Patient: 24 y/o F with T1DM, ran out of insulin 3 days ago, presents with nausea, vomiting, abdominal pain, and Kussmaul breathing.

Key findings: HR 118, BP 98/62, RR 28. BG 480, pH 7.12, bicarb 6, AG 28, K⁺ 5.4, BHB 6.8 mmol/L.

Management:

• NS 1L bolus over 1h, then 0.45% NS at 250 mL/hr
• K⁺ 5.4 (>3.5), start regular insulin drip at 0.14 units/kg/hr (no bolus), OR alternatively 0.1 u/kg IV bolus + 0.1 u/kg/hr drip ADA, 2026
• Add KCl 20 mEq/L to each liter of IVF (total body K⁺ depleted despite normal serum K⁺)
• When BG < 250, add D5 to IVF and reduce insulin to 0.05 units/kg/hr

Teaching point: Serum K⁺ is artificially elevated due to acidosis-driven transcellular shift. Total body K⁺ is always depleted in DKA. Aggressively replete as insulin drives K⁺ intracellularly.

Patient: 58 y/o M with T2DM on empagliflozin and metformin, presents with 2 days of nausea, vomiting, and fatigue after a GI illness.

Key findings: BG 185, pH 7.22, bicarb 12, AG 22, BHB 5.2 mmol/L. K⁺ 4.1.

Management:

• Recognize euglycemic DKA, glucose near-normal but AG acidosis with ketones
• Hold SGLT2 inhibitor immediately
• Start insulin drip + D10 infusion (glucose already low, needs dextrose from the start)
• Volume resuscitate aggressively, SGLT2i causes osmotic diuresis

Teaching point: SGLT2 inhibitors mask hyperglycemia by enhancing renal glucose excretion. Always check ketones in SGLT2i users presenting with nausea/vomiting, even if glucose is normal.

Patient: 31 y/o F with T1DM, presenting with DKA triggered by UTI. Found altered in the ED.

Key findings: BG 520, pH 7.08, bicarb 5, AG 30, K⁺ 2.9, ECG shows U waves and prolonged QTc.

Management:

• DO NOT start insulin, K⁺ < 3.5 is an absolute contraindication
• Aggressive K⁺ repletion: KCl 40 mEq/hr IV via central line with continuous telemetry
• Start insulin ONLY when K⁺ ≥ 3.5 (recheck q1h during repletion)
• Treat UTI precipitant with appropriate antibiotics

Teaching point: Insulin before K⁺ repletion in hypokalemic DKA causes fatal arrhythmias. This is the single most important safety rule in DKA management.

Patient: 78 y/o F with DM2 and CKD3, presents with confusion, dysuria, and fever 39.2°C for 1 day.

Key findings: HR 112, BP 108/68, RR 24. Lactate 4.2, WBC 18.4K, Cr 2.8 (baseline 1.6), UA positive for nitrites and leukocyte esterase.

Management:

• Blood cultures x2 drawn, then ceftriaxone 1g IV within 1 hour SSC, 2026
• 30 mL/kg LR bolus (lactate ≥ 4 = mandatory resuscitation)
• Repeat lactate at 2h, clearance ≥ 10% is the target
• CT abdomen to rule out renal abscess or obstruction

Teaching point: Cryptic shock, lactate ≥ 4 with normal blood pressure. This patient meets septic shock criteria even though MAP is adequate. Do not be falsely reassured by a normal BP when lactate is elevated.

Patient: 62 y/o M with COPD, presents with productive cough and fevers. CXR shows RLL consolidation. MAP 52 after 2L LR.

Key findings: HR 128, RR 32, SpO₂ 88% on 6L NC. Lactate 6.8, WBC 22K, procalcitonin 14.5.

Management:

• Norepinephrine via peripheral IV, do not delay for central line CENSER, 2019
• Cefepime 2g IV q8h + vancomycin 25 mg/kg load (pneumonia is not an anaerobic source, SSC 2026 / Chanderraj, 2024 prefers cefepime over Zosyn)
• NE at 0.3, MAP still 58, add vasopressin 0.03 u/min VASST, 2008
• Hydrocortisone 50 mg IV q6h (ongoing vasopressor-dependent shock) ADRENAL, 2018

Antibiotic Stewardship: Day 2, sputum culture grows S. pneumoniae (pan-sensitive). MRSA nasal swab negative (NPV > 95%). De-escalate: stop vancomycin, narrow cefepime → ceftriaxone 1g IV daily. Check PCT trend, if ≥ 80% decline from peak, target 5-day total course.

Teaching point: Vasopressor escalation: NE first → vasopressin second (fixed 0.03 u/min) → hydrocortisone if still requiring high-dose pressors. Wean NE first, vasopressin last. Always reassess antibiotics at 48-72h when cultures finalize.

Patient: 55 y/o F, admitted with severe CAP and sepsis. Started on cefepime + vancomycin empirically (SSC 2026, pneumonia is not an anaerobic source).

Key findings: Admission PCT 8.2. Blood cultures grow pan-sensitive S. pneumoniae. MRSA nasal swab negative. Day 3: PCT 1.4 (83% decline), afebrile x24h.

Management:

• De-escalate vancomycin (MRSA swab negative, NPV > 95%)
• Narrow cefepime to ceftriaxone (culture-directed for S. pneumoniae)
• PCT ≥ 80% decline, stop antibiotics at day 5 PRORATA, 2010
• Total duration: 5 days (not the traditional 7-14)

Antibiotic Stewardship: Culture-directed narrowing is the goal. MRSA swab negative → stop vancomycin. Pan-sensitive organism → narrow to simplest effective agent. PCT-guided stop rule avoids unnecessary antibiotic days, fewer C. diff, less resistance, shorter stay.

Teaching point: Procalcitonin-guided de-escalation safely reduces antibiotic duration by 2-3 days. Stop rule: PCT < 0.25 or ≥ 80% decline from peak. Every unnecessary antibiotic day increases C. diff and resistance risk.

Patient: 78F from nursing home, altered mental status, T 39.2°C, HR 112, BP 82/48, WBC 22k. Foley catheter in place. UA: positive nitrites, leukocyte esterase, bacteria.

Key findings: Lactate 4.8 mmol/L → septic shock.

Management:

• Blood cultures × 2 + urine culture BEFORE antibiotics
• Cefepime 2g IV within 1 hour (covers Pseudomonas, catheter-associated UTI risk). Add vancomycin if concerned for MRSA bacteremia.
• 30 mL/kg LR bolus. Reassess after each liter.
• Norepinephrine via peripheral IV, don't wait for central line SSC, 2026

Antibiotic Stewardship: Day 2, urine culture grows E. coli (pan-sensitive). Narrow cefepime → ceftriaxone 1g IV daily. Plan transition to PO ciprofloxacin or TMP-SMX for discharge. Total course: 7-10 days for complicated UTI.

Teaching point: Catheter-associated UTI + septic shock = remove the catheter (source control), cover Pseudomonas empirically, start pressors early, and narrow at 48h when cultures return.

Patient: 55M with diabetes, rapidly spreading erythema on left leg × 12 hours. Pain out of proportion to exam. Crepitus on palpation. T 39.8°C, HR 125, BP 95/58, WBC 28k, lactate 5.2.

This is a surgical emergency, NOT a medical one.

• Do NOT wait for LRINEC score if clinical suspicion is high. Pain out of proportion + crepitus + sepsis = OR now.
• Vancomycin + pip-tazo + clindamycin (clindamycin inhibits toxin production in Group A Strep)
• Emergent surgical consult → radical debridement within hours. Every hour of delay ≈ +7.6% mortality.
• Expect return to OR every 24–48h for re-exploration until margins are clean.

Antibiotic Stewardship: Post-debridement, wound cultures guide narrowing. If Group A Strep confirmed → narrow to penicillin G + clindamycin (toxin suppression). If polymicrobial → maintain broad coverage. Duration guided by clinical response, not a fixed number of days.

Teaching point: Nec fasc is a surgical disease with medical support. The antibiotic that matters most is the scalpel. Call surgery BEFORE imaging.