Computerized segmental plethysmography and laser flowmetry

Computerized Segmental Plethysmography Laser Flowmetry

and

Travis Winsor, MD, Alfred E. Sibley, and Amani Mikail, MD

A new compute&ed plethysmograph allows segments of the vascular system to be examined accurately and automatically. Laser flowmetry allows blood ftow measurements to be made of digital circulation for vascular abnormalities. With the 2 new instnanents, large and small vessel circulations can he measured quickly and easily. Disease of these vessels can be readily detected. Thus, appropriate medical or surgical therapy can be investigated. (Am J Cardiol1989;64:57G6OC)

From the University of Southern California School of Medicine, Los Angeles, California. Address for reprints: Travis Winsor, MD, 4041 Wilshire Boulevard, Los Angeles, California 90010.

F

ive great erascan be recognizedin the development of our knowledge of the peripheral circulation. Theseare the erasof: (1) observationof the living; (2) dissectionof the dead; (3) physiologic investigation; (4) application of optics, mathematics and physics; and (5) application of electronics. The first era beganwith Hippocrates, 460 to 377 BC, who recognizedand describedgangreneand the effectsof other peripheral vascular diseases.The secondera began at the time of Leonardo Da Vinci, 1452 to 1515, who noticed that the arteries of the young were elastic and straight and those of the old were thick, rigid and tortuous.The third era beganwith William Harvey in 1578to 1657, who establishedthe scientific method for physiologic investigation and showedthat blood circulated in a closed systemof vessels.The fourth era occurred at the time of Antony van Leeuwenhoek(1632 to 1723) and J. L. Poiseuille (1799 to 1869) with the development of optics, mathematicsand physics.Van Leeuwenhoekwas the first to usethe microscopefor the systematicstudy of the blood vessels.Poiseuilleusedmathematicsto describe the factors that control the flow of blood in vessels. The fifth era is that of electronics which began with the development of the vacuum tube and a variety of electronic devicesby De Forest.Thesedevelopmentshave made possible numerous instruments for the objective measurementsof the peripheral circulation.’ This report showsthe results obtained from useof the LaserFlo@(TSI Inc., Minneapolis, Minnesota) and computerized Sonicaid/Winsor (Oxford Sonicaid, Chichester, England) plethysmograph.Studies must start with a knowledgeof the functional anatomy of the human circulation and nervous system and an understanding of the way in which the various organsof the body affect blood flow. Important aspectsof the physical examination of the vascular systemare consideredin the light of various objective studies with emphasisplaced on instrumental examination. This is a practical and informative laboratory examination that makesobjective observationsof the peripheral circulation possible.The information gained from thesestudiesis important in understanding disease, determining treatment and making comparisonsof various pharmacologicagents,physical, therapeutic and surgical procedures.2 The quantitative measurements from person to person (computerizedSonicaid) can be comparedto a standard of 100:lessthan 100indicates diseaseand more than 100 indicates normality. This method provides an easy,standard technique for analysis of individual casesand for data bank storageof information from wide geographic sources.

THE AMERICAN JOURNAL OF CARDIOLOGY AUGUST 2. 1989

57C

A SYMPOSIUM: THE GEORGE E. BURCH FESTSCHRIFT

40

0 10"

30"

25"

40"

45"

Temperature (72) FIGURE 1. Rdation of toe ilow to cWerent toe temperatures inhoal8lyrubjectsandpa8entswHhdi~rre.nw!bostpolnt ofseparationbtweengroupI(nomd)dgroupII(abnormd)is18.&lbebestwparathoccudwhentheprobe temperaturewar40”to4s”.Theprobetemper~wasobtainedfmnl~plantarsulfacoof8leb%too(mlot8owper 100 ml/min); room temperature was 23”. LDF = laser Doppler 8ow.

INSTRUMENTS USED The instruments used in this study were: (1) Burch pneumoplethysmograph,which photographedthe motion of a filament as it was deflected by the pulsation of the transducer. The movementwas recorded optically.3 The instrument was clumsy and difficult to use but results were reasonablyprecise.The venousocclusiontechnique was used to measure blood flo~.~ (2) the standardized electronic plethysmograph, which had many automated features; (3) the electronic instrument, a standard plethysmograph that wascomputerizedto a certain extent in

that the mathematic comparisonof the wave forms was determined; (4) a completely computerized plethysmograph from which recordingswere madeand results were printed out by the computer,usedon the legs,fingers and toes; and (5) The LaserFlo which showed differences between health and diseasein subjects. The LaserFlo is an electric photodetectingmeter that gives information from a ratio of the alternating and direct-current photodetectorvoltages.A frequency of the moving red cells is determined. Blood flow is the product of the blood volume and blood velocity. More than 50 normal subjectsand more than 50 ambulatory patients with arteriosclerosisobliterans were studied and the results recorded and compared with the previous studies. The LaserFlo hasbeenusedespeciallyto differentiate betweenhealth and diseasein 2 groups of subjectsunder various circumstances.5 Group I consistedof patients without peripheral vascular diseaseand showeda marked increasein blood flow as the toe temperature increased(Fig. 1 and 2). In reactive hyperemia, there was an abrupt increase in blood flow, occurring immediately after releaseof the tourniquet. Local heat to the toe, without increasing room temperature, increasedcirculation. When both room and skin temperatureswere raised,with a blanket applied, a large increasein circulation wasproduced.Thus, it can be seen that the laser devicecould be usedrapidly and effectively and help differentiate between health and disease. Group II consistedof patients with peripheral vascular disease.The laser blood flow values were abnormally low when the patients were supine (Fig. 1). When the toe temperature was 23’, the values were lower in patients with than without disease.With a Sminute reactive hyperemia, there is about a 3-seconddelay before reactive

2.0.. ::

0 0

- 1.5 -. . .-I= E .

FlGURE 2. Relation ol toe Sow to skin temperatureslnnmnalpersas.lb8log of blood flow in normal subjects (ml/mid 1OOcc) plotted against hear skh temperatmfi moastammts. W-WblClWSdtlWblOOdllOWOf -gnatly thetoos.

z * 1.0 -. 0 ii Lt. 0 0” 0.5-q A

0 SKIN

58c

TEMPERATURE

(-C )

THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 64

hyperemiabegins,after which the flow failed to reachfull reactive hyperemic values in patients with disease.Local heating of the big toe to 40” had very little effect on increasing the abnormal circulation. Body heating combined with heat applied locally had a similar minimal or absenteffect. By elevating the room temperature to 40”, there was still very little effect. The greatest effect was seenin group I in which the room temperaturewas at 40’ and an electric blanket was applied to the abdomen. Group II had a minimal increasein skin flow as the room temperature increased. When both the room and skin temperatureswere increased,the largest increasein circulation was seen.Thus, it can be seenthat the LaserFlo device is a rapid and useful tool for differentiating between health and disease. The Sonicaid/Winsor wasusedprimarily for measuring the state of the blood vesselsby meansof the arterial pulses.Pulse recording cuffs were placed at the brachia, wrists, groins, above and below the knees and at the ankles. Various calculations were obtained to indicate whether the artery between these cuffs was normal.3 To make this determination, it was necessaryto find a line of decision or a point of confidencein order to separate groups of normal and abnormal subjects (Table I). Pulse amplitudes were automatically calibrated and all data ratified. The pulseamplitudes correctedto 1 ml were determined. The arterial segmentswere easily computed automatically. From thesedeterminations, the ratios between 2 arteries were determined. The artery cuff segments and their predicted ratios were, e.g., pulse amplitude abovekneedivided by pulseamplitude divided at the groin, giving a ratio that reflects the state of the artery betweenthe 2 pulses(Fig. 3): I = Iliac, 1.OO;II = superfemoral, 0.50; III = popliteal, 0.50; IV = peroneal,0.45; V = all of these 0.40 ankle/wrist 0.90. Numbers above 100 tend to fall within normal groups. Numbers below 100 fall in the abnormal group. With use of these various instruments on the human extremity, we have repeatedly observed a certain phenomenonknown as the diversion phenomenondescribed earlier by Winsor and Hyman.2 A few clinical examples follow: Patient I: Shunting of blood flow through the skin from the proximal to the more distal portions of the limb was seenin a 65-year-old man who had arteriosclerosis obliterans of the legs. Before sympathectomy was performed, the skin of the foot and toes was somewhat atrophic and the toeswere cool. After surgery, there was an immediate increasein the temperature of the skin of the toesreflecting releaseof the sympathetic tone in skin of the distal part of the foot. However, by the third postoperative day, a gangrenousarea appearedover the dorsal and more proximal portion of the foot in the region of the dorsalis pedis artery. The diversion here may have beencausedby greater dilatation of the distal than of the proximal vesselsof the skin of the foot, becausesympathetic vasomotortone is greater in the former than in the latter. Similar caseshave beendescribedby Freeman N et al (personal communication).

TABLE

I Example of a 12-Lead Segmental Plethysmogram with Calculations Made Automatically by Computer Right

Segments Corrected

Left

Pulse Amplitude

Brachium Wrist Groin Above knee Below knee Ankle

0.82

0.60

0.92 0.84 0.62 0.36

0.80 0.69 0.62 0.41

Measured Arterial Segment Ratios Iliac (GR/ER) Superficial femoral (AK/GR) Popliteal (BK/AK) Calf (AN/BK) Ankle/brachium Ankle/wrist

1.12 0.91 0.74 0.58 0.44

Predicted

Reference Levels

lilac Superficial femoral Popliteal Calf Ankle/brachium Ankle/wrist

1.33 0.86 0.90 0.66 0.68

1.0 0.50 0.50 0.45 0.4-C 0.90

Segmental index (Measured/Predicted Iliac Superficial femoral Popliteal Calf Ankle/brachium Ankle/wrist

%)*

112 183 148 129 110

*Greater than 100%. normal: less than loO%, abnormal. AK = above knee; AN = ankle: BK = below knee; BR = brachium;

FIGURE 3. Computerized ocemsntal pkthymograph in Table 1. The number in the upper right

scribed

oteacbboxbasboencome&d

133 173 180 147 171

GR = gran.

dohand

corner

forti~OfCUtt,VOblmOOf

airinthecuffandcardiacrate.Thecondith ofthearterybehneenany2cuttrisexpnuedbyaratiooMainedbydividing thelowercuffbythsuppwadfandthisvaheiscompared withapredictedratioas~wninTabkI.Theprerwreof maximalpulsationisthf+presmre atwbicbibotanostpulso wave was found.

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AUGUST 2. 1989

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A SYMPOSIUM: THE GEORGE E. BURCH FESTSCHRIFT Patient II: Diversion of blood flow to normal vascular beds from an obstructed vascular bed was seenin a 37year-old man who had thrombosis of the left axillary artery as a result of a gunshot wound. Heat applied to the body resulted in an increasein pulsation and blood flow through the right index finger with a simultaneous increasein these measurementsin the left index finger. Patient III: This 35year-old white man with typical thromboangiitis obliterans of the vesselsof the right foot but with a normal left leg underwent plethysmography. Isoxsuprine (Meade-Johnson) was given intravenously, after which blood flow decreasedin the abnormal side and increased in the normal side. Both of these results were consistent with statementsof Mendlowitz and others, that generalized vasodilating drugs may decrease circulation in a leg or arm with obstructive arterial disease.When a drug hasa differential effect on the vascular muscle and skin, an increase in blood flow in one area may be accompaniedby a simultaneous decreasein the other. Patient IV: Blood flow through the forearm and tingertip was simultaneously measuredbefore and 15 minutes after intravenous administration of 5 mg of Arlidin@ (Norsuprifen). The influence in forearm blood flow essentially increased muscle blood flow and greatly decreasedfingertip flow. Patient V: Another example of the diversion of the blood away from the skin of the foot to the muscle was observedin a 65-year-old man with arteriosclerosisoblit-

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THE AMERICAN JOURNAL OF CARDIOLOGY VOLUME 64

erans in whom isoxsuprine was used. As a result, . flow in the calf muscleincreasedfrom 5 to 13ml/ 100ml leg/min, but in the toe it decreasedfrom 7 to 1 to 4 ml/ of toe. DISCUSSION

New electronic devicesmake it possible to measur volume (rate of flow) semiquantitatively on various sut faces (flat, curved or tubular structures) of the body under a variety of different conditions. Simultaneous measurementscan be obtained in skin and muscleand the unit of expressionis the same: 100 ml of blood flow per 100 ml of tissue per minute. Acknowledgment: We thank Sally Cody, Elizabeth Paynter and Amani M&ail, MD, for their assistancein developing these studies.

REFERENCES

1. Winsor T. Peripheral Vascular DiseasesSpringfield, IL Charles C. Thomas, 1959:IX-X. 2. Winsor T, Hyman C. A Primer of Peripheral Vascular Diseases.Philadelphia, PA: Leo & Febiger, 1965: 5-6. 3. Ray T, Burch GE, DeBakey ME. The “borrowing-lending” hemodynamic phenomenon(hemometakinesia)and its therapeutic application in peripheral vascular disturbances.New Orleans Med & Surg J 1947;1006-1012. 4. Winsor T, Haumschild DJ, Winsor D, Mikail A. Influence of local and environmental temperatureson cutaneouscirculation with use of laser doppler flowmetry. Angi~logy 1989;40:421-428. 3. Winsor T. Clinical plethysmography. Part I. An improved direct writing plethysmograph.Part II. Plethysmographicproceduresof clinical importance. Angiolqy

1953;4:134-164.