AOBS Surgery cheat sheet

Coronary steal after internal mammary artery grafting is treated by reimplanting the IMA or reducing the native coronary stenosis; ligating the IMA alone is not a solution.

Postoperative atrial fibrillation after CABG is treated first with beta-blockade and electrolyte correction; amiodarone is added for refractory or hemodynamically significant cases.

Lung cancer T staging: tumor >7 cm is T4; satellite nodule in the same lobe is T3; ipsilateral different lobe is T4; contralateral lobe is M1a.

Aortic dissection with malperfusion or rupture requires emergent operative repair; type B without complications is managed with anti-impulse therapy.

Cardiac tamponade physiology: equalization of diastolic pressures, pulsus paradoxus, and right atrial collapse; pericardiocentesis is temporizing.

Esophageal perforation is treated with broad-spectrum antibiotics and source control; primary repair within 24 hours, drainage and diversion beyond.

Chest tube output >200 mL/hr for 2-3 hours or >1500 mL total suggests re-exploration for bleeding after cardiac surgery.

Acute appendicitis: Alvarado score components are migratory pain, anorexia, nausea/vomiting, right lower quadrant tenderness, rebound, fever, and leukocytosis.

Small bowel obstruction with strangulation signs (fever, tachycardia, peritoneal signs, elevated lactate) mandates emergent laparotomy rather than observation.

Hernia repair: mesh preferred for clean elective inguinal hernia; contaminated fields favor tissue repair or biologic mesh.

Pancreatic pseudocyst requires maturation of at least 4 weeks before internal drainage; symptomatic or enlarging cysts are drained earlier.

Thyroidectomy: recurrent laryngeal nerve injury causes hoarseness; bilateral injury causes stridor and airway obstruction; hypocalcemia follows parathyroid devascularization.

Colorectal cancer: right-sided lesions present with anemia and mass; left-sided with obstruction and change in bowel habits.

Damage control laparotomy: temporary abdominal closure with negative-pressure dressing; planned re-exploration every 24-48 hours.

Sepsis-3 defines sepsis as suspected infection plus SOFA increase of 2 or more; septic shock requires vasopressors to maintain MAP 65 mmHg plus lactate >2 mmol/L despite fluid resuscitation.

Acute respiratory distress syndrome (Berlin): onset within 1 week, bilateral opacities, not cardiac failure; PaO2/FiO2 mild 200-300, moderate 100-200, severe <100.

Ventilator-associated pneumonia: new infiltrate plus fever, leukocytosis, and purulent secretions after 48 hours of intubation; culture-directed therapy.

Abdominal compartment syndrome: intra-abdominal pressure >20 mmHg with new organ dysfunction; decompressive laparotomy is definitive.

Transfusion in critically ill: restrictive strategy (hemoglobin <7 g/dL) is preferred except in active ischemia or hemorrhage.

Propofol infusion syndrome: metabolic acidosis, rhabdomyolysis, renal failure, and arrhythmia with high-dose prolonged infusion; discontinue immediately.

Acute kidney injury KDIGO staging: stage 1 creatinine rise 0.3 mg/dL or 1.5-1.9x baseline; stage 2 2.0-2.9x; stage 3 3x or dialysis.

Ruptured abdominal aortic aneurysm: permissive hypotension (systolic 70-90 mmHg) until hemorrhage control; avoid aggressive fluid resuscitation.

Carotid endarterectomy is indicated for symptomatic stenosis 70-99% and selected asymptomatic stenosis >60-70% with acceptable perioperative risk.

Peripheral arterial disease: ABPI <0.9 suggests disease; >1.3 suggests non-compressible vessels (calcification, diabetes).

Acute limb ischemia (Rutherford): pulseless, paresthesia, pallor, pain, paralysis, poikilothermia; paralysis and paresthesia signal threatened limb requiring emergent revascularization.

Aortic dissection type A involves the ascending aorta and requires emergent surgery; type B is managed medically unless complicated.

Deep vein thrombosis: proximal (popliteal or above) warrants anticoagulation; isolated calf DVT may be managed with serial ultrasound.

Compartment syndrome after revascularization: pain out of proportion, tense compartment, paresthesia; fasciotomy is definitive and emergent.

Eligibility: BMI ≥40, or BMI ≥35 with obesity-related comorbidity; some guidelines accept BMI ≥30 with type 2 diabetes.

Roux-en-Y gastric bypass causes dumping syndrome from rapid emptying of hyperosmolar contents; sleeve gastrectomy causes reflux and staple-line leak.

Post-bypass micronutrient deficiency: iron, vitamin B12, folate, calcium, and vitamin D are common; thiamine deficiency causes Wernicke encephalopathy.

Marginal ulcer after gastric bypass: occurs at gastrojejunostomy; associated with NSAIDs, smoking, and Helicobacter pylori.

Sleeve gastrectomy leak typically presents at the proximal staple line near the angle of His with tachycardia and left shoulder pain.

Internal hernia after gastric bypass: intermittent abdominal pain with nausea and normal imaging may still require diagnostic laparoscopy.

Anastomotic stricture after gastric bypass presents with dysphagia and vomiting; treated with endoscopic dilation.

Traumatic brain injury: GCS ≤8 requires intubation; avoid hypotension (systolic <90-100 mmHg) and hypoxia (SpO2 <90%) to prevent secondary injury.

Elevated intracranial pressure: head of bed 30 degrees, normocapnia (PaCO2 35-40), hypertonic saline or mannitol; hyperventilation only as a bridge for herniation.

Subdural hematoma: crescent-shaped, crosses sutures; epidural hematoma: lens-shaped, does not cross sutures, associated with middle meningeal artery injury.

Aneurysmal subarachnoid hemorrhage: nimodipine for vasospasm prophylaxis; clip or coil within 72 hours; monitor for hydrocephalus and rebleeding.

Brain death criteria: unresponsive coma, absent brainstem reflexes, apnea with PaCO2 rise; confounders must be excluded.

Glioblastoma: maximal safe resection followed by temozolomide and radiation; IDH status and MGMT promoter methylation guide prognosis.

Lumbar disc herniation with cauda equina syndrome (saddle anesthesia, urinary retention) requires emergent decompression.

Status epilepticus: first-line benzodiazepines; second-line levetiracetam, valproate, or fosphenytoin; refractory requires continuous infusion and EEG monitoring.

Subarachnoid hemorrhage vasospasm peaks days 3-14; monitor with transcranial Doppler and treat with nimodipine and euvolemia.

Intracerebral hemorrhage: blood pressure control (systolic ~140 mmHg) reduces hematoma expansion; reverse anticoagulation immediately.

Hyperosmolar therapy targets serum sodium 145-155 mmol/L or osmolality 300-320 mOsm/kg for cerebral edema.

Targeted temperature management after cardiac arrest: 32-36 °C for at least 24 hours; avoid fever afterward.

Neurogenic stunned myocardium after SAH: troponin elevation, reversible wall motion abnormality, and pulmonary edema; supportive care.

Continuous EEG is indicated for unexplained coma after cardiac arrest or with burst suppression; nonconvulsive seizures are common.

Skin graft: split-thickness requires vascularized bed; full-thickness provides better contour and less contracture; both require adequate perfusion.

Free flap monitoring: color, capillary refill, temperature, and Doppler signal; venous congestion appears dark and brisk, arterial insufficiency pale and slow.

Burn resuscitation: Parkland formula 4 mL/kg/%TBSA lactated Ringer's in 24 hours, half in first 8 hours from injury time.

Pressure ulcer staging: stage I intact skin with nonblanchable erythema; stage II partial-thickness; stage III full-thickness to fascia; stage IV to bone or muscle.

Cleft lip repair timing: rule of 10s (weight 10 lb, hemoglobin 10 g/dL, age 10 weeks); palate repair around 9-12 months.

Basal cell carcinoma: locally invasive, rarely metastasizes; margins of 4-5 mm for low-risk lesions; Mohs for high-risk sites.

Tissue expansion requires adequate overlying skin and a stable bed; complications include exposure, infection, and deflation.

Testicular torsion: sudden severe pain with high-riding testis and absent cremasteric reflex; detorsion and orchiopexy within 6 hours preserves viability.

Renal colic: noncontrast CT is first-line; stones <5 mm often pass spontaneously; >10 mm rarely pass and may require intervention.

Prostate cancer screening: PSA with shared decision-making; elevated PSA prompts risk stratification, not immediate biopsy in all cases.

Benign prostatic hyperplasia: alpha-blockers relax smooth muscle; 5-alpha reductase inhibitors shrink gland over months and lower PSA by about half.

Fournier gangrene: necrotizing fasciitis of perineum; emergent debridement and broad-spectrum antibiotics.

Bladder cancer: painless gross hematuria is the classic presentation; cystoscopy is diagnostic; non-muscle-invasive disease treated with transurethral resection and intravesical therapy.

Ureteral injury during pelvic surgery: suspect with oliguria, elevated creatinine in drain fluid, or hydronephrosis; repair with stenting or reimplantation.