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Biomedical subjects

T G Lynch

Publications and source records attributed to T G Lynch.

At least 55 records · Page 3Linked to original sources
PubMed1984

Interpretation of Doppler segmental pressures in peripheral vascular occlusive disease.

Measurement of Doppler segmental arterial pressures in the lower extremity using narrow pneumatic cuffs has become a standard noninvasive diagnostic technique. Correlation between arteriographic and noninvasive studies was available for 345 aortoiliac segments and 326 femoropopliteal segments. If stenoses of 50% or greater and occlusions were considered hemodynamically significant, the sensitivity to aortoiliac disease was 97%, but only 67% to femoropopliteal disease. The specificity for hemodynamically insignificant disease was 50% and 68%, respectively. Accuracy was influenced by the presence of associated aortoiliac or femoropopliteal disease. The sensitivity to hemodynamically significant femoropopliteal disease was 55% if there was associated aortoiliac disease, and 89% in its absence. In the presence of significant femoropopliteal disease, specificity for the absence of aortoiliac disease decreased from 70% to 41%.

Angiography↗
PubMed1984

Influence of prostacyclin on distribution of canine femoral blood flow.

Prostacyclin (PGI2) has been used clinically in the treatment of ischemic peripheral vascular disease. While intravenous infusions have been reported to be beneficial, the preferred route of administration (intravenous or intraarterial) and the influence of PGI2 on distribution of femoral blood flow have yet to be established. Bilateral femoral arterial blood flow was measured electromagnetically in 10 anesthetized adult mongrel dogs. The distribution of femoral arterial blood flow (FAQ) to skin, muscle, bone, and arteriovenous anastomoses (AVA) was determined by using femoral intraarterial injections of radioactively labeled microspheres before, during, and 30 min after 20-min intravenous (n = 5) and intraarterial (n = 5) infusions of PGI2 at 0.1 microgram kg-1 min-1. Control FAQ was 76 +/- 15 (mean +/- SEM) ml/min and its distribution to skin, muscle, bone, and AVA was 13 +/- 3%, 43 +/- 8%, 17 +/- 4%, and 26 +/- 7%, respectively. Arterial pressure was 127 +/- 7 mm Hg. Intraarterial infusions of PGI2 significantly (P less than 0.05) increased FAQ to 240 +/- 43 ml/min which was sustained throughout the infusion. Distribution of FAQ to skin increased significantly (P less than 0.05) to 47 +/- 8%, while that to the muscle of the thigh decreased to 17 +/- 4% (P less than 0.05). During intravenous infusion of PGI2 at the same concentration, FAQ did not change significantly and its distribution remained unchanged; however, there was a significant (P less than 0.05) reduction in arterial pressure to 78 +/- 6 mm Hg. No significant changes occurred in cardiac output, pulmonary arterial pressure, arterial blood gases, paw or core body temperatures.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

The assessment of skin blood flow in peripheral vascular disease by laser Doppler velocimetry.

The helium-neon laser Doppler (LD) is designed to measure skin blood flow velocity (SBFV). Flow velocity and pulse wave amplitude are expressed in millivolts (mv) relative to a zero-flow reference. The authors have reviewed their initial experience in ten persons (20 limbs) without peripheral vascular disease (PVD, group I) and nine patients (12 limbs) with severe PVD (group II). The finger, palm, great toe, and forehead had a significantly (P less than 0.05) greater flow velocity than the plantar and dorsal foot, distal and proximal leg, thigh, chest, arm, and forearm. Baseline and hyperemic SBFV, measured at the great toe, were compared in groups I and II. In group I, the baseline SBFV (mv, mean +/- standard error of the mean (SEM] in the great toe was 197 +/- 38 compared with 67 +/- 12 in group-II patients (P less than 0.05). The pulse wave amplitude (mv, mean +/- SEM) was 77 +/- 14 in group I and 5.4 +/- 1.1 in group II (P less than 0.05). The time to maximal hyperemic response (seconds, mean +/- SEM) in group I was 18 +/- 1.5 compared with 150 +/- 14 in group II (P less than 0.05). LD is a sensitive indicator of changes in SBFV, allowing differentiation between normal persons and patients with PVD. The LD tracing in patients with PVD is characterized by a baseline SBFV that is significantly less than normal and also by the attenuation or absence of pulse waves. The diagnostic accuracy is enhanced by the use of reactive hyperemia.

Adult↗
PubMed1984

Effects of intravenous and intra-arterial infusions of prostaglandin E1 on canine hindlimb blood flow distribution.

Prostaglandin E1 (PGE1) has been used clinically in the treatment of ischemic peripheral vascular disease. However, the preferred route of administration and its influence on the distribution of blood flow to the skin, muscle, bone, and arteriovenous anastomoses ( AVAs ) have yet to be established. Bilateral femoral arterial blood flow was measured electromagnetically in 10 anesthetized adult mongrel dogs (mean weight 16.5 kg). The distribution of femoral arterial flow to the skin, muscle, bone, and AVAs was determined with use of femoral intra-arterial injections of radioactively tagged microspheres (15 +/- 1 mu) before, during, and 1 hour after 20 minutes of intravenous and intra-arterial infusions of PGE1 at 0.1 microgram kg-1 min-1. Intra-arterial infusions caused a significant (P less than 0.003) increase in femoral arterial flow (462 +/- 58 ml X min-1), which was sustained throughout the infusion. The distribution of flow to the skin increased significantly (P less than 0.01) to 24.1 +/- 2.1%, whereas that through AVAs was significantly (P less than 0.05) decreased to 3.2 +/- 0.9%. Femoral arterial blood flow did not change during intravenous infusions; however, there was a significant (P less than 0.01) reduction in the distribution to muscle (41.1 +/- 10.5%) associated with a significant (P less than 0.02) increase in distribution through AVAs (30.8 +/- 11.5%). These data demonstrate the superiority of intra-arterial infusion over intravenous infusions of PGE1 in the canine hindlimb. There was a significant increase in femoral arterial blood flow with increased distribution to the skin and decreased shunting. Femoral arterial blood flow did not change during intravenous infusions; however, a reduction in the distribution of flow to the muscle was accompanied by an increase in shunting.

Alprostadil↗
PubMed1984

Revascularization of the profunda femoris artery for limb salvage.

The clinical outcome of 88 profundaplasties in 70 patients operated upon during the period 1978 to 1982 was related to indications for operation, status of arterial run-off, influence of a concomitant inflow procedure, and changes in Doppler ankle-brachial index (ABI). Operative procedures were performed for rest pain (49 limbs), ulceration (24 limbs), and gangrene (13 extremities). Primary profundaplasty (PP) was performed in 26 (29%) cases. Sixty-two procedures (71%) were inflow profundaplasties (IP) performed in conjunction with other proximal reconstructions. Overall clinical success was achieved in 67 extremities (76%). When the operation was performed for rest pain, and the arterial run-off was good, success rate was 78 per cent and 79 per cent, respectively, as compared to 51 per cent and 57 per cent for ulceration/gangrene and poor arterial run-off. For PP, satisfactory outcome was noted in 69 per cent as compared to 79 per cent in IP. In the clinically successful profundaplasties, mean preoperative ABI was 0.29 and increased significantly to 0.53 postoperatively (P = 0.04). In the clinical failures, mean preoperative ABI was 0.32, and postoperative ABI was 0.38, which was not statistically significant (P greater than 0.05). Profundaplasty is a reliable operation particularly when the indication is rest pain, and the arterial run-off is good. Poor results can be anticipated when the procedure is performed for tissue loss, or if the arterial run-off is poor. Clinical outcome for the PP and IP groups were comparable.

Aged↗
PubMed1984

Popliteal and infrapopliteal arterial injuries. Differential management and amputation rates.

A 3-year clinical experience is analyzed to define preferred surgical management and amputation rates for popliteal as well as infrapopliteal arterial injuries. Ten patients with popliteal arterial trauma were successfully managed without amputation, however, five of 11 (45%) patients with infrapopliteal arterial trauma required amputation. While essentially all popliteal arterial injuries mandate repair, recommendations for repair or ligation of isolated tibial arterial injuries are based on presence of distal ischemia, the patient's associated injuries, as well as estimated operating time for reconstruction. With injury to two or three infrapopliteal arteries, distal ischemia is usually present and arterial repair indicated, unless there has been severe crush injury, prolonged delay, or extended surgery would jeopardize the patient's life. A management protocol for patients with distal ischemia related to popliteal or infrapopliteal arterial trauma should include prompt surgical intervention, liberal use of fasciotomy, intraoperative arteriography, as well as the selective use of intraluminal shunts.

Adolescent↗
PubMed1984

Penetrating carotid arterial trauma.

Injury to the carotid arteries from penetrating occurred in 15 patients during a recent 4-year interval. Fourteen of the injuries involved the common and/or internal carotid arteries, while one isolated external carotid injury was also encountered. Gunshot wounds accounted for eight injuries (53%) and sharp-edged instruments for seven injuries (47%). Surgical management included six ligations and nine vascular repairs. Neurologic status was normal on admission in eight patients, all of whom did well. Seven patients had preoperative neurological deficits; all three mortalities occurred in these patients. Identification of a preoperative deficit is significant because it conferred a guarded prognosis. However, hypotension and even circulatory arrest did not preclude recovery.

Adolescent↗
PubMed1983

Ultrasonic imaging and oculoplethysmography in diagnosis of carotid occlusive disease.

Pulsed Doppler ultrasonic imaging (UI) of the cervical carotid artery provides flow-dependent anatomic detail of the carotid bifurcation, while oculoplethysmography (Kartchner) (OPG-K) and ocular pneumoplethysmography (Gee) (OPG-G) reflect changes in flow and pressure resulting from hemodynamically significant lesions. We examined 66 patients prospectively with UI, OPG-K, and OPG-G to compare the relative accuracy of these techniques with contrast arteriography. Both UI and OPG-G were significantly more accurate than OPG-K. While the accuracies of UI and OPG-G were not significantly different, their combined use resulted in a significant increase in sensitivity compared with that of Doppler imaging alone. In addition, UI correctly identified 22 (85%) of 26 occlusions of the internal carotid artery. The use of UI and OPG-G together provided accurate anatomic and hemodynamic information useful in the evaluation of carotid occlusive disease.

Arterial Occlusive Diseases↗
PubMed1983

Femoral venous trauma: techniques for surgical management and early results.

During a 4 year period (1979 through 1983), 181 major arterial (69 percent) and 81 venous (31 percent) injuries were treated surgically. Of the venous injuries, 24 (30 percent) involved the femoral veins (9 common femoral, 15 superficial femoral). Management of these femoral venous injuries included lateral venorrhaphy in 10 cases (42 percent), venous patch angioplasty in 5 cases (21 percent), end-to-end anastomosis in 4 cases (17 percent), interposition autogenous saphenous vein grafts in 3 patients (12 percent), and ligation in 2 cases (8 percent). One case that included common femoral venous ligation and one that included a failed interposition saphenous vein graft in the superficial femoral vein subsequently were managed with in situ saphenous vein bypass. For one interposition saphenous vein graft repair of the common femoral vein we utilized the spiral vein graft technique. Excluding one early death from associated injuries and one superficial femoral venous injury managed by ligation without postoperative complications, 17 of 23 (74 percent) femoral venous repairs were judged patent postoperatively (13 confirmed by venography and 4 by noninvasive testing). The adjuvant use of intermittent pneumatic calf compression and low molecular weight dextran appears to have been beneficial in maintaining patency of the femoral venous repairs. Early clinical follow-up demonstrated the presence of edema in 6 of 8 cases (75 percent) initially treated by ligation or complicated by postoperative occlusion. Early postoperative edema, present in 4 of 17 (24 percent) patients with patent venous repairs, had resolved by the time of discharge. We recommend routine repair of femoral venous injuries. When significant edema or ischemia develop following obligatory venous ligation or postoperative occlusion of a venous repair, revision or venous bypass should be considered.

Adolescent↗
PubMed1983

Treatment of frostbite with intra-arterial prostaglandin E1.

Prostaglandin E1 (PGE1) is a vasodilator that inhibits platelet aggregation. Its use has been effective intra-arterially in treating ischemic peripheral vascular disease. Its potentially beneficial effect in treating frostbite injuries has not been studied and prompted this investigation. A standard frostbite injury was induced by immersing the hindlimbs of New Zealand white rabbits in an ethylene glycol bath maintained at -15 C. Forty animals were separated into eight equal groups (N = 5). Groups I through V were allowed to slowly rewarm at room temperature (21-22 C), while Groups VI through VIII underwent rapid rewarming in a water bath at 42 +/- 1 C. Groups I and VI received no further treatment. Groups II and VII received intra-arterial bolus injections of saline. Group III received intra-arterial bolus injections of reserpine (2.5 X 10(-3) mg/kg-1). Group IV received intra-arterial bolus injections of PGE1 (10(-1) micrograms/kg-1). Groups V and VIII received 3-hour intra-arterial infusions of PGE1 (10(-1) micrograms/kg-1 min-1). Tissue loss was graded numerically after 30 days. Group V (slow rewarming plus 3-hour PGE1 infusion) had significantly (P less than 0.5) less tissue loss than Group I (slow rewarming alone) and Group II (slow rewarming plus saline). Group V was not significantly different from Groups VI through VIII (rapid rewarming). Group III (slow rewarming plus bolus reserpine) and Group IV (slow rewarming plus bolus PGE1) were not significantly different from Group I (slow rewarming alone). The data suggest a clinical application for the use of PGE1 in frostbite patients who have not undergone rapid rewarming.

Animals↗
PubMed1983

Impedance plethysmography. Noninvasive diagnosis of deep venous thrombosis and arterial insufficiency.

The versatility of impedance plethysmography (IPG) in the diagnosis of arterial and venous disease was evaluated in the clinical setting. Eighty-eight consecutive patients suspected of acute or chronic deep venous thrombosis (DVT) and undergoing ascending venography were evaluated using IPG. Venous capacitance (VC) and venous outflow (VO) were expressed as a per cent impedance change (% delta I). The evaluation was considered as abnormal if the VC was less than 1.85% delta I and the VO less than 0.95% delta I. The overall accuracy was 90 per cent with a sensitivity of 92 per cent and specifity of 93 per cent. Arterial blood flow (ABF) was measured in normal volunteers (20 limbs) and patients with intermittent claudication (20 limbs) and rest pain (16 limbs). Resting ABF (cc/100 ml/min) did not differ (P greater than 0.05) in the normal volunteer (4.3 +/- 0.4) and patients with intermittent claudication (4.6 +/- 0.5), but both were significantly greater (P less than 0.05) than ABF in patients with rest pain (3.2 +/- 0.2). Peak ABF during reactive hyperemia (RH) was significantly greater (P less than 0.001) in normal volunteers (24.8 +/- 1.6) than in claudicators (10.5 +/- 1.3), and both flows were significantly greater (P less than 0.0001) than the peak ABF in patients with rest pain (5.3 +/- 0.5). IPG may be used in the assessment of arterial and venous disease. It provides a sensitive test with which to screen patients with suspected DVT. In addition, it is a valuable adjunct in differentiating normal limbs from those with intermittent claudication and/or rest pain.

Arterial Occlusive Diseases↗
PubMed1983

The role of real-time B-mode ultrasonography and ocular pneumoplethysmography following carotid endarterectomy.

Real-time B-mode ultrasonography and ocular pneumoplethysmography (OPG-G) were used to evaluate 41 patients (54 arteries) following carotid endarterectomy. Thirteen patients had bilateral procedures. Recurrent stenosis was observed in three (6%), and postoperative occlusion in three (6%). In one symptomatic patient, the origin of an occluded external carotid artery was the source of atheroemboli. Only two of the seven patients were symptomatic and three of the seven had hemodynamically insignificant stenoses. Of the three patients with recurrent stenosis, two had a normal OPG-G and demonstrated the value of combinate noninvasive evaluation. The noninvasive diagnosis in these two cases was based on B-mode ultrasonography. Of the three postoperative occlusions, one had a normal OPG-G. Since the OPG-G cannot distinguish stenosis from occlusion, B-mode ultrasonography was necessary to demonstrate the presence of an occluded internal carotid artery and the absence of internal carotid flow in each case. B-mode ultrasonography also permitted the identification of several characteristic postoperative findings. An intimal shelf was often observed, corresponding to the proximal limit of the endarterectomy. Seventy-four per cent demonstrated thickening of the arterial wall and 45 per cent were observed to have calcification in the area of the endarterectomy. The true incidence of recurrent disease following carotid endarterectomy is uncertain, but it probably exceeds those estimates based on symptomatic recurrence. Because of the incidence of asymptomatic and/or hemodynamically insignificant disease, we recommend the routine use of noninvasive studies following carotid endarterectomy.

Arterial Occlusive Diseases↗
PubMed1982

Differential patency and limb salvage for polytetrafluoroethylene and autogenous saphenous vein in severe lower extremity ischemia.

Polytetrafluoroethylene (PTFE) was compared to autogenous saphenous vein (ASV) in 133 femoropopliteal and femorotibial or peroneal bypass procedures performed in limb salvage during a 4-year period. PTFE was used as an alternative prosthesis in the absence of a suitable ASV. Sixty-nine femoropopliteal bypasses (FPBPs) were studied--36 with ASV and 33 with PTFE. Sixty-four femorotibial or peroneal bypasses were categorized as femoral distal bypasses (FDBPs)--34 with ASV and 30 with PTFE. With a 3-year clinical follow-up, cumulative function rate (CFR)--patency including thrombectomy--for FPBP with ASV was 65% as compared to 53% for PTFE (P greater than 0.05), whereas the limb salvage rate (LSR) was 75% with ASV and 56% for PTFE (P greater than 0.05). However for FDBP, the GFR was 55% for ASV and 7% for PTFE, whereas the LSR was 55% with ASV and 26% for PTFE. The cumulative patency rate (CPR)--initial thrombosis of a prosthesis as an endpoint--was not significantly (P greater than 0.05) different from CFR, suggesting that thrombectomy with or without distal anastamotic revision does not contribute to patency of the PTFE prosthesis in these limb salvage cases. PTFE was a suitable alternative to ASV for FPBP; however, PTFE is recommended for FDBP in selected cases only.

Blood Vessel Prosthesis↗
PubMed1982

Aortofemoral bypass grafting: Microvel.

One hundred seventy-five patients underwent elective aortofemoral bypass during the years from 1976 to 1979. One hundred eighteen of these patients received a knitted double velour prosthesis (Microvel) and the remainder received standard knitted Dacron. All patients had been followed for a minimum of 12 months. Early graft thrombosis occurred in three limbs, and these were restored by reoperation for 100 per cent patency at discharge from the hospital. The operative mortality was three patients (1.7%). Complications included myocardial infarction (three/one death), renal failure (one/one death), respiratory failure (one/one death), cerebrovascular accident (four), and superficial wound infection (five). Late complications were infrequent, but included seven graft limb occlusions in six patients (3.4%), and one graft infection, one ureteral obstruction, and one false aneurysm. Among the 256 symptomatic extremities, claudication was completely relieved in 199 (78%) and substantially improved in an additional 48 (18.5%). Hemodynamic assessment with arm/ankle or arm/high thigh indices improved in parallel with symptomatic relief. Thus, only nine (3.5%) symptomatic extremities failed to improve with the proximal reconstruction, requiring distal reconstruction or amputation. The authors remain advocates of aortofemoral grafting with end-to-end proximal anastomosis and hooding of the distal anastomosis over the profunda origin for most aortoiliac occlusive diseases. Our recent experience with double velour graft and this technique have been very satisfactory.

Adult↗
PubMed1982

Comparison of continuous-wave Doppler imaging, oculopneumoplethysmography, and the cerebrovascular Doppler examination.

Previous reports of continuous-wave Doppler imaging have combined that technique with periorbital Doppler studies. In the present report, 75 patients with findings suggestive of cerebrovascular insufficiency were evaluated using continuous-wave Doppler imaging, oculopneumoplethysmography (OPG-G) and the cerebrovascular Doppler examination (CDE). Each test was interpreted independently. Doppler imaging had an overall accuracy of 85%, with a 68% accuracy in identifying 50-70% stenoses and a 69% accuracy in identifying high-grade stenoses (greater than 70%) and occlusion. OPG-G had an overall accuracy of 85%, with a 55% sensitivity for 50-70% stenoses and an 89% sensitivity for high-grade stenoses and occlusion. The CDE had an overall accuracy of 84% and a 50% sensitivity for stenoses of 50-70% and an 88% sensitivity for high-grade stenoses and occlusion. As an independent technique, continuous-wave Doppler imaging achieves an overall accuracy comparable to that of OPG-G or the CDE. Its sensitivity to high-grade stenosis and occlusion, however, is less than that of the other techniques. Since CDE and OPG-G had a 94% sensitivity to carotid occlusion and a combined sensitivity to high-grade stenoses and occlusion of 88% and 89%, respectively, their combined use with Doppler imaging offers sensitivity to and differentiation of stenoses from occlusion.

Carotid Artery Diseases↗
PubMed1982

Differential hyperemic responses following femoral arterial and thigh cuff occlusion in the canine hindlimb.

The hyperemic response following arterial reconstruction is variable. To further evaluate this response, arterial blood flows in the canine hindlimb were compared following isolated femoral arterial occlusion and after thigh cuff tourniquet occlusion, which also obstructs collateral circulation. Arterial occlusion and tourniquet occlusion produced significant (P less than 0.05) increases in femoral arterial flow after all intervals of occlusion, except following 30 minutes of isolated arterial occlusion. Isolated arterial occlusion and tourniquet occlusion produced comparable hyperemic responses through five minutes of occlusion. However, tourniquet occlusion produced a significantly greater increase (P less than 0.05) in femoral flow when occlusions exceeded five minutes. These data suggest that the extent of collateralization may moderate the postobstructive hyperemic response following aortic and femoropopliteal reconstruction. The collateral recruitment during isolated arterial occlusion may be responsible for a diminished hyperemic response with time, while obstruction of the collateral circulation during tourniquet occlusion may result in a greater hyperemic response.

Animals↗