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Biomedical subjects

G A Nuttall

Publications and source records attributed to G A Nuttall.

36 records · Page 2Linked to original sources
PubMed1998

Temperature and duration of cardiopulmonary bypass influence transfusion requirements.

STUDY OBJECTIVE: To determine the influence of temperature and duration of cardiopulmonary bypass (CPB) on blood loss and transfusion requirements. DESIGN: Retrospective chart review. SETTING: Tertiary care, academic medical institution. MEASUREMENTS AND MAIN RESULTS: The charts of 378 patients who had undergone primary elective coronary artery bypass graft surgery were studied. Systemic perfusion of CPB had been conducted between 20 degrees C and 37 degrees C in all patients. Patient demographic, temperature during CPB, duration of CPB, blood loss, and transfusion requirements were all recorded. Hypothermic CPB patients had minor increases in requirements for transfusion of red blood cells (RBC; p = 0.01), fresh frozen plasma (FFP; p = 0.01), platelets (PLT; p = 0.003), and total (allogeneic and autologous) blood products (p < 0.001). Multivariate analysis revealed that decreased temperature after adjusting for duration was predictive of allogeneic (RBC, FFP, PLT, and cryoprecipitate) and total (allogeneic and autologous) transfusion requirements. The duration of CPB correlated with decreased temperature (r = -0.455; p < 0.0001). After adjusting for temperature, duration was only predictive of total (allogeneic and autologous) transfusion requirements. CONCLUSIONS: The institution of warm CPB has many ramifications for clinical practice. The hypothermic induced platelet dysfunction and increased duration associated with cold CPB may contribute to the minor increases in transfusion requirements. However, temperature appears to be a weak factor, neither supporting nor refuting the use of warm or cold CPB.

Anesthesia↗
PubMed1998

Normothermic cardiopulmonary bypass increases heparin requirements necessary to maintain anticoagulation.

OBJECTIVE: With the practice of warm cardiopulmonary bypass (CPB) at our institution we have observed an apparent increase in heparin requirements. CPB temperature predictability affects pharmacokinetics and differences in drug metabolism can be expected. We hypothesized that heparin requirements would increase with increasing CPB temperature. METHODS: Following Institutional Review Board approval, we reviewed the charts of 354 patients undergoing primary coronary artery bypass graft surgery. We recorded patient demographic data, CPB duration, heparin requirements, and temperature during CPB. CPB was conducted between 24 degrees C and 37 degrees C. The Spearman's correlation coefficient, Pearson chi-square, and rank-sum tests were used for data analysis. RESULTS: Core temperature during CPB correlated with heparin requirements (r = 0.13, p < 0.02). However, CPB duration was shorter in warm patients than in cold patients (r = -0.455, p < 0.0001). Additional heparin requirements adjusted for duration of CPB (units/minute) were also significantly greater in the warm group (p = 0.018). CONCLUSIONS: Maintenance of adequate heparin anticoagulation during CPB is clinically important. Warm CPB patients required more heparin per minute than those undergoing cold CPB. More frequent assessment of anticoagulation and administration of additional heparin should be considered in patients undergoing warm CPB.

Aged↗
PubMed1998

A prospective randomized trial of the surgical blood order equation for ordering red cells for total hip arthroplasty patients.

BACKGROUND: The majority of crossmatched blood is for surgical patients, and most of it is never transfused. An alternative system for ordering red cell (RBC) units, called the surgical blood order equation (SBOE), which incorporates specific patient variables for surgical patients, has been developed. STUDY DESIGN AND METHODS: A prospective double-blind randomized trial compared the SBOE with the maximal surgical blood order schedule (MSBOS) system for ordering allogeneic RBC units in 60 patients undergoing total hip arthroplasty. Autologous RBCs were available for none of the patients. RESULTS: There were no differences in patient demographic, surgical, or laboratory variables at any time. The median number (range) of allogeneic RBC units ordered was 2 (2-3) for the MSBOS and 0 (0-3) for the SBOE (p<0.0001). The SBOE ordered the correct number of RBC units for 58 percent of patients, while the MSBOS did so for 7 percent (p<0.0001). The SBOE had a lower crossmatch-to-transfusion ratio than the MSBOS (0.83 vs. 4.12). Costs were also lower with the SBOE. CONCLUSION: Incorporation of patient factors in the use of the SBOE system resulted in increased efficiency of blood-ordering practices for total hip arthroplasty.

Adult↗
PubMed1998

The relation between the platelet-activated clotting test (HemoSTATUS) and blood loss after cardiopulmonary bypass.

BACKGROUND: Platelet dysfunction is one of several major causes of bleeding after cardiopulmonary bypass. A timely, simple, point-of-care determinant of platelet function recently became available for clinical use. Adding platelet-activating factor to conventional activated clotting time methods (platelet-activated clotting test [PACT]) produces rapid results (<15 min) and may yield a measure of platelet responsiveness and whole-blood procoagulant activity. METHODS: Blood samples were drawn from 100 patients after cardiac surgery on their arrival in the intensive care unit for PACT, platelet count, prothrombin time (PT), and activated partial thromboplastin time (aPTT). Cumulative blood loss at 4, 8, and 12 h after arrival in the intensive care unit and perioperative transfusion requirements were quantitated. Coagulation tests and mediastinal blood loss were compared using the Spearman rank test and Pearson correlation. The sensitivity and specificity of the laboratory tests for predicting blood loss were analyzed using the receiver operating characteristic method. RESULTS: The PT was the only test that correlated with blood loss at 4, 8, and 12 h. The PACT did not correlate with blood loss at 4, 8, or 12 h, nor did the PACT correlate with the PT or the aPTT. The sensitivity and specificity of the PACT were less than those of the PT in predicting blood loss. Only the PT correlated with platelet and fresh frozen plasma transfusion. CONCLUSIONS: The PT correlated with blood loss and transfusion requirements and was superior to PACT, aPTT, and platelet count for predicting excessive blood loss after cardiopulmonary bypass.

Aged↗
PubMed1998

No difference exists in the alteration of circadian rhythm between patients with and without intensive care unit psychosis.

OBJECTIVE: To determine if a difference exists in the circadian rhythm entrainment between patients with and without intensive care unit (ICU) psychosis. DESIGN: Retrospective chart reviews from 149 consecutive patients admitted to our ICU during the period of January 1993 to August 1993. Twelve patients with a history of mental illness or alcohol or substance abuse were excluded from the study. SETTING: A 20-bed surgical ICU at a large teaching hospital. PATIENTS: Patients who remained in the ICU for a minimum of 2 days after undergoing thoracic or vascular operations. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Hourly temperature and urine output were ascertained from the patient records. The time of temperature and urine output nadir was used as a marker of circadian rhythm. Of the 137 patients included in the study, 17 (12.4%) developed ICU psychosis as defined by standard criteria. The time of temperature nadir was randomly distributed around the clock for each group. Cosinar rhythmometry analysis of temperature data showed a lack of circadian rhythm entrainment in most patients up to the third postoperative day. No statistically significant difference exists in the deviation of such impairment between the groups. CONCLUSION: Either patients who develop ICU psychosis have an increased sensitivity to an alteration of their circadian rhythm, or ICU psychosis develops independent of circadian rhythm abnormalities.

Adaptation, Physiological↗
PubMed1997

Coagulation tests predict bleeding after cardiopulmonary bypass.

OBJECTIVE: To determine the accuracy of coagulation profile laboratory tests, thromboelastography, and Sonoclot (SCT) values for predicting microvascular bleeding after cardiopulmonary bypass (CPB). DESIGN: A prospective, blinded trial. SETTING: A large academic medical center. PARTICIPANTS: Eighty-two adult patients undergoing elective cardiac surgery. INTERVENTIONS: Ten minutes after CPB, thromboelastography, SCT, and coagulation profile tests (bleeding time, prothrombin time, activated partial thromboplastin time, fibrinogen, fibrin split products, platelet count, mean platelet volume, and platelet hematocrit) were determined from a whole blood sample taken from an existing arterial catheter. Patients were subjectively defined as "bleeders" or "non-bleeders" by blinded clinical observers. Preoperative baseline tests were also obtained. MEASUREMENTS AND MAIN RESULTS: Thirty of the 82 patients (36.6%) were characterized as bleeders. Coagulation profile tests had the best correlation with intraoperative and postoperative blood loss. The specificity, sensitivity, and negative and positive predictive values were determined by receiver operating characteristic analysis, and the test values that differentiated normal from abnormal (bleeding) patients were determined. The coagulation profile laboratory tests had the greatest maximal sensitivity and specificity for predicting bleeding. These predictive values were outside the normal range for these laboratory tests. The thromboelastography values that produced maximal sensitivity and specificity were in the normal range for that test. CONCLUSION: Contrary to previous studies, coagulation profile tests had the greatest sensitivity and specificity to differentiate patients with excessive bleeding (abnormal) from those without excessive bleeding (normal) after CPB. Therefore, these tests should be used to guide transfusion therapy in patients who have excessive bleeding after CPB.

Adult↗
PubMed1997

The incidence of artery puncture with central venous cannulation using a modified technique for detection and prevention of arterial cannulation.

BACKGROUND: Cannulation of the central circulation is essential for management of patients who require major surgery, and for patients who are critically ill. Arterial puncture is the most frequent complication associated with central venous cannulation, and is potentially fatal. Detection of arterial puncture can be problematic, especially in patients with cyanotic congenital heart disease. METHODS: One thousand eleven consecutive cardiothoracic and vascular surgical patients who required central venous cannulation were studied using a new technique for detection of arterial puncture and prevention of arterial cannulation. This technique involves continuous pressure transduction of the steel introducer needle. Central venous cannulation was attempted in all patients. The sites of attempted catheterizations, number of arterial punctures and cannulations, and the number of successful catheterizations were noted. All patients were treated in accordance with standard anesthetic and surgical techniques in the institution. RESULTS: One thousand one hundred seventy-two central venous catheters were placed. The overall success rate was 99.6%. The incidence of arterial puncture was 9.3% for central venous cannulation attempts of the internal jugular, subclavian, and femoral veins. No arterial cannulation occurred, and none of the patients had significant complications. Congenital heart disease patients had a higher incidence of arterial puncture (14.1%) and a lower rate (96.8%) of successful cannulation. CONCLUSION: Pressure transduction of the steel needle is a useful technique for detecting arterial puncture and preventing arterial cannulation during attempts to achieve central venous cannulation.

Adolescent↗
PubMed1997

Does the platelet-activated clotting test (HemoSTATUS) predict blood loss and platelet dysfunction associated with cardiopulmonary bypass?

Platelet dysfunction is a major cause of bleeding after cardiopulmonary bypass (CPB). No timely, simple, point-of-care determinant of platelet function is available for clinical use. Adding platelet-activating factor to conventional activated clotting time methods (platelet-activated clotting test [PACT]) (HemoSTATUS; Medtronic, Inc., Parker, CO) produces rapid results (<3 min) and may yield a measure of platelet responsiveness and whole blood procoagulant activity. Blood samples were drawn for PACT, platelet count, prothrombin time, activated partial thromboplastin time, and thromboelastogram (TEG) from 200 patients undergoing cardiac surgery. The PACT significantly decreased from the baseline to postprotamine time interval (P < 0.001). The PACT correlated with 4-h mediastinal blood loss (r = -0.30, P = 0.014). The TEG maximum amplitude also correlated with 4-h mediastinal blood loss (r = -0.32, P = 0.003). The PACT had a sensitivity and specificity comparable to routine laboratory coagulation tests in predicting blood loss. The TEG maximum amplitude, however, was more predictive than both the PACT and routine coagulation tests in this respect. The PACT may be a useful indicator of platelet responsiveness or whole blood procoagulant activity, but we did not find it superior to other tests of coagulation function for predicting excessive blood loss after CPB.

Adult↗
PubMed1996

The predictors of red cell transfusions in total hip arthroplasties.

BACKGROUND: Most blood crossmatched in a hospital blood bank is for surgical patients, and the majority is never transfused. The maximal standard blood order schedule is used to promote efficient ordering practices for surgical patients. STUDY DESIGN AND METHODS: To ascertain the predictors of red cell transfusions for patients undergoing total hip arthroplasty, the charts of 299 adult patients undergoing primary and revision total hip arthroplasty were reviewed. A surgical blood order equation was developed for calculating the number of units of red cells that should be ordered. Stepwise regression analysis was used to determine which patient-and-case-related variables should be considered in the surgical blood order equation. RESULTS: The significant indicators for allogeneic red cell transfusion to patients on the day of total hip arthroplasty were preoperative hemoglobin concentration, weight, age, estimated blood loss, and aspirin use. The surgical blood order equation would result in a lower crossmatch-to-transfusion ratio than would the maximal standard blood order schedule (1.23 vs. 3.14). Costs were also lower with the surgical blood order equation. CONCLUSION: Incorporation of patient factors resulted in increased efficiency of blood-ordering practices in total hip arthroplasty.

Adult↗
PubMed1996

The relationship between cerebral blood flow and transcranial Doppler blood flow velocity during hypothermic cardiopulmonary bypass in adults.

A noninvasive, simple, and continuous method to assess cerebral perfusion during cardiopulmonary bypass (CPB) could help prevent cerebral ischemia. Transcranial Doppler sonography (TCD) allows a noninvasive, on-line measurement of blood flow velocity in cerebral arteries. The correlation of TCD-estimated and actual cerebral blood flow (CBF) has not been well studied during CPB. We determined the correlation of middle cerebral artery (MCA) mean velocity and CBF determined by the Kety-Schmidt method during nonbypass and two hypothermic bypass flow conditions. Sixteen patients undergoing hypothermic (27 degrees C) CPB for coronary artery bypass grafting and/or valve replacement surgery were enrolled in the study. We were able to determine MCA velocity in only 12 patients. We determined CBF and MCA velocity in each patient during four 15-min study periods: 1) prebypass after sternotomy before aortic cannulation; 2) hypothermic (27 degrees C) CPB with 1.2 L.min-1.m-2 pump flow; 3) hypothermic CPB with 2.4 L.min-1.m-2 pump flow, and 4) 30 min after weaning from CPB. There was no difference in the mean arterial pressure between the two CPB pump blood flows. The pooled change in MCA velocity and CBF as percentage of baseline (prebypass) for all patients and at all time points had a correlation of 0.33 (r). A decrease or increase in MCA velocity did not necessarily indicate a corresponding decrease or increase in CBF. This technology may be of limited usefulness during the circulatory condition of hypothermic, nonpulsatile CPB.

Aged↗
PubMed1995

Determination of normal versus abnormal activated partial thromboplastin time and prothrombin time after cardiopulmonary bypass.

OBJECTIVE: The study's objective was to determine the prothrombin time (PT) and activated partial thromboplastin time (aPTT) values that differentiated normal from excessively bleeding patients immediately after cardiopulmonary bypass (CPB). DESIGN: A prospective blinded study. SETTING: A large academic medical center. PARTICIPANTS: 148 patients were studied. INTERVENTIONS: aPTT and PT were determined by the hospital laboratory and the Biotrack 512 Coagulation Monitor (Ciba Corning Diagnostics, Medfield, MA) from an arterial whole blood sample obtained 10 minutes after protamine administration. Patients were subjectively and objectively defined as "bleeders" or "nonbleeders" with blinded observers. MEASUREMENTS AND MAIN RESULTS: The specificity and sensitivity were determined by a receiver operating characteristic (ROC) analysis. Twenty-three of 148 patients (14.9%) were characterized as bleeders. The laboratory PT had a maximal specificity and sensitivity of 78% and 75%, respectively, at a value of 15.4 s, with a negative and positive predictive value of 93% and 33%, respectively. The maximal specificity and sensitivity of the laboratory aPTT was 64% and 76%, respectively, at a value of 46 s, with a negative and positive predictive value of 89% and 33%, respectively. aPTT and PT approached normal values after 12 hours in the intensive care unit. CONCLUSION: The aPTT and PT values that produce the maximal sensitivity and specificity in the ROC analysis may be helpful to differentiate patients who are bleeding excessively from those patients who are not after CPB and to guide transfusion of blood products. New whole blood coagulation devices with rapid turn-around times had similar predictive value for bleeding tendency compared with standardized laboratory tests.

Adult↗
PubMed1993

Intraoperative measurement of activated partial thromboplastin time and prothrombin time by a portable laser photometer in patients following cardiopulmonary bypass.

Intraoperative capabilities to rapidly assess coagulation status following cardiopulmonary bypass (CPB) may be of benefit in providing optimal hemostasis and transfusion management, because CPB causes abnormalities in coagulation that may increase morbidity and mortality. The Ciba Corning 512 coagulation monitor (Ciba Corning, Medfield, MA) is a compact and portable device that rapidly determines the prothrombin time (PT) and activated partial thromboplastin time (APTT) in whole blood samples. One hundred patients requiring CPB had APTT and PT determined in whole blood specimens by the 512 coagulation monitor and in plasma specimens by the hospital laboratory from the same arterial blood sample obtained after protamine administration. Correlation coefficients of 0.95 and 0.77 were obtained for the paired APTT and PT tests, respectively (P < 0.01). A bias of 12.6 seconds and 0.77 seconds was determined for the APTT and PT, respectively. The 95% confidence intervals of the bias of the APTT and PT were 9.7 seconds to 15.5 seconds and 0.3 seconds to 1.16 seconds, respectively. The 512 coagulation monitor provided APTT and PT results in less than 3 minutes compared to approximately 45 minutes for the hospital laboratory. A reduction in accuracy was associated with the 512 coagulation monitor PT and APTT when different sampling sites were used. The 512 coagulation monitor accuracy was not affected by a variation of hemoglobin concentration or platelet count between 6 and 12 gm/dL and 15 to 300 x 10(9)/L, respectively. In conclusion, the 512 coagulation monitor provided a rapid APTT and PT result, but the APTT was less accurate. Speeding access to hospital laboratory results would be even more efficacious and accurate.

Adult↗
PubMed1993

Establishing intravenous access: a study of local anesthetic efficacy.

We performed a double-blind, randomized, prospective study to determine the local anesthetic that provided the best analgesia for insertion of an 18-gauge intravenous (i.v.) catheter and to determine whether alkalinization of lidocaine decreases the pain of intradermal injection. There were 280 healthy adult patients assigned randomly to seven different groups: benzyl alcohol 0.9% in normal saline, 2-chloroprocaine 3%, lidocaine 1%, lidocaine 1% with preservative, alkalinized lidocaine 1% with preservative, normal saline, and a control group that received i.v. catheter placement without previous drug injection. A 10-cm visual analog pain scale (VAPS) was used to obtain pain scores after pre-i.v. drug injection and after iv catheter insertion. Benzyl alcohol in normal saline (0.61 +/- 0.11) and alkalinized lidocaine (0.69 +/- 0.10) had the lowest mean pain scores for drug injection and these were significantly different from other drugs (P < 0.05). Alkalinized lidocaine (0.7 +/- 0.18) had the lowest mean pain score for i.v. catheter insertion with nothing (no previous drug injected) (3.47 +/- 0.38) and normal saline (3.97 +/- 0.18) had the highest mean pain scores (P < 0.05). We conclude that alkalinized lidocaine decreased the pain associated with its injection. Alkalinized lidocaine was the best local anesthetic for i.v. catheter placement. Benzyl alcohol in normal saline was also effective.

Adult↗
PubMed1991

Protamine-heparin-induced pulmonary hypertension in pigs: effects of treatment with a thromboxane receptor antagonist on hemodynamics and coagulation.

Adverse hemodynamic reactions after protamine neutralization of heparin are an infrequent but important clinical problem. Pre-treatment of swine with a thromboxane A2 receptor antagonist has been reported to prevent the pulmonary hypertensive response occasionally seen after protamine reversal of heparin anticoagulation. In the current study, a control group of pigs (n = 9) received intravenous heparin (300 IU/kg), followed after 10 min by a neutralizing dose of protamine (3 mg/kg). A treatment group of pigs (n = 11) was treated identically, except that the thromboxane A2 receptor antagonist L-670596 (2 mg/kg) was infused intravenously 2 min after the protamine infusion. Hemodynamic and coagulation profiles were monitored during these procedures. Pulmonary hypertension developed and reached a peak within 2 min of protamine administration, often at the same time that L-670596 was administered in the treatment group. There was no statistical difference between control and treatment groups' peak pulmonary arterial pressure and peak pulmonary vascular resistance. However, the interval for return of mean pulmonary artery pressure from peak to baseline values was 11.6 +/- 3.1 versus 5.5 +/- 1.9 min (mean +/- SD) for control and treatment groups, respectively (P less than 0.01). Thromboxane B2 plasma concentrations increased in both groups and were correlated with the pulmonary hypertensive response (r = 0.86, P less than 0.01). Platelet aggregation to collagen was inhibited by the thromboxane A2 receptor antagonist (P less than 0.05). Bleeding time was prolonged beyond normal range in 50% of L-670596-treated pigs. All other coagulation tests in both groups returned to baseline after reversal of heparin with protamine and were unaffected by L-670596.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Transforming growth factor type beta can act as a potent competence factor for AKR-2B cells.

Transforming growth factor type beta (TGF beta) is a pleiotropic regulator of cell growth with specific high-affinity cell-surface receptors on a large number of cells; its mechanism of action, however, is poorly defined. In this report, we utilized the mouse fibroblast line AKR-2B to explore the question of the temporal requirements during the cell cycle in regard to both the growth inhibitory and the growth stimulatory action of TGF beta. The results indicate that AKR-2B cells are most sensitive to the inhibitory action of TGF beta during early to mid-G1. In addition, TGF beta need be present only briefly (as little as 1 min) in order to exert its inhibitory effect on EGF-induced DNA synthesis. Likewise, the stimulatory effect of TGF beta in the absence of EGF requires only an equally brief exposure to TGF beta. Use of homogeneous 125I-labeled TGF beta in a cell-binding assay demonstrates that TGF beta bound to cell-surface receptors can readily exchange into the culture medium T1/2 = 120 min), helping to rule out the possibility that persistent receptor-bound TGF beta is the source of a continuous stimulus. The data indicate that TGF beta exposure induces a stable state in the cell (T1/2 = 20 h) similar to but distinct from the state of "competence" induced by platelet-derived growth factor (PDGF).

Animals↗
PubMed1984

Metabolic effects of oral fructose in the liver of fasted rats.

Twenty-four-hour-fasted rats were given fructose (4 g/kg) by gavage. Fructose absorption and the portal vein, aorta, and hepatic vein plasma fructose, glucose, lactate, and insulin concentrations as well as liver fructose and fructose 1-P, glucose, glucose 6-P, UDPglucose, lactate, pyruvate, ATP, ADP, AMP, inorganic phosphate (Pi), cAMP, and Mg2+, and glycogen synthase I and phosphorylase alpha were measured at 10, 20, 30, 40, 60 and 120 min after gavage. Liver and muscle glycogen and serum uric acid and triglycerides also were measured. Fifty-nine percent of the fructose was absorbed in 2 h. There were modest increases in plasma and hepatic fructose, glucose, and lactate and in plasma insulin. Concentrations in the portal vein, aorta, and hepatic vein plasma indicate rapid removal of fructose and lactate by the liver and a modest increase in production of glucose. The source of the increase in plasma lactate is uncertain. Hepatic glucose 6-P increased twofold; UDPglucose rose transiently and then decreased below the control level. Fructose 1-P increased linearly to a concentration of 3.3 mumol/g wet wt by 120 min. There was no change in ATP, ADP, AMP, cAMP, Pi, or Mg2+. Serum triglycerides and uric acid were unchanged. Glycogen synthase was activated by 20 min without a change in phosphorylase alpha. This occurred with a fructose dose that did not significantly increase either the liver glucose or fructose concentrations. Liver glycogen increased linearly after 20 min, and glycogen storage was equal in liver (38.4%) and muscle (36.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗