Biomedical subjects

F E Pollock

Publications and source records attributed to F E Pollock.

11 recordsLinked to original sources

PubMed1995

The microcirculatory effects of peripheral sympathectomy.

Microvascular physiology following peripheral artery sympathectomy was evaluated in seven hands with refractory pain (n = 7) and ulceration (n = 7) by serial isolated cold stress testing, which measures digital temperature and cutaneous perfusion (laser Doppler fluxmetry). All patients (n = 6) had vasospasm (secondary Raynaud's phenomenon) and arteriographically proven digital and palmar occlusive disease. Microcirculatory flow responses were correlated with symptoms and signs (including ulcer healing) before and after (2-8 weeks, 12-15 weeks, and 24 weeks) peripheral sympathectomy. Baseline data were compared with those of controls (n = 7 extremities). Following surgery, all seven hands had diminished pain; six had ulcer healing and one had ulcer reduction. Isolated cold stress testing demonstrated abnormalities in temperature and laser Doppler fluxmetry response between patients and controls. Although total flow (reflected by temperature) was not significantly increased after surgery, peripheral sympathectomy increased nutritional flow in these patients with combined vasospastic vessels and occlusive injury. The clinical changes observed following peripheral sympathectomy appear to be related to postsurgical correction of abnormal arteriovenous shunting and to improved nutritional blood flow to ischemic areas. This accounts for the resultant diminution of pain and healing of ulcers observed in these patients after surgery.

Adult↗

PubMed1994

Decreased microvascular perfusion in the rabbit ear after six hours of ischemia.

The cellular injury produced by reperfusion of ischemic tissue with oxygen-rich blood has been studied in numerous tissues but has not been investigated extensively in thermoregulatory tissue. This study was designed (a) to compare 4 and 6 hours of ischemia to document the evidence of impaired capillary perfusion after resumption of blood flow (reperfusion injury) in a thermoregulatory end organ (the rabbit ear), and (b) to examine, with use of vital capillaroscopy (VC) and laser Doppler flowmetry (LDF), the altered microvascular blood flow in the rabbit ear after ischemia and reperfusion. One ear from each of five rabbits underwent warm ischemia for 4 hours. VC showed no deficits of capillary perfusion in these ears after reperfusion; LDF measurements in both ears also demonstrated no significant difference between control and reperfusion blood flow. One ear from each of eight additional rabbits underwent 6 hours of warm ischemia. LDF values were significantly reduced in the ischemic ear after reperfusion as compared with baseline measurements for that ear and as compared with the control ear. VC showed arrested perfusion and static plasma gaps within three to five capillaries per high-power field (an area of 300 x 500 microns) in the ischemic ear and good perfusion of all vessels in the contralateral control ear. This evidence of reperfusion injury in a thermoregulatory end organ may help to explain the poor functional result that often occurs after replantation of an amputated digit.

Animals↗

PubMed1994

Microvascular response in the rabbit ear to total body cooling: a model for study of human digits.

Conditions such as Raynaud's disease, cold intolerance following digit replantation, and reflex sympathetic dystrophy are all exacerbated by diminished blood flow in the digits. The rabbit ear, being similar to the human digit, is an excellent model for studying microvascular responses during thermoregulation and was used in this study of microcirculatory changes during total-body cold stress. In eight rabbits a window was placed in one ear each, and the underlying vascular beds were photographed with the unanesthetized animal at room temperature (23 degrees C) and in a cold room (6 degrees C). Luminal arterial diameters constricted more than venular diameters during cold stress (39.6% vs. 16.5%, respectively, of the control diameters; P = 0.014). All responses were linear; the slopes of the regression lines were significantly different between arterioles and venules (P < 0.0001). This study suggests that decreased circulation in response to cold is due to decreases in the diameter and number of vessels available for perfusion, as predicted by the Poiseuille equation.

Animals↗

PubMed1993

Patterns of microvascular response associated with reflex sympathetic dystrophy of the hand and wrist.

The diagnosis of reflex sympathetic dystrophy is based on clinical presentation and often the presence of a positive three-phase technetium bone scan result. This study compared vasomotor control patterns between reflex sympathetic dystrophy patients with positive bone scan results and those with negative results. Both groups showed similar vasomotor responses to isolated cold stress testing--warm, cold, and transitional patterns of response were identified in both groups. Thus, this study demonstrates that a positive technetium bone scan result does not correlate with vasomotor disturbances in patients with reflex sympathetic dystrophy of the hand.

Adult↗

PubMed1993

Measurement of hand microvascular blood flow with isolated cold stress testing and laser Doppler fluxmetry.

Isolated cold stress testing applies cold thermal stress to an extremity for noninvasive study of skin surface temperature as an index of digital microcirculation. In this study, laser Doppler fluxmetry was combined with isolated cold stress testing to examine the relationship between digital thermoregulation (measured by isolated cold stress testing) and digital microcirculatory blood flow (measured by laser Doppler fluxmetry) in 50 healthy men and women. After a 5-minute baseline period, both hands were subjected to cold stress (average, 8 degrees C) for 20 minutes and then returned to room temperature for 20 minutes. Digital temperatures and laser Doppler measurements were graphed to document individual responses. The 25 women had lower digital temperatures, lower laser Doppler fluxmetry values, and less average rewarming than the 25 men. Statistical cluster analysis revealed a cold pattern, found predominantly in women, and a warm pattern, found predominantly in men. These patterns of response may help to elucidate the pathogenesis of the vascular occlusive syndromes occurring predominantly in women.

Adolescent↗

PubMed1993

Reflex sympathetic dystrophy in an adolescent.

The clinical course of an adolescent with reflex sympathetic dystrophy of the foot is presented. The potential problems of establishing objective diagnostic criteria for reflex sympathetic dystrophy are related to the dynamic nature of the disorder. Serial radiographic studies, radionuclide scans, and quantitative densitometric measurements may be useful in combination; isolated cold stress testing and laser Doppler fluxmetry are useful in assessing thermoregulation and vasomotor instability. A regimen of amitriptyline and phenytoin plus physical therapy with stress loading was useful in this patient, but in many patients the course is progressive, leading to chronic pain and debilitation.

Blood Flow Velocity↗

PubMed1992

Response of rabbit ear microvasculature to total body cooling as observed through a new implantable window.

A new implantable window was developed in order to study the native microcirculation of the rabbit ear. The responses of the ear microvasculature to total body cooling were studied before and after implantation of the window. No differences were found between arteriolar and venular vasoconstriction with cooling before and after implantation of the window. Arteriolar constriction was significantly greater than the venular response both before and after placement of the window (P = 0.014). Surface skin temperature of the instrumented and control ears was similar at room temperature (35.2 +/- 2.6 versus 36.1 +/- 1.0 degrees, respectively; P = 0.280); however, the instrumented ear was slightly warmer during cooling (17.9 +/- 1.9 versus 15.2 +/- 3.1 degrees; P = 0.024), suggesting increased blood flow in the instrumented ear. Details of construction and implantation of the window are described.

Animals↗

PubMed1990

Use of isolated cold stress testing in determining normal lower extremity thermoregulation.

Isolated cold stress testing was performed on 72 healthy subjects in order to evaluate the normal thermoregulatory potential of vessel beds in the acral areas of the lower extremity. Two patterns of response were demonstrated: a cool response in approximately 80% of subjects, and a warm pattern in approximately 20%. In the former, the responses to cold stress were more active and the temperatures lower; in the latter, there was little change in temperature in response to the cold stress. Both patterns correlated strongly with initial temperature, and neither pattern correlated with age, sex, or smoking habits. No subjects reported pain, numbness, or discomfort during the test. This study demonstrated that wide variations in thermoregulatory flow were possible without clinical symptoms, and suggested that nutritional blood flow was adequate to meet metabolic demands despite thermoregulatory modulation.

Adolescent↗

PubMed1990

Idiopathic scoliosis: correction of lateral and rotational deformities using the Cotrel-Dubousset spinal instrumentation system.

The Cotrel-Dubousset instrumentation (CDI) system developed between 1982 and 1984 is now being used extensively for the posterior correction of idiopathic scoliosis. In this study we compared the lateral and rotational correction obtained with CDI to that obtained with Harrington rod instrumentation and Drummond wiring. We matched 14 patients who had had CDI by age and sex with 14 patients who had had either Harrington rod instrumentation (n = 5) or Drummond wiring (n = 9). Average lateral curve correction was significantly better with CDI than with the combination of the other systems (71.9% and 56.4%, respectively; P less than .01). Average rotational correction was studied using the methods of Mehta, and Nash and Moe; all patients having CDI showed a median rotational improvement of 30 degrees; 57% of the comparison group had minimal improvement (P less than .01). These results suggest that CDI may offer a significant alternative to the Harrington and Drummond spinal instrumentation systems in the surgical management of adolescent idiopathic scoliosis.

Adolescent↗

PubMed1989

Thermoregulatory abnormalities of the foot.

Thermoregulatory abnormalities are well known but poorly understood phenomena. Pathologic alterations of microvascular blood flow occur in a variety of diseases of the foot, and often cause severe functional impairment. The structure, function, and methods for testing thermoregulatory abnormalities are reviewed. Pathologic manifestations of abnormal thermoregulation are also discussed.

Body Temperature Regulation↗

PubMed1988

Reflex sympathetic dystrophy of the knee after sensory nerve injury.

Reflex sympathetic dystrophy (RSD) of the knee is an extremely difficult problem to treat. This study examined the possible relationship between isolated injury to the infrapatellar branch of the saphenous nerve (IPBSN) and the etiology and natural course of RSD. Thirty-five patients with clinically significant sympathetic dystrophy of the knee were examined retrospectively. All patients (100%) had clinical evidence of insult to the IPBSN. Thirty-three patients (94%) were found to have vasomotor instability as measured by isolated cold stress testing (ICST). All patients in this population of 33 were treated with vasoactive therapies. Subjective improvement was noted in 20 patients (p = NS). Initial ICSTs of improved and unimproved patients were compared. Baseline temperatures were significantly warmer in patients who improved with therapy (p less than 0.05), and a warmer trend was evident throughout all phases of the test in those who improved compared with those who did not. Eighty percent of patients treated within 1 year improved with one or more vasoactive therapies, whereas only 44 percent improved when treatment was started after 1 year, indicating a significant population difference (p less than 0.05).

Adult↗