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he effects of leg/body position onranscutaneous oxygen measurements afterower-extremity arterial revascularizationathleen Rich, PhD, RN, CCNS

A postoperative nursing goal in a patient with peripheral artery disease requiring lower-extremity arterial recon-struction surgery is to maintain blood flow and tissue oxygenation to the revascularized extremity. This may be achievedthrough extremity positioning. Transcutaneous oxygen (TcPO2) measurements provide a noninvasive objective determi-nation of oxygen at the skin surface and assessment of underlying circulation and tissue oxygenation. The purpose of thisstudy was to determine which lower-extremity position afforded the highest TcPO2 in 10 subjects with a lower-extremityarterial revascularization procedure preoperatively and 24 and 48 hours postoperatively. Hypotheses included compar-ing preoperative and postoperative TcPO2 measurements, leg skin temperatures, and limb volumes. The subjects werestudied in three different leg/body positions: supine with legs extended, sitting with legs extended, and supine withlegs-elevated 20 degrees using the Radiometer TCM30 (Radiometer; Copenhagen) and PhysitempTH-5 Thermalert(Physitemp; Clifton, NJ) monitors. There was no change in the postoperative leg TcPO2 measurements or limb volumescompared with preoperative measurements (P � .12-.92). A small sample size and lack of peripheral artery diseasestratification were among study limitations. Significant to the nursing care of patients with vascular dsease is the findingthat any of the leg/body positions in this study could be used postoperatively on the revascularized extremity without

decreasing TcPO2 measurements. (J Vasc Nurs 2008;26:6-14)

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Peripheral arterial disease (PAD) occurs in 12% to 20% ofersons aged more than 65 years in the United States.1 Approx-mately 20% of individuals with intermittent claudication willave progression of the disease requiring a revascularizationrocedure in 10 years to restore arterial blood flow and preventimb loss.2 In a surgical revascularization, the physician’s goal iso restore arterial blood flow and tissue oxygenation to theschemic limb. The nursing goal is to maintain blood flow andissue oxygenation to the revascularized extremity. Nursingchieves this goal by monitoring the neurovascular status of theower extremity and by altering the extremity position.

ROBLEM STATEMENT

Extremity positioning is a method by which nursing assists aatient in maintaining optimal circulation and oxygenation. Nursesrequently position the leg after a patient has undergone a lower-xtremity arterial revascularization surgery. There are differingecommendations in various nursing references relative to the

From the La Porte Regional Health System, La Porte, Indiana.

Support for this study was provided by the Society for VascularNursing and Radiometer America, Inc.

Corresponding author: Kathleen Rich, PhD, RN, CCNS, Cardio-vascular Clinical Specialist, La Porte Regional Health System,1007 Lincolnway, La Porte, IN 46350.

1062-0303/2008/$34.00

Copyright © 2008 by the Society for Vascular Nursing, Inc.

doi:10.1016/j.jvn.2007.09.002

ostoperative leg position. Nettina and Mills3 and Lewis4 advo-ate extremity elevation as a standard. Fahey and Schindler5

ecommend limb elevation when postoperative edema is present.onayne6 advises to position the extremity for optimal circula-

ion, but does not provide any specifics.Objectively evaluating the effect of the position changes on

irculation and tissue oxygenation may be established throughhe use of transcutaneous oxygen (TcPO2) measurements. TcPO2

easurements provide a noninvasive determination of the trans-ermal (skin) oxygen diffusion from the superficial nutritive skinapillaries. This offers a means of estimating the underlying circu-ation and tissue oxygenation. The objective determination re-arding the effect of extremity position through the use of TcPO2

easurements may provide quantitative evidence to support theursing practice and lend validity to the nursing care delivered.

URPOSE/AIMS/HYPOTHESES

The purpose of this study was to determine which lower-xtremity position afforded the highest TcPO2 measurement inatients who have undergone a lower-extremity arterial revas-ularization procedure. The study evaluated the lower-extremitycPO2 measurements in subjects with PAD, both men andomen, preoperatively and 24 and 48 hours after an arterial

evascularization surgical procedure with the lower extremity inhree different positions. The following hypotheses were tested.

ypothesis 1: Skin temperature on the lower extremity will belower preoperatively in the subjects with PAD compared

with 24 and 48 hours postoperatively.

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ypothesis 2: The skin oxygen on the lower extremity will belower preoperatively in the subjects with PAD comparedwith 24 and 48 hours postoperatively.

ypothesis 3: Preoperative lower-extremity limb volume in thesubjects with PAD will not be different compared with thelower-extremity limb volume 24 and 48 hours postoperatively.

EFINITION OF TERMS

Skin oxygen is the transdermal (skin) oxygen diffusion fromhe superficial nutritive skin capillaries. Skin oxygen is indirectlyetermined by the noninvasive technique of TcPO2 measure-ents that obtain the partial pressure of O2 at the epidermal

skin) surface. A normal adult extremity TcPO2 value has beeneported to be 60 mm Hg.7 In adults, the TcPO2/PaO2 relation-hip is approximately 0.80.8

EVIEW OF LITERATURE

In adults with PAD, TcPO2 measurements have been studiedo identify and quantify the presence and severity of the disease.urther indications for TcPO2 measurements have includedhronic venous disease, evaluating the status of extremityounds and as a demarcation reference point for amputations.9

he addition of supplemental oxygen and extremity positioninganeuvers are used to elicit subtle disease variations.

Multiple researchers have conclusively found that individu-ls with PAD had a lower TcPO2 measurement in the involvedxtremities when compared with healthy persons while atest.10-12 Attempts to correlate the severity of PAD by Fontainetages and TcPO2 results were more accurate in Stage IV inhich TcPO2 values of less than 30 mm Hg had a sensitivity of1% and a specificity of 91%.13 Fontaine Stages II and IIIesearch results were mixed. Studies using exercise testing whileeasuring the TcPO2 values found a significant decrease incPO2 during and after exercise in the subjects with PAD,hereas the healthy subjects had no change.14-16

Research on wounds has attempted to determine the TcPO2

easurements that are predictive of healing. A generalizedonsensus is an impaired ability of wounds to heal when theoom air TcPO2 value is less than 40 mm Hg. If the woundcPO2 is less than 20 mm Hg, primary wound healing did notccur.7 The use of supplemental oxygen as a diagnostic adjunctn predicting wound healing improved the outcome determina-ion with a TcPO2 increase of 10 mm Hg during 100% oxygeneing a positive predictor of healing.17 Two separate studiesound TcPO2 increases greater than 50 mm Hg and 100 mm Hguring hyperbaric therapy were positive healing indicators.18,19

Positional maneuvers of the lower extremity were adjuncts inbtaining TcPO2 measurements patients with PAD. Studies haveeported in both healthy individuals and patients with PAD; depen-ent leg positions increased TcPO2, whereas elevating the legs at0 degrees decreased the TcPO2 when compared with the supineosition.20-23 Scheffler et al.24 proposed if the supine lower-xtremity TcPO2 value was less than 10 mm Hg or the sittingcPO2 was less than 45 mm Hg, it could be assumed that aritical ischemia exists.

Individuals with a revascularized lower extremity were sub-

ects in several TcPO2 research studies. Osmundson et al.25 o

eported an improvement in revascularized limbs using 30-egree leg-elevated and supine positions in 20 patients 1 weekfter surgery compared with preoperatively. A study by Moosat al.26 noted an improvement in leg TcPO2 measurements in 22atients after revascularization but did not state when in theostoperative period the measurements were obtained. One studyonducted in the immediate (24-hour) postoperative period byamson et al.27 reported that supine foot TcPO2 was significantlyigher postoperatively after successful revascularization whenompared with the preoperative TcPO2 values in 40 patients.umeric values were not provided. Those patients with occludedrafts failed to show any increase in the postoperative TcPO2

esults. Ohgi et al.28 described similar results in a study con-ucted in 24 patients 1 week after leg revascularization. Aetrospective review of 100 revascularization procedures by Ohnd Provan29 found that the surgery was a failure if the preop-rative TcPO2 measurement did not increase by a minimum of5 mm Hg while in the standing position postoperatively. Thisostoperative time interval was not specified.

There is limited nursing research on TcPO2 measurementsnd the effects of nursing activities on patients with vascularisease. A pilot study conducted by Rich30 on four patients 24ours after a lower-extremity arterial revascularization used foureg/body positions when measuring TcPO2: supine, 20-degreeeg elevation, sitting with legs dependent, and reverse Trendelen-urg position. There was no reported difference among TcPO2

esults in any of the four positions on these subjects. Wipke-evis et al.31 found the TcPO2 measurements in 20 patients withenous ulcers to be minimally affected with leg position changeshile breathing room air. However, when supplemental oxygenas added, the TcPO2 was lower in the sitting, leg elevation, and

tanding positions when compared with the supine. Baldwin 32

tudied TcPO2, TcPCO2, and skin temperatures to determineifferences in sacral skin perfusion between two groups ofatients: those who could move in bed and those who werenable to move. It was noted that the sacral TcPO2 was higher inhe subjects who could move about in the bed. Kelechi and

ichel33 reported a decrease in supine leg TcPO2 measurementsn 32 patients with chronic venous disease when compared withealthy subjects.

When a patient is in a sitting position after a lower-extremityrterial revascularization procedure, nurses typically do not al-ow that operative extremity to remain in a dependent positionecause of the potential for edema development. That extremitys usually elevated. However, the use of a 30-degree leg eleva-ion as reported in the TcPO2 medical studies is higher thanustomarily practiced in the clinical setting. Because there are novidence-based nursing guidelines to substantiate the postoper-tive revascularized limb positions recommended, nursing re-earch using TcPO2 as the indicator of dermal oxygenation couldrovide quantitative measurements with the extremity positions.

HEORETICAL FRAMEWORKND CONCEPTUAL MODEL

The physiologic principles of dermal blood flow and theffects of dermal heating guided this study. The theoreticalramework was modified from the conceptual approach devel-

ped by Wipke-Tevis et al.31 Skin microcirculation consists of

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kin oxygen, limb volume, skin temperature, and blood flow.he skin microcirculation is affected by the leg position, numberf red blood cells in the plasma, surgical revascularizationerformed, plasma oxygen, external environment, and TcPO2

lectrode. Figure 1 diagrams the theoretical framework.The conceptual model behind TcPO2 monitoring involves

everal factors. The transcutaneous electrode heats the epidermalurface between 42°C and 45°C, causing an increase in the capillarylood temperature and a local hyperemic effect. The outcome is anncrease in blood flow for a cooling effect. The gradient between therterial and venous capillary limbs is reduced. Autoregulation andhe local vasoconstrictor response are abolished by the increasedemperature.34 Oxygen and carbon dioxide diffuses out of theapillaries into the surrounding tissue. The elevated temperaturelso shifts the oxyhemoglobin dissociation curve to the right,urther increasing the unloading of oxygen into the surroundingetabolically active tissue. The lipid structures within the epi-

ermal surface alter their molecular state when heated from aniform to a more random pattern, typically referred to asliquification,” that improves gaseous diffusion through thekin.35 These factors contribute to the increase in epidermalapillary PO2 similar to arterial PO2 and results in the TcPO2

easurement obtained.36,37

ESIGN

A repeated-measures, experimental design was used to de-ermine which lower-extremity position resulted in the highestcPO2 measurement. The subjects acted as their own controls.he baseline TcPO2 measurement was the supine position.hrough the use of a random numbers table, the subjects weressigned to one of two measurement-starting positions. Theemaining leg position, sitting upright with the legs extended orlevation of the foot of the bed 20 degrees, was alternativelyssigned. The operative extremity limb measurements were se-uentially performed. The principal investigator (PI) collected

igure 1. Theoretical framework.

ll the measurements. �

ETTING

The study was conducted at a community hospital with twoocations: one in an inner city and one in a suburban town located5 miles apart. Between the two facilities, approximately 80 to 90ower-extremity bypass revascularization surgeries were performednnually. Two surgeons from the same cardiovascular physicianroup performed the majority of the surgeries. The surgeons did noterform the surgeries together; a single primary surgeon without aecondary surgeon performed each revascularization. Both surgeonssed similar revascularization techniques.

AMPLE

A convenience sample of 10 subjects with PAD who under-ent a lower-extremity arterial revascularization surgery wassed. Subjects were recruited by word of mouth and flyers.nclusion criteria for all subjects were as follows: aged 21 yearsr more, speak and understand English, no injury, absence of orimitations in movement that would preclude the raising orowering of the legs to measure the oxygen level or position ofhe lower extremities, and a pulse oximetry (SpO2) measurementn room air of 95% or greater.

Exclusion criteria included history of lung disease or aematocrit less than 20% or greater than 47%, current use ofeta-blocker medications, presence of lupus or other autoim-une disorders, pregnancies, or a history of coronary artery

ypass surgery using bilateral internal mammary arteries be-ause this influenced the central chest TcPO2 value. An unsuc-essful lower-extremity revascularization surgery as evidencedy continued ischemia (cold, mottled extremity, absence oforsalis pedis and posterior tibial pulses) or a surgery withomplications (hypotension requiring vasopressors, arrhythmiasequiring resuscitation) also eliminated the subject. Informedonsent was obtained. Approval was obtained through the uni-ersity and hospital investigational review board committees.

NSTRUMENTATION

Three Radiometer TCM30 (Radiometer) TcPO2 monitorsere used to simultaneously measure the TcPO2 values of the

eft chest, 10 cm above the medial malleolus, and the dorsum ofhe foot. The device has two PO2 scale ranges, 0 to 200 mm Hgr 0 to 2000 mm Hg, that may be selected and a drift inalibration value of 1 mm Hg/h.38 The 0 to 200 mm Hg scale wassed for this study. TcPO2 accuracy is better than �2 mm Hg at0.1% of readings at 25°C. The probe contains a modified Clark

olargraphic oxygen sensor and anode (Radiometer; Copenha-en). Temperature accuracy is �0.1°C by the Radiometer mon-tor. The devices were recalibrated according to manufactureruidelines before use on each subject. Previously reported inter-ater reliability testing by the author revealed r � 0.99.30

ntersensor and intrasensor reliability results were r � 0.98o 1.0.

The PhysitempTH-5 Thermalert Monitoring ThermometerPhysitemp; Clifton, NJ) recorded the unheated surface skinemperature on the left chest and dorsum of the foot. The clinicalrobe used with the thermometer was the Physitemp SST-1 skinurface type T thermocouple probe. Instrument accuracy is 0.1°C

1 digit. The skin temperature was maintained between 30°C

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nd 34°C by blanket application to avoid the vasoconstrictiveffects of shivering. Previously reported interprobe and intra-robe reliability testing revealed r � 1.0.30 The Technika high-ccuracy dial hygrometer/thermometer device (Technika; Phoe-ix, AZ) measured room temperature and humidity. Theemperature range is between �15°C and 50°C. The humidityange is 0% to 100% with an accuracy of �5%. Room temper-ture was measured at the bed level. The Model 7491 Digitalarometer by Scientific Sales, Inc. (Lawrenceville, NJ), measuredarometric pressure. The range is 26.5 to 31.5 inches of mercuryith an accuracy of �0.03 inches.

Limb volume was calculated after obtaining limb circumfer-nce measurements using a Gulick weighted tape measure (Cre-tive Health Products; Plymouth, MI) with the leg resting on theobst measuring board (Jobst Medical Devices; Charlotte, SC).he Gulick tape measure is used in girth measurements and has4-ounce spring-loaded device on the end that reduces the

otential for measurement error from variances in the amount ofension applied to the tape. The Jobst measuring board maintainshe leg in a uniform tension. This reduces measurement errorrom variances in calf contraction. Circumferential limb mea-urements are the simplest and most frequently used for estimat-ng limb volume.39,40 Interrater reliability measurements per-ormed by the PI and a lymphedema specialist were high (r �.99). Intrarater limb volume measurements, obtained at threeeparate intervals from a single healthy volunteer, revealed an r

0.98.The SpO2 and heart rate were measured by the Mallinckrodt

ellcor NPB-40 (Mallinckrodt-Nellcor; Pleasanton, CA) hand-eld pulse oximeter. Instrument accuracy for SpO2 in adults withrange of 70% to 100% is � 2 digits. The heart rate range is 20

o 250 bpm with an accuracy of �3 bpm. Before a previous pilottudy conducted by the PI, the SpO2 results from the oximeterere compared with the hospital-owned pulse oximeters with noiscrepancy in values noted.

The arm blood pressures were taken by a conventionalphygmomanometer (Omron Marshall standard series aneroidlood pressure cuff; Los Angeles, CA) and stethoscope (Littmanaster Cardiology 3M Corporation; St. Paul, MN). Ankle-

rachial indices (ABIs) were performed following the techniqueecommended by the Society for Vascular Nursing.41 The sub-ects’ weight and height were obtained using a conventionalospital scale.

The Numeric Rating Scale (NRS) was used to determine theain intensity after each position change. The NRS is a 10-pointcale that the patient uses to score the severity of pain from ainimum score of 0 (no pain) to 10 (worst possible pain).42

Room temperature and humidity were controlled. Gender,ge, and ethnicity were self-reported. Comorbidities, medicationse, and medical history were obtained from the medical record.

REPROCEDURE SUBJECT PREPARATION

The majority of the preparation followed the preparation in arevious pilot study by the author.30 The subjects were asked noto eat or use tobacco for 2 hours before the study and not tongest caffeine for 12 hours before the study.

The PI performed clinical assessments of both legs (skin

olor, temperature, capillary refill, and pulses to indirectly assess w

lood flow). An assessment of the legs for the presence ofoncomitant venous disease was made. The limb circumferenceas obtained following the standard technique used by lymph-

dema specialists. The limb circumference measurements werentered into a software program using a formula that assumeshat limb segments are approximately truncated cones.43 Fromhis program, the limb volume was calculated. The oral temper-ture and time of last pain medication were obtained. Allubjects rested in bed for 30 minutes to allow for acclimation.

The three Radiometer TcPO2 monitors and electrodes weressigned to one of three electrode skin sites through the use of aandom numbers table. These included the left anterior chest ashe central reference, 10 cm above the medial malleolus, and theorsum of the foot over the second cuneiform bone. If scar tissueas present, the electrode was repositioned proximal to the scar.reparation of the skin and TcPO2 electrode application followed

he guidelines as outlined by Clarke44 and were tested in therevious pilot study.30 An adhesive ring electrode was affixed toach of the three prepared areas, and contact solution wasnstilled. The electrode temperature was set at 44°C.

TUDY PROCEDURE

After the electrodes were applied, the subject rested quietlyor an additional 15 minutes in a supine position to allow forlectrode equilibration. After equilibration, the TcPO2 measure-ent was obtained from each site. The skin temperatures were

btained from the foot probe, and the SpO2 was measured. Theoot of the bed was elevated 20 degrees or the subject sat in ahair at the bedside with the legs extended depending on theandom number table result. The legs remained covered through-ut. After a 15-minute electrode stabilization, the TcPO2 valueas recorded from each site. Both chest and foot temperatures

nd SpO2 were obtained. The pain levels were reassessed andecorded using the same scale. The subjects were placed in theemaining position, and the measurements were again obtainedfter the 15-minute electrode equilibration. The study procedureas performed three separate times: preoperatively and 24 and8 hours after surgery.

ATA ANALYSIS

Descriptive and repeated-measures statistics were applied tohe data. Means and standard deviations were calculated on thekin temperatures, TcPO2 measurements, limb volumes, andemaining physiologic data. All data were coded. A statisticianssisted with determining the sample size and calculations. Theata were analyzed using the SPSS statistical software programSPSS Inc, Chicago, IL).

ESULTS

Eleven subjects agreed to participate, with 10 subjects com-leting the protocol. The group consisted of five men and fiveomen with a mean age of 68.0 � 12.7 years (range 43-86ears). The group mean body surface area (m2) was 1.97 � 0.21,nd the body mass index ratio was 29.1 � 8.2. The subjects hadt least two chronic ongoing medical problems and were pre-cribed 4.6 � 2.7 medications daily. There were four subjects

ith diabetes (two with type I diabetes and two with type II

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iabetes). Table I delineates the comorbidities/medical historynd medication use.

Two surgeons from the same practice performed the surgeries.ix procedures were performed on the left leg, and four proceduresere performed on the right leg. Table II summarizes the surgicalrocedures performed by the individual surgeons. There were nontraoperative or postoperative complications. Each subject was outf bed on the first postoperative day (POD). The same postoperativerders were used for all 10 subjects. The mean postoperative lengthf stay was 4.0 � 1.8 days (range 2-8 days).

Preoperatively, 1 of the 10 subjects reported pain with positionhanges. The pain level was classified as 1 of 10 using the NRS. Onoth PODs 1 and 2, pain medication was administered beforeroceeding with the study. This consisted of 7.5 mg of oxycodonend 325 mg acetaminophen in 9 of the 10 subjects and intramus-ular morphine sulfate (10 mg) in one patient. The initial postop-rative NRS assessments were performed before beginning thetudy measurements. On PODs 1 and 2, 8 of the 10 subjectseported no pain (rating � 0) with position change. Two patients

TABLE I

COMORBIDITIES/MEDICAL HISTORY/MEDICATIONS OF SUBJECTS WITHPERIPHERAL ARTERY DISEASE PAD (N � 10)

Comorbidities/medical history

Hypertension � 9Hypercholesterolemia � 7Diabetes � 4Stroke � 3Arthritis � 3Hypothyroidism � 2CHF � 1Peripheral vascular procedures � 9Cardiovascular procedures � 5Orthopedic surgeries � 3Abdominal surgeries � 3Gynecologic surgeries � 3

Current medications Antiplatelet agent � 11ACEI � 7HMG-CoA reductase inhibitor � 7Peripheral vasodilator � 4Diuretic � 3Insulin � 2Oral hypoglycemic � 2Calcium channel blocker � 2Thyroid supplement � 2Neurological � 2Opiates � 2Proton pump inhibitor � 1Digoxin � 1Nitrate � 1Vitamin supplement � 1

CHF, Congestive heart failure; ACEI, angiotensin-converting enzymeinhibitor; HMG-CoA, hydroxymethylglutaryl-coenzyme A.

ated pain at a scale from 1 to 10 with positions. 8

hysiologic variables

There was a significant increase in the revascularized ABIeasurement (P � .001) on POD 1 (0.73 � 0.14) and POD 2

0.82 � 0.13) compared with the preoperative measurement0.54 � 0.10). There was a significant decrease in the postoperativeemoglobin and hematocrit levels compared with the preoperativeeasurements (P � .01 and .007, respectively). On both PODs, thepO2 was decreased in all positions compared with the preoperativendings. Table III summarizes these results.

xtremity skin temperature

There were higher foot skin temperatures in all three extrem-ty positions postoperatively compared with preoperatively. Sit-ing foot skin temperatures were significantly higher on POD 132.9°C � 2.2°C) and POD 2 (32.4°C � 2.0°C) compared withreoperatively (30.1°C � 1.3°C) (P � .008). There was aonsignificant trend toward higher leg-elevated foot skin tem-eratures on PODs 1 and 2 compared with the preoperativeeg-elevated temperature (P � .07). The leg-elevated foot skinemperature was 32.9°C � 2.5°C on POD 1 and 32.5°C � 1.8°Cn POD 2 compared with the preoperative temperature of 31.1°C �.7°C. The supine foot skin temperatures were increased on POD 132.6°C � 2.6°C) and POD 2 (32.3°C � 2.1°C) compared withreoperatively (30.6°C � 1.9°C). However, these results were notignificant (P � .30). This is depicted in Figure 2.

xtremity TcPO2 measurements

The malleolar TcPO2 while in the supine position was highern POD 1 (48.1 � 2.9 mm Hg) and POD 2 (47.7 � 4.2 mm Hg)ompared with the preoperative measurement of 42.3 � 6.9 mmg. The leg-elevated malleolar TcPO2 was also higher on POD(42.0 � 3.4) and POD 2 (43.5 � 6), compared with the

reoperative measurement (39.6 � 6.6 mm Hg). In the sittingosition, the malleolar TcPO2 was lower on POD 1 (48.3 � 9.9m Hg) compared with the preoperative measurement (50.6 �

.9 mm Hg) and higher than baseline on POD 2 (51.8 � 4.6 mmg). None of the malleolar TcPO2 changes were significant (P �

36-.67). Figure 3 details these findings.The postoperative foot TcPO2 while in the supine position

as higher on POD 1 (40.2 � 6.5 mm Hg) compared with thereoperative measurement (39.1 � 6.6 mm Hg) and lower thanaseline on POD 2 (38.9 � 5.3 mm Hg). The foot TcPO2

easurements while in the sitting position were lower on POD 145.6 � 4.9 mm Hg). Although there was an increase on POD 249.0 � 4.2 mm Hg), both postoperative sitting foot TcPO2

alues were lower compared with preoperatively (53.6 � 5.3m Hg). The foot TcPO2 in the leg-elevated position was also

ower on both POD 1 (31.6 � 7.3 mm Hg) and POD 2 (34.6 �.9 mm Hg) compared with preoperatively (38.3 � 7.4 mm Hg).one of the foot TcPO2 findings were significant (P � .49-.92).igure 4 summarizes the results.

imb volumes

The mean lower-extremity limb volume increased on bothODs 1 and 2 compared with the preoperative measurement of

288.0 � 2113.1 cm3. The limb volume on POD 1 was 8456.1 �

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083.7 cm3. On POD 2, the mean limb volume had increased to690.2 � 2289.0 cm3. However, the volume increase was notignificant (P � .12).

DDITIONAL FINDINGS

hest TcPO2

Additional findings were noted that the chest TcPO2 mea-urements in several leg/body positions decreased over time. Thehest TcPO2 in the supine position was lower on POD 1 (52.3 �.1 mm Hg) and POD 2 (51.3 � 9.2 mm Hg) compared with thereoperative measurement (60.9 � 12.5 mm Hg), but the find-ngs were not significant (P � .13). The chest TcPO2 in theeg-elevated position was lower on POD 1 (53.3 � 6.9 mm Hg)

TABLE II

SURGICAL PROCEDURE(S) PERFORMED (N � 1

Surgeon A (n � 8)

L femoral-popliteal bypass synthetic graft (2)

L femoral-popliteal bypass synthetic graft and Miller cuff s

L femoral-popliteal bypass synthetic graft and Miller cuff sligation/excision of varicose vein (1)

L femoral-popliteal bypass composite graft and femoral-poendarterectomy (1)

R femoral-tibial bypass SVG with femoral and iliac endart

R femoral-popliteal bypass synthetic graft (1)

R, Right; L, left; SVG, saphenous vein graft.

TABLE III

PHYSIOLOGIC VARIABLES OVER TIME FOR SU(N � 10)

Mean physiologic variables � SD Preoperative

Systolic BP (mm Hg) 133.1 � 14.8

Diastolic BP (mm Hg) 70.2 � 7.5

Revascularized ABI (ratio) 0.54 � 0.10

Oral temperature (Celsius) N/A

Supine SpO2 (%) 96 � 1.9

Sitting SpO2 (%) 96 � 1.3

Leg-elevated SpO2 (%) 97 � 1.6

Hemoglobin (g/dL) 12.9 � 1.5

Hematocrit (%) 38.6 � 5.2

N/A, Not available; POD, postoperative day; BP, blood pressure; SpO2, p

*Significant.

nd POD 2 (54.5 � 5.6 mm Hg) compared with the preoperative p

hest TcPO2 (63.8 � 9.6 mm Hg) in the leg-elevated position,nd the difference was significant (P � .03). When individuallyomparing the preoperative chest TcPO2 while in the leg-levated position with the POD 1 measurement, the POD 1 chestcPO2 in the leg-elevated position was lower than preoperatively

P � .01). The same finding was noted between the POD 2 chestcPO2 while in the leg-elevated position and the chest TcPO2

hile in the leg-elevated position preoperatively (P � .03).here was no significant difference between the chest TcPO2

easurements while in the leg-elevated position on PODs 1 and(P � .26). There was a nonsignificant trend that the chest

cPO2 of the subjects with PAD while in the sitting position wasower on POD 1 (54.7 � 5.7 mm Hg) and POD 2 (55.3 � 5.4

m Hg) when compared with chest TcPO2 while in the sitting

Surgeon B (n � 2)

R femoral-popliteal bypass SVG (1)

nous vein (2) R femoral-popliteal bypass syntheticgraft (1)

nous vein with

al

omy (1)

CTS WITH PERIPHERAL ARTERY DISEASE

POD 1 POD 2 Significance

125.6 � 17.2 128.0 � 22.7 NS

66.0 � 6.7 63.6 � 7.7 NS

0.73 � .14 0.82 � 0.13 .001*

36.6 � 0.40 36.8 � 0.43 NS

94 � 2.0 94 � 4.1 NS

95 � 2.3 95 � 2.4 .02*

94 � 1.8 95 � 2.7 .007*

11.0 � 1.2 N/A .01*

32.2 � 3.5 N/A .007*

ximetry; NS, not significant.

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PAGE 12 MARCH 2008JOURNAL OF VASCULAR NURSINGwww.jvascnurs.net

ISCUSSION

Hypothesis 1: Skin temperature on the lower extremity wille lower preoperatively in the subjects with PAD compared with4 and 48 hours postoperatively. This was partially confirmed byhe statistically significant increase in the sitting foot skin tem-eratures on PODs 1 and 2. This was most likely a normalostoperative inflammatory-immune response from tissue injuryaused by the surgical trauma. In addition, a small sample size orype II error may have been factors influencing these findings.

Hypothesis 2: The skin oxygen on the lower extremity will be

**

05

101520253035

Preop POD #1 POD #2

Time

Skin Temperature

oCSupineSupine SDLeg ElevatedLeg Elevated SDSittingSitting SD

igure 2. PAD extremity skin temperatures over time. **Sitting footemperatures on PODs 1 and 2 greater than preoperative temper-tures (P � .008). SD, standard deviation; POD, postoperative day.

igure 3. Malleolar TcPO2 measurements over time. No significantifferences in malleolar TcPO2 over time. SE, standard error;cPO2, transcutaneous oxygen; POD, postoperative day.

igure 4. Foot TcPO2 measurements over time. No significantifferences in foot TcPO2 over time. SE, standard error; TcPO2,ranscutaneous oxygen; POD, postoperative day.

ower preoperatively in the subjects with PAD compared with 24 m

nd 48 hours postoperatively. This hypothesis was not supportedy the results. There were several possible explanations for theack of change in the malleolar and foot TcPO2 measurements.lthough there was a significant increase in the postoperativeBI measurements, the skin microcirculation response may be

lower to respond to the revascularization procedure. This delayay be from an alteration in capillary permeability caused by the

ostoperative inflammation. Although there was an increase inxtremity blood flow at the macrocirculation level within thearge vessels, as evidenced by the increase in the postoperativeBI, the microcirculation level may have been more affected by

he chemical mediators produced by the stress response. Anotherotential factor may be the increase in postoperative limb vol-me. Although the increase was not statistically significant, itay have been a clinically important contributor to the lack of

he postoperative malleolar and foot TcPO2 changes. A thirdeason for the unchanged lower-extremity TcPO2 values afterurgery may have been the significant decrease in the postoper-tive SpO2 measurements. The SpO2 indirectly assesses thelasma arterial oxygen level. If the arterial oxygen has de-reased, there is a reduced amount of oxygen available to theissues. The decrease in the postoperative hemoglobin and he-atocrit levels may have affected the postoperative TcPO2. In

ddition, a small sample size resulting in a Type II error mayave been a contributing factor.

Hypothesis 3: Preoperative lower-extremity limb volume inhe subjects with PAD will not be different compared with theower-extremity limb volume 24 and 48 hours postoperatively.his hypothesis was supported by the nonsignificant increase in

he postoperative revascularized extremity limb volume. Theack of volume difference may be attributable to several causes.here were two leg incisions made by the surgeons to perform

he revascularization surgery: an approximately 10 to 20-cmncision downward from the femoral crease and a 10-cm incisionxtending downward from the medial aspect of the patella. Theres a relationship between the size of the surgical incision andubsequent inflammatory-immune response. In addition, the sub-ects with PAD had the foot of the bed elevated 20 degrees as atandard practice. A second postoperative order was that whilehe patient was sitting, the legs were to be level, not dependent.he combination of the smaller incisions and leg elevation mayave reduced capillary fluid translocation from the postoperativenflammatory-immune response and subsequently lessened re-ional fluid collection. Last, a small sample size may haveaused a Type II error.

The significant increase in the ABI on PODs 1 and 2ompared with the preoperative measurement was due to theevascularization surgery performed. The improvement oflood flow to the foot resulted in an increase in the ankleystolic blood pressure.

The significant decrease in SpO2 observed on both PODs 1nd 2 may have been the result of atelectasis. This decreases theurface area for oxygenation. Atelectasis is the most commonulmonary complication in the postoperative period.45

The decrease in the chest TcPO2 measurements in all threeeg/body positions 24 and 48 hours after surgery was aecondary study outcome. The lower chest TcPO2 measure-

ents may have been due to atelectasis changes. An addi-

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Vol. XXVI No. 1 PAGE 13JOURNAL OF VASCULAR NURSINGwww.jvascnurs.net

ional reason for the chest TcPO2 decrease may be a decreasen PAD subject mobility.

IMITATIONS

The limitations of this research included the use of a conve-ience sample with a small sample size. Because this was anxperimental study involving two surgeons with specific inclu-ion and exclusion criteria, generalization is not possible. Notategorizing the subjects with PAD on the basis of Fontainelassification resulted in a nonstratified group with differingevels of ischemia. Not documenting the vascular clamp timerohibited the ability to assess the influence of this variable onkin temperature in reactive hyperemia. Not assessing for theresence of neuropathy and orthostatic changes in the diabeticatients did not allow for an accurate assessment of their influ-nce on the group measurements. Including the diabetic ABIesults with the other findings may have increased the mean ABIeported.

Not measuring the limb volume of both lower extremitiesas a study limitation because it has been reported that theominant side has a larger volume than the nondominant side.ot calculating the limb volumes bilaterally negated the ability

o assess for differences and compare. Several of the medicationsaken by the subjects (angiotensin-converting enzyme inhibitors,alcium channel blockers, vasodilators, and antiplatelet agents)ay have positively influenced (by increasing) the TcPO2 mea-

urements through the effect on the skin microcirculation.

URSING IMPLICATIONS

Both leg-elevated and sitting with legs-extended positionsre frequently used by nursing to reduce the development ofostoperative edema. The use of the positions included in thisesearch may optimize patient outcomes by lessening the extentf postoperative edema. Extending this practice into dischargeatient education would be appropriate to continue with edemaeduction.

Monitoring SpO2 levels on a regular basis, as an additionalital sign in the postoperative patient, is an area of nursingssessment. The effects of the lower postoperative arterial oxy-en level were evident in the decreased SpO2 and chest TcPO2

easurements reported on the subjects with PAD in this study.n addition, the patients with PAD had a decrease in postoper-tive hemoglobin and hematocrit levels. Because of these twoactors, extending the use of supplemental oxygen to PODs 1 andmay improve oxygen delivery and promote wound healing in

hese subjects. The standard interventions of incentive spirome-ry, coughing and deep breathing exercises, and early mobiliza-ion are other important nursing interventions that may reducetelectasis development.

Postoperative control of pain and hydration remain importantarameters for tissue perfusion and postoperative nursing care.he reported vasoconstrictive effects of postoperative pain on

he sympathetic nervous system support the administration ofpiates for pain control. Assessment and monitoring of patients’ydration status assist in optimizing tissue oxygenation anderfusion. Although not included as a data point for this study,

ostoperative glycemic monitoring and control in the patients

ith PAD and diabetes have been shown to improve woundealing and tissue perfusion.

The elevation in postoperative foot skin temperature is ahysiologic prompter for the nurse to monitor the extent ofnflammation, edema, and neurovascular status of the extremitylong with the peripheral pulses.

In patients who have undergone peripheral artery surgery, theosition of the revascularized extremity is a means by whichursing may maximize extremity blood flow and the underlyingissue oxygenation. This study used TcPO2 measurements as theuantifier to identify the best postoperative extremity position. Itas found that the supine, 20-degree leg elevation or sittingpright with legs extended positions did not significantly affecthe postoperative TcPO2 measurements within this group ofubjects with PAD. Further research is indicated.

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