (morphine-6-glucuronide) and meperidine (normeperidine) accumulate. Sugammadex labeling does not recommend it in severe renal impairment, including patients on dialysis.
- Dialysis timing: Hemodialysis patients are commonly dialyzed within about a day before elective surgery, and potassium and volume status are rechecked afterward.
- Protect vascular access: Never place a blood pressure cuff, IV line, or tight wrap on an arm with an arteriovenous fistula or graft, and pad and position that arm carefully. Dialysis catheters are not used for routine infusions without provider direction.
- Technologist setup: Point-of-care potassium and blood gas testing, ECG monitoring, and supplies for treating hyperkalemia.
Gastrointestinal Disorders
| Disorder | Key Features | Anesthesia and Technologist Considerations |
|---|---|---|
| Congenital diaphragmatic hernia | Abdominal organs enter the chest through a diaphragm defect, most often the left posterolateral (Bochdalek) type, leaving the newborn with underdeveloped lungs and pulmonary hypertension | Avoid prolonged bag-mask ventilation, which inflates herniated bowel; intubate, ventilate gently at low pressures, decompress the stomach, and watch for pneumothorax; repair follows stabilization |
| Hiatal hernia | Part of the stomach slides through the esophageal hiatus; sliding hernias are far more common than paraesophageal hernias | Often occurs with reflux; fundoplication may use an esophageal bougie placed by the anesthesia provider in coordination with the surgeon; dissection near the hiatus can cause capnothorax |
| Gastroesophageal reflux disease (GERD) | A weak lower esophageal sphincter lets stomach acid reflux | Aspiration precautions follow the provider's plan; premedication may include an H2 blocker (cimetidine or famotidine), a proton pump inhibitor, non-particulate sodium citrate (Bicitra), or metoclopramide (Reglan) |
| Pancreatitis | Pancreatic inflammation, most often from gallstones or alcohol; serum lipase rises | Severe cases cause large fluid shifts, hypovolemia, low calcium, high glucose, ARDS, and kidney injury; prepare invasive monitoring, glucose and calcium testing, and fluid warmers |
| Bowel obstruction | Blockage from adhesions (the leading cause of small bowel obstruction), hernias, tumors, or volvulus | Full stomach with vomiting, distension, dehydration, and electrolyte losses; nasogastric decompression, two working suction setups for rapid sequence induction, and no nitrous oxide, which expands bowel gas |
Aspiration Risk Basics
Aspirating stomach contents causes chemical pneumonitis (Mendelson syndrome). Classic teaching links higher risk to gastric fluid with a pH below 2.5 and a volume above about 0.4 mL/kg (roughly 25 mL in adults). Emergency surgery, bowel obstruction, GERD, hiatal hernia, pregnancy, obesity, and diabetic gastroparesis all raise the risk. Before induction, the technologist confirms working suction, rapid sequence equipment, and a range of tube sizes.
A patient with end-stage kidney disease on hemodialysis has a left forearm arteriovenous fistula and is scheduled for right knee arthroscopy. What should the anesthesia technologist do when setting up monitoring and IV access?
A newborn with severe respiratory distress, a scaphoid (sunken) abdomen, and bowel sounds over the left chest is being stabilized. Which airway approach is most appropriate?
A patient with cirrhosis, ascites, esophageal varices, and an INR of 2.1 needs an emergency abdominal procedure. Which setup priority best matches this patient's pathophysiology?