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Biomedical subjects

D S Mulder

Publications and source records attributed to D S Mulder.

At least 55 records · Page 3Linked to original sources
PubMed1989

The nonextractable tined endocardial pacemaker lead.

With the advent of the tined pacemaker electrode to improve endocardial fixation, increasing difficulty in extracting them when needed has resulted in reports of serious complications. The authors reviewed their experience between January 1975 and January 1985. During this 10 year period, 942 pacemakers were inserted and 73 were reoperated upon. In the reoperations, repositioning or removal of tined electrodes was attempted 28 times. Repositioning or removal was not possible in 12 of the 28 cases (43%). In 22 of 28, the attempts to remove tined leads were carried out more than one month after the original implantations and in this group the failure rate was 54.5% (12 of 22). All attempts of removal within one month of implantation were successful (six of six). No leads were retained during the period between January 1984 and January 1985. All 12 retained leads were followed-up for five years, five of which were retained in the presence of pacemaker pocket infections. After removal of the power pack and lead distal to the cephalic or subclavian vein inlet, control of infection was achieved in all five cases. One patient was noted to have the retained lead migrate into the right pulmonary artery but was asymptomatic at 35 months after catheter migration was detected. Until now, no thoracotomy for lead extraction has been required in this series.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrodes, Implanted↗
PubMed1989

Mucociliary function in autotransplanted, allotransplanted, and sleeve resected lungs.

Tracheobronchial mucociliary function in dogs that underwent left upper sleeve lobectomy was compared with that of dogs that underwent left lung autotransplantation or allotransplantation (n = 5 each). Proximal airway clearance was measured by observing the movement of carbon particles through a bronchoscope. Preoperative and postoperative clearance rates for the right lungs in these dogs were unchanged. Although preoperative clearance rates in the transplanted left lungs were comparable with those of the right lungs, these left lungs were unable to clear the carbon particles during a 15-minute observation period 3 weeks postoperatively. In contrast, preoperative and postoperative clearance rates for the dogs that underwent sleeve resection were unchanged for both lungs. Mucus rigidity was studied by microrheometry and was found to be significantly increased postoperatively for samples collected from the autotransplanted and allotransplanted lungs than for samples collected from the untreated right lungs. These changes in mucus were noted for forces representing both normal ciliary beat and coughing. Viscoelastic properties of mucus were not significantly altered after sleeve lobectomy. Microscopic study showed squamous cell metaplasia and relative disappearance of bronchial glands distal to the anastomosis in all transplanted lungs. These changes were less pronounced in the sleeve resected bronchi. We conclude that changes in rheologic characteristics of mucus can impair mucociliary clearance and may be related to denervation after lung transplantation. Bronchial devascularization may have an additional effect of altering mucosal structures and function in the early postoperative period after lung transplantation. These effects are avoided by preserving peribronchial tissue in sleeve resection.

Animals↗
PubMed1988

Assessing multiple trauma: is the cervical spine enough?

This retrospective study of multiple trauma patients sustaining spinal column fractures was done to assess whether evaluation of the cervical spine alone is adequate. Sixty-three such patients were identified and further descriptive analyses performed. The majority of spinal fractures occurred not in the cervical spine, but in the thoracic and lumbosacral spine areas. Since a number of these spinal fractures have associated neurologic complications, only by prompt evaluation of the entire spinal column can further injuries be prevented. Based on our data, we feel that patients with multiple injuries and an altered sensorium should have the entire spine protected and evaluated radiologically before being cleared.

Adolescent↗
PubMed1988

The fate of venous repair after shock and trauma.

To assess the role of shock and trauma in the subsequent thrombosis of a venous repair, the following experiments were performed. Two groups of unsplenectomized dogs were studied: control dogs (Gr.C) underwent replacement of a segment of superficial femoral vein by an autogenous vein graft. Trauma group (Gr.T) dogs were subjected to hypovolemic shock using a modified Wiggers' technique and received standardized hindleg trauma. After resuscitation, venous repairs identical to Gr.C dogs were performed. Gr.T dogs exhibited a 78% thrombosis rate as opposed to 12% in Gr.C animals. To elucidate possible mechanisms, platelets were drawn from another ten animals, divided into similar groups, and labelled with Indium111-oxine. In Gr.T animals, graft activity increased over time and platelet distribution along the graft was homogeneous. These results contrasted markedly with those of Gr.C animals. We conclude that shock and trauma predispose venous repairs to failure and that altered platelet-endothelium interactions may be implicated.

Animals↗
PubMed1987

Prevention of septic ventilatory depression with naloxone.

Little is known of the endorphins' role in sepsis-induced respiratory distress and naloxone's effect as a treatment of it. Thirteen piglets were infused with live Escherichia coli at a rate of 2 to 10 X 10(8) colony-forming units per hour for six hours or until death and were divided into two groups: the septic control group (n = 8), and the naloxone-treated group (n = 5), which received 8 mg/kg/h of naloxone by continuous infusion. Hemodynamic parameters, the intrapulmonary shunt fraction (QS/QT), physiologic dead space (VD/VT), minute ventilation, and blood gas levels were measured. Lung lymph flow was obtained by cannulating the right lymphatic duct. The extravascular lung water weight was also measured. The results showed a significant reduction of QS/QT, VD/VT, and arterial carbon dioxide pressure at one hour and a significant increase of arterial carbon dioxide pressure and minute ventilation at 1, 3, and 4 hours in the naloxone-treated group, compared with the untreated septic group. None of the piglets in the naloxone-treated group developed ventilatory depression, while 75% of those in the untreated septic group did. Among the latter piglets, three died of apnea within one hour. These beneficial effects of naloxone are likely related to its action on the central and peripheral respiratory regulatory mechanisms. A transient protection of the cardiac output and relatively decreased extravascular lung water with naloxone treatment may also, in part, improve the ventilation-perfusion maldistribution and secondarily reduce QS/QT and VD/VT. We conclude that endorphins play a role in septic ventilatory depression and that naloxone is effective in ameliorating it.

Animals↗
PubMed1987

Surgery for thoracic hydatid disease: a North American experience.

The clinical course of 20 patients with 22 thoracic hydatid cysts operated on from 1957 to 1984, was reviewed. Follow-up extended to 27 years (mean, 11.6 +/- 1.5 years [+/- the standard error of the mean]) and was 90% complete. Most patients originated from countries in the Mediterranean region; 5 were native Canadians. The diagnosis was suspected in all but 3 patients preoperatively. Fourteen patients had 16 primary lung cysts, 4 had infected liver cysts with intrathoracic extension, 1 had synchronous unruptured liver and lung cysts, and 1 had a thymic cyst. Nine cysts were intact, whereas 13 had ruptured preoperatively. A variety of surgical procedures was performed, including eight wedge resections and nine lobectomies. There were no early deaths, and perioperative complications were infrequent. One patient with a hepatic cyst that had ruptured into the right pleural space and right lower lobe died at 7 months of massive echinococcosis of the liver and intraabdominal sepsis. There has been no evidence of thoracic recurrence in any of our long-term survivors, although 1 patient had undergone enucleation of a left lung cyst in Greece 15 years prior to her reoperation here for a lingular recurrence. We conclude that thoracic hydatid disease is a rare entity in northeastern North America. The prevalence of ruptured cysts and infected hepatic cysts involving the lung was higher than in most other series, thereby necessitating more aggressive surgical treatment. Nevertheless, morbidity was low, and recurrence of disease was uncommon in long-term follow-up.

Adolescent↗
PubMed1987

Caval tumor thrombus complicating renal cell carcinoma: a surgical challenge.

The surgical challenge of resection of renal cell carcinoma with vena caval invasion may require close cooperation between the urologist and cardiovascular surgeon. From 1977 to 1986, 13 patients with renal cell carcinoma and tumor thrombus invading the inferior vena cava (IVC) underwent radical surgical resection. In three of 13 patients the thrombus extended into the heart (right atrium two patients and right ventricle one patient). The tumor originated in the right kidney in 10 patients and in the left kidney in three patients. There were 10 men and three women with a mean age of 64 years (range, 46 to 75 years). Surgical management included midline incision, seven, with median sternotomy, four, and thoracoabdominal, two. After exposure of the renal vessels and IVC, all patients underwent radical nephrectomy. Two patients had caval sleeve resection, one had a partial caval resection, and seven had a 1 cm caval cuff. Planned cardiopulmonary bypass was used in three patients. The tumor thrombus was extracted by simultaneous atrial and caval approaches. One patient underwent unplanned emergency cardiopulmonary bypass after intraoperative cardiac arrest caused by a large tumor embolus of the pulmonary artery. No operative deaths occurred. Postoperative morbidity was significant in five of 13 patients, caval thrombosis in one, lower limb swelling in two, renal failure in one, and pulmonary edema in one patient. Two patients required long-term anticoagulation therapy for confirmed pulmonary emboli within 1 month of surgery. These complications resolved. The follow-up period ranged from 7 to 64 months with a mean of 36 months. Two patients died of metastatic disease at 24 and 48 months after surgery. Three patients are alive with metastatic disease at 6 to 64 months while one patient had a solitary metastatic lesion removed from the frontal lobe 4 years after nephrectomy and has been disease free a subsequent 18 months. Eight of 11 patients are disease free at 7 to 64 months (four patients greater than 52 months). Our 83% survival rate at a mean follow-up of 36 months suggests that this group of patients should not be denied aggressive resection. Documentation of tumor source and caval extension are essential to plan operative procedures, including use of cardiopulmonary bypass.

Aged↗
PubMed1986

Technique of right lymphatic duct cannulation for pulmonary lymph collection in an acute porcine model.

The pig is an increasingly preferred model for biomedical research, including studies for pulmonary pathophysiology. However, in piglets, the technique for cannulating the right lymphatic duct, which is subject to more anatomical variations and technically more demanding than that in dogs, has not been described. Our technique evolved to enable this collection of porcine lung lymph in acute experiments. The lymphatic ampulla is cannulated via one of the cervical lymphatics. The right lymphatic duct is invariably dorsal to the cranial vena cava and classically leads to the lymphatic ampulla. Yet in 18% of our pigs, cannulation was difficult or not feasible because the lymphatic duct either drained directly into the cranial vena cava at a distance from the lymphatic ampulla, or into the axillary lymph node of the first rib or the caudal deep cervical lymph nodes. Gently squeezing back regurgitated blood in the lymphatic ampulla before tying the suture and frequently withdrawing lymph with a syringe when the flow is small enabled us to collect clear lymph, usually immediately after completing the cannulation. The rate of lymph flow varied widely (1.7 +/- 0.6 ml/hr) and increased when the left atrial pressure was raised. The lymph protein was 2.8 +/- 0.2 g% with lymph/plasma protein ratio at 0.55 +/- 0.04. The anatomical variations encountered in our 34 dissections, as well as the technical maneuvers found to be useful in the successful cannulation and collection of the porcine lung lymph, are described in detail.

Animals↗
PubMed1986

Antibiotic prophylaxis in vascular surgery: pharmacokinetic study of four commonly used cephalosporins.

Plasma levels of antibiotics often do not correlate well with their tissue levels. To determine optimal antibiotic coverage for prophylactic effect in vascular surgery, we studied the tissue pharmacokinetics of four cephalosporins in dogs: cefazolin, cefoxitin, cefamandole, and moxalactam for 3 hours after a single (25 mg/kg) intravenous injection. The minimal inhibitory concentration (MIC) of these antibiotics for the three most common pathogens involved in graft infections (Staphylococcus aureus, S. albus, and Escherichia coli) and their tissue concentration (TC) in the plasma, muscle, subcutaneous tissue, and aortic wall were assayed. The data are presented as TC/MIC ratio. Cefoxitin and moxalactam failed to achieve an effective therapeutic TC/MIC ratio (greater than 10) for S. aureus and S. albus in all the tissues studied whereas cefoxitin and cefamandole were above therapeutic levels. All antibiotics achieved an effective therapeutic ratio against E. coli, but cefamandole performed better (p less than 0.05) than cefoxitin; the latter reached effective levels at 3 hours. Cefamandole attained the most effective bioactive aortic tissue levels when the three most common pathogens were considered together and should therefore be considered as an antibiotic agent of choice for prophylaxis in vascular surgery.

Animals↗
PubMed1986

Extrinsic civilian trauma to the larynx and cervical trachea--important predictors of long-term morbidity.

Injuries to the larynx and cervical trachea are uncommon, making the development of treatment protocols and subsequent data analysis in any one hospital difficult. This prompted a review of our experience with emphasis on variables related to long-term morbidity. The records of 20 patients with laryngotracheal injuries seen at the Montreal General Hospital from January 1974 to December 1984 were reviewed. The majority were young males (18 to 20 years old), and there was blunt trauma in 14 and penetrating trauma in six. The level of injury was laryngeal in 16 and tracheal in four. There were no airway-related deaths. One patient died with uncontrollable retroperitoneal hemorrhage before definitive repair of the tracheal transection. All but two of the remaining 19 patients had significant morbidity in the form of aphonia, dysphonia, or airway stenosis. The major factors contributing to the high morbidity were delay in diagnosis, anatomic level of injury, and associated multisystem trauma. A high index of suspicion, liberal use of fiberoptic bronchoscopy for diagnosis, and early airway control will lead to earlier diagnosis. Computerized tomography of the upper airway facilitates definitive surgical repair. Long-term followup is essential. Laryngeal trauma remains a major challenge.

Adult↗
PubMed1984

The effects of pulmonary atelectasis and reexpansion on lung cellular immune defenses.

Pulmonary atelectasis predisposes the lung to infection. This condition may be partly due to impaired cellular immune response of the collapsed lung segment. We postulated that atelectasis may affect alveolar macrophage (AM) antibacterial function. To test this hypothesis, atelectasis was induced in the right upper lobes of piglet lungs. Alveolar macrophages harvested by bronchoalveolar lavage of collapsed segments for up to 24 hours showed progressive depression of their phagocytic activity against Pseudomonas aeruginosa in vitro. However, their intracellular bactericidal activity did not change. Reexpansion of the atelectatic lobes with mechanical ventilation and 100% oxygen supplementation for four hours after six hours of atelectasis resulted in reversal of the impaired AM phagocytic activity. These observations presented insight into the mechanisms of susceptibility to lung infection in pulmonary atelectasis and the potential for its reversal.

Animals↗
PubMed1984

Clinical impact of intravenous hyperalimentation on esophageal carcinoma: is it worthwhile?

The coexistence of malignancy and dysphagia makes nutritional deprivation especially serious in patients with carcinoma of the esophagus. Intravenous hyperalimentation (IVH) is often given and should be of particular value in these patients. Sixty-four patients with carcinoma of the esophagus seen between January, 1975, and February, 1982, were studied retrospectively during their first hospitalization for the disease. Thirty-seven patients received IVH, and 27 did not. There were no significant differences at the time of admission to the hospital between the two groups with respect to age, sex, pathological status, and location of the carcinoma. Also, there was no difference in the incidence of hypoalbuminemia (less than 3 gm/dl) or lymphocytopenia (less than 1,500/mm3). More patients in the IVH group underwent surgical resection of the esophagus. Surgical intervention did not significantly influence hospital mortality. The IVH therapy reduced weight loss (p less than 0.05), but was associated with an increased incidence of pulmonary sepsis (p less than 0.05) and longer hospital stay. The incidence of hypoalbuminemia and lymphocytopenia increased between admission and the end of hospitalization, but it did not significantly differ between the groups. Thus, one cannot assume the effectiveness of IVH in this clinical setting, as its value was not demonstrated in this retrospective series. A prospective randomized study is warranted in view of the high cost and the doubtful clinical impact of an IVH regimen in patients with carcinoma of the esophagus.

Adenocarcinoma↗
PubMed1984

Pulmonary bacterial clearance and alveolar macrophage function in septic shock lung.

The association between the pulmonary bacterial clearance and the development of septic shock lung has been demonstrated in porcine and canine experimental models. In order to elucidate the role of the pulmonary reticuloendothelial system in bacterial clearance, the functions of alveolar macrophages (AM) obtained by bronchopulmonary lavage were studied. Five piglets were infused intravenously with Pseudomonas aeruginosa labeled with tritiated thymidine at 3 to 6 X 10(8) CFU/kg/min. Septic shock and manifestations like those of the adult respiratory distress syndrome developed within 1 h, and the pigs died within 2 to 3 h. Pulmonary bacterial clearance was 93% initially, and progressively decreased to 29%, as Pao2 decreased and lung water increased. The number of bacteria in the serial lung biopsy specimens increased steadily, although the distribution was not homogeneous. Differential centrifugations, repeated washings, and scintillation countings of the lavage fluid showed that in vivo AM phagocytosis was nil, despite the abundant bacteria found in the lavage fluid. However, when these AM were washed and tested in vitro in the presence of optimal concentrations of opsonin and oxygen, their phagocytic capability was well preserved, and was not significantly different from that of prebacterial infusion baseline values. It is concluded that in the septic shock lung, the lung clears bacteria not primarily by AM uptake but by other mechanisms, such as mechanical leakage into the pulmonary space, or by pulmonary intravascular leukocyte uptake. The apparent AM dysfunction in vivo is not intrinsic, and is likely to be caused by microenvironmental factors, such as lack of adequate opsonin and oxygen.

Animals↗
PubMed1984

Depression and delayed recovery of alveolar macrophage function during starvation and refeeding.

Malnourished patients are particularly vulnerable to pulmonary infection. In this study using a rat model, starvation was found to depress significantly the phagocytic capability of pulmonary alveolar macrophages which play important roles in the local cellular defenses of the lung. Intracellular bactericidal function of the alveolar macrophages was not affected. On refeeding, in spite of the rats regaining their body weights and the recuperation of certain systemic immune indexes, there was a delay in the recovery of alveolar macrophage phagocytic function.

Animals↗
PubMed1983

The effects of splenectomy and splenic implantation on alveolar macrophage function.

The effect of splenectomy on the ability of alveolar macrophages of young and adult rats to phagocytize Pneumococci, Types 3 and 14, and Pseudomonas aeruginosa was studied. Young animals showed a significant (15%) decrease in the phagocytosis of pneumococci type 14, 4 weeks after splenectomy. This depression increased to 30% in 6 weeks' time. Such depression was also noted when young splenectomized rat alveolar macrophages were challenged with Pseudomonas aeruginosa but not with type 3 pneumococci 6 weeks postsplenectomy. Three months following splenectomy in young animals, the rats were grown and they seemed to regain their normal phagocytic activity against pneumococci type 14. Adult rats also showed no alteration in their phagocytic activity against type 3 pneumococci. Autoimplantation of the spleen had a protective effect on the phagocytosis of type 14 pneumococci, and a nonsignificant effect on that of type 3. The present study postulates a modulatory role of the spleen on alveolar macrophage function. Splenectomy may cause the impairment of local lower respiratory immune function, making lungs vulnerable to specific bacterial invasion. Such splenic modulatory effect on alveolar macrophage phagocytic function seems to be age and antigen specific.

Aging↗