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Biomedical subjects

D T Ubbink

Publications and source records attributed to D T Ubbink.

51 records · Page 3Linked to original sources
PubMed1995

Survival of arteriovenous fistulas and shunts for haemodialysis.

OBJECTIVE: To formulate a standard for assessing functional patency of vascular access and to present long-term results of vascular access in a group undergoing dialysis, in particular the effects of percutaneous transluminal angioplasty (PTA). DESIGN: Retrospective study 1971-1980, prospective study 1980-1991. SETTING: A unit for haemodialysis in a regional hospital, The Netherlands. SUBJECTS: All 259 patients treated from 1971 to 1991 in a programme for chronic haemodialysis. INTERVENTIONS: All interventions, surgical and radiological, needed to maintain vascular access. MAIN OUTCOME MEASURES: Intervention free periods, patency of access, life expectancy of access, and early failure rate (within 4 days). Patency of access before and after PTA. RESULTS: A total of 1179 interventions were made. 407 Arteriovenous (A-V) fistulas and shunts were constructed, and there were 519 surgical reoperations and 253 PTAs. The secondary cumulative patency rate for the autogenous distal A-V fistulas (Cimino) was 79% at one year, 68% at two years, and 59% at three years. Routine use of PTA from 1986 onwards resulted in a rise in secondary cumulative patency for Cimino A-V fistulas after two years from 65% to 80% (p > 0.05). CONCLUSIONS: To describe and assess vascular access the patency rate alone is not sufficient; intervention free periods and life expectancy must also be given. Routine use of PTA with the Cimino A-V fistula resulted in an appreciable but not significant increase patency at two years.

Adolescent↗
PubMed1993

Skin microcirculation in diabetic and non-diabetic patients at different stages of lower limb ischaemia.

One hundred and one non-diabetic and 54 diabetic patients suffering from lower limb ischaemia were divided into (i) asymptomatic subjects, (ii) claudicants, (iii) critically ischaemic patients, i.e. Fontaine III or IV patients with either an ankle pressure < 51 mmHg or a toe pressure < 31 mmHg, and (iv) Fontaine III or IV patients in whom ankle and toe pressures could not be assessed due to vessel wall sclerosis or skin ulceration. Skin microcirculation was investigated to assess (a) the compounding effect of diabetes in leg ischaemia and (b) the additive value of microcirculatory investigation in the appreciation of the severity of the ischaemic disease. The techniques used included capillary microscopy, transcutaneous oximetry and laser Doppler fluxmetry. The severity of ischaemia was readily discernable using microcirculatory techniques. The presence of diabetes appeared to change skin microcirculatory perfusion, but especially in critically ischaemic patients, the microcirculation was no more compromised than non-diabetics. Using skin oxygen tension measurements, a positive predictive value of 77% was obtained in the detection of critical ischaemia, when a cut-off value of 30 mmHg was applied. Seventy per cent of patients, in whom the severity of ischaemia could not be classified using blood pressure measurements, could be classified as critically ischaemic on the basis of microcirculatory investigation. In conclusion, the influence of diabetes on the microcirculation is outweighed by the effects of atherosclerosis when vascular disease becomes severe. Techniques to investigate skin microcirculation are a useful way of assessing the severity of lower limb ischaemia in the presence of diabetes mellitus or if peripheral blood pressures cannot be obtained.

Aged↗
PubMed1993

Creation of a distal arteriovenous fistula improves microcirculatory hemodynamics of prosthetic graft bypass in secondary limb salvage procedures.

PURPOSE: In patients with critical limb ischemia, poor distal arterial runoff, and absence of autogenous veins, the use of an artificial graft and an arteriovenous fistula might be a valuable option. However, in these patients little information is available regarding preoperative and postoperative microcirculatory hemodynamics after this type of intervention. METHODS: With the use of intravital capillary microscopy, we studied the effect of distal revascularization on the microcirculation in 26 patients with critical limb ischemia. All patients had had failed vascular reconstructive operations, and artificial grafts were required because of the absence of autogenous veins. Patients were prospectively investigated and divided into two groups: 12 patients received a femorocrural bypass with polytetrafluoroethylene grafts, and 14 patients underwent the same procedure with the creation of an arteriovenous fistula at the site of the distal anastomosis and ligation of the proximal vein. Red blood cell velocity was measured before and after arterial occlusion to determine microcirculatory hemodynamic alterations. RESULTS: Immediate postoperative graft patency was achieved in all 26 patients. The 1-year cumulative graft patency rate was 64% in the group that had creation of an arteriovenous fistula, which was significantly higher (p < 0.01) compared with that in the group in which a fistula was not created (21%). The 1-year cumulative foot salvage rate was 72% in the patients with an arteriovenous fistula and 43% in the patients without a fistula (p < 0.05). Red blood cell velocity increased similarly in both groups after the bypass procedure. Peak and time to peak red blood cell velocity also improved significantly in both groups; however, comparing both groups, peak and time to peak red blood cell velocity were significantly better (p < 0.05) in the patients with an arteriovenous fistula and remained significantly higher during the follow-up period. CONCLUSIONS: In conclusion, creation of an adjunctive arteriovenous fistula at the distal anastomosis of a prosthetic graft appears to improve microcirculatory hemodynamics in the nutritional capillary vascular bed. Improved graft patency and foot salvage rates suggest that this procedure benefits patients with critical limb ischemia who have no usable veins.

Adult↗
PubMed1992

Assessment of the microcirculation provides additional information in critical limb ischaemia.

Systolic ankle and toe pressure measurements are considered to be the best way of documenting arterial occlusive disease. In the European consensus, chronic critical limb ischaemia is defined as persistent pain with an ankle pressure lower than 50 mmHg. To investigate the possible adjunct value of microcirculatory assessment, capillary microscopy and transcutaneous oximetry were performed in 21 asymptomatic persons (F1), 89 claudicants (F2) and 54 patients with critical limb ischaemia (F3/4). Capillary morphology (diameter, density) and dynamics [red blood cell velocity (RBCV), peak RBCV and time to peak RBCV], as well as transcutaneous oximetry parameters were determined for each Fontaine group and compared with ankle and toe pressure measurements. Despite considerable overlap, ankle and toe pressures were significantly (p less than 0.001) different between F1, F2 and F3/4 patients. Capillary density (p less than 0.05), diameter (p less than 0.05), peak RBCV (p less than 0.05) and time to peak RBCV (p less than 0.01), as well as transcutaneous oximetry parameters (p less than 0.001) were significantly different between all groups and impaired with progression of ischaemia. However, a similar overlap between all groups was observed, except the supine TcpO2 parameter which separated F3/4 patients completely from the other groups. In all patients with critical limb ischaemia, dynamic parameters, such as peak RBCV (p less than 0.01) and time to peak RBCV (p less than 0.001), were significantly lower as compared to non-critically ischaemic patients, irrespective of an ankle pressure below or above a value of 50 mmHg, illustrating the additional value of microcirculatory assessment in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Microvascular reactivity differences between the two legs of patients with unilateral lower limb ischaemia.

Posturally induced microvascular constriction in the skin of the leg is disturbed in severe ischaemia. It is unknown whether this disturbance is of local or central origin and whether the stage of ischaemia at which this disturbance occurs differs when the nutritive and thermoregulatory flow levels are compared. We investigated the effect of posture on the skin microcirculation in 21 patients with unilateral severe ischaemia. The results were compared with those from the contralateral, asymptomatic leg and with results from 11 age-matched controls. Patients were investigated in supine and sitting positions, using capillary microscopy to measure nutritive flow, and laser Doppler fluxmetry (LDF) to measure thermoregulatory flow, of the big toes. In the supine position, capillary flow and LDF were lower in the diseased than in the asymptomatic and control legs. After changing from the supine to the sitting position, capillary perfusion decreased in all three groups, but was most pronounced in the controls. Laser Doppler flux decreased in the controls, but increased in the diseased legs, suggesting disturbed vasoconstriction mechanisms in the deeper skin microvessels. These findings indicate that in severe limb ischaemia, posturally induced microvascular reactivity is sustained at the nutritive level but not at the thermoregulatory level. This disturbed reactivity is considered a local phenomenon, as it is not observed in the contralateral leg.

Adult↗
PubMed1992

The relevance of posturally induced microvascular constriction after revascularisation in patients with chronic leg ischaemia.

In patients with severe chronic lower limb ischaemia, postural vasoconstriction is disturbed, resulting in enhanced skin microcirculatory perfusion on leg dependency. After vascular reconstructive surgery, postoperative oedema formation is frequently seen. In 31 patients with leg ischaemia undergoing revascularisation we investigated whether and, if so, for how long after surgery postural vasoconstriction would take to recover, and whether disturbed vasoconstriction correlates with the occurrence of postoperative oedema. Capillary microscopy and laser Doppler fluxmetry were used to assess nutritional and total skin perfusion, respectively. The measurements were performed before and up to 37 days after surgery. After revascularisation, the mean ankle blood pressure index rose from 40 to 82%. All patients, except those with persistently disturbed vasoconstriction showed improved microcirculatory parameters. Postural vasoconstriction was restored in 24 patients, occurring approximately on the eighth postoperative day. All patients who failed to recover vasoconstriction developed postoperative oedema. This study shows that the disturbance in postural vasoconstriction can be reversible, probably due to recovery of arteriolar smooth muscle tone, and that patients with persistently disturbed postural vasoconstriction, are prone to develop postoperative oedema.

Adult↗
PubMed1992

Capillary recruitment and pain relief on leg dependency in patients with severe lower limb ischemia.

BACKGROUND: Patients suffering from severe lower limb ischemia may experience pain relief on leg dependency despite the fact that dependency normally results in arteriolar vasoconstriction. To clarify this possible paradox, skin microcirculation of the limb was investigated in 75 patients with different stages of lower limb ischemia and in 12 asymptomatic subjects. METHODS AND RESULTS: Using nailfold capillary video microscopy, red blood cell-perfused capillary density and diameter and red blood cell velocity were assessed in supine and sitting positions. Capillary density increased by changing from the supine to the sitting position, especially in patients with limb-threatening ischemia (showing a 4.5-fold increase versus a 1.5-fold increase in asymptomatic subjects). In subjects without or with mild ischemia, capillary perfusion was two to four times lower in the sitting than in the supine position. In patients with limb-threatening ischemia, perfusion was strongly reduced, being slightly higher in the sitting position. Patients with relief of pain while sitting did not always have a higher capillary perfusion but did have a higher capillary density in the sitting position. CONCLUSIONS: The arteriolar postural vasoconstrictive mechanism at the nutritive level is still intact in subjects without or with mild ischemia but not in patients with severe ischemia. Capillary recruitment rather than disturbed arteriolar vasoconstriction could explain why patients with severe leg ischemia prefer leg dependency.

Adult↗
PubMed1991

Posturally induced microvascular constriction in patients with different stages of leg ischaemia: effect of local skin heating.

1. Skin microcirculation was investigated in 12 asymptomatic subjects and 76 patients, grouped according to their ankle-to-brachial systolic blood pressure index, in order to evaluate to what extent posturally induced microvascular constriction is dependent on the stage of leg ischaemia at different local skin temperatures. 2. Skin microcirculation was assessed in the supine and sitting position by using laser Doppler fluxmetry at unheated skin temperature and at 36 degrees C, and transcutaneous oximetry at 37 degrees C and 44 degrees C. 3. Skin perfusion and oxygenation diminished with decreasing ankle-to-brachial systolic blood pressure index. In healthy control subjects, perfusion and oxygenation were reduced when changing from the supine to the sitting position, but were enhanced in patients with severe leg ischaemia (ankle-to-brachial systolic blood pressure less than 30%), indicating disturbed posturally induced vasoconstriction. 4. Increasing the local skin temperature resulted in a higher perfusion and masked the posturally induced vasoconstriction in healthy subjects. In patients with severe leg ischaemia, however, perfusion was unaltered by the temperature increase, apparently because the microvessels were already maximally dilated. The induction of reactive hyperaemia produced no additional increase in perfusion or oxygenation. 5. It is concluded that posturally induced microvascular constriction in the skin is disturbed in patients with severe leg ischaemia (ankle-to-brachial systolic blood pressure index less than 30%). Disturbed microvascular constriction upon dependency was also seen in healthy subjects after local skin heating. This suggests that posturally induced vasoconstriction is mainly regulated by local mechanisms.

Adult↗
PubMed1990

Foot salvage and improvement of microvascular blood flow as a result of epidural spinal cord electrical stimulation.

Epidural spinal cord electrical stimulation has been suggested as an alternative treatment in patients with limb-threatening ischemia in whom vascular reconstructive surgery is not possible anymore. We studied the effects of epidural spinal cord electrical stimulation on microcirculatory blood flow in 20 patients with ischemic rest pain and ulcers. Angiography showed occluded crural arteries technically unsuitable for reconstructive surgery. Intravital capillary microscopy was used to assess capillary density and diameter and red blood cell velocity before and after a 1-minute period of arterial occlusion. After epidural spinal cord electrical stimulation 18 patients claimed immediate pain relief, which was confirmed by intravital capillary microscopy. Capillary density increased from 10 to 19/mm2 (p less than 0.001), red blood cell velocity increased from 0.088 to 0.496 mm/sec (p less than 0.001), and peak red blood cell velocity after arterial occlusion increased from 0.092 to 0.548 mm/sec (p less than 0.001). Two patients had no immediate pain relief; they did not show improvement of microcirculatory perfusion, and amputation was necessary. During the follow-up period (3 months to 3 years, mean 27 months), six other patients had recurrent ischemic pain, and amputation was necessary. In 12 patients pain relief continued, and ischemic ulcers healed; capillary microscopy confirmed improved microcirculatory blood flow. Microcirculatory parameters were significantly higher in respondents than in nonrespondents (p less than 0.001). Life-table analysis revealed a cumulative foot salvage of 80% and 56% after 1 and 2 years, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

'Idiopathic' second-trimester abortion--a reproductive failure.

The results of the investigation of all 238 immature deliveries (second-trimester abortions) that occurred in the period 1973 to 1985 in the Academic Hospital of the Vrije Universiteit in Amsterdam are presented. The incidence after 1979 was found to be increasing. Excluding all deliveries with a known cause, 126 'idiopathic' cases remained. In these, the obstetrical history of the women revealed a tendency to recurrent pregnancy wastage. The pregnancies frequently showed growth retardation of both fetus and placenta. Therefore, an extensive search for possible causes and an accurate evaluation of fetal development during a following pregnancy is advocated.

Abortion, Spontaneous↗
PubMedDate not supplied

Percutaneous transluminal angioplasty of peripheral bypass stenoses.

PURPOSE: To assess the success of percutaneous transluminal angioplasty (PTA) in treating peripheral bypass stenoses. METHODS: Patients who received a femoropopliteal or femorocrural bypass graft for limb ischemia were included in a duplex surveillance program. If duplex ultrasound revealed a short (<2 cm) severe (peak systolic velocity ratio >/= 4.5) stenosis, patients were scheduled for arteriography and PTA. Fifty-eight peripheral bypass stenoses in 39 grafts in 37 patients were treated with PTA. The cumulative primary patency of treated stenoses was calculated. RESULTS: During the first year after PTA 31 (53%) treated lesions remained patent, 15 (26%) lesions restenosed at a median interval of 5.0 (range 1-12) months and 4 (7%) bypasses occluded. The cumulative primary patency of 58 treated graft stenoses at 1 year was 60% [95% confidence interval (CI) 46%-74%] and 55% (95% CI 41%-70%) at 2 years. Graft body stenoses showed a better 2-year cumulative primary patency (86%; 95% CI 68%-100%) compared with juxta-anastomotic lesions (45%; 95% CI 29%-62%; p < 0.05). CONCLUSION: PTA is justifiable as the initial treatment of peripheral bypass stenoses. Nevertheless, the restenosis rate is rather high, especially in juxta-anastomotic lesions. Continuation of duplex surveillance after PTA and timely reintervention is recommended.

Aged↗
PubMedDate not supplied

Can the green laser doppler measure skin-nutritive perfusion in patients with peripheral vascular disease?

The recently developed green laser (GL; wavelength 543 nm) is thought to measure perfusion derived from a more superficial skin layer than does the standard near-infrared laser (RL; wavelength 780 nm). These lasers were used to investigate the disturbances in the different layers of skin perfusion in ischaemic legs before and after treatment and compared with capillary microscopy. Eighteen patients (20 legs) with different stages of leg ischaemia scheduled for a vascular intervention (11 males, 7 females; median age 73, range: 52-81 years; Fontaine stages II-IV) were investigated by means of capillary microscopy, visualising the nail fold capillary perfusion, and a laser Doppler, equipped with a special dual probe conducting both GL and RL. The probe was attached to the pulp and the dorsum of the big toe to assess skin perfusion at rest and during reactive hyperaemia, while sitting and while supine. Resting and hyperaemic perfusion using GL was low and significantly lower (p < 0.01) than with RL in both areas and positions. Laser Doppler perfusion was higher in the pulp than on the dorsum with both wavelengths (p < 0.05). The hyperaemia response was highest using GL and differed among the three techniques. Postural reduction of capillary and RL flow was reduced, but not with GL. After treatment, skin capillary perfusion improved more clearly than did the laser Doppler perfusion with either wavelength, while postural vasoconstriction improved only when measured with the capillary microscope. The differences found between RL and GL Doppler perfusion, but also between GL and capillary microscopy measurements suggest that the GL does measure the more superficial, but not exclusively the nutritive skin perfusion. Clinically, the use of the green laser in its present form in patients with leg ischaemia offers no advantage over the red laser.

Aged↗
PubMedDate not supplied

The usefulness of capillary microscopy, transcutaneous oximetry and laser Doppler fluxmetry in the assessment of the severity of lower limb ischaemia.

TMo date, capillary microscopy, transcutaneous oximetry (tcpO2) and laser Doppler fluxmetry are frequently used in the investigation of skin microcirculation in patients with lower limb ischaemia. The concomitant microcirculatory disturbances may be useful in addition to macrocirculatory parameters to discriminate the different degrees of ischaemic severity. The best ways of application of these methods and the choice of the best parameters to assess ischaemia have been insufficiently investigated. Therefore, skin microcirculation was investigated with the use of these techniques in 130 patients with different stages of lower limb ischaemia, divided according to their ankle-to-brachial pressure index (ABI). Patients were investigated in the sitting and the supine position. Measurements were performed at rest and during reactive hyperaemia following arterial occlusion, and before and after local skin heating. The reactive hyperaemic response using laser Doppler fluxmetry differed in every patient group investigated. Capillary red blood cell velocity was markedly impaired in critically ischaemic patients (ABI < 25%). Transcutaneous oxygen pressure measurements at rest rendered the highest positive predictive value (PV; 87%) to classify patients as having clinically severe ischaemia (Fontaine 3 or 4). Ankle and toe pressure measurements provided a PV value of 78%. Microcirculatory parameters and techniques appear to be useful as an addition to standard macrocirculatory techniques to assess the severity of lower limb ischaemia. This is particularly of importance in patients in whom macrocirculatory parameters are unattainable.

Adult↗
PubMedDate not supplied

Spinal cord stimulation in critical limb ischemia. A review.

This paper reviews the actual clinical experience and alleged working mechanisms of spinal cord stimulation (SCS) in the treatment of non-reconstructable critical leg ischaemia. SCS appears to be beneficial particularly for relief of pain and healing of ischaemic ulcers. The evidence available as to limb salvage is still dubious, because most of the studies performed so far are non-randomised, and different causes for peripheral ischaemia are studied simultaneously. Investigation of the local skin microcirculation, in particular by means of transcutaneous oxygen pressure measurements, appears important to select those patients that will benefit most of SCS treatment, to predict limb survival and to further elucidate the working mechanism of SCS.

Electric Stimulation Therapy↗