Effect of oxygen affinity and molecular weight of HBOCs on cerebral oxygenation and blood pressure in rats.

Purpose: This study assessed the effect of oxygen affinity and molecular weight (MW) of o-raffinose cross-linked hemoglobin based oxygen carriers (HBOCs) on cerebral oxygen delivery and mean arterial blood pressure (MAP) following hemorrhage and resuscitation in rats.

Methods: Isoflurane anesthetized rats (n = 6-7 per group) underwent 30% hemorrhage and resuscitation with an equivalent volume of one of three different HBOCs: 1) High P50 Poly o-raffinose hemoglobin (Poly OR-Hb, P50 = 70 mmHg); 2) High P50 > 128 Poly OR-Hb (MW > 128 kDa, P50 = 70 mmHg) and 3) Low P50 > 128 Poly OR-Hb (MW >128 kDa, P50 = 11 mmHg). Hippocampal cerebral tissue oxygen tension, regional cerebral blood flow (rCBF), MAP, total hemoglobin concentration and arterial blood gases were measured.

Increased expression of HIF-1alpha, nNOS, and VEGF in the cerebral cortex of anemic rats.

This study tested the hypothesis that specific hypoxic molecules, including hypoxia-inducible factor-1alpha (HIF-1alpha), neuronal nitric oxide synthase (nNOS), and vascular endothelial growth factor (VEGF), are upregulated within the cerebral cortex of acutely anemic rats. Isoflurane-anesthetized rats underwent acute hemodilution by exchanging 50% of their blood volume with pentastarch. Following hemodilution, mean arterial pressure and arterial Pa(O(2)) values did not differ between control and anemic rats while the hemoglobin concentration decreased to 57 +/- 2 g/l.

Beta2 adrenergic antagonist inhibits cerebral cortical oxygen delivery after severe haemodilution in rats.

Background: Haemodilution has been associated with neurological morbidity in surgical patients. This study tests the hypothesis that inhibition of cerebral vasodilatation by systemic beta2 adrenergic blockade would impair cerebral oxygen delivery leading to tissue hypoxia in severely haemodiluted rats.

Methods: Under general anaesthesia, cerebral tissue probes were placed to measure temperature, regional cerebral blood flow (rCBF) and tissue oxygen tension (P(Br)O2) in the parietal cerebral cortex or hippocampus.

Factors affecting perioperative transfusion decisions in patients with coronary artery disease undergoing coronary artery bypass surgery.

Background: A high proportion of patients having cardiac bypass surgery receive erythrocyte transfusions. Decisions about when to transfuse patients having surgery for coronary artery disease may impact on erythrocyte utilization and patient morbidity and mortality. There are no published data about the factors that influence physicians' decisions to transfuse erythrocytes to these patients.

Case report: profound hypotension associated with labetalol therapy in a patient with cerebral aneurysms and subarachnoid hemorrhage.

Purpose: Labetalol is an effective antihypertensive medication frequently used to treat systemic hypertension in acute care settings, including the management of hypertension associated with a subarachnoid hemorrhage. We present a case of profound hypotension, refractory to inotropic and vasopressor therapy following an iv infusion of labetalol.

Clinical Features: Initiation of an iv labetalol infusion resulted in good blood pressure control in a patient suffering from a Fisher grade 3 subarachnoid hemorrhage with an initial Glascow coma scale of 14/15 and mild hydrocephalus.

Two-year outcomes, health care use, and costs of survivors of acute respiratory distress syndrome.

Rationale: Little is known about the long-term outcomes and costs of survivors of acute respiratory distress syndrome (ARDS).

Objectives: To describe functional and quality of life outcomes, health care use, and costs of survivors of ARDS 2 yr after intensive care unit (ICU) discharge.

Methods: We recruited a cohort of ARDS survivors from four academic tertiary care ICUs in Toronto, Canada, and prospectively monitored them from ICU admission to 2 yr after ICU discharge.

Treatment of pulmonary hypertension with selective pulmonary vasodilators.

Purpose Of Review: Pulmonary vasodilators are important in the management of pulmonary hypertension. Although systemic vasodilators may be effective in lowering pulmonary artery pressure, systemic vasodilation is the main limitation to dose titration. This review summarizes the latest research and developments in pulmonary vasodilators in the management of acute and chronic pulmonary hypertension.

Natural course of left atrial thrombi after bioprosthetic mitral valve replacement in a patient with heparin-induced thrombocytopenia.

Left atrial (LA) clots involving prosthetic mitral valves are unusual complications of heparin-induced thrombocytopenia (HIT), and little is known about their natural history. A 73-year-old woman underwent bioprosthetic mitral valve replacement, which was complicated by atrial fibrillation and LA thrombus due to HIT. She was treated medically and followed up for 18 months.

Increased cerebral tissue oxygen tension after extensive hemodilution with a hemoglobin-based oxygen carrier.

Transfusion of anemic patients with hemoglobin-based oxygen carriers (HBOCs) may improve cerebral oxygen delivery. Conversely, cerebral vasoconstriction, associated with HBOC transfusion, could limit optimal cerebral tissue oxygenation. We hypothesized that hemodilution with a HBOC would maintain cerebral tissue oxygenation, despite the occurrence of cerebral vasoconstriction.

Comparison of bolus remifentanil versus bolus fentanyl for induction of anesthesia and tracheal intubation in patients with cardiac disease.

Objective: Large bolus-dose remifentanil may be advantageous for use during induction of anesthesia because of its short duration of effect. Currently, there are little data on the use of large bolus-dose remifentanil because of reports of severe bradycardia and hypotension. The purpose of this study is to compare the hemodynamic effects of bolus remifentanil versus fentanyl with glycopyrrolate for induction of anesthesia in patients with heart disease.

A multicenter risk index for atrial fibrillation after cardiac surgery.

Context: Atrial fibrillation is a common, but potentially preventable, complication following coronary artery bypass graft (CABG) surgery.

Objectives: To assess the nature and consequences of atrial fibrillation after CABG surgery and to develop a comprehensive risk index that can better identify patients at risk for atrial fibrillation.

Design, Setting, And Participants: Prospective observational study of 4657 patients undergoing CABG surgery between November 1996 and June 2000 at 70 centers located within 17 countries, selected using a systematic sampling technique.

A phase II dose-response study of hemoglobin raffimer (Hemolink) in elective coronary artery bypass surgery.

Background: We performed this study to determine the dose-response of hemoglobin raffimer administered in conjunction with intraoperative autologous donation in patients undergoing coronary artery bypass grafting surgery. A secondary objective was to evaluate hemoglobin raffimer for reducing the incidence of allogeneic red blood cell transfusions.

Methods: This was a phase II, single-blind, multicenter, placebo-controlled, open-label study.

Hypercapnia increases cerebral tissue oxygen tension in anesthetized rats.

Purpose: To test the hypotheses that deliberate elevation of PaCO(2) increases cerebral tissue oxygen tension (PBrO(2)) by augmenting PaO(2) and regional cerebral blood flow (rCBF).

Methods: Anesthetized rats were exposed to increasing levels of inspired oxygen (O(2)) or carbon dioxide (CO(2); 5%, 10% and 15%, n = 6). Mean arterial blood pressure (MAP), PBrO(2) and rCBF were measured continuously.

Dynamic characteristics of cerebral lipid microemboli: videomicroscopy studies in rats.

Unlabelled: Cerebral lipid microemboli (LME) may cause postoperative cognitive dysfunction after orthopedic and cardiovascular surgery. In 13 anesthetized rats, we created a cranial window to study LME using orthogonal polarization spectral imaging videomicroscopy. All rats received 0.

Successful treatment using recombinant factor VIIa for severe bleeding post cardiopulmonary bypass.

Purpose: To describe a case of persistent and excessive bleeding following an aortic valve and ascending aorta replacement that was successfully managed with recombinant factor VIIa (rFVIIa). The postulated mechanisms for rFVIIa are discussed.

Clinical Features: A 75-yr-old female with no preoperative coagulopathy underwent a tissue aortic valve replacement and supracoronary ascending aorta replacement for severe aortic stenosis and an ascending aortic aneurysm.

One-year outcomes in survivors of the acute respiratory distress syndrome.

Background: As more patients survive the acute respiratory distress syndrome, an understanding of the long-term outcomes of this condition is needed.

Methods: We evaluated 109 survivors of the acute respiratory distress syndrome 3, 6, and 12 months after discharge from the intensive care unit. At each visit, patients were interviewed and underwent a physical examination, pulmonary-function testing, a six-minute-walk test, and a quality-of-life evaluation.

Hemodilutional anemia is associated with increased cerebral neuronal nitric oxide synthase gene expression.

Severe hemodilutional anemia may reduce cerebral oxygen delivery, resulting in cerebral tissue hypoxia. Increased nitric oxide synthase (NOS) expression has been identified following cerebral hypoxia and may contribute to the compensatory increase in cerebral blood flow (CBF) observed after hypoxia and anemia. However, changes in cerebral NOS gene expression have not been reported after acute anemia.

PVC tracheal tubes exert forces and pressures seven to ten times higher than silicone or armoured tracheal tubes--an in vitro study.

Purpose: Many types of tracheal tubes (TT) including silicone, polyvinylchloride (PVC) and armoured have been used for blind tracheal intubation (TI) via the intubating laryngeal mask airway (ILMA) and may cause trauma to the airway. We examined the maximal in vitro forces and pressures exerted by the tip of various TT as it exits the ILMA.

Methods: Silicone, PVC and armoured TT were studied.

Right heart obstruction from a balloon-like sinus of Valsalva aneurysm in a patient with Down syndrome.

A 40-year-old man with Down syndrome presented with right heart failure. He was markedly obese and had severe developmental delay. There was marked edema and an early diastolic sound.

Survey of the members of the cardiovascular section of the Canadian Anesthesiologists' Society on the use of perioperative transesophageal echocardiography - a brief report.

Purpose: Transesophageal echocardiography (TEE) is a useful diagnostic and monitoring tool in the operating room. In the United States, an increasing number of centres are training anesthesiologists to preform intraoperative TEE. In Canada, TEE has been slow to gain acceptance as an intraoperative monitor and little information is available on its use by the anesthesiologists across the country.

Effect of NaHCO3 on cardiac energy metabolism and contractile function during hypoxemia.

Objective: To examine the impact of administration of NaHCO3 on contractility and energy metabolism of the myocardium during hypoxemia.

Methods: Regional myocardial hypoxia was induced in the left anterior descending (LAD) artery myocardium in anesthetized, open-chest dogs, using a perfusion circuit between the right atrium and the LAD artery, and a membrane oxygenator. The rate of flow in LAD artery was maintained constant with the use of a roller pump.

Distribution of pulmonary blood flow in the perfluorocarbon-filled lung.

Objective: Partial liquid ventilation (PLV) improves gas exchange in animal studies of lung injury. Perfluorocarbons (PFCs) are heavy liquids and are therefore preferentially delivered to the most dependent areas of lung. We hypothesised that improved oxygenation during PLV might be the consequence of a redistribution of pulmonary blood flow away from poorly ventilated, dependent alveoli, leading to improved ventilation/perfusion (V/Q) matching.