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At least 415 records · Page 23Linked to original sources
PubMed2000

Exhaled nitric oxide following repeated spirometry or repeated plethysmography in healthy individuals.

Subjects with asthma have higher concentrations of exhaled nitric oxide (NO) than normal individuals. It has been demonstrated that in asthmatics, repeated FVC maneuvers reduce NO. Although the cause of this phenomenon is not known, it has been hypothesized that deep breaths associated with FVC maneuvers reduce exhaled NO by affecting neural sources of NO, possibly via a mechanism related to the pathobiology of asthma. To establish whether FVC maneuvers influence NO concentrations in normal individuals, we measured exhaled NO at baseline values and after FVC maneuvers performed every 15 min for 1 h in subjects without asthma. To investigate the role of deep breaths in reducing exhaled NO, we compared these results with concentrations of exhaled NO after plethysmography. Repeated FVC maneuvers over 60 min produced a decrease in NO concentrations in mixed expired gas (F(E)NO; 24.6 +/- 5.1% decrease for F(E)NO, p < 0. 01 versus baseline). In contrast to the results after spirometry, repeated specific airway conductance (sGaw) maneuvers do not have a significant effect on F(E)NO (p = 0.16). These results, which demonstrate that in nonasthmatic subjects FVC maneuvers-but not panting maneuvers-produce a fall in NO, suggest that the mechanism responsible for the reduction in exhaled NO after FVC maneuvers is related to volume history of the lung rather than the pathobiology of asthma.

Adult↗
PubMed2000

Comparison of apnea identified by respiratory inductance plethysmography with that detected by end-tidal CO(2) or thermistor. The CHIME Study Group.

As part of the Collaborative Home Infant Monitoring Evaluation (CHIME) we compared apnea identified by a customized home monitor using respiratory inductance plethysmography (RIP) with simultaneously recorded polysomnography-acquired nasal end-tidal CO(2) (PET(CO(2))) and nasal/oral thermistor in 422 infants during overnight laboratory recordings to determine concordance between techniques, sources of disagreement, and capacity of RIP to detect obstructed breaths within an apnea. Among 233 episodes of apnea identified by at least one method as >/= 16 s, 120 were observed by the CHIME monitor, 219 by PET(CO(2)), and 163 by thermistor. The positive predictive value of the CHIME-identified apnea was 89.2% (95% CI 83, 95) and 73% (95% CI 65, 81) for PET(CO(2)) and thermistor, respectively. However, the sensitivity of the CHIME monitor in identifying events detected by the other methods was only approximately 50%. Among 87 apnea events identified by all three techniques, no two methods showed high agreement in measurement of apnea duration: RIP and PET(CO(2)) (ICC = 0.54), RIP and thermistor (ICC = 0.13), PET(CO(2)) and nasal thermistor (ICC = 0.41). Among the 179 breaths identified by RIP as obstructed, 79.9% were judged to be obstructed on the PET(CO(2)) and 80.4% were judged to be obstructed on the thermistor channel. Among 238 breaths identified on PET(CO(2)) as obstructed, 54.2% were determined to be obstructed by RIP. Among 204 breaths identified on thermistor as obstructed, 55. 4% were determined to be obstructed by RIP. Reasons for discrepancies in apnea detection among channels included body movement, partial airway obstruction, and obstructed breaths. Despite these limitations the CHIME monitor provides an opportunity to record physiological data previously unavailable in the home.

Apnea↗
PubMed1987

Evaluation of respiratory inductive plethysmography in infants weighing less than 1,500 grams.

Calibration of the respiratory inductive plethysmograph (RIP) was performed in premature infants weighing less than 1,500 g. In only 25% of the studies was an acceptable calibration achieved, as assessed by statistical comparison of simultaneously measured pneumotachygraph and RIP tidal volumes. In 6 infants, dead space loading or air injection was performed in an attempt to alter abdominal and rib cage volume contributions and thereby improve the calibration. Neither of these maneuvers resulted in an improvement of the accuracy of the RIP calibration coefficient. We conclude that, when calibrated by the least squares technique, the reliability of inductive plethysmography in measuring tidal volume in small infants is low. This is presumably because they have very small tidal volumes and highly compliant rib cages.

Female↗
PubMed1993

Tidal volume measurements in newborns using respiratory inductive plethysmography.

Respiratory inductive plethysmography (RIP) is a well-accepted noninvasive technology for monitoring breathing patterns in adults. Prior attempts to calibrate this device in babies have been fraught with technical difficulties, thereby limiting applications in this population. Recently, a new method, qualitative diagnostic calibration (QDC), has been shown to provide accurate calibration of tidal volume in adults. The QDC method is based upon principles of the isovolume maneuver and carried out during natural breathing without specialized respiratory maneuvers or postural changes. We calibrated RIP with QDC in the supine posture and compared tidal volume (VT) measured with RIP to VT by a face mask-pneumotachograph (PNT) in 21 healthy full-term newborns in supine and prone postures. Eleven of the babies were calibrated during active sleep and 10 in quiet sleep. The mean VT in the supine and prone postures were 19 and 25 ml, respectively. In the supine and prone postures, weighted mean difference between RIP (VT) and PNT (VT) and 95% confidence intervals were -0.05 ml (-0.27, 0.18) and -0.32 ml (-0.08, 0.55), respectively. There was no difference in the accuracy of RIP relative to PNT calibrated during active sleep when thoracoabdominal incoordination was present or quiet sleep when it was not in either the supine or the prone postures. Therefore, in full-term infants, RIP calibrated with QDC solely in the supine posture provides clinically acceptable measurements of VT in both supine and prone postures.

Analysis of Variance↗
PubMed1975

An improvement in whole body plethysmography.

A simple method for greatly reducing thermal drift and acoustic noise in constant-volume, whole body plethysmography is described. Evaluation and adjustment for any particular clinical application can be carried out in a few moments. The device itself consists of a 20- to 25-gauge needle, a "Y" tube, and a 1-liter or more vessel, and may be assembled in 30 minutes from parts readily available in any hospital laboratory.

Plethysmography, Whole Body↗
PubMed1981

Respiratory induction plethysmography (Respitrace): an evaluation of its use in the infant.

Respiratory Induction Plethysmography (RespitraceTM) is a recently described method for noninvasive respiratory monitoring in adults. We report here on its calibration and use in 15 infants. Tidal volume, as measured by this method, was compared with the tidal volume integrated from a pneumotachygraph attached to a tightly fitted face mask. The 2 volumes had a correlation greater than 0.85 (p less than 0.001) with a slope between 0.9 and 1.1. The results were similar in both quiet and rapid eye movement sleep demonstrating that the method can accurately follow paradoxical inward rib cage movement. However, the accuracy decreased at respiratory rates above 80 breaths/min. When the minute ventilation was computed over the same sampling interval by both methods, the mean difference was +0.2 +/- 3.4% (+/- 1 SD) in quiet sleep and +0.8 +/- 4.5% in rapid eye movement sleep. We concluded that this is an accurate method of measuring long-term minute ventilation and tidal volume in small infants, provided that both the calibration procedure and measurements are made in the same posture, and the infant's respiratory rate is less than 80 breaths/min.

Adult↗
PubMed1982

Monitoring smoking patterns of low and high tar cigarettes with inductive plethysmography.

We developed a nonobtrusive technique to measure the volume puffed during smoking. An inductive plethysmographic coli placed around the cheeks was calibrated by coaching the subject to take graded puffs from an unlit cigarette connected in series to a 2-L Krogh spirometer. The device had a linear volume response that was unaltered by smoking filtered or unfiltered cigarettes or by the length of the cigarette. It remained calibrated after smoking 4 cigarettes over 150 min. Ten subjects smoked a high tar content (HTC) and a low tar content (LTC) cigarette, each with and without a cigarette holder. The mean puff volume from LTC of 52 +/- 15 ml was significantly higher than HTC of 39 +/- 10 ml (p less than 0.001). The number of puffs per cigarette (8.4 +/- 2.1 for LTC, 8.3 +/- 2.0 for HTC), the volume of inhaled (841 +/- 517 ml for LTC and 748 +/- 323 ml for HTC), and the duration of inhalation and associated breathhold (5.5 +/- 2.6 s for LTC and 5.6 +/- 2.4 s for HTC) as measured by respiratory inductive plethysmography were comparable. The perception of intensity of inhalation by the subjects bore little relationship to the objective measurement. A cigarette holder increased the number of puffs per cigarette to 12.6 +/- 4.8 for LTC (p less than 0.02) and to 11.9 +/- 3.6 for HTC (p less than 0.01 and increased the puff volume for HTC to 50 +/- 12 ml (p less than 0.01) and the duration of inhalation to 6.6 +/- 2.5 s for LTC (p less than 0.005). These results show that (1) smokers switched acutely from HTC to LTC draw larger puffs from LTC thereby possibly circumventing the perceived benefits of smoking LTC, (2) cigarette holders modify smoking pattern and hence if used with an incorporated flowmeter to monitor the natural pattern of smoking might give spurious information.

Adult↗
PubMed1981

Venous plethysmography: measuring techniques and normal values.

A fixed procedure of strain gauge plethysmography in a control population aged between 20-30 years allows normal values for venous parameters (venous distensibility, emptying, and resistance) and capillary filtration coefficient, to be determined. High speed recording reveals two phases in venous emptying, one passive, purely elastic, and a second active phase, resulting from venous constriction.

Adult↗
PubMed1981

Venous plethysmography applied in pathologic conditions.

The correlation between venography and SGP in 41 patients was studied. Fourteen normal subjects were used as a reference. SGP was shown to be very sensitive (97.5%), including proximal and distal DVT, and highly specific (96.4%). After some recommendations for patient positioning and technical use, it will enhance both the accuracy and the reproducibility of plethysmography for evaluation of patients with suspected deep venous thrombosis.

Acute Disease↗
PubMed1983

Noninvasive assessment of the autonomic nervous tone in angina pectoris: an application of digital plethysmography with auditory stimuli.

To assess the relationship between autonomic nerve activity and the anginal attack, we examined the daily variation of the autonomic tones employing digital plethysmography with auditory stimuli, and also tested the daily variation of exercise capacity. Thirteen of 45 cases (28.9%) of spontaneous angina, excluding Prinzmetal's angina, complained of typical chest discomfort or pain especially in the morning. They manifested an augmented level of the autonomic nerve activity and positive stress testing. The remainder did not demonstrate these abnormal findings in the morning. For the 13 cases, calcium antagonists were given orally immediately after awakening. This resulted in the complete relief from chest discomfort or pain. These findings suggest that an autonomic imbalance plays an important role in the pathogenesis of this type of anginal attack. Thus, the estimation of the daily variation of autonomic nervous tone would be valuable for the diagnosis and treatment of angina pectoris.

Acoustic Stimulation↗
PubMed1987

Plethysmography: history and recent advances.

A short historical note on plethysmography is given and the development of the modern computerized pneumoplethysmograph is described. The computer-aided pneumoplethysmogram (CAP), with proper programming, makes possible numerous computations that give new, useful, and rapid information about the patient. New applications of the CAP will quickly develop and the data collected will be quickly analyzed and displayed.

Blood Flow Velocity↗
PubMed1987

Shortcomings of physical examination and impedance plethysmography in the diagnosis of lower extremity deep venous thrombosis.

Accuracy in the diagnosis of lower extremity deep venous thrombosis (DVT) by physical examination and impedance plethysmography (IPG) is reviewed. Physical examination proved unreliable in distinguishing patients with and without acute disease. Swelling in the leg was, however, more prevalent in patients with DVT. The sensitivity and specificity of IPG were less than those reported by other groups. Venography remains the most reliable diagnostic procedure in our institution.

Humans↗
PubMed1996

Surgical treatment of refractory venous stasis ulcer due to a severe impairment of calf muscle pump function: evaluation by air plethysmography. A case report.

The authors encountered a forty-nine-year-old man with a lower limb ulcer refractory to intensive conservative therapy. No varicose vein was found anywhere, and the usual phlebographies and foot venous pressure measurement failed to diagnose it as a venous stasis ulcer. A direct phlebography method developed by the authors, in which a thin catheter is inserted into the deep vein, disclosed a reflux of the popliteal vein or a deep muscle branch from which an incompetent perforator arose toward the superficial vein above the ulcer. Air plethysmography (APG) showed a severe impairment of the calf muscle pump function. He underwent a subfascial ligation of two incompetent perforators together with a stripping of the great saphenous vein passing under the ulcer. Postoperatively, this ulcer was cured in an early phase, and the calf muscle pump function showed improvement in the APG.

Hemodynamics↗
PubMed1999

Air plethysmography in chronic venous insufficiency: clinical diagnosis and quantitative assessment.

To define the role of air plethysmography (APG) in the clinical diagnosis and quantitative assessment of chronic venous insufficiency (CVI), APG studies were performed on 582 limbs in 291 patients with signs and symptoms of CVI. One hundred and thirty-one limbs were classified into group I (no evidence of CVI), 291 into group II (mild CVI), and 160 into group III (advanced CVI). On APG, the mean venous filling index (VFI) was 1.45 mL/s, 3.90 mL/s, and 5.25 mL/s in groups I, II, and III respectively (p<0.05). The mean ejection fraction (EF) and mean residual volume fraction (RVF) also showed significant differences between the limbs with CVI and the contralateral normal limbs, but the values were similar for the different severities of CVI limbs. The amount of overlap in VFI, EF, and RVF values among the clinical groups was considerable. Discrimination analysis derived a VFI value of 2.67 mL/s as a cutoff point between normal limbs and limbs with CVI, with a positive predictive value of 96%. In conclusion, APG is a simple and noninvasive test for quantitative assessment of the different components of CVI, valvular reflux, and calf muscle pump function. However, only VFI correlated significantly with the severity of CVI. VFI, with its high positive predictive value, may be useful in diagnosis of CVI, and it may serve as an objective quantitative measurement for monitoring the effect of treatment.

Air↗
PubMedDate not supplied

Bioelectrical impedance vs air displacement plethysmography and dual-energy X-ray absorptiometry to determine body composition in patients with end-stage renal disease.

BACKGROUND: Patients with end-stage renal disease (ESRD) have significant shifts in fluid homeostasis that may impair measurements of body composition using methods based upon determinations of body water. Estimates of body water are fundamental for bioelectrical impedance analysis (BIA), which measures electrical resistance to estimate total body water and body composition. METHODS: BIA was compared with 2 other techniques: (1) air displacement plethysmography (ADP), which relies on measurements of body density to estimate body fat and fat-free masses; and (2) dual-energy x-ray absorptiometry (DXA), which depends on the relative attenuation of an x-ray beam to produce images of body fat and bone mineral. In study 1, BIA and ADP were performed on 38 ESRD patients (21 men and 17 women; age 51.3 +/- 2.2 years; weight 79.8 +/- 2.9 kg; body mass index [BMI] 27.4 +/- 0.9 kg/m2). In study 2, BIA and DXA were performed on 47 patients (22 men and 25 women; age 52.7 +/- 2.3 years; weight 73.6 +/- 2.9 kg; BMI 25.9 +/- 1.0 kg/m2). RESULTS: The ranges of percent body fat using BIA in studies 1 and 2 were from 7% to 57% and from 6% to 52%, respectively. Percent body fat measurements were significantly (p < .0001) correlated for BIA vs ADP (r = .74) and for BIA vs DXA (r = .84). Mean body fat as determined by BIA and ADP in study 1 was 31.8 +/- 2.0% and 36.3 +/- 1.8%* and by BIA and DXA in study 2 was 29.6 +/- 1.5% and 31.8 +/- 1.8%*, respectively (*p < .05 vs BIA). All 3 methods had similar variability associated with their measurements (coefficients of variation approximately 5%). The average body fat measured by BIA was less than ADP or DXA, regardless of gender or race. Furthermore, the variation was not greater at lower or higher body fat values. CONCLUSIONS: Body fat measurements using ADP and DXA were correlated with those using BIA across a relatively wide range of body fat levels in adults with ESRD. However, BIA appeared to underestimate body fat and overestimate fat-free mass, possibly because of increased measurements of body water. Because ADP is convenient and does not use body water content in determination of body density and body composition, it has very good potential as a relatively new technique to estimate percent body fat in adults with ESRD.

Absorptiometry, Photon↗
PubMedDate not supplied

A comparison of air displacement plethysmography with three other techniques to determine body fat in healthy adults.

BACKGROUND: This study compared air displacement plethysmography (ADP), which relies on measurements of body density to estimate body fat, with three other techniques that measure body composition: (1) hydrostatic weighing (HW), which also measures body density; (2) bioelectrical impedance (BIA), which determines electrical resistance and total body water to estimate fat-free mass; and (3) dual-energy x-ray absorptiometry (DXA), which measures bone, fat, and fat-free soft tissue masses. METHODS: ADP, HW, BIA, and DXA were performed on 20 healthy volunteers (10 males and 10 females). The subjects were within 20% of ideal body weight, 31.1 +/- 1.8 years of age, and 75.4 +/- 2.7 kg with body mass index values of 25.2 +/- 0.9 (kg/m2) and percent body fat by ADP ranging from 6.0% to 41.0%. RESULTS: Percent body fat measurements by the four methods were highly correlated (r > .90, p < .0001). Mean body fat as determined by ADP, HW, BIA, and DXA were 23.4% +/- 2.3%, 23.9% +/-1.8%, 23.1% +/- 1.9%, and 26.4% +/- 2.4%, respectively (* p < .05 vs ADP). There was a significantly positive slope (+0.23) for the individual differences vs the average of ADP and HW percent body fat, demonstrating a slightly negative difference at lower body fat levels and a slightly positive difference at greater body fat levels. Although the average percent body fat determined by ADP was similar to that by HW for the entire population, there was a significant gender difference with the average body fat measured by ADP being 16% less in males and 7% greater in females than that determined by HW. CONCLUSIONS: Body fat measurements using ADP were highly correlated with those using HW, BIA, and DXA across a relatively wide range of body fat levels in healthy adults. These results support the utility of ADP as a relatively new technique in the estimation of percent body fat in healthy adults. However, the error associated with gender and the level of body fat is not negligible and requires further investigation.

Absorptiometry, Photon↗
PubMedDate not supplied

Ticlopidine in the treatment of multiple atherosclerotic arteriopathy: a strain gauge plethysmography and Döppler spectrum analysis evaluation.

The effect of ticlopidine was compared with flunarizine in patients with iliac-femoral and/or femoral-popliteal arteriosclerotic arteriopathy accompanied by lesions of the cervical arteries of no haemodynamic significance. In the lower limbs, plethysmography (strain gauge measurements) and Döppler ultrasonography integrated by spectral analysis of the cervical arteries showed qualitative and quantitative improvements of the regional haematic flow. Side-effects were negligible which suggests that ticlopidine is useful in the treatment of multiple arteriosclerotic arteriopathy.

Aged↗
PubMed1998

Forearm blood flow measured by venous occlusion plethysmography in healthy subjects and in women with postmastectomy oedema.

A chronic swelling of the arm may develop following damage to axillary lymph vessels during breast cancer treatment. Certain unusual pathophysiological features of postmastectomy oedema indicate that factors additional to lymphatic damage are important. One factor postulated previously is a haemodynamic abnormality. Forearm blood flow was therefore measured by venous occlusion plethysmography using both a conventional mercury strain gauge and a newer optical volumeter (Perometer). The latter was initially assessed in healthy subjects. When forearm blood flow was measured using the two methods simultaneously, the strain gauge and Perometer did not differ significantly for healthy or oedematous arms. Dominant and non-dominant arm blood flow in healthy subjects was similar but with greater variation between sides with the Perometer. Using the strain gauge, blood flow in the oedematous arm (2.51 +/- 1.33 ml/100 ml per min) was significantly lower than in the opposite unaffected arm (3.77 +/- 2.29 ml/100 ml per min; p = 0.026). The Perometer results showed a similar but nonsignificant trend (p = 0.105). Taking into account the greater limb volume on the affected side, total forearm blood flow was essentially the same in each arm (unaffected: 40.72 +/- 28.70 micromilligrams/min; oedematous: 41.78 +/- 22.11 ml/min). The reduced blood flow per unit volume of arm was therefore likely to be due to a simple 'dilution' effect of the increase in volume. The results indicate that it is unlikely that raised blood flow contributes to oedema formation, contrary to the haemodynamic concept.

Adult↗