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Biomedical subjects

S V Mallett

Publications and source records attributed to S V Mallett.

16 recordsLinked to original sources
PubMed2001

The effects of balanced versus saline-based hetastarch and crystalloid solutions on acid-base and electrolyte status and gastric mucosal perfusion in elderly surgical patients.

UNLABELLED: The IV administration of sodium chloride solutions may produce a metabolic acidosis and gastrointestinal dysfunction. We designed this trial to determine whether, in elderly surgical patients, crystalloid and colloid solutions with a more physiologically balanced electrolyte formulation, such as Hartmann's solution and Hextend, can provide a superior metabolic environment and improved indices of organ perfusion when compared with saline-based fluids. Forty-seven elderly patients undergoing major surgery were randomly allocated to one of two study groups. Patients in the Balanced Fluid group received an intraoperative fluid regimen that consisted of Hartmann's solution and 6% hetastarch in balanced electrolyte and glucose injection (Hextend). Patients in the Saline group were given 0.9% sodium chloride solution and 6% hetastarch in 0.9% sodium chloride solution (Hespan). Biochemical indices and acid-base balance were determined. Gastric tonometry was used as a reflection of splanchnic perfusion. Postoperative chloride levels demonstrated a larger increase in the Saline group than the Balanced Fluid group (9.8 vs 3.3 mmol/L, P = 0.0001). Postoperative standard base excess showed a larger decline in the Saline group than the Balanced Fluid group (-5.5 vs -0.9 mmol/L, P = 0.0001). Two-thirds of patients in the Saline group, but none in the Balanced Fluid group, developed postoperative hyperchloremic metabolic acidosis (P = 0.0001). Gastric tonometry indicated a larger increase in the CO2 gap during surgery in the Saline group compared with the Balanced Fluid group (1.7 vs 0.9 kPa, P = 0.0394). In this study, the use of balanced crystalloid and colloid solutions in elderly surgical patients prevented the development of hyperchloremic metabolic acidosis and resulted in improved gastric mucosal perfusion when compared with saline-based solutions. IMPLICATIONS: This prospective, randomized, blinded trial showed that, in elderly surgical patients, the use of balanced IV solutions can prevent the development of hyperchloremic metabolic acidosis and provide better gastric mucosal perfusion compared with saline-based fluids.

Acid-Base Equilibrium↗
PubMed2000

Reducing red blood cell transfusion in elective surgical patients: the role of audit and practice guidelines.

In 1996, we prospectively audited peri-operative transfusion practice in elective surgical patients over a 3-month period. Two-unit transfusions represented 60% of all transfusions. Haemoglobin was measured infrequently prior to transfusion and the main 'trigger' for transfusion was an estimated blood loss in excess of 500 ml. Transfusion guidelines that required the haemoglobin level to be measured immediately before transfusion were introduced. The audit was repeated in 1998; transfusion 'triggers' and the number of transfusions for the two periods were compared. In the second audit, the total number of transfusions decreased by 43%. The mean estimated blood loss associated with a 2-unit transfusion had increased from 608 (373) ml to 1320 (644) ml (p < 0.01) and the estimated haemoglobin concentration after transfusion had decreased from 12.4 (1.8) g.dl-1 to 9.9 (2.4) g.dl-1 (p < 0.01). These results suggest that transfusion guidelines can have a significant impact on clinical practice.

Attitude of Health Personnel↗
PubMed2000

Anticoagulant-induced pseudothrombocytopenia in a patient presenting for coronary artery bypass grafting.

A 73-yr-old man with severe ischaemic heart disease presented for coronary artery bypass grafting. His preoperative platelet count, obtained from an ethylene diamine tetraacetic acid (EDTA) sampling bottle, was 61 x 10(9) litre-1, but he had no history of bleeding problems. Previous platelet counts demonstrated results ranging from 16 x 10(9) litre-1 to 254 x 10(9) litre-1 with variable degrees of in vitro platelet clumping. Preoperative thrombelastography reflected a normal coagulation profile. The laboratory findings and the absence of a history of haemorrhagic complications suggested a diagnosis of EDTA-dependent pseudothrombocytopenia. We present the perioperative implications of this in vitro phenomenon and methods of detecting the functional and numerical integrity of circulating platelets.

Aged↗
PubMed1997

Use of heparinase modified thrombelastography in liver transplantation.

Severe coagulopathies can occur during liver transplantation, particularly after reperfusion of the grafted liver. Heparin release has been proposed as one of the factors contributing to this coagulopathy. We have analysed the thrombelastograph (TEG) traces of 55 patients after reperfusion using native and heparinase-treated samples. In almost all cases an abnormal native TEG was improved in vitro by heparinase, demonstrating the presence of heparin or a heparin-like substance. The heparinase-modified TEG allowed assessment of the underlying coagulation status, providing a rational guide to blood component replacement or treatment of fibrinolysis.

Blood Coagulation Disorders↗
PubMed1995

Thrombelastography reveals two causes of haemorrhage in HELLP syndrome.

We describe the use of thrombelastography in HELLP syndrome (Haemolysis, Elevated Liver Enzymes, Low Platelets). It differentiated between two possible causes of significant haemorrhage and revealed an accompanying underlying fibrinolysis. This allowed specific therapy to be directed at both abnormalities and, we believe, helped prevent this patient from undergoing radical surgery to curb blood loss.

Adult↗
PubMed1994

Hypomagnesaemia, cardiac arrhythmias and orthotopic liver transplantation.

Two patients who underwent orthotopic liver transplantation and developed peroperative cardiac arrhythmias are presented. In one, the arrhythmias were refractory to treatment with anti-arrhythmic drug therapy until serum magnesium levels were restored to normal. The other patient had a low pre-operative serum magnesium level and developed atrial fibrillation on induction of, and during, anaesthesia. Patients undergoing orthotopic liver transplantation may be a group especially predisposed to hypomagnesaemia. The importance of monitoring serum magnesium levels in such patients who develop peroperative cardiac arrhythmias is emphasised.

Atrial Fibrillation↗
PubMed1993

Pulmonary platelet aggregates: possible cause of sudden peroperative death in adults undergoing liver transplantation.

AIMS: To determine if massive pulmonary platelet thromboembolism is a common cause of peroperative death following liver transplantation; and to compare the incidence of this event with patients dying after non-transplantation procedures. METHODS: Necropsy tissues from all patients dying within 10 days of operation during the past three and a half years were studied (six liver transplantations and 13 unrelated operations). Haematoxylin and eosin stained sections of all tissues were examined. Additional sections of lung tissue were immunostained for constituents of thrombus (fibrin and platelets). RESULTS: At necropsy the lungs from all six liver transplant recipients were heavy with a rubbery texture and little oedema fluid. Those from non-transplantation patients appeared normal or very oedematous. Microscopic examination showed that there were numerous platelet aggregates occluding pulmonary capillaries in all six transplant recipients, but in only three of the non-transplant patients. These thrombi were numerous in patients dying during surgery and the number was underestimated in routine sections because of the surrounding capillary congestion. Detection was improved by immunostaining for platelets with factor XIIIA and platelet glyco-protein IIIa. CONCLUSIONS: Massive platelet thromboembolism is a likely cause of death in patients dying unexpectedly following recent liver transplantation. Non-transplantation patients dying during surgery who show similar appearances usually have conditions known to have a high risk of thrombosis or embolism (cement hypotension syndrome and disseminated intravascular coagulation). The cause of this extensive platelet activation in liver transplant recipients is uncertain and may be multifactorial. The unusual rubbery consistency of the lungs on macroscopic examination could alert the pathologist to the underlying condition. Immunostaining for platelets improves the detection microscopically.

Adult↗
PubMed1992

Thrombelastography.

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Blood Coagulation↗
PubMed1991

The intra-operative use of trasylol (aprotinin) in liver transplantation.

Aprotinin has been reported to reduce blood loss in difficult cases requiring cardiopulmonary bypass surgery and more recently in liver transplantation. Over a 9-month period we compared the effects of an intra-operative infusion of aprotinin on transfusion requirements and coagulation profiles in 12 patients undergoing liver transplantation for end-stage cirrhosis with an equal number of consecutive transplants in patients with similar pathology who did not receive aprotinin. Transfusion of blood and blood products was reduced to one-third in the aprotinin-treated group. Operative time was also significantly reduced, as was ICU stay post-operatively. Aprotinin profoundly inhibits fibrinolysis and this is likely to be the major effect by which blood loss is reduced. Thromboelastography revealed severe fibrinolytic changes in the anhepatic stage in 4 of 6 controlled patients; this accelerated in 3 following reperfusion of the new graft. By contrast, only 1 patient of 12 in the aprotinin-treated group showed fibrinolytic activity in the anhepatic period, and none showed evidence of fibrinolysis following reperfusion of the new graft.

Aprotinin↗
PubMed1987

Decreasing post-succinylcholine myalgia in outpatients.

The effectiveness of four pretreatment regimens in decreasing succinylcholine-induced myalgias was studied in healthy outpatients undergoing general anaesthesia for ambulatory surgery. Four hundred and forty adult females were randomly assigned to one of four pretreatment groups. Three hundred and ninety-five patients completed the study. One of the following pretreatments was given prior to injection of 1.5 mg X kg-1 of succinylcholine: normal saline IV three minutes and again immediately prior to succinylcholine; 0.06 mg X kg-1 d-tubo-curarine (dTc) IV three minutes prior and normal saline IV immediately prior; normal saline IV three minutes prior and 1.5 mg X kg-1 lidocaine IV immediately prior; 0.06 mg X kg-1 dTc IV three minutes prior and 1.5 mg X kg-1 lidocaine IV immediately prior. Fasciculations after injection of succinylcholine were observed and recorded. Patients were contacted by telephone 40-48 hours postoperatively and questioned about the presence of muscle pains. These pains, if present, were graded either mild or moderate to severe. The patients in the two dTc-containing groups exhibited less fasciculations than patients in the other two experimental groups. The dTc-lidocaine group had a lower incidence of moderate to severe fasciculations than in any of the other three groups. Patients in the dTc, lidocaine, and dTc-lidocaine experimental groups reported a higher incidence of absence of muscle pain and a lower incidence of moderate-severe pain than did patients in the saline group. The dTc-lidocaine group had more patients without myalgia and less patients with moderate to severe myalgias than any of the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗