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Biomedical subjects

W C Shoemaker

Publications and source records attributed to W C Shoemaker.

At least 91 records · Page 5Linked to original sources
PubMed1990

Intestinal perforation due to cytomegalovirus infection in patients with AIDS.

Intestinal perforation due to cytomegalovirus (CMV) infection in patients with AIDS is the most common life-threatening condition requiring emergency celiotomy in these patients. The authors describe a patient with AIDS with intestinal perforation due to CMV infection, and review 14 additional cases reported in the English-language surgical literature. The diagnostic triad of pneumoperitoneum on x-ray, evidence or history of CMV infection, and AIDS occurred in 70 percent of patients. The most common site of intestinal perforation was the colon (53 percent), followed in frequency by the distal ileum (40 percent) and appendix (7 percent); perforation usually occurred between the distal ileum and splenic flexure of the colon. Colonoscopy, rather than sigmoidoscopy, is recommended as a screening examination in patients with AIDS suspected of having colonic ulceration due to CMV infection. Multiple biopsies of ulcerated tissue should be obtained. Gross and microscopic analyses of involved intestinal tissue reveal the characteristic findings of ulceration and CMV infection. Despite aggressive therapy, the operative mortality rate in patients with AIDS with intestinal perforation due to CMV infection was 54 percent and the overall mortality rate was 87 percent. Postoperative complications occurred in most patients and consisted mainly of systemic sepsis and pneumonia caused by Pneumocystis carinii infection. An increased awareness of this syndrome by physicians frequently called on to manage patients with AIDS is recommended.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Comparison of cardiorespiratory responses to sudden progressive hypoxia in an animal model with and without respiratory failure.

The aim of this study was to compare the hemodynamic and oxygen transport responses to sudden, acute progressive hypoxia in normal control conditions (six healthy dogs) and in subacute respiratory failure (six dogs with naturally occurring distemper). The latter were used to simulate respiratory failure from viral pneumonitis in man. Acute progressive hypoxia was induced by rebreathing through a respirometer while hemodynamic and oxygen transport variables were rapidly and repeatedly measured. The immediate effects of hypoxia were decreased PaO2 and oxygen delivery. In the middle period of hypoxia, defined as periods 4, 5, and 6 of eight equally spaced time periods, cardiac index, stroke volume, and oxygen extraction increased; these occurred as compensatory responses. Oxygen consumption (VO2) remained relatively stable until late in both control and distemper dogs. Initially, physiologic compensations in distemper dogs were found to be partially exhausted and overall to be shorter in duration and of lesser magnitude when compared with the healthy control animals. Failure to maintain near normal VO2 toward the end of the hypoxic episode indicated the progression of decompensation, imminent circulatory deterioration, and death.

Acute Disease↗
PubMed1990

Techniques of splenic preservation using fibrin glue.

Fibrin glue (FG) was used to achieve hemostasis of 16 splenic injuries in 14 patients. The etiologies of injury included five gunshot wounds, two stab wounds, four iatrogenic injuries, and five patients with blunt splenic trauma. The intraoperative blood loss averaged 1.8 +/- 2.4 (SD) liters and patients were transfused 3 +/- 2 units of blood perioperatively. The amount of FG required to achieve splenic hemostasis averaged 11 +/- 8 ml and varied directly with the grade of injury. One patient with a splenic hilar vascular injury (Grade V) underwent splenectomy following failure to achieve complete hemostasis despite the use of 25 ml of FG. All other splenic injuries were successfully managed using less than 25 ml of FG. Postoperative computerized tomographic (CT) scanning, performed in ten patients, was negative for rebleeding or abscess formation. The overall splenic salvage rate was 86%. FG was effective in achieving hemostasis of both superficial and deep splenic injuries. Its use as an adjunct in trauma surgery should result in increased splenic salvage rates compared with that obtained using conventional surgical techniques.

Adult↗
PubMed1990

What should be monitored? The past, present, and future of physiological monitoring.

The status of conventional monitoring by vital signs and present concepts of invasive monitoring with the balloon-tipped pulmonary artery (Swan-Ganz) catheter are reviewed. Survivors of high-risk general surgery were observed to have cardiac index (CI) values averaging 4.5 L/min.m2, oxygen delivery (DO2) greater than 600 mL/min.m2, and oxygen consumption (VO2) greater than 170 mL/min.m2. By contrast, those who subsequently died during their hospitalization maintained relatively normal CI, DO2, and VO2 values. However, in the immediate postoperative period, values for other hemodynamic variables were not greatly different for survivors and nonsurvivors or different from the normal range. A predictive index based on these observations predicted outcome correctly in 94% of the subjects in a subsequent prospective study. The use of survivor values as appropriate therapeutic goals was tested in prospective randomized clinical trials and was found to reduce mortality and morbidity significantly. Simultaneous invasive and noninvasive hemodynamic and oxygen-transport monitoring systems were evaluated in high-risk postoperative patients to describe unanticipated adverse circulatory events. Before the monitored event, about three-fourths of the patients exhibited normal function. At the nadir, cardiac functions decreased in about two-thirds, perfusion decreased in more than one-half, and paO2 fell in only one-fourth. Two-thirds recovered with increased cardiac function, more than one-half had improved perfusion, and paO2 increased in fewer than one-fifth of monitored events. These data provide an information base for criteria needed to develop therapeutic decision rules for noninvasive monitoring systems. When noninvasive data are continuously displayed early in the course of critical illness and high-risk conditions, therapy may be instituted early, while physiological deficits are still minimal and easily reversible.

Critical Care↗
PubMed1990

Therapy of shock based on pathophysiology, monitoring, and outcome prediction.

High-risk patients who survived general (noncardiac) surgery were observed to have cardiac index (CI) values averaging 4.5 L/min.m2, oxygen delivery (DO2) greater than 600 ml/min.m2, and oxygen consumption (VO2) 170 ml/min.m2 during the first 2 or three days postoperatively. Patients who subsequently died maintained relatively normal CI, DO2, and VO2 values in this period. Values of other variables in survivors and nonsurvivors were not appreciably different. An index based on these observations correctly predicted outcome in 94% in a subsequent prospective study. Two hypotheses: a) that increased flow and oxygen transport represent compensatory physiologic responses to an earlier tissue oxygen debt, and b) that these survivors' values were appropriate therapeutic goals, were tested in prospective randomized clinical trials. The protocol group attained those therapeutic goals. This resulted in significantly reduced mortality and morbidity. Optimal goals were more easily attained with colloids, red cells, and an inotropic agent, dobutamine. Dobutamine was used because, in a prospective crossover clinical trial with dopamine at various doses, dobutamine produced greater increases in flow and flow-related variables. More importantly, it improved tissue perfusion as reflected by greater increases in VO2 and greater reductions in pulmonary and systemic vascular resistance.

Blood Volume↗
PubMed1989

Fibrin glue achieves hemostasis in patients with coagulation disorders.

Fibrin glue (FG), made with highly concentrated human fibrinogen and clotting factors, was used to achieve parenchymal organ hemostasis in patients with disordered coagulation secondary to massive transfusion, chronic disease, and disseminated intravascular coagulation; it was effective in controlling liver hemorrhage in seven patients and in the performance of a splenorrhaphy in one other patient. The coagulation profile was grossly abnormal in all patients, and the mean +/- SD intraoperative blood loss was 5.1 +/- 4.2 L; patients received 14 +/- 10 U of blood perioperatively. The amount of FG required to achieve hemostasis varied directly with the extent of injury and intraoperative blood loss (r = .84), and all patients with a blood loss greater than 4 L required at least 25 mL of FG to stop bleeding. Two patients died postoperatively secondary to cardiac arrest and adult respiratory distress syndrome. Because FG does not depend on adequate platelet or clotting factor levels to be effective, it is especially useful in patients with parenchymal organ hemorrhage and disordered coagulation.

Adult↗
PubMed1989

Prediction of below-knee amputation wound healing using noninvasive laser Doppler velocimetry.

Preoperative laser Doppler velocimetry (LDV) measurements of calf and brachial skin perfusion were performed in 29 patients prior to undergoing below-knee amputation; dual calf measurements on the anterior and posterior skin flaps were routinely obtained. Patients' ages ranged from 24 to 83 years; 16 had diabetes, 13 were smokers, 6 had hypertension, and 2 had known coronary artery disease. Anterior and posterior calf LDV values greater than or equal to 20 mV were associated with successful below-knee amputation wound healing in 25 of 26 patients; all 3 patients with either anterior or posterior calf LDV values less than 20 mV had below-knee amputations that failed to heal. Calculation of calf-brachial LDV indexes did not increase predictive accuracy compared to calf LDV measurements alone, although patients with wounds that failed to heal tended to have lower calf-brachial indexes. Preoperative noninvasive LDV may be used to aid in predicting the likelihood of successful healing after below-knee amputation.

Adult↗
PubMed1989

Diagnosis of traumatic thoracic aortic rupture: a 10-year retrospective analysis.

A 10-year retrospective analysis of 82 patients with suspected thoracic aortic rupture (TAR) due to blunt chest trauma was performed to define which symptoms and signs were helpful in making an early diagnosis. Symptoms and signs associated with TAR included midscapular back pain (in the absence of thoracic spine fracture), unexplained hypotension, upper extremity hypertension, bilateral femoral pulse deficits, and initial chest tube output in excess of 750 mL. Chest roentgenographic signs seen with significantly greater frequency in the 12 patients with TAR than in 70 patients without such rupture included a widened paratracheal stripe (7 patients), deviation of the nasogastric tube or central venous pressure line (5 patients), blurring of the aortic knob (9 patients), abnormal paraspinous stripe (6 patients), and rightward tracheal deviation (5 patients). Mediastinal widening of greater than 8 cm occurred in 11 of the 12 patients with TAR (sensitivity, 92%); its specificity, however, was only 10% (11 true-positive and 63 false-positive results). In patients in hemodynamically stable condition who display these findings, immediate aortography should be considered. The presence of myocardial contusions, intraabdominal injuries, and pelvic fractures also occurred more frequently in patients with TAR. We conclude that a detailed history, physical examination, and chest roentgenography, with rapid progression to aortography in suspicious cases, represent the safest and most reliable approach to patients with TAR.

Accidents, Traffic↗
PubMed1989

Fibrin glue in renal and ureteral trauma.

Fibrin glue (FG) made with highly concentrated human fibrinogen and clotting factors was used to achieve hemostasis of fourteen renal injuries and to seal three ureteral anastomoses in 15 patients. The cause of injury included twelve gunshot wounds, four stab wounds, and one iatrogenic ureteral injury. The mean intraoperative blood loss was 1.6 +/- 1.1 L (SD), and patients received 4 +/- 5 units of blood perioperatively. Utilizing the described techniques, FG was effective in achieving hemostasis and sealing ureteral suture lines against leakage in all cases. There were no cases of renal infection, rebleeding, urinary fistulas, delayed rupture, stone formation, or urinary tract obstruction. Two patients underwent re-exploration for causes unrelated to their renal or ureteral injuries. The use of FG was associated with less reliance on suture redundancy to achieve parenchymal hemostasis and perform ureteral anastomoses. FG sealing of renal and ureteral injuries is a safe and effective technique for controlling hemorrhage and sealing anastomoses. It is effective in the management of both superficial and deep renal injuries.

Adolescent↗
PubMed1989

Testicular oximetry: a new method for the assessment of tissue perfusion and viability following torsion and detorsion.

This study evaluated the use of a polarographic surface PO2 electrode to assess testicular perfusion and viability following torsion and detorsion. Adult male Sprague-Dawley rats were divided into groups and subjected to unilateral testicular torsion and detorsion of varying degrees and durations. Rats subjected to sham torsion or 720 degrees torsion did not show significant decreases in testicular PO2 after 15 minutes, whereas those subjected to 1,080 degrees torsion or spermatic cord ligation uniformly decreased their testicular PO2 to 0 mm Hg within 10 minutes. Testicular PO2 values were similar in rats subjected to 60 minutes of 720 degrees torsion followed by detorsion and those undergoing 15 minutes of 1,080 degrees torsion and detorsion. Rats subjected to breathing 100% oxygen uniformly increased their testicular PO2 to an average of more than twice room-air values. However, rats subjected to 1,080 degrees torsion for 6 hours followed by detorsion did not increase their testicular PO2 when subjected to breathing 100% oxygen, whereas those subjected to 720 degrees torsion for 6 hours followed by detorsion did increase their testicular PO2 when subjected to breathing 100% oxygen. The latter rats did not show microscopic changes associated with acute testicular infarction, whereas the former did.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1989

Multisensor transcutaneous oximetric mapping to predict below-knee amputation wound healing: use of a critical Po2.

Preoperative transcutaneous oxygen tension (tcPo2) measurements of calf and brachial skin were performed on 40 patients before they underwent below-knee amputation (BKA); dual calf measurements on the anterior and posterior skin were obtained. Both anterior and posterior calf tcPo2 values were significantly lower in patients with unsuccessful wound healing after BKA compared to those with successful healing (p less than 0.01). Successful wound healing occurred in 50% (6/12) of patients with calf tcPo2 values less than 20 torr and in 96% (27/28) of patients with calf tcPo2 values greater than 20 torr. Calculation of a critical Po2 index (defined as the lesser of the anterior and posterior calf/brachial tcPo2 ratios) resulted in improved predictive accuracy; 100% (6/6) of patients with a critical Po2 index of 0.20 or less had unsuccessful wound healing after BKA, whereas 97% (33/34) of patients with a critical Po2 index greater than 0.20 had successful healing. The use of a critical Po2 index greater than 0.20 as predictive of successful healing after BKA was associated with a sensitivity, specificity, and overall accuracy of 100%, 86%, and 98%, respectively, compared to 82%, 86%, and 83%, respectively, by use of absolute calf tcPo2 values. In conclusion, multisensor transcutaneous oximetric mapping is an accurate method for predicting wound healing success after BKA. Measurement of both anterior and posterior calf tcPo2 should be performed; calf tcPo2 values less than 20 torr may indicate local ischemia, but ischemia should be confirmed by comparison of calf tcPo2 with brachial tcPo2 before the patient is denied BKA.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Incidence, physiologic description, compensatory mechanisms, and therapeutic implications of monitored events.

We described 663 unanticipated monitored circulatory events in 247 high-risk surgical patients by simultaneous invasive and noninvasive hemodynamic and oxygen transport monitoring systems. Unanticipated monitored events were defined as sudden reductions (greater than 20%) in cardiac index (CI), PaO2, SaO2, transcutaneous PO2 (PtcO2), and PtcO2/PaO2 index, or decreases to the lower limits of satisfactory values, specifically: PaO2 less than 70 torr, SaO2 less than 95%, PtcO2 less than 50 torr, and PtcO2/PaO2 less than 0.6. Essentially, monitored events are the small variations superimposed on the overall physiologic patterns that describe the entire course of critical illnesses. Monitored events are described by their baseline values just before each event, at the nadir of the event, and at the recovery from the event. To simplify presentation of complex changes in many variables, the circulatory changes were evaluated in terms of cardiac, pulmonary, and peripheral perfusion functions. Common patterns of these monitored events and the incidence of these patterns in high-risk surgical patients were described. Before the unanticipated monitored event, there were normal or increased heart, lung, and perfusion functions in about three fourths of the events. At the nadir, cardiac functions decreased in about two thirds, perfusion decreased in over half, and lung function fell in only one quarter of the events. Recovery occurred with increased cardiac function in two thirds, improved perfusion in over half, and increased lung function in less than one fifth of these monitored events. Noninvasive and invasive hemodynamic and oxygen transport variables were measured simultaneously to evaluate compensatory and decompensatory patterns.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Gas Analysis↗
PubMed1989

Comparison of hemodynamic and oxygen transport effects of dopamine and dobutamine in critically ill surgical patients.

Hemodynamic and oxygen transport effects of dopamine and dobutamine were studied in a series of 25 critically ill postoperative general surgical patients by a prospective, randomized crossover design after maximal response to fluids had been obtained. Dopamine increased MAP, HR, CI, PvO2, DO2, and Qsp while decreasing PaO2. Dobutamine increased HR, CI, SI, stroke work, DO2, VO2, and Qsp while decreasing PAWP and SVRI and PVRI. In general, the effects of the two drugs were greater in patients in the first 72 hours after surgery. The effects of dobutamine on flow and oxygen transport were greater than those of dopamine, especially in the early postoperative period. The effects were smaller and not significant in patients more than three days after surgery, as well as in those with sepsis, respiratory failure, renal failure, age over 65 years, and hyperdynamic states, in part because of the small number of patients in each group. These data are consistent with the hypothesis that the beta 2-adrenergic action of dobutamine vasodilates the previously constricted peripheral circulation, enhances tissue perfusion by improving micro-circulatory flow distribution, and improves DO2 and VO2.

Adult↗