Severe sepsis

A 69-year-old, 80 kg male is admitted to the intensive care unit with respiratory failure

secondary to a lower respiratory tract infection. He has his trachea intubated and

mechanical ventilation of the lungs is commenced. He has a PiCCO cardiac output

monitor sited; an internal jugular central venous catheter and urinary catheter are

also inserted. He receives antibiotics, intravenous fluid resuscitation and an infusion

of noradrenaline. Three hours following admission to hospital, some of his clinical

measurands are as follows: heart rate 110 bpm; mean arterial blood pressure

66mmHg; central venous pressure 10 mmHg; arterial oxygen saturation 93%; central

venous oxygen saturation 68%; cardiac index 2.5 L/min per m2; urine output

30 mL/h; pH 7.23; PaCO2 6.0 kPa; PaO2 9.1 kPa; HCO3

– 19 mmol/L; base excess

−6.2 mmol/L; lactate 3.2 mmol/L; haematocrit 0.31; FiO2 0.7; MV 7.2 L/min; plateau

pressure 29cmH2O. Which one of the following should be prioritised for the patient

to receive NEXT?

a) Increased rate of noradrenaline infusion

b) Dobutamine infusion

c) Further intravenous fluid

d) Infusion of packed red cells

e) Increased minute ventilation

Answer: c

Explanation

During the management of septic shock, mechanically ventilated patients should have

a higher target central venous pressure: 12 to 15mmHg whereas the target would be

8 to 12mmHg in spontaneously ventilating patients. Low central venous pressure

should prompt a fluid challenge of crystalloid or colloid. This may increase this

patient’s cardiac output sufficiently to increase his central venous pressure, urine

output (to >0.5 mL/kg/h) and central venous oxygen saturation (to >70%). A mean

arterial pressure of >65mmHg is adequate and the noradrenaline need not be

increased, as to do so may jeopardise microvascular flow. Dobutamine may be introduced

if the cardiac output is low (as manifest via a number of indicators) and filling

pressures are elevated but supranormal levels should not be targeted. Red cells may be

transfused to maintain a haemoglobin concentration of >7 g/dL or a haematocrit of

>0.3 but not before, unless there are mitigating circumstances. Increasing minute

ventilation may risk increasing plateau pressure above 30cmH2O, further increasing

the likelihood of acute respiratory distress syndrome. Permissive hypercapnia is

acceptable where the pH is not grossly deranged. The candidate should be familiar

with the 2008 surviving sepsis guidelines (see below).

Reference

Dellinger RP, Levy MM, Carlet JM et al. Surviving Sepsis Campaign: International

guidelines for management of severe sepsis and septic shock: 2008. Crit Care Med 2008;

36(1): 296–327.