Necrotizing Fasciitis Case File

Necrotizing Fasciitis Case File

Eugene C. Toy, MD, Patti Jayne Ross, MD, Benton Baker III, MD, John C. Jennings, MD

CASE 24

A 28-year-old woman who underwent a cesarean delivery 1 week ago is brought into the emergency room with a blood pressure of 60/40 mm Hg. The patient’s husband states that she had 2 days of nausea and vomiting, fever up to 102°F (38.8°C), and myalgias. The reason for the cesarean was arrest of active phase, with cervical dilation at 5 cm for 3 hours despite strong uterine contractions. She was discharged home on postoperative day 3 in good condition. On examination, the patient appears lethargic and has mental confusion. Auscultation of her heart reveals tachycardia. The lung examination demonstrates slight crackles at the lung bases. The abdomen is tender throughout, and the fundus of the uterus is slightly tender. The skin incision is tender, red, and indurated. Upon opening the incision, purulent material is expressed. The underlying tissue is palpated and has a brawny texture with crepitance noted. The laboratory evaluation reveals a hemoglobin level of 15 g/dL and a serum creatinine of 2.1 mg/dL.

» What is the most likely diagnosis?

» What is the next step in therapy?

ANSWER TO CASE 24:

Necrotizing Fasciitis                                               

Summary: A 28-year-old woman who underwent an uncomplicated cesarean 1 week ago has fever up to 102°F (38.8°C), myalgias, vomiting, hypotension, confusion, and a skin incision that is infected with underlying tissue revealing a brawny texture and crepitance. She has evidence of hemoconcentration and renal insufficiency.

• Most likely diagnosis: Necrotizing fasciitis.
• Next step in therapy: Isotonic intravenous (IV) fluids, broad-spectrum antibiotics, and immediate surgical debridement.

ANALYSIS

Objectives

1. Recognize the manifestations of shock.

2. Understand that necrotizing fasciitis is a rare but potentially fatal infection that can affect patients.

3. Understand that aggressive fluid resuscitation, broad-spectrum antibiotics, and immediate surgical debridement are fundamental in the treatment of necrotizing fasciitis.

Considerations

This patient presents with multiple life-threatening issues. First, the hypotension must be recognized, since her blood pressure is 60/ 40 mm Hg. Her mean arterial pressure is 47 mm Hg, which is insufficient to maintain cerebral perfusion. Regardless of the etiology, the blood pressure needs to be supported immediately. Because the patient has a fever of 102°F (38.8°C) with hypotension and no history of hemorrhage or postpartum bleeding, septic shock is the most likely diagnosis. The first step in resuscitation should be to support the blood pressure when low, with aggressive use of intravenous isotonic fluids. A Foley catheter can help to assess urine output and indirectly kidney perfusion, particularly since the patient has an elevated serum creatinine level. The goal is to keep the mean arterial blood pressure at least 65 mm Hg to perfuse her vital organs. Ideally, this patient would have a urine output of at least 25 to 30 mL/ h (depending on the degree of renal insufficiency). Furthermore, this woman most likely has necrotizing fasciitis since the underlying infected tissue has an abnormal consistency upon palpation. The crepitance is due to gas in the soft tissue, most likely due to anaerobic bacteria. Her myalgias, fever, nausea, and vomiting indicate the systemic nature of the infection.

APPROACH TO:

Necrotizing Fasciitis                                           

DEFINITIONS

NECROTIZING FASCIITIS: A serious infection of the muscle and fascia usually caused by multiple organisms or anaerobes. It can involve surgical infections, traumatic injury, or rarely Group A Streptococci (flesh-eating bacteria).

GROUP A STREPTOCOCCAL TOXIC SHOCK SYNDROME: Rapidly progressing infection of the episiotomy or cesarean delivery incision (“flesh-eating bacteria” syndrome).

SHOCK: Condition of circulatory insufficiency where tissue perfusion needs are not met.

SEPTIC SHOCK: Circulatory insufficiency due to infection or the body’s response to infection, commonly caused by gram-negative endotoxins.

Mean arterial pressure (MAP) = [(2 × Diastolic blood pressure)

                                                     + (1 × Systolic blood pressure)]/ 3

CLINICAL APPROACH

The management of septic shock includes copious intravenous fluids with close monitoring of urine output and blood pressure. At times, invasive hemodynamic monitoring with a central venous catheter or Swan–Ganz line is needed. Intravenous antibiotics should be broad spectrum to include penicillin, gentamicin, and metronidazole or other anaerobic agent, and dopamine or dobutamine is sometimes required when fluids alone are insufficient to maintain the blood pressure. Addressing the underlying etiology of the septic shock is important. When dealing with an aggressive wound infection, immediate surgical debridement, sometimes very radical or wide excisional procedures, is warranted. Necrotic and infected tissue must be removed, and sometimes, it requires multiple surgeries. Methicillinresistant Staphylococcus aureus sometimes complicates wound infections; this is associated with a worse prognosis.

Monitoring of blood pressure, heart rate, oxygen saturation, urine output, and neurological status is important. Once the patient is stabilized, treating the underlying cause typically leads to resolution. Septic shock initially presents as decreased urine output and if untreated, proceeds to ischemia of vital organs and death.

COMPREHENSION QUESTIONS

24.1 A 35-year-old woman is noted to have a blood pressure of 80/ 40 mm Hg, fever, and abdominal pain. Which of the following is the likely mechanism of the patient’s hypotension?

A. Cardiac contractility dysfunction

B. Cardiac bradycardia

C. Third spacing of fluid

D. Vasodilation

24.2 A 45-year-old woman is noted to have a surgical incision site that is suspicious for necrotizing fasciitis. Which of the following is most consistent with necrotizing fasciitis?

A. Redness of the surgical incision

B. Induration and edema of the surgical incision

C. Gas in the surgical tissue

D. Gram-negative rods growing from blood culture

24.3 A 30-year-old woman is brought into the emergency department with fever and a blood pressure of 70/ 40 mm Hg. She is presumed to be in septic shock. Which of the following is a fundamental principle for the treatment?

A. Intravenous normal saline

B. Plasmapheresis

C. Oral fluid resuscitation

D. Await blood culture results prior to initiation of antibiotic therapy

ANSWERS

24.1 D. The pathophysiology of septic shock is vasodilation usually due to endotoxins, although at times, such as with S. aureus (toxic shock syndrome), exotoxins can be causative. The vasodilation leads to hypotension, and is treated with IV fluids. If the IV fluids are insufficient to produce a correction in hypotension, then vasoconstrictors are indicated, such as dopamine. Late in the course of septic shock, cardiac dysfunction can occur; however, at this stage, the patient is typically in a near terminal condition.

24.2 C. Gas in the muscle or fascia is indicative of necrotizing fasciitis, likely due to a clostridial species. Induration and redness of the surgical wound are suggestive of a superficial wound infection, in which the skin and subcutaneous tissue are infected. This is a superficial surgical site infection, and needs to be opened. The superficial wound infection is not as lifethreatening as when a deep surgical site infection occurs.

24.3 A. Intravenous isotonic fluids are the initial treatment of choice for septic shock. The cornerstones of therapy include removing the nidus of infection, antibiotic therapy, and support of the blood pressure. Plasmapheresis is not a major part of the treatment of septic shock.

    CLINICAL PEARLS    

» The cornerstones of treatment of septic shock include aggressive intravenous fluids, source control, antibiotic therapy, and monitoring perfusion and organ function. » Source control in septic shock means removing the etiology of the infection. » The sunburn-like rash and/or desquamation are typical for S. aureus infections. » The initial antibiotic therapy for serious S. aureus infections is generally intravenous nafcillin or methicillin unless methicillin resistance is suspected, in which case vancomycin is used. » Hypotension that persists despite intravenous isotonic fluid replacement generally requires pressor support such as with intravenous infusion of dopamine.

REFERENCES

Cunningham FG, Leveno KJ, Bloom SL, Hauth JC, Gilstrap LC III, Wenstrom KD. Puerperal infection. In: Williams Obstetrics. 24th ed. New York, NY: McGraw-Hill; 2014:671-688. Gambone JC. Gynecologic procedures. In: H acker NF, 

Gambone JC, H obel CJ, eds. Essentials of Obstetrics and Gynecology. 5th ed. Philadelphia, PA: Saunders; 2009:332-344. Katz VL. Postoperative counseling and management. In: 

Katz VL, Lentz GM, Lobo RA, Gersenson DM, eds. Comprehensive Gynecology. 6th ed. St. Louis, MO: Mosby-Year Book; 2012:661-710.

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