ABS Surgical Critical Care cheat sheet

Oxygen delivery: DO2 = CO x CaO2 x 10; CaO2 = (1.34 x Hb x SaO2) + (0.0031 x PaO2).

Oxygen consumption: VO2 = CO x (CaO2 - CvO2) x 10; normal VO2 is ~110-160 mL/min/m2.

Shock is defined by inadequate DO2 relative to VO2; lactate rise and widened ScvO2-SvO2 gap signal dysoxia.

Mixed venous saturation (SvO2) <65% or ScvO2 <70% suggests inadequate cardiac output or anemia.

Acute respiratory distress syndrome (Berlin): PaO2/FiO2 <=300 with PEEP >=5, bilateral opacities, onset within 1 week, not cardiogenic.

Lung-protective ventilation: tidal volume 6 mL/kg predicted body weight, plateau pressure <=30 cmH2O.

Acute kidney injury (KDIGO): stage 1 = creatinine rise >=0.3 mg/dL or 1.5-1.9x baseline; stage 3 = >=3x or creatinine >=4.0 or RRT.

Continuous renal replacement therapy is preferred in hemodynamically unstable patients; intermittent HD for stable patients.

Sepsis-3: suspected infection plus SOFA increase >=2; septic shock = vasopressor need for MAP >=65 plus lactate >2 mmol/L despite fluids.

Cushing reflex: hypertension with widened pulse pressure and bradycardia indicates elevated intracranial pressure.

Beck triad of cardiac tamponade: hypotension, distended neck veins, muffled heart sounds.

Burn fluid resuscitation (Parkland): 4 mL x body weight (kg) x %TBSA; half in first 8 hours from injury time.

Rule of Nines: each arm 9%, each leg 18%, anterior trunk 18%, posterior trunk 18%, head 9%, perineum 1%.

Systemic inflammatory response syndrome criteria: temperature >38 or <36 C, HR >90, RR >20 or PaCO2 <32, WBC >12k or <4k or >10% bands.

Compensatory anti-inflammatory response follows SIRS; combined state is mixed antagonist response syndrome.

Trauma triad of death: hypothermia, acidosis, and coagulopathy; each worsens the others.

Hypermetabolic burn response: elevated resting energy expenditure up to 2x baseline, increased catecholamines and cortisol.

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

Revised Cardiac Risk Index predictors: ischemic heart disease, heart failure, cerebrovascular disease, insulin-dependent diabetes, creatinine >2.0, high-risk surgery.

Postoperative atrial fibrillation after noncardiac surgery: rate control first; anticoagulation decided by CHA2DS2-VASc and bleeding risk.

Venous thromboembolism prophylaxis: Caprini score guides modality; pharmacologic prophylaxis for moderate-high risk unless contraindicated.

Delirium risk factors: age >65, cognitive impairment, sensory deprivation, sleep disruption, immobility, pain, polypharmacy.

Anastomotic leak presents with tachycardia, fever, ileus, and rising lactate; CT with contrast is diagnostic.

Postoperative ileus vs. mechanical obstruction: ileus has diffuse air-fluid levels and no transition point; obstruction shows a transition zone.

Acute mesenteric ischemia: pain out of proportion to exam; lactate and metabolic acidosis are late findings; CT angiography is diagnostic.

Malignant hyperthermia: hypercarbia, rigidity, hyperthermia; treat with dantrolene 2.5 mg/kg IV and stop triggering agents.

Alcohol withdrawal: CIWA-Ar guides therapy; benzodiazepines are first-line; thiamine before glucose in malnourished patients.

Mechanical ventilation modes: volume-control delivers set tidal volume; pressure-control sets inspiratory pressure; both limit barotrauma if plateau <=30.

PEEP improves oxygenation by recruiting alveoli and reducing shunt; excessive PEEP causes barotrauma and hypotension.

Prone positioning for ARDS: 12-16 hours/day improves mortality when PaO2/FiO2 <150.

Vasopressors: norepinephrine first-line for septic shock; add vasopressin or epinephrine if MAP remains <65.

Fluid resuscitation: balanced crystalloids preferred over normal saline to reduce hyperchloremic acidosis.

Enteral nutrition: start within 24-48 hours in critically ill patients; trophic feeds acceptable if not tolerating full feeds.

Sedation: target RASS -2 to 0; daily interruption reduces ventilator days and ICU length of stay.

Glycemic control: target 140-180 mg/dL in critically ill patients; avoid hypoglycemia.

Stress ulcer prophylaxis: indicated with mechanical ventilation >48h or coagulopathy; PPI or H2 blocker.

Damage control surgery: abbreviated laparotomy, temporary closure, ICU resuscitation, then planned re-exploration.

Timing of surgery in septic shock: source control as soon as feasible; delay only for hemodynamic stabilization with ongoing vasopressors.

Perioperative risk: emergency surgery carries higher mortality than elective; ASA class and functional capacity refine risk.

ICU admission criteria: need for vasopressors, mechanical ventilation, invasive monitoring, or continuous renal replacement.

ICU staffing models: intensivist-led high-intensity staffing reduces mortality and length of stay versus low-intensity models.

Rapid response systems: early warning scores trigger evaluation; reduce cardiac arrests outside ICU.

Family-centered rounds and structured communication (e.g., SBAR) improve handoffs and reduce adverse events.

Quality metrics: ventilator-associated events, central line-associated bloodstream infections, catheter-associated UTIs, and delirium prevalence are tracked.

Triage and resource allocation: SOFA score and daily reassessment guide ICU bed allocation during surge.