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PubMed2000

Use of residual fraction instead of residual volume in the evaluation of lower urinary tract symptoms.

Assessment of postvoid residual volume (PVR) has become a valuable routine investigation in the evaluation of bladder outlet obstruction. PVR has been shown to have interindividual and intraindividual variation and dependence on prevoid urinary volume, thus raising a question about its significance. The aim of this study was to investigate an alternate parameter more reliable than PVR, described as residual fraction (RF) and calculated as (PVR x 100)/prevoid volume. Ninety-three adult patients with lower urinary tract symptoms (LUTS) presenting to the urology outpatient clinic were evaluated for bladder outlet obstruction. Patients with urinary retention and neurological disorders were excluded. Evaluation was by clinical assessment, uroflowmetry, and ultrasound bladder for prevoid and postvoid urine volume estimation. The latter was compared with RF. Results were statistically analyzed using bivariate analysis and Spearman's test. In 93 evaluable patients, there were 87 (94%) males and 6 (6%) females. Residual volume ranged from 4 to 450 mL (mean 91.4+/-92.7 mL). Peak flow rate (Qmax) varied from 3 to 49 mL/s (mean 9+/-15 mLis). Two-tailed correlation between PVR and Qmax was significant at the .05 level, whereas a more significant R value at .01 was observed between RF and Qmax. There was a strong positive correlation between RF and PVR with Qmax. RF statistically correlated better with Qmax than PVR. It is recommended that RF be used instead of PVR in the routine noninvasive evaluation of LUTS.

Adult↗
PubMed2004

Continuous nasogastric tube feeding: monitoring by combined use of refractometry and traditional gastric residual volumes.

BACKGROUND & AIMS: Traditional use of gastric residual volumes (GRVs) is insensitive and cannot distinguish retained enteral formula from the large volume of endogenous secretions. We designed this prospective study to determine whether refractometry and Brix value (BV) measurements could be used to monitor gastric emptying and tolerance in patients receiving continuous enteral feeding. METHODS: Thirty-six patients on continuous nasogastric tube feeding were divided into two groups; patients with lower GRVs (<75 ml) in Group 1, patients with higher GRVs (>75 ml) in Group 2. Upon entry, all gastric contents were aspirated, the volume was recorded (Asp GRV), BV measurements were made by refractometry, and then the contents were reinstilled but diluted with 30 ml additional water. Finally, a small amount was reaspirated and repeat BV measurements were made. Three hours later, the entire procedure was repeated a second time. The BV ratio, calculated (Cal) GRV, and volume of formula remaining were calculated by derived equations. RESULTS: Mean BV ratios were significantly higher for those patients in Group 2 compared to those in Group 1. All but one of the 22 patients (95%) in Group 1 had a volume of formula remaining in the stomach estimated on both measurements to be less than the hourly infusion rate (all these patients had BV ratios <70%). In contrast, six of the 14 patients in Group 2 (43%) on both measurements were estimated to have volumes of formula remaining that were greater than the hourly infusion rate (all these patients had BV ratios >70%). Three of the Group 2 patients (21%) whose initial measurement showed evidence for retention of formula, improved on repeat follow-up measurement assuring adequate gastric emptying. The remaining five patients from Group 2 (35%) had a volume of formula remaining that was less than the hourly infusion rate on both measurements. The pattern of Asp GRVs and serial pre- and post-dilution BVs failed to differentiate these patients in Group 2 with potential emptying problems from those with sufficient gastric emptying. CONCLUSIONS: Refractometry and measurement of the BV may improve the clinical utilization of GRVs, by its ability to identify the component of formula within gastric contents and track changes in that component related to gastric emptying.

Enteral Nutrition↗
PubMed1985

The effect of methacholine inhalation challenge on regional residual volume in patients with subclinical asthma.

Regional residual volume to total lung capacity (RVr/TLCr) was measured with xenon 133 before and after methacholine challenge in 26 nonsmoking subjects (mean age 34 years). Eleven were normal control subjects and 15 were patients referred for methacholine challenge because of previous asthma-like symptoms. All had normal pulmonary function and normal RVr/TLCr distribution. Following methacholine challenge, RVr/TLCr increased in two control subjects and ten patients who also had decreases in FEV1 of greater than 20 percent. The RVr/TLCr changes were patchy, suggesting that the degree of bronchospasm varied between individual lung regions. The other 14 subjects did not have a 20 percent decrease in FEV1, but two controls and four patients had generalized increases in RVr/TLCr, while seven controls and one patient had no significant changes in RVr/TLCr. In all subjects, FEV1 and RVr/TLCr returned to the baseline level after salbutamol administration. The results indicate that methacholine can cause localized or diffuse effects on lung emptying and that bronchodilator completely reverses the bronchoconstriction induced by methacholine.

Adult↗
PubMed1977

Increased pulmonary residual volume in patients with hyperlipoproteinemias.

A syndrome, characterized by pulmonary hyperdistension (increased residual volume, closing capacity and Motley index), was observed in patients with hyperlipoproteinemias without without other known causes of pulmonary disease. This syndrome is mostly asymptomatic;hyperdistension is of variable degree and not directly correlated to plasma lipid levels. It is partially reversible after reduction of lipidemia. The cause of this syndrome is not known. It may explain a decreased pulmonary working capacity in asymptomatic hyperlipidemic patients.

Adult↗
PubMed1987

Clinical significance of an isolated reduction in residual volume.

To determine the significance of an isolated reduction in residual volume (RV), the medical records and chest radiographs of 69 patients who had a RV less than or equal to 65% of predicted and normal VC, DLCO, and expiratory flow rates were reviewed. Sixty-three of 69 patients (92%) had clinical conditions that could account for their decreased RV. Definite disease was considered to be present in the 39 patients with radiographically apparent parenchymal (n = 18) or chest wall (n = 21) abnormalities, whereas 24 others with clinical diagnoses such as congestive heart failure or toxic inhalation were considered to have probable disease. All patients who had a RV below 50% of predicted had either definite or probable disease. Follow-up testing of 19 patients 31 +/- 21 months after their initial reduction in RV was first documented indicated that the RV accurately reflected the patient's current clinical status in that it increased by 17 +/- 16% of predicted in those who were clinically improved and decreased by 27 +/- 7% in those who were clinically worse. In patients who were clinically stable, the isolated reduction in RV was a persistent finding. We conclude that an isolated reduction in RV is a clinically significant finding indicative of pulmonary or chest wall disease. Interval changes in RV reflect alterations in disease activity.

Female↗
PubMed1981

Effects of smoking on regional residual volume in young adults.

Tests of overall lung function often reveal abnormalities in elderly smokers, but lung function is less consistently deranged in young smokers. Since airway closure at higher than normal lung volumes is thought to be an early indicator of lung dysfunction in asymptomatic smokers, we used 133xenon to measure regional residual volume, which is affected by airway patency, with the expectation that any abnormalities present in young smokers may be more apparent if searched for on a regional basis. We found no significant difference in overall lung function between 11 nonsmokers and 20 smokers (mean age=23.8 years), but residual volume was significantly higher in the lower-lung regions of the smokers. The results indicate that even in young persons the lungs are functionally disturbed by smoking, and the pattern of abnormality is similar to that seen in patients with chronic obstructive lung disease.

Adult↗
PubMed2000

Is a reduction in residual volume a sub-clinical manifestation of hydrogen sulfide intoxication?

BACKGROUND: A number of employees at an aircraft factory were accidentally exposed to hydrogen sulfide. Because of concern that this may have resulted in lung injury, forty-seven workers were referred for clinical and physiological evaluation. METHODS: Comprehensive pulmonary function tests were performed including spirometry, flow volume curves, static lung volumes, and diffusion capacity for carbon monoxide. RESULTS: The results obtained indicated that ten people (23%) had an isolated reduction in residual volume. This was an unexpected finding as other physiological indices of lung function were within normal limits. Clinical examination was also normal, therefore, radiological investigations were considered inappropriate. CONCLUSIONS: It is suggested that the decrement in residual volume, in the presence of other normal indices of lung function, could represent a sub-acute manifestation of hydrogen sulfide intoxication.

Aircraft↗
PubMed1998

Respiratory physiology teaching: determination of residual volume by applying the indicator-dilution technique.

Apart from the current teaching of spirometric methods in laboratory courses on respiratory physiology, we have included an experiment in which medical students determine their own residual volume by applying the indicator-dilution technique. For hygienic reasons we used a bag-in-the-box system to dilute helium within alveolar space by performing the single-breath method. Although each participant independently underwent only one single-breath maneuver, we gained a reliable relationship between residual volume and subjects' height and body weight in 68 female (r = 0.6, P < 0.0001) and 99 male (r = 0.42, P < 0.0001) students. From this successful outcome and with the opportunity to discuss the limitations of the single-breath method as well, we inferred that this experiment affords a transparent and instructive approach to interpreting the determination of lung volumes on the basis of the indicator-dilution technique.

Adult↗
PubMed1982

Regional distribution of ventilation at residual volume in induced bronchospasm.

The regional distribution of a bolus of gas inhaled at residual volume (RV) is attributed to regional airway closure and is responsible for the phase IV of the single-breath washout during the following deflation. As bronchospasm increases the range of airway opening pressures through the lung, the regional distribution of the bolus could change with effects on the shape of the single-breath washout. We investigated the regional distribution of boluses inhaled at RV and their single-breath washouts during methacholine-induced bronchospasm in prone dogs. With increasing total lung resistance (RL) we first observed in five out of eight animals a preferential "redistribution" of the bolus to the upper caudal regions of the lung, which could be partially attributed to the increased lung volume at RV. When maximal RL was attained, the bolus was evenly distributed through all regions of the lung in these animals with disappearance of phase IV and increased slope of phase III, and a final decrease of tracer concentration at low lung volumes was observed. We conclude from these data that increased bronchomotor tone in dogs results in a less homogeneous intraregional distribution of the bolus with increased slope of phase III and in a more even interregional distribution leading to disappearance of phase IV. In severe bronchospasm the downward slope at low lung volume suggests intraregional closed lung units emptying through collateral pathways into still open neighboring units.

Animals↗
PubMed1984

Factors determining residual volume in normal and asthmatic subjects.

We have studied the mechanisms determining the residual volume (RV), by inducing temporary changes in RV through respiratory manoeuvres and bronchodilation. Four asthmatic and 5 normal subjects inhaled placebo, salbutamol, and ipratropium bromide, and performed maximum expiratory manoeuvres after partial and maximal inspiration. RV and static lung pressure-volume measurements were made in each experiment. After bronchodilation, RV increased in both groups after a maximal inspiration, while bronchodilatation, as such, decreased RV in both groups. We also found unexpectedly that in the asthmatic patients, the static transpulmonary pressure (Pst) at low lung volumes increased after bronchodilatation. Our findings can be explained if bronchodilators open-up closed airways, and if a preceding maximal inspiration decreases the elastic recoil pressure of the lungs causing a change of the lung volume at which airway closure occurs. The results also support that Pst at low lung volume is influenced by airway closure and underestimates the elastic recoil pressure of the lungs, even in normal subjects. We postulate that the increase in Pst at low lung volumes after bronchodilatation is due to smaller amounts of trapped gas.

Adult↗
PubMed1996

Postvoid residual volume cannot be accurately estimated by bimanual examination.

This study aimed to test the recommendation in the Agency for Health Care Policy and Research Practice Guideline on urinary incontinence that postvoid residual volume PVR estimates can be done by palpation. Postvoid residual volumes were obtained on 50 consecutive women presenting for evaluation of incontinence. Volumes were first estimated by bimanual examination and were then immediately measured by catheterization. Of 7 women who had a positive PVR, defined as greater than 50 ml, only 1 was estimated at greater than 50 ml on bimanual examination. The sensitivity of bimanual examination compared to catheterization to detect a positive PVR was 14%; specificity was 67%. Based on this assessment, the AHCPR guideline's inclusion of palpation estimates of PVR cannot be endorsed, unless a given practitioner has repeated a similar type of evaluation in his or her practice to determine whether the sensitivity is higher than that found in this study.

Adult↗
PubMed2004

Enhancing interpretation of gastric residual volume by refractometry.

The traditional practice of gastric residual volumes (GRVs) is flawed in its design and conception, is poorly standardized in its technique, is an inaccurate measure of gastric emptying, and serves as an insensitive marker for regurgitation and aspiration. The refractive index of a solution (like an enteral formula) is a physical property of that solution, which is remarkably constant and reproducible under varying conditions of concentration, pH, and temperature. Refractometry may be performed quickly and easily at the bedside, requires only a small representative sample of aspirated solution, and provides valuable measurements that can be used to calculate both the true total volume of contents and the specific volume of formula remaining in the stomach. Refractometry complements the use of GRVs as a monitor for patients receiving enteral feeding and should improve the accuracy with which patients at risk for aspiration may be identified.

Journal Article↗
PubMed1985

Accuracy of residual volume prediction--effects on body composition estimation in pulmonary dysfunction.

The accuracy of predicting residual volume (RV) and the effect of employing such predictions in the assessment of body composition by hydrostatic weighing was examined. Prediction equations derived by Wilmore (Med. Sci. Sports, 1969) and Boren et al. (Am. J. Med., 1966) were cross-validated on 400 male subjects with varying degrees of pulmonary dysfunction. Statistical analysis included comparison of predicted vs measured RV and regression analysis of measured on predicted values. Neither equation met acceptable statistical criteria (p greater than .05). Underwater weights were calculated based upon the measured RV and an assumed standard body weight, body density, and percent body fat (i.e., 70 kg, 1.0647 g/cc and 15.0%). Predicted RV was then substituted in the calculation and the effect on standardized values examined, between the calculated and standardized percent fat value with both equations. Results suggest in the present subjects, RV cannot be accurately predicted and the use of such prediction equations introduces sizable errors in body composition estimation.

Adult↗
PubMed1987

Comparison of a radionuclide method and catheterization for the measurement of residual volume of urine in the bladder.

Residual urine volume in the bladder was measured using a gamma camera and Tc-99m DTPA labeling of the urine and was compared to urethral catheterization in 21 male patients. The results of the radionuclide method did not differ significantly from the catheterization (P less than 0.001) and a good correlation was found between the two methods (r = 0.98). The results suggest that the simple, safe radionuclide method may be used instead of catheterization to measure residual urine volume in the bladder.

Adult↗
PubMed1989

Effects of oral cimetidine and ranitidine on gastric pH and residual volume in children.

The effect of orally administered cimetidine 7.5 mg/kg (group 1), ranitidine 1.5 mg/kg (group 2), ranitidine 2.0 mg/kg (group 3), or a placebo (group 4) on gastric pH and gastric residual volume of 60 healthy children 2-6 yr of age admitted for elective surgery was evaluated. Both cimetidine and ranitidine administered 1-2 h prior to induction of anesthesia effectively increased the gastric pH:5,47 - 1.85 ml/kg (group 1), 4.92 +/- 2.1 ml/kg (group 2), 5.30 +/- 1.82 ml/kg (group 3) compared with 1.75 +/- 0.58 ml/kg (group 4) (P less than 0.001). A single dose of ranitidine 1.5 mg/kg was an effective as ranitidine 2.0 mg/kg and cimetidine 7.5 mg/kg. Neither drug decreased the gastric residual volume: 0.32 +/- 0.33 ml/kg (group 1), 0.31 +/- 0.06 ml/kg (group 2), 0.23 +/- 0.05 ml/kg (group 3), and 0.33 +/- 0.05 ml/kg (group 4). The combination of a volume greater than 0.4 ml/kg and a pH less than 2.5 was found in 33% (five of 15) of patients in the placebo group (group 4). In contrast, there were no patients with this combination in groups 1, 2, or 3 (P less than 0.001).

Administration, Oral↗
PubMed1992

Residual volume in a general population. Effects of body size, age, cigarette smoking, and respiratory symptoms.

Residual volume (RV) was obtained by subtracting vital capacity from total lung capacity determined by the single breath helium dilution (TLCsb) to measure CO diffusing capacity in 2,680 subjects (8 to 64 years old) of a general population sample. There were 712 normal subjects (243 male and 469 female subjects) selected to evaluate the pattern of RV by age and to derive reference values for internal comparisons. From 8 to 20 years old, RV showed an increase because of the cross-sectional body size effect; after 20 to 30 years, RV was still increasing, however, at a lower level. Age and height coefficients were significantly related to RV in younger and older ages, both in male and female subjects. The RV percent predicted and RV/TLC percent were higher in smokers when compared to nonsmokers and exsmokers (the difference was significant in male subjects). A dose-response effect was observed between RV percent predicted, RV/TLC percent, and pack-years. The RV percent predicted and RV/TLC percent were significantly higher in smokers and nonsmokers with FEV1 percent predicted below the normal limit (the difference was significant in male subjects). Moreover, higher values of RV percent predicted and RV/TLC percent were observed in subjects with wheezy symptoms in male smokers and nonsmokers. A negative significant correlation was observed between RV/TLC percent and the diffusing capacity adjusted for lung volume (DL/VA) in smokers, exsmokers and nonsmokers of both sexes, confirming the hypothesis that the decrease in DL/VA may be ascribed to the enlargement of terminal air spaces. In conclusion, determination of RV by the single breath helium dilution method is suitable in epidemiology, and it allows additional important information for understanding the physiopathologic mechanisms related to the pathogenesis of chronic obstructive lung disease.

Adolescent↗
PubMed1982

Contribution of residual volume to the increased alveolar plateau with bronchoconstriction.

We studied 10 normal volunteers with single-breath nitrogen tests before and after methacholine-induced bronchoconstriction. On the first day we challenged each subject with increasing methacholine concentrations to obtain a 20% drop in the partial forced expired volume in 1 s/partial forced vital capacity ratio. This resulted in an increased residual volume (RV) from 1,536 +/- 138 to 2,371 +/- 216 ml (mean +/- SEM, p less than 0.01). On the following day we did single-breath nitrogen tests from RV, RV + delta V (delta V is the individual's RV increase after bronchoprovocation) and after a similar methacholine rechallenge. Baseline slope of phase III was 0.88 +/- 0.11% N2/1 (mean +/- SEM), 1.36 +/- 0.22% N2/1 with the RV + delta V test (p less than 0.01), and 2.84 +/- 0.68% N2/1 with bronchoconstriction (p less than 0.05). The results show that the changes in RV per se accounted for 24% of the increase in the slope of phase III seen with bronchoprovocation.

Adult↗
PubMed2004

Unreliable residual volume measurement after increased water load diuresis.

BACKGROUND: The aim of the present study was to examine whether increased water load intake prior to ultrasound examination of the lower urinary tract, affects the measurement of postvoid residual urine volume. PATIENTS AND METHODS: Ninety four male patients with postvoid residual volumes after increased water load diuresis of more than 100 mL (PVR1) were included in the present study. All patients underwent a second PVR measurement by an urologist with a portable transabdominal bladder ultrasound scan without having received an increased water load (PVR2). A comparison of the measurements was performed and the PVR values were also correlated with other parameters, such as age, International Prostate Symptom Score, prostate volume and serum prostate-specific antigen (PSA) values. RESULTS: Postvoid residual urine volume after increased water load diuresis (PVR1) differed from that recorded after normal bladder filling and voiding at first desire (PVR2), with the former being larger than the later in every patient (P < 0.001). The PVR values, PVR1 and PVR2, were independent to patient age, symptom score prostate volume and PSA value. CONCLUSIONS: Measurement of postvoid residual volume in a relaxed patient, who voids at first desire, represents everyday life and should be the correct method of testing.

Adult↗