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Biomedical subjects

G G Nicholas

Publications and source records attributed to G G Nicholas.

At least 37 records · Page 2Linked to original sources
PubMed1983

Cardiovascular monitoring during elective aortic surgery.

We designed a prospective study to determine whether cardiac ejection fraction as measured noninvasively could isolate a subset undergoing aortic surgery for whom central venous pressure (CVP) predicted pulmonary artery wedge pressure (PAWP). Sixteen patients were studied. Simultaneous values of PAWP and CVP were analyzed, using linear regression analysis. A significant correlation between CVP and PAWP was found for the entire patient population and for each of four time periods: preoperative, before and after aortic cross-clamping, during aortic cross-clamping, and postoperative. A significant correlation between PAWP and CVP was found during the entire perioperative period for 14 of the 16 patients. However, the slope of the regression line, or the sensitivity of the CVP in reflecting changes in PAWP, was greater than 0.5 in only seven of the 16 patients. There was no correlation between the preoperative ejection fraction and the CVP/PAWP. We conclude that the CVP is an insensitive indicator of left ventricular filling pressure in most patients accepted for elective infrarenal aortic surgery, and monitoring of the PAWP is recommended.

Aorta, Abdominal↗
PubMed1983

Malignant catecholamine-secreting carotid body paraganglioma.

The second known case of a malignant catecholamine-secreting (DA)-secreting carotid body paraganglioma is presented. Dopamine synthesis and secretion can be increased in malignant tumors derived from neural crest cells. Whether this is true, in addition, for extra-adrenal paragangliomas is not yet clear. Malignant paragangliomas of the carotid body and larynx, although rare, frequently have been accompanied by increased catecholamine secretion. Malignant catecholamine-secreting carotid body paragangliomas are best treated by composite resection (internal carotid artery and neck dissection), with special attention being given to measures preventing severe hypertension and arrhythmias in the perioperative period.

Adult↗
PubMed1983

Blood pressure response to exercise in children following the subclavian flap procedure for coarctation of the aorta.

Eight patients who underwent repair of coarctation of the aorta as infants (mean age 4.6 months) by the subclavian flap procedure were evaluated by dynamic exercise. Their mean age at the time of exercise testing was 4.6 years. Resting upper to lower limb systolic blood pressure gradients were similar in the patients and control subjects (mean 17 +/- 12 and 2 +/- 14 mm Hg) (p greater than 0.05). Mean resting systolic blood pressures in the upper limb were 121 +/- 10 mm Hg in the patients and 107 +/- 14 mm Hg in the volunteers (p greater than 0.05). The mean gradient between the upper and lower limbs was 13 +/- 19 mm Hg in the patients on dynamic exercise testing. No patient became pathologically hypertensive in the upper limbs during dynamic exercise. These results indicate that the subclavian flap procedure is an effective form of treatment for the symptomatic infant with coarctation of the aorta and can be expected to result in a low incidence of subclinical residual obstruction or restenosis.

Aortic Coarctation↗
PubMed1982

The treatment of severe Raynaud's phenomenon with verapamil.

Verapamil was evaluated in 16 patients with severe Raynaud's phenomenon. Fifty per cent of patients experienced subjective improvement by history, but only one patient had a substantial reduction in the frequency of Raynaud's phenomenon as assessed by diary analysis. We conclude that verapamil is not effective in most patients with severe Raynaud's phenomenon.

Clinical Trials as Topic↗
PubMed1982

The role of vascular laboratory criteria in the selection of patients for lower extremity amputation.

We evaluated clinical and vascular laboratory data on 126 patients with below-knee or forefoot amputation. Vascular laboratory examination included Doppler systolic blood pressure and arterial wave form analysis using the segmental plethysmograph. Fifty-four patients had below-knee amputation. A calf systolic pressure greater than 70 torr was associated with 97% (33/34) success (p less than 0.005), an ankle systolic pressure greater than 30 torr yielded 91% (39/43) success (p less than 0.025), and an ankle systolic pressure greater than zero yielded an 87% success (p less than 0.005). In the absence of each of the above criteria, the predictive value of a negative test was only 32%, 40%, and 52%, respectively. The presence of a popliteal pulse was associated with 97% success (p less than 0.025); however, 88% of those with an absent popliteal pulse also achieved successful healing of below-the-knee amputations. Prior vascular reconstructive surgery was detrimental to healing of below-knee amputations. with 33% failure rate (p less than 0.025). For the 72 forefoot amputations, an ankle systolic pressure greater than 70 torr yielded a 65% success (p less than 0.025). The sensitivity of an ankle systolic pressure greater than 70 torr was 80% (32/40) and an ankle systolic greater than 35 yielded a sensitivity of 95% (38/40). The specificity was low for both of these reference values. Clinical and vascular laboratory criteria can identify patients who will have a successful below-knee amputation; however, because of the high false negative rate, patients should not be denied below-knee amputation solely on the basis of Doppler systolic pressure. Vascular laboratory criteria for predicting healing of forefoot amputations are also limited by the high rate of false positive and false negative results.

Aged↗
PubMed1981

Mortality of acute renal failure after rupture of abdominal aortic aneurysms.

Acute renal failure of an abdominal aortic aneurysm is associated with an extremely poor chance of survival. We reviewed the cases of ruptured abdominal aortic aneurysm presenting between January 1, 1976 and June 1, 1979. Four patients developed oliguric acute renal failure and required hemodialysis. All patients survived despite multiple life-threatening complications. The prognosis for acute renal failure after ruptured abdominal aortic aneurysm is better than previously recognized.

Acute Kidney Injury↗
PubMed1980

Blunt cardiac trauma: the effect of alcohol on survival and metabolic function.

Cardiac mitochondria showed significant uncoupling of oxidative phosphorylation after rats were given intraperitoneal alcohol. The rate of oxygen utilization in the absence of ADP was increased while there was no significant change in oxygen utilization in the presence of ADP. These in vivo results were confirmed with in vitro experiments. Also, intraperitoneal alcohol increased the mortality of blunt cardiac trauma. The alterations in cardiac energy metabolism demonstrated may explain the increased mortality in alcohol-pretreated animals subjected to cardiac contusion.

Animals↗
PubMed1979

Femoropopliteal bypass grafting: predictive value of preoperative angiography.

Our experience with femoropopliteal grafting was reviewed to determine whether quantitative grading of the preoperative angiogram could be correlated with the outcome of the grafting procedure. The series consisted of 53 bypass grafts in 50 patients. The quantitative grading of the preoperative arteriogram correlated with the graft closure rate during the follow-up period of 48 months. The group with the most advanced arterial occlusive disease on angiography had a 32 per cent failure rate, while those with the least severe disease had a 6.7 per cent failure rate. The intermediate group had a 16.7 per cent closure rate. Using linear regression analysis, the data indicated a correlation between the time of graft failure in the first 18 months and the angiographic grade (p less than 0.01).

Angiography↗
PubMed1979

Traumatic renal arteriovenous fistula: case report and useful operative technique.

A patient with a traumatic extrarenal arteriovenous fistula underwent successful repair of the lesion. The reconstruction utilized a portion of renal vein to allow lateral repair of the renal artery. The patient's postoperative course was complicated by paradoxical hypertension and severe abdominal pain like that in the "post-coarctectomy syndrome." Satisfactory recovery has occurred and the patient remains normotensive.

Abdominal Injuries↗
PubMed1978

Buckshot wounds.

The differences between wounds due to conventional shotgun (shot) injuries and those inflicted by buckshot are inadequately appreciated by most clinicians. Cadaver extremities were used as targets for 12-gauge loads of No. 6 shot and 00 Buckshot to portray some of the "wounding" characteristics of these popular shotgun loads. "Wounds" so produced were consistent with expected ballistic performance of these projectiles. The lethality of buckshot wounds is discussed, four clinical cases are described, and the wounding mechanisms are briefly outlined.

Adolescent↗
PubMed1977

Clinical vascular laboratory diagnosis of deep venous thrombosis.

The accuracy of our clinical vascualr laboratory was evaluated. Sixty-nine limbs (55 patients) were examined clinically for thrombophlebitis. All of these patients were then evaluated using segmental plethysmography and Doppler ultrasound techniques. Each limb was then studied with venography. In 57 of the 69 (82.6%) limbs evaluated, measurement of the maximum venous outflow accurately reflected the venographic findings. Doppler augmented venous sounds were correct when compared to venography in 77.6% of limbs. In the 59 limbs that exhibited clinical signs of deep venous thrombosis, only 35.6% had venographic confirmation of the diagnosis. The clinical vascular laboratory provides an accuracy of diagnosis of deep venous thrombosis not achieved by clinical examination. If both segmental plethysmography and Doppler ultrasound were negative, it was very unlikely that deep venous thrombosis had occurred.

Doppler Effect↗