Effect of cigarette smoking on subsequent postoperative thromboembolic disease in gynaecological patients

Defective Fibrinolysis in Venous Thrombosis

In previous studies a variety of attempts have been made to define laboratory tests which could predict patients who would develop deep vein thrombosis post-operatively. Such tests included the partial thromboplastin time, haematocrit and platelet adhesiveness. In this study patients undergoing gynaecological surgery were screened in advance with a panel of clinical measurements and laboratory tests and the development of DVT was noted using 125I-fibrinogen leg scanning. The values for the selected variables were analysed using logistic discrimination. The factors with the greatest prediction were the euglobulin lysis time, age, varicose veins, serum FR-antigen and percentage overweight for height.

When this formula was applied to a further group of patients it allowed a ‘high risk’ group to be defined and these were given low-dose heparin with a significant reduction in the incidence of post-operative DVT.

An unexpected finding was that patients who smoked cigarettes appeared to be protected from post-operative DVT.

Systemic lupus erythematosus in a multiethnic US cohort (LUMINA). XXV. Smoking, older age, disease activity, lupus anticoagulant, and glucocorticoid dose as risk factors for the occurrence of venous thrombosis in lupus patients

OBJECTIVE

Venous thrombosis is a relatively frequent and serious complication in systemic lupus erythematosus (SLE) that has been associated with the presence of antiphospholipid antibodies (aPL). However, venous thrombotic events can also be seen in patients without aPL, and only a few patients with aPL develop venous thrombosis. This study was carried out to ascertain other factors contributing to the development of venous thrombosis in SLE.

METHODS

Patients with SLE, ages > or = 16 years with < or = 5 years disease duration and of Hispanic, African American, or Caucasian ethnicity, from LUMINA (LUpus in MInorities, NAture versus nurture), a multiethnic, longitudinal study of outcome, were studied. Selected socioeconomic/demographic, clinical, laboratory, and treatment-exposure variables were compared between patients who developed and those who did not develop venous thrombotic events. Significant and clinically relevant variables were then entered into different multivariable models (Cox proportional hazards and unconditional stepwise logistic regression) to identify independent risk factors associated with the primary outcome. In another model, only patients who developed an event after enrollment (time 0) in the cohort were included.

RESULTS

Of 570 LUMINA patients, 51 developed at least 1 venous thrombotic event after SLE diagnosis. In univariable analyses, smoking (P = 0.020), shorter disease duration at time 0 (P = 0.017), serum levels of total cholesterol, low-density lipoprotein, and triglycerides (all P < 0.0001), and presence of lupus anticoagulant (LAC) (P = 0.045) were associated with venous thrombotic events. Survival analyses showed a time-dependent significant association of the primary outcome with smoking (P = 0.008) and a borderline significant association with the presence of LAC (P = 0.070). Multivariable models showed an independent association with smoking, age at time 0, disease activity over time, LAC, mean dose of glucocorticoids, and shorter disease duration at time 0.

CONCLUSION

Venous thrombotic events occur early in the course of SLE. Our data confirm the association between LAC and venous thrombotic events. Smoking, shorter disease duration, older age, disease activity over time, and higher mean daily glucocorticoid dose were identified as additional risk factors for the development of this vascular complication. These findings may have implications for the management of patients with SLE.

Postoperative intensive care admittance: the role of tobacco smoking

BACKGROUND

Smokers have been shown to have increased risk of intraoperative pulmonary complications and of a wide range of postoperative complications, but an increased risk of postoperative intensive care admittance has not yet been described. The aim of this study was to estimate the risk of pulmonary complications and postoperative intensive care admittance in smokers and non-smokers in a general and orthopaedic surgical population.

METHODS

A total of 4725 surgical patients were assessed. The following information was noted: age, sex and smoking status, history of heart and lung disease, ASA classification, type of anaesthesia, intensive care admittance and postoperative pulmonary or cardiovascular complications. A logistic regression model was used to determine the probability of intensive care admittance and pulmonary complications as a function of smoking status, age, and chronic heart and lung disease.

RESULTS

Of the patients, 39.9% were smokers, 45.5% were non-smokers and in 14.6% of the cases smoking status was unspecified. Postoperative intensive care admittance and pulmonary complications were found in 2.0% and 4.3% of the patients, respectively. Non-smokers were more often female (P<0.01), and smokers had a higher incidence of emergency surgical procedures (P<0.05). When applying multiple regression analysis, we found that smoking, age >65 years, and a history of chronic lung disease increased the risk of unplanned intensive care admittance (odds ratio 1.55, 12.52 and 2.73).

CONCLUSION

Our results indicate a relationship between a history of tobacco smoking and postoperative intensive care admittance.

The effects of cigarette smoking on anesthesia

Cigarette smoke contains over 4000 substances, some of which are harmful to the smoker. Some constituents cause cardiovascular problems, increasing the blood pressure, heart rate, and the systemic vascular resistance. Some cause respiratory problems, interfering with oxygen uptake, transport, and delivery. Further, some interfere with respiratory function both during and after anesthesia. Some also interfere with drug metabolism. Various effects on muscle relaxants have been reported. Risk of aspiration is similar to that of nonsmokers, but the incidence of postoperative nausea and vomiting appears to be less in smokers than in nonsmokers. Even passive smoking effects anesthesia. Best is to stop smoking for at least 8 weeks prior to surgery or, if not, at least for 24 hours before surgery. Anxiolytic premedication with smooth, deep anesthesia should prevent most problems. Monitoring may be difficult due to incorrect readings on pulse oximeters and higher arterial to end tidal carbon dioxide differences. In the recovery period, smokers will need oxygen therapy and more analgesics. It is time that anesthesiologists played a stronger role in advising smokers to stop smoking.

Deep-vein thrombosis after major non-cardiovascular thoracic surgery

The incidence of deep-vein thrombosis (DVT) verified by fibrinogen test was studied in 44 high-risk patients after major non-cardiovascular thoracic surgery. In eight patients (18%) a total of ten DVT appeared within the first postoperative week. Four thrombi were located at or above knee level. More extensive surgery was associated with higher DVT incidence than lesser operations (32% v. 8%). In patients belonging to blood groups B and AB, DVT was more common than in other blood groups. Five of the six unilateral DVT were detected on the same side as the thoracotomy. The findings suggest that DVT incidence after this kind of surgery may be of the same order as after major general surgery, indicating a need for thromboprophylactic measures.

Incidence of post-operative deep vein thrombosis in gynaecological oncology

Using 125I-fibrinogen scanning the incidence of post-operative DVT amongst patients with gynaecological malignancy was shown to be 37.9% which is substantially higher than the 10% to 15% expected in a general gynaecological population. Twenty per cent of the total group studied had isotopic evidence of bilateral venous thrombosis post-operatively. The inaccuracy of clinical diagnosis was demonstrated, and also the need to investigate both limbs if thrombosis was suspected. The incidence of post-operative DVT was found to be significantly lower in smokers (11.5%) compared with non-smokers (68.4%) (p less than 0.00025).

Thromboembolic complications in Cushing's syndrome

Thromboembolic events are thought to occur with increased frequency in Cushing's syndrome due to the predisposing factors, obesity, hypertension, a raised haematocrit and major surgery plus a 'hypercoagulable state'. To examine this postulate further we have studied 43 patients with Cushing's syndrome retrospectively and 10 patients prospectively to determine the incidence of arterial and venous thrombosis, both spontaneous and post-operative. Arterial events were noted in four cases (9%) and deep vein thrombosis or pulmonary thromboembolism (PTE) occurred in six cases (11%). Post-operative PTE occurred in 2.7% of all operations. These vascular complications tended to occur in the older patients with Cushing's syndrome. In our series, clinically significant thromboembolic episodes appear no more common than expected and the indications for prophylactic anticoagulation (the older and more obese patients) may not be different from other patients undergoing major surgery. An incidental finding was of a greater frequency of hypertension in Cushing's patients due to an adrenal adenoma.

Prediction and selective prophylaxis of venous thrombosis in elective gastrointestinal surgery

Clinical features were noted and routine and non-routine laboratory variables were measured before elective major gastrointestinal surgery in 63 patients aged 40 years or more. Deep-vein thrombosis (DVT), detected by routine 125I-fibrinogen leg scanning, developed in 21 patients. Five clinical variables but no laboratory variables were significantly associated with DVT: age; percent mean weight for age, sex, and height (%MW); presence of varicose veins; cigarette-smoking; and sex. The most useful discriminant index of these variables was age in years plus 1.3 x %MW. The index was validated prospectively in a further 41 patients, in 18 of whom DVT developed. The value of the index in selective prophylaxis was then assessed in a further 40 patients, of whom 24 (60%) with high-risk index received low-dose heparin (5000 units twice daily). DVT developed in 4 of the 40 patients, an incidence of 10% compared with the incidence of 37.5% (39 of 104) in the earlier studies with no prophylaxis.

Deep venous thrombosis after total hip arthroplasty: a prospective controlled study to determine the prophylactic effect of graded pressure stockings

Graded pressure stockings significantly reduced the incidence of venographically determined deep venous thrombosis (DVT) after total hip arthroplasty. Seventy-six patients were studied; the incidence of DVT was 54 per cent in 41 control patients and 20 per cent in 35 patients who wore stockings. Administration of blood during the operation and in the first 24 h after operation, if given in excess of blood loss, was associated with a significantly increased risk of developing DVT. The application of graded pressure stockings and the avoidance of unnecessary perioperative blood transfusion are worth while in the management of total hip arthroplasty.

Postoperative deep vein thrombosis caused by intravenous fluids during surgery

Using a new method of measuring whole blood clotting time, we have confirmed the findings of others, that blood clots faster when diluted with saline. A prospective trial was designed to test the hypothesis that intravenous saline peroperatively causes hypercoagulation and increases the risk of venous thrombosis. Sixty patients admitted for routine laparotomy were randomly allocated to either a group receiving intravenous fluids during or after operation (Wet), or a group receiving no intravenous fluids (Dry). The Wet patients became significantly more haemodilute and hypercoagulable than the Dry (P < 0.001), and these changes correlated. A postoperative deep vein thrombosis occurred in 30 per cent of the Wet patients, but in only 7 per cent of the Dry (P < 0.05). The need for intravenous fluids during uncomplicated surgery is probably unproved, and their greater use may have contributed to the increasing prevalence of venous thromboembolism.