Biomedical subjects
Publications and source records attributed to T R McLean.
The author traveled to Puerto Rico and arranged to visit several hospitals as an ambassador for ASPAN. In this article, he describes what he saw and explains the similiarities in nursing care between two cultures.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Limitations of myocardial cooling using antegrade infusion cardioplegia have led to the routine use of topical myocardial cooling. However, topical myocardial cooling can injure the phrenic nerves, lungs and heart. Red blood cells are also discarded with the irrigation fluid. To evaluate the selective use of topical cooling, data were collected prospectively from 67 consecutive patients undergoing isolated coronary artery bypass operation. All patients received an inductive dose of 1 liter blood cardioplegia solution. Intramyocardial temperatures were determined in the distribution of the three major coronary arteries after the first 500 ml of cardioplegia solution was administered. If the three temperature readings were all < or = 20 degrees C, patients (group 1, n = 31) received no topical myocardial cooling. If any temperature was > 20 degrees C, patients (group 2, n = 36) received topical cooling while the second 500 ml cardioplegia solution was administered. Cardioplegia solution was subsequently administered at approximately 20-min intervals, at which time the patient did or did not receive topical myocardial cooling, depending on the selected group. Although patients in group 2 were older (mean (s.e.m.) age 63.3(1.6) versus 56.8(1.8) years, P < 0.05), the two groups were not significantly different with respect to sex, ejection fraction, risk factors, and class of the New York Heart Association. There were also no significant differences in the mean number of grafts per patient, use of the internal mammary artery, and cross-clamp or pump times. There were no deaths and only one patient (3%) in group 2 developed new Q waves.(ABSTRACT TRUNCATED AT 250 WORDS)
Postlaparotomy patients who remain in the Surgical Intensive Care Unit (SICU) are frequently suspected of harboring an intra-abdominal abscess (IAA). Computed Tomography (CT) of the abdomen has been advanced as an accurate method to diagnose an IAA. To determine the clinical parameters predictive of CT scan results, and the survival of such patients, this study reviewed a consecutive series of 29 postlaparotomy patients who were evaluated by abdominal CT scan while in the SICU. An IAA was identified significantly more frequently by CT when patients were explored for a GI malignancy (70% vs 30%; P < 0.05) and when patients were operated upon electively (11.1% vs 20.0%; P < 0.05). Postoperatively, alert patients were significantly more likely to have a CT scan positive for an IAA than were patients who were lethargic or nonresponsive (90% vs 10%; P < 0.05). Laboratory data, including radiographic studies, were not predictive of the CT scan results. A negative CT scan modified therapy in only 10.5 per cent of patients, while a positive scan altered therapy in 70 per cent of patients (P < 0.05). The overall survival for this group was 48.1 per cent. The identification of an IAA by CT scan did not significantly improve survival (42% with an IAA vs 40% without an IAA). APACHY II scores were significantly increased in nonsurvivors (17.4 +/- 6.0 survivors vs 23.76 +/- 7.8 nonsurvivors; P < 0.05). Our data indicate that in critically ill postlaparotomy SICU patients who were evaluated by abdominal CT scanning, there are some clinical clues that tend to predict whether or not CT scanning will identify an IAA.(ABSTRACT TRUNCATED AT 250 WORDS)
Postoperative intra-abdominal abscess (IAA) is a dreaded surgical complication. Percutaneous drainage (PD) has been offered as an alternative to surgical drainage for IAA because of the perceived lower morbidity and mortality rates. Seventeen consecutive unselected instances of IAA were reviewed to determine the value of the routine use of PD. Two patients with obvious anastomotic dehiscence and one with a retroperitoneal abscess were believed to be inappropriate for PD. Patients who could be managed by PD (group 1, n = 6) were similar to patients undergoing PD plus surgical drainage (group 2, n = 8) with respect to age, initial procedure, interval from operation to diagnosis of IAA and extent of organ failure. However, in group 2, more abscesses were greater than 5 centimeters (16.7 versus 62.5 percent), associated with polymicrobial growth (0.0 versus 50.0 percent), associated with enteric organisms (16.7 versus 100 percent; p < 0.05), accompanied by anastomotic dehiscence (16.7 versus 62.50 percent) and followed by a greater degree of mortality (16.7 versus 50 percent). Overall, only 33 percent of IAA were successful managed with PD alone. We conclude from these data that PD is of value only in selected instances of IAA. If an anastomotic dehiscence is a possibility, the patient should be managed operatively.
Objective data on the ability of cineangiography to predict the size of reconstituted totally occluded coronary arteries, as well as the clinical outcome of such revascularization, are sparse. Accordingly, we reviewed 200 consecutive cases of coronary revascularization to determine the answers to these questions. Group I patients (n = 57, with 86 totally occluded coronary arteries) had at least one coronary artery with a 100% proximal occlusion that reconstituted distally. Group II patients (n = 143, with 205 subtotally occluded coronary arteries) had 50% to 99% proximal stenosis of at least one coronary artery. Cineangiograms were blindly reviewed to measure the size of the coronary arteries, which were compared with the actual vessel size at operation. In group I, the totally occluded coronary arteries had a cineangiographic size of 1.9 +/- 0.7 mm and an actual size of 1.6 +/- 0.4 mm (p = 0.00004). In group II, the subtotally occluded coronary arteries had a cineangiographic size of 1.8 +/- 0.4 mm compared with an actual size of 1.8 +/- 0.3 mm (p = not significant). The site of bypass grafting was significantly smaller in group I (1.6 +/- 0.4 mm versus 1.8 +/- 0.3 mm; p = 0.00008). The two groups were similar with respect to preoperative and intraoperative parameters. Operative mortalities were similar (group I, 1.8%; group II, 3.5%; p = 0.68). Creatine kinase isoenzyme profiles and electrocardiographic changes were similar, except for a significant late rise of creatine kinase-MB in group I (56.1 +/- 14.7 versus 30.7 +/- 33.7 MIU/mL; p < 0.001). In conclusion, cineangiography significantly overestimates the size of totally occluded coronary arteries.(ABSTRACT TRUNCATED AT 250 WORDS)
Early diagnosis of postoperative cardiac tamponade is impeded by its clinical similarity to left ventricular failure. Moreover, the hemodynamic changes necessary to diagnose cardiac tamponade are detected by conventional monitoring technique only after clinical compromise. Early signs of cardiac tamponade and left ventricular failure were studied with emphasis on right ventricular function in anesthetized dogs. One group (n = 20) had cardiac tamponade produced by incrementally increasing pericardial pressure (2 to 20 mm Hg), and another group (n = 20) had acute left ventricular failure produced by successive ligation of the anterior descending coronary artery at the lower, middle, and upper thirds. Besides standard hemodynamic measurements, right ventricular function was examined with a rapid-response thermodilution catheter. During cardiac tamponade, cardiac output, right ventricular ejection fraction, right ventricular stroke volume, and right ventricular end-diastolic volume were significantly decreased from baseline values after a pericardial pressure of 8 mm Hg or more (p less than 0.05). Right atrial and pulmonary arterial pressures were not significantly elevated until 14 and 20 mm Hg of pericardial pressure, respectively. Although cardiac function in the left ventricular failure group was reduced after each ligation, right ventricular ejection fraction remained unchanged. This study suggests that right ventricular indices may facilitate earlier diagnosis of cardiac tamponade with greater accuracy.
Similar to other methods of organ preservation, "spinoplegia" may protect the spinal cord from the effects of oxygen desaturation during aortic cross-clamping. In porcine experiments, spinal cord O2 saturation was studied during intraoperative localization of the blood supply to the spinal cord using hydrogen; division of arteries not supplying the spinal cord; aortic cross-clamping for 60 minutes; and 60 minutes after unclamping. In 5 animals, 120 mL of cold saline solution with lidocaine (100 mg/dL) was infused into the aorta during aortic cross-clamping. During sequential localization, O2 saturation dropped by 40.02% (standard deviation, 20.16%) for T-14 artery testing versus a decrease of 17.27% (standard deviation, 11.88%; p = 0.0075) for L-5 artery segment testing in the control animals and returned to baseline thereafter. During aortic cross-clamping maximal O2 desaturation was 5% of baseline (15.7%; p less than 0.0001), which improved slightly by 30 minutes after clamping (48% of baseline +/- 37.37%; p = 0.048 versus maximum) and then returned to baseline (97.1% of baseline +/- 41%) with unclamping; 5 minutes later, hyperoxygenation occurred with a progressive decline thereafter (68% of baseline +/- 29.3%; p = 0.025, 45 minutes after unclamping versus baseline). The decrease in spinal motor evoked potentials was significantly less (p less than 0.02) in the treated group. Intraoperative hydrogen testing in 8 patients was demonstrated to be safe. It accurately localized reattached arteries, and O2 saturation of the spinal cord fell by 56% (standard deviation, 29%; p = 0.0025) with aortic cross-clamping. We conclude that spinal cord ischemia occurs with aortic cross-clamping in both animals and humans.(ABSTRACT TRUNCATED AT 250 WORDS)
Conventional blood conservation techniques have been insufficient to decrease transfusion needs in increasingly complex cardiac operations. To evaluate combinations of conservation techniques, 300 patients were divided into three equal groups. Group 1 had intraoperative autotransfusion and return of mediastinal drainage for 4 hours postoperatively. Group 2 had these measures plus intraoperative plasmapheresis. These two groups were given a transfusion for a hematocrit of less than 0.21 on cardiopulmonary bypass. Group 3 was treated with the same measures as group 2 but did not receive transfusions while on pump unless the hematocrit decreased to less than 0.15. The percentage of patients in each group given transfusions in the operating room was 34% in group 1, 28% in group 2, and 7% in group 3 (p less than 0.05). The percentage of all patients receiving transfusions during hospitalization was 68% in group 1, 36% in group 2 (p less than 0.05), and 18% in group 3 (p less than 0.05). Average total units transfused were 2.16 +/- 0.25 in group 1, 0.7 +/- 0.15 in group 2 (p less than 0.05), and 0.37 +/- 0.07 in group 3 (p less than 0.05). The perioperative morbidity rates including myocardial infarctions and strokes were similar. There were no deaths in group 3. Combining complementary conservation measures is effective in reducing homologous blood transfusions, and the need for transfusion can be safely reduced by allowing profound hemodilution during bypass.
Penetrating trauma involving the innominate artery is uncommon. Few surgeons have experience with this injury. A successfully managed case of penetrating innominate artery trauma is summarized and the literature reviewed.
Massive hemoptysis due to broncholithiasis is rare. Such a case is presented here, and the literature is reviewed. Surgical resection is the preferred definitive therapy, as a lack of bronchial artery collaterals limits the utility of bronchial artery embolization.
Computed tomography is used with increasing frequency to evaluate blunt chest trauma. Since traumatic aortic rupture (TAR) is a rapidly lethal condition, unnecessary CT scanning may not be justified. To determine the accuracy of chest CT scanning for TAR, we reviewed 17 patients who underwent both chest CT scanning and aortography. Five patients had TAR by aortography. CT scanning yielded three true positives and two false negatives. In 12 patients with a negative aortogram, CT scanning recorded four false positives and eight true negatives. The specificity was 23% and the sensitivity was 83% compared with aortography. The overall accuracy for CT scanning was 53%. From these data we conclude that in the presence of an unstable patient or where there is a strong clinical suspicion of TAR the patient should proceed directly to aortography.
Metastatic involvement of the mediastinum by liposarcoma is uncommon, and clinical experience in its management is limited. A patient with liposarcoma of the lower extremity having a concomitant anterior mediastinal mass as the only manifestation of distant metastatic involvement is described.
Although an absolute correlation has been impossible to demonstrate, it has long been thought that the manometric magnitude of the lower esophageal sphincter pressure was a good index of lower esophageal sphincter strength, and hence its competence. To study this relationship, 12 adult mongrel cats were surgically fitted with gastric cannulas. The cats were studied by six-lumen, radially-oriented, rapid pullback manometry before and after administration of atropine, and before and after daily perfusion of the distal esophagus with 0.1 N hydrochloric acid. Lower esophageal sphincter strength was determined by the lower esophageal sphincter pressure vector cross-sectional area. This was computed by plotting the lower esophageal sphincter pressure on polar coordinates, and finding the area circumscribed by the vectors. Lower esophageal sphincter competence was determined by measurement of both the intragastric volume and intragastric pressure required to produce gross reflux. Atropine significantly decreased the mean lower esophageal sphincter pressure vector cross-sectional area from 7,963 +/- 2,469 mm Hg to 720 +/- 59 mm Hg (p less than 0.05) and decreased the mean lower esophageal sphincter opening pressure from 30.2 +/- 6.9 mm Hg to 13.2 +/- 4.1 mm Hg (p less than 0.05). However, acid perfusion significantly decreased the lower esophageal sphincter pressure vector cross-sectional area from 6,786 +/- 3,334 mm Hg to 715 +/- 720 mm Hg (p less than 0.05). This indicates that the lower esophageal sphincter has two components, one of which is acid-sensitive and both of which are atropine-sensitive.
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