Critical care medicine
-
Critical care medicine · Oct 1992
Myocardial metabolism and adaptation during extreme hemodilution in humans after coronary revascularization.
This study was designed to evaluate the oxygen transport adjustments and myocardial metabolic adaptation that occurs with different levels of hemodilution during normothermia after cardiopulmonary bypass. ⋯ Hemodilution to a hematocrit of approximately 15% is tolerated in anesthetized humans after coronary artery bypass surgery. There was no evidence of myocardial ischemia, as demonstrated by absence of S-T depression on the electrocardiogram, lactate extraction, or hypoxanthine release. In selected patients, postoperative transfusion may be based on systemic physiologic end-points, such as oxygen extraction ratio, rather than set hematocrit values.
-
Critical care medicine · Oct 1992
Effect of extracorporeal membrane oxygenation on tobramycin pharmacokinetics in sheep.
Critically ill infants undergoing extracorporeal membrane oxygenation (ECMO) therapy often receive multiple pharmacologic agents. Although the disposition of many drugs has been assessed in patients undergoing cardiopulmonary bypass and in patients receiving mechanical ventilation, only limited data exist for selected medications in patients undergoing ECMO. To evaluate the potential influence of ECMO on aminoglycoside pharmacokinetics, we studied the disposition of tobramycin in ten sheep before and during ECMO therapy. Each sheep received a single iv dose of tobramycin during a control period before ECMO and on a study day during ECMO. Identically timed serial blood samples over 4 hrs were obtained after each tobramycin dose. Paired serum tobramycin concentrations were obtained pre- and postmembrane oxygenator during ECMO in six sheep. ⋯ These data suggest that ECMO circuitry does not sequester tobramycin and that the prolonged elimination half-life observed during ECMO therapy is not due to a change in drug clearance but is due to an ECMO-induced increase in tobramycin volume of distribution. To achieve and maintain preselected target tobramycin serum concentrations during ECMO, the usual dosage interval should remain unchanged, but the dose should be increased to compensate for the alteration in the drug's volume of distribution. The clinical applicability of these findings needs to be confirmed in carefully controlled clinical studies involving infants receiving ECMO therapy.
-
Critical care medicine · Oct 1992
Comparative StudyInfectious and mechanical complications of central venous catheters placed by percutaneous venipuncture and over guidewires.
To compare the frequency of infectious and mechanical complications of central venous and pulmonary artery catheters placed by initial venipuncture vs. over a guidewire at existing sites. ⋯ When prolonged central venous or pulmonary artery catheterization is necessary, periodic catheter replacement over a guidewire is associated with fewer mechanical complications than initial venipuncture. Periodic catheter replacement over a guidewire is also associated with no increase in risk of infection.
-
Critical care medicine · Oct 1992
Historical ArticleCare of the dying: an ethical and historical perspective.
To provide a historical perspective, from ancient Greece to the middle of the 20th century, on ethical issues and principles commonly associated with medical care for the dying in Western civilization. ⋯ Ethical debates regarding appropriate care for the dying are as old as medicine itself. Although beneficent concerns have characterized the medical community in almost every period of history, tensions have repeatedly arisen as diverse religious and philosophical ideologies have produced varying standards to define such beneficence. In the Christian world, the sanctity of life was often extolled as the paramount standard. For the ancient Greeks and Romans, and again in many post-Renaissance philosophies, quality of life considerations assumed equal or greater importance. Modern life-prolonging technologies heighten the debate by allowing these two standards to dramatically conflict, particularly in the critical care setting.
-
Critical care medicine · Oct 1992
Comparative StudyFibrinolytic activity in bronchoalveolar lavage of baboons with diffuse alveolar damage: trends in two forms of lung injury.
Alveolar fibrin deposition is prominent in diffuse alveolar damage, the morphologic hallmark of the adult respiratory distress syndrome. To determine if a persistent abnormality of fibrin clearance occurs in the alveolar compartment during evolving diffuse alveolar damage, we characterized abnormalities of fibrin turnover in serial bronchoalveolar lavage specimens from two baboon models: a) diffuse alveolar damage induced by 80% oxygen and bronchoscopic seeding of Pseudomonas aeruginosa; and b) a more fulminant form of diffuse alveolar damage induced by bronchoscopic seeding of Pseudomonas and the infusion of oleic acid. ⋯ These data indicate that while increased procoagulant activity is characteristic of evolving diffuse alveolar damage and favors alveolar fibrin deposition, fibrinolytic activity may be transiently diminished or remain intact during evolving diffuse alveolar damage in baboons.