Biomedical subjects
Publications and source records attributed to T R Todd.
We report two cases of middle mediastinal parathyroid ectopia associated with chronic renal disease. In both patients the diagnosis was delayed and prolonged due to the unusual location of the ectopic parathyroid tissue. The surgical approach was in error in 1 patient and corrected during the second procedure. We describe the surgical technique for exposing and excising parathyroid tissue from this area.
The intrusion into the pleural space by surgeons was hindered for several hundred years by the realization that there were major pathophysiological alterations in ventilation and in circulation. The nature of this abnormality, although described very early on in history, went unrecognized until the end of the nineteenth century. The performance of thoracic surgery prior to that time and the development of different modes of ventilatory support are testimony to the intuition and inventiveness of the surgeons of that day. It is hard for the modern thoracic surgeon to fully comprehend the challenges that faced the early surgeon back when there was no such thing as positive pressure ventilation or unilateral lung ventilation. This article traces the origins of ventilation in man and their application to the development of thoracic surgery.
BACKGROUND: In patients with apparently operable non-small cell lung cancer (NSCLC), clinicians often omit investigation for M disease in asymptomatic patients. Previous investigations have not specified in detail what is meant by "symptomatic," and this could differ between surgeons. We have investigated the extent to which surgeons' criteria differ for presence of symptoms. METHODS: Participating surgeons from seven centers, enrolled patients they judged "asymptomatic" in a randomized trial of investigational strategies for NSCLC. Patients completed a structured questionnaire describing symptoms of the central nervous system (CNS). In 685 patients, we documented CNS symptom recurrence after resectional surgery over 1 year of follow-up. RESULTS: Two centers enrolled only patients without even the mildest symptoms. Three centers took an intermediate approach, occasionally classifying patients with mild symptoms as "asymptomatic" and thus enrolling them in the trial. Two centers classified an appreciable number of patients with minimal symptoms, and occasionally with more than minimal symptoms, as "asymptomatic." Patients with even mild CNS symptoms were more likely to subsequently present with CNS metastases. CONCLUSIONS: Thoracic surgeons differ in their ideas of what may constitute the symptoms of M disease. Patients with structured questionnaire results that suggest symptoms of CNS disease are more likely to have CNS symptom recurrence after resectional surgery.
Lung volume reduction surgery for emphysema is evolving rapidly since its re-introduction in 1993. Lung transplantation remains a viable option for others with emphysema. The major difficulty facing surgeons lies in appropriate selection of patients for either procedure. The following paper represents an attempt by review of the literature and personal experience to describe some of the important features involved in patient selection. The current literature on patient selection for lung volume reduction surgery and transplantation for emphysema was reviewed, and the results within the University of Toronto Lung Volume Reduction Program were analyzed. The review suggests that the most reliable predictors of success are heterogeneous distribution of emphysematous change as reflected by the CAT scan and the quantitative ventilation perfusion scan with new emphasis being placed on the ventilation portion of the latter. Poor prognostic indicators are hypercarbia and pulmonary hypertension. It was felt that an algorithm could be established for determination of whether lung volume reduction or transplantation should be offered to patients for emphysema surgery. The algorithm is described.
BACKGROUND: A strategy of mechanical ventilation that limits airway pressure and tidal volume while permitting hypercapnia has been recommended for patients with the acute respiratory distress syndrome. The goal is to reduce lung injury due to overdistention. However, the efficacy of this approach has not been established. METHODS: Within 24 hours of intubation, patients at high risk for the acute respiratory distress syndrome were randomly assigned to either pressure- and volume-limited ventilation (limited-ventilation group), with the peak inspiratory pressure maintained at 30 cm of water or less and the tidal volume at 8 ml per kilogram of body weight or less, or to conventional ventilation (control group), with the peak inspiratory pressure allowed to rise as high as 50 cm of water and the tidal volume at 10 to 15 ml per kilogram. All other ventilatory variables were similar in the two groups. RESULTS: A total of 120 patients with similar clinical features underwent randomization (60 in each group). The patients in the limited-ventilation and control groups were exposed to different mean (+/-SD) tidal volumes (7.2+/-0.8 vs. 10.8+/-1.0 ml per kilogram, respectively; P<0.001) and peak inspiratory pressures (23.6+/-5.8 vs. 34.0+/-11.0 cm of water, P<0.001). Mortality was 50 percent in the limited-ventilation group and 47 percent in the control group (relative risk, 1.07; 95 percent confidence interval, 0.72 to 1.57; P=0.72). In the limited-ventilation group, permissive hypercapnia (arterial carbon dioxide tension, >50 mm Hg) was more common (52 percent vs. 28 percent, P=0.009), more marked (54.4+/-18.8 vs. 45.7+/-9.8 mm Hg, P=0.002), and more prolonged (146+/-265 vs. 25+/-22 hours, P=0.017) than in the control group. The incidence of barotrauma, the highest multiple-organ-dysfunction score, and the number of episodes of organ failure were similar in the two groups; however, the numbers of patients who required paralytic agents (23 vs. 13, P=0.05) and dialysis for renal failure (13 vs. 5, P= 0.04) were greater in the limited-ventilation group than in the control group. CONCLUSIONS: In patients at high risk for the acute respiratory distress syndrome, a strategy of mechanical ventilation that limits peak inspiratory pressure and tidal volume does not appear to reduce mortality and may increase morbidity.
OBJECTIVE: Paraesophageal hernias represent advanced degrees of sliding hiatus hernia with intrathoracic displacement of the intraesophageal junction. Gastroesophageal reflux disease occurs in most cases, resulting in acquired short esophagus, which should influence the type of repair selected. METHODS: Between 1960 and 1996, 94 patients with massive, incarcerated paraesophageal hiatus hernia were operated on at the Toronto General Hospital. The mean age was 64 years (39 to 85 years), with a female to male ratio of 1.8:1. Organoaxial volvulus was present in 50% of cases. Clinical presentation in these patients included postprandial pain in 56%, dysphagia in 48%, chronic iron deficiency anemia in 38%, and aspiration in 29%. Symptomatic reflux, either present or remote, was recorded in 83% of cases. All patients underwent endoscopy by the operating surgeon. In 91 of 94 patients, the esophagogastric junction was found to be above the diaphragmatic hiatus, denoting a sliding type of hiatus hernia. Gross, endoscopic peptic esophagitis was observed in 36% of patients: ulcerative esophagitis in 22% and peptic esophagitis with stricture in 14%. A complete preoperative esophageal motility study was obtained for 41 patients. The lower sphincter was hypotensive in 21 patients (51%), and the amplitude of peristalsis in the distal esophagus was diminished in 24 patients (59%). These abnormalities are both features of significant gastroesophageal reflux disease. In 13 recent, consecutive patients with paraesophageal hernia, the distance between the upper and lower esophageal sphincters was measured during manometry. The average distance was 15.4 +/- 2.33 cm (11 to 20 cm), which is consistent with acquired short esophagus. The normal distance is 20.4 cm +/- 1.9 (p < 0.0001). RESULTS: All 94 patients were treated surgically: 97% had a transthoracic repair with fundoplication. A gastroplasty was added in 75 cases (80%) because of clearly defined or presumed short esophagus. There were two operative deaths, and two patients were never followed up. Among the 90 available patients, the mean follow-up was 94 months; median follow-up was 72 months. Seventy-two patients (80%) are free of symptoms (excellent result); 13 (13%) have inconsequential symptoms requiring no therapy (good result); and three patients (4%) are improved but have symptoms requiring medical therapy or interval dilatation (fair result). Two patients had poor results because of recurrent hernia and severe reflux. Both were successfully treated by reoperation with the addition of gastroplasty because of acquired shortening, which was not recognized at the first operation. CONCLUSIONS: Most of these 94 patients had symptoms or endoscopic, manometric, and operative findings that were consistent with a sliding hiatus hernia. There was a high incidence of endoscopic reflux esophagitis and of acquired short esophagus. True paraesophageal hernia, with the esophagogastric junction in a normal abdominal location, appears rare. Our observations were supported by measurements obtained at preoperative endoscopy and manometry, and by findings at the time of surgical repair. These observations support the choice of a transthoracic approach for repair in most patients.
OBJECTIVE: To examine the relationship between intensive care unit (ICU) healthcare workers' confidence and their decision to withdraw life support. DESIGN: Cross-sectional survey of Canadian intensivists, ICU housestaff, and bedside nurses. Respondents chose the level of care (from comfort measures only to full aggressive care) for 12 patients described in clinical scenarios, and rated their confidence in their decisions. SETTING: Thirty-seven Canadian university-affiliated hospitals. PATIENTS: None. INTERVENTIONS: We used discrete data analysis models to examine the association between the chosen level of care, confidence in the decisions, the clinical scenario, and healthcare worker group. MEASUREMENTS AND MAIN RESULTS: The response rate was 1,361 (76%)/1,795; for this analysis, we used data from 1,306 respondents with completed questionnaires. Responses for each scenario varied widely among respondents. The level of care chosen was dependent on the scenario, the healthcare worker group, and the confidence with which the decisions were made (p < .001 for each). Intensivists were less aggressive than the ICU nurses, who were less aggressive than the housestaff, but the magnitude of effect was small. Overall, respondents were very confident about their decisions 34% of the time. After adjustment for clinical scenario and chosen level of care, intensivists were more confident than nurses, who were more confident than housestaff (40% of intensivists, 29% of nurses, and 23% of housestaff were very confident). In general, healthcare workers tended to be more confident when they chose extreme levels of care than when they chose intermediate levels of care. Considerable variability in responses to scenarios remained even when we considered only those responses made with the highest level of confidence. CONCLUSIONS: While confidence in decisions about withdrawal of life support increases with seniority and authority, consistency of decisions may not. When given standard information, healthcare workers can make contradictory decisions yet still be very confident about the level of care they would administer.
STUDY OBJECTIVE: To examine the impact of the timing of tracheotomy on the duration of mechanical ventilation, the secondary changes to the trachea, and the clinical course of critically ill patients in the ICU. DESIGN: A systematic review of the literature. METHODS: Two independent reviewers conducted a MEDLINE search for relevant literature in the form of randomized or observational controlled clinical studies. Studies were selected for review by criteria determined a priori; and the methodologic quality of selected studies was evaluated by duplicate independent review, also using criteria determined a priori. RESULTS: Five studies were identified, of which three were quasirandomized and none were blinded. Agreement between reviewers of methodologic quality was high (kappa=0.87). CONCLUSIONS: There is insufficient evidence to support that the timing of tracheotomy alters the duration of mechanical ventilation or extent of airway injury in critically ill patients.
We report our experience with 2 cases of simultaneous single-lung transplantation and lung volume reduction for emphysema. The lung volume reduction was undertaken electively in an attempt to improve overall lung function above that to be expected from single-lung transplantation alone. There were no postoperative problems related to the addition of lung volume reduction. The pulmonary function at 3 months was greater than that seen in a retrospective group of bilateral lung transplants previously reported from our institution.
The surgical management of pulmonary metastases remains controversial, as no randomized trials have compared surgical excision with nonoperative treatment (to our knowledge). A Medline-generated review of the literature was undertaken to determine the factors influencing survival following metastasectomy in published trials. In the absence of randomized comparative trials, data must remain inferential and circumstantial. However, the literature does support the anecdotal observation that patients with metastatic disease can achieve long-term survival following surgical excision, irrespective of the source of the primary neoplasm, if there is no demonstrable extrathoracic disease and complete excision of the pulmonary disease is possible. Other factors noted as influencing survival appear to be anecdotal and variable from report to report. Pulmonary metastasectomy should be considered in patients with sufficient pulmonary reserve when the lung is the only site of metastatic disease and the lesions can be totally excised. An algorithm is proposed for a logical approach to the problem.
To avoid the laborious task of investigating the cerebrovascular circulation in the midst of a trachea-innominate artery fistula, we strongly recommend preoperative cerebrovascular investigations in all patients about to undergo mediastinal tracheostomy. Paramount to this dictum remains the possibility of asymptomatic cerebrovascular disease. Inadequate preoperative cerebrovascular assessment may result in, as described in this report, the possibility of significant postoperative neurologic morbidity or mortality. Angiography should assist the surgeon in deciding which method of cerebral arterial reconstruction is best suited to the individual circumstance. We recommend the avoidance of innominate artery reconstruction even with the interposition of autologous tissues, as the operative field remains grossly infected.
BACKGROUND: Previous reports have described bronchial obstruction after left pneumonectomy (so-called post-pneumonectomy syndrome) in the presence of a right aortic arch with the bronchus being compressed between the ascending aorta and thoracic spine. This study reports on 4 patients with left postpneumonectomy syndrome in the presence of a normally located left aortic arch and ascending thoracic aorta. METHODS: The case histories of 4 patients with this syndrome were reviewed and several features common to all 4 were noted. In each case, the obstruction was thought to be due to a clockwise rotation of the mediastinum with bronchial compression occurring between the right main pulmonary artery and thoracic spine. RESULTS: Three patients were treated by repositioning of the mediastinum, and all 3 obtained relief of their dyspnea. In these cases, permanent repositioning was ensured by the insertion of a prosthesis filled with saline solution. The fourth patient was successfully treated by resection of a portion of the adjacent thoracic vertebra. CONCLUSIONS: Postpneumonectomy syndrome can occur after a left pneumonectomy in the absence of a right aortic arch. We suggest that mediastinal repositioning with a prosthesis filled with saline solution is simple, is safe, and results in complete relief of preoperative symptoms.
METHODS: We have reviewed our experience in 38 patients with adenoid cystic carcinoma of the upper airway seen between 1963 and 1995. The mean age was 44.8 years (15 to 80 years) with a male/female ratio of 1:1.1. Thirty-two of the 38 patients were treated by resection and reconstruction (primary anastomosis 28; Marlex mesh prosthesis 4). Twenty-six of the 32 patients undergoing resection received adjuvant radiotherapy. Six patients with unresectable tumors were treated primarily with radiotherapy only. RESULTS: Pathologic examination revealed local invasion beyond the wall of the trachea in all patients. In a majority, microscopic extension was found in submucosal and perineural lymphatics, well beyond the grossly visible or palpable limits of the tumor. Lymphatic metastases were relatively uncommon, occurring in only five of 32 (19%) patients undergoing resection. Metachronous hematogenous metastases occurred in 17 of 38 patients (44%). Thirteen of these 38 patients (33%) had pulmonary metastases. Sixteen of 32 resections were complete and potentially curative. There were two deaths within 30 days of operation. The mean survival in the 14 patients undergoing complete resection was 9.8 years (12 months to 29 years). Sixteen of 32 resections were incomplete (residual tumor at the airway margin on final pathologic examination), with one operative death occurring in this group. The mean survival in the 15 surviving patients was 7.5 years (4 months to 21 years). Six patients were treated with primary radiation only and had a mean survival of 6.2 years (2 months to 14.3 years). In the patients with pulmonary metastases, mean survival was 37 months (4 months to 7 years) from the time of diagnosis of the pulmonary metastasis until their death. CONCLUSION: Adenoid cystic carcinoma of the upper airway is a rare tumor, which is locally invasive and frequently amenable to resection. Although late local recurrence after resection is a feature of this tumor (up to 29 years), excellent long-term palliation is commonly achieved after both complete and incomplete resection. There was a small difference in survival between patients having complete and incomplete resection. Long periods of control can be obtained with radiotherapy alone. The best results, in this series of patients, were obtained by resection. Adjuvant radiotherapy is assumed to favorably influence survival.
BACKGROUND: Concomitant lesions of the heart and lung are uncommon, but when present they pose a therapeutic challenge for thoracic surgeons. A combined procedure avoids the need for a second major thoracic procedure and may improve outcomes and provide economic benefit. However, cardiopulmonary bypass may adversely affect the natural history of pulmonary malignancies. METHODS: The clinical records of 30 patients were reviewed who underwent simultaneous lung resection and cardiac operations between January 1982 and July 1995. Follow-up was obtained on all 30 patients (mean follow-up, 22 months; range, 1 to 100 months). RESULTS: Twenty-four patients underwent coronary artery bypass grafting in conjunction with pulmonary resection. Six patients underwent aortic (n = 4) or mitral (n = 2) valve replacement. The pulmonary resections consisted of pneumonectomy (n = 3), lobectomy (n = 14), wedge excision (n = 12), and tracheal resection (n = 1). Twenty-one patients had pathologic findings that confirmed adenocarcinoma (n = 10), squamous cell carcinoma (n = 5), small cell carcinoma (n = 2), or other malignancy (n = 4). Tumor stage of primary lung cancers was stage I, n = 12; stage II, n = 3; and stage IIIa, n = 2. Pathologic examination revealed benign disease in 9 patients. There were two operative deaths, one due to aspiration and one due to stroke. There were three late deaths, two cardiac and one of metastatic disease. Overall late survival was 85% +/- 7% and 73% +/- 16% at 1 and 5 years, respectively. Actuarial survival for patients with malignant disease was 64% at 5 years. CONCLUSIONS: Simultaneous cardiac operation and lung resection was not associated with increased early or late morbidity or mortality. Cardiopulmonary bypass does not adversely affect survival in patients with malignant disease. Cardiac valve replacement can be performed safely in conjunction with pulmonary resection.
BACKGROUND: A shortage of suitable brain-dead donors continues to severely limit lung transplantation. Use of donors with nonbeating hearts has been suggested as a solution. Lungs are unique, in that aerobic metabolism can continue in the absence of blood circulation because oxygen is present in airways and alveoli. Animal studies have shown reasonable cadaveric graft function up to several hours after sudden death by drug administration. However, hemodynamic instability before death may worsen lung function through activation and pulmonary sequestration of neutrophils and release of inflammatory mediators. Because many potential cadaveric donors experience hypotension before death, this study was undertaken to assess the effect of hypotensive shock on cadaveric lung viability. METHODS: A rat isolated lung reperfusion model was used to assess pulmonary function over 3 hours of reperfusion or until gross pulmonary edema developed. Twenty-five rats were randomly allocated to the following study groups, which were based on status before lung harvest: (1) control: no interventions; (2) hypotensive: 1 hour of hypotension by exsanguination to a mean blood pressure of 30 to 40 mm Hg; (3) cadaver: death by cervical dislocation followed by 3 hours of in situ lung ischemia; (4) hypotensive + 3 hours cadaver: 1 hour of hemorrhagic shock, followed by death and 3 hours of in situ ischemia; (5) hypotensive + 2 hours cadaver: similar to group 4, except the in situ ischemia was abbreviated to 2 hours. RESULTS: No significant differences were found among group 1, 2, or 3 lungs with regard to wet to dry weight ratios, gas exchange, and pulmonary arterial or airway pressures. However, all group 4 lungs became grossly hemorrhagic and developed severe pulmonary edema within 10 minutes of reperfusion. Group 5 lungs fared only marginally better, with two of five lungs tolerating 3 hours of reperfusion. CONCLUSIONS: A period of hypotension before death severely impairs cadaveric lung viability.
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.
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.
Chylothorax complicating pulmonary resections is exceptional and management of this complication remains controversial. We report a case of chylothorax after a right pneumonectomy and radical subcarinal nodal dissection. Successful nonoperative management consisted of controlled tube drainage, fasting, and total parenteral nutritional support for a period of 2 weeks. A review of the literature reveals 27 other cases of this complication after intrapleural pneumonectomy: 12 were treated by conservative measures alone and 15 required surgical intervention. Factors that will determine the management and the ultimate success of conservative management include (1) a relative delay in initial occurrence, (2) a decrease in or complete cessation of leakage while receiving total parenteral nutrition, and (3) favorable lymphangiographic findings.