[Management of direct oral anticoagulants for invasive procedures]

Three new Direct Oral Anticoagulants (DOACs), rivaroxaban, apixaban and dabigatran etexilate are available on the French market. Management of DOAC-induced bleeding risk remains challenging. For elective procedures with high hemorrhagic risk, a last DOAC intake five days before procedure ensures complete elimination in all patients. Heparin bridging therapy should be proposed only to patients at high thrombotic risk. For elective procedures with low hemorrhagic risk, the DOAC intake of the night before procedure should be omitted. For urgent procedures with high bleeding risk, DOAC plasmatic concentration can be helpful: concentration lower than 30 ng/mL should enable performing the procedure; a high concentration is associated with a higher bleeding risk, especially if higher than 400 ng/mL. In case of massive bleeding, no antidote is approved yet; activated prothrombin concentrates or non-activated 4-factors prothrombin concentrates could be considered.

Comparison of fondaparinux with low molecular weight heparin for venous thromboembolism prevention in patients requiring rigid or semi-rigid immobilization for isolated non-surgical below-knee injury

BACKGROUND

In several small studies, anticoagulant therapy reduced the incidence of venous thromboembolism (VTE) in patients with isolated lower-limb injuries.

OBJECTIVES

To compare the efficacy and safety of fondaparinux 2.5 mg (1.5 mg in patients with a creatinine clearance between 30 and 50 mL min(-1) ) over nadroparin 2850 anti-factor Xa IU.

PATIENTS AND METHODS

In this international, multicenter, randomized, open-label study, patients with an isolated non-surgical unilateral below-knee injury having at least one additional major risk factor for VTE and requiring, in the Investigator's opinion, rigid or semi-rigid immobilization for 21-45 days with thromboprophylaxis up to complete mobilization received subcutaneously once-daily either fondaparinux or nadroparin. The primary efficacy outcome was the composite of VTE (symptomatic or ultrasonographically detected asymptomatic deep vein thrombosis of the lower limb or symptomatic pulmonary embolism) and death up to complete mobilization. The main safety outcome was major bleeding.

RESULTS

We randomized 1349 patients (mean age 46 years): 88.7% had a bone fracture, and 83.8% had a plaster cast fitted (mean duration of immobilization, 34 days). The primary efficacy outcome occurred in 15 of 584 patients (2.6%) in the fondaparinux group and 48 of 586 patients (8.2%) in the nadroparin group (odds ratio, 0.30; 95% confidence interval [CI], 0.15-0.54; P < 0.001). A single major bleed was experienced by fondaparinux-treated patients and none by nadroparin-treated patients. These results were maintained up to the end of follow-up.

CONCLUSIONS

Fondaparinux 2.5 mg day(-1) may be a valuable therapeutic option over nadroparin 2850 anti-FXa IU day(-1) for preventing VTE after below-knee injury requiring prolonged immobilization in patients with additional risk factors.

[Dabigatran (Pradaxa): efficacy and safety]

There is considerable interest in developing new, orally available anticoagulants for the prevention and treatment of thrombotic disorders. In Europe, the low-molecular-weight heparins (LMWHs) are more commonly prescribed for thrombosis prevention, but require parenteral administration, platelets monitoring twice a week during the first month. Furthermore, LMWH are not synthetic. All of these characteristics can be an obstacle to optimal patient care, particularly when outpatient dosing is required after early discharge. New oral anticoagulants that require no monitoring and can be administered in a fixed dose without drug-drug and drug-food interactions would clearly offer practical advantages if shown to be safe and effective. dabigatran étexilate, a new oral, direct thrombin inhibitor, is the prodrug of the active compound dabigatran, which binds reversibly to thrombin with high affinity and specificity. This agent has a rapid onset of action, a predictable and reproducible that permit once-daily dosing. To date, more than 8,000 patients have been studied in clinical trials, and more than 38,000 individuals are enrolled in ongoing trials. Three major prospective, randomized, double-blind non-inferiority trials have compared the efficacy and safety of dabigatran étexilate (150 mg or 220 mg once-daily) starting postoperatively, with subcutaneous enoxaparin, in patients undergoing hip (RE-NOVATE trial) or knee arthroplasty (RE-MOBILIZE and RE-MODEL). Based on these trial results, dabigatran étexilate is approved for use in the European Union and Canada for primary prevention of VTE in patients having undergone elective total hip and knee arthroplasty. Pradaxa is now on the market in France since December 2008.

Adherence to a new oral anticoagulant treatment prescription: dabigatran etexilate

The recent development of new oral anticoagulants, of which dabigatran etexilate is currently at the most advanced stage of development, is the greatest advance in the provision of convenient anticoagulation therapy for many years. A new oral anticoagulation treatment, dabigatran etexilate, is already on the market in Europe. The main interest probably will be to improve the prescription and the adherence to an effective thromboprophylaxis in medical conditions such as atrial fibrillation without bleeding side effects, without the need for monitoring coagulation, and without drug and food interactions such as vitamin K anticoagulant (VKA) treatment. Dabigatran is particularly interesting for extended thromboprophylaxis after major orthopedic surgery in order to avoid daily injection for a month. However, oral long-term treatments such as VKA are not systematically associated with a higher compliance level than injected treatments such as low-molecular-weight heparins. Indeed, adherence to an oral treatment, instead of the usual daily injection in major orthopedic surgery, is complex, and based not only on the frequency of dosing but also on patient motivation, understanding, and socio-economic status. New oral anticoagulants may be useful in this way but education and detection of risk factors of nonadherence to treatment are still essential.

Oral dabigatran etexilate vs. subcutaneous enoxaparin for the prevention of venous thromboembolism after total knee replacement: the RE-MODEL randomized trial

BACKGROUND

Oral anticoagulants, such as dabigatran etexilate, an oral, direct thrombin inhibitor, that do not require monitoring or dose adjustment offer potential for prophylaxis against venous thromboembolism (VTE) after total knee replacement surgery.

METHODS

In this randomized, double-blind study, 2076 patients undergoing total knee replacement received dabigatran etexilate, 150 mg or 220 mg once-daily, starting with a half-dose 1-4 hours after surgery, or subcutaneous enoxaparin 40 mg once-daily, starting the evening before surgery, for 6-10 days. Patients were followed-up for 3 months. The primary efficacy outcome was a composite of total VTE (venographic or symptomatic) and mortality during treatment, and the primary safety outcome was the incidence of bleeding events.

RESULTS

The primary efficacy outcome occurred in 37.7% (193 of 512) of the enoxaparin group versus 36.4% (183 of 503) of the dabigatran etexilate 220 mg group (absolute difference, -1.3%; 95% CI, -7.3 to 4.6) and 40.5% (213 of 526) of the 150 mg group (2.8%; 95% CI, -3.1 to 8.7). Both doses were noninferior to enoxaparin based on the pre-specified noninferiority criterion. The incidence of major bleeding did not differ significantly between the three groups (1.3% versus 1.5% and 1.3% respectively). No significant differences in the incidences of liver enzyme elevation and acute coronary events were observed during treatment or follow-up.

CONCLUSIONS

Dabigatran etexilate (220 mg or 150 mg) was at least as effective and with a similar safety profile as enoxaparin for prevention of VTE after total knee-replacement surgery.

Oral dabigatran etexilate vs. subcutaneous enoxaparin for the prevention of venous thromboembolism after total knee replacement: the RE-MODEL randomized trial

BACKGROUND

Oral anticoagulants, such as dabigatran etexilate, an oral, direct thrombin inhibitor, that do not require monitoring or dose adjustment offer potential for prophylaxis against venous thromboembolism (VTE) after total knee replacement surgery.

METHODS

In this randomized, double-blind study, 2076 patients undergoing total knee replacement received dabigatran etexilate, 150 mg or 220 mg once-daily, starting with a half-dose 1-4 hours after surgery, or subcutaneous enoxaparin 40 mg once-daily, starting the evening before surgery, for 6-10 days. Patients were followed-up for 3 months. The primary efficacy outcome was a composite of total VTE (venographic or symptomatic) and mortality during treatment, and the primary safety outcome was the incidence of bleeding events.

RESULTS

The primary efficacy outcome occurred in 37.7% (193 of 512) of the enoxaparin group versus 36.4% (183 of 503) of the dabigatran etexilate 220 mg group (absolute difference, -1.3%; 95% CI, -7.3 to 4.6) and 40.5% (213 of 526) of the 150 mg group (2.8%; 95% CI, -3.1 to 8.7). Both doses were noninferior to enoxaparin based on the pre-specified noninferiority criterion. The incidence of major bleeding did not differ significantly between the three groups (1.3% versus 1.5% and 1.3% respectively). No significant differences in the incidences of liver enzyme elevation and acute coronary events were observed during treatment or follow-up.

CONCLUSIONS

Dabigatran etexilate (220 mg or 150 mg) was at least as effective and with a similar safety profile as enoxaparin for prevention of VTE after total knee-replacement surgery.

Venous thromboembolism and mortality after hip fracture surgery: the ESCORTE study

BACKGROUND

Recent changes in the management of hip fracture surgery patients may have modified the epidemiology of postoperative complications.

OBJECTIVES

We performed an observational study of a cohort of patients undergoing hip fracture surgery to update the epidemiological data on this population. The primary study outcome was the incidence of confirmed symptomatic venous thromboembolism (VTE) [defined as deep vein thrombosis, pulmonary embolism (PE), or both] at 3 months. Overall mortality at 1, 3 and 6 months was also evaluated.

PATIENTS/METHODS

Consecutive patients aged at least 18 years hospitalized in French public or private hospitals (531 centers) undergoing hip fracture surgery were recruited prospectively during 2 months in 2002 and a follow-up at 6 months. Predictive factors for VTE at 3 months and for death at 6 months were also analyzed.

RESULTS

Data from 6860 (97.3%) of the 7019 recruited patients were included in the analysis. The median age was 82 years. Low molecular weight heparins were administered perioperatively in 97.6% of patients; 69.5% received this treatment for at least 4 weeks. The actuarial rate of confirmed symptomatic VTE at 3 months was 1.34% (85 events, 95% CI: 1.04-1.64). There were 16 PEs (actuarial rate: 0.25%), three of which were fatal. Overall, 1006 (14.7%) patients were dead at 6 months. Cardiovascular disease was the most frequent cause of death (270 patients; 26.8%).

CONCLUSIONS

The current rate of postoperative VTE is low, but overall mortality remains high. Indeed, hip fracture patients belong to a vulnerable group of old people with comorbid diseases and a high risk of postoperative morbidity and mortality. An interdisciplinary approach could be the challenge to improve short and long-term outcome.

Comparaison célécoxib versus kétoprofène pour la prévention des ossifications péri-prothétiques de hanche

PURPOSE OF THE STUDY

Peri-prosthetic ossifications are a frequent complication of total hip arthroplasty, which, if effective preventive measures are not taken, occur in 60% of patients. Numerous classic antiinflammatory agents have shown their preventive efficacy. New selective Cox-2 inhibitors offer the possibility of reducing the adverse effects of antiinflammatory drugs but remain to be proven effective in this indication. The purpose of this pilot study was to compare the efficacy of celecoxib versus ketoprofen.

MATERIAL AND METHODS

In order to obtain sufficient statistical power to have a 70% chance of detecting a 25% difference between the two treatments with a 5% risk of error, we evaluated the incidence of peri-prosthetic ossifications of the hip in a prospective monocentric series of 52 patients receiving 400 mg celecoxib a day during a week. It was compared with the incidence in a control series of 52 matched patients (same age, gender, diagnosis, operator experience) given 200 mg ketoprofen iv for 48 hr then 300 mg po for 5 days as preventive treatment. Ossifications were studied on the plain AP view of the pelvis at a mean follow-up of more than 11 months (11.4 vs 11.9). The Brooker classification was determined.

RESULTS

The percent of patients presenting peri-prosthetic ossifications was equivalent. For the celecoxib group, 60% of the patients were free of ossifications; 28.9% presented stage 1 ossification and 11.1% stage 2 ossification; none of the hip exhibited a higher stage. In the ketoprofen control group, 53.2% of patients were free of ossification, 38.2% had stage 1 ossification, 6.4% stage 2, and 2.1% stage 3; there was no patient with stage 4. Fisher's exact test did not demonstrate a significant difference between the groups (p<0.51). Compared with an older series of patients who were not given preventive treatment, there was a significant reduction in incidence of peri-prosthetic ossification (p=0.014).

DISCUSSION

The two study groups were not significantly different for age, gender, or underlying disease. There were an equivalent number of cases of intolerance to treatment in the two groups.

CONCLUSION

These findings appear to indicate an equivalent efficacy for celecoxib and ketoprofen for the reduction of peri-prosthetic ossifications. Based on these results, a randomized prospective comparative study can be undertaken without risk of losing effective prevention in one group. This prospective study should enable a more precise evaluation of treatment equivalence and quantify any potential gain in morbidity obtained with celecoxib.

A new oral direct thrombin inhibitor, dabigatran etexilate, compared with enoxaparin for prevention of thromboembolic events following total hip or knee replacement: the BISTRO II randomized trial

BACKGROUND

Dabigatran etexilate is an oral direct thrombin inhibitor undergoing evaluation for the prevention of venous thromboembolism (VTE) following orthopedic surgery.

METHODS

In a multicenter, parallel-group, double-blind study, 1973 patients undergoing total hip or knee replacement were randomized to 6-10 days of oral dabigatran etexilate (50, 150 mg twice daily, 300 mg once daily, 225 mg twice daily), starting 1-4 h after surgery, or subcutaneous enoxaparin (40 mg once daily) starting 12 h prior to surgery. The primary efficacy outcome was the incidence of VTE (detected by bilateral venography or symptomatic events) during treatment.

RESULTS

Of the 1949 treated patients, 1464 (75%) patients were evaluable for the efficacy analysis. VTE occurred in 28.5%, 17.4%, 16.6%, 13.1% and 24% of patients assigned to dabigatran etexilate 50, 150 mg twice daily, 300 mg once daily, 225 mg twice daily and enoxaparin, respectively. A significant dose-dependent decrease in VTE occurred with increasing doses of dabigatran etexilate (P < 0.0001). Compared with enoxaparin, VTE was significantly lower in patients receiving 150 mg twice daily [odds ratio (OR) 0.65, P = 0.04], 300 mg once daily (OR 0.61, P = 0.02) and 225 mg twice daily (OR 0.47, P = 0.0007). Compared with enoxaparin, major bleeding was significantly lower with 50 mg twice daily (0.3% vs. 2.0%, P = 0.047) but elevated with higher doses, nearly reaching statistical significance with the 300 mg once-daily dose (4.7%, P = 0.051).

CONCLUSIONS

Oral administration of dabigatran etexilate, commenced early in the postoperative period, was effective and safe across a range of doses. Further optimization of the efficacy/safety balance will be addressed in future studies.

Ximelagatran, a new oral direct thrombin inhibitor, for the prevention of venous thromboembolic events in major elective orthopaedic surgery. Efficacy, safety and anaesthetic considerations

The oral direct thrombin inhibitor ximelagatran shows great promise for prevention of venous thromboembolic events following major elective orthopaedic surgery. Its consistent and predictable pharmacokinetics and pharmacodynamics across a wide range of patient populations allow administration with fixed dosing and with no coagulation monitoring. In orthopaedic surgery clinical trials, ximelagatran was effective and well tolerated compared with standard therapy, with dose and timing relative to surgery important factors in determining its optimal profile. In European trials, an initial 3-mg postoperative dose of subcutaneous melagatran, the active form of ximelagatran, followed by oral ximelagatran 24 mg twice daily achieved similar efficacy and safety to enoxaparin. Although the risk of spinal haematoma following neuraxial anaesthesia is rare, it is increased by the concomitant use of anticoagulants. In orthopaedic surgery trials with ximelagatran to date, complications such as spinal haematoma have not been reported. The pharmacokinetic profile of ximelagatran suggests that concurrent use with neuraxial anaesthesia should require no further precautions than those currently necessary with low-molecular-weight heparin.

The direct thrombin inhibitor melagatran followed by oral ximelagatran compared with enoxaparin for the prevention of venous thromboembolism after total hip or knee replacement: the EXPRESS study

BACKGROUND

Ximelagatran and its subcutaneous (s.c.) form melagatran are novel direct thrombin inhibitors for the prevention and treatment of thromboembolic disease.

METHODS

In a double-blind study, 2835 consecutive patients undergoing total hip or knee replacement were randomized to either melagatran/ximelagatran or enoxaparin. Melagatran 2 mg was started immediately before surgery; 3 mg was then administered postoperatively, followed by 24 mg of oral ximelagatran b.i.d. beginning the next day. Enoxaparin 40 mg, administered subcutaneously o.d., was started 12 h before surgery. Both treatments were continued for 8-11 days. The main efficacy outcome measures were major venous thromboembolism (VTE); [proximal deep vein thrombosis (DVT), non-fatal and/or fatal pulmonary embolism (PE), death where PE could not be ruled out], and total VTE (proximal and distal DVT; PE; death from all causes). DVT was detected by mandatory bilateral ascending venography at the end of the treatment period or earlier if clinically suspected. The main safety outcome was bleeding.

RESULTS

The rates of major and total VTE were significantly lower in the melagatran/ximelagatran group compared with the enoxaparin group (2.3% vs. 6.3%, P = 0.0000018; and 20.3% vs. 26.6%, P < 0.0004, respectively). Fatal bleeding, critical site bleeding and bleeding requiring reoperation did not differ between the two groups. 'Excessive bleeding as judged by the investigator' was more frequent with melagatran/ximelagatran than with enoxaparin.

CONCLUSIONS

In patients undergoing total hip or knee replacement, preoperatively initiated s.c. melagatran followed by oral ximelagatran was significantly more effective in preventing VTE than preoperatively initiated s.c. enoxaparin.

Blood loss in total hip arthroplasty for rapidly destructive coxarthrosis

We studied the perioperative blood loss in 100 total hip arthroplasties performed for rapidly destructive coxarthrosis and compared it with the blood loss in 100 total hip arthroplasties for regular coxarthrosis. The treatment protocol was identical in both groups. Total blood loss was calculated as the compensated blood loss (volume transfused during and immediately after surgery) and the non-compensated blood loss using Nadler and Mercuriali formula. The mean blood loss calculated in milliliters of red blood cells (100% haematocrit) was 578 ml in regular coxarthrosis and 945 ml in rapidly destructive coxarthrosis. The blood loss after total hip arthroplasty is greater when surgery is performed for rapidly destructive coxarthrosis than for regular coxarthrosis (P < 0.001).

[Autologous blood transfusion]

Autologous blood transfusion techniques are the principal means of reducing allogeneic blood exposure. Those techniques were developed in order to prevent the risk of contamination by viruses, mainly HVB, HCV and HIV. However that risk has become so small that all studies show an exorbitant cost/efficiency ratio. Autologous blood transfusion would therefore be of no interest in terms of public health but a recent experimental study suggested a possible transmission of the BSE agent through blood. Until the matter is settled, the precaution principle means we should prefer alternative techniques to allogeneic blood whenever possible, hence a renewed interest in autologous transfusion.

[Preoperative strategy for homologous blood salvage and peri-operative erythropoietin]

The amount of transfused blood is related to blood loss calculated for the specific type of surgical procedure, transfusion hematocrit trigger and patient's red blood cell mass on the day before surgery. To optimise the benefit/cost and benefit/risk ratios of blood transfusion, a correct prescription must be done in accordance with the patient's red blood cell mass and surgical blood loss. Indeed, there is a clear need to define the appropriate uses of blood management methods and to seek new methods of improving perioperative blood management. The number of moderately anaemic patients undergoing surgery is currently thought to be 20%. Where transfusion requirements are estimated at two to three blood units, as for instance in the most common types of orthopaedic surgery, preoperative haemoglobin is the key factor governing transfusion needs. In this case, the simplest approach is to prescribe Epoetin Alfa subcutaneous at a dose of 600 IU/kg/week starting three weeks before the surgery. In addition, it is important in all cases to give concomitant iron supplements. Concomitant use of other methods to decrease allogeneic blood requirements is of no value. Obviously, the higher the haematocrit the day prior to surgery, the higher the patient's RBC mass and the greater the patient's permitted blood loss, decreasing the transfusion trigger. In this way, allogeneic blood loss is reduced, but without the need for the patient to attend the blood transfusion center and to undergo laboratory screening and testing of donated blood, and without the risk of inducing preoperative anaemia compared with sequential autologous blood donation. But, to optimise the benefit/cost ratio, we try to define precisely the patient populations likely to benefit from preoperative erythropoietin. Using different examples, management is proposed with algorithms.

A comparison of recombinant hirudin with a low-molecular-weight heparin to prevent thromboembolic complications after total hip replacement

BACKGROUND

Patients who undergo total hip replacement have a high risk of thromboembolic complications. Recombinant hirudin (desirudin), a specific inhibitor of thrombin, represents a new development in antithrombotic therapy. We compared the efficacy and safety of desirudin with those of a low-molecular-weight heparin (enoxaparin) for the prevention of thromboembolic complications in patients undergoing primary total hip replacement.

METHODS

Both treatments, which were assigned in a randomized, double-blind manner, were started preoperatively: enoxaparin on the evening before surgery, and desirudin within 30 minutes before the start of surgery. The dose of desirudin was 15 mg subcutaneously twice daily, and the dose of enoxaparin was 40 mg subcutaneously once daily. The duration of treatment was 8 to 12 days. Deep-vein thrombosis was verified by bilateral venography performed at the end of the treatment period or earlier, if there were clinical signs of deep-vein thrombosis.

RESULTS

At 31 centers in 10 European countries, 2079 eligible patients were randomly assigned to receive desirudin or enoxaparin. A total of 1587 patients were included in the primary analysis of efficacy. In the desirudin group, as compared with the enoxaparin group, there was a significantly lower rate of proximal deep-vein thrombosis (4.5 vs. 7.5 percent, P=0.01; relative reduction in risk, 40.3 percent) and a lower overall rate of deep-vein thrombosis (18.4 vs. 25.5 percent, P=0.001; relative reduction in risk, 28.0 percent). The safety profiles were similar in the two treatment groups.

CONCLUSIONS

When administered 30 minutes before total hip replacement surgery, desirudin is more effective than enoxaparin in preventing deep-vein thrombosis.

[Medical environment of total hip prosthesis]

Total hip replacement is an extremely frequent operation for the treatment of degenerative joint disease. Indication for surgery must take into account the patient's general status, associated diseases, multiple joint involvement, and the efficacy and tolerance to medical treatments. The decision to operate is taken together by the physician and the patient. The degree of functional impairment and the patient's age are important factors. The patient must be informed that the period of hospitalization will be approximately 15 days and that good results are obtained in approximately 98% of the cases. Preoperative consultation with the anesthesist will focus on associated diseases with special attention to possible infectious foyers. Early post operative care includes a 48 hour antibiotic reginien, thromboprophylaxy with low molecular weight heparin for 3 days followed by anti-vitamin K for 6 weeks, and non-steroid antiinflammatory drugs for 5 days of up to 6 weeks in case of suspected risk of ossification. At mid-term, complications may include hematomas, infection and luxation. The fixation may also fail in certain cases where transtrochanter access was used. Long-term follow-up monitors for possible late onset infection and late luxations which usually result from prosthesis wear and more rarely from muscular causes.

[Preoperative hemodilution by erythrocytapheresis with homologous blood saving in total hip arthroplasty]

OBJECTIVES

To compare three techniques for decreasing homologous blood requirements in total hip arthroplasty (THA), including preoperative autologous donation (PAD), preoperative acute normovolaemic haemodilution with erythrocytapheresis (erythro) and intraoperative normovolaemic haemodilution (haemo).

STUDY DESIGN

Prospective clinical trial.

PATIENTS

The study included 45 patients scheduled for THA, under general anaesthesia and operated on by the same surgeon. The patients were allocated into three groups of 15 each.

METHODS

Blood loss was assessed, during surgical procedure, by the weight of sponges and, the amount of blood collected in the suction bottles during and after surgery. The haemoglobin concentration was measured at the time of preoperative assessement (d-30), just prior to surgery (d-1), in the recovery room (d+3h), and 1, 3, and 8 days later (d8). The transfusion end-point in the three groups was to obtain a haemoglobin concentration of 100 g.L-1 from d+3h until d8. Every pack of red blood cells transfused was weighed and its haematocrit assessed to determine the accurate volume of red blood cells.

RESULTS

In the three groups haemoglobin concentration was similar from d+3h until d8. In the PAD group, no patient required homologous blood transfusion. There was no significant difference between the two other groups in the mean volume of homologous red blood cells required (308 +/- 197 mL in erythro group and 331 +/- 202 mL in the haemo group, respectively). The intraoperative blood loss was significantly higher (P = 0.001) in the erythro group: 914 +/- 305 mL vs 665 +/- 263 in the PAD group and 512 +/- 146 mL in the haemo group, respectively. There was an inverse correlation between haematocrit at d-1 and intraoperative bleeding (r = -0.7) (P = 0.0001). The distribution of the points was fitted as an exponential curve.

CONCLUSIONS

In THA, PAD is obviously the best technique to avoid homologous blood transfusion. However, when PAD is not feasible, removal of blood prior to surgery does not decrease requirements of homologous blood, as intraoperative blood loss is higher. Our results strongly question the use of major haemodilution during a surgical procedure exposing a major blood loss.

Shivering threshold during spinal anesthesia is reduced in elderly patients

BACKGROUND

Both accidental and perioperative hypothermia are common in the elderly. The elderly are at risk because their responses to hypothermia may be delayed or less efficient than in those of younger subjects. For example, the vasoconstriction threshold during isoflurane anesthesia is approximately 1 degree C less in elderly than younger patients. However, the extent to which other cold defenses are impaired in the elderly remains unclear, especially in those older than 80 yr. Operations suitable for spinal anesthesia provided an opportunity to quantify shivering thresholds in patients of varying ages. Accordingly, the hypothesis that the shivering threshold is reduced as a function of age during spinal anesthesia was tested.

METHODS

Twenty-eight ASA Physical Status 1-3 patients undergoing lower extremity orthopedic procedures were studied. Spinal anesthesia was induced without preanesthetic medication, using bupivacaine sufficient to produce a dermatomal level near T9. Electrocardiogram signals were recorded at 10-min intervals. Subsequently, an observer masked to patient age and core temperature identified the onset of sustained electromyographic artifact consistent with shivering. The tympanic membrane temperature triggering shivering identified the threshold.

RESULTS

Three patients did not shiver at minimum core temperatures exceeding 36.2 degrees C. Fifteen patients aged < 80 yr (58 +/- 10 yr) shivered at 36.1 +/- 0.6 degrees C; in contrast, ten patients aged > or = 80 yr (89 +/- 7 yr) shivered at a significantly lower mean temperature, 35.2 +/- 0.7 degrees C (P = 0.002). The shivering thresholds in seven of the ten patients older than 80 yr was less than 35.5 degrees C, whereas the threshold equaled or exceeded this value in all younger patients (P = 0.0002).

CONCLUSIONS

Age-dependent inhibition of autonomic thermoregulatory control in the elderly might be expected to result in hypothermia. That it usually does not suggests that behavioral regulation (e.g., increasing ambient temperature, dressing warmly) compensates for impaired autonomic control. Elderly patients undergoing spinal anesthesia, however, may be especially at risk of hypothermia because low core temperatures may not trigger protective autonomic responses. Furthermore, hypothermia in the elderly given regional anesthesia may not be perceived by the patient (who typically feels less cold after induction of the block), or by the anesthesiologist (who does not observe shivering). Consequently, temperature monitoring and management usually is indicated in these patients.

[Comparison of Orth-Evac and Solcotrans Plus devices for the autotransfusion of blood drained after total knee joint arthroplasty]

Surgical wound blood which is ched through drains after total knee replacement surgery with a tourniquet may be returned to the patient using special collecting devices. This study aimed to compare two systems, Orth-Evac and Solcotrans Plus an to assess the safety of the reinfusion of non washed blood cells. It included 30 patients scheduled for total knee replacement surgery, free from tumoral or coagulation disease and allocated randomly in three groups of 10 each: the Orth-Evac group (OGr), the Solcotrans Plus group (SGr) and the Control group (CGr). The devices, not containing an anticoagulant, were connected to the deep suction drains in the operating room, after skin closure and before the tourniquet removal. The salvaged blood was reinfused in the subsequent six hours via a 40 microns filter. The volume of collected blood was measured and homologous blood was added as required, to maintain a hematocrit of 30%. A blood sample was obtained the day before surgery (D - 1), before reinfusion (D0), two hours later (D + 2h), one day later (D + 1), and from the collecting device before reinfusion. The statistical analysis used the Kruskal-Wallis test and Steel-Dwass procedure to confirm the difference between two groups. The three groups did not differ in age, weight, height and gender. The volume of salvaged and autotransfused blood was 925 +/- 156 mL in OGr and 605 +/- 178 mL in SGr respectively, transfusion of homologous blood was required in two patients of OGr, four of SGr and six of CGr. At D + 1, the hematocrit was comparable in all groups (OGr = 28%, SGr = 28.2% and CGr = 28.5%).(ABSTRACT TRUNCATED AT 250 WORDS)

Nifedipine and intraoperative core body temperature in humans

BACKGROUND

Initial anesthetic-induced hypothermia results largely from core-to-peripheral redistribution of heat. Nifedipine administration may minimize hypothermia by inducing vasodilation well before induction of anesthesia. Although vasodilation would redistribute heat to peripheral tissues, thermoregulatory responses would maintain core temperature. After equilibration, the patient would be left vasodilated, with a small core-to-peripheral temperature gradient. Minimal redistribution hypothermia may accompany subsequent induction of anesthesia, because heat flow requires a temperature gradient. In contrast, similar vasodilation concurrent with anesthetic-induced vasodilation may augment redistribution hypothermia. Accordingly, the authors tested the hypothesis that nifedipine treatment for 12 h before surgery would minimize intraoperative redistribution hypothermia, whereas nifedipine treatment immediately before induction of anesthesia would aggravate hypothermia.

METHODS

Patients undergoing hip arthroplasty were randomly assigned to: (1) 20 mg long-acting nifedipine orally 12 h before surgery, and 10 mg sublingually 1.5 h before surgery (n = 10); (2) nifedipine 10 mg sublingually just before induction of anesthesia (n = 10); and (3) no nifedipine (control, n = 10). Anesthesia was maintained with isoflurane and 60% nitrous oxide. Administered intravenous fluids were heated, but the patients were not otherwise actively warmed.

RESULTS

Core temperature decreased 0.8 degree C in the first hour of surgery in the patients given nifedipine the night before and the morning of surgery, which was significantly less than in the control group (1.7 degree C in the first hour). In contrast, core temperature decreased 2.0 degrees C in the first hour of surgery in the patients given nifedipine immediately before induction of anesthesia. During the subsequent 70-130 min of anesthesia, core temperature decreased at roughly comparable rates in each group. After 130 min of anesthesia, core temperature in the two nifedipine-treated groups differed by 1.6 degrees C, and the temperatures in all three groups differed significantly.

CONCLUSIONS

Vasodilation induced by nifedipine well before induction of anesthesia minimized redistribution hypothermia, presumably by decreasing the core-to-peripheral tissue temperature gradient. In contrast, redistribution hypothermia was aggravated by administration of the same drug immediately before induction of anesthesia. Drug-induced modulation of vascular tone thus produces clinically important alterations in intraoperative core temperature.

[Comparison of effects of Elohes and albumin on hemostasis in orthopedic surgery]

A prospective study was carried out to determine the effects of Elohes, a low molecular weight hydroxyethylstarch, on haemostasis. Sixteen patients due to undergo total hip replacement were randomly assigned to one of two groups: group A, who were to receive up to 21 of 4% albumin to replace blood loss, and group E, 1.51 of Elohes. Patients were then given concentrated red cell packs (RCP) and lactated Ringer's solution so as to have a haematocrit value of 30%, up to the fifth postoperative day. The amount of blood lost intraoperatively was calculated by weighing the swabs and measuring the volume aspirated. Haemostasis was investigated on the eve of surgery, 3 hours afterwards, and then every second day (days 1, 3 and 5). Total blood loss and the number of RCP transfused were similar in both groups: 1,517 +/- 425 ml and 3.5 RCP, and 1,428 +/- 250 ml and 3.25 RCP in groups A and E respectively. Blood albumin concentrations fell in group E as expected, the starch diluting blood proteins. Bleeding time (Simplate), activated partial thromboplastin time, prothrombin time changed in the same way in both groups throughout the study period after infusion of either Elohes or albumin. The concentrations in factors II, V, VII and X fell by 30% three hours after surgery. Values returned to normal between days 1 and 3, the concentrations of some factors rising to values greater than preoperative values because of the postoperative inflammatory process (fibrinogen, factor VIII von Willebrand). However, there were no significant differences between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

[Effects of nifedipine premedication on peroperative hypothermia]

The intraoperative time-course of core temperature in patients premedicated with nifedipine (n = 30) was compared to that of control patients (n = 30). Distal oesophageal temperature (TCORE) was recorded every five minutes during total hip replacement in 60 adults ranked ASA 1 to 2. Patients in the control group were only premedicated with 100 mg of oral hydroxyzine. The treatment group consisted of 30 patients taking nifedipine for blood pressure control or coronary insufficiency. They were given 10 mg sublingual nifedipine as well as the hydroxyzine premedication. Anaesthesia was induced with thiopentone, fentanyl and vecuronium, and maintained with nitrous oxide in oxygen and halothane in a semi-closed circuit. The slopes of the time-course for TCORE were established for each patient, using two linear regressions, between 0 and 0.5 h and from 1 to 2 h. The two groups did not differ in age, weight, ambient temperature, blood pressure, heart rate, and volume of unwarmed blood transfused. TCORE differed significantly from the 25th minute on until the end of the study period. Contrary to all expectation the TCORE at 2 h was higher in the nifedipine group (34.85 +/- 0.09 degrees C) than in the control group (34.01 +/- 0.14 degrees C, p < 0.001). TCORE decreased more rapidly in the control group during the first study interval (0 to 0.5 h), -1.50 +/- 0.60 degrees C.h-1 vs -2.34 +/- 1.02 degrees C.h-1 (p < 0.001). The second slopes did not differ particularly (-0.96 +/- 1.32 degrees C.h-1 vs -0.90 +/- 0.42 degrees C.h-1 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

[Blood loss and nausea during legal abortion]

The efficiency of oxytocic drugs in therapeutic abortion was studied in 113 women who were randomly assigned to either a control group (n = 44) receiving no oxytocic drugs, a group (n = 36) receiving 0.2 mg ergometrine by slow intravenous injection, or a group (n = 33) given 5 units oxytocin in a intravenous infusion throughout the procedure. The three groups were comparable with regard to the age of patients, the age of pregnancies and parity. The surgical procedure was the same in all three groups and carried out by the same surgeon. General anaesthesia was obtained with an infusion of 500 mg methohexitone and 500 micrograms fentanyl in 500 ml isotonic dextrose solution at a rate of 3 ml X min-1. The anaesthetic requirements were 2.94 +/- 0.80 micrograms X kg-1 fentanyl and 2.94 +/- 0,80 mg X kg-1 methohexitone. The criteria studied were the blood loss as measured by the volume aspired, the presence or absence of nausea and vomiting after the procedure, the age of pregnancy and the total amount of anaesthetic drugs given. No correlation was found between the amount of anaesthetic drugs given and the frequency of nausea and vomiting, and between the amount of blood lost (r = 0.287; ddl = 111; alpha = 17.322). The study did not, therefore, confirm the reputation of oxytocic drugs in reducing the bleeding. It seemed that, in therapeutic abortion, spontaneous uterine contraction was sufficient to control the bleeding. But a significant correlation was found between the amount of blood lost and the age of the pregnancy (r = 0.399; ddl = 111; alpha less than 1%).