Crit Care Resusc
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To review the mechanisms of metabolic acidosis in sepsis. ⋯ Understanding the effects of acid-base on the inflammatory response is relevant as all forms of metabolic acidosis appear to be associated with prolonged hospital and ICU length of stay. Since metabolic acidosis is both commonly caused and treated by clinicians, understanding of the physiologic consequences of altered blood pH is imperative.
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To review current concepts in the diagnosis of adrenocortical disease in the critically ill patient. ⋯ We suggest that the following caveats be borne in mind when diagnosing adrenal insufficiency in the critically ill patient. Firstly, the gold standard for the diagnosis has not been established. Secondly, caution must be exercised when interpreting a single plasma cortisol value. In the event of a single result indicating adrenal hypofunction, we suggest repeating the measurements after a 6 to 12 hour interval. The clinician must also be aware of variations in cortisol concentrations induced by the assay. Thirdly, the clinician must be aware of the potential limitations of the conventional high dose corticotrophin test. We also suggest that plasma free cortisol is more relevant than total plasma cortisol in the assessment of adrenal function in critical illness and that the low dose corticotrophin test is more sensitive than the conventional high dose test. These areas should be the subject of further investigations.
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Continuous cardiac output measurement using pulse contour analysis is a technique gaining widespread acceptance in intensive care units. We report a case where a pulse contour analysis computer (PiCCO, Pulsion Medical Systems, Munich, Germany) failed to calibrate in a patient who was undergoing induced hypothermia for anoxic brain injury. ⋯ Subsequent rewarming of the patient allowed calibration of the arterial waveform and continuous cardiac output measurement. We were unable to find any previous reports of this problem using a PiCCO device, although similar problems with thermodilution cardiac output estimation using the pulmonary artery catheter during hypothermic cardiopulmonary bypass have been documented.
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To review methods of quantifying human cerebral autoregulation in health and disease. ⋯ Cerebral autoregulation is impaired with brain injury with cerebral blood flow often becoming pressure-passive. The monitoring and treatment of autoregulatory failure is limited and usually directed at maintaining systemic blood pressure with the effectiveness of this strategy often being unknown.
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To present a rationale for the design of balanced resuscitation and renal replacement crystalloids based on Stewart's physical chemical approach to acid-base. ⋯ A crystalloid SID of 24 mEq/L is 'balanced' for rapid intravenous administration. The 'balanced' SID of renal replacement fluids is likely to be significantly higher, although less than the normal plasma SID of 42 mEq/L.