A 43-years-old Caucasian male (height 198 cm, weight 115 kg, tobacco smoker – 1 packet of cigarettes/day) was admitted to the intensive care unit (ICU) of a university hospital from a municipal hospital because of multiorgan dysfunction syndrome associated with infection and necrosis of the skin, subcutaneous tissue, and fascia of the left lower leg. The signs and symptoms of the disease – edema and pain affecting the left leg-began 7 days before admission. The patient's medical history was significant for hepatitis C (HCV), treated with ribavarin and interferon, and diabetes mellitus treated with insulin. On the day of admission the HCV-RNA test was negative. A mosquito bite was the probable triggering event.
On admission to the ICU the patient was confused, with a Glasgow Coma Scale (GCS) of 9. He was afebrile, had tachycardia, with a heart rate of 120 beats per minute, hypotension, with a blood pressure of 90/50 mmHg, and relative respiratory insufficiency (oxygen saturation of 88% – 90%). He had moderately-dilated pupils with a delayed light reflex. We noted crepitus over the bilateral lung fields, a tender abdomen with absent bowel sounds, and oliguria. There were numerous hemorrhagic extravasations on the skin. Examination of the left leg revealed diffuse edema of the skin, with marked erythema and necrosis; margins of infection were sharply demarcated, spreading onto the buttock and perineum on the left side (Figure ). Laboratory tests showed a metabolic acidosis, with the following values: base excess -15 mmol/l, lactate level 7.3 mmol/l, PaO2 64 mmHg, platelet count 29,000/mm3, International Normalized Ratio (INR) 2.24, serum creatinine 691.6 μmol/l, bilirubin 62.6 μmol/l, and C-reactive Protein (CRP) 224.6 μg/dl.
The Acute Physiology and Chronic Health Evaluation (APACHE) II score on the day of admission was 31 points and the Sequential Organ Failure Assessment (SOFA) score was 18 points. The patient required fluid resuscitation, endotracheal intubation, mechanical ventilation in BiPAP (bilevel positive airway pressure) mode, continuous intravenous infusion of catecholamines (epinephrine, norepinephrine) and low doses of steroids to restore blood pressure. After obtaining cultures from the affected tissue, blood and bronchoalveolar lavage (BAL) in appropriate media, empirical, broad-spectrum antibiotics were immediately administered (meropenem 3 g/day in a 3-h infusion, vancomycin 3 g/day in continuous infusion, metronidazole 1.5/day in 3 divided doses). Because of progressive organ dysfunction, therapy was started with activated protein C, in doses of 24 μg/kg/h; continuous veno-venous hemofiltration (CVVH) was also started. After several hours, the patient developed atrial fibrillation with a ventricular rate of 140 beats per minute and his blood pressure decreased to 80/50 mmHg. Electrical cardioversion was performed three times, followed by continuous infusion of cordarone (12 mg/kg/day). During this time, intensive fluid resuscitation was administered. During the first day, the patient received 12,800 ml of fluid (colloids and crystalloids). His unstable condition did not allow for early surgical management.
The cultures from the affected areas of skin contained Streptococcus pyogenes and Staphylococcus sciuri. Based on sensitivity results, vancomycin and metronidazole were discontinued, and penicillin G was started at a dose of 60 million units a day (intravenous) in 6 divided doses. Because the patient's poor condition persisted and the microbes were sensitive to clindamycin, it was added at 2.7 g/day in 3 divided doses. In spite of the lack of information about G-pathogens, meropenem was continued. The patient also received 40 g of commercially available gamma-globulin (intravenous), 8 units of packed red blood cells, 6 units of fresh frozen plasma, and 8 units of platelets. After several days his condition improved, with urine output of 100–150 ml/h and resolution of his metabolic acidosis. On the sixth day, the patient's hemodynamic parameters deteriorated again, with tachycardia to 160 beats per minute and a decrease in blood pressure to 85/60 mmHg. CVVH was administered again for detoxification. On the seventh day, the necrotic tissue was surgically excised (Figures , ). We also noted a progressive decline in the white blood cell count to 2,200/mm3, and administered granulocyte colony stimulating factor.
Cultures of the BAL showed 104 colony-forming units/ml of methycillin resistant Staphylococcus aureus (MRSA). (The patient had been a carrier of methycillin susceptible Staphylococcus aureus [MSSA] isolated from his nose vestibule on admission.) Because MRSA also was present in blood cultures and the patient's condition remained poor, linezolid 1.2 g a day in 2 divided doses was initiated based on additional results of susceptibility tests. After 10 days of intensive treatment, the patient was hemodynamically stable, and we discontinued mechanical ventilation. 25 days after admission the patient was discharged to the trauma surgery ward for plastic reconstruction of his wounds.
The formula for computing Cockcroft-Gault is given by CrCl = ((140 - age) * adjusted weight * (gender_coefficient)) / (serum creatinine * 72), where the gender_coefficient is 1 if male, and 0.85 if female. The serum creatinine concentration is in mg/dL.
The patient's gender is male, which means that the gender coefficient is 1.
The patient is 43 years old. 
The concentration of creatinine is 691.6 µmol/L. We need to convert the concentration to mg/dL. Let's first convert the mass of creatinine from µmol to mg. The mass of creatinine is 691.6 µmol. To convert 691.6 µmol of creatinine to mol, multiply by the conversion factor 1e-06, giving us 691.6 µmol creatinine * 1e-06 mol/µmol = 0.000692 mol creatinine. To convert from mol creatinine to grams, multiply by the molar mass 113.12 g/mol, which will give 0.000692 mol creatinine * 113.12 g/mol = 0.078 g creatinine. To convert 0.078 g of creatinine to mg, multiply by the conversion factor 1000.0, giving us 0.078 g creatinine * 1000.0 mg/g = 78.0 mg creatinine. The current volume unit is L and the target volume unit is dL. The conversion factor is 10.0 dL for every unit of L. Our next step will be to divide the mass by the volume conversion factor of 10.0 to get the final concentration in terms of mg/dL. This will result to 78.0 mg creatinine/10.0 dL = 7.8 mg creatinine/dL. The concentration value of 691.6 µmol creatinine/L converts to 7.8 mg creatinine/dL. 
The formula for computing the patient's BMI is (weight)/(height * height), where weight is the patient's weight in kg and height is the patient's height in m.
The patient's height is 198.0 cm, which is 198.0 cm * 1 m / 100 cm = 1.98 m. The patient's weight is 115.0 kg. The patient's bmi is therefore 115.0 kg / (1.98 m * 1.98 m) = 29.334 kg/m^2.The patient's BMI is 29.3, indicating they are overweight/obese.
Because the patient is overweight/obese, we use the adjusted body weight formula to get the adjusted weight used for Cockroft-Gault Equation. Shown below is the computation for IBW (ideal body weight).
The patient's gender is Male.
The patient's height is 198.0 cm, which is 198.0 cm * 0.393701 in/cm = 77.953 in. 
For males, the ideal body weight (IBW) is calculated as follows:
IBW = 50 kg + 2.3 kg * (height (in inches) - 60)
Plugging in the values gives us 50 kg + 2.3 kg * (77.953 (in inches) - 60) = 91.292 kg.
Hence, the patient's IBW is 91.292 kg.Shown below is the computation for ABW (adjusted body weight).
To compute the ABW value, apply the following formula: ABW = IBW + 0.4 * (weight (in kg) - IBW (in kg)). ABW = 91.292 kg + 0.4 * (115.0 kg  - 91.292 kg) = 100.775 kg. The patient's adjusted body weight is 100.775 kg.

Using the Cockcroft-Gault equation:
CrCl = ((140 - age) * adjusted weight * gender_coefficient) / (serum creatinine * 72).
Plugging the patient's values gives us ((140 - 43) * 100.775 * 1) / (7.8 * 72) = 17.406 mL/min. Hence, the patient's creatinine clearance is 17.406 mL/min.