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Biomedical subjects

R C Darling

Publications and source records attributed to R C Darling.

At least 163 records · Page 9Linked to original sources
PubMed1976

Leiomyosarcoma of the inferior vena cava. Diagnosis and surgical management.

Leiomyosarcoma of vascular origin are rare tumors arising most frequently from the inferior vena cava (IVC). We report on three patients one of whom underwent definitive resection. These tumors most commonly involve the upper segment of the IVC, and appear with manifestations of the Budd-Chiari syndrome. Lesions at this level are not amenable to surgical therapy. Tumors of the middle and lower segments of the IVC usually cause right-sided pain. Diagnosis is difficult, but is best approached preoperatively by angiography and vena cavography. Optimal therapy of lesions at these levels is surgical resection. Resection of the IVC below the hepatic veins is possible with renal function preserved by collateral drainage of the left renal vein.

Angiography↗
PubMed1976

Is 80 years too old for aneurysmectomy?

The records of 111 patients, 80 years of age or older, with a primary diagnosis of abdominal aortic aneurysm(AAA) showed that 86 patients underwent aneurysm resection and grafting. Ruptured AAAs (n=30) were associated with an operative mortality of 74%. By contrast, AAA resection in the expanding aneurysm group (n=19) and in the elective surgery group (n=44) was associated with a 10% and 2% mortality, respectively. Thus, resection of a nonruptured AAA in 63 octogenarians was carried out with an overall mortality of 4.7%. While nearly half of the patients had cardiac disease detected preoperatively, the elective group demonstrated a low incidence of previous myocardial infarction (7%) and congestive heart failure (8%). Concomitantly, the incidence of myocardial infarction (6%) and congestive heart failure was relatively low after AAA resection. Significant postoperative oliguric azotemia was observed in only 5% of the nonruptured patients. Long-term survival was comparable to that of the general population over the age of 80 years. The quality of life enjoyed by these patients was not adversely affected by AAA resection. By contrast, 50% of patients treated conservatively died of ruptured AAA. Physiologic rather than chronologic age should determine selection for AAA resection in the octogenarian.

Age Factors↗
PubMed1976

Sweating responses to central and peripheral heating in spinal man.

Studies of central and peripheral heating of a resting spinal man (T6) were performed under various ambient temperatures (20-34 degrees C). It was found that at a constant core temperature, sweating could not be initiated by sentient skin heating alone, but skin cooling alone did produce a rapid decrease in sweating response. Central heating alone induced sweating responses and the central temperature thresholds of sweating were inversely related to the ambient (sentient skin) temperatures. The local and mean sweating rates were found to be linearly related to the core temperature. The slopes of local sweating rates versus the core temperature vary increasingly with the following locations: chest, forearm, and forehead; but the slopes of mean sweating rates versus core temperature were essentially constant.

Adult↗
PubMed1976

Relationship between evaporation rate of sweat and mean sweating rate.

The rate of evaporation of sweat under a step change of ambient temperature (30-45 degrees C) was compared with the mean sweating rate (MSR) computed from five simultaneous resistance hygrometric measurements. Empirical equations derived for the conditions studied enabled a direct conversion from hygrometric measurements into real evaporative sweat losses and skin wetness for all phases of sweat evaporation. From five chosen skin areas, forehead, forearm, chest, thigh, and calf, it was found that none of these sites gave a local sweating response close to the MSR. In the subjects with a forehead sweating rate within +/- 39% of the MSR, at least four hygrometric sensors were needed to predict the rate of sweat evaporation. For subjects with higher forehead sweating rates, at least five sensors were necessary to calculate the evaporative sweat loss.

Adult↗
PubMed1976

Myocardial ischemia due to infrarenal aortic cross-clamping during aortic surgery in patients with severe coronary artery disease.

Hemodynamic measurements were performed and ECG recorded before and shortly after infrarenal aortic cross-clamping during operation for abdominal aortic aneurysm in five patients without evidence of heart disease (group I) and in ten patients with severe coronary artery disease (group II). All patients sustained an increase in systemic arterial pressure. Group I demonstrated a decrease in pulmonary artery, pulmonary capillary wedge (PCW), and central venous pressures when the aorta was clamped, whereas group II demonstrated an increase. The difference in response of the groups is significant (P less than 0.05). All three patients who responded to cross-clamping with increases of 7 mm Hg or greater in PCW demonstrated myocardial ischemia during cross-clamping. None of the values measured prior to cross-clamping predicted with certainty the response to cross-clamping. Sodium nitroprusside reversed the elevation of left ventricular filling pressure in all three patients, and in two patients, relieved evidence of myocardial ischemia concurrently. In the third patient, ventricular irritability was abolished by lidocaine and did not recur. We conclude that infrarenal aortic cross-clamping may cause myocardial ischemia in patients with severe coronary artery disease. This ischemia may be predicted by a rise in PCW at the time of cross-clamping, and vasodilator therapy is indicated in such patients.

Aged↗
PubMed1976

Vascular laboratory criteria for the management of peripheral vascular disease of the lower extremities.

From experience gained in over 4,500 vascular laboratory procedures, segmental Pulse Volume Recorder (PVR) tracings, systolic pressure measurements, and other noninvasive laboratory techniques have been found extremely useful in the management of patients with arteriosclerotic peripheral vascular disease. Both PVR recordings and limb pressures were found to be important and are used in complementary fashion. Although arteriography is essential in defining structural lesions and in establishing graftability, noninvasive vascular studies provide an inexpensive, accurate, reproducible method for assessing functional significance of arterial disease. These studies contribute to the diagnosis, definition of severity, and establishment of an objective baseline prior to medical or surgical therapy. Because they may be used in a repetitive manner, they are extremely useful in establishing success of a given therapy and in the long-term follow-up of patients. Based upon our experience, laboratory criteria have been developed which allow accurate identification of ischemic rest pain, aid in predicting healing of foot lesions or below-knee amputations, and quantitate the functional disability of claudication.

Amputation, Surgical↗
PubMed1976

Vascular insufficiency secondary to ergotism.

A case of ergot-induced peripheral vascular insufficiency mimicking atherosclerosis is presented and the clinical symptoms with vascular laboratory evaluation and roentgenographic findings are discussed in detail. A review of the literature of the vascular complications of ergot alkaloids is presented. After considering the various therapeutic modalities employed, a conservative, but hopefully more rational, treatment for these lesions is recommended. Although uncommon, this problem always must be considered in the differential diagnosis of the young patient, especially female, who presents with visceral or peripheral arterial insufficiency.

Adult↗
PubMed1976

Sweating responses of normal, paraplegic and anhidrotic subjects.

Dynamic sudomotor response to changing ambient temperatures (30 C to 45 C) was measured on eight unacclimatized subjects including five normals, two paraplegics and one anhidrotic patient. Mean sweating rates, computed from five simultaneously observed local rates, were used to compare the overall sudomotor response to heat exposure of the three groups. In the normal subjects, an average rise of 0.34 C in oral temperature and 2.5 C in mean skin temperature was found in a period of 65 minutes. The paraplegics developed a higher rise in both oral and skin temperatures due to a lower sweating rate in the insentinent region. (Insentient describes the sensory state of the skin below the level of the lesion where the subject has no awareness of surface stimulation). A relatively higher sweating rate was observed on the forehead and the cyclic sweating behavior of the insentient skin was not synchronous with that in the sentient. (Sentient describes the state where partial or total awareness is elicited by stimulation). The anhidrotic patient showed a twofold increase of moisture loss from the skin but no cyclic pattern of sweat gland activity on exposure to heat. In this case, hyperthermia developed with a rise in oral temperature of 1.1 C in 52 minutes versus 0.4 C rise in the controls in a period of 63 minutes.

Body Temperature↗
PubMed1976

Intraoperative autotransfusion: equipment, protocols, and guidelines.

Blood obtained by intraoperative autotransfusion is: 1) readily available 2) sterile 3) compatible 4) normothermic 5) inexpensive and may be infused rapidly for volume support. We have made extensive modifications to commercially available equipment in order to provide a safe, effective IAT. The effects of IAT in our series of 85 patients are outlined below. Red Cell Mass is reduced after IAT because of irretrievable blood loss and hemolysis, and may be controlled by homologous transfusion when necessary. Red Cell Survival is normal after IAT. Hemolysis. Plasma free hemoglobin is consistently elevated after IAT, but clears within 24 hours. Platelets are normal for patients autotransfused less than 3,500 ml; micropore filters should not be used in cases where greater than 3,500 ml blood is expected to be reinfused; in cases where greater than 3,500 ml is reinfused, 10 units of platelets are recommended for every 3,000 ml of blood reinfused; IAT does effect platelets function; however, platelets circulating within the patient function normally. Coagulation. We use local ACD to eliminate extracorporeal surface clotting. Even with massive IAT we have never demonstrated any clinical or laboratory evidence of intravascular coagulopathy. "Dilutional coagulopathy" may be procuced when greater than 5,000 ml are reinfused, and may be controlled with fresh frozen plasma and platelet concentrates. Bilirubin levels were normal after IAT despite gross hemoglobinuria. Fat emboli were not noted after IAT. Air emboli must be a concern in IAT; HOWEVER, PROPER OPERATION AND EQUIPMENT MODIFICATION MAY ELIMINATE EMBOLI. Renal Failure was not noted after IAT. Alveolar-arterial Oxygen Difference and Blood Gases were normal after IAT. We feel IAT is not necessary if a blood loss less than 1,000 ml is expected. Also, if greater than 3,500 ml is expected additional backup (i.e. homologous transfusions, platelets, fresh frozen plasma) may be required. As banked donor blood reserves become more limited, IAT may become a routine part of general surgical procedures.

Adult↗
PubMed1975

Angiography in the management of aneurysms of the abdominal aorta. Its value and safety.

The course of 190 patients with aneurysm of the abdominal aorta who underwent preoperative aortography was reviewed to determine the safety and usefulness of that procedure. There were no serious complications; minor problems occurred in only four patients and did not affect operative therapy. In 21 patients, the clinical impression of aneurysm was found to be incorrect. Surgically important findings included suprarenal extension of the aneurysm in nine patients, and demonstration of stenotic lesions in the renal arteries (37 patients) or superior mesenteric artery/celiac axis (17 patients). Helpful findings were associated aneurysms (26 patients), multiple renal arteries (28 patients), and occlusive lesions in the lower extremities or aortocranial system in 82 and eight patients respectively. Such information was found useful in planning operative procedures and minimizing operative time and blood loss. In our experience, angiography in patients with aneurysm of the abdominal aorta is both safe and informative.

Aged↗
PubMed1975

Experience with infected aneurysms of the abdominal aorta.

Seventeen consecutive patients with abdominal aortic aneurysms were treated during a 14-year period. Fever was the most common symptom first to appear (12 patients), either as fever of unknown origin or in association with other symptoms. Several factors raise the suspicion of an infected aneurysm: positive blood cultures, erosion of lumbar vertebrae, lack of aortic calcification, aneurysms found in female patients or after a prolonged illness of bacteremia. Staphylococci (41%) and Salmonella (18%) were the most common organisms. Aneurysms with Gram negative organisms exhibited a greater tendency toward early rupture than those with Gram-positive organisms (84% vs 10%), and were associated with a higher mortality. Delay in making the diagnosis adversely affected the death rate. "Infected aneurysm" is suggested as a better term than "mycotic aneurysm," since fungi are rarely involved.

Adult↗