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Biomedical subjects

C W Whitten

Publications and source records attributed to C W Whitten.

48 records · Page 3Linked to original sources
PubMed1990

Fluid therapy and the resuscitation of traumatic shock.

Fluid management of the traumatized patient begins with assessment of volume status via palpation of pulses; evaluation of mental status; and measurement of urine output, arterial blood pressure, and central pressures. Intravascular line placement and choice of initial resuscitation fluids should be individualized to the clinical situation, although in most situations a crystalloid solution continues to be the initial fluid of choice. Following initial stabilization, the intravenous fluid administered can be tailored to a given situation, chosen only after the deranged fluid balance is sequentially classified according to alterations of volume, concentration, and composition. Parenteral fluids may be divided into two groups: crystalloids and colloids. The indications, complications, and controversies surrounding various resuscitation modalities have been reviewed.

Colloids↗
PubMed1989

Desmopressin acetate following cardiopulmonary bypass: evaluation of coagulation parameters.

Desmopressin acetate (DDAVP) has been advocated as efficacious in reducing mediastinal bleeding following cardiopulmonary bypass (CPB), and has been shown to ameliorate platelet dysfunction; however, this has not been evaluated during routine coronary artery bypass grafting (CABG). In the present study, this therapy was evaluated utilizing the thromboelastograph (TEG), a rapid, on-line means of diagnosing a coagulopathy. During elective CABG, 20 patients received either DDAVP, 0.3 microgram/kg, intravenously, following heparin reversal after CPB, or a placebo infusion, in a randomized, double-blind fashion. Hemostasis was monitored with both the TEG and conventional coagulation tests. No significant differences between the two groups were found at induction, postprotamine, post-"study infusion," or 2 hours postoperatively, with the exception of the postoperative PTT (31.1 +/- 3.2 v 36.5 +/- 5.9 seconds for DDAVP v placebo, P = 0.03). Total blood products transfused intraoperatively, and in the first 8, 16, 24, or 48 postoperative hours, were also similar between the groups. No manifestations of hypercoagulability were seen, but hypotension during the infusion was noted in four patients receiving DDAVP, and in none of the controls. It is concluded that the expense and potential complications of DDAVP therapy do not justify its routine use in CABG.

Blood Coagulation↗
PubMed1989

Considerations for anesthetic management during veno-venous bypass in adult hepatic transplantation.

Intraoperative data from 42 adult orthotopic hepatic transplant recipients were analyzed retrospectively to assess the hemodynamic, coagulation, and thermal effects of heparinless veno-venous bypass using a constrained vortex pump. Transient hemodynamic changes occurring at the onset of bypass included decreases in temperature (-10.7%), heart rate (-18.7%) and arterial pressure (-15.1%); and increases in central venous pressure (27.6%) and ECG T wave amplitude (231.6%). Abrupt decreases in cardiac output and pump flow occurred with termination of the portal limb of bypass, which is required to allow completion of the portal vein anastomosis. However, significant continuous decreases were observed in bypass flow and cardiac output during the entire bypass period. The blood volume became concentrated as indicated by increases in hematocrit, colloid osmotic pressure, serum osmolality and serum sodium. Changes in colloid osmotic pressure were inversely related to bypass flow. These data, along with an accumulating base deficit, suggest that veno-venous bypass is associated with less than optimal perfusion of the abdomen and lower extremities. Flow dependent third space fluid accumulation is most likely responsible for decreasing cardiac output and pump flow during the bypass period. No clinically significant coagulopathy could be attributed to the use of veno-venous bypass. There were no significant changes in platelet counts, fibrinogen levels or prothrombin times. The activated partial thromboplastin time decreased from 60.5 to 50.2 seconds. Patient core temperature decreased three times more rapidly (0.9 degrees C/hr) during bypass than at any other time during the procedure.

Adult↗
PubMedDate not supplied

Effects of three anesthetic induction techniques on heart rate variability.

STUDY OBJECTIVE: To investigate the effects of different clinical induction techniques on heart rate variability (HRV). DESIGN: Two studies are reported. Study 1 prospectively compared the effects of two induction techniques (etomidate vs. thiopental sodium) known to have widely disparate effects on cardiovascular reflexes. Study 2 specifically investigated whether the vagotonic effects of sufentanil cause an increase in vagally mediated HRV. SETTING: Elective surgery in a university-affiliated hospital. PATIENTS: Study 1: 18 ASA physical status I patients having minor surgery; Study 2: 10 ASA physical status III and IV patients having cardiac surgery. INTERVENTIONS: In Study 1, anesthesia was induced with either etomidate 0.3 mg/kg or thiopental sodium 4 mg/kg with 60% nitrous oxide in oxygen. In Study 2, anesthesia was induced with a sufentanil infusion (total dose 2.9 +/- 0.2 micrograms/kg). MEASUREMENTS AND MAIN RESULTS: The electrocardiogram-derived heart rate signal was subjected to power spectral analysis (similar to electroencephalographic analysis) to obtain measurements of (1) absolute HRV power [units of (beats per minute)2] within defined frequency ranges (HRVLO = power between 0 and 0.125 Hz; HRVHI = power between 0.126 and 0.5 Hz; HRVTOT = HRVLO + HRVHI) and (2) normalized HRV power (the percentage of total power) within these same frequency ranges [e.g., %HRVHI = (HRVHI/HRVTOT) x 100%]. In Study 1, both techniques caused large reductions in HRVTOT. The reduction caused by the thiopental sodium technique (-89% +/- 2%) significantly exceeded that caused by the etomidate technique (-58% +/- 13%, p less than 0.02). In Study 2, sufentanil decreased absolute power measurements of vagally mediated HRV (-69 +/- 12 change in HRVHI) but increased corresponding normalized measurements of vagally mediated HRV (90% +/- 30% increase in %HRVHI). CONCLUSIONS: In Study 1, the greater reduction in HRV with the thiopental sodium technique provides evidence that the depressant effects of anesthetics on HRV are related in part to their effects on cardiovascular reflexes. However, the significant depression in HRV caused by the etomidate technique suggests that mechanisms other than baroreflex depression (e.g., impaired consciousness) also are important in these depressant effects. In Study 2, the decrease in HRVHI caused by sufentanil documents that absolute power measurements of vagally mediated HRV are not correlated with changes in parasympathetic tone during a potent opioid induction. This lack of a correlation may result from the decrease in total HRV observed with loss of consciousness. The increase in %HRVHI suggests that normalized measurements of HRV may still provide an index of changes in sympathetic-parasympathetic balance, even when total HRV is decreased following anesthetic administration.

Adolescent↗
PubMedDate not supplied

Influence of ketorolac tromethamine on clot elastic strength in humans as assessed by thromboelastography.

STUDY OBJECTIVE: To evaluate the effect of ketorolac tromethamine on coagulation using thromboelastography (TEG). DESIGN: TEGs were performed in each patient before and after ketorolac administration. Each patient's predrug results were used as control measurements for comparison with the postdrug results. SETTING: Medical center surgical unit. PATIENTS: Twenty ASA physical status I and II patients undergoing minor elective surgery; 12 healthy volunteers. INTERVENTIONS: TEGs were performed in all subjects before and 60 minutes after the intramuscular (IM) administration of ketorolac tromethamine 60 mg. Ten surgical patients were studied in the intraoperative period, and 10 surgical patients were studied in the postoperative period. The 12 healthy volunteers did not undergo a surgical procedure. MEASUREMENTS AND MAIN RESULTS: Specific parameters assessed from the TEGs were reaction time (R time), coagulation time (RK time), clot formation rate (angle of deflection), and maximum clot strength (maximum amplitude of deflection). Ketorolac administration did not cause statistically significant changes in these parameters in any of the three groups studied. CONCLUSIONS: IM administration of ketorolac tromethamine 60 mg did not significantly alter the speed of formation or viscoelastic strength of clots as measured by TEG. These results provide additional support for prior clinical studies confirming the safety of ketorolac administration in the perioperative period.

Adult↗
PubMedDate not supplied

Administration of high-dose aprotinin during nonprimary cardiovascular surgery: case reports and review of the literature.

The perioperative management of two patients undergoing complex "redo" cardiac surgical procedures are presented. The management of both patients included the prophylactic administration of aprotinin via a "compassionate use" protocol. Aprotinin, a serine protease inhibitor, has been shown to limit the exposure to blood and blood products in patients undergoing high-risk cardiac surgical procedures. In late December 1993, the Food and Drug Administration approved aprotinin for administration to cardiac surgical patients considered at high risk for post-cardiopulmonary bypass coagulopathies. Indications for the administration of aprotinin, as well as a brief review of the literature relating to the perioperative administration of aprotinin, are included.

Adult↗