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At least 451 records · Page 25Linked to original sources
PubMed1986

Breathing patterns in infants utilizing respiratory inductive plethysmography.

Respiratory inductive plethysmography (RIP) is a method that can be used to assess breathing patterns in infants without an airway connection. Ribcage and abdomen transducers are used which require gain factor calculation for calibration. We employed a single position graphic (SPG) calibration technique for gain factor calculation in RIP to obtain breathing pattern data for 70 infants in the quietly awake state. The SPG technique utilizes selection of two breaths from a 20s run of breaths with different ribcage/pneumotachograph (RC/PNT) and abdomen/pneumotachograph (AB/PNT) ratios for the gain factor calculation. Validation of gain factors was performed by comparing volumes obtained simultaneously by RIP and PNT. In 46 of the infants, maintenance of gain factor accuracy was confirmed following position reversal. Revalidation after position change could not be accomplished in 24 infants who were aroused into an agitated state. Breathing patterns were collected by RIP alone on the 46 infants who remained accurately calibrated in the supine and prone positions. No significant correlations were found between breathing pattern data and anthropometric characteristics. When the infants were repositioned, no consistent pattern of change could be identified. This study suggests that the SPG technique provides time-efficient and accurate calibration of RIP in the newborn infant. Furthermore, accuracy is maintained through position change if the infant remains in the same behavioral state. Breathing pattern data presented is representative of normative values in the quietly awake state for our study population.

Calibration↗
PubMedDate not supplied

[Development of a flexible cardiorespiratory monitor based on induction plethysmography].

Induction plethysmography (IP) utilizes changes in the inductance of sinusoidal wires embedded in elastic bands placed around the chest and abdomen to detect volume changes in the two compartments. These changes can be attributed to respiration or heart beat. To date, most applications have been tailored to an investigation of respiration. More sensitive systems have been employed for the detection of cardiac activity. The wires within the bands, which function as the coil in a resonant circuit, are excited by an oscillator. Among other factors, the inductance of the coil depends on the cross-sectional area of the coie, and changes with respiration in coils placed around the chest and abdomen. Using LabView software, the biosignals obtained undergo an analog-to-digital conversion prior to processing. The system was calibrated using the isovolume method. In 10 adults, IP was tested against a pneumotachograph (PNT) in different body positions (standing, sitting, supine, prone). Correlation between tidal volumes measured with IP and PNT was of r > or = 0.96 on average, recalibration being done after each change in position. The absolute mean error ranged between 3.7 and 8.5%, depending on body position. The smallest error (3.7%) and greatest agreement between the two methods was found in the supine position (93.3% of the IP measurements within +/- 10% of the PNT measurements). An IP application that could be used to collect data over the long term and which is in good agreement with PNT was developed by employing a "virtual instrument" (VI, LabView) for flexible data acquisition and data processing. Agreement was best when the volunteer adopted a supine position. A smaller correlation was found in standing or seated subjects. This might be due to the fact that in the latter two positions, the respiratory system may have more than 2 degrees of freedom, and thus cannot be adequately monitored by only two bands around the thorax and abdomen. Signals produced by cardiac activity were detectable on the surface of the body.

Adult↗
PubMed2006

Effect of clothing type on validity of air-displacement plethysmography.

The purpose of the study was to evaluate the validity of an air-displacement plethysmography system (AP) within the general population, while wearing (1) a racing-type swimsuit (AP(SS)) and (2) participant's personal undergarments (AP(UG)), against hydrodensitometry (HW). Fifty women and 50 men were measured for body volume, density, and fat percentage by HW and compared with AP(SS) and AP(UG). For women, AP(UG) and AP(SS) were similar, although significant differences (p < 0.001) were observed between AP(UG) and HW and between AP(SS) and HW. For men, there was no significant difference between AP(UG) and HW; however, significant differences (P < or = 0.01) were found between AP(UG) and AP(SS) and between AP(SS) and HW. The small discrepancy in measured values between AP and HW are within the measurement error for the instrumentation and these data support the use of AP for determination of body composition in adults across a wide range of body size (body mass index [BMI] 17.7-35.2 kg.m(-2)) and age (18-57 y). Participants' personal undergarments provide a practical alternative to a spandex swimsuit when measuring body composition by AP in women but not in men.

Adolescent↗
PubMed1977

Vascular responses in the human periodontal ligament and alveolar bone detected by photoelectric plethysmography: the effect of force application to the tooth.

A modification of the technique of photoelectric plethysmography has been developed to monitor changes in the microcirculation of the human periodontal ligament and adjacent alveolar bone, whereby detection is made of light reflected from or transmitted through a tissue during alterations in blood volume, flow or distribution. Light is conducted to and from the periodontal tissues via miniature fiberoptics placed within the root canals of endodontically treated teeth, or illuminated through the external surface of the gingiva towards the root. Circulatory activity was monitored both with the teeth at rest and under forces up to 480 gm. Horizontal and axial forces were found to produce a decrease in blood volume in the area of the periodontal tissue under compression. In an area under tension, an initial increase in blood volume was followed by a decrease as the magnitude of force rose above the critical 90 to 180 gm level. The pulse volume, however, was increased during both phases. Analysis of the biphasic and pulse volume changes suggests that autoregulation of blood vessel tone occurs in the periodontal tissues as a result of alteration in extravascular tissue pressure when the root is moved relative to the alveolus. It is proposed that this autoregulatory mechanism may play a role in alveolar bone metabolism by producing alteration in local tissue oxygen tension.

Adult↗
PubMed1999

Peripheral hemodynamics evaluated by acceleration plethysmography in workers exposed to lead.

To clarify the effect of lead exposure on peripheral hemodynamics, acceleration plethysmography (APG) was performed for 48 male subjects occupationally exposed to lead (exposure group) and 43 male subjects with no history of occupational exposure to lead (control group). In the exposure group, the blood lead concentration (Pb-B) was also measured. Each APG parameter was assessed by comparing measured data with the standard aging curves. A significant negative correlation was obtained between the parameter--b/a and Pb-B. The exposure group showed significantly lower values of parameters--b/a (p < 0.01) and d/a (p < 0.05) than the control group. The parameter--b/a in the exposure group dose-dependently decreased with increases in length of working career (duration of exposure to lead) and Pb-B. The parameter--b/a significantly (p < 0.05) decreased in subjects with working careers of 5 years or more and in subjects whose Pb-B was 40 micrograms/100 ml or more. These results suggest that lead exposure affects peripheral hemodynamics as evaluated by APG.

Adult↗
PubMed1980

Skin blood flow in normal pregnancy measured by venous occlusion plethysmography of the hand.

Total hand blood flow was measured by venous occlusion plethysmography in 14 healthy primigravid women. Consecutive measurements were made from the 15th week of pregnancy until term and after delivery. During pregnancy the mean hand blood flow, measured under standard resting conditions with the subjects supine, increased progressively from 7.7 in early pregnancy to 28.9 ml/100 ml/min at term. Simultaneously the peripheral vascular resistance decreased from 19.3 to 3.3 PRU100. When examined at 6--16 weeks after delivery hand blood flow and peripheral resistance were not yet returned to normal.

Adult↗
PubMedDate not supplied

Comparative measurements of the mucosal blood flow in the human maxillary sinus by plethysmography and by xenon.

Two different methods, one plethysmographic and one where the elimination of radioactive inert gas was measured, have been used to calculate the blood flow in the mucosa of the maxillary sinus in living man. A total of 5 persons were investigated and the mean values of the blood flow in the two methods showed a close correlation. Plethysmography is more easily performed and is therefore the preferable method to be used in studies on the physiology of the maxillary sinus.

Adult↗
PubMed1977

The influence of age on reactive hyperaemia in the human calf: a study with strain gauge plethysmography.

Postischaemic reactive hyperaemia in the calf was investigated by strain gauge plethysmography in four groups of ten subjects. The mean age of the different groups was 6, 13, 24 and 57 years respectively. Basal calf flow, repayment and recovery time in the 6-year-old children were greater than in the other groups, which may be related to a higher metabolic rate in young children. Maximal flow in the four groups was not significantly different, which indicates that the arteriolar response to circulatory arrest is not altered by increasing age. The cause of delay in maximal flow in the group of 6-year-olds is not clearly understood. Basal and postischaemic lowest peripheral resistance increased with age, which is probably caused by changes of the arterioles due to ageing and possibly inactivity. The fall in peripheral resistance induced by 3 min of ischaemia was positively correlated with mean blood pressure. This may be due to a greater net reduction in blood pressure during ischaemia, which brobably elicits a stronger myogenic response of the vessel wall. It is concluded that in clinical use of the reactive hyperaemia test in the calf, the influence of age is of minor importance, whereas postischaemic peripheral resistance is a more accurate measure of vasocilation for comparison of subjects with different blood pressure.

Adolescent↗
PubMed1986

Drug- and temperature-induced changes in peripheral circulation measured by laser-Doppler flowmetry and digital-pulse plethysmography.

We measured the effects of a new transdermal nitroglycerin patch (25 mg, 10 cm2) applied for 24 h, norphenephrine (6 mg), prazosin (1 mg) as well as local heat and cold provocation on blood pressure, heart rate, skin blood flow (measured by laser-Doppler flowmetry, L-D) and peripheral arterial resistance (assessed by digital pulse plethysmography, D-P) in 15 healthy volunteers (aged 21-31 years). Heat provocation induced a three-fold increase in skin blood flow in the hand (p less than 0.001) and cold provocation a decrease in flow (p less than 0.05) of about 20%. Forehead skin blood flow did not change. Peripheral arterial resistance showed less consistent changes during the provocation tests. Prazosin increased the forehead skin blood flow (p less than 0.01) and decreased peripheral arterial resistance, while norphenephrine showed an opposite effect. Transdermal nitroglycerin induced an increase of 25% in forehead skin blood flow (p less than 0.05) which persisted for 24 h and a decrease in peripheral arterial resistance (p less than 0.02), but this effect was evident up to 8 h only. We conclude that (1) local heat and cold provocation mainly affected skin blood flow, (2) vasodilative and vasoconstrictive drugs showed marked changes in peripheral arterial resistance, but at different points in time from subject to subject, and (3) transdermal nitroglycerin patches induced haemodynamic changes persisting for up to 8-24 h.

2-Hydroxyphenethylamine↗
PubMed1975

Oscillography and digital pulse plethysmography in occlusive disease of the subclavian artery and the brachiocephalic trunk. A pre- and postoperative study.

Patients with occlusive disease of the subclavian artery or brachiocephalic trunk were examined by oscillography (17 cases) and digital pulse plethysmography (19 cases) before and after reconstruction of the occluded vessel. Before surgery the oscillographic amplitudes were significantly lower on the occluded than the contralateral arm, with no difference between the registration levels. Shape analysis of the digital pulse curve recordings gave significant differences in all variables, between the occluded and the contralateral arm, inclination time and RAMP25 being most sensitive. Idential studies repeated up to 6 months after surgery demonstrated a marked increase in oscillometric amplitudes at all levels on the operated side. In the digital pulse-curve recordings the greatest improvement was found in inclination time and RAMP25.

Adult↗
PubMed1998

Determination of percent body fat by the newly developed sulfur hexafluoride dilution method and air displacement plethysmography.

The reliability and validity of two newly developed densitometric methods for determining the human body volume and percent body fat (%FAT), the sulfur hexafluoride dilution method (SHF) and air displacement plethysmography (ADP), were evaluated in comparison with the underwater weighing method (UWW). Seven healthy male volunteers (age 31 to 44, mean height 166.0 cm, weight 61.4 kg) participated in this study. The same-day test-retest coefficients of variation (CVs) for body volume and %FAT measurements were not significantly different among the three methods. SHF and UWW showed a strong correlation in terms of body volume and %FAT, with the correlation coefficients (r) being 0.9997 and 0.986, respectively. The correlation between ADP and UWW was slightly weaker (r = 0.9997 for body volume and 0.907 for %FAT). However, body volumes measured by SHF and ADP were significantly different from that by UWW when compared by mean values. Such differences were also found for %FAT measurements. The regression lines of body volume measured by SHF and ADP on that by UWW were almost equivalent to the line of identity. However, those of %FAT measured by SHF and ADP on that by UWW were significantly different from the line of identity. Because the reliability of SHF and ADP appeared to be high, further validation and improvement are required and worth doing.

Adult↗
PubMed2003

Airway obstruction after acute ozone exposure in BALB/c mice using barometric plethysmography.

BACKGROUND: Airway responsiveness after acute inhalation of ozone is related to the concentration and duration of ozone exposure. Using barometric whole-body plethysmography and increase in enhanced pause (Penh) as an index of airway obstruction, we measured the response of BALB/c mice to acute ozone inhalation to study the time course change of pulmonary function after ozone exposure. METHODS: Penh was measured before and after exposure to filtered air or 0.12, 0.5, 1, or 2 ppm ozone for 3 hr (n = 6/group). In addition, Penh was measured 24, 48 and 72 hr after ozone exposure. Bronchoalveolar lavage (BAL) and histopathologic examinations were performed. RESULTS: The increase in Penh after ozone exposure was significantly higher in the 0.12, 0.5, 1 and 2 ppm groups compared with the control group (all p < 0.01). Increases in Penh 24 hr after ozone exposure were significantly lower than those immediately after acute ozone exposure; however, increases in Penh 72 hr after ozone exposure were significantly higher than those in the control group (each p < 0.01). The proportion of neutrophils in BAL fluid was significantly higher in the group exposed to 2 ppm ozone than in the groups exposed to filtered air or 0.12 ppm ozone (both p < 0.01). CONCLUSION: These results indicate that airway obstruction is induced following ozone exposure in a concentration-dependent manner and persists for at least 72 hr.

Airway Obstruction↗
PubMed1990

Impedance plethysmography for surveillance of deep venous thrombosis following early discharge of total joint replacement patients.

Between April 1988 and February 1989, 877 patients undergoing total hip (394 patients) and total knee (483 patients) replacement surgeries were given warfarin prophylaxis perioperatively and were tested with impedance plethysmography (IPG) approximately 17 days postoperatively (10 days post-discharge) in the outpatient office. There were 69 positive IPG tests (7.8%). Further assessment of patients with positive IPG results using duplex scanning or venography confirmed DVT in 25 of the 69 patients (3.6%) in the popliteal or thigh areas, and ruled out venous disease in 44 patients. All 25 patients were readmitted for anticoagulation therapy with intravenous (IV) heparin and warfarin. There were no cases of pulmonary embolus. This study indicates that IPG testing is a safe and effective method of screening patients for DVT and its potentially fatal sequela of pulmonary embolus. Furthermore, IPG testing has proven to be cost effective, as it is a relatively simple procedure which can be administered by non-professional personnel in the outpatient office setting.

Aged↗
PubMed1981

Replacement of venography in suspected venous thrombosis by impedance plethysmography and 125I-fibrinogen leg scanning: a less invasive approach.

Noninvasive diagnostic testing is gaining acceptance in the evaluation of patients with clinically suspected venous thrombosis. Although clinically useful, all these tests have limitations, and the safety of basing therapeutic decisions on their outcome has not been assessed. We have done a prospective study of 322 symptomatic patients to ascertain the safety of replacing venography with impedance plethysmography and leg scanning. To provide a diagnostic reference, we did venography in all patients but withheld anticoagulants if the noninvasive tests were negative irrespective of the results of venography. None of the 163 patients with negative noninvasive tests died or developed clinical pulmonary embolism during 3 months' follow-up, confirming the safety of this approach. In two, clinically evident postvenographic venous thrombosis developed, confirmed by repetition of these objective tests. Also, the positive predictive values indicate that therapeutic decisions can be based on a positive noninvasive outcome in patients without clinical disorders known to produce false-positive results.

Adolescent↗
PubMed1992

The technique of occlusive-cuff impedance plethysmography. How to use this sensitive, noninvasive tool to detect proximal DVT.

Occlusive-cuff impedance plethysmography (IPG) is a rapid, reliable, and noninvasive method of diagnosing proximal deep venous thrombosis (DVT) in the lower extremities. The test is relatively easy to perform and carries an overall accuracy of greater than 90% when compared with venography. IPG is useful in detecting acute, symptomatic DVT and in determining the presence of recurrent DVT. In certain patients with nondiagnostic lung scans in whom pulmonary embolism is suspected, IPG may be helpful in determining appropriate therapy without use of pulmonary angiography.

Algorithms↗
PubMed1998

Re-evaluation of the role of impedance plethysmography in the diagnosis of deep vein thrombosis in surgical patients.

The clinical diagnosis of deep-vein thrombosis (DVT) is nonspecific and nonsensitive. As a result invasive and non-invasive laboratory tests are needed. In order to detect the diagnostic value of impedance plethysmography (IPG), a widely used non-invasive laboratory test, a prospective clinical trial was performed to compare IPG with color Doppler-ultrasonography (CDUS) and venography. Seventy-six (41 female, 35 male) high-risk abdominal surgery patients were included in the study. IPG and CDUS were performed preoperatively. During the postoperative period IPG, CDUS and venography were carried out. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of IPG were all determined. The preoperative IPG was positive in 32 patients, being (+) in 29 patients postoperatively. On the other hand, two of the 29 postoperative IPG (+) patients had DVT diagnosed postoperatively by CDUS and venography. One of 47 IPG (-) patients had DVT diagnosed postoperatively. According to these findings, the sensitivity of IPG was 67%, specificity 63%, and PPV, NPV and accuracy were 7%, 98% and 63%, respectively. Our study showed that IPG was not a reliable non-invasive laboratory method in the diagnosis and screening of DVT of the lower extremity.

Abdomen↗
PubMed1999

Airway reactivity measured by barometric whole-body plethysmography in healthy cats.

OBJECTIVE: To assess the validity of barometric whole-body plethysmography (BWBP) as a means of monitoring airway responses to induced bronchoconstriction in healthy cats. ANIMALS: 8 healthy cats without history of bronchopulmonary disease or exposure to indoor tobacco smoke. PROCEDURE: Cats were placed into a barometric plethysmograph with an internal volume of 38 L, and air flow was recorded at baseline and after carbachol (concentrations 0.005, 0.01, 0.02, 0.05, 0.1, and 0.2%) was introduced into the chamber. A dose-response curve was generated for several flow-derived measurements, and airway reactivity was determined by interpolation of the dose-response curve for enhanced pause. RESULTS: Peak inspiratory and expiratory flows increased significantly, but respiratory rate, inspiratory and expiratory times, relaxation time, and tidal volume did not differ significantly from baseline values. Flow-derived measurements (pause, enhanced pause, and end-expiratory pause) increased significantly at carbachol concentrations > 0.02%. Baseline measurements did not correlate with indices of airway reactivity. CONCLUSIONS AND CLINICAL RELEVANCE: Airway reactivity can be measured by use of BWBP, which is noninvasive. Airway reactivity was highly variable among cats and was not a function of baseline airway caliber, suggesting that other intrinsic mechanisms may be important.

Animals↗