Metabolic effects of vasoactive agents.

After adequate volume resuscitation, the mainstay of therapy in critically ill patients with shock is treatment with vasoactive substances to restore haemodynamics or to improve regional perfusion. These agents include adrenoceptor agonists with inotropic combined with either vasoconstricting or vasodilating effects, and predominantly vasodilating drugs such as prostacyclin and related compounds. However, vasoactive agents not only affect the cardiovascular system, but also have profound metabolic effects. The interdependence of vasoactive drugs with metabolism may be relevant regarding adequate oxygen and substrate delivery to cover actual organ needs. Therefore, the profiles of these metabolic effects have to be considered during their therapeutic administration.

Assessment of cardiac index in anemic patients.

STUDY OBJECTIVES: During isovolemic hemodilution, healthy individuals maintain oxygen consumption VO2 by identical increases in cardiac index (CI) and oxygen extraction ratio (O(2)ER). In critically ill patients, the relationship between CI and O(2)ER may be different. Patients with an altered cardiac function may have a decreased CI/O(2)ER ratio, whereas patients with sepsis may have an increased CI/O(2)ER ratio. We hypothesized that the analysis of the CI-O(2)ER relationship could help us to assess the adequacy of cardiac function in critically ill patients with anemia. DESIGN: Prospective, observational study. SETTING: Thirty-one-bed medicosurgical ICU of a university hospital. PATIENTS: Sixty patients equipped with arterial and Swan-Ganz catheters presenting with anemia, which was defined as a hemoglobin level < or = 10 g/dL in the absence of active bleeding. Patients were classified into those with compromised cardiac function (group 1; n = 40), and those with normal cardiac function (group 2; n = 20). MEASUREMENTS AND RESULTS: In addition to the pertinent clinical data, initial hemodynamic measurements, including pulmonary artery occlusion pressure (PAOP), CI, and O(2)ER, were collected in all patients at the onset of anemia. As anticipated, group 1 patients (n = 40) had lower CIs, higher O(2)ER levels, and lower CI/O(2)ER ratios than group 2 patients. However, there was no significant difference in PAOP values between the groups. The CI/O(2)ER ratio was < 10 in 27 of 40 group 1 patients but only in 4 of 20 group 2 patients. Of these latter four patients, three were found to be hypovolemic, and one patient with sepsis had severe myocardial depression. There was no statistically significant difference in PAOP in group 2 patients with or without hypovolemia ([mean +/- SD] 12.3+/-2.1 mm Hg) vs 13.7+/-4.3 mm Hg; p = 0.21). In group 1, survivors had a higher CI and CI/O(2)ER ratio than nonsurvivors. In group 2, however, such a relationship did not reach statistical significance. CONCLUSIONS: The relationship between CI and O(2)ER level can help interpret the CI in anemic patients. In anemic patients with no cardiac history, a low CI/O(2)ER ratio (< 10) suggests hypovolemia even when CI is not depressed.

Right diaphragmatic rupture and hepatic hernia: an indirect sign on computed tomography.

We report a case of blunt traumatic right diaphragm rupture with hepatic hernia. The diagnosis was first suggested by an abnormal hepatic location depicted on axial CT. This finding can be considered as a potentially new indirect sign of right diaphragm rupture in patients with blunt trauma. The diagnosis was then confirmed by reformatted CT and MR images.

Effects of vasoactive drugs on gastric intramucosal pH.

OBJECTIVE: To review current knowledge about the effects of vasoactive agents on gastric intramucosal pH (pHi). DATA SOURCES: All studies involving pHi and vasoactive agents were retrieved from a computerized MEDLINE search from 1980 to 1997. We also reviewed the reference lists of all available review articles and primary studies to identify references not found in the computerized searches. STUDY SELECTION: Clinical and experimental studies using dopamine, dopexamine, dobutamine, norepinephrine, epinephrine, nitric oxide, N-acetylcysteine, prostaglandins, or pentoxifylline were considered if splanchnic perfusion and/or pHi measurements were utilized. DATA EXTRACTION: From the selected studies, information was obtained regarding patient population, dosing regimen, duration of study, and effects on splanchnic blood flow (SBF), splanchnic oxygenation, and pHi. DATA SYNTHESIS: Although dopaminergic effects increase SBF, dopamine does not generally increase pHi. Data on the effects of dopexamine on pHi are scarce and inconsistent. Dobutamine can significantly increase SBF and usually increases pHi. In septic patients, norepinephrine seems to increase pHi. Epinephrine may have detrimental effects on gastric perfusion. Prostacyclin seems to increase pHi but data are limited. Insufficient evidence exists to support the beneficial effects of nitric oxide donors or blockers, pentoxifylline, or N-acetylcysteine on pHi. CONCLUSIONS: Overall, the effects of vasoactive agents on pHi are unpredictable. Among the catecholamines, dopamine is the least likely, and dobutamine the most likely, to increase pHi.

Definition and detection of alarms in critical care.

Critical care medicine has developed enormously in complexity and even more so in cost over the past twenty years. There has been evidence of remarkable progress in improved outcomes from some conditions, particularly when severely ill patients are treated in well equipped and well managed intensive care units (ICU) which have clear directorship and comprehensive management guidelines and protocols (Zimmermann et al., Crit Care Med 1993; 21:1443-1451). Nevertheless, for some conditions such as severe acute respiratory failure and multiple organ failure, there is considerable debate as to whether there has been any improvement at all (Lee et al., Thorax 1994; 49:596-597. Artigas et al., Adult respiratory distress syndrome, Churchill Livingstone, Edinbugh, London, Madrid, Melbourne, New York, Tokyo, pp. 509-525). Developments in signal processing and monitoring and recording technology have resulted in a vast increase in the quantity of data that is available to clinicians trying to manage critically ill patients (Price, Bailliere's Clin Anaesthesiol 1987; 1:533-556) but there is little evidence that this apparent gain has lead to better clinical decisions or earlier warning of significant instability. One of the tasks of the European Union sponsored IMPROVE group was to attempt to identify significant downward trends in vital parameters sufficiently early to allow clinical intervention to be potent and effective and ultimately improve patient outcome from a wide range of life threatening conditions. The first stage of this task was to define examples of such life threatening deterioration and conduct a survey in representative intensive care units of the incidence of these conditions and the subsequent patient outcomes. This is a preliminary task, the next stage being the gathering of "real time' data from critically ill patients for 24-h sample periods to probe for deteriorating trends and to compile a comprehensive annotated data library of physiological data as a rich resource for future adaptations in signal processing technology and clinical decision support.