Behind the Knife ABSITE 2026: Quick Hits for Trauma, Burn, Critical Care, and Pediatrics

Trauma, Burn, and Critical Care Quick Hits

• 🧠 GCS Score Calculation: A patient with eyes open to pain (2), inappropriate words (3), and withdrawal from pain (4) has a GCS of 9.
• ⚠️ TBI Management Goals: Maintain ICP < 20, ensure adequate oxygenation (PaO2 30-45), normal CO2, normal BP, and normothermia. Consider hypoventilation only if actively herniating.
• 🎯 Cerebral Perfusion Pressure (CPP): Target a CPP of 50-70.
• 💊 Anti-epileptic Medications: Typically given for seven days after severe traumatic brain injury.
• 🚫 Steroids: Not administered to head-injured patients.
• 📊 ARDS Diagnosis (Berlin Criteria): Bilateral opacities on CXR (non-cardiogenic), PaO2/FiO2 ratio < 300, and onset < 1 week. Graded by severity: mild (200-300), moderate (100-200), severe (<100).
• 🩹 Silver Sulfadiazine: Limited eschar penetration, not effective against Pseudomonas. Contraindicated in sulfa allergy or G6PD deficiency.
• ⚡ Silver Nitrate: Limited eschar penetration, ineffective against Pseudomonas, can cause electrolyte imbalances.
• 🔥 Mafenide Acetate: Better eschar penetration but painful; can cause metabolic acidosis.
• ⚖️ Fractional Excretion of Sodium (FeNa): Formula: (Urine Na * Plasma Cr) / (Plasma Na * Urine Cr). <1% indicates pre-renal AKI; >2% indicates intra-renal or post-renal AKI.
• 📈 Respiratory Quotient (RQ): Measures CO2 produced vs. O2 consumed. Fat (0.7), Protein (0.8), Carbs (1.0). RQ > 1 may indicate overfeeding; < 0.7 indicates starvation/ketosis.
• 🍎 Nutritional Requirements: Normal adult: 25-30 kcal/kg/day, 1g protein/kg/day. Hypermetabolic: 30-35 kcal/kg/day, 1.5-2g protein/kg/day. Burns: 35-40 kcal/kg/day, 2-2.5g protein/kg/day.
• 🔪 Rectal Injury: Diagnose with proctoscopy; treat with diversion.
• 🩸 Liver Injury with Persistent Bleeding: Suspect IVC or hepatic vein injury.
• 💥 Chance Fractures: Associated with duodenal or pancreatic injuries.
• 🦴 Open Book Pelvic Fracture: Apply a binder over the greater trochanters; consider angioembolization or pre-peritoneal pelvic packing.
• 🔵 Intraperitoneal Bladder Injury: CT shows contrast outlining small bowel; repair surgically (2 layers, absorbable suture).
• 🟠 Extraperitoneal Bladder Injury: Contrast extravasation into retroperitoneum; treat with Foley catheter for ~2 weeks.
• 🤰 Pregnant Trauma Patient: Estimate gestational age (uterus at umbilicus ~20 weeks), position left side down, fetal monitor if >24 weeks, pelvic exam for membranes, CT scan is indicated if clinically necessary.
• 🦵 Compartment Syndrome: Six Ps (Pain, Pallor, Poikilothermia, Pulselessness, Paresthesia, Paralysis). Diagnosis is clinical; perform fasciotomy promptly.
• 🚶 Penetrating Extremity Injury Workup: Obtain ABI/BBI (should be ~1).
• 🔪 Kidney Laceration: Generally spare the kidney; decompress with ureteral stents or drains. Can be left if viable.
• 췌 Pancreatic Head Injury: Drain the head, perform ERCP for ductal injury. Rarely, a Whipple may be needed.
• 💨 Pancreatic Tail Laceration (with duct involvement): Perform distal pancreatectomy, splectomy if possible.
• 🦠 Hollow Viscera Injury (Blunt): Suspect with bowel thickening, free fluid, high WBC; diagnostic laparotomy.
• 🕳️ Anterior Stomach Wall Penetrating Injury: Inspect the posterior wall as well.
• 🚀 Aortic Dissection: Initial treatment is impulse control (HR/BP within normal limits), start with esmolol.
• 🕸️ Blunt Aortic Injury with Pseudoaneurysm: Endovascular repair (EVAR) with vascular surgery.
• ❤️ Penetrating Cardiac Injury: Median sternotomy; intubate in the OR.
• ⚡ Neurogenic Shock vs. Spinal Shock: Neurogenic: hypotension, possibly bradycardia. Spinal: absence of reflexes (bulbocavernosus), temporary.
• 🩸 Trauma Resuscitation: Limit crystalloids, prefer whole blood or 1:1:1 product resuscitation (balanced resuscitation).
• 🚪 Damage Control Laparotomy Goals: Control bleeding, control contamination, get out quickly; leave temporarily closed.
• ⚠️ Indications for Damage Control Surgery: Lethal triad (acidosis, coagulopathy, hypothermia), urgent competing injuries, severe liver injuries needing packing, bowel ischemia, duodenal/pancreatic injuries.
• 🗺️ FAST Exam Limitations: Does not reliably detect fluid in the retroperitoneum (aortic, IVC, kidney injuries, pelvic fractures).
• 🌬️ Intubation in Trauma Bay: Resuscitate before intubation.
• 🎤 Cricothyroid Membrane: Anatomic landmark for emergency airway access (crike).

Pediatric Surgery Quick Hits

• 🍼 Maintenance IV Fluids (Pediatrics): 4-2-1 rule (4 cc/kg for first 10kg, 2 cc/kg for next 10kg, 1 cc/kg for >20kg). Use isotonic fluids with KCL and dextrose to prevent hyponatremia.
• 🫁 Pulmonary Sequestration vs. CPAM: Sequestration: no airway communication, systemic blood supply. CPAM: malformed lung communicating with airway. Both treated with lobectomy.
• 🧠 Most Common Mediastinal Mass (Children): Posterior: Neurogenic tumors (neuroblastoma, ganglioneuroma). Anterior: Lymphoma.
• 🟡 Choledochal Cyst: Most common is Type I (CBD dilation); treated with resection and hepaticojejunostomy.
• 💨 Congenital Diaphragmatic Hernia (CDH): 80% left-sided (Bochdalek). Stabilize before surgery (intubation, oscillator, ECMO, NG tube, fluids).
• 🌟 Most Common Solid Abdominal Malignancy (Children): Neuroblastoma (adrenals); may regress spontaneously, lower risk if <1 year old.
• নির্ণ Wilms Tumor (Nephroblastoma): Asymptomatic mass, metastasizes to bone/lung. Treat with nephrectomy +/- chemotherapy; do not spill tumor.
• 👶 Pyloric Stenosis: 3-5 week olds, projectile vomiting, hungry after vomiting. Palpable olive-like mass. Labs: hypochloremic, hypokalemic metabolic alkalosis. Diagnosis: Ultrasound (muscle thickness >3mm, length >14mm). Treatment: Pyloromyotomy.
• 🐍 Intussusception (Children): Often follows viral illness. Lead point: inflamed Peyer's patches. Can be lymphoma, Meckel's. Reduce with air contrast enema.
• 🥨 Duodenal Atresia: Double bubble sign on X-ray, bilious vomiting. Failure of recanalization. Associated with Down syndrome. Treatment: Duodenoduodenostomy.
• 🗣️ Tracheoesophageal Fistula (TEF): Most common is Type C (proximal atresia, distal fistula). Associated anomalies: VACTERL (Vertebral, Anorectal, Cardiac, TEF, Renal, Limb).
• 💩 Newborn Not Pooping: Consider Meconium Ileus (diagnose/treat with Gastrografin enema, check for CF) or Hirschsprung's disease.
• 🤢 Necrotizing Enterocolitis (NEC): Premature infants, bloody stools after formula. X-ray: pneumatosis intestinalis, portal venous gas. Treatment: NPO, antibiotics, resuscitation, surgery if perforation.
• 🫃 Gastroschisis vs. Omphalocele: Gastroschisis: right of umbilicus, no sac, low associated abnormalities. Omphalocele: from umbilicus, has sac, higher risk of abnormalities (cardiac).

Biostatistics Quick Hits

• 📊 Cohort Study: Observational, exposure vs. non-exposed (prospective/retrospective). Calculates Risk Ratio.
• 🧐 Case-Control Study: Observational, selected by outcome (cases vs. controls). Retrospective. Calculates Odds Ratio. Good for rare diseases.
• ❌ Type I Error (Alpha): Rejecting the null hypothesis incorrectly. Associated with p-value.
• ✅ Type II Error (Beta): Accepting the null hypothesis incorrectly. Decreased by increasing power.
• 📉 P < 0.05: Less than 5% likelihood that the difference is due to chance alone.
• ⚖️ Student's t-test: Compares means between two independent groups (continuous data).
• 📈 ANOVA: Compares means between >2 independent groups (continuous data).
• 👯 Paired t-test: Compares means between two related groups (e.g., pre-op vs. post-op in the same patients).
• 📊 Chi-squared Test: Compares two groups with categorical variables (e.g., hair color, diagnosis).
• 🔍 Sensitivity: Likelihood of being positive in disease (True Positive / (True Positive + False Negative)). SnNout (Sensitivity rules OUT).
• 🧐 Specificity: Likelihood of being negative in disease (True Negative / (True Negative + False Positive)). SpPIn (Specificity rules IN).
• ❓ Positive Predictive Value (PPV): Probability of having disease given a positive test (True Positive / (True Positive + False Positive)). Depends on prevalence.
• ❌ Negative Predictive Value (NPV): Probability of not having disease given a negative test (True Negative / (True Negative + False Negative)). Depends on prevalence.