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Biomedical subjects

J H Eickhoff

Publications and source records attributed to J H Eickhoff.

At least 37 records · Page 2Linked to original sources
PubMed1985

The design of clinical graft studies.

This paper contains certain proposals for future graft studies. Graft failure should be defined as any occlusion of the graft. Time should be measured from the end of operation to the first occlusion of the graft. The results should be analysed by the Kaplan-Meier estimator, and patency rates should be compared by the log-rank test or Gehan's test. It is stressed that scientifically valid data can only be obtained in prospective, randomized trials.

Actuarial Analysis↗
PubMed1985

Normalization of local blood flow regulation in the ischemic forefoot after arterial reconstruction.

Two local blood flow regulating mechanisms were studied before and after arterial reconstruction in 30 limbs suffering from occlusive arterial disease. Changes in forefoot blood flow were measured from the washout of a subcutaneous 133xenon depot. Arterial and venous pressures were changed by passive lowering and elevation of the foot. In 14 limbs suffering from severe ischemia, the local vasoconstrictor response to increased venous pressure was abolished as blood flow increased 37% when the limbs were lowered 40 cm. Autoregulation of blood flow was abolished also as flow decreased 51% when the limbs were elevated 20 cm. The estimated vascular resistance was constant during lowering and elevation, indicating paralysis of the arterioles. The vasoconstrictor response had returned at the tenth postoperative day as blood flow decreased 32% during lowering. Autoregulation had also returned as blood flow remained almost constant during elevation to 40 cm. In 16 limbs with less severe ischemia, vasoconstrictor response as well as autoregulation was preserved before operation, and no disturbances occurred after operation. Despite the early normalization of local blood flow regulation, postoperative hyperemia developed in most limbs. Post-reconstruction edema developed after all but one of the 13 femorodistal bypass operations and after only one of the 17 aortoiliac reconstructions. This suggests that post-reconstruction hyperemia and post-reconstruction edema are not caused by arteriolar insufficiency.

Adult↗
PubMed1985

Orthostatic changes in first-toe blood pressure in normal subjects and in patients with occlusive arterial disease.

Orthostatic changes in first-toe systolic blood pressure, measured with cuff and strain-gauge technique, were compared with changes expected according to hydrostatic calculations. Twenty-five limbs with occlusive arterial disease were studied. When the first toe was lowered 40 cm below the heart, the toe blood pressure--corrected for changes in systemic blood pressure--rose on median 3.9 (-8.7 to 11.4) mmHg more than expected. The difference was statistically significant. Elevation of the first toe 40 cm above the heart did not lead to significant deviation from the expected blood pressure. Twelve normal limbs showed no significant deviations in blood pressure during the orthostatic changes. It is proposed that the additional increase in the indirectly measured systolic pressure also represents an additional increase in the mean arterial blood pressure. The mechanism of this additional increase seems to be reflex vasoconstriction in the distal tissues, reducing the pressure gradient across the proximal collateral vessels. The additional increment may contribute to the abnormalities of local blood flow regulation observed in ischaemic limbs.

Adult↗
PubMed1984

Forefoot capillary filtration rate measured during lowering in normal subjects and in patients with occlusive arterial disease before and after arterial reconstruction.

Capillary filtration rate (CFR) was measured by a mercury-in-silastic strain-gauge around the forefoot when the forefoot was lowered 40 cm below heart level. In seven normal limbs, CFR was 0.061 (0.049-0.086) ml (100 g min)-1 against 0.049 (0.016-0.071) ml (100 g min)-1 in 24 limbs with occlusive arterial disease (P = 0.01). About 8 days after arterial reconstruction CFR decreased to 0.039 (0.018-0.071) ml (100 g min)-1, but before 3 months after reconstruction CFR increased to normal values 0.061 (0.037-0.071) ml (100 g min)-1. The explanation offered for the reduced CFR before and immediately after arterial reconstruction is temporary thrombosis in the smallest distributing arteries and in the arterioles resulting in heterogeneous flow distribution and decreased fluid filtration in poorly perfused segments of the capillary bed. The results speak against increased capillary filtration as the aetiology of the post-reconstructive oedema.

Adult↗
PubMed1984

Direct determination of the tissue-to-blood partition coefficient for Xenon in human subcutaneous adipose tissue.

The tissue-to-blood partition coefficient for Xenon (lambda Xe) in the subcutaneous tissue in the forefoot was determined by physical and chemical analysis. The difference between patients with normal circulation (n = 10) and serve ischaemia (n = 13) was insignificant; pooled mean: 7.42 +/- 1.57 ml x g-1. The lambda Xe in the forefoot was significantly lower than lambda Xe of the abdominal wall (lambda Xe - abd: 8.67 +/- 1.27 ml x g-1; P = 0.03). The influence of oedema on the local blood flow [in ml x (100 g x min)-1] and on the post-reconstructive hyperaemia (in ml x min-1) is discussed. It is concluded that local blood flow determinations, based on 133Xenon wash-out rates, in individual cases, are not possible. In subcutaneous tissue with low lipid contents, the ratio between the post- and preoperative wash-out rates tend to underestimate the post reconstructive hyperaemia. This is due to the volume increase of the subcutaneous tissue being larger than the decrease of the tissue-to-blood partition coefficient due to the oedema.

Adipose Tissue↗
PubMed1983

A randomized clinical trial of PTFE versus human umbilical vein for femoropopliteal bypass surgery. Preliminary results.

PTFE (Goretex) and modified human umbilical vein (Biograft) vascular grafts were compared in femorodistal popliteal artery bypass surgery in a randomized clinical multicentre trial. During 18 months 104 patients (104 limbs) entered the trial. Twenty-five patients suffered from claudication, 54 suffered rest pain and 25 patients had ulceration or gangrene. The median preoperative ankle-arm blood pressure index was 0 . 34. Twenty-three limbs had 3 patent tibial arteries, 45 limbs had 2 tibial arteries, 31 limbs had 1 tibial artery while 5 limbs had an isolated popliteal segment. Thirty-six of the operations were redo-operations. Fifty-four patients were allocated to PTFE and 50 to umbilical vein. During follow-up (maximum 650 days) 24 PTFE grafts occluded against 12 umbilical veins. The 1-year patency rate was 40 per cent in the PTFE group against 75 per cent in the umbilical vein group (P = 0 . 014, Gehans test). During the first year the PTFE failure rate was on average 3 . 1 times higher than that of the umbilical vein.

Aged↗
PubMed1983

Effect of chronic sympathetic denervation upon the transcapillary filtration rate induced by venous stasis.

The effect of venous pressure elevation upon capillary filtration rate in the limb was studied in 6 chronically sympathectomized patients. Five healthy subjects served as controls. Volume changes of the forearm or calf were recorded by a strain-gauge plethysmograph. Relative blood flow in subcutaneous and muscle tissue during venous stasis was measured by the local 133Xe washout technique. In the denervated limbs there was a linear relationship between net capillary filtration rate and venous pressure elevation. In the controls a non-linear relationship was seen as venous pressure elevation of 40 mmHg only caused an increase in net filtration rate of about 66% of that expected from a linear relationship. In the denervated limbs of blood flow in muscle and subcutaneous tissue remained constant during venous pressure elevation of more than 30 mmHg whereas in the non-denervated limbs blood flow decreased by about 50% in both tissues. The results suggest that a local sympathetic veno-arteriolar (axon) reflex plays a dominant role for the reduced increase in net capillary filtration during large increases in venous pressure. The local axon reflex may therefore act as an edema protecting factor.

Adult↗
PubMed1983

Delayed distal blood pressure rise after partial arterial reconstruction for combined aorto-iliac and superficial femoral artery occlusive disease.

The blood pressure in the ankle and great toe was measured with cuff and strain-gauge technique in 39 patients after insertion of aorto-femoral bifurcation graft. In 40 limbs with patent superficial femoral artery (complete reconstruction) the distal blood pressure remained unchanged from the tenth postoperative day to follow-up after 12 to 26 months. In 30 limbs with occluded superficial femoral artery (partial reconstruction) the ankle/arm pressure index rose from 0.54 to 0.61 between the tenth day and late follow-up. The blood pressure in the great toe had increased by 8 mmHg on the tenth postoperative day and by additionally 17 mmHg during the next 12 to 26 months. The delayed pressure rise after partial arterial reconstruction presumably reflected development of collateral vessels from the deep femoral artery system. The clinical significance of the findings is discussed.

Adult↗
PubMed1982

Local regulation of blood flow and the occurrence of edema after arterial reconstruction of the lower limbs.

The relation between edema after arterial reconstruction of the lower limbs and various potential etiologic factors, including disturbances in local blood flow regulating mechanisms, was investigated in 22 patients with occlusive arterial disease. The occurrence of edema was unrelated to the severity of symptoms as well as to the perioperative changes in distal arterial blood pressure. Postreconstructive edema developed independently of postreconstructive hyperemia and of disturbances in the local vasoconstrictor response to increased venous pressure. The decisive factor for development of edema was the extensive dissection in the thigh and in the popliteal region required for femoropopliteal bypass surgery. Edema developed after nine of nine femoropopliteal bypass operations, and only after one of 12 reconstructions in the aorto-iliac or in the profound femoral segments (p = 0.001). It is concluded that the postreconstructive edema is a lymphedema due to surgical trauma, rather than the result of microvascular derangement.

Adult↗
PubMed1982

Changes after arterial reconstruction in the forefoot local vasoconstrictor response to increased venous transmural pressure.

Local blood flow regulation on the forefoot was studied by the 133Xe wash-out technique in twenty-seven patients before and after arterial reconstruction for occlusive arterial disease. In thirteen limbs with severe symptoms the local vasoconstrictor response to increased venous pressure was absent preoperatively, as blood flow in the foot increased in median by 47% when the foot was lowered 40 cm below the heart. Three months postoperatively the vasoconstrictor response had returned as blood flow decreased 28% during lowering. Fourteen limbs with milder symptoms had a vasoconstrictor response before operation. In nine limbs of this group treated with aortoiliac reconstruction the vasoconstrictor response was absent at the early postoperative examination, but the response returned till the late examination. It is concluded that the local vasoconstrictor response is normalized after arterial reconstruction. Disturbances may, however, occur in the postoperative period, possibly due to operative stress.

Adult↗
PubMed1982

Local regulation of subcutaneous blood flow in normal subjects and in migraine patients before and after single-dose ergotamine tartrate.

Local blood flow regulation of the foot was studied in 15 normal subjects and in nine migraine patients. Changes in arterial and venous pressures were induced by lowering and elevation of the limb. Changes in blood flow were estimated from the changes in the wash-out rate of a subcutaneous 133-Xenon depot. The local vasoconstrictor response to increased venous pressure elicited during lowering was identical in the normal subjects and in the migraine patients. During elevation, however, an abnormality in the autoregulation of blood flow could be demonstrated, as a decrease in blood flow during elevation to +40 cm was more pronounced in the patients than in the normal subjects (P = 0.04). About 3 h after 0.5 mg ergotamine tartrate/70 kg body weight i.v. the local regulation of blood flow had markedly changed in normal subjects as well as in migraine patients. During elevation to +20 and to +40 cm, blood flow increased significantly (P = 0.01 and P = 0.02). In two subjects the isotope depot was infiltrated with lidocaine and the ergotamine-induced increase in blood flow during elevation was blocked. The results may indicate that the veno-receptor of the veno-arteriolar reflex underlying the local vasoconstrictor response is a tension receptor, which due to the veno-constrictor effect of ergotamine is triggered even at heart level.

Adult↗
PubMed1982

Mechanism of ergotamine-induced decrease of peripheral systolic blood pressure in man.

We have previously reported a consistent decrease of peripheral-central systolic blood pressure (SBP) gradients after ergotamine. SBP was measured with cuffs and it is unknown whether measured values reflect changes of intra-arterial SBP or increase of vessel wall tone beneath the cuffs. We hence studied the effect of ergotamine tartrate 0.5 mg intravenously on finger-arm systolic gradients after the following procedures: Infiltration around finger arteries with papaverine (n = 2) and dihydralazine (n = 3), occlusion of blood supply to a finger by an inflated cuff before and 2 hours after ergotamine (n = 6). A normal reduction in finger-arm systolic gradients was seen. The ergotamine-induced decrease of peripheral SBP must therefore be due to a fall in peripheral intra-arterial SBP i.e. to contraction of arteries proximal to the digital arteries. Intra-arterial injection of 10 micrograms ergotamine tartrate caused similar decrease in finger-arm systolic gradients as intravenous administration of 0.5 mg (n = 1) indicating a peripheral site of action.

Adult↗
PubMed1982

The influence of changes in arterial blood pressure on transcutaneous oxygen tension (tcPO2) in the newborn.

The possible artefacts in transcutaneous oxygen tension (tcPO2) induced by fluctuations in arterial blood pressure were investigated in ten newborn babies. We mounted one tcPO2 electrode on the foot and another on the chest, and the local arterial blood pressure under the foot electrode was reduced 0.6-2.0 kPa (9-15 mmHg) by elevating the foot 11-19 cm above the heart level. In five mature newborns the tcPO2 of the foot decreased significantly (p = 0.015) during elevation by a mean valve of 0.029 kPa (0.22 mmHg) per mmHg decrease in mean arterial blood pressure. In five premature newborns the artefact was insignificant (p = 0.62). We conclude therefore that, in contrast to adults, the artefacts induced by minor fluctuations in arterial blood pressure in newborns are hardly of clinical importance.

Blood Pressure↗
PubMed1982

Is transcutaneous oxygen tension independent of variations in blood flow and in arterial blood pressure?

Whether transcutaneous oxygen tension (TcPO2) is independent of minor variations in perfusion under the TcPO2 electrode, as is claimed, was studied in 18 feet of 16 young healthy adults. The TcPO2 electrode was mounted on the dorsum of the foot and operated at 43 degrees C, while the blood pressure was changed by elevating and lowering the foot. During elevation the mean arterial blood pressure decreased corresponding to the hydrostatic pressure of the column of blood between the heart and the position of the foot. In every experiment TcPO2 decreased when the foot was elevated at an average rate of 1.2% per millimeter Hg change in mean arterial blood pressure. TcPO2 was negatively correlated to blood flow in normal unheated tissue, but significantly and positively correlated to blood flow in the heated, vasodilated tissue under the TcPO2 electrode. In the heated tissue normal blood flow regulation was abolished, and the perfusion under the electrode was mainly determined by the arterial blood pressure. It is concluded that TcPO2 in adults--and probably also in neonates--is affected by the minor or large variations in the perfusion under the electrode caused by fluctuations in arterial blood pressure.

Adult↗