Biomedical subjects

William C Oliver

Publications and source records attributed to William C Oliver.

14 recordsLinked to original sources

PubMed2007

A prospective study on anesthesia machine fault identification.

BACKGROUND: Although few studies have been performed recently, several have suggested that some practitioners are not well able to detect preset anesthesia machine faults. METHODS: We performed a prospective study to determine whether there is a correlation between duration of anesthesia practice and the ability to detect anesthesia machine faults. Our hypothesis was that more anesthesia practice would increase the ability to detect anesthesia machine faults. This study was performed during a nationally attended anesthesia meeting held at a large academic medical center, where 87 anesthesia providers were observed performing anesthesia machine checkouts. The participants were asked to individually check out an anesthesia machine with an unspecified number of preset faults. The primary outcome measures were the written listing of faults detected during an anesthesia machine checkout. RESULTS: Of the five faults preset into the test machine, participants with 0-2 yr experience detected a mean of 3.7 faults, participants with 2-7 yr experience detected a mean of 3.6 faults, and participants with more than 7 yr experience detected a mean of 2.3 faults (P < 0.001). CONCLUSIONS: Our prospective study demonstrated that anesthesia machine checkout continues to be a problem.

Anesthesiology↗

PubMed2006

A prospective, randomized platelet-function study of heparinized oxygenators and cardiotomy suction.

OBJECTIVE: The purpose of this study was to determine if substitution of a heparin-coated oxygenator and salvaged autologous blood for cardiotomy suction would improve platelet function. DESIGN: A prospective, randomized trial. SETTING: A large academic medical center. PARTICIPANTS: Sixty adult patients undergoing coronary artery bypass graft surgery with cardiopulmonary bypass (CPB). INTERVENTIONS: Patients were randomized into 1 of 4 groups in a 2 x 2 factorial design by oxygenator (heparinized v nonheparinized) and blood salvage during CPB (cardiotomy suction v salvaged autologous blood). MEASUREMENTS AND MAIN RESULTS: Primary outcome measures were platelet function, glass-bead retention, platelet dense-body adenosine triphosphate secretion, platelet-rich plasma (PRP) aggregometry, Plateletworks platelet-function analyzer (Helena Laboratories Corp, Allen Park, MI), and platelet count. Secondary outcome measures were chest-tube drainage and allogeneic blood transfusion requirements. All platelet-function tests except thrombin-receptor activator peptide-induced PRP aggregometry showed a reduction in platelet function during and immediately after CPB (all p < 0.05). The only statistically significant difference in platelet-function tests between the groups was the glass-bead assay at 5 minutes before discontinuation of CPB (p < 0.05). This difference resolved 10 minutes after protamine administration. There were no differences between the groups in the amount of blood transfused, chest-tube drainage, and routine laboratory test results. CONCLUSIONS: The authors concluded that the effects of these changes to the CPB circuit were small and inconsequential in this cohort of patients.

Adult↗

PubMed2006

Excessive bleeding and transfusion in a prior cardiac surgery is associated with excessive bleeding and transfusion in the next surgery.

If there is a genetic predisposition to excessive bleeding, there should be an association in excessive blood loss between multiple cardiac surgeries. We retrospectively determined in 174 patients the association of excessive bleeding between 2 cardiac surgeries with cardiopulmonary bypass between January 19, 1990 and June 25, 2002. Excessive bleeding was defined by 2 criteria: (a) postoperating room chest tube blood loss over 24 h more than or equal to 750 mL (chest tube drainage [CTD] > or = 750) and (b) transfusion of any non-red blood cell (RBC) blood products. Logistic regression was used to estimate the association between excessive bleeding at the first and second cardiac procedures. The logistic regression models for CTD > or = 750 in the second surgery determined that CTD > or = 750 in the first surgery compared to CTD < 750 had an unadjusted odds ratio of 2.18 (P = 0.03) and an odds ratio of 2.42 (P = 0.03) when adjusted for age, sex, body surface area, preoperative anticoagulant use, cardiopulmonary bypass duration, and procedure type at second surgery. The logistic regression model for any non-RBC use in the second surgery determined that any non-RBC use in the first surgery compared with no non-RBC use had an unadjusted odds ratio of 2.32 (P = 0.02) and an odds ratio of 2.55 (P = 0.02) when adjusted for age, sex, body surface area, preoperative anticoagulant use, cardiopulmonary bypass duration, and procedure type at second surgery. We conclude that a history of excessive bleeding during the first operation is associated with more than two times increased risk for excessive bleeding in the second surgery.

Adult↗

PubMed2006

A comparison of fenoldopam with dopamine and sodium nitroprusside in patients undergoing cross-clamping of the abdominal aorta.

Fenoldopam, a selective dopamine-1-receptor agonist, decreases arterial blood pressure rapidly, with a brief duration of action similar to sodium nitroprusside (SNP), but in contrast to SNP, it increases renal blood flow. We compared the hemodynamic and renal effects of fenoldopam in patients undergoing abdominal aortic surgery requiring cross-clamping of the aorta with another therapeutic option, dopamine and SNP. Fenoldopam or 2 mcg x kg(-1) x min(-1) of dopamine and SNP was infused before incision in 60 randomly selected patients in a double-blind fashion. Hemodynamic variables were recorded before incision, immediately before clamping the aorta, 5 min after cross-clamp release and upon completion of surgery. Urine output, serum creatinine, and creatinine clearance were measured intraoperatively and postoperatively. Characteristics were compared between groups using two-sample rank sum test for continuous variables and Fisher's exact test for discrete variables. The occurrence of severe hypotension, maximum systolic blood pressure, and need for additional antihypertensive drugs were not different between the groups. Most intraoperative hemodynamic variables and all indices of renal function did not differ according to treatment. Therefore, fenoldopam has no therapeutic advantage compared with similar therapies in patients undergoing major vascular surgery involving cross-clamping of the aorta.

Aged↗

PubMed2005

Can N-acetylcysteine reverse the antiplatelet effects of clopidogrel? An in vivo and vitro study.

BACKGROUND: The active metabolite of clopidogrel binds the P2Y12 ADP receptor on the platelet surface via a disulfide bond. N-Acetylcysteine (NAC) is able to reduce disulfide bonds. We postulated that NAC might reverse clopidogrel's effect on platelets. METHODS: Two groups of patients were investigated. Group 1 included 11 patients with stable coronary disease who, after discontinuation of aspirin, received 14 days of clopidogrel, 75 mg/day. Bleeding time and whole-blood platelet aggregometry (with 5 micromol/L ADP) were compared before and after the 14 days. Patients were then treated with 6 g of NAC orally, followed by repeat measurement of bleeding time and aggregometry. In group 2, 14 patients were treated with clopidogrel (300 mg) and aspirin before a percutaneous coronary intervention. Blood was drawn 22 +/- 3 hours later and divided into 2 samples. One was sent immediately for platelet-rich plasma aggregometry (using 5 and 2 micromol/L ADP, collagen, and arachidonic acid as agonists), thromboelastography, and aggregometry using the Plateletworks assay (Helena Laboratories, Beaumont, Tex). The other sample was treated with NAC (500 mg/L), after which these same platelet function tests were performed. RESULTS: In group 1, NAC therapy did not significantly change the bleeding time or results of aggregometry. In group 2, neither aggregometry nor the Plateletworks assay suggested reversal of inhibition by NAC. CONCLUSIONS: These studies reveal that a large dose of NAC does not reduce inhibition of platelet aggregation by clopidogrel in vitro or in vivo.

Acetylcysteine↗

PubMed2005

An in vitro study comparing the effects of Hextend, Hespan, normal saline, and lactated ringer's solution on thrombelastography and the activated partial thromboplastin time.

OBJECTIVE: The purpose of this study was to determine if 6% HES 450/0.7 (hydroxyethyl starch 450/0.7) in normal saline (Hespan) and 6% HES 450/0.7 in lactated Ringer's solution (Hextend) have the same inhibition of the intrinsic coagulation pathway and platelet function. Multiple studies have suggested that 6% Hespan inhibits coagulation and increases chest tube drainage and transfusion requirements in cardiac surgical patients. There have been few studies of the effects of 6% Hextend, a relatively new plasma volume expander, on coagulation and the results thus far have been mixed. DESIGN: A prospective in vitro study. SETTING: A large academic medical center. PARTICIPANTS: Blood was collected from 30 healthy volunteers. Interventions : The blood was fractionated and diluted by 30% with Hextend, Hespan, normal saline, and lactated Ringer's solutions, with a native sample for a control. MEASUREMENTS AND MAIN RESULTS: Primary outcome measures were thromboelastography and activated partial thromboplastin time (APTT). For each of the TEG parameters, there was no difference between samples diluted with Hextend compared with Hespan (p > or = 0.112 in all cases). APTT did not differ significantly between samples diluted with Hextend compared with Hespan (p = 0.562). CONCLUSIONS: This prospective in vitro study suggests that Hextend and Hespan, hydroxyethyl starch 450/0.7 in different base solutions, exhibit the same effect on platelet function as measured by the TEG.

Adult↗

PubMed2004

Variability of plasma aprotinin concentrations in pediatric patients undergoing cardiac surgery.

OBJECTIVES: Infants and children undergoing cardiopulmonary bypass for repair of congenital heart defects are at substantial risk for excessive bleeding, contributing greatly to morbidity and mortality. Aprotinin significantly reduces bleeding and transfusion requirements in adults but is of indeterminate value for pediatric patients. The aim of this study was to determine plasma aprotinin concentrations in these patients with a functional aprotinin assay. METHODS: Thirty patients less than 16 years of age scheduled for cardiac surgery with aprotinin were enrolled. Aprotinin was administered as a 25,000 KIU/kg bolus, 35,000 KIU/kg cardiopulmonary bypass prime, and 12,500 KIU.kg(-1).h(-1) continuous infusion. Blood samples for aprotinin concentrations (kallikrein-inhibiting units/milliliter) were obtained before aprotinin; 5 minutes post-bolus; 5 minutes after cardiopulmonary bypass initiation; 30 and 60 minutes on cardiopulmonary bypass; on discontinuation of aprotinin; 1 hour after aprotinin discontinuation; and 4 hours after permanent separation from cardiopulmonary bypass. For analysis, patients were grouped according to weight (<10 kg, 10-20 kg, >20 kg). Differences between weight groups were assessed using an exact test for categoric variables and 1-way analysis of variance for continuous variables. RESULTS: Aprotinin concentrations differed significantly across weight groups. Five minutes after aprotinin bolus and initiation of cardiopulmonary bypass, there was significant correlation between weight and aprotinin concentration (r =.57, P =.003; r =.69, P =.001, respectively). CONCLUSION: A functional assay reveals significant variability in aprotinin concentration for pediatric patients using current weight-based aprotinin dosing. Additional investigation is necessary to determine target aprotinin concentration dosing regimens to provide better efficacy.

Adolescent↗

PubMed2004

Hemofiltration but not steroids results in earlier tracheal extubation following cardiopulmonary bypass: a prospective, randomized double-blind trial.

BACKGROUND: Activation of the inflammatory cascade is thought to account for some of the respiratory dysfunction and prolonged mechanical ventilation associated with cardiopulmonary bypass. The objective of this investigation was to identify whether perioperative steroids or hemofiltration during cardiopulmonary bypass, by their attenuation of inflammation, would reduce duration of mechanical ventilation after cardiac surgery. METHODS: After Institutional Review Board approval and informed consent, 192 patients scheduled to undergo elective primary coronary artery bypass grafting or valvular replacement or repair were randomized in a double-blind prospective study into three groups. One group (Control) received saline at induction and at 6-h intervals for four doses. Another group (Hemofil) received saline and hemofiltration to obtain 27 ml/kg of hemofiltrate. The final group (Steroid) received 1 g methylprednisolone before anesthesia induction and then 4 mg of dexamethasone at 6-h intervals for four doses. All patients underwent normothermic cardiopulmonary bypass and received propofol for postoperative sedation. Separate two-sample comparisons were performed to compare each experimental group versus the control group using the Wilcoxon rank sum test for continuous variables and Fisher exact test for categorical variables. In all cases, two-tailed P values </= 0.05 were considered statistically significant. RESULTS: The median time until the patient reached an intermittent mandatory ventilation of 4/min (258.5 versus 385.0 min, respectively; P = 0.02) and tracheal extubation (352.0 versus 518.0 min; P = 0.03) was significantly reduced for group Hemofil but no different for Steroid compared to Control. CONCLUSIONS: Hemofiltration and steroids are both previously reported to attenuate the inflammatory response but only hemofiltration reduced time to tracheal extubation for adults after cardiopulmonary bypass in this study.

Aged↗

PubMed2004

Morbidity and mortality in the use of electroconvulsive therapy.

There are a few large studies of the morbidity and mortality of electroconvulsive therapy (ECT). To add data to this literature, we performed a retrospective review of all the patients who underwent ECT at our institution between January 1, 1988, through December 31, 2001. We identified 2,279 patients who were given 17,394 ECT treatments during their first series. The median number of treatments received per patient was 7. Twenty-one patients (0.92%) experienced a complication at some time during their first series of ECT treatments. Cardiac complications, mostly arrhythmias, constituted the majority. However, none of the complications caused permanent injury, and none of the patients died during or immediately after ECT. There were 18 deaths within 30 days of the final treatment, none related to ECT. These data are concordant with those of other published large series, and we conclude that ECT is an extremely safe procedure.

Adult↗

PubMed2003

Blood loss in infants and children for open heart operations: albumin 5% versus fresh-frozen plasma in the prime.

BACKGROUND: Infants and children undergoing cardiopulmonary bypass become substantially hemodiluted secondary to the volume used to prime the oxygenator. Fresh-frozen plasma has been included in the prime to lessen dilution of clotting factors and correspondingly minimize blood loss and transfusions. METHODS: We prospectively randomized 56 patients weighing 10 kg or less who required cardiopulmonary bypass to receive either one unit of fresh-frozen plasma or 200 mL of albumin 5% in the prime. After protamine administration, samples for prothrombin time, fibrinogen, platelet count, and thromboelastogram were obtained. Mediastinal chest tube drainage and transfusion requirements were documented. RESULTS: There were no significant differences between groups regarding demographic or surgical characteristics. Blood loss during the first 24 hours was similar in both groups, but total transfusions were significantly greater in those who received fresh-frozen plasma instead of albumin 5% in the prime (8.0 +/- 4.2 versus 6.1 +/- 4.5 U, respectively; p = 0.035). Post hoc analyses suggest that for cyanotic patients and patients undergoing complex operations, fresh-frozen plasma in the prime results in less blood loss than albumin 5%. CONCLUSIONS: Substitution of albumin 5% for fresh-frozen plasma in the prime of acyanotic patients weighing 10 kg or less who undergo noncomplex operations requiring cardiopulmonary bypass significantly reduces perioperative transfusions without increasing blood loss. Further investigation is needed to determine whether increased blood loss is associated with increased transfusions when albumin 5% is substituted for fresh-frozen plasma in the prime of infants and children who are cyanotic or undergoing complex operations.

Blood Coagulation Tests↗

PubMed2003

A comparison of bleeding and transfusion in patients who undergo coronary artery bypass grafting via sternotomy with and without cardiopulmonary bypass.

OBJECTIVE: To determine whether there is a difference between on-pump cardiopulmonary bypass (CABG) and off-pump coronary artery bypass grafting (OPCAB) without heparin reversal with regard to bleeding, transfusion requirements, and incidence of surgical re-exploration of the mediastinum. DESIGN: Retrospective chart review. SETTING: A large academic medical center. PARTICIPANTS: Two hundred adult patients undergoing cardiac surgery. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: One hundred CABG patients were compared with 100 OPCAB patients. Statistical significance was measured with P values of <or=0.05. The heparin was not reversed in the OPCAB patients. CABG patients received more intraoperative allogeneic red blood cells (median 250 mL v 0 mL, p = 0.002), intraoperative autotransfusion (IAT) (550 mL v 425 mL, p = 0.001), platelets (9% v 1%, p = 0.009), and less albumin (0 mL v 250 mL, p = 0.001) than OPCAB patients. Postoperatively, CABG patients were more likely to receive fresh-frozen plasma (19% v 8%, p = 0.03) and less likely to receive IAT than the OPCAB group. During the initial 4-hour postoperative period, OPCAB patients exhibited greater blood loss via chest tube (290 mL v 385 mL, p = 0.003); however, at 12 hours and 24 hours postoperatively, there was no statistical difference in blood loss between the 2 groups. There were no statistically significant differences in surgical re-exploration of the mediastinum between the CABG and OPCAB groups. CONCLUSION: Despite not reversing the heparin at the end of the OPCAB surgery, OPCAB surgery was associated with an overall reduction in allogeneic transfusion requirements.

Aged↗

PubMed2003

Heparin-coated versus uncoated extracorporeal circuit in patients undergoing coronary artery bypass graft surgery.

OBJECTIVE: To assess the effect of heparin-coated circuits on bleeding, transfusion, and platelet count in patients undergoing primary coronary artery bypass grafting with full heparinization. DESIGN: Randomized, double-blind study. SETTING: Tertiary-care academic medical center. PARTICIPANTS: Eighty-eight patients undergoing coronary artery bypass grafting requiring cardiopulmonary bypass (CPB) without previous sternotomy. INTERVENTIONS: Subjects received either a heparin-coated or an uncoated extracorporeal circuit for CPB. Heparin, 300 micro/kg, was administered, and supplemental amounts were administered to maintain an activated coagulation time of greater than 480 seconds. Platelet counts were determined during CPB. Mediastinal chest tube drainage was collected in the intensive care unit for 24 hours. MEASUREMENTS AND MAIN RESULTS: The mean platelet counts were similar between the groups during CPB. There was no significant difference in 24-hour mediastinal chest tube drainage (mean +/- standard deviation; median) between the heparin-coated (n = 44, 1096 +/- 401, 1015 mL) and uncoated group (n = 44, 1150 +/- 548, 1040 mL; p = 0.91). The heparin-coated group received less allogeneic packed red blood cells (0.9 +/- 1.6, 0.0 v 1.5 +/- 1.8, 1.0 U; p = 0.04). CONCLUSIONS: The use of a heparin-coated or uncoated cardiopulmonary bypass circuit and full heparinization marginally reduced only red blood cell transfusion but was not associated with platelet sparing or reduced perioperative bleeding.

Adult↗

PubMed2003

Patients with a history of type II heparin-induced thrombocytopenia with thrombosis requiring cardiac surgery with cardiopulmonary bypass: a prospective observational case series.

Heparin-induced thrombocytopenia with thrombosis (HITT) type II is a life-threatening complication of heparin therapy that most often occurs after 5-10 days of exposure to heparin. Anticoagulation is a significant concern for patients with HITT type II being prepared for cardiac surgery requiring cardiopulmonary bypass (CPB). We report a case series of 12 patients with a history HITT type II who underwent CPB and cardiac surgery. Six patients did not express the antibody that mediates HITT type II immediately before surgery. Heparin was used as the anticoagulant for the duration of CPB only, and all these patients did well without thrombotic complications. Six patients expressed the antibody that mediates HITT type II immediately before surgery. Hirudin was used as the anticoagulant for CPB in these patients. The ecarin clotting time was used to guide hirudin therapy during CPB. The patients receiving hirudin did well, but they had a large amount of bleeding, required transfusions of multiple allogeneic blood products, and had a frequent rate of reexploration of the mediastinum after CPB.

Adolescent↗

PubMed2002

A study of a weight-adjusted aprotinin dosing schedule during cardiac surgery.

UNLABELLED: Aprotinin is effective during cardiac surgery for reducing blood loss and transfusion requirements, but it is expensive. Aprotinin is usually administered to adults according to a fixed protocol regardless of the patient's weight. We previously developed a weight-based dosing protocol for aprotinin. The purpose of this prospective observational study was to determine aprotinin levels in four patient groups (n = 10 each) using the new weight-based aprotinin dosing schedule that should achieve concentrations over 100, 150, 200, and 250 kallikrein inhibitory units/mL compared with full-dose aprotinin regimen (n = 10) by a simple functional aprotinin assay. There was no difference in patient demographic or surgical variables among groups. There was less within patient variation in plasma aprotinin concentrations over time in the new weight-based aprotinin dosing schedule groups compared with the full-dose aprotinin regimen group (P < 0.02 for all comparisons). The mean plasma aprotinin concentration achieved with the new weight-based aprotinin dosing schedule was similar to the desired concentrations, but we were unable to reduce between-patient variability in aprotinin concentrations. IMPLICATIONS: The current dosing schedule for aprotinin results in a large variation in aprotinin plasma concentrations between patients and a large variation within each patient over time. A new weight-based dosing schedule reduced variation of aprotinin concentration over time, but was unable to reduce between-patient variability in aprotinin concentration.

Aged↗