The hard signs indicating SIRS should be sought (Table 1); however, most patients in ICUs satisfy these criteria and their non-specific nature makes them unhelpful for clinical management. There may be evidence of depleted intravascular volume with dry mucous membranes and low jugular venous pressure. There may be mild icterus, bruising, prolonged bleeding from venous puncture sites, and slow wound healing. Patients may look surprisingly well, with warm extremities, venous distension, and bounding peripheral pulses, or they may look quite ill, with cool and cyanosed peripheries. These two presentations are the extremes of a spectrum and represent the descriptions of 'cold' and 'warm' shock found in older textbooks. Occasionally the patient may be virtually moribund at first presentation, when findings will be of cold poorly perfused peripheries, thready peripheral pulses, and cyanosis; blood pressure will be difficult to measure, respiratory rate is usually raised, and the patient will be comatose.
Examination of the cardiovascular system usually reveals a mild tachycardia; blood pressure, particularly diastolic pressure, is slightly lower than that previously recorded. If there is excessive arterial vasoconstriction, the systolic pressure can occasionally be raised in an attempt to compensate for intravascular volume depletion. The jugular venous pressure is usually low, but if the heart is failing or there is compensatory vasoconstriction it may be raised. There may be added heart sounds, such as a gallop rhythm, and occasionally a flow murmur if the patient has a hyperdynamic circulation. Assessment of the respiratory system demonstrates a raised respiratory rate, and as lung injury and fluid extravasation become more extensive there may be reduced respiratory excursion, basal crackles, and evidence of pleural effusions. It is quite common for the cardiorespiratory findings to be diagnosed erroneously as left ventricular failure, and for the patient to be treated with diuretics; however, if the underlying condition involves volume depletion, this will worsen the perfusion deficit. Further investigations to identify and correct the physiological abnormalities are always necessary.
The abdominal examination may show evidence of reduced gastrointestinal function with distension, absent bowel sounds, and large nasogastric tube output. Signs of central nervous system abnormalities include reduced level of consiousness and confusion or psychosis.
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