A device for noninvasive assessment of perfusion pressure in the skin of healthy volunteers

A device allowing pressure to be applied to a local skin site where the skin blood flow is followed using laser Doppler flowmetry is described. The blood flow was studied on the back of the hand in eight volunteers before and during brachial arterial occlusion and while the external pressure was increased step by step. The flowmetry value during arterial occlusion was 0.3 +/- 0.1 AU, and when the external pressure was increased to 120 mm Hg the values were similar (p = .44). The skin perfusion pressure, defined as the least external pressure needed to achieve flow cessation, was found to be 92 +/- 16 mm Hg (range 70-111 mm Hg), and the mean arterial pressure was 90 +/- 9 mm Hg (NS). The skin perfusion value is in agreement with that found by others using other techniques for measuring blood flow and a circumferent cuff for applying pressure.     

The correlation between three methods of skin perfusion pressure measurement: radionuclide washout, laser Doppler flow, and photoplethysmography.

The most accurate measurement of skin perfusion pressure is made with use of radioisotopic clearance techniques. We compared the skin perfusion pressure using radioisotope to the skin perfusion pressure measured simultaneously by placing laser Doppler and photoplethysmography probes within a transparent polyvinylchloride plastic blood pressure cuff in 13 subjects. A new device, which was created for this experiment, consisted of a plastic bladder into which light-emitting probes can be placed, so that the pressure applied to the skin was transmitted by the surface of the bladder, rather than by the surface of a rigid probe. The cuff was inflated to a supra-systolic pressure over the intradermal injection site of technetium Tc 99m, then deflated in 10 mm Hg decrements at 3-minute intervals. The pressures at which radioisotope clearance began, at which microcirculatory flow was detected by laser Doppler, and at which deflection of the photoplethysmography (DC mode) output occurred, were recorded as the skin perfusion pressure. The range of radioisotopic determined skin perfusion pressure was 0 to 100; skin perfusion pressure-laser Doppler was 0 to 100; and skin perfusion pressure-photoplethysmography was 60 to 100, with 7 of 13 limbs demonstrating no clear deflection point and thus an unobtainable skin perfusion pressure-photoplethysmography reading. Linear regression revealed a coefficient of correlation of 0.991 for skin perfusion pressure when the radioisotopic and laser Doppler methods were compared. Our study is not in agreement with previous reports of the successful determination of skin perfusion pressure with use of photoplethysmography. This may be due to differences in our technique when compared with previous reports of skin perfusion pressure-photoplethysmography determination.(ABSTRACT TRUNCATED AT 250 WORDS)     

New algorithm for oscillometric noninvasive automatic arterial pressure measurement in patients with atrial fibrillation

Oscillometric noninvasive arterial pressure monitoring devices frequently fail to measure pressure precisely in patients with arrhythmia, such as atrial fibrillation, because beat-by-beat changes in pulse pressure and mean pressure level distort the relation between cuff pressure and oscillometric wave amplitude. To overcome this problem, we developed a new algorithm for oscillometric measurement in which oscillometric wave amplitude is corrected according to changes in pulse pressure and mean arterial pressure level. In 7 patients with atrial fibrillation, we compared systolic pressure thus estimated with that simultaneously measured invasively in the radial artery and averaged during oscillometric measurement. Correction based on invasively obtained beat-by-beat pulse pressure and mean pressure level decreased the ratio of unmeasurable cases from 11 to 4%. Correction based on plethysmographically estimated pulse pressure decreased unmeasurable cases to 6% (P < 0.01). Standard error of systolic pressure estimates was 6.44 +/- 1.83, 4.10 +/- 0.85, and 4.75 +/- 1.26 mmHg with no, invasive, and plethysmographical correction in this order (P < 0.01). We conclude that oscillometric wave amplitude correction based on beat-by-beat pulse pressure and mean arterial pressure level lessened the number of unmeasurable cases and improved measurement precision in patients with atrial fibrillation.     

Utility of perioperative skin perfusion pressure measurement for treatment of ulcers caused by arteriovenous access ischaemic steal

Arteriovenous access ischaemic steal is a serious complication following arteriovenous fistula (AVF) construction. The aim of treatment is to improve distal circulation without impairing the function of the fistula. Therefore, any repair should be performed with intraoperative monitoring. We report 2 cases of this disorder treated using perioperative measurement of skin perfusion pressure (SPP) for preoperative surgical planning and intraoperative guidance. A 73‐year‐old woman with a left cubital AVF developed gangrene of the tip of the left little finger. Arteriovenous access ischaemic steal was suspected. The SPP of the little finger was 18 mm Hg, which increased to 65 mm Hg after manual occlusion of the fistula. A 58‐year‐old woman with a left antebrachial AVF had gangrene of the tip of the left middle finger. The SPP was 19 mm Hg, and steal syndrome was suspected based on angiography and the SPP with manual occlusion of the fistula. In both cases, serial plication of the fistula was performed based on intraoperative perfusion pressure monitoring, leading to the successful resolution of the ischaemic steal syndrome. In both cases, haemodialysis could be continued through the repaired fistula.     

连续无创血压监测系统在产科麻醉的应用

目的探讨连续无创血压监测系统(CNAP)CNAP~(TM)monitor 500比较传统的无创袖带血压(NIBP)监测系统应用于腰硬联合麻醉后剖宫产监测低血压发生的时效性。方法选择85例产妇在腰硬联合麻醉下行剖宫产术。总共有1040对产妇的收缩压和舒张压被监测,间隔周期为3 min,观察时间为麻醉前到胎儿娩出后,并记录新生儿的脐静脉血气分析和Apgar评分。结果相比NIBP,每一周期CNAP能监测的最低收缩压平均值(103±20.6 mmHg)明显低于(P0.05)NIBP的平均值(116±17.9 mmHg)和最高的CNAP收缩压平均值(120±19.6 mmHg)。低血压定义为收缩压低于90 mmHg,CNAP监测组低血压的发生率70.58%,而NIBP监测组低血压的发生率为35.29%。当CNAP监测的低血压(收缩压为90 mmHg)时,未发现胎儿酸中毒(脐静脉血p H值7.25)。结论 CNAP能够比NIBP监测出更多的低血压事件,而且动脉血压明显低于NIBP监测系统。从胎儿利益的角度出发,CNAP的监测比NIBP更适于需要腰硬联合的产科手术。     

Novel imaging methods reveal positive impact of topical negative pressure application on tissue perfusion in an in vivo skin model

The influence of topical negative pressure application (TNPA) on tissue perfusion still remains controversial. TNPA was applied for 30 minutes on intact skin of 21 healthy participants. Measurements of tissue oxygen saturation and tissue temperature as signs of tissue perfusion were performed before application of the TNPA, directly after removal of the TNPA and 5, 10, 15, 20, and 30 minutes after removal of the dressing using the near infrared imaging (NIRI) and a thermal imaging camera. Tissue oxygen saturation showed an increase from 67.7% before applying the TNPA to 76.1% directly after removal of TNPA, followed by a decrease of oxygen saturation 30 minutes after removal of TNPA. The measured temperature of the treated skin area increased from 32.1°C to 36.1°C after removal of TNPA with a consecutive decrease of the temperature 30 minutes after removal. TNPA resulted in both a higher tissue oxygen saturation and a higher skin temperature after 30 minutes compared to the beginning. TNPA increases both tissue oxygen saturation and skin temperature as sign of an increase of tissue perfusion. NIRI and thermal imaging proved to be useful for measuring changes in tissue perfusion.     

aFGF透皮给药治疗缺血皮瓣的临床应用

目的:观察酸性成纤维细胞生长因子(aFGF)透皮给药治疗反流轴型皮瓣血液循环障碍的疗效.方法:应用aFGF透皮给药治疗出现血液循环障碍的反流轴型皮瓣,观察皮瓣的转归.结果:自2006年以来在临床上应用11例,用药后皮瓣血液循环全部得到明显改善,存活良好.结论:应用aFGF透皮给药可明显改善反流轴型皮瓣的血液灌流,促进皮瓣成活.     

Noninvasive determination of skin perfusion pressure using a laser Doppler

Laser Doppler (LD) measures blood flow in approximately one cubic millimeter of tissue. The LD instrument is well suited to the determination of the initiation of flow in the microcirculation after a period of arrest due to externally applied counterpressure. Radioisotope clearance and photoplethysmography have been used to measure skin perfusion pressure (SPP) in an effort to predict healing of ischemic ulcerations and amputation wounds. By placing the LD probe beneath a blood pressure cuff, SPP was measured at the forearm, thigh, calf, foot, dorsal and plantar great toe. The SPP was measured in 32 normal limbs and 26 limbs with rest pain, ulceration or gangrene. Skin of normal extremities and forearm and thigh skin of patients with ischemic lower extremities had a mean SPP of 47 mmHg (+/- 5 SEM). The SPP in ischemic extremities was significantly lower at the calf 22 +/- 4 (p less than .001), the foot 10 +/- 2 (p less than .0001), and the toe 16 +/- 4 (p less than .0001). SPP was greater at the plantar toe (73 +/- 5) than in all other locations. Skin of the plantar toe was unique among the sites measured because it is rich in arteriovenous anastomoses, which have a thermoregulatory function. The higher pressure probably reflects the fact that the larger arterioles have a higher intraluminal pressure than the capillaries and, therefore, a more proximal level of the microcirculation is measured by the LD instrument in thermoregulatory areas of the skin.(ABSTRACT TRUNCATED AT 250 WORDS)     

配合尿道灌注治疗男性支原体性尿道炎

目的 观察配合尿道灌注治疗男性支原体性尿道炎的疗效。方法 将530例患者随机分为4组。A组：尿道灌注组；B组：静脉给药组；C组：上述两种方法并用；D组：C组的基础上，加用紫苓胶囊。结果 A组与B组间总有效率差异无显著性（P〉0．05）；C组与D组总有效率高于A组与B组（P〈0．05）；C组与D组间总有效率差异无显著性（P〉0．05），在复查支原体阴性患者中，D组治愈率高于C组（P〈0．05）。结论 阿奇霉素尿道灌注与静点疗效相同，联合用药可提高疗效，紫苓胶囊可以改善不适症状。     

Modeling of bioheat equation for skin and a preliminary study on a noninvasive diagnostic method for skin burn wounds

Heat transfer in a unit three-dimensional skin tissue with an embedded vascular system of actual histology structure is computed in the present work. The tissue temperature and the blood temperatures in artery and vein vessels are solved with a multi-grid system. The mean temperature of the tissue over the cross-section of the unit skin area is evaluated. The resulting one-dimensional function is regarded as the temperature of healthy tissue (or injured skin but the blood perfusion is still normally working) for large area of skin in view of the symmetric and periodic structure of the paired artery–vein vessels in nature. A three-dimensional bioheat equation then is formulated by the superposition of the skin burn wound effect and the healthy skin temperature with and without thermal radiation exposure. When this bioheat equation is employed to simulate ADT process on burn wounds, the decaying factor of the skin surface temperature is found to be a sharply decreasing function of time in the self-cooling stage after a thermal radiation heating. Nevertheless, the boundary of non-healing (needing surgery) and healing regions in a large burn wound can be estimated by tracking the peak of the gradient of decaying factor within 30 s after the thermal radiation is turned off. Experimental studies on the full ADT procedure are needed to justify the assumptions in the present computation.     

Laser Doppler skin perfusion pressure in the assessment of Raynaud's phenomenon.

OBJECTIVES: In the assessment of Raynaud's phenomenon, objective evaluation of digital microcirculatory flow is important, and so we investigated whether the measurement of laser Doppler skin perfusion pressure could be of use. MATERIALS AND METHODS: Ten fingers of five patients with secondary Raynaud's phenomenon due to systemic sclerosis, 22 fingers of 11 patients with primary Raynaud's phenomenon and 10 fingers of five control patients were examined. Skin perfusion pressure was measured on the third finger of both hands at rest, and then again 3 min after local cold exposure. RESULTS: Laser Doppler skin perfusion pressure at rest in patients with secondary Raynaud's phenomenon was significantly lower than that in patients with primary Raynaud's phenomenon and the control patients (p<0.05). Skin perfusion pressure decreased significantly in both patient groups upon local cold exposure (p=0.005). There were significant differences in perfusion pressure after cold exposure among both groups (p<0.05). CONCLUSIONS: The low skin perfusion pressure at rest in patients with secondary Raynaud's phenomenon suggested the presence of obstructive arterial lesions. The marked pressure decrease in all Raynaud's patients after local cold exposure might be due to vasospasm of the microvasculature in the digits. These results indicate that the measurement of laser Doppler skin perfusion pressure is valuable in the diagnosis of Raynaud's phenomenon.     

Wound healing in above-knee amputations in relation to skin perfusion pressure.

In 59 above-knee amputations healing of the stumps was correlated with the local skin perfusion pressure (SPP) measured preoperatively as the external pressure required to stop isotope washout using 1318-- or 125I--antipyrine mixed with histamine. Out of the 11 cases with an SPP below 30 mmHg no less than nine (82 per cent) suffered severe wound complications. Out of the 48 cases with an SPP above 30 mmHg severe wound complications occurred in only four cases (8 per cent). The difference in wound complication rate is highly significant (P less than 0.01). The postoperative SPP measured on the stumps was on average only slightly and insignificantly higher than the preoperative values, explaining why the preoperative values related so closely to the postoperative clinical course. We conclude that the SPP can be used to predict ischaemic wound complications in above-knee amputations as has previously been shown to be the case in below-knee amputations.     

Blood pressure measurement in volunteers with and without padding between the cuff and the skin

Automated non-invasive arterial blood pressure measurements are made frequently during anaesthesia. Conscious patients often find the measurement uncomfortable. The tissues under the cuff can suffer trauma such as skin creasing, blistering, petechial haemorrhages and even nerve damage. We placed soft padding between the blood pressure measurement cuff and the skin of the upper arm of 140 healthy volunteers, and compared cuff-related skin trauma and arterial blood pressure measurements with and without the padding. Padding was associated with a significant reduction in the frequency and intensity of skin trauma (p < 0.0001). There was no significant overall effect of the presence of padding on arterial blood pressure readings. We conclude that the benefit of padding outweighs any compromise to the reliability of arterial blood pressure measurement.     

Knee range of motion: reliability and agreement of 3 measurement methods

We conducted a study to compare 3 methods of measuring knee range of motion: visual estimation by physicians, hand goniometry by physical therapists, and radiographic goniometry. We hypothesized that reliability would be high within and across all techniques. We found intrarater and interrater reliability to be satisfactory for visual estimation, hand goniometry, and radiographic goniometry. Interrater reliability across methods did not agree satisfactorily. Between-methods differences in estimating knee range of motion may result from variations in technique among physicians and physical therapists.     

Continuous flow cystometry and urethral pressure profile measurement with monitored intravesical pressure: A diagnostic and prognostic investigation

Summary A technique is described for continous flow cystometry and urethral pressure profile measurement with monitored intravesical pressure. This is considered to be a reliable and valuable procedure for the investigation of detrusor and closure mechanism disorders. The urethral profile has two components, the intraurethral pressure and the functioning length. Different bladder volumes have been shown to affect the urethral profile. The normal urethra may respond to maximum bladder volume by increasing its profile components. Patients with incontinence due to defects of the closure mechanism show a decrease in these measurements at maximum bladder volume or a subnormal profile at both volumes. These findings have provided a prognostic index for the use of electronic stimulators for the control of incontinence.     

The effect of different positions on lower limbs skin perfusion pressure

We have encountered situations of patients with critical limb ischemia accompanied by pain at rest and necrosis, who hang their legs down from the bed during sleep. This lower limb position is known to be a natural position, which reduces pain in the lower extremity induced by ischemia. However, the effect of this position on blood flow of the lower extremity is poorly understood. We studied whether measurements of skin perfusion pressure (SPP) changes by leg position and the difference between healthy adults and patients with critical limb ischemia. The subjects of this study were 10 healthy adults and 11 patients with critical limb ischemia. Patients with critical limb ischemia, including both dorsum of foot and plantar of foot, having SPP of lower limbs of less than 40 mmHg (supine position) were the object of this study. SPP was measured on four positions (supine position, lower limbs elevation position, sitting position, and reclining bed elevation of 20^° position). In sitting position, both the number of healthy adults and critical patients show significant increases in SPP compared with the other three positions. These results suggest that sitting position is effective to keep good blood stream of lower limbs not only in healthy adults but also in patients with critical limb ischemia. However, an appropriate leg position should not have lower limbs hang downwards for long periods time because edema is caused by the fall in venous return in lower limbs, and the wound healing is prolonged.Our clinical research could be more useful in the future, particularly in developing countries, for surgeons managing wounds in leg and foot and preserving ischemic limbs.KEY WORDS: Critical limb ischemia, peripheral arterial disease, position, skin perfusion pressure     

简易持续恒压自控皮肤扩张器的临床应用

目的　探讨一种自制、简单易行的持续恒压全封闭式自控皮肤扩张器的疗效。方法　用一次性输液器、医用三通、软装储水瓶(囊)、生理盐水充注式乳房假体的注水导管与普通去注射壶扩张器装配成全封闭式持续注水系统,用充气式加压输液器及普通弹簧式血压计组成持续恒压系统,将软装储水瓶(囊)放置于充气加压输液器内,通过挤压皮球加压,将软装储水瓶(囊)中液体注入扩张器中,据患者痛阈值设置注水压力,由其自行注水及调节压力。临床应用 20 例 26 个扩张器,扩张容量为 100~400 ml,术后3~5 d开始注水,达所需扩张面积后停止注水。结果　注水量为120~640 ml,注水时间为10~16 d,平均(13.6±2.1) d,无并发症发生。结论　简易持续恒压自控全封闭式注水扩张器, 具有取材制作方便、操作简单易行、扩张速度快、安全可靠、高效、佩戴舒适的特点,值得推广。