Temperature corrections in routine spirometry.

Forced expiratory volume (FEV1) and forced vital capacity (FVC) were measured in nine normal subjects with three Vitalograph and three rolling seal spirometers at three different ambient temperatures (4 degrees C, 22 degrees C, 32 degrees C). When the results obtained with the rolling seal spirometer were converted to BTPS the agreement between measurements in the three environments improved, but when the Vitalograph measurements obtained in the hot and cold rooms were converted an error of up to 13% was introduced. The error was similar whether ambient or spirometer temperatures were used to make the conversion. In an attempt to explain the behaviour of the Vitalograph spirometers the compliance of their bellows was measured at the three temperatures. It was higher at the higher temperature (32 degrees C) and lower at the lower temperature (4 degrees C) than at the normal room temperature. These changes in instrument compliance could account for the differences in measured values between the two types of spirometer. It is concluded that the ATPS-BTPS conversion is valid and necessary for measurements made with rolling seal spirometers, but can cause substantial error if it is used for Vitalograph measurements made under conditions other than normal room temperature.     

Characteristics of the Vitalograph spirometer

The characteristics and performance of the Vitalograph dry spirometer were studied using the criteria suggested by the International Labour Organisation (I.L.O.) Report on the standardization of respiratory function tests in pneumoconiosis. Comparison was also made with the Bernstein spirometer. The recorder speed, activation volume, and accuracy of volume calibration and linearity comply with most of the suggestions in the I.L.O. Report. The combined resistance and inertia of the Vitalograph exceed the limits cited in the report, however, and are also greater than those reported for the Bernstein and other spirometers. Nevertheless, the Vitalograph calibrates well against the Bernstein for vital capacity and FEV₁ measurements made in normal subjects and in patients with obstructive airways disease. It is therefore suggested that it may be suitable for the assessment of forced expiratory volume and vital capacity in patients and normal subjects, or in population survey work. The fact that it is lightweight, portable, and robust is also an advantage.     

Effects of temperature on Vitalograph spirometer readings

Spirometric variables were obtained from nine symptomless subjects, who performed forced expiratory manoeuvres with three Vitalograph spirometers at three different ambient temperatures (36.5 degrees C, 24.1 degrees C, and - 7.3 degrees C) over three days according to a Latin square design. Analysis of variance showed no significant difference between values at different ambient temperatures when measured at ATPS. Correction of the results to BTPS resulted in a significant difference in values at the three ambient temperatures for all measurements other than the Vmax25. The mean error introduced by conversion to BTPS varied from 7% (SD 5%) for the FVC at 24.1 degrees C to 30% (21%) for Vmax50 at - 7.3 degrees C. Possible explanations for these observations include the increasing compliance of the spirometer bellows with increasing temperature, relatively slow cooling of gases within the spirometer, and a combination of these effects. We conclude that there is no evidence that conversion to BTPS improves the accuracy of measurements made on a Vitalograph spirometer. Further studies on other spirometers are needed to see whether conversion to BTPS is always appropriate.     

Evaluation of the turbine pocket spirometer.

A compact electronic spirometer, the turbine pocket spirometer, which measures the FEV1, forced vital capacity (FVC), and peak expiratory flow (PEF) in a single expiration, was compared with the Vitalograph and the Wright peak flow meter in 99 subjects (FEV1 range 0.40-5.50 litres; FVC 0.58-6.48 l; PEF 40-650 l min-1). The mean differences between the machines were small--0.05 l for FEV1, 0.05 l for FVC, and 11.6 l min-1 for PEF, with the limits of agreement at +/- 0.25 l, +/- 0.48 l, and +/- 52.2 l min-1 respectively. The wide limits of agreement for the PEF comparison were probably because of the difference in the technique of blowing: a fast, long blow was used for the pocket spirometer and a short, sharp one for the Wright peak flow meter. The FEV1 and FVC showed a proportional bias of around 4-5% in favour of the Vitalograph. The repeatability coefficient for the pocket spirometer FEV1 was 0.18 l, for FVC 0.22 l, and for PEF 31 l min-1. These compared well with the repeatability coefficients of the Vitalograph and the Wright peak flow meter, which gave values of 0.18 l, 0.28 l, and 27 l min-1 respectively. At flow rates of over 600 l min-1 the resistance of the pocket spirometer marginally exceeded the American Thoracic Society recommendations. The machine is easy to operate and portable, and less expensive than the Vitalograph and Wright peak flow meter combined. It can be recommended for general use.     

The accuracy of portable peak flow meters.

BACKGROUND: The variability of peak expiratory flow (PEF) is now commonly used in the diagnosis and management of asthma. It is essential for PEF meters to have a linear response in order to obtain an unbiased measurement of PEF variability. As the accuracy and linearity of portable PEF meters have not been rigorously tested in recent years this aspect of their performance has been investigated. METHODS: The response of several portable PEF meters was tested with absolute standards of flow generated by a computer driven, servo controlled pump and their response was compared with that of a pneumotachograph. RESULTS: For each device tested the readings were highly repeatable to within the limits of accuracy with which the pointer position can be assessed by eye. The between instrument variation in reading for six identical devices expressed as a 95% confidence limit was, on average across the range of flows, +/- 8.5 l/min for the Mini-Wright, +/- 7.9 l/min for the Vitalograph, and +/- 6.4 l/min for the Ferraris. PEF meters based on the Wright meter all had similar error profiles with overreading of up to 80 l/min in the mid flow range from 300 to 500 l/min. This overreading was greatest for the Mini-Wright and Ferraris devices, and less so for the original Wright and Vitalograph meters. A Micro-Medical Turbine meter was accurate up to 400 l/min and then began to underread by up to 60 l/min at 720 l/min. For the low range devices the Vitalograph device was accurate to within 10 l/min up to 200 l/min, with the Mini-Wright overreading by up to 30 l/min above 150 l/min. CONCLUSION: Although the Mini-Wright, Ferraris, and Vitalograph meters gave remarkably repeatable results their error profiles for the full range meters will lead to important errors in recording PEF variability. This may lead to incorrect diagnosis and bias in implementing strategies of asthma treatment based on PEF measurement.     

Effect of breathing circuit resistance on the measurement of ventilatory function

BACKGROUND: The American Thoracic Society (ATS) has set the acceptable resistance for spirometers at less than 1.5 cm H2O/l/s over the flow range 0-14 l/s and for monitoring devices at less than 2.5 cm H2O/l/s (0-14 l/s). The aims of this study were to determine the resistance characteristics of commonly used spirometers and monitoring devices and the effect of resistance on ventilatory function. METHODS: The resistance of five spirometers (Vitalograph wedge bellows, Morgan rolling seal, Stead Wells water sealed, Fleisch pneumotachograph, Lilly pneumotachograph) and three monitoring devices (Spiro 1, Ferraris, mini-Wright) was measured from the back pressure developed over a range of known flows (1.6-13.1 l/s). Peak expiratory flow (PEF), forced expiratory flow in one second (FEV1), forced vital capacity (FVC), and mid forced expiratory flow (FEF25-75%) were measured on six subjects with normal lung function and 13 subjects with respiratory disorders using a pneumotachograph. Ventilatory function was then repeated with four different sized resistors (approximately 1-11 cmH2O/l/s) inserted between the mouthpiece and pneumotachograph. RESULTS: All five diagnostic spirometers and two of the three monitoring devices passed the ATS upper limit for resistance. PEF, FEV1 and FVC showed significant (p < 0.05) inverse correlations with added resistance with no significant difference between the normal and patient groups. At a resistance of 1.5 cm H2O/l/s the mean percentage falls (95% confidence interval) were: PEF 6.9% (5.4 to 8.3); FEV1 1.9% (1.0 to 2.8), and FVC 1.5% (0.8 to 2.3). CONCLUSIONS: The ATS resistance specification for diagnostic spirometers appears to be appropriate. However, the specification for monitoring devices may be too conservative. PEF was found to be the most sensitive index to added resistance.     

Evaluation of a new electronic spirometer: the vitalograph "Escort" spirometer.

BACKGROUND--The "Escort" spirometer is a lightweight, hand held spirometer employing a Fleisch pneumotachograph. Measurements of forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and peak expiratory flow (PEF) are obtained from a single FVC manoeuvre. Results are displayed on a small liquid crystal display, but there is no graphical display. The performance of the Escort spirometer has been compared with that of a wedge bellows spirometer (Vitalograph S model) and a Wright PEF meter. METHODS--One hundred and thirteen subjects performed three FVC manoeuvres on the wedge bellows and Escort spirometers and three PEF manoeuvres on the Wright meter. The best reading for each index was recorded. In 21 of the subjects comparison of a Wright manoeuvre with an FVC manoeuvre on the Escort spirometer was performed, whilst in three subjects the effect of repeated blows was studied. RESULTS--The FEV1 ranged from 0.5 to 5.4 litres, FVC from 1.05 to 6.2 litres, and PEF from 100 to 725 l/min. The mean (SD) difference for the FEV1 was -0.05 (0.15) (95% confidence interval (95% CI) -0.07 to -0.02) litres, for FVC 0.03 (0.28) (95% CI -0.02 to +0.08) litres, and for PEF 1.68 (50.6) (95% CI -7.7 to +11.1) l/min. The differences were positively correlated with the mean reading for PEF and FVC but not for FEV1. The Wright PEF manoeuvre performed on the Escort produced significantly higher PEF readings (mean difference -22.9 litres). There was no significant effect of repeated FVC manoeuvres on any of the indices. CONCLUSIONS--The Escort spirometer compares extremely well with a wedge bellows spirometer for measurement of FEV1 and FVC, whilst yielding results of PEF from an FVC manoeuvre which are comparable to those obtained from a Wright meter. It can be recommended for use as a portable hand held spirometer.     

Powered Liposuction: An Evaluation of Currently Available Instrumentation

BACKGROUND: Over the past several years, powered liposuction instruments have become available to the dermatologic surgeon. These instruments all move the cannula forward and backward 2-12 mm with rapidity. This motion simulates the standard human movement of the cannula and facilitates movement through the tissue. Powered liposuction may help to prevent surgeon fatigue and has recently been shown to aid in the efficacy of fat removal. OBJECTIVE: To compare and contrast currently available powered liposuction instruments, to obtain objective engineering data on the instruments, and to compare the instruments when used on actual liposuction cases. METHODS: Five currently available powered liposuction systems were evaluated by the author. Each instrument was used with a 3 mm dual side port cannula on patients undergoing tumescent liposuction. An independent engineering firm, who collected objective measurements such as weight, stroke force, temperature, and vibration measurements on the instruments, evaluated the units. Noise measurements were obtained. RESULTS: Each of the five systems showed advantages and disadvantages. Important issues were the size and weight of the units, as well as whether they were driven electrically or pneumatically. Stroke force is variable (range 9.5-30 pounds). The noise of the units ranged between 60 and 87 dB. Vibration measurements varied from instrument to instrument. Units produced a variable amount of heat ranging from 77 degrees F to 102 degrees F. Most instruments are autoclavable, and one system is disposable. Build quality and reliability varied with the instrument. CONCLUSION: Instruments for powered liposuction have emerged in the last 2 years, with each instrument having distinct advantages and disadvantages. This article reviews five currently available powered liposuction instruments and presents objective measurements as well as the author's experience using the instruments.     

Spirometry in healthy men: a correlation with smoking and with mild symptoms.

Symptoms, smoking history, and variates taken from the forced expiratory manoeuvre were studied in a group of 271 healthy men attending a mass radiography unit. It was found that correlation of the forced expiratory ratio (FEV1/FVC) with the presence of mild or moderate respiratory symptoms was at least as satisfactory as that of technically more complicated measurements such as MEF50 and MEF75. In asymptomatic individuals those differences associated with smoking were the same for FEV1/FVC as for MEF75. Asymptomatic abnormalities of lung function were not observed. Simple measurements such as FEV1/FVC can therefore provide as much information from a forced expiratory manoeuvre to screen for early airways obstruction as MEF50 and MEF75.     

Impact of surgical treatment on respiratory muscle dysfunction in symptomatic hyperparathyroidism

HYPOTHESIS: We hypothesized that surgical treatment would improve respiratory muscle strength in symptomatic hyperparathyroidism (HPT). DESIGN: Prospective clinical trial. SETTING: A tertiary referral center. PATIENTS: Fifteen consecutive patients with symptomatic HPT and 10 with euthyroid multinodular goiter (control group) without a history of obstructive or restrictive lung disease. INTERVENTIONS: Forced vital capacity and forced expiratory volume in 1 second were measured before and 6 months after surgery to estimate respiratory muscle involvement. These measurements were compared with the reference values estimated individually in each patient. Mann-Whitney and Wilcoxon signed rank tests were used for statistical analysis, and P<.05 was considered statistically significant. MAIN OUTCOME MEASURES: Respiratory dysfunction in patients with symptomatic HPT, pulmonary function after parathyroidectomy, and the correlation between the preoperative serum parathyroid hormone and total serum calcium values and the impairment in pulmonary function. RESULTS: Preoperative forced vital capacity and forced expiratory volume in 1 second measurements were below the reference values in 11 (73%) and 9 (60%) patients, respectively. All the patients were normocalcemic, and forced vital capacity and forced expiratory volume in 1 second measurements significantly improved at postoperative month 6 (P = .001). No significant difference was detected in the control group. Improvement in pulmonary function correlated with preoperative serum calcium and parathyroid hormone values in patients with HPT (P<.05 and P<.001, respectively). CONCLUSIONS: Symptomatic HPT impairs inspiratory and expiratory components of respiratory function, and normalization of serum calcium levels after surgical treatment is associated with a significant improvement in lung function.     

Penetration injury of the hindfoot following intramedullary nail fixation of a tibial fracture

Technical errors during intramedullary nail insertion are not uncommon. We report a case of tibial guide wire penetration into the distal tibial articular surface, the talus and the calcaneus during insertion of the nail with the ankle dorsiflexed. This has not been reported in the past. Computerized tomogram was a useful tool in the diagnosis. This complication was associated with long-standing ankle pain, which however eventually settled. We advise frequent use of biplanar C-arm image during the insertion of the guide wire, the reamer and tibial nail into the medullary canal of the tibia or other long bones. None of these instruments should be forced through. Once the knobbed guide wire is exchanged to a straight guide wire, the wire should not be forced through or reamed over, and the nail should be introduced over the guide wire with caution. Early intraoperative identification and recording of this iatrogenic accident is necessary in order to explain the situation to the patient and modify treatment accordingly.     

Forced expiratory time--its reliability as a lung function test.

Three studies of factors affecting variability of forced expiratory time (FET) have been carried out. In the first, different observers or repeated measurements over a few minutes were shown to make no significant contribution to FET variability. Time of day was also relatively unimportant. In the second study, FET was shown to vary considerably more than peak flow rate, forced expiratory volumes, and mid expiratory flow rates over the course of five days. In the third study, FET was shown to correlate with other measurements of airways obstruction though the correlation coefficients were relatively low. The measurement of FET is thought to be too variable to be of practical use as a screening test for small airways disease, though its clinical value is not questioned.     

Accelerometry of Adductor Pollicis Muscle Predicts Recovery of Respiratory Function from Neuromuscular Blockade

Background: Residual paralysis increases the risk of pulmonary complications but is difficult to detect. To test the hypothesis that accelerometry predicts effects of residual paralysis on pulmonary and upper airway function, the authors related tests of pulmonary and pharyngeal function to accelerometry of adductor pollicis muscle in 12 partially paralyzed volunteers.

Methods: Rocuronium (0.01 mg/kg + 2-10 [mu]g [middle dot] kg-1 [middle dot] min-1) was administered to maintain train-of-four (TOF) ratios (assessed every 15 s) of approximately 0.5 and 0.8 over a period of more than 5 min. The authors evaluated pharyngeal and facial muscle functions during steady state relaxation and performed spirometric measurements every 5 min until recovery. Upper airway obstruction was defined as a mean ratio of expiratory and inspiratory flow at 50% of vital capacity of greater than 1. The TOF ratio associated with "acceptable" pulmonary recovery (forced vital capacity and forced inspiratory volume in 1 s of >=90% of baseline) was calculated using a linear regression model.

Results: At peak blockade (TOF ratio 0.5 +/- 0.16), forced inspiratory flow was impaired (53 +/- 19%) to a greater degree than forced expiratory flow (75 +/- 20%) with a mean ratio of expiratory and inspiratory flow at 50% of vital capacity of 1.18 +/- 0.6. Upper airway obstruction, observed in 8 of 12 volunteers, paralleled an impaired ability to swallow reported by 10 of 12 volunteers. In contrast, all volunteers except one could sustain a head lift for more than 5 s. The authors calculated that a mean TOF ratio of 0.56 (95% confidence interval, 0.22-0.71) predicts "acceptable" recovery of forced vital capacity, whereas forced inspiratory volume in 1 s was impaired until a TOF ratio of 0.95 (0.82-1.18) was reached. A 100% recovery of TOF ratio predicts an acceptable recovery of forced vital capacity, forced inspiratory volume in 1 s, and mean ratio of expiratory and inspiratory flow at 50% of vital capacity in 93%, 73%, and 88% of measurements (calculated negative predictive values), respectively.     

赛维皮肤检测仪皮肤颜色测定重复性研究--与日本美能达CD-2600分光光度计及德国MX-18红斑/黑素指数测量仪的对比研究

目的:将赛维皮肤检测仪皮肤颜色检测值分别与日本美能达CD-2600分光光度计及德国MX-18红斑/黑素指数测量仪检测值进行对比以检测赛维皮肤检测仪的重复性和相关性。方法:A:赛维皮肤检测仪与日本美能达CD-2600及德国MX-18的相关性:用三台仪器对10名健康女性志愿者的前臂内侧、外侧、手背、额、颧(均为左侧)共5个部位进行一次性检测。B:重复性:用三台仪器对5名健康女性志愿者的前臂内侧、手背、额(均为左侧)共3个部位进行3次重复定量检测,每次测量间隔5天。结果:赛维皮肤检测仪参数与美能达CD-2600/德国MX-18各参数之间呈较好的相关。重复测量显示赛维皮肤检测仪参数MI(表层和底层)、SBI(表层和底层)的变异系数(CV)明显小于日本美能达CD-2600及德国MX-18红斑/黑色素指数测量仪。结论:赛维皮肤检测仪能较客观准确反映不同部位皮肤色素的变化规律,具较好的重复性。     

Intrasubject variability of pulmonary function testing in healthy children.

The intrasubject variability of repeat pulmonary function testing was examined in 20 healthy children aged 10 to 16 years. The children were tested a maximum of 11 times over a period of two months. The tests examined were spirometry, maximum expiratory flow-volume curves, body plethysmograph determination of lung volumes, and single breath nitrogen washout. The time of day or the length of the re-test interval, up to a period of two months, did not significantly affect the variability. Standard deviation was used when comparing the variability of measurements with the same units and coefficient of variation was used when comparing measurements of different units. The vital capacity measured by spirometry was the least variable measurement. Functional residual capacity, residual volume and total lung capacity were equally reproducible but as a group were more variable than vital capacity. There was no significant difference between the variability of the following measurements: forced expired flow from 25 to 75% of the vital capacity, flows at 70%, 50% and 40% total lung capacity, and flows at 50% vital capacity. Flows at 25% vital capacity were significantly less variable than other measurements of flow. The variability of forced expired volume in one second was examined and the use of this measurement in determining significant bronchial hyper-reactivity was assessed.     

Correlation of ultrasound velocity in the tibial cortex,calcaneal ultrasonography,and bone mineral densitometry of the spine and femur

We compared the attributes of tibial cortex speed of sound (SOS) measurements with the SOS and broadband ultrasound attenuation (BUA) of the calcaneus, and bone mineral densities of the lumbar spine and femoral neck in a patient crossover study. The three instruments used in the crossover study were the LUNAR DPX and Achilles^TM, and a newly introduced device for measuring tibial cortical SOS, the SoundScan^TM 2000. Ultrasound precision determinations on the two instruments were performed with the same group of 10 volunteers, and the bone densitometry precision was derived from 22 patients who were assessed twice in a single visit, with repositioning between spine and hip scans. There were 220 female patients in the clinical study, 28 of whom had thoracic spine fractures, and all had measurements with the three instruments. Of the three instruments, the best precision, or lowest coefficient of variation and standardized coefficient of variation, was obtained with the SoundScan^TM 2000; 0.20% and 1.39%, respectively. The tibial SOS correlated more poorly with the lumbar spine and femoral neck bone mineral densities (BMDs) than the calcaneal parameters in 220 patients. Tibial SOS measurements could not distinguish the group with spinal fracture from an age-matched control group to aP<0.05 level, whereas the lumbar spine BMD and calcaneal BUA and stiffness showed a significant difference. We conclude that the SoundScan^TM 2000 system measures propagation of sound in the tibial cortex with great precision, but its role in clinical practice is moot. Yet to be established by a long-term prospective study is its efficacy in predicting fracture risk and how well it reflects bone change in response to treatment of osteoporosis.