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PubMedDate not supplied

Bronchial responsiveness in asthmatic children aged 3 to 8 years measured by forced pseudo-random noise oscillometry.

With the forced pseudo-random noise oscillation technique (FOT), resistance (Rrs) and reactance (Xrs) of the respiratory system can be measured simultaneously over a frequency spectrum of 2-26 Hz. As only passive cooperation of the child is needed, FOT is suitable for lung function measurements from the age of 2 1/2 years. Hence bronchial responsiveness can be measured in children who are not yet able to perform spirometry or flow-volume curves. We compared bronchial responsiveness to histamine and methacholine obtained with FOT. Threshold dose or provocative dose to histamine and methacholine showed a close correlation in asthmatic children aged 3.6 to 7.8 years. The 24 hour interval within-subject reproducibility of threshold dose and provocative dose to histamine in asthmatic children aged 3.9 to 8.5 years proved to be good. Bronchial responsiveness to histamine or methacholine measured by FOT was not influenced by baseline lung function or by bronchial smooth muscle tone.

Asthma↗
PubMed1990

Accuracy of four indirect methods of blood pressure measurement, with hemodynamic correlations.

In 38 adults undergoing cardiac surgery, 4 indirect blood pressure techniques were compared with brachial arterial blood pressure at predetermined intervals before and after cardiopulmonary bypass. Indirect blood pressure measurement techniques included automated oscillometry, manual auscultation, visual onset of oscillation (flicker) and return-to-flow methods. Hemodynamic measurements or calculations included heart rate, cardiac index, stroke volume index, and systemic vascular resistance index. Indirect and intraarterial blood pressure values were compared by simple linear regression by patient and measurement period. Measurement errors (arterial minus indirect blood pressure) were calculated, and stepwise regression assessed the relationship between measurement error and heart rate, cardiac index, stroke volume index, and systemic vascular resistance index. Indirect to intraarterial blood pressure correlation coefficients varied over time, with the strongest correlations often occurring at the first and last measurement periods (preinduction and 60 minutes after cardiopulmonary bypass), particularly for systolic blood pressure. Within-patient correlations between indirect and arterial blood pressure varied widely--they were consistently high or low in some patients. In other patients, correlations were especially weak with a particular indirect blood pressure method for systolic, mean, or diastolic blood pressure; in some cases indirect blood pressure was inadequate for clinical diagnosis of acute blood pressure changes or trends. The mean correlations between indirect and direct blood pressure values were, for systolic blood pressure: 0.69 for oscillometry, 0.77 for auscultation, 0.73 for flicker, and 0.74 for return-to-flow; for mean blood pressure: 0.70 for oscillometry and 0.73 for auscultation; and for diastolic blood pressure: 0.73 for oscillometry and 0.69 for auscultation. The mean measurement errors (arterial minus indirect values) for the individual indirect blood pressure methods were, for systolic: 0 mm Hg for oscillometry, 9 mm Hg for auscultation, -5 mm Hg for flicker, 7 mm Hg for return-to-flow; for mean: -6 mm Hg for oscillometry, and -3 mm Hg for auscultation; and for diastolic: -9 mm Hg for oscillometry and -8 mm Hg for auscultation. Mean measurement error for systolic blood pressure was thus least with automated oscillometry and greatest with manual auscultation, while standard deviations ranging from 9 to 15 mm Hg confirmed the highly variable nature of single indirect blood pressure measurements. Except for oscillometric diastolic blood pressure, a combination of systemic hemodynamics (heart rate, stroke volume index, systemic vascular resistance index, and cardiac index) correlated with each indirect blood pressure measurement error, which suggests that particular numeric ranges of these variables minimize measurement error.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1994

Comparison of arterial tonometry with radial artery catheter measurements of blood pressure in anesthetized patients.

BACKGROUND: Arterial tonometry has been introduced for continuous noninvasive measurement of blood pressure. The accuracy of this method depends on the performance of two components: a piezoelectric crystal array and an oscillometric cuff. This study evaluates overall performance of arterial tonometry in terms of the performance of these two components by comparing it with simultaneous recording of blood pressure from an intraarterial catheter. METHODS: Seventeen adult patients were studied during general anesthesia. Blood pressure was measured with an intraarterial catheter and with an arterial tonometry system. Analog pressure waveforms were sampled at 100 Hz. Blood pressure measurements obtained by oscillometry were recorded by computer. Comparisons of mean blood pressure on a beat-by-beat basis were made with and without correction for the calibration error introduced by oscillometry. RESULTS: The difference between pairs of blood pressure determined by arterial tonometry and intraarterial measurement was 1.3 +/- 9.4 mmHg (mean +/- SD, bias +/- precision) with 88,158 pairs of measurements. The difference between blood pressure determined by oscillometry and intraarterial measurement was 2.4 +/- 7.5 mmHg (mean +/- SD) with 401 comparisons. After correcting for calibration error, the difference between the tonometry measurements and intraarterial measurements was -1.0 +/- 5.6 mmHg. Continuous episodes of discrepancy from intraarterial measurements in excess of 10 mmHg and lasting 5-60 s occurred 4.6 +/- 0.8 times per hour with tonometry and 12.6 +/- 1.4 times per hour with oscillometry. CONCLUSIONS: Discrepancies in blood pressure readings by arterial tonometry versus intraarterial measurement result from both the piezoelectric crystal array and the oscillometry used for calibration. Accuracy for individual measurement is inferior to oscillometry alone. The ability to detect significant changes of blood pressure more rapidly than with oscillometry alone is limited by the accuracy of the piezoelectric crystal component but is enhanced by the reduced interval between measurements.

Adult↗
PubMed1996

Radial artery tonometry: moderately accurate but unpredictable technique of continuous non-invasive arterial pressure measurement.

Radial artery tonometry provides continuous measurement of non-invasive arterial pressure (CNAP) by a sensor positioned above the radial artery. An inflatable upper arm cuff enables intermittent oscillometric calibration. CNAP was compared with invasive radial artery pressure recordings from the opposite wrist in 22 high-risk surgical patients with an inter-arm oscillometric mean arterial pressure difference < or = 10 mm Hg. Oscillometric, tonometric and invasive digital pressure values, and invasive and CNAP waveforms were obtained by the same instrument (Colin BP-508). Correlation coefficients (r) of invasive vs oscillometric values (n = 481 pairs) were 0.83, 0.90 and 0.92, and mean absolute errors of oscillometry were 7.6, 4.7, and 2.6 mm Hg for systolic, diastolic and mean arterial pressures, respectively. Correlation was poor for systolic (r = 0.80), diastolic (r = 0.77) and mean (r = 0.84) invasive vs CNAP values (n = 1375). Compared with oscillometry, mean absolute errors of 15.2, 10.9 and 9.4 mm Hg for systolic, diastolic and mean CNAP, respectively, were significantly (P < 0.001) higher. Mean prediction errors of CNAP, compared with invasive values, were -5.8 (SD 14.2) mm Hg for systolic, +7.2 (8.3) mm Hg for diastolic and +3.9 (8.8) mm Hg for mean arterial pressure. Individual patient accuracy of CNAP was assessed as good (individual prediction error < or = 5 (8) mm Hg and individual absolute error < or = 10 mm Hg) in seven patients, as acceptable (< or = 10 (12) and < or = 15 mm Hg) in 11 patients, and as inadequate in four of 22 patients. Individual accuracy of oscillometry was good or acceptable in all 22 patients. The trend in CNAP changes (difference between consecutive measurements) was sufficiently accurate during induction of anaesthesia, as only 47 (7.6%), 14 (2.3%) and 27 (4.4%) of 616 systolic, diastolic and mean CNAP values differed by more than 10 mm Hg of invasive pressure trends. We conclude that: intermittent oscillometry provides accurate arterial pressure monitoring; CNAP measurements offer a reliable trend indicator of pressure changes during induction of anaesthesia and may be considered an alternative to invasive pressure measurements, should arterial cannulation be difficult in an awake patient; and accuracy of absolute CNAP values is only moderate and unpredictable, thus radial artery tonometry should not replace invasive monitoring in high-risk patients during major surgical procedures.

Adult↗
PubMed2004

Faster oscillometric manometry does not sacrifice the accuracy of blood pressure determination.

Faster oscillometry enables one to track rapid pressure changes. We therefore examined whether it was possible to shorten the measurement time without sacrificing accuracy. We accelerated and linearized cuff deflation and determined systolic and diastolic pressure values by the appearance and disappearance of oscillometric waves based on the interpolated cuff pressure-oscillometric wave amplitude relationship. The accuracy of faster oscillometry was examined by comparing correlations between invasive radial and oscillometric brachial pressure with either the conventional or the faster oscillometry in 23 patients (32+/-16 measurement pairs). Faster oscillometry shortened the measurement time from 27.7+/-3.5 s to 17.1+/-2.6 s. Neither pressure levels nor heart rate altered the time required for measurement. Bland-Altman analysis indicated that mean and standard deviation of difference between oscillometric and invasive systolic pressure was comparable (conventional, 2.1+/-7.5 mmHg; faster, 1.4+/-7.3 mmHg) without correlations between difference and average of systolic pressure. Similar differences (conventional, 5.0+/-6.8 mmHg; faster, 4.9+/-5.8 mmHg) and lack of correlations were also found for diastolic pressure. In conclusion, we succeeded in shortening the oscillometric measurement time to approximately 60% of the original time without sacrificing accuracy. This was achieved by acceleration and linearization of cuff deflation and by interpolation of the relationship between cuff pressure and oscillometric wave amplitude.

Adolescent↗
PubMedDate not supplied

Theory of the oscillometric maximum and the systolic and diastolic detection ratios.

It is proposed that the maximum in cuff pressure oscillations during oscillometry is due to the buckling of the brachial artery under a cuff. This theory is investigated by means of a mathematical model of oscillatometry that includes the mechanics of the occlusive arm cuff, the arterial pressure pulse waveform, and the mechanics of the brachial artery. A numerical solution is provided for the oscillations in cuff pressure for one cycle of cuff inflation and deflation. The buckling pressure is determined from actual arterial data and the von Mises buckling criteria. The buckling of an artery under a cuff occurs near -2 to 0 mm Hg transmural pressure. This effect corresponds with a maximum arterial compliance and maximum cuff pressure oscillations when cuff pressure is nearly equal to mean arterial pressure (MAP), in support of the suggested theory. The model was also found to demonstrate the basic characteristics of experimental oscillometry, such as an increasing and decreasing amplitude in oscillations as cuff pressure decreases, the oscillations that occur when cuff pressure is above systolic pressure, maximum oscillation amplitudes in the range of 1 to 4 mm Hg, and an oscillatory maximum at cuff pressure equal to MAP. These findings support the case that the model is representative of oscillometry. Finally, the model predicted values for the systolic and diastolic detection ratios of 0.593 and 0.717, respectively, similar to those found empirically. These ratios alter with blood pressure, but the tightness of the cuff wrap did not change their value.

Bias↗
PubMed2003

Reduction of interference in oscillometric arterial blood pressure measurement using fuzzy logic.

In oscillometry, oscillation amplitudes (OAs) embedded in the cuff pressure are drastically affected by a variety of artifacts and cardiovascular diseases, leading to inaccurate arterial blood pressure (ABP) measurement. The purpose of this paper is to improve the accuracy in the arterial pressure measurement by reducing interference in the OAs using a recursive weighted regression algorithm (RWRA). This method includes a fuzzy logic discriminator (FLD) and a recursive regression algorithm. The FLD is used to reduce the effect of artifacts caused by measurement motion disturbance or cardiovascular diseases, and to determine the truthfulness of the oscillation pulse. According to the truth degree, the relationship between the cuff pressure and OA is reconstructed using the regression algorithm. Because the regression method must utilize inverse matrix operation, which will be difficult to implement in an automatic or ambulatory monitor, the recursive regression method is proposed to solve this problem. To test the performance of this RWRA, 47 subjects underwent the ABP measurement using both the auscultation and the oscillometry combined with the RWRA. It was found that the average difference between the pooled blood pressures measured by the auscultation and those by the oscillometry combined with the RWRA was found to be only 4.9 mmHg. Clinical results demonstrated that the proposed RWRA is more robust than the traditional curve fitting algorithm (TCFA). We conclude that the proposed RWRA can be applied to effectively improve the accuracy of the oscillometric blood pressure measurement.

Adolescent↗
PubMed2005

Measuring bronchodilation in COPD clinical trials.

AIMS: The aim of this study was to compare the variability and sensitivity of impulse oscillometry (R5, X5 and RF), plethysmography (Raw and sGaw) and spirometry (FEV1, FVC and MMEF) in order to determine the most powerful technique for assessing bronchodilation in COPD clinical trials. METHODS: Twenty-four patients with COPD had impulse oscillometry, plethysmography and spirometry measured twice 30 mins apart, to determine variability. Then ascending doses of salbutamol (20, 50, 100, 200, 400 and 800 microg) were given and the same measurements made after each dose. Significant changes greater than variability were determined for each performed measurement (expressed as mean percentage improvement with 95% CI). RESULTS: Significant effects (P < 0.05) were detected after 20 microg by X5 (18.5% CI 9.8-27.2) RF (11.1% CI 7.2-15.0) and sGaw (21.5% CI 10.1-32.9), and after 50 microg by R5 (16.7% CI 10.8-22.5) and Raw (19.7% CI 13.0-26.4). FEV1 was less sensitive, detecting significant bronchodilation at 100 microg (10.2% CI 7.4-12.9). CONCLUSIONS: We conclude that impulse oscillometry and plethysmography should be considered the preferred techniques for measuring bronchodilation in COPD clinical trials.

Albuterol↗
PubMed2005

Automated oscillometric determination of the ankle-brachial index provides accuracy necessary for office practice.

Peripheral arterial disease (PAD) remains underdiagnosed by primary care and cardiovascular physicians. The office-based assessment of PAD is limited by the need for specialized equipment and the time required for performance of the ankle-brachial index (ABI). We explored whether the accuracy of automated ABI measurement by oscillometry compared favorably with the gold-standard method using continuous-wave Doppler ultrasound. Consecutive patients referred to our university hospital noninvasive vascular laboratory for ABI measurement were invited for participation. Of 205 patients, 201 participated, including 55 with PAD. The ABI was measured by automated oscillometry and Doppler ultrasound. The test of trends revealed a correlation coefficient of 0.78 in the left leg and 0.78 in the right leg (P<0.01 for both). The mean ABI difference between methods was 0.04+/-0.01 and 0.06+/-0.01, respectively, in the left and right legs. The differences between the methods followed a normal distribution. Oscillometric determination of the ABI provides an accurate determination of the ABI in an outpatient population. Our findings show automated oscillometry to be a reliable and easier method of ABI measurement, lowering the barrier to incorporation of this diagnostic test into clinical practice.

Aged↗
PubMed1999

Clinical comparison of three methods to measure blood pressure in nonsedated dogs.

OBJECTIVE: To determine arterial blood pressure in client-owned dogs, using direct arterial puncture, oscillometry, and Doppler ultrasonography in a clinical setting. DESIGN: Prospective study. ANIMALS: 8 clinically normal client-owned dogs. PROCEDURE: Blood pressures of nonsedated dogs were measured simultaneously, using each of the 3 methods. Mean values obtained were compared with published mean values. Ability of noninvasive methods (Doppler ultrasonography and oscillometry) to accurately predict results of the invasive method, and relationships between blood pressure and age, body weight, and degree of patient anxiety were determined. RESULTS: Calculated ranges of values (mean +/- 2 SD) determined by direct arterial puncture were: systolic pressure, 114 to 194 mm Hg; diastolic pressure, 66 to 102 mm Hg; and mean pressure, 85 to 129 mm Hg. Ranges determined by use of oscillometry were: systolic, 110 to 190 mm Hg; diastolic, 35 to 107 mm Hg; and mean, 78 to 138 mm Hg. Ultrasonographic and oscillometric values did not accurately predict direct values, but mean values of systolic and mean pressures were similar among methods. Relationships were not detected between age or body weight and blood pressure. Significant differences in blood pressure were not detected between anxious and nonanxious dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Mean values of systolic, diastolic, and mean arterial blood pressure measured in nonsedated client-owned dogs, using invasive and noninvasive methods in a clinical setting, are comparable with those determined for acclimatized, trained, or sedated dogs. However, results of noninvasive methods may not accurately reflect direct values.

Animals↗
PubMed2002

Monitoring arterial blood pressure during whole body hyperthermia.

BACKGROUND: For monitoring of arterial blood pressure (ABP) during whole body hyperthermia (WBH) different methods have been recommended. This investigation was performed to evaluate the agreement of invasive measurements at various sites, and to compare invasive and non-invasive methods of ABP monitoring under conditions of a heat-induced extreme vasodilation. METHODS: In 19 patients, 48 treatments with WBH were performed. Measurements of ABP in the radial and femoral artery by oscillometry and by sphygmomanometry were taken at four temperature levels during WBH (37, 40, 41.8 and 39 degrees C). RESULTS: Significant differences were observed between invasive and non-invasive methods for systolic ABP, with higher values for non-invasive measurements. When compared with both invasive measurements for diastolic blood pressures, sphygmomanometry gave higher values and oscillometry gave lower values. Sphygmomanometry also showed higher values for mean ABP compared with all other techniques, while measurements in radial and femoral artery and by oscillometry only differed by approximately 5 mmHg. CONCLUSION: The mean arterial pressure and not the systolic and/or diastolic pressure should guide hemodynamic management during WBH. The sphygmomanometric technique is not recommended for use during hyperthermia.

Adult↗
PubMed2004

Oral airway resistance during wakefulness in eucapnic and hypercapnic sleep apnea syndrome.

The purpose of this study was to evaluate whether there was an abnormal increase of upper airway resistance in the sitting and supine positions in hypercapnic obstructive sleep apnea syndrome (OSAS) patients compared with eucapnic OSAS or normal controls as measured by impulse oscillometry (IOS) while awake. Twenty subjects without OSAS served as controls (group I), and 20 patients with moderate or severe eucapnic OSAS (group II) and another eight hypercapnic severe OSAS patients (group III) were studied. Group II was further divided into two subgroups. Group IIa consisted of 14 subjects whose BMI was less than 35 and group IIb of six subjects whose BMI was greater than 35. All subjects also had an overnight sleep study. Oral airway resistance (AR) (including impedance (Zrs), resistance (R) and reactance (X)) was measured by impulse oscillometry (IOS) (MasterScreen IOS, VIASYS Healthcare GmbH, Germany) in the upright (seated) position and then in the supine position while awake. The results demonstrated that in both group I and group II, Zrs was normal in the sitting position. However, there was a high Zrs in the supine position for group II patients. In contrast, in group III patients, there was a high Zrs in both the sitting and supine positions. In conclusion, upper airway resistance was increased both sitting and supine in the hypercapnic OSAS patients; this would presumably increase the work of breathing and might explain why these subjects were hypercapnic while awake, while eucapnic OSAS patients and normal controls were not. Secondly, the increased upper airway resistance in the supine position in the eucapnic OSAS patients may contribute to their OSAS.

Adult↗
PubMed2001

Is oscillometric ankle pressure reliable in leg vascular disease?

The objective of the study was to evaluate the validity of oscillometric systolic ankle pressure in symptomatic leg arterial occlusive disease. Ankle pressure measurements using oscillometric curves obtained using a standard 12-cm cuff with a specially designed device for signal processing were validated against the continuous wave (CW) Doppler technique. Thirty-four subjects without signs or symptoms of peripheral vascular disease (68 legs) and 47 patients with leg ischaemia (85 legs) varying from moderate claudication to critical ischaemia were examined. The oscillometric curves were analysed using several algorithms reported in the literature, based on the assumption that maximum oscillations are recorded near mean arterial pressure. In normals, reasonable agreement between CW Doppler and oscillometric methods was seen. When an algorithm that determined the lowest cuff pressure at which maximum oscillations occurred, and a characteristic ratio for systolic pressure of 0.52 was used, the mean difference between CW Doppler and oscillometry was 1.7 mmHg [range -19 to +27, limits of agreement (2 SD) 21.1 mmHg]. In ischaemic legs, oscillometry overestimated systolic ankle pressure by a mean of 28.8 mmHg [range -126 to +65, limits of agreement 82.8 mmHg]. The difference was more pronounced among patients with critical ischaemia compared with claudicants, and also more evident among diabetics. The error of oscillometric pressure determination in subjects with leg arterial disease inversely increased with CW Doppler ankle pressure. In 39% of the recordings in legs with a CW Doppler systolic pressure below 100 mmHg, the oscillometric mean arterial pressure was higher than the recorded CW Doppler systolic pressure. In conclusion, the oscillometric method to determine systolic ankle pressure, based on the concept of maximum cuff oscillations occurring near mean arterial pressure, is not reliable in leg arterial disease, usually overestimating ankle pressure.

Aged↗
PubMed2005

Use of reactance to estimate transpulmonary resistance.

This study examines the relationship of respiratory system resistance (R(rs)) and reactance (X(rs)) measured by forced oscillometry with transpulmonary resistance (R(L)) measured by oesophageal manometry. Simultaneous forced oscillometry using a single frequency of 5 Hz and oesophageal manometry were performed on five asthmatics during bronchoprovocation. The data obtained were used to derive prediction equations for R(L) from oscillometric parameters, which were tested on a further six asthmatics and 35 nonasthmatic subjects. In the first five asthmatic subjects, R(L) correlated more strongly with X(rs) than with R(rs). In the second set of asthmatics, R(L) ranged 0.0005-4.57 kPa.s.L(-1), with a median of 0.21 kPa.s.L(-1). The R(L) values predicted from X(rs) showed a mean+/-sd difference of -0.067+/-0.25 kPa.s.L(-1) compared with the values measured in this set of patients. X(rs) in subjects with other respiratory conditions appeared to follow the same relationship with R(L) as in asthmatics. Lumped element modelling suggested that the linear relationship between X(rs) and R(L) was a consequence of the increasing contribution of central and upper airway wall shunts as peripheral airway resistance rose, and that this effect was much larger than that due to changes in static elastance. In conclusion, the reactance of the respiratory system can predict transpulmonary resistance more accurately than can the resistance of the respiratory system.

Adult↗
PubMed2006

Accuracy of an oscillometric blood pressure monitor during phenylephrine-induced hypertension in dogs.

OBJECTIVE: To examine the agreement between direct arterial blood pressure measurements obtained from 2 arteries and indirect blood pressure measurements obtained with an oscillometric blood pressure monitor (OBPM) during normotension and phenylephrine-induced hypertension in dogs. ANIMALS: 16 male Beagles. PROCEDURES: In anesthetized dogs, arterial catheters were placed in the lingual and dorsal pedal arteries for measurement of arterial blood pressure. A blood pressure cuff was placed on either the dog's fore- or hind limb and connected to an OBPM. Systolic, diastolic, and mean arterial blood pressures (SAP, DAP, and MAP, respectively) were recorded from both arteries and the OBPM every 5 minutes for 30 minutes (baseline), during a 30-minute period in which dogs received a phenylephrine infusion IV to induce hypertension, and for 30 minutes after discontinuation of the infusion. Mean differences in blood pressure values and confidence intervals were calculated to compare the indirect and direct measurement techniques. RESULTS: In dogs, oscillometry underestimated SAP during normotension, and the difference between oscillometric and direct measurements increased during hypertension. Oscillometry underestimated DAP, but the difference between oscillometric and direct measurements decreased during hypertension. There was close agreement among techniques for MAP determinations. Biases between direct measurements and OPBM blood pressure values measured from dogs' forelimbs or hind limbs were not significantly different. CONCLUSIONS AND CLINICAL RELEVANCE: In normotensive dogs, oscillometric measurements of MAP and SAP agreed more closely with direct arterial pressure measurements than oscillometric estimates of DAP. Oscillometric measurement of MAP was accurate during both normotension and hypertension in dogs.

Animals↗
PubMedDate not supplied

A modified technique for tail cuff pressure measurement in unrestrained conscious rats.

In physiological experiments, it is essential to measure arterial pressure (AP) and heart rate (HR) in animals. Tail cuff pressure (TCP) measurement using photoelectric volume oscillometry has been commonly used. We designed a new technique for continuous measurement of AP and HR in conscious, unrestrained rats. This is based on the observation that fixation of the rat's tail with tape keeps the animal in position without struggling. The animal is free to move its body. To test the accuracy of this new technique, Sprague-Dawley rats underwent four AP and HR measurement techniques. These included a new unrestrained method (UR), which was compared to the following three methods: traditional restrained TCP method with restrainer, direct monitoring of AP and HR with femoral artery catheterization and a combination of photoelectric volume oscillometry (with body heating to 37 degrees C) and femoral arterial recording. The results show that the modified UR measurement provides accurate data on AP and HR. This method obtains a lower value of HR and similar mean AP when compared to direct monitoring from femoral arterial catheterization. Accordingly, the modified unrestrained TCP measurement can be used in conscious rats as a noninvasive method.

Animals↗
PubMed1999

[Anesthesia in geriatric patients. The determination of physiological variables for cognitive function in geriatric patients after regional or general anesthesia].

OBJECTIVE: The aim of the present study was to show the influence of the parameters of gas exchange (arterial oxygen pressure paO2, arterial oxygen saturation SatO2) and haemodynamics (arterial systolic and mean blood pressure RRs and MAP) on the restitution of cognitive functions in geriatric patients scheduled for elective hip arthroplasty. METHODS: A total of 30 patients (70 years, ASA II) were randomized to be operated either in regional anaesthesia (n = 15) or general anaesthesia (n = 15). PaO2 (by capillary blood gas analysis), RRs and MAP (by oscillometry) were measured 15 and 90 minutes after arrival in the recovery unit (t1 and t2), 24 and 72 hours postoperatively (t3 and t4), and cognitive functions were tested. Intraoperatively, throughout the day and the first night after surgery we measured satO2 by continuous pulse oximetry. We recorded MAP and RRs by oscillometry every 3 minutes during the operation and every 15 minutes for the rest of that day and night. RESULTS: The parameters of gas exchange and haemodynamics did not differ among the groups. PaO2 was significantly reduced in both groups compared to baseline 24 hours postoperatively (t3) and remained low until 72 hours postoperatively (t4). Nearly all cognitive functions were significantly reduced in both groups compared to baseline 15 and 90 minutes after arrival in the recovery unit (t1 and t2), but recovered on the first postoperative day (t3). Both groups kept deficits in verbal memory and reading capacity up to the third postoperative day (t4). There was no correlation between the physiological parameters and the restitution of the tested cognitive functions. CONCLUSION: The restitution of cognitive functions during the first three postoperative days in geriatric patients scheduled for elective hip surgery does not depend on the anaesthetic technique. According to our results regional anaesthesia does not show any advantage for geriatric patients undergoing elective hip arthroplasty.

Aged↗