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Biomedical subjects

T R Todd

Publications and source records attributed to T R Todd.

At least 19 recordsLinked to original sources
PubMed1995

Role of open lung biopsy for diagnosis in lung transplant recipients: ten-year experience.

Between November 1983 and August 1993, The Toronto Lung Transplant Program performed 153 transplantations in 144 recipients: 53 single-lung transplantations (SLT) and 100 double-lung transplantations (DLT). Thirty-eight open lung biopsies (OLBs) were done in 32 (22% of all recipients): 19 in SLT (36% of SLT) 12 in DLT (12% of DLT), and 1 in a patient who had a SLT and then a double retransplantation. Six recipients underwent OLB twice: 1 DLT, 3 SLT, and 2 who had OLB both before and after retransplantation. Indication for 11 early OLBs (< or = 45 days postoperative) was persistent parenchymal infiltrates. Indications for 27 late OLBs (> 45 days postoperative) included progressive radiologic disease with clinical findings or progressive loss of pulmonary function (18), persistent poor graft function (3), mass or nodules (3), persistent infiltrates without functional loss (2), and persistent lymphocytosis in bronchoalveolar lavage (1). Open lung biopsy confirmed a previous clinical or pathologic diagnosis in 11, suggested a diagnosis in 2, yielded nonspecific information in 16, and provided different diagnosis in 9. New diagnosis that changed therapy was made in 1 of 11 early OLBs and in 8 of 27 late OLBs. These 9 diagnoses included in SLTs: bronchiolitis obliterans (2), bronchiolitis obliterans organizing pneumonia (1), malignant lymphoma (1), and chronic vascular rejection (1) in SLT, and bronchiolitis obliterans organizing pneumonia (3) and Burkholderia cepacia infection (1) in DLT. We conclude that OLB is of little value in the perioperative period but yields useful information in approximately 30% of patients when performed late.

Biopsy↗
PubMed1995

Exercise oximetry versus spirometry in the assessment of risk prior to lung resection.

BACKGROUND: Spirometry remains a standard method of assessing patient risk prior to lung resection despite its poor sensitivity and specificity. This study compares the relative ability of standardized exercise oximetry and spirometry--forced expiratory volume in the first second--to predict morbidity and mortality after lung resection. METHODS: The study comprised a retrospective review of 396 consecutive patients of whom 299 underwent both oximetry and spirometry. Oximetry was undertaken during standard exercise under the supervision of a single physical therapist. Spirometry identified 46 patients with a forced expiratory volume in the first second of less than 1.5 L who were considered to be high risk. Exercise oximetry was used to identify patients with arterial oxygen desaturation at rest, while walking on level ground, or while climbing two flights of stairs (n = 65). RESULTS: Compared with spirometry, exercise oximetry more reliably predicted home oxygen requirements (p < 0.001), need of admission to the intensive care unit (p < 0.05), prolonged hospital stay (p < 0.001), and respiratory failure (p < 0.05). Oximetry identified 50% of the patients who died, all of whom had a forced expiratory volume in the first second of greater than 1.5 L. Despite its superior predictive value, the sensitivity of oximetry remained low. CONCLUSIONS: We conclude that standardized exercise oximetry is a superior screen of the high-risk patient than spirometry (forced expiratory volume in the first second) prior to pulmonary resection when there are no other risk factors noted on initial history and physical examination. A prospective, randomized trial is required to substantiate this conclusion.

Critical Care↗
PubMed1992

Central neurogenic tumours of the thoracic region.

Of special concern in the management of neurogenic tumours arising in the thorax is spinal-cord compression resulting from either intraspinal lesions or vertebral-body destruction and collapse. A review of 16 cases disclosed three dumbbell tumours, six intrathoracic tumours, one case of neurofibromatosis with multiple intraspinal neurogenic tumours, two malignant neurogenic tumours with vertebral-body destruction causing spinal-cord compression and four foraminal lesions with central intraspinal (extradural) extension. There were 3 men and 13 women, ranging in age at the time of operation from 37 to 79 years. Three patients, of the six with intrathoracic tumours, were asymptomatic; the remaining 13 had preoperative symptoms ranging in duration from 3 weeks to 12 months (average, 9 months). Back pain with intercostal neuralgia was present in eight patients and neurologic signs were present in six patients. A routine chest radiograph was abnormal in 10 patients, and x-rays of the thoracic spine were abnormal in 4 of the other 6 patients. The tumour was excised surgically in all patients. Complications developed postoperatively in two patients: one had Horner's syndrome, transient paraparesis and bleeding; the other had a small subarachnoid-cutaneous fistula. The authors conclude that dumbbell neurogenic tumours and those causing vertebral-body destruction and collapse demand a multidisciplinary one-stage surgical approach. If the lesion is malignant and resection is not complete, radiotherapy or chemotherapy is necessary.

Adult↗
PubMed1991

Comparison of outcomes of double and single lung transplantation for obstructive lung disease. The Toronto Lung Transplant Group.

Single lung transplantation has recently been applied with success in patients with obstructive lung disease. Such patients were previously managed by bilateral pulmonary transplantation. Between November 1986 and January 1990, 18 patients underwent transplantation for obstructive lung disease in our center. Eleven double lung transplants and seven single lung transplants were performed in patients having a mean age of 43.4 and 44.1 years, respectively. Operative death occurred in two of 11 double lung transplantations and one of seven single lung transplantations. Each patient underwent preoperative and 3-month postoperative pulmonary function tests, arterial blood gas analyses, nuclear lung scans, and 6-minute walk tests. There was no difference in the preoperative values for any of these parameters. Double lung recipients had significantly higher forced expiratory volume in 1 second and forced vital capacity than single lung recipients. However, the ratios of forced expiratory volume in 1 second to vital capacity were not different. Arterial oxygen and carbon dioxide tension were not different between the two procedures. Whereas double lung transplantations caused a slight preponderance of perfusion to the right lung, the transplanted lung in single lung recipients received a mean of 79.5% +/- 12.3% of predicted flow and only 61.6% +/- 5.0% of predicted ventilation. Three-month 6-minute walk distances were markedly improved in both groups, with double lung recipients achieving 573.0 +/- 44.7 m in comparison with the 528.0 +/- 43.0 m achieved by the single lung recipients. Single lung transplantation is a satisfactory option in patients with obstructive lung disease and might offer significant advantages to the older patient population, in which risk of double lung transplantation is high.

Adult↗
PubMed1990

Effects of hypercarbia on arterial and alveolar oxygen tensions in a model of gram-negative pneumonia.

Inspired CO2 causing changes from hypo- to normocapnia has previously been shown to improve arterial O2 tension (PaO2) and to reduce alveolar-arterial O2 difference. The effect of further increases in inspired CO2 to hypercarbic levels has not been studied in inflammatory lung disease. Three days after induction of sublobar Pseudomonas pneumonia, Suffolk sheep were anesthetized and ventilated with a fixed-volume ventilator. After 2.5 h, CO2 was added to the inspired gas to raise arterial CO2 tension (PaCO2) to 60-65 Torr. Four hours later the CO2 was withdrawn and ventilation continued for an additional 2 h. Constant minute ventilation and inspired O2 fraction were maintained. Regional lung perfusion was measured by injection of radioactive microspheres. With the administration of CO2, PaO2 increased significantly from 65.5 to 77.5 Torr as did alveolar O2 tension (from 109.7 to 120.0 Torr) with no significant change in alveolar-arterial O2 difference. There were no significant changes in cardiac output, shunt fraction, O2 uptake, O2 delivery, respiratory quotient, or distribution of regional lung perfusion. We conclude that the increases in alveolar O2 tension and PaO2 with the added CO2 resulted from improved alveolar ventilation.

Animals↗
PubMed1990

Early postoperative management following lung transplantation.

The early (first 2 weeks) postoperative care of the lung transplant patient involves the management of immediate hemodynamic instability generated in some cases by cardiopulmonary bypass and in others by increases in thoracic pressure as a result of poor graft function and pulmonary noncompliance. Subsequently, emphasis is placed on the differential diagnosis and management of hypoxemia that may appear after the third day. The latter involves an appreciation of fluid balance as it relates to renal function and the knowledge and appreciation of immunosuppression.

Humans↗
PubMed1990

Airway complications after double lung transplantation. Toronto Lung Transplant Group.

We have had success with en bloc double lung transplantation in the management of selected patients with end-stage parenchymal pulmonary disease. Airway complications have been more prevalent in our own experience with double lung transplantation than in reports of combined heart-lung transplantation from other centers. Between November 1986 and March 1989, 16 patients underwent double lung transplantation. Allografts were preserved by topical hypothermic immersion in 12 patients and by pulmonary artery flush with cold crystalloid solution in the most recent four patients. Thirteen patients underwent tracheal anastomosis and the most recent three patients underwent bilateral bronchial anastomoses. Fatal ischemic necrosis of the donor trachea and both main bronchi developed in three patients. Preterminal airway ischemia developed in a patient who had systemic sepsis. Partial anastomotic dehiscence, which went on to form fibrous strictures necessitating endoscopic placement of silicone rubber airway stents, developed in two additional patients. Two other patients had late strictures and required subsequent placement of bifurcation stents. There was no relationship between development of airway complications and gas exchange in the donor lungs, lung ischemic time, early postoperative gas exchange, early postoperative mean pulmonary artery pressure, or frequency of early postoperative rejection. Severe postoperative hypotension occurred in five of eight patients with airway complications and in three of eight patients without airway complications.

Humans↗
PubMed1990

Single lung transplantation and closure of patent ductus arteriosus for Eisenmenger's syndrome. Toronto Lung Transplant Group.

A case report of the first single lung transplantation and closure of a patent ductus arteriosus for Eisenmenger's syndrome is presented. The operation was performed on Sept. 28, 1988. The patient was extubated on postoperative day 8, discharged from the intensive care unit on postoperative day 13, and discharged from the hospital on postoperative day 43, free of symptoms and without supplementary oxygen. Subsequent symptoms of dyspnea, presyncope, and fatigue recurred in association with subvalvular right ventricular outflow tract obstruction. Symptomatic improvement occurred gradually in association with reduction of the outflow tract obstruction. The patient is in New York Heart Association class I-II 12 months after the operation. The rationale, methods, and management of this patient are discussed, as well as the potential for application of this operation in similar settings.

Adult↗
PubMed1989

Use of silicone stents in the management of airway problems.

We report the use of a silicone rubber T tube for the management of complex airway problems in 47 patients during the past 15 years. The tube has been used for palliation in 11 patients with malignant obstruction of the airway, and as the sole treatment or as an adjunct to operation in 36 other patients. Based on the satisfactory results with the use of these tubes, we have utilized silicone stents in the bronchus and bifurcation prostheses at the carina. In the past, we have inserted the T tubes through a tracheostomy stoma. More recently, we have used a technique for endoscopic placement of the T tubes in which the horizontal limb is pulled out through the tracheostomy stoma. This technique facilitates introduction of the tube and maintains the airway during insertion. The use of silicone stents provides an important tool in the management of complicated airway problems, and we anticipate their increased use in the future.

Bronchi↗
PubMed1989

Augmented bacterial adherence to tracheal epithelial cells is associated with gram-negative pneumonia in an intensive care unit population.

Gram-negative pneumonia is a frequent complication of intubated patients in an intensive care unit (ICU), and the adherence of the bacterial pathogen to the respiratory epithelial surface is thought to be the critical initial step in the infection process. However, the correlation between bacterial adherence to tracheal epithelial cells (TEC) and the acquisition of pneumonia and whether intubation or its duration affects bacterial adherence to TEC is unknown. To examine these factors we initially established that the normal adhesion index range for Pseudomonas aeruginosa strain 492c adherence to TEC was zero to 18.83 cfu/TEC on the basis of the adhesion indices of 12 healthy volunteers and 20 surgical patients undergoing elective bronchoscopy. Forty-two analyses of the adhesion index for P. aeruginosa binding to TEC of 24 ICU patients were performed in this study. Analysis of the data indicated that the adhesion index was not correlated with intubation or the duration of intubation. However, an elevated bacterial adhesion index was significantly (p less than 0.001) correlated with pneumonitis. Pneumonitis was observed in 11 of the 12 patients who had an elevated or augmented bacterial adhesion index, whereas pneumonitis was observed in only one of 12 patients who had a normal adhesion index. The bacterial adhesion index was found to parallel the clinical situation in five patients where three patients developed high adhesion indices and acquired pneumonitis and two patients who initially had pneumonitis and elevated adhesion indices subsequently resolved their pneumonitis, and their adhesion indices fell to within the normal range.

Adult↗
PubMed1989

Transhiatal esophagectomy with gastric transposition for pharyngolaryngeal malignant disease.

Between 1981 and 1988, 41 patients underwent pharyngolaryngoesophagectomy with transhiatal gastric transposition and primary pharyngogastrostomy for hypopharyngeal, laryngeal, and cervical esophageal carcinoma. All patients had squamous cell carcinoma. Twenty-one patients had been treated initially by high-dose radiotherapy, but the tumor had either persisted or recurred. Four patients had previously received high-dose local radiotherapy to the neck for unrelated diseases, and in 16 patients no preoperative radiotherapy was given. There was one operative death. Anastomotic leaks developed in nine previously irradiated patients and three required flap reconstructions. Thirty patients had satisfactory swallowing postoperatively and three swallowed poorly. Delayed gastric emptying was a serious problem in two patients, necessitating pyloric bag dilatation in one and pyloroplasty in another. The average postoperative stay was 31 days. Thirty-seven percent survived longer than 12 months and 15% longer than 24 months. The probability of survival after 2 years is 35%. All deaths from recurrent disease occurred within 412 days postoperatively. At present, pharyngolaryngoesophagectomy with gastric transposition and primary pharyngogastric anastomosis offers the best chance for cure or palliation with acceptable morbidity and function for selected patients with advanced hypopharyngeal and laryngeal tumors.

Adult↗
PubMed1988

Physician-accompanied transport of surgical intensive care patients.

During a one-year period, 107 critically ill adult patients were transferred by a physician-accompanied transport system (PATS). Most patients required both tracheal intubation (82 per cent) and mechanical ventilation (71 per cent), while continuous vasopressor support was required in 27 per cent of transfers. Patients were classified as either potential organ donors (n = 21) or nondonor patients (n = 86). Nondonor patients had a mean time of patient transfer documented from the initial telephone contact to final arrival of the patient in the ICU of 345 +/- 221 min (range 65-1350 min); the mean time the patients were out-of-hospital was 73 +/- 58 min (range 5-330 min); the average distance travelled by the patient and PATS was 342 +/- 692 km (range 1-4000 km). Ultimate nonsurvivors of ICU admission (36 per cent) had shorter out-of-hospital times, shorter travel distances, and increased interventional support, as assessed by the Therapeutic Intervention Scoring System applied over the telephone and prior to departure at the referring hospital. Significant interventions were undertaken by PATS in 23 per cent of the nondonor patients prior to departure. During the transport process, there was at least a seven per cent morbidity (arrhythmia, hypotension, and vehicular difficulties) and a 0.9 mortality rate. We conclude that PATS offered significant advantages to this patient population through its ability to maintain acceptable morbidity and mortality rates while transferring patients over long distances and for prolonged periods of time.

Adolescent↗
PubMed1988

Technique of successful clinical double-lung transplantation.

Lung transplantation has become a successful method in the therapy for end-stage pulmonary disease. While single-lung transplantation provides benefit to patients with pulmonary fibrosis, bilateral lung transplants are required for septic or emphysematous lung disease. We describe the technique employed in 6 patients to transplant en bloc both lungs with the recipient heart left in place. The lungs are connected by a left atrial cuff, main pulmonary artery, and trachea. The completed implantation has a tracheal anastomosis securely wrapped in omentum, a left atrial anastomosis posterior to the heart, and a pulmonary artery anastomosis anteriorly. Airway ischemia resulted in the death of 1 patient. This procedure allows complete excision of all diseased pulmonary tissue, retention of the recipient's own heart, and separate excision of the donor heart for use in another recipient, thereby markedly increasing the supply of donor lungs for transplantation.

Adolescent↗
PubMed1988

Separate extraction of cardiac and pulmonary grafts from a single organ donor.

The scarcity of multiple-organ donors for perfused organ transplantation requires cooperation between various transplanting teams to maximize organ retrieval. We have developed a technique for the extraction of a cardiac and separate pulmonary graft from the same donor. These grafts can then be successfully implanted into two separate recipients. Our experience with 9 successful extractions and implantations is recorded.

Anastomosis, Surgical↗
PubMed1988

Ten-year experience with extracorporeal membrane oxygenation for severe respiratory failure.

In the last ten years, 17 patients with respiratory failure refractory to standard ventilator therapy have been treated with extracorporeal membrane oxygenation (ECMO) at the Toronto General Hospital. One patient was treated with ECMO twice. Four perfusions were veno-arterial, the remainder veno-venous. Perfusions ranged from 1 1/2 to 19 days, with a mean of six days. Ten patients died during treatment or soon after it was discontinued. Eight patients improved enough to allow resumption of standard ventilation, and four patients recovered sufficiently to have normal arterial blood gas levels on room air. Three are long-term survivors. Multiple surgical procedures have been performed successfully during use of ECMO including lung lavage, open lung biopsy and three lung transplants. Major complications include hemorrhagic diatheses and sepsis. The technique involves a substantial commitment of time and personnel but remains a tenable option for presumed reversible life-threatening respiratory failure.

Adolescent↗
PubMed1988

Mead Johnson Critical Care Symposium for the Practising Surgeon. 2. Complications of monitoring systems.

Current invasive monitoring techniques, although valuable in the care of critically ill patients, also have disadvantages. Complications of these techniques include errors in interpretation of measurements and complications of venous access and indwelling lines. To prevent these, the author recommends a standard routine for inserting and changing catheters, regular calibration of transducers and insertion of Swan-Ganz catheters with the balloon inflated with 1.0 to 1.5 ml of air.

Blood Pressure Determination↗
PubMed1988

Esophagectomy for complex benign esophageal disease.

We evaluated the use of total thoracic esophagectomy and replacement with stomach in a group of 21 patients between 1976 and 1986 who had undergone multiple unsuccessful esophageal operations. All patients had between one and four unsuccessful operations for benign esophageal disorders. Sixteen patients had primary motor disorders: achalasia in nine and esophageal spasm in seven. Of these patients, 11 also had recurrent gastroesophageal reflux and peptic esophagitis. Complicated reflux disease characterized by severe esophagitis, stricture, and impaired peristalsis without primary motor disorder occurred in five patients. In one patient a functionally impaired long-segment colon interposition was removed and replaced with stomach. Total thoracic esophagectomy and cervical esophagogastric reconstruction was done in all patients. The transhiatal approach was chosen for resection in 16 patients and thoracotomy was used in the other five. There was one perioperative death (5%), from massive aspiration 4 days after transhiatal esophagectomy. Other complications included transient anastomotic leak (three patients), tracheoesophageal fistula (one), recurrent nerve palsy (one), and transient hoarseness (two). Follow-up is complete between 1 and 10 years and reveals the following functional results: 12 patients good to excellent, seven fair, one poor. In this patient group in which multiple prior procedures have failed to improve severe incapacitating symptoms, we believe further attempts at hiatal reconstruction are unlikely to succeed. For this circumstance, we recommend total thoracic esophagectomy with the use of stomach as the replacement organ of choice.

Adult↗