What are the anesthesia considerations for a 56-year-old male with hypertension (High Blood Pressure) and diabetes undergoing Laparoscopic Appendectomy under Spinal Anesthesia?

Anesthesia Considerations for Laparoscopic Appendectomy Under Spinal Anesthesia in a 56-Year-Old Male with Hypertension and Diabetes

Spinal anesthesia is a viable and safe option for laparoscopic appendectomy in this patient, with specific attention to hemodynamic management, glycemic control, and assessment for diabetic complications. 1, 2

Preoperative Assessment

Cardiovascular Evaluation

• Assess for cardiac autonomic neuropathy through orthostatic blood pressure measurements: measure BP after 10 minutes supine, then at 1,2, and 3 minutes after standing; orthostatic hypotension (≥20 mmHg systolic drop or ≥10 mmHg diastolic drop) indicates serious sympathetic dysautonomic damage and predicts increased hemodynamic instability with spinal anesthesia 3
• Patients with hypertension and diabetes undergoing spinal anesthesia are at significantly increased risk for hypotension due to sympathetic blockade causing peripheral vasodilation 4
• Do not initiate perioperative beta-blockers if the patient is not already on them, as this increases mortality and stroke risk in noncardiac surgery 3

Glycemic Management

• **Target HbA1c <8% for elective surgery**; postpone if HbA1c >8% or blood glucose >16.5 mmol/L (297 mg/dL) on the day of surgery 5
• Stop metformin the night before surgery due to lactic acidosis risk, particularly with renal impairment or hemodynamic instability 3, 5
• Discontinue SGLT2 inhibitors 3-4 days preoperatively to prevent euglycemic diabetic ketoacidosis 6, 5
• Hold other oral hypoglycemic agents on the morning of surgery 6
• If on insulin: give NPH at 50% usual dose or long-acting analogs at 75-80% usual dose 6

Diabetic Neuropathy Assessment

• Perform preoperative clinical examination for pre-existing polyneuropathy and document findings, as this is more critical in diabetic patients receiving neuraxial blocks 3
• Evaluate for difficult intubation using the palm print test (prayer sign) in long-term diabetics, as metabolic collagen disorders affect temporomandibular and atlanto-occipital joints, though conversion to general anesthesia is rare 3

Intraoperative Management

Spinal Anesthesia Technique

• Administer hyperbaric bupivacaine 0.5% (10-12 mg) at L2-L3 or L3-L4 with fentanyl 20-25 mcg intrathecally for adequate surgical anesthesia and improved postoperative analgesia 1, 7
• The 12 mg dose is generally adequate for lower abdominal procedures like appendectomy 4
• Consider combined spinal-epidural technique with epidural catheter at T10-T11 for inadequate spinal block or postoperative pain management 1, 8
• Maintain intra-abdominal pressure at 8-10 mmHg (lower than standard 12-15 mmHg) to minimize hemodynamic compromise and shoulder pain 2

Hemodynamic Monitoring and Management

• Monitor blood pressure every 3-5 minutes initially, then every 5-10 minutes after stabilization, as elderly hypertensive patients are at highest risk for hypotension 4
• Treat hypotension aggressively with titrated vasopressors (ephedrine or phenylephrine) rather than excessive fluid loading in diabetic patients who may have diastolic dysfunction 3, 4
• Hypotension requiring vasopressor support occurs in approximately 18% of patients undergoing laparoscopic surgery with spinal anesthesia 2
• Position patient in left lateral tilt or place blanket roll under right hip to prevent aortocaval compression 4

Glycemic Control During Surgery

• Target blood glucose 100-180 mg/dL (5.6-10.0 mmol/L) throughout the procedure 5
• Monitor capillary glucose every 2-4 hours while NPO, or hourly during prolonged procedures 6, 5
• Initiate 10% dextrose infusion if patient has been fasting and cannot maintain normoglycemia, stopping only if glucose exceeds 300 mg/dL 9
• Administer ultra-rapid insulin analog bolus subcutaneously if blood glucose >10 mmol/L (180 mg/dL) 6
• Do not target strict normoglycemia (<100 mg/dL), as this increases hypoglycemia risk without improving outcomes 5

Management of Intraoperative Complications

• Shoulder or neck pain (occurs in 12% of patients): treat with intravenous fentanyl 25-50 mcg or ketamine 10-20 mg 1, 2, 10
• Anxiety or discomfort: administer midazolam 1-2 mg or dexmedetomidine infusion (loading 0.5-1 mcg/kg over 10 minutes, then 0.2-0.7 mcg/kg/hr), though dexmedetomidine increases bradycardia risk (27% incidence) 1, 10
• Nausea: occurs in only 2% with spinal anesthesia versus 29% with general anesthesia; treat with ondansetron, avoiding dexamethasone >4 mg due to hyperglycemia risk 6, 2
• Conversion to general anesthesia is required in <1% of cases 2

Postoperative Management

Pain Control

• Injectable diclofenac or other NSAIDs are first-line for postoperative pain, required in approximately 36% of patients within 2 hours 2
• Standard analgesics (NSAIDs, acetaminophen, opioids) do not affect glycemic control and can be used without modification 6
• Effective pain control is critical as poorly controlled pain increases hyperglycemia risk 6
• Time to first analgesic requirement is significantly prolonged (13.6 hours) when intrathecal fentanyl is used versus bupivacaine alone (6.3 hours) 7

Glycemic Monitoring

• Continue blood glucose monitoring every 2-4 hours until patient is eating and stable 6, 5
• Resume oral feeding as soon as possible 6, 5
• Restart regular diabetes medications when blood glucose is 90-180 mg/dL (5-10 mmol/L) and patient is tolerating oral intake 6, 5
• Administer corrective subcutaneous insulin boluses if blood glucose exceeds 180 mg/dL postoperatively 6
• Consider hospitalization for IV insulin if blood glucose exceeds 300 mg/dL (16.5 mmol/L) 6

Monitoring for Complications

• Post-dural puncture headache occurs in 5.4% of patients; typically lasts 2-3 days and is managed conservatively 2
• Monitor for urinary retention, though incidence is similar to general anesthesia 7
• Average hospital stay is 2.3 days with 98.6% patient satisfaction 2

Critical Pitfalls to Avoid

• Never inject spinal anesthetic during uterine contractions (not applicable here, but critical safety principle) as CSF current may cause excessive cephalad spread 4
• Do not use bupivacaine 0.75% epidurally if conversion becomes necessary, as this concentration has been associated with cardiac arrest 4
• Avoid intravenous regional anesthesia (Bier block) with bupivacaine due to cardiac arrest risk 4
• Do not restart metformin before 48 hours post-major surgery and only after confirming adequate renal function 3
• Elderly patients (>65 years) exhibit greater spread, higher maximal level, and faster onset of spinal anesthesia, requiring careful dosing 4
• Patients with hepatic or renal impairment require reduced bupivacaine doses due to decreased clearance 4