[Angiological exploration of a new clinical significance: peripheral & visceral photoplethysmography & rheography. I. Peripheral & visceral photoplethysmography].
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Humans↗
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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)
Adult↗
Photoplethysmography: a valuable noninvasive tool in the assessment of venous dysfunction?
We have investigated the photoplethysmography findings in 152 patients admitted to the Middlesex Hospital Vascular Laboratory with suspected lower limb venous disease, and we compared the results obtained with patient grouping using clinical criteria and the presence of reflux on color duplex scanning. All photoplethysmography traces were normalized with use of computer software to enable direct comparison between the traces. The parameters investigated were the 95% and 50% refilling times and the initial gradient of the refilling curve. Receiver operating characteristic curves were constructed to determine which parameter was the most useful predictor of disease and to identify which value within each observation gave the greatest sensitivity and specificity. We found a large overlap between interquartile values for all three parameters, with limbs grouped both clinically and by duplex scanning, making differentiation between normal and abnormal limbs difficult on the basis of photoplethysmography traces alone. We found that a 95% refilling time of less than 15 seconds indicated venous dysfunction with the greatest sensitivity and specificity and suggest that this value is most useful. Photoplethysmography readings are reproducible, noninvasive, and correlate well with the presence of clinical disease, and photoplethysmography remains useful in the assessment of venous dysfunction.
Adult↗
Photoplethysmography reexamined: lack of correlation with duplex scanning.
In a prospective study a comparison was made between the results of photoplethysmography and ultrasonic duplex scanning in 151 consecutive legs with swelling, aching, and suspected venous insufficiency. Thirty-four percent of the legs had a history of previous deep venous thrombosis, 26% had undergone previous superficial vein surgery, and 11% had active or healed ulceration. Photoplethysmographic findings were normal in 86 (57%) of these legs and indicated deep venous disease in 33 (22%). With duplex scanning, incompetent vein segments were found in 140 legs (93%). The kappa coefficient of agreement between the result, classified as either normal, superficial disease only, or deep incompetence, was 0.12 +/- 0.06. In legs with superficial disease, the number of incompetent levels was no greater in legs with abnormal results of photoplethysmography than in legs with normal results of photoplethysmography. In general, an abnormal photoplethysmographic result is related to multilevel reflux and the presence of visible skin changes. Photoplethysmography had the same value, in these patients, to predict the presence of multilevel reflux as had inspection of the skin of the goiter area. These results do not warrant the continued use of photoplethysmography for surgical decision making in patients with suspected venous insufficiency.
Adult↗
[Significance of photoplethysmography in the diagnosis of deep venous insufficiency].
In chronic venous insufficiency, photoplethysmography, in addition to the clinical and Doppler examinations, offers important informations in the differential diagnosis between deep and superficial venous insufficiency. It is a simple, reproductible, non invasive test with data similar to venous pressure measurements. Photoplethysmography permits to set up quantitative criteria of venous insufficiency. It establishes the role of reflux in the dysfunction of the leg venous pump, and makes it possible to adjust for prescription of additional explorations, in particular popliteal or femoral dynamic phlebography. Furthermore, photoplethysmography offers a solid criterion to differentiate between various therapeutic surgeries: surgery of the superficial network, surgery of collateral veins, surgery to restore the deep venous network. Moreover, photoplethysmography is a useful tool to quantitatively appreciate the results of the venous insufficiency treatment. In conclusion, photoplethysmography appears as an additional examination necessary for functional exploration in chronic venous insufficiency. Its use in practical angiology is going to develop in view of its interesting results and its reasonable cost.
Chronic Disease↗
[Diagnostic value and significance of photoplethysmography in venous insufficiency].
In this study, including 62 patients, or 104 lower extremities, the author demonstrates first, with the chi-2 test, that the method based on Photoplethysmography has a good diagnostic value (sensitivity: 92%, specificity: 88%). Then, with the Student t-test, he demonstrates that the advantage of Photoplethysmography in venous insufficiency is to differentiate easily normal subjects from subjects affected with valve insufficiency, and to establish the differential diagnosis between superficial valvular insufficiency and deep valvular insufficiency. On the contrary, in analyzing the discrepancies between clinical examination and the results of Photoplethysmography, he demonstrates that the diagnosis obtained with Photoplethysmography is limited in the presence of edema, isolated varicose veins, Phlebitis and arterial disease, or during an ineffective compression of the reflux of the superficial venous system. Finally, the author suggests an approach in patients with chronic venous insufficiency, based on clinical examination, Doppler examination and Photoplethysmography.
Aged↗
Vibration syndrome diagnosis using a cooling test verified by computerized photoplethysmography.
This study addresses the problem of vibration syndrome diagnosis by means of a cooling test verified by photoplethysmography. Measurement was taken on a small area on the fingertip plexus in which many arterio-venous anastomoses are present. In the opinion of many authors, flow disorders in this area are more typical for developing vibration syndrome than changes in the micro vessels. The study group comprised 128 subjects (58 women aged 40.9 +/- 5.4 years and 70 men aged 38.7 +/- 8.8 years) exposed to vibration. The control group consisted of 41 people (20 women aged 39.6 +/- 7.3 years and 21 men aged 39.3 +/- 6.4 years) who were not exposed to vibration. The patients were examined by a questionnaire and then a vibration perception threshold test and a cooling test were performed. The cooling test was verified both visually and using the computer method. Measurement data (S1, S2 and A) for each patient were obtained from averaging three pulse graphs. We departed from an average of 60 graphs (and more), the standard established in the literature, because of the cooling test specification, which causes huge thermodynamic parameter changeability in the plexus mass of the small finger under pulse waves coming one after another. A longer measurement time will reflect the thermal drift of the tested area in a direction to compensate for the reduced temperature. In the control group, all subjects showed an increase in planimetric indicators during the cooling test verified by computerized photoplethysmography. In the study group visual verification of the cooling test was positive in eight cases (6.2%) and the vibration perception threshold test was positive in seven cases (5.5%), but in computerized photoplethysmography the planimetric indicators decreased after cooling in 87 (67.4%) cases. Computer photoplethysmography is highly specific and shows greater sensitivity in detecting preclinical forms of vascular-type vibration syndrome when compared with palesthesiometry, the visually verified cooling test and the questionnaire. The proposed test enables the detection of vascular disorders in the prodromal period and gives time for preventive measures to be taken.
Adult↗
[Use of photoplethysmography with calibration in vivo for assessing venous hemodynamics of the lower extremity and particularly ambulatory venous pressure and refilling time after exercise].
Several invasive and non-invasive methods are used actually for the appreciation of the morphology and the function of the venous system of the lower extremity. Hemodynamic parameters like the ambulatory venous pressure and the venous refilling time can not be determined without invasive measurements. This report describes the results of a prospective comparison of the ambulatory venous pressure and the venous refilling time with the in vivo calibrated photoplethysmography and with invasive measurements. Postural changes of hydrostatic pressure permitted in vivo calibration of the photoplethysmograph. We recorded quantitative photoplethysmography (PPG) ambulatory venous pressure and venous refilling time in 20 normal subjects, 20 patients with superficial varicosis and in 20 patients with chronic venous insufficiency. Quantitative photoplethysmography correlated closely with invasive measurements of ambulatory venous pressure with respect to estimated drop in superficial venous pressure and recovery time. PPG estimates of intravenous pressure in normal patients (24 +/- 9 mm Hg), in patients with varicosis (42 +/- 7 mm Hg) and post-thrombosis patients (63 +/- 9 mm Hg) agreed with ambulatory venous pressure measurements 22 +/- 9 mm Hg, 40 +/- 6 mm Hg and 61 +/- 6 mm Hg, respectively. Non invasive, quantitative photoplethysmography may prove to be an accurate estimate of ambulatory venous pressure in patients with superficial varicosis and in patients with chronic venous insufficiency.
Exercise Test↗
Use of photoplethysmography to determine the survival length of skin flaps.
Photoplethysmography was used to evaluate 14 skin flaps in the pig. Eight skin flaps were 4x12 cm and were based dorsally. Six skin flaps were 4x18 cm and were based ventrally. All flaps were designed to undergo necrosis of the distal end. After elevation of the flap, blood flow to the skin flaps was estimated immediately by means of intravenously administered fluorescein. Photoplethysmography was used to determine blood flow to the skin flaps at 3, 24, 72, and 144 hours after elevation. Surviving length of the skin flaps was measured at nine days. Fluorescein accurately predicted the surviving length of the skin flaps. Photoplethysmography did not show a decrease in blood flow at the level of fluorescein penetration 3 or 48 hours after elevation. However, 72 and 144 hours after elevation, an abrupt decrease in blood flow was noted by photoplethysmography at the level of eventual skin necrosis.
Animals↗
Photoplethysmography in the diagnosis of superficial venous valvular incompetence.
Photoplethysmography was compared with clinical investigation combined with Doppler ultrasonography in the diagnosis of superficial venous valvular incompetence of the lower limb. In 268 consecutive patients, 536 limbs were investigated. A total of 22.1 per cent of the photoplethysmographic investigations were uninterpretable because they did not allow reliable determination of the refilling time. Agreement between clinical investigation combined with Doppler ultrasonography and photoplethysmography was found to be poor (kappa = 0.30). These results suggest that photoplethysmography is not the non-invasive method of choice for routine evaluation of superficial venous valvular incompetence of the leg.
Adolescent↗
Photoplethysmography for simultaneous recording of heart and respiratory rates in newborn infants.
Ten newborn infants, born at 25-41 wk of gestation and nursed in a neonatal intensive care unit or in a neonatal intermediate care unit, underwent monitoring of heart and respiratory rates with a new technique using an optical sensor, 0-60 d postnatally. The aim of this study was to compare the heart and respiratory rates recorded in infants by photoplethysmography with a probe positioned on three monitoring sites, namely the leg, buttock and interscapular region, with the rates recorded by ECG and transthoracic impedance, respectively. The recordings were compared in order to determine which individual heart beats and respiratory cycles were recorded with one or both relevant techniques. A high degree of association (r =0.99) was found between the respiratory rates recorded by photoplethysmography and by transthoracic impedance. Recordings of heart rates by ECG were also highly associated with the photoplethysmographic rates as measured at two (r = 0.99) of the three monitoring sites. It is concluded that heart and respiratory rates in infants can be monitored satisfactorily by the new method based on photoplethysmography. This method offers the advantage of recording several physiological parameters non-invasively with a single probe during the neonatal period.
Apnea↗
Transmittance photoplethysmography with near-infrared laser diodes in intra-peritoneal organs.
Photoplethysmography and pulse oximetry are techniques based on optical principles, which are widely used in medical practice for non-invasive monitoring. There are some processes which may affect specific organs or parts without a significant repercussion on the information provided non-invasively. Here, we report on the preliminary results obtained by transmittance photoplethysmography in pig intra-peritoneal organs along a surgical intervention, using a measurement system based on two near-infrared laser diodes. Analysis of the signals recorded at 750 nm and 850 nm in the mesentery root, mesocolon, gastric wall and aorta artery has shown the affordability of performing in situ photoplethysmography for visceral perfusion evaluation.
Animals↗
Use of photoplethysmography to determine gastrointestinal perfusion pressure: an experimental canine model.
OBJECTIVES: To develop an experimental model to assess the parietal perfusion pressure (PPP) of the digestive tract using photoplethysmography. MATERIALS AND METHODS: Twenty-two mongrel dogs were used. Progressive external compression was applied to the intestinal wall and the PPP was assessed with photoplethysmography. The study group was divided into two groups. In group 1 PPP was measured at the levels of the stomach, duodenum, jejunum and transverse colon. In group 2 PPP was measured after temporary occlusion of the truncal and marginal circulation of the jejunum to provide further variables. RESULTS: The PPP decreased significantly for each successive distal section. Correlation coefficients and indices for PPP and mean arterial pressures were statistically significant (p < 0.005). Truncal occlusion provoked a drop in PPP whereas marginal occlusion scarcely modified the basal results. CONCLUSIONS: Photoplethysmography, through measurements of the residual arterial wave amplitude, is a valid method of determining quantitatively the PPP of the digestive tract and could be useful in a clinical environment.
Animals↗
The use of photoplethysmography and Doppler ultrasound to predict anastomotic viability after segmental intestinal ischaemia in dogs.
OBJECTIVE: To compare photoplethysmography and Doppler ultrasonography in the prediction of the viability of experimental jejunoileal anastomoses in the presence of arterial (n = 11), venous (n = 11), and mixed arterial and venous (n = 9) segmental ischaemia. DESIGN: Experimental open study. MATERIAL: 31 Mongrel dogs. INTERVENTIONS: Laparotomy, selective devascularisation, and anastomosis. In 20 of the experiments a bolus injection of papaverine was given into the superior mesenteric artery. Second laparotomy on day 15, or earlier if indicated. OUTCOME MEASURES: Correlation between photoplethysmography, Doppler ultrasonography, and macroscopic and histological findings. RESULTS: All non-viable anastomoses had photoplethysmographic wave amplitudes of less than 10% of the control value, with sensitivity and specificity of 100%. Venous volume and maximum venous outflow had a sensitivity of 72% and a specificity of 77%. Doppler ultrasonography had a sensitivity of 100%, but a specificity of only 67%. Papaverine had no effect on photoplethysmographic wave amplitude in these experiments. CONCLUSION: Photoplethysmography is the preferred method of assessing intestinal viability in the presence of ischaemia.
Anastomosis, Surgical↗
The use of infrared photoplethysmography in identifying early intestinal ischemia.
Acute intestinal ischemia and infarction remain serious clinical problems despite early operative intervention. An accurate and reproducible method of assessing ischemic tissue is critical to determine the precise limits of resection. The purpose of this study was to compare the utility of infrared photoplethysmography, intravenous fluorescein, and Doppler ultrasound in assessing intestinal ischemia in an operative canine model. After five segmental mesenteric arterial ligations in each of six conditioned dogs, the detection threshold for the limits of arterial perfusion of each modality was determined and correlated with the respective histopathologic specimens. Infrared photoplethysmography proved to be 100% sensitive for ischemia when its waveform amplitudes were 50% or greater of matched reference waveforms, whereas both intravenous fluorescein and Doppler ultrasound were 88% sensitive. All were comparably specific. We conclude that infrared photoplethysmography is comparable to intravenous fluorescein and Doppler ultrasound in the assessment of ischemic intestinal segments.
Animals↗
[Photoplethysmography (PPG) or photoreflexometry (PRM): principle and reproducibility (study of the validity of the method in healthy subjects)].
Photoplethysmography, a non-invasive vascular exploratory test, has recently made great in the evaluation of venous haemodynamics. The principle of Photoplethysmography uses the cutaneous reflection of infrared light in the intradermal venous plexi. Then methods are presented for a reliable implementation of the tests. Validity of the method is verified by applying statistical tests to measurements carried out in two healthy subjects. In conclusion, Photoplethysmography may be produced, providing that the method used is strict, that three successive measurements are carried out, so that only the mean value is considered; because of the low value of the variability index of the total filling time, this parameter is used in the interpretation of the method.
Female↗
Reflectance photoplethysmography as an adjunct to assessment of gravitational acceleration tolerance: preliminary findings.
We have examined the feasibility of using reflectance photoplethysmography to assess Gz acceleration tolerance. Reflectance plethysmograms recorded using a sensor placed on the region of the superficial temporal artery were analysed along with the mean value and the pulsatile component of the Doppler velocity recorded from the opposite temporal artery. The photoplethysmogram signal and pulsatile and mean Doppler velocities were examined as predictors of impending peripheral light loss (PLL) during the experiments. Photoplethysmography correctly predicted a large percentage of the PLL runs (80.5%) and non-PLL runs (98.3%). Mean Doppler velocity predicted a higher percentage of PLL runs (88.1%), but with an unacceptably low rate of non-PLL runs (77.2%). The pulsatile Doppler velocity yielded only 50.7% correct prediction of PLL runs. The results of this preliminary study indicate that, with an improved design of the sensor and the electronics, it may be possible to use reflectance photoplethysmography in acceleration tolerance experiments as a reliable predictor of impending peripheral light loss.
Acceleration↗
Green light photoplethysmography monitoring of free flaps.
BACKGROUND: Monitoring strategies have been developed to address the issue of detecting postoperative free flap ischemia in an effort to permit intervention and flap salvage. No one existing noninvasive method has been widely accepted in a clinical setting. Green light photoplethysmography (GLP) uses a diode to transmit green light into a tissue. Reflected light from hemoglobin in dermal capillary red blood cells is analyzed as light intensity along a frequency spectrum. A pure peak signal (1-2 Hz) is identified and provides a way to distinguish between perfused and nonperfused tissue. DESIGN: Prospective, blinded comparison. SUBJECTS: Sixty of 72 consecutive patients considered for free flap reconstruction were enrolled in a protocol to evaluate the efficacy of GLP. INTERVENTION: After free flap elevation, but before pedicle ligation, 120-second baseline measurements were obtained; 120-second measurements then occurred 5 minutes after the onset or release of individual venous or arterial occlusion. Signals were processed by fast Fourier transfer; a mean alternating current-direct current (AC/ DC) ratio was cultivated for each signal. All data were analyzed in a blinded fashion. RESULTS: The AC/DC ratio of GLP was statistically significant across all flap perfusion states (P<.001). Each condition resulted in a unique GLP signal within 5 minutes of manipulation of each vessel. CONCLUSIONS: Green light photoplethysmography with AC/DC ratio analysis provides a rapid, precise method with which to determine flap ischemia and can differentiate venous compromised and arterial compromised flaps almost immediately after the onset of an ischemic insult. It may provide a clinically useful tool for postoperative free flap monitoring.
Fourier Analysis↗