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Biomedical subjects

A N Thomas

Publications and source records attributed to A N Thomas.

At least 55 records · Page 3Linked to original sources
PubMed1983

Management of air embolism in blunt and penetrating thoracic trauma.

The charts of 61 patients treated from 1970 through 1981 were reviewed to determine the clinical outcome after treatment of air embolism from blunt (15 patients) and penetrating (21 gunshot and 25 stabbing) thoracic injuries. The diagnosis of air embolism was confirmed by the presence of air in the coronary arteries (57%), air aspirated from the heart (30%) or major artery (10%), or Doppler findings (3%). All patients were in shock or cardiac arrest, and in 36% of these patients there were early signs of hemoptysis or unexpected arrest after intubation and positive-pressure ventilation. Successful management included (1) early thoracotomy for diagnosis as well as for specific treatment, (2) hilar cross-clamping for control of bronchovenous communication, (3) maintenance of perfusion pressures with fluids, vasopressors, or aortic cross-clamping, and (4) prompt correction of the embolic source, usually a lung resection. The overall survival rate was 44%, which correlated with the mechanism of injury, with associated nonthoracic injuries, and with the occurrence of arrest in a controlled setting. We conclude that (1) air embolism can insidiously occur even in blunt trauma; (2) suspicion should be high with hemoptysis or unexpected arrest; and (3) successful treatment includes immediate thoracotomy for diagnosis, resuscitation, and prompt control of the bronchovenous communication.

Adolescent↗
PubMed1982

Angiographic evaluation of the ductus diverticulum.

The aortic isthmus in adults has a variable appearance on thoracic aortograms. Its configuration may show a concavity, a straightening or slight convexity, or a discrete focal bulge. The latter finding represents a ductus diverticulum and, in review of 103 aortograms, was found present in 9% of patients. At times a prominent ductus diverticulum may resemble, and be mistaken for, a traumatic pseudoaneurysm of the aortic isthmus. A traumatic pseudoaneurysm may be distinguished from a ductus diverticulum on aortography by demonstration of an intimal flap and/or delayed clearance of contrast material on subtracted films. However, a ductus diverticulum will exhibit neither of these features.

Aneurysm↗
PubMed1982

Technical accuracy and clinical efficacy of thoracic computed tomography.

The technical accuracy and clinical efficacy of thoracic CAT scans in 302 surgical patients were retrospectively reviewed. We conclude that thoracic CAT scans should be ordered selectively since the technical accuracy of existing radiographic studies in detecting disease is equally high (greater than 90 percent) and the clinical efficacy does not differ substantially (less than 16 percent). The accuracy of CAT scans in staging carcinoma (the extent of the lesion or nodes) is only 58 percent. The technical limitations of these scans include (1) a lack of specificity because of the high incidence of false-positive lymph nodes, (2) a low or unreliable yield from needle aspiration, and (3) unreliable findings due to altered anatomy by previous treatment or associated disease. Surgical treatment regarding operability and resectability should not be solely based on CAT scans. These scans appear to be a useful screening test for chronic vascular disease and localization of obscure thoracic infections.

False Positive Reactions↗
PubMed1982

Pulmonary oxygen exchange during endobronchial anesthesia: effect of tidal volume and PEEP.

To determine the effects of tidal volume (VT) and positive end-expiratory pressure (PEEP) on pulmonary oxygen exchange during endobronchial (one-lung) anesthesia, the authors studied the effects of VT at 8 and 16 per cent total lung capacity (TLC), at zero end-expiratory pressure (ZEEP), and at 10 cmH2O PEEP in 16 patients in the lateral position. Anesthesia was maintained with halothane and oxygen. During two-lung ventilation (FIO2 0.99), mean PaO2 and physiologic shunt (Qs/Qt) were 421 +/- 12 mmHg and 0.22 +/- 0.02, respectively. During one-lung ventilation, PaO2 decreased and venous admixture (or Qs/Qt) increased in every patient. The magnitude of this decrease correlated directly with preoperative forced expiratory volume in one second (FEV1) (r = 0.66, P less than 0.005). A VT of 16 per cent of TLC at ZEEP resulted in the highest mean PaO2 (210 +/- 30 mmHg) and lowest Qs/Qt (0.35 +/- 0.02), probably as a result of end-inspiratory alveolar recruitment with the least pulmonary blood flow redistribution. When 10 cmH2O PEEP was applied during 16 per cent TLC ventilation, mean PaO2 decreased from 210 +/- 35 to 162 +/- 25 mmHg (P less than 0.05). PEEP did not significantly affect PaO2 during 8 per cent TLC ventilation. At both levels of VT, PEEP reduced mean Qt by approximatley 10 per cent (P less than 0.01) and increased compliance (P less than 0.01). However, PEEP did not significantly affect mean Qs/Qt or mean arterial or pulmonary arterial pressures at either level of VT. There was considerable variation in PaO2 and Qs/Qt among patients.

Adult↗
PubMed1981

Inadvertent atrial location of a sutureless epicardial pacemaker electrode.

A 70-year-old woman had an epicardial pacing system implanted after transvenous right ventricular endocardial pacing resulted in cardiac perforation. At the time of revision of the epicardial system for pacing failure, it was noted that one of the bipolar epicardial electrodes was pacing atrial tissue. The differential diagnosis of this unusual finding is discussed and recommendation urged for systematic analysis of pacing system function at the time of implant, in order to avoid inadvertent electrode placement.

Aged↗
PubMed1981

Improved survival in management of empyema thoracis.

Empyema thoracis following pneumonia, trauma, and surgical procedures continues to be a source of major morbidity and mortality. We retrospectively reviewed the hospital records of 100 patients treated for empyema thoracis at San Francisco General Hospital during the past 10 years. The causes of empyema in these patients were as follows: pneumonia 44%, trauma 24%, surgical and invasive procedures 15%, lung abscess 11%, and hematogenous spread 6%. Ten patients in this series died of sepsis from necrotizing pneumonia or overwhelming injuries caused by trauma. Streptococcus (31%), Staphylococcus (21%), and Bacteroides (15%) were the organisms most commonly isolated. Bacterial isolates were single in 55%, multiple 42%, and absent in 3%. The type of organism did not correlate with severity of disease or eventual requirement for thoracotomy, pleural débridement, or Eloesser procedure. Successful methods of treatment included aspiration in 9%, tube thoracostomy in 63%, pleural débridement and drainage in 7%, and an Eloesser procedure in 11%. Because our patients were often debilitated from chronic alcoholism, drug addiction, and major trauma, conservative management was initially tried. In most patients empyema resolved with tube thoracostomy. Pleural débridement should be reserved for patients with special problems such as multiple loculation or purulence inaccessible to percutaneous tube placement. the Eloesser procedure is indicated in patients who have an infected residual pleural space that persists despite adequate tube drainage.

Adolescent↗
PubMed1980

Unusual complications of epicardial pacemakers. Recurrent pericarditis, cardiac tamponade and pericardial constriction.

Three patients with unusual complications after insertion of an epicardial pacemaker are described. In one patient pericarditis and severe cardiac tamponade developed that required emergency pericardiocentesis 8 weeks after pacemaker insertion. No evidence of myocardial perforation was observed at operation. In another patient two unusual complications developed: (1) migration of the pulse generator from the epigastric site of implantation into the pelvis, and (2) recurrent pericarditis with occult signs of constriction. In another patient recurrent pericarditis and clinical evidence of constriction developed. All three patients required pericardiectomy. Recurrent pericarditis after insertion of an epicardial pacemaker requires careful medical follow-up because either life-threatening tamponade or chronic constrictive pericarditis may develop.

Adult↗
PubMed1980

The role of emergency room thoracotomy in trauma.

The charts of 175 patients who underwent emergency thoracotomy (ET) in the emergency room (ER) between 1972 and 1978 were reviewed to determine the efficacy of this procedure. Seven cases of nontraumatic cardiac arrest were excluded from analysis. Although 150 patients were transported to the ER within 1 hour of injury, 60% either had no vital signs (91 cases) or were agonal (20 cases) on admission to the ER. The trauma was blunt in 60 cases and penetrating in 108. The major sites of injury were heart, major vessels, head, liver, and lung. Thirty-six patients died in the ER, 83 died in the operating room, and eight of the remaining 49 patients who survived operation died acutely in the immediate postoperative period. Of the patients who survived beyond 24 hours after injury 80% recovered and left the hospital: overall 19.6% survived. If patients with irreversible head injuries are eliminated, 24% survived. Correlation of admission status with outcome revealed the following survival rates: no vital signs (6.6%); agonal (20%); profound shock (34.1%); and mild shock with subsequent deterioration (56.3%). Survival rates were higher for patients with stab wounds (40%), pericardial tamponade (38%), and injury to the heart (30%), or lungs (57%). A cost-benefit analysis revealed that total benefits were 2.4 times greater than total costs. Performing early thoracotomy in the ER is a life-saving measure for a substantial number of trauma patients who present to the ER in extremis.

Adolescent↗
PubMed1980

Management of acute cervicothoracic vascular injuries.

One hundred eighty-one patients with 218 acute cervicothoracic vascular injuries underwent operations for diagnosis, resuscitation, and control of hemorrhage. The patients were divided into three clinical groups depending on their clinical status. Group I consisted of 105 patients who were hemodynamically stable and able to undergo diagnostic measures: Group II consisted of 41 patients who remained unstable and required immediate operation; Group III consisted of 35 patients who were moribund and underwent emergency room thoracotomy. The mortality rates were 4% for Group I, 15% for Group II, and 80% for Group III with an overall mortality rate of 21%. Angiography was performed in 53% of the stable Group I patients. This allowed specific identification of lesions such as arteriovenous fistula in eight patients and aortic disruption in 12 patients. Thirty-five Group III patients had thoracotomy performed in the emergency room and seven survived (20%). A vigorous clinical approach is recommended to minimize morbidity. A different approach is described for each of the three clinical groups of patients.

Adolescent↗
PubMed1979

Extracorporeal membrane oxygenation in severe acute respiratory failure. A randomized prospective study.

Nine medical centers collaborated in a prospective randomized study to evaluate prolonged extracorporeal membrane oxygenation (ECMO) as a therapy for severe acute respiratory failure (ARF). Ninety adult patients were selected by common criteria of arterial hypoxemia and treated with either conventional mechanical ventilation (48 patients) or mechanical ventilation supplemented with partial venoarterial bypass (42 patients). Four patients in each group survived. The majority of patients suffered acute bacterial or viral pneumonia (57%). All nine patients with pulmonary embolism and six patients with posttraumatic acute respiratory failure died. The majority of patients died of progressive reduction of transpulmonary gas exchange and decreased compliance due to diffuse pulmonary inflammation, necrosis, and fibrosis. We conclude that ECMO can support respiratory gas exchange but did not increase the probability of long-term survival in patients with severe ARF.

Acute Disease↗
PubMed1978

Severe chest trauma. Morbidity implication.

Patients who sustain fracture of either the first or second rib have severe injuries usually involving multiple systems. In comparing 71 patients with first rib fractures and 49 patients with second rib fractures, we found morbidity and mortality to be similar. A multidisciplinary approach to management of these patients is described and vigorous diagnostic and therapeutic measures are warranted to promptly determine the extent of injury and minimize the frequency of missed diagnosis.

Abdominal Injuries↗
PubMed1978

Prevention of complications from prolonged tracheal intubation.

Eight commercially available soft cuff endotracheal tubes were studied to determine the relationship between inflation pressure distention of the cuff. Although the balloon cuff may be easily distensible in open air, when confined within the trachea small increments in the inflation volume may produce high pressures. This means that continuous external control of cuff pressure is required to prevent ischemia of the tracheal wall. Major tracheal complications in a busy ICU were examined before and after the introduction of a controlled pressure tube. Control of intratracheal cuff pressures decreased major tracheal complications tenfold and eliminated complications specifically related to the cuff.

Dilatation, Pathologic↗
PubMed1978

Combined treatment methods for carcinoma of the esophagus.

From 1950 to 1973, 129 patients received irradiation for esophageal squamous-cell carcinoma at the University of California, San Francisco. From this group, 26 received surgical and irradiation treatment. Twelve did not receive irradiation until recurrence became evident and among them were no 5-year survivors. Among the other 14 were six 5-year survivors (43%). The authors believe that planned sequential irradiation and surgery offer the best chance for cure in squamous-cell carcinoma of the esophagus. Selection factors, treatment details, and therapeutic regimens are presented and a management plan proposed for this group of operable patients.

Aged↗
PubMed1978

Radiofrequency-triggered pacemakers: uses and limitations. A long-term study.

Seven patients with either recurrent paroxysmal supraventricular tachycardia (five), alternatinng bradycardiatachycardia (one), or ventricular tachycardia (one) underwent insertion of permanent radiofrequency-triggered pacemakers. Follow-up evaluation (36 +/- 24 months, mean +/- SD) revealed that arrhythmias were well controlled in five of seven patients, although three of the five required medication to decrease frequency of arrhythmias. Overdrive pacing was ineffective in one patient with Wolff-Parkinson-White syndrome who had recurrent bouts of atrial fibrillation or atrial flutter. One additional patient with ventricular tachycardia became refractory to overdrive atrial pacing. These studies document the long-term effectiveness of radiofrequency pacemakers in some patients with recurrent refractory arrhythmias. Careful patient selection and electrophysiologic studies are mandatory before implantation of a permanent radiofrequency pacemaker. Physicians must be aware of both the benefits and possible limitations of radiofrequency pacemakers in order to choose between pacemaker versus surgical intervention in patients with cardiac arrhythmias refractory to standard drug therapy.

Adult↗
PubMed1978

Late sequelae of penetrating cardiac wounds.

Physiological and psychological parameters of 20 survivors of penetrating wounds of the heart were examined 7 to 52 months after recovery. All survivors had cardiac complaints. The psychological parameters for hypochondriasis, compulsiveness, and internalization were much greater in the patients than in control subjects but were similar to those in victims of violent major abdominal trauma. Physiological abnormalities were present in 19, although no particular pattern or abnormality could be related with certainty to the type of wound, operative procedure, or postoperative course. One recovered and re-employed victim required late surgical repair of a traumatic ventricular septal defect and ventricular diverticulum. Although functional work capacity measured by stress testing was normal in 90 percent, only eight survivors resumed employment. Complete rehabilitation was impaired by a residual traumatic neurosis. Management goals for patients with penetrating cardiac wounds should be broadened to include prevention of psychological disabilities.

Adult↗