Fluorescein angiography and distal arterial pressure in patients with arterial disease of the legs

Summary. Fluorescein angiography (FA) of the foot soles was performed in 119 patients with arterial disease of the legs. Fluorescein was injected rapidly intravenously and sequential photographs were taken of the foot soles. Densitometric measurements were performed on three areas of each foot image: the big toe, the foot pad (just proximal to the little toe) and the heel. The relationships between different FA measurements and systolic arterial pressure in the ankle or the big toe were analysed. The appearance times of fluorescence correlated inversely with ankle pressure (P<0·001). The initial slopes of the fluorescence–time curves at all three sites of measurement correlated with ankle pressure (P<0·001). The initial slopes of fluorescence–time curves of the big toe and the foot pad correlated with toe pressure (P<0·001). In 12 patients effective arterial pressure was lowered by elevation of the feet, and in eight patients external pressure was applied to the foot by enclosing it in a box. The changes in FA evoked by these manoeuvres further strengthened the relationship between arterial pressures and FA measurements. We conclude that FA is a good method for evaluating circulation in the foot when neither ankle nor toe pressure is obtainable. In addition, FA may be useful when vascular disease is suspected in the presence of normal pressures, because the fluorescence distribution pattern was clearly abnormal in 11 of 16 such feet.     

Comparison of two methods based on photoplethysmography for the diagnosis of peripheral arterial disease

Aim. To examine the interchangeability of two methods for distal pressure measurement based on photoplethysmography using a truncated or full display of the arterial inflow curve, respectively. Methods. Toe and ankle pressures were obtained from 69 patients suspected of peripheral arterial disease (PAD). Observer reproducibility of the curve readings was examined by blinded reassessment of the pressure curves in a randomly selected subgroup (60 limbs). Results. There were no significant differences in mean pressures between the two methods (p for all >?.455). The limits of agreement for the differences were ?15.0–15.4?mmHg for right toe pressures, ?16.3–16.2?mmHg for left toe pressures, ?14.2–15.7?mmHg for right ankle pressures, and ?18.3–17.7?mmHg for left ankle pressures. Correlation analysis revealed intraclass correlation coefficients ≥0.960 for all measuring sites. Cohen’s Kappa showed excellent agreement in diagnostic classification, with κ?=?0.930 for the diagnosis of PAD and perfect agreement in the diagnosis of critical limb ischemia (κ?=?1.000). The analysis of intra-observer variation for curve reading showed limits of agreement of ?3.9–4.0 for toe pressures and ?7.6–7.7 for ankle pressures for the method involving truncated display and ?3.1–3.2 for toe pressures and ?6.3–8.6 for ankle pressures for the method involving full display of the signal. Conclusion. The present study shows minimal differences in diagnostic classification, as well as in ankle and toe pressures, between the full display and the truncated display of the photoplethysmographic pulse signal. Furthermore, the inter-observer variation was low for both of the photoplethysmographic methods investigated.     

Is oscillometric ankle pressure reliable in leg vascular disease?

The objective of the study was to evaluate the validity of oscillometric systolic ankle pressure in symptomatic leg arterial occlusive disease. Ankle pressure measurements using oscillometric curves obtained using a standard 12‐cm cuff with a specially designed device for signal processing were validated against the continuous wave (CW) Doppler technique. Thirty‐four subjects without signs or symptoms of peripheral vascular disease (68 legs) and 47 patients with leg ischaemia (85 legs) varying from moderate claudication to critical ischaemia were examined. The oscillometric curves were analysed using several algorithms reported in the literature, based on the assumption that maximum oscillations are recorded near mean arterial pressure. In normals, reasonable agreement between CW Doppler and oscillometric methods was seen. When an algorithm that determined the lowest cuff pressure at which maximum oscillations occurred, and a characteristic ratio for systolic pressure of 0·52 was used, the mean difference between CW Doppler and oscillometry was 1·7 mmHg [range ?19 to +27, limits of agreement (2 SD) 21·1 mmHg]. In ischaemic legs, oscillometry overestimated systolic ankle pressure by a mean of 28·8 mmHg [range –126 to +65, limits of agreement 82·8 mmHg]. The difference was more pronounced among patients with critical ischaemia compared with claudicants, and also more evident among diabetics. The error of oscillometric pressure determination in subjects with leg arterial disease inversely increased with CW Doppler ankle pressure. In 39% of the recordings in legs with a CW Doppler systolic pressure below 100 mmHg, the oscillometric mean arterial pressure was higher than the recorded CW Doppler systolic pressure. In conclusion, the oscillometric method to determine systolic ankle pressure, based on the concept of maximum cuff oscillations occurring near mean arterial pressure, is not reliable in leg arterial disease, usually overestimating ankle pressure.     

Skin perfusion pressure measured by isotope washout in legs with arterial occlusive disease: Evaluation of different tracers,comparison to segmental systolic pressure,angiography and transcutaneous oxygen tension and variations during changes in systemic blood pressure

Summary. The skin perfusion pressure (SPP) measured as the isotope washout cessation external pressure is valuable in selection of major amputation level. Five methodological investigations important to clinical use were carried out: (1) In five normal legs and 10 legs with arterial occlusive disease (AOD), ¹³¹I-antipyrine (¹³¹1-_-a.p.) was compared to Na(¹³¹I-) and ⁹⁹Tc_m-I pertechnetate (⁹⁹Tc^m). The average SPP by ¹³¹I-_a.p. and by ¹³¹I- were approximately equal, 57·0 mmHg (range 18–93) compared to 56·3 mmHg (range 13–88) (P > 0·1). The average SPP by ⁹⁹Tc_m was just slightly higher, 60·3 mmHg (range 18–98) (P < 0·02). The average washout constant for the three different tracers were approximately equal and correlated statistically significant with the SPP; (2) In 59 legs with AOD, segmental SPP was compared to segmental systolic blood pressures on the thigh, calf, ankle and first digit (strain gauge technique). The two different methods correlated statistically significant at all four levels, but the systolic blood pressures were higher than the SPP in particular in diabetic legs; (3) Angiograms in 35 legs with AOD showed that the SPP on the ankle was only consistently decreased in legs with arterial occlusions at two levels or more; (4) In 47 legs with AOD, the SPP on the calf or on the thigh was compared with transcutaneously measured PO₂. The two different methods correlated statistically significant, but the scatter was great; (5) During induced variations in systemic blood pressure in seven patients (12 legs with AOD), the segmental SPP and the segmental systolic blood pressure were found on average to vary in proportion with the intra-arterial mean and systolic pressure respectively; however, this proportional relationship was not valid for the individual leg. It is concluded that ⁹⁹Tc^mis as suitable as the ¹³¹I-labelled tracers in estimating the SPP. The SPP is significantly correlated to skin blood flow, to systolic blood pressure, to tc PO₂ and to angiographic findings. Correction of SPP for systemic blood pressure changes can be made in proportion with the measured variations in systemic mean blood pressure. but only for groups of patients.     

A pitfall in the measurement of arterial blood pressure in the ischaemic limb during elevation

In order to evaluate if elevation of the ischaemic limb above heart level is an alternative to the conventionally applied method with external counterpressure for estimation of skin perfusion pressure, femoral and popliteal artery pressures were measured directly in eight patients with occlusion of the superficial femoral artery. The measurements were done in the horizontal position and during elevation of the calf above heart level. During elevation relative blood flow, measured by arterio-venous oxygen saturation differences, decreased compared with the horizontal position. In contrast the popliteal arterial pressure decreased only by 20% of the value expected from the degree of elevation of the calf above the level of the heart. Thus, it could be calculated that calf vascular resistance increased two- to three-fold on average during elevation. Four patients were reexamined with the venous pressure kept at 10 mmHg during elevation. In these patients, the increase in vascular resistance was significantly less compared with the situation in which venous pressure was 0 mmHg during elevation. The arterial pressure still did not decrease. It is concluded that perfusion pressure in the ischaemic lower extremity cannot be determined non-invasively by elevation of the extremity, probably due to collapse of segments of the vascular bed increasing the vascular resistance considerably.     

Treatment of severe foot ischaemia by defibrination with ancrod: a randomized blind study.

Forty-two patients, mean age 68 years, with severe leg ischaemia were randomly treated with placebo or by controlled defibrination with ancrod for 3 weeks. Plasma fibrinogen concentration was kept at about 20% of normal in the ancrod treated group. The two groups proved to be well matched regarding factors which could affect the degree of ischaemia. Objective measurements showed a significant rise in ankle and toe systolic blood pressure in the ancrod group lasting for 3 months. There was no rise in distal blood pressure in the control group. In the ancrod treated group the toe and ankle systolic pressures rose about 8 mmHg, but this was not accompanied by an improvement in the clinical course.     

The case for intermittent pneumatic compression of the lower extremity as a novel treatment in arterial claudication

Appreciation of the physiologic role of the natural muscle pumps of the lower limb in enhancing the return of venous blood promoted the development of intermittent pneumatic limb compression (IPC) systems that could activate these pumps artificially. The application of IPC to the foot (IPC(foot)), calf (IPC(calf)) or both (IPC(foot + calf)) on dependency generates a significant acute arterial leg inflow enhancement in patients with intermittent claudication that is highest with IPC(foot + calf), followed by IPC(calf) and IPC(foot). This enhancement is attributable to the leg venous pressure decrease after venous expulsion with IPC, which results in arteriovenous pressure elevation, and a marked attenuation in peripheral resistance to flow due to a transient abolition of peripheral sympathetic autoregulation and the release of nitric oxide. Implementation of IPC(foot) and IPC(foot + calf) for 3 to 5 months (> or = 2.5 hours/day) has been shown to improve the walking capacity and the ankle pressure indices of patients with intermittent claudication, with a significant beneficial impact on the quality of life. As the prevalence of symptomatic peripheral arterial disease is projected to increase substantially over the next decades with the aging population in Western societies and in the absence of established, cost-effective methods of treatment for claudication, the reported efficacy of IPC in claudication certainly warrants clinical attention. Level-1 clinical evidence by three independent investigators supports the clinical role of IPC in arterial claudication, reinforced by its domiciliary applicability, the high patient compliance with which it is associated, and the modest cost. This review offers an insight into the hemodynamic and clinical effects of IPC in patients with claudication in relation to the physiologic mechanisms proposed in explanation of these effects.     

Pain reduction interventions during neonatal circumcision

The purpose of this study was to determine the effect of some noninvasive pain reduction interventions on pain in 121 neonates undergoing unanesthetized circumcision. Subjects were randomly assigned to one of six groups: classical music, intrauterine sounds, pacifier, music and pacifier, intrauterine sounds and pacifier, or control (no nurses present and no pain reduction interventions used). Physiological variables that were monitored were heart rate, rhythm, dysrhythmias, blood pressure, transcutaneous oxygen (tcpO2), rate pressure product, and behavioral state, measured during 14 circumcision steps. Over the 14 steps, 42% of the heart rates, 78% of the systolic blood pressures (SBP), 30% of the diastolic blood pressures (DBP), and 81% of the tcpO2 pressures were abnormal. Few significant differences were found among any of the steps. SBP and DBP differed significantly between groups during two of the noninvasive steps; and tcpO2 differed significantly during six steps.     

Non-invasive estimates of aortic root pressures: external subclavian arterial pulse tracing calibrated by oscillometrically determined brachial arterial pressures,

Summary. This investigation assessed the ability of a non-invasive method to reproduce aortic root pressure waveform and pressures. An external pulse tracing of the subclavian artery was obtained simultaneously with direct aortic root pressures during routine left heart catheterization in 26 patients (aged 39–74 years) with various cardiovascular disorders. Indirect brachial arterial peak-systolic and nadir-diastolic pressures were obtained with oscillometry. The direct and indirect peak-systolic and nadir-diastolic pressures, were separately used to calibrate the pulse tracing. Adequate pulse tracing was obtained in 19 patients (73%). The waveforms agreed well with cross-correlation coefficients for systole and diastole of 0.98. The difference between the pulse trace and the direct pressure curve, when the first was calibrated with the peak-systolic and nadir-diastolic pressures of the latter on average was less than 1 mmHg for systole and diastole. At end-systole the mean difference was 5 mmHg. Oscillometric brachial arterial peak-systolic pressures were (meanSD) 37 mmHg below the corresponding direct measurements, while diastolic pressures were 84 mmHg above. The difference between the pulse trace and the direct pressure curve, when the pulse trace was calibrated with oscillometric pressures, was at end-systole 66 mmHg and for mean arterial pressures 54 mmHg. Thus, the external subclavian arterial pulse tracing provides a non-invasive, clinically feasible access to the aortic root pressure waveform. With optimal calibration, good estimates of aortic root pressures throughout systole and diastole can be obtained, while end-systolic pressure tends to be slightly overestimated.     

Effect of arterial revascularization on transcutaneous oxygen tension of the ischemic extremity

In 20 patients (24 limbs) with peripheral occlusive arterial disease involving the lower extremities, foot and chest transcutaneous oxygen tension (tcPO2) and ankle and arm systolic blood pressures were measured, with the patient's legs horizontal and with them in an elevated position, before and after revascularization procedures. Eighteen of the procedures were unilateral and were performed to alleviate severe ischemia; the three bilateral procedures were done to relieve intermittent claudication. Regional perfusion index (RPI) was calculated for each foot (RPI = tcPO2 foot/tcPO2 chest) with the legs horizontal and with the legs elevated for 3 minutes (RPI3). The ankle/brachial index was calculated from ankle and arm systolic blood pressures. Limbs with severe ischemia had considerably decreased RPI and RPI3 before revascularization, whereas limbs affected by claudication had only a modest decrease in RPI but a pronounced decrease in RPI3. The tcPO2, RPI, and RPI3 increased substantially after revascularization.     

Pain in chronic arterial occlusive disease--the effect of improved macrocirculation on pseudo-radicular irritation]

In chronic obliterating arteriopathy the maximum walking distance does not correlate well with the ankle arm index of arterial pressure measured by Doppler ultrasound. Beside reduced macrocirculation and microcirculatory maldistribution in skeletal muscle, pseudoradicular irritation was established as a relevant factor for the onset of pain during walking. The present study investigates the influence of the macrocirculation on hyperalgesia at rest in intermittent claudication. In 35 patients with chronic obliterating arteriopathy of the lower limbs (stage II according to Fontaine) the ankle/arm index of arterial pressure and the walking tolerance, as well as the pain at rest on applying pressure to the calf muscles were determined before and 3 weeks after percutaneous transluminar angioplasty (PTA). All 3 parameters improved after dilatation. Improved macrocirculation leads not only to a decreased production and improved clearance of pain-inducing metabolites in muscle tissue, but also--through a decrease of sympathetic stimulation of the muscle--to an elevation of the pain threshold. Apart from the reduction in pain-inducing metabolites, an absence of booster effects on pseudoradicular irritation and the regeneration of sensitive cutaneous afferents with resultant inhibition of reflex pain development are considered as possible factors in the achievement of pain relief following PTA.     

Selectivity of superficial vein occlusion at the ankle and calf level: a methodological study in healthy volunteers

Judgement of deep venous function may be necessary before surgery for superficial vein incompetence is performed. Assessment of deep venous function needs selective entrapment of superficial venous compartments between the ankle and knee, which may not be guaranteed if conventional tourniquets are used. This study was, therefore, aimed at modifying the technique of selective compression of superficial vein compartments. Twenty apparently normal legs of 10 volunteers were investigated on two study days. The subjects were in a supine position with the feet resting 30 cm above heart level. Ankle cuffs (3 cm wide) were placed just above the malleoli and stepwise inflated with air. The steady-state venous volume of the forefoot as a function of the pressure within the ankle cuff was measured with a mercury-in-rubber strain gauge. The maximum venous outflow velocity from the foot was also measured at each cuff pressure step after the addition of conventional thigh vein occlusion. The same protocol was used on the second study day: calf cuffs (3 cm wide) were then used instead of the ankle cuffs. In the forefoot, venous volume increased and the maximum venous outflow velocity decreased significantly either at ankle cuff pressures >30 mmHg or at calf cuff pressures of >60 mmHg. By using small cuffs, selective superficial vein occlusion seems to occur at cuff pressures ranging between 10 and 30 mmHg (ankle) and between 30 and 60 mmHg (calf), provided the feet are 30 cm above heart level. Higher cuff pressures seem to interact with deep venous function.     

Transcapillary forces in patients with lower limb ischemia

Starling pressures (interstitial fluid pressure, plasma and interstitial fluid colloid osmotic pressures) were measured in subcutaneous tissue at the ankle in 20 healthy controls and 27 patients with lower limb atherosclerosis. Subcutaneous interstitial fluid pressure (Pif) of the leg was also measured in seven patients with arterial emboli of the lower limb. Interstitial fluid was collected by implantation of nylon wicks and Pif was measured by the 'wick-in-needle', technique. The calculated reabsorption pressure (equal to capillary pressure if no net filtration occurs) was 18.3 mmHg in the group with atherosclerosis, which was higher than in controls (15.8 mmHg, P less than 0.05). Colloid osmotic pressure of interstitial fluid (COPif) was significantly lower in patients with atherosclerosis than in controls (5.9 v. 9.2 mmHg). This finding in itself could make those patients more susceptible to edema formation postoperatively. On the other hand, there was no correlation between COPif and ankle systolic blood pressure within the group of patients. There was a slight, but statistically significant positive correlation between ankle systolic blood pressure and Pif in patients with lower limb atherosclerosis although mean Pif was not different from controls (-1.0 v. -0.8 mmHg). In patients with arterial emboli, however, Pif was lower (mean -4.5 mmHg).     

Brachial blood pressure monitoring versus ankle monitoring during colonoscopy

OBJECTIVES: To compare ankle and brachial blood pressure monitoring before and during colonoscopy using automated noninvasive blood pressure (NIBP) monitors. METHODS: Forty-five consecutive patients who presented for outpatient colonoscopy had both ankle and brachial blood pressure monitoring with automated NIBP using an appropriately sized cuff for arm or leg size. Three baseline measurements were obtained, and then measurements were taken at 5-minute intervals during conscious sedation, with brachial blood pressure being the standard. RESULTS: The average of all of the ankle blood pressures was significantly higher for all systolic and mean arterial blood pressure readings. Diastolic blood pressure readings were higher at baseline, but not significantly different during the procedure. CONCLUSIONS: Ankle systolic and mean arterial blood pressures using automated NIBP monitoring for conscious sedation are significantly higher than brachial blood pressures. Ankle NIBP monitoring should only be used if brachial NIBP monitoring is not feasible, taking into consideration that ankle NIBP pressures are generally higher than brachial.     

Effects of two gravity inversion methods on heart rate, systolic brachial pressure, and ophthalmic artery pressure

The purpose of this study was to investigate the effects of two static gravity inversion methods with either ankle or thigh suspension on heart rate (HR), systolic brachial pressure (SBP), and ophthalmic artery pressure (OAP). Twenty healthy subjects were assigned randomly to one of two treatment groups of 10 subjects each. Each group completed a 25-minute protocol with two 5-minute inversion periods. The research attempted to control for treatment anxiety and for the effects of ocular plethysmography (the procedure used to measure OAP). A 2 X 2 multivariate analysis of variance for repeated measures was used to analyze the differences of cardiovascular change between the two inversion methods. The hypothesis that the subjects' HRs, SBPs, and OAPs would not differ between ankle and thigh suspension methods for five minutes of inversion was not rejected. Leg position did not affect the HR or arterial responses during full static inversion. Gravity inversion produced no significant changes in HR and SBP between 2.5 and 5 minutes of inversion. Arterial pressures measured at 5 minutes of static inversion did not differ from arterial pressures measured between 2.5 and 5 minutes, but because of increases in OAP during inversion, ocular safeguards are recommended for subjects during inversion.     

Redistribution of skin blood flow during leg dependency in peripheral arterial occlusive disease

Summary A disturbed autoregulation of cutaneous blood flow in legs with peripheral arterial occlusive disease (PAOD) has previously been demonstrated for circumscribed skin areas. In the present study, posturally-induced changes of skin perfusion distribution along ischaemic limbs were investigated topographically in 35 PAOD patients by means of fluorescein perfusography. Among the 68 legs studied, 7 had patent arteries and 61 could be assigned to FONTAINE stages I to IV. Limbs with peripheral skin lesions (stage IV) were further differentiated according to either healing (stage IV+) or non-healing (stage IV-) on conservative treatment. Sitting-up always led to prolonged calf as well as foot fluorescein appearance times (AT) except for legs in stage III or IV- disease. In the latter two groups, decreased sitting as compared to supine AT foot-to-calf ratios indicated a relative shift of dye delivery from proximal towards distal skin regions during posture. In contrast, this measure of blood flow redistribution did not change in the other groups. The redirection of fluorescein influx was significantly correlated with the systolic arterial pressure ankle-to-arm ratios. In conclusion, besides small perfusion pressure increases or passive microvessel distension, a shift of the peripheral resistance ratios may contribute to the improved blood supply of ischaemic skin regions during leg dependency. An arteriolar vasoparalysis does not regularly exist in limbs with skin lesions not primarily originating from ischaemia (stage IV+).     

Peripheral arterial circulation in individuals with impaired glucose tolerance

Employees of a telephone company in Naples (N = 1376) were screened by oral glucose tolerance test (OGTT, 75 g). All those with impaired glucose tolerance (IGT) (N = 69) plus 138 normoglycemic controls, matched by sex, age, and body mass index (BMI, kg/m2), were selected to participate in this study. All participants were retested by OGTT under the same conditions as the first test. The prevalence of signs of impaired peripheral arterial circulation (IPAC) were investigated by different methods: Rose questionnaire on intermittent claudication, digital pulse plethysmography (inclination time), and ankle blood pressure measurement (ankle/arm systolic blood pressure). Very few persons had symptoms of IPAC: 2 (3.1%) and 3 (2.4%), respectively, in IGT subjects and controls. No difference in the prevalence of abnormal vascular parameters was detected between IGT and normoglycemic individuals according to either digital pulse plethysmography (6.1% versus 8.8%, P = 0.36) or ankle blood pressure measurement (10.8% versus 9.6%, chi 2 = 0.06, NS); similar results were obtained when the prevalence of abnormalities was evaluated according to both methods combined (16.9% versus 16.8%). The finding remained very much the same after controlling for the effect of smoking. Individuals with IGT at both OGTTs were compared with individuals with normoglycemia at both tests: once again no significant difference was detected between the two groups in the prevalence of abnormal vascular findings (22.6% versus 16.7%, chi 2 = 0.66, NS). This suggests that IGT is not associated with increased prevalence of atherosclerotic peripheral arterial disease.     

Calf muscle stretching is ineffective in increasing ankle range of motion or reducing plantar pressures in people with diabetes and ankle equinus: A randomised controlled trial

BackgroundLimited ankle dorsiflexion, or equinus, is associated with elevated plantar pressures, which have been implicated in the development and non-healing of foot ulcer. A stretching intervention may increase ankle dorsiflexion and reduce plantar pressures in people with diabetes.MethodsTwo arm parallel randomised controlled trial from September 2016 to October 2017. Adults with diabetes and ankle equinus (≤5° dorsiflexion) were randomly allocated to receive an 8 week static calf stretching intervention or continue with their normal activities. Primary outcome measures were change in weight bearing and non-weight bearing ankle dorsiflexion and forefoot peak plantar pressure. Secondary outcome measures were forefoot pressure time integrals and adherence to the stretching intervention.Findings68 adults (mean (standard deviation) age and diabetes duration 67.4 (10.9) years and 14.0 (10.8) years, 64.7% male) were randomised to stretch (n = 34) or usual activity (n = 34). At follow up, no significant differences were seen between groups (adjusted mean difference) for non-weight (+1.3°, 95% CI:−0.3 to 2.9, p = 0.101) and weight bearing ankle dorsiflexion (+0.5°, 95% CI:−2.6 to 3.6, p = 0.743) or forefoot in-shoe (+1.5 kPa, 95% CI:−10.0 to 12.9, p = 0.803) or barefoot peak pressures (−19.1 kPa, 95% CI:−96.4 to 58.1, p = 0.628). Seven of the intervention group and two of the control group were lost to follow up.InterpretationOur data failed to show a statistically significant or clinically meaningful effect of static calf muscle stretching on ankle range of motion, or plantar pressures, in people with diabetes and ankle equinus.     

Comparison of non-invasive blood pressure monitoring using modified arterial applanation tonometry with intra-arterial measurement

Intermittent non-invasive blood pressure measurement with tourniquets is slow, can cause nerve and skin damage, and interferes with other measurements. Invasive measurement cannot be safely used in all conditions. Modified arterial tonometry may be an alternative for fast and continuous measurement. Our aim was to compare arterial tonometry sensor (BPro^®) with invasive blood pressure measurement to clarify whether it could be utilized in the postoperative setting. 28 patients who underwent elective surgery requiring arterial cannulation were analyzed. Patients were monitored post-operatively for 2 h with standard invasive monitoring and with a study device comprising an arterial tonometry sensor (BPro^®) added with a three-dimensional accelerometer to investigate the potential impact of movement. Recordings were collected electronically. The results revealed inaccurate readings in method comparison between the devices based on recommendations by Association for the Advancement of Medical Instrumentation (AAMI). On a Bland–Altman plot, the bias and precision between these two methods was 19.8?±?16.7 (Limits of agreement ??20.1 to 59.6) mmHg, Spearman correlation coefficient r?=?0.61. For diastolic pressure, the difference was 4.8?±?7.7 (LoA ??14.1 to 23.6) mmHg (r?=?0.72), and for mean arterial pressure it was 11.18?±?11.1 (LoA ??12.1 to 34.2) mmHg (r?=?0.642). Our study revealed inaccurate agreement (AAMI) between the two methods when measuring systolic and mean blood pressures during post-operative care. The readings for diastolic pressures were inside the limits recommended by AAMI. Movement increased the failure rate significantly (p?<?0.001). Thus, arterial tonometry is not an appropriate replacement for invasive blood pressure measurement in these patients.     

Evaluation of an isotope washout technique to measure skin vascular resistance and skin perfusion pressure: influence of age, site and arterial surgery

A simplified isotope washout technique has been devised to calculate the skin perfusion pressure (SPP) and skin vascular resistance (SVR). This test is simple, requires inexpensive equipment and is well tolerated by patients. SPP and SVR were calculated in 20 patients less than 30 years of age, 13 patients greater than 30 years of age and in 15 patients with peripheral vascular disease (PVD). With increasing age the SPP and SVR were increased. The SPP was similar to the mean arterial pressure in normal individuals but was decreased in patients with PVD. The SPP is a useful indicator of the severity of the PVD. The SPP and SVR were higher in the calf than in the foot. This is probably related to the decrease in pressure in the distal arterial tree. SPP was increased by 110% and skin blood flow by 190% by arterial reconstructive surgery. This test may be of use in assessing the effectiveness of arterial surgery.