Post Operative Fever

1. Post Operative Fever Tad Kim, M.D. UF Surgery tad.kim@surgery.ufl.edu (c) 682-3793; (p) 413-3222

2. Overview • Definition & Pathophysiology • Differential Diagnosis • The five “W” • Modified approach to DDx • Initial assessment and work-up • Management • Cases

3. Definition & Pathophysiology • Fever is temp ≥ 38 degrees Celsius • Manifestation of cytokine release/response • By monocyte, macrophages, endothelial cells • IL-1, IL-6, TNF-alpha, IFN-gamma • Act on the hypothalamic endothelium • Stimulate produx of PGE2 & cAMP release • cAMP acts as neurotransmitter & raises the “set-point” => heat conservation & production

4. Differential Diagnosis • The Five “W” & timing of each • Wind (POD#1) atelectasis, pneumonia • Water (POD#3) UTI, anastomotic leak • Wound (POD#5) wound infex, abscess • Walking (POD#7) DVT / PE • Wonder-drug or What did we do? • Many drugs cause fever, ?blood transfusions, central lines we put in (line sepsis)

5. Differential Diagnosis • Five W’s are a guide for the most common • But also learn to think worst-case scenario • “What can kill this patient if I miss the dx?” • In general, early fever is not infectious with one critical exception: Necrotizing fasciitis or soft tissue infection • Most early post-op fever resolves w/o tx • Simply a reaction/response to the surgery • Fever occuring later: more likely infectious

6. DDx – Modified Approach • Immediate fever – onset in OR or hrs after • Killers: • necrotizing infection (can kill rapidly) • Clostridium perfringens, Group A β-hemo strep • Tx: ABC, Resusc, Pen G, surgical debridement • malignant hyperthermia • Tx: ABC, Resusc, rapid cooling, IV dantrolene • Other: Allergic rxn (to abx) or transfusion • Look for hypotension, rash • Tx: Stop the offending agent

7. DDx – Modified Approach • Acute fever– within first week after surgery • In addition to five W’s, think of these: • Killers: • necrotizing infection (within 48hrs) • anastomotic leak (classically POD# 3 to 5) • new abd pain, distension, peritoneal signs • fever, tachycardia, hypotension • pulmonary embolism or MI (can p/w fever) • Other: VAP, aspiration, nosocomial infex, EtOH withdrawal (day 3), acute gout

8. DDx – Modified Approach • Subacute/delayed fever – after ~5days post-op, infectious etiology is more likely • #1: Wound infection (40%) • #2: UTI (29%) especially if indwelling Foley • #3: Pneumonia (12%) if on vent or COPD • Also think of: C.dif colitis, line sepsis & bacteremia, intra-abdominal abscess • Rarer: sinusitis, meningitis, peri-rectal abscess, acalculous cholecystitis, parotitis • Weeks out: endocarditis, infected prostheses

9. Initial Assessment • If called for fever, get to the bedside, get the nurse/flowsheet and ABC with vitals • Obtain a history or use the AMPLE format • Type of surgery, meds or blood given, other symptoms (rash, cough, dyspnea, chest pain, dysuria, leg swelling, painful IV site, abd pain) • Physical: • #1 check the wound or surgical site • #2 lung sounds, heart/abd/extremity exam • #3 check IV sites, central line, Foley, tubes

10. Work-Up • Labs if concerned about infection: • CBC w diff, Sputum Cx, UCx, Blood Cxx2 • Lumbar puncture (if AMS, neck pain, fever) • C.dif toxin assay • STAT gram stain if suspect necrotizing infex • Imaging: • CXR (for pneumonia) • Lower extremity venous duplex (for DVT) • CT scan (for abscess, leak; or PE protocol) • RUQ ultrasound (if suspect cholecystitis)

11. Management • Remove/replace sources of infection • Foley catheter, central lines, or peripheral IV’s • Open, debride, and drain infected wounds • Antibiotics not indicated for wound infex unless associated cellulitis • Tylenol 10mg/kg (ped) or 650mg po x1 • If suspect pneumonia, bacteremia, UTI, sepsis – start broad spectrum antibiotics

12. Case 1 • 58yo man 5hrs after bilateral total knee arthroplasty. Temp of 38.7 C • Only c/o knee pain controlled w meds • On no antibiotics, taking home meds • VS: Pulse 90, BP 130/70, O2 sat: 99% • Mild serosanguinous drainage from knees • No Foley or central lines, WBC 7 (normal) • What do you do?

13. Case 1 • What do you do? • A. Urine culture • B. Blood, urine cultures & CXR • C. Blood, urine cultures & vancomycin • D. Observation only

14. Case 2 • 65yo obese, diabetic female 5hrs s/p open chol’y for gangrenous cholecystitis. Called with T 40.0 C, tachycardia, abd pain • Sx: Altered mentation, abd pain • VS: P 140, BP 88/50, O2 Sat 94% • PE: Wound is blistered, +crepitus, sub-Q gas & dirty, dishwater drainage • Gram stain of fluid shows gram pos rods

15. Case 2 • What is the diagnosis? • A. Cellulitis • B. Diffuse peritonitis • C. Necrotizing fasciitis • D. Uncomplicated post operative fever • What is the organism on gram stain? • A. Group A strep • B. MRSA • C. Clostridium perfringens • D. Enterococcus

16. Case 2 Lessons • Necrotizing fasciitis • Type I: Polymicrobial with aerobes/anaerobes usu. occurs after surgery, in DM or PVOD • Type II: Monomicrobial 2ndary to Group A strep, Strep pyogenes • MRSA is becoming more common for Type II • ABC, ?intubate, 2 large IV, resuscitate • Early Pen G + Broad-spectrum antibiotics • Early surgical debridement • Mortality is 100% with antibiotics alone

17. Case 3 • 61yo F w rheumatoid arthritis on methotrexate undergoes left total hip. Has Foley catheter postoperatively. Fever of 38.1 C on POD#1, Foley is removed. Then has fever of 38.5 C on POD#4. • She has been ambulating, using incentive spirometry, O2 Sats and vitals are normal • Wound is clean

18. Case 3 • What is the most likely diagnosis? • A. Deep venous thrombosis • B. Urinary tract infection • C. Superficial wound infection • D. Prosthesis infection

19. Take Home Points • Know the five W’s as a rough guide for most common causes & timing • Learn to think of what can kill the patient • Also think: “what did we do to cause this?” • Targeted H&P / labs / imaging to rule out the killers, then confirm most likely cause • Should have a working diagnosis before labs • Know the dx & treatment of ‘nec fasciitis’