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Biomedical subjects

D R Walker

Publications and source records attributed to D R Walker.

At least 37 records · Page 2Linked to original sources
PubMed1995

Results of pneumonectomy for cancer in patients with limited ventilatory function.

It is well established that patients with compromised pulmonary function have a greater incidence of morbidity and mortality following lung resection. The prognosis of 36 (9.7%) patients with poor respiratory function (forced expiratory volume in ls (FEV1) and FEV1/FVC (forced vital capacity) ratio were equal to or less than 50% of the predicted value) of a total of 369 patients who underwent pneumonectomy due to non-small cell lung carcinoma over 10 years were reviewed. All but three patients were male with a median age of 62.5 years. Right pneumonectomy was carried out in 12 (33%) and left in 24 (67%) patients. Median FEV1 and FEV1/FVC were 1.51 (46%) and 46.5% respectively. Three (8%) patients died within 30 days of surgery. The postoperative complication rate in patients with poor respiratory function was 44%. Nine (27%) of the hospital survivors died due to non-malignant causes (recurrent chest infection/respiratory failure) and 12 (36%) due to recurrent tumour. The cause of death in one patient was second primary lung tumour and it was unknown in three (9%) patients. Eight (24%) long-term surviving patients did not have severe respiratory symptoms; their FEV1 and FEV1/FVC were remeasured and revealed a median 1.05 l (38%) and 50%, respectively of the predicted value. Actuarial 5-year survival was 29%. Poor respiratory function is associated with postoperative complications and non-malignant deaths arising secondary to respiratory failure. The survival profile demonstrates that patients were successfully treated with pneumonectomy and suggests that surgery should not be withheld from those with limited lung function if detailed investigations predict adequate residual lung function.

Aged↗
PubMed1995

Influence of heparin thromboprophylaxis on plasma leucocyte elastase levels following lobectomy for lung carcinoma.

Recent in vitro studies and animal investigation indicate that plasma leucocyte elastase (PLE) can dissolve pulmonary structural proteins, such as elastin, and produce lesions in the lung similar to that seen in adult respiratory distress syndrome (ARDS) and emphysema. In contrast, heparin strongly inhibits PLE and protects elastin from elastolysis. On the basis of these findings, PLE levels were monitored in 24 patients with non-small cell lung carcinoma (NSCLC) undergoing lobectomy. Ten patients from Killingbeck Hospital (Group 1) received 5000 IU subcutaneous (s.c.) heparin commenced 2 h prior to surgery and continued at 8 h intervals until the patient was fully ambulatory. Fourteen patients from Bradford Royal Infirmary (Group 2) received no heparin as standard policy. There was no significant difference in pre-operative PLE levels between groups. The post operative PLE levels in both groups increased significantly (P < 0.02) on the first post operation day (POD). However, PLE levels of Group 2 were 2.5 to 5.3 times higher than those of Group 1 at each postoperative interval (first, third, and seventh POD) respectively (0.002 < P < 0.02). There was no difference in blood loss between groups (P = 0.17). These results indicate that post operative PLE activity is elevated in NSCLC patients following lobectomy and s.c. heparin administration as thromboprophylaxis may inhibit PLE activity post operatively without increasing blood loss. Therefore, heparin may have a role to play in protecting lung tissue against the pulmonary lesions caused by proteolytic activity of PLE, and theoretically reduce post-operative complications, such as ARDS or emphysema.

Aged↗
PubMed1995

Transcranial Doppler ultrasonography and transesophageal echocardiography in the investigation of pulmonary arteriovenous malformation in a patient with hereditary hemorrhagic telangiectasia presenting with stroke.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is associated with a high incidence of pulmonary arteriovenous malformations (PAVMs), which can be the underlying cause for cerebral ischemia or brain abscess. The diagnosis of these malformations may be difficult, as clinical or radiological findings may be absent. Transcranial Doppler ultrasound (TCD) with saline contrast and transesophageal echocardiography (TEE) with saline contrast are useful in identifying patients with right-to-left shunts and may help identify PAVMs. CASE DESCRIPTION: A 68-year-old woman with HHT presented with two strokes over a 1-year period. After the first stroke, a transthoracic echocardiogram with saline contrast demonstrated significant right-to-left shunt that was interpreted as a patent foramen ovale. After the second stroke, a TCD contrast study confirmed this right-to-left shunt; however, a TEE contrast study discovered an extracardiac shunt. Pulmonary angiography revealed a left lower lobe PAVM and three telangiectasias involving the right lung. The PAVM was subsequently embolized. Postembolization radiographic imaging showed complete occlusion of the feeding vessel to the PAVM. However, repeated contrast TCD and TEE demonstrated persistent right-to-left shunting. CONCLUSIONS: In our patient, stroke may have resulted from peripheral venous emboli passing through the PAVM or from endogenous thromboemboli originating within the PAVM. TCD and TEE contrast studies were helpful in judging the efficacy of catheter embolization therapy of PAVM. TCD and TEE with saline contrast may be clinically useful follow-up examinations for recurrence or development of new PAVMs.

Aged↗
PubMed1995

Impaired thermoregulation in Raynaud's phenomenon.

UNLABELLED: In an attempt to examine the role of the thermoregulatory apparatus in the etiology of Raynaud's phenomenon (RP), the authors exposed 15 women with RP and 12 controls to central body cooling and central body warming. Subjects were placed in an environmental chamber at 25 degrees C. Their right hand was placed in an annex of the chamber, which was insulated from the main chamber and maintained at a constant temperature of 25 degrees C throughout the experiment. Blood flow was measured in the digits of the right hand by venous occlusion strain gauge plethysmography and skin thermometry. Body temperature was measured with an oral thermometer. The temperature of the chamber was then increased to 35 degrees C and then reduced to 13 degrees C for twenty-five minutes with measurements repeated. Following this period patients were rewarmed in an ambient temperature of 35 degrees C for twenty minutes. RESULTS: subjects with RP had significantly lower blood flow at all stages of the test; moreover, their digital rewarming response following central cooling was considerably prolonged when compared with controls. Body temperature was lower and dropped significantly more in the RP group following the cold challenge. The authors conclude that subjects with RP have an impaired thermoregulatory mechanism. This may partially explain cold sensitivity.

Adult↗
PubMed1994

Magnesium flux caused by coronary artery bypass operation: three patterns of deficiency.

We undertook a study to evaluate the patterns of magnesium deficiency that may develop during and following coronary artery bypass operation without cardioplegia. In 18 patients intraoperative measurements of plasma magnesium and potassium concentrations and measurements of cardiac and skeletal muscle content of these ions were taken. The changes in plasma concentrations and excretion were evaluated postoperatively. Hemodilution at initiation of cardiopulmonary bypass caused a 17.3% decrease in plasma magnesium concentration (p < 0.01), which persisted until the first postoperative day. By the fifth postoperative day the level was 19.5% greater than the preoperative value. Urinary excretion of magnesium reflected changes in plasma magnesium concentration. Cardiac muscle content of magnesium decreased by 13.3%. Plasma potassium concentration was elevated by hemodilution (p < 0.01), and muscle potassium was not depleted. We conclude that three patterns of magnesium depletion occur: hemodilution, intraoperative cellular depletion, and postoperative cellular depletion. The findings support the need for magnesium supplementation during and after cardiac operation.

Coronary Artery Bypass↗
PubMed1994

Fate of patients with residual tumour at the bronchial resection margin.

The presence of microscopic deposits of tumour cells at the bronchial resection margin (BRM) may adversely affect the prognosis of patients. Residual tumour cells were identified at the BRM in 40 (5.4%) of 735 patients who had been operated on for non-small cell lung carcinoma (NSCLC). The extent of disease was stage I in 7 (17.5%), stage II in 21 (52.5%), stage IIIa in 10 (25%) and stage IIIb in 2 (5%) patients. Malignant cells were found to have infiltrated the submucosal lymphatics in 5 (12.5%) cases and the peribronchial tissue in the remaining 35 (87.5%). Fifteen (37.5%) patients received adjuvant radiotherapy (RT). Recurrence of the disease was diagnosed in 29 (72.5%) patients after a median of 17 months (range 3-111). The recurrence was local in 17 (59%) and distant in 12 (41%). The 5-year overall actuarial survival rate was 21.6% and was not affected by RT (P = NS). Only patients with stage IIIa disease and a positive bronchial stump had a significantly reduced 5-year survival rate compared to those with a negative stump, 0% vs 17% (P < 0.001). Tumour cells at the resection margin did not affect the survival in this cohort except those with stage IIIa disease, and the addition of adjuvant RT did not significantly affect its recurrence in patients with NSCLC.

Aged↗
PubMed1994

Effect of type of resection on plasma granulocyte elastase levels following surgery for non-small cell lung carcinoma.

The lung is the primary focus of complications associated with adult respiratory distress syndrome (ARDS) and increased activation of granulocytes has been implicated in the genesis of ARDS. In the present study, plasma granulocyte elastase levels were measured in 24 patients undergoing lung resection for non-small cell lung carcinoma. Pre-, peri- and post-operative assessments of plasma elastase levels were made of patients who underwent a partial resection (lobectomy, n = 13) and patients who underwent a complete lung resection (pneumonectomy, n = 11). Preoperatively, values were similar for both patient cohorts and did not differ from those of normal volunteers. However, immediately (1 h) post-operation, elastase levels in patients who had undergone pneumonectomy were significantly elevated (300% of baseline value, P < 0.005), whereas levels were unchanged in lobectomy patients. On the 1st post-operative day (POD), elastase levels had returned to normal in pneumonectomy patients, whilst lobectomy patients now exhibited increased plasma elastase levels which remained marginally increased until the time of discharge (P < 0.05). The determinants of granulocyte activation following lung resection remain to be elucidated but may potentially relate to ischemic reperfusion in patients undergoing lobectomy, or alternatively may simply reflect the extent of manipulation, compression and contusion of lung tissue.

Aged↗
PubMed1994

Systemic heparinization during peripheral vascular surgery: thromboelastographic, activated coagulation time, and heparin titration monitoring.

Fifteen patients (9 male, 6 female) undergoing peripheral vascular surgery were monitored during surgery for evidence of subclinical anticoagulation using the activated coagulation time (ACT), thromboelastography (TEG), and heparin titration monitoring. Assessments were made at 30-minute intervals before and after the occlusion clamp. Mean (+/- SD) ACT values preoperatively were 111 (17) seconds, and 10 minutes after 5,000 IU of heparin, the ACT was 264 (57) seconds (P < 0.001). Intraoperatively, there was a significant decline in ACT values at 30 minutes (ACT 228 [50] sec, P < 0.005) and 60 minutes (200 [46] sec, P < 0.001) postheparin. No significant difference in ACT was observed between samples drawn distally and proximally to the clamp. TEG profiles were abolished in all patients immediately following heparinization. However, in 2 patients nearly complete return of the TEG coagulation profile was observed prior to the termination of the procedure and was associated with ACT values less than 160 seconds. The heparin device was unable to accurately monitor heparin elimination at these low doses. Variability of patient response to heparinization necessitates the use of intraoperative monitoring of anticoagulation during peripheral vascular surgery.

Aged↗
PubMed1994

Neutrophil activation and morbidity in young adults with cyanotic congenital heart disease.

Young adults with cyanotic congenital heart disease have a high incidence of respiratory and haemostatic problems. Activated neutrophils release vasoactive and chemotactic factors which result in endothelial injury, lung parenchymal damage and the activation of platelets and coagulation pathways. To investigate the contribution of neutrophil activation to morbidity in young adults with cyanotic congenital heart disease, plasma neutrophil elastase levels were measured in 25 cyanotic patients and the results compared to patients with acyanotic heart disease and normal controls. Neutrophil elastase levels were significantly elevated in the group with cyanotic congenital heart disease (P < 0.001). Platelet activation was significantly increased in the patients with cyanotic heart disease (P < 0.001). Platelet aggregation was impaired only in those with haematocrits greater than 0.50 (P < 0.02). Whole blood coagulation, as determined by thrombelastography, was within normal limits. The reason for neutrophil activation in patients with cyanotic congenital heart disease is unclear, but activated neutrophils may contribute to the respiratory and haemostatic problems common to these patients.

Adult↗
PubMed1993

Noncardiogenic pulmonary edema complicating lung resection.

Postresectional pulmonary edema is a rare but potentially fatal complication of thoracic operations. In a retrospective study of 402 lung resections we have identified 11 cases of postresectional, noncardiogenic pulmonary edema. We have analyzed the individual data to test recognized hypotheses regarding this condition. Pulmonary edema occurred in 5.1% of right pneumonectomies, 4.0% of left pneumonectomies, and 1% of all lobectomies. In 2 patients the symptoms occurred immediately after operation; in the other 9 the mean interval to diagnosis was 43.4 hours. All 11 patients were in a positive fluid balance in the first 24 hours after operation (mean, 20.8 +/- 9.1 mL/kg). However, there was no significant difference between this value and the respective values for control groups of 20 patients having pneumonectomies and 20 patients having lobectomies in whom pulmonary edema did not develop. Our findings differ from other reported series in that perioperative fluid overload was not found to be a significant contributory factor in the development of postresectional pulmonary edema. We discuss other possible mechanisms for this phenomenon.

Aged↗
PubMed1993

Long-term results in the elderly following pulmonary resection for non-small cell lung carcinoma.

The long-term results of 647 patients undergoing pulmonary resection for non-small cell lung carcinoma (NSCLC) between 1980-1988 were reviewed. One hundred forty-five (22%) were elderly patients (70 years or more, group 1), with a mean age of 72.3 years (70-81) and the other 502 (18%) were younger (69 years or less, group 2) with a mean age of 61.4 (40-69) years. The male to female ratio was 4:1 in group 1 and 3:1 in group 2. The number of patients in group 2 (n = 234, 47%) who underwent pneumonectomy was significantly greater (P < 0.01), compared to group 1 (n = 47, 32%). Cardiopulmonary complications were more frequently observed in group 1 (19.3%) than in group 2 (7.4%), P < 0.05. Although cardiac complications (i.e. arrhythmias) were more common in the elderly group, pulmonary complications (retained secretions, atelectasis) occurred more commonly in the younger group. The overall hospital mortality in group 1 and group 2 was 8.9% and 5.3%, respectively (NS), and mortality following pneumonectomy in group 1 (10.6%) was similar to that of group 2 (7.6%) (NS). The 2- and 5-year overall actuarial survival rates were 61% and 30% in group 1 and 57% and 37% in group 2 (NS). Superior survival was achieved in patients in stage I of the disease in both groups. Cell type was not a determinant of long-term survival differences between the groups whereas type of operation (lobectomy) and sex (female) were.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗