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PubMed2004

Vital capacity manoeuvre in general anaesthesia: useful or useless?

As atelectasis occurs in most patients during general anaesthesia and may be one of the major causes for the development of hypoxaemia and nosocomial pneumonia, its prevention may be considered as an important objective in perioperative management. The major causative mechanisms are the loss of respiratory muscle tone, compression and gas absorption. Vital capacity manoeuvres have been proposed as a means to eliminate atelectasis in the vast majority of patients and restore normal pulmonary gas exchange during general anaesthesia. In this review we describe the pathogenesis of atelectasis in the perioperative period and discuss in the light of recent published investigations the suitability of the vital capacity manoeuvre as a tool during general anaesthesia. Reviewing the current literature, a vital capacity manoeuvre during general anaesthesia may only be useful under specific circumstances when mechanical ventilation with a high inspiratory fraction of oxygen is required or during cardiac surgery at the end of cardiopulmonary bypass to reduce the amount of atelectasis and to maintain adequate gas exchange.

Anesthesia, General↗

PubMed1975

Essay of any ventilators by means of a pulmonary model with adjustable resistance, compliance and vital capacity.

After a critical study of classic lung models, showing that linear resistances are not faithful nor justified and that pneumotachograph is not a good measuring apparatus because of its inaccuracy (it changes calibration according to the nature of gas mixture and needs integration to determine volumes), authors present their own lung "model". In this model, it is possible to adjust resistance, compliance, vital capacity and residual volume. Parabolic resistances are used, because they more approach physiologic ones. Building of resistances (diaphragms), compliances (rigid tanks with adjustable elements), vital capacity (elastic membrane between two grills) is simple to realise and easy to reproduce. Measures of pressure and volume are given directly by gauges and are insensitive to gas nature, which is important in respiratory physiology. Flow-rates are deducted from volume values. The lung model can be used in a twin-cell shape to show the effects of artificial ventilation in case of pulmonary asymmetry. Examples given underline the interest of having a model with resistances easy to build and an adjustable vital capacity.

Airway Resistance↗

PubMed2003

Bispectral monitoring during vital capacity rapid inhalation induction with sevoflurane.

STUDY OBJECTIVE: To evaluate the variables of bispectral index (BIS) values during vital capacity rapid inhalation induction (VCRII) with sevoflurane. DESIGN: Randomized, prospective study. SETTING: University hospital. PATIENTS: 40 ASA physical status I and II patients scheduled for elective orthopedic surgery with general anesthesia. INTERVENTIONS: Patients was divided into two groups, both of which received intravenous (IV) injection of propofol 2 mg/kg followed by inhalation of sevoflurane 3% (Group P), or vital capacity inhalation induction with sevoflurane 8% (Group S). After loss of consciousness, tracheal intubation was performed with vecuronium 0.1 mg/kg. MEASUREMENTS AND MAIN RESULTS: The induction times in Group P were significantly shorter than those in Group S (p < 0.01). In Group S, BIS values were gradually decreased and maintained the adequate hypnotic levels were maintained during induction. In Group P, although BIS values were rapidly decreased, the values remained higher compared with Group S. The BIS value before intubation in Group S was significantly lower than that in Group P (25 +/- 9 and 38 +/- 7, respectively; p < 0.01). Five of 20 Group P patients had BIS values exceeding 60 before tracheal intubation, but no patient in Group S had a BIS value as high. Mean arterial pressure immediately after intubation in Group S was significantly lower than that in Group P (p < 0.05). CONCLUSION: VCRII with a high concentration of sevoflurane provided adequate BIS values during induction, suggesting that it may allow smoother transition from anesthesia induction to maintenance, and also maintain an adequate hypnotic level in readiness for certain stimuli such as laryngoscopy and tracheal intubation.

Adult↗

PubMed1990

Peak inspiratory flow and inspiratory vital capacity of patients with asthma measured with and without a new dry-powder inhaler device (Turbuhaler).

In 101 asthmatic adults with varying degrees of bronchial obstruction, lung function tests including peak inspiratory flow (PIF), inspiratory vital capacity (IVC), peak expiratory flow (PEF), forced vital capacity (FVC), and forced expiratory volume in one second (FEV1) measurements were made. Significant correlations between inspiratory and expiratory volumes were found. In most patients, PIF was less reduced than the expiratory parameters of pulmonary function. When inhalation was performed through the new multi-dose, dry-powder inhalation device, Turbuhaler (PIF-TBH), it was significantly lower than PIF measured without Turbuhaler. In previous studies, PIF-TBH of 30 l.min-1 or more has proven sufficient to produce a therapeutic dose of terbutaline, and to produce significant bronchodilatation. Of 101 asthmatics in the present study, only four had PIF-TBH of less than 30 l.min-1. Although no parameters of spirometry could accurately predict PIF-TBH, there was a tendency for patients with severely impaired ventilatory capacity to produce lower PIF-TBH than patients with normal or near-normal ventilatory capacity. If patients with severely impaired ventilatory capacity are to receive inhalation therapy through Turbuhaler, either PIF or PIF-TBH should be measured, or the effect should be carefully monitored.

Adult↗

PubMed1977

Serial measurement of vital capacity in patients on chronic haemodialysis.

Serial measurements of vital capacity (VC) were performed on nine patients on chronic haemodialysis. In six patients the VC remained stable, they were all adequately dialysed and working full-time. Reduction of dialysis time in one of these patients brought about a gradual onset of left heart failure which was preceeded by a decline of VC. In the three remaining patients a decrease of VC preceeded the onset of heart failure, and a rise of VC values signified improvement of cardiac performance. Serial recordings of VC are recommended as a useful objective guide to evaluation and treatment of patients on haemodialysis.

Adult↗

PubMed1986

Effect of posture on vital capacity.

The influence of some extreme body postures on vital capacity (VC) was examined in young adult humans. Two postures required full support of body weight by the arms: arms up, hanging from a bar, and arms down with hands gripping parallel bars. Three involved muscles that flex and extend the trunk: a partial sit-up position while supine and nearly maximal spinal extension and flexion while standing. Changes at the inspiratory and expiratory volume extremes were recognized by having the subjects do two VC efforts: the first standing and the second in the posture in question while continuing to breathe on the spirometer. Control observations in which the second of a VC pair was performed in an unstressed posture allowed correction for the influence of rebreathing. The changes in corrected VC were small, the greatest being an average reduction of approximately 8% in the partial sit-up position. During full support of body weight by the arms, the VC was slightly increased due to a significant increase in the inspiratory extreme and no change in the expiratory extreme. Spinal extension produced small increases in lung volume at both extremes with no significant change in VC, whereas spinal flexion did not influence the upper extreme but did increase lung volume at the lower extreme. The changes are discussed in terms of trunk muscle action.

Adolescent↗

PubMed2002

Gastrostomy insertion in ALS patients with low vital capacity: respiratory support and survival.

The authors evaluated their uncontrolled, retrospective experience with 33 patients with ALS with erect or supine forced vital capacity less than 50% predicted who underwent attempted percutaneous endoscopic gastrostomy (PEG) tube placement using noninvasive positive pressure ventilation and oxygen support and conscious sedation anesthesia. Gastrostomy tubes were successfully placed in all patients. Mean survival was 211 days with most patients (67%) surviving more than 180 days. Forced vital capacity at the time of PEG placement did not predict survival.

Amyotrophic Lateral Sclerosis↗

PubMed2006

Vital capacity as a predictor of outcome in elderly patients with rib fractures.

BACKGROUND: This study tests the relationships between early bedside vital capacity (VC) measurement and morbidity, mortality, and resource consumption in geriatric blunt chest trauma patients with rib fractures. METHODS: This was a retrospective study examining all patients > or = 65 years old with rib fractures who had a VC measured within 48 hours of their emergency department evaluation. Outcome variables included pulmonary complications, death from pulmonary complications, hospital length of stay (LOS), intensive care unit length of stay (ICU LOS), and discharge disposition. RESULTS: Thirty-eight patients met the study criteria. The mean age was 80.2 (+/-7.4) years, the mean number of rib fractures was 3.6 (+/-1.6), and the mean ISS was 6.9 (+/-4.7). VC and the percentage of the predicted vital capacity (pVC) were both inversely correlated with LOS (p = 0.0076 and p = 0.0172, respectively). Linear regression analysis suggested that patients with a VC < 1.4 L or < 55% of their pVC had a LOS > 3 days. Mean VC was 36% higher in patients who were discharged home versus those discharged to an extended care facility (ECF; p = 0.025). There was a trend toward significance when comparing VC to ICU LOS (p = 0.079), but none in predicting pulmonary complications (p = 0.3299). No correlations between VC and mortality can be drawn given the single death in the cohort. CONCLUSIONS: Bedside VC is a simple measurement which could predict LOS in elderly patients with rib fractures and may identify those patients requiring ECF upon discharge. Further prospective study may highlight the utility of emergency room VC in determining the disposition of these patients.

Aged↗

PubMed1980

Calibration of time derivatives of forced vital capacity by explosive decompression.

A simple, portable, inexpensive device is described that simulates expiratory flow curves for calibration of spirometers. A 4-L metal cylinder filled with copper mesh is fitted with a precision manometer. The pressure is increased to twice atmospheric and released by explosive decompression through 4 easily interchangeable resistors. The ratio of forced expiratory volume in one second to forced vital capacity ranged from 0.80 to 0.25, thus encompassing the range from normal to severe obstruction. Accuracy was defined by 25 measurements of forced vital capacity that differed by no more than 0.5% from the actual cylinder volume. Repeatability was reflected by a standard deviation of at most 0.04 L/s for one-second forced expiratory volume, mid-expiratory flow, and instantaneous flows at 50 and 25% of the forced vital capacity. Peak flow was less reproducible. Calibrations of a water spirometer at increased altitude and at temperatures from 4 degrees to 37 degrees C revealed no significant changes in volume or flow rates. Standard values have remained unchanged for 2.5 yr. Three volume spirometers and 2 primary flow devices were tested extensively.

Altitude↗

PubMed2006

Should forced expiratory volume in six seconds replace forced vital capacity to detect airway obstruction?

It has been suggested that forced expiratory volume in six seconds (FEV(6)) should be substituted for forced vital capacity (FVC) to measure fractions of timed expired volume for airflow obstruction detection. The present authors hypothesised that this recommendation might be questionable because flow after 6 s of forced expiration from more diseased lung units with the longest time constants was most meaningful and should not be ignored. Furthermore, previous studies comparing FEV(6) and FVC included few subjects with mild or no disease. The present study used spirometric data from the USA Third National Health and Nutrition Evaluation Survey with prior published ethnicity- and sex-specific equations for FEV(1)/FEV(6), FEV(1)/FVC and FEV(3)/FVC, and new equations for FEV(3)/FEV(6), all derived from approximately 4,000 adult never-smokers aged 20-80 yrs. At 95% confidence intervals, 21.3% of 3,515 smokers and 41.3% of smokers aged >51 yrs had airway obstruction; when comparing FEV(1)/FEV(6) with FEV(1)/FVC, 13.5% were concurrently abnormal, 1.5% were false positives and 4.1% were false negatives; and when comparing FEV(3)/FEV(6) with FEV(3)/FVC, 11.6% were concurrently abnormal, 3.3% were false positives and 5.7% were false negatives. Substituting forced expiratory volume in six seconds for forced vital capacity to determine the fractional rates of exhaled volumes reduces the sensitivity of spirometry to detect airflow obstruction, especially in older individuals and those with lesser obstruction.

Adult↗

PubMed1987

[Vital capacity restitution curve: prognostic value in chronic decompensated respiratory insufficiency].

From a series of 50 patients with acute decompensation of chronic obstructive lung disease (38 of whom were treated by mechanical ventilation), the authors demonstrate the prognostic value of an easily obtained parameter of respiratory function: the vital capacity restitution curve (VCRC). From daily measurements of vital capacity, beginning on the day of admission, a graph is constructed which shows an initial period of increase in the degree of restitution, followed by stabilization of the values. An analysis of the various parameters embodied in this graph provides information about the prognosis. Such graphs can be divided into 3 zones of prognostic value: a favourable zone, an intermediate zone (mediocre survival with or without mechanical ventilation) and an unfavourable zone (death during the acute phase). Although a favourable prognosis can be made after 4 days of observation and almost always by the 10th day, an unfavourable prognosis cannot be made before the 21st day.

Aged↗

PubMed1998

Repeated vital capacity manoeuvres after cardiopulmonary bypass: effects on lung function in a pig model.

Respiratory failure following cardiopulmonary bypass (CPB) is a major complication after cardiac surgery. A vital capacity inflation of the lungs, performed before the end of CPB, may improve gas exchange, but the necessity to repeat it is unclear. Therefore, we studied 18 pigs undergoing hypothermic CPB. A vital capacity manoeuvre (VCM) was performed in two groups and consisted of inflating the lungs for 15 s to 40 cm H2O at the end of CPB. In one group, VCM was repeated every hour. The third group served as controls. Atelectasis was studied by CT scan. Intrapulmonary shunt increased after bypass in the controls and improved spontaneously 3 h later without returning to baseline values. From 3 to 6 h after CPB, there was no more improvement and more than 10% atelectasis remained at 6 h. In contrast, the two groups treated before termination of CPB with VCM showed only minor atelectasis and no abnormal changes in gas exchange directly after bypass or later. We conclude that the protective effect of VCM remained for 6 h after bypass, and there was no extra benefit on gas exchange by repeating the VCM.

Animals↗

PubMed2005

Vital capacity and patient controlled sevoflurane inhalation result in similar induction characteristics.

PURPOSE: To compare patient controlled inhalational induction (PCI) with the most commonly used sevoflurane induction technique, vital capacity inhalational induction (VCI). METHODS: Following approval of the Research Ethics Board, 124 outpatients undergoing knee arthroscopy were randomly assigned to receive either PCI or VCI sevoflurane followed by laryngeal mask airway (LMA) insertion and sevoflurane maintenance. In the PCI group, the circle circuit was not primed. The patients were asked to hold the facemask themselves and breathe normally with sevoflurane 8% in oxygen at a flow rate of 4 L x min(-1). In the VCI group, the circle circuit was primed and patients were asked to take vital capacity breaths with sevoflurane 8% at an oxygen flow rate of 8 L x min(-1). The LMA was inserted as soon as the patient's jaw was relaxed. Time from induction to LMA insertion was recorded and insertion conditions rated. The amount of sevoflurane used for LMA insertion was calculated. Vital signs were monitored at one-minute intervals until ten minutes after LMA insertion. RESULTS: Demographic data were comparable. There were no differences with respect to LMA insertion time (PCI - 3.4 min vs VCI - 3.3 min), laryngospasm (PCI - 7% vs VCI - 5%), mean arterial pressure, heart rate, SaO(2) as well as patient's overall satisfaction. CONCLUSION: PCI was comparable to VCI in sevoflurane induction with respect to the speed of induction, side effects during induction and patient satisfaction. However, PCI requires no special training and is widely applicable to all patient populations.

Adult↗

PubMed1992

Some observations on the variation in height coefficients in prediction equations for forced vital capacity.

Intercept and height coefficients in prediction equations for forced vital capacity (FVC) are highly correlated and highly variable, due in part to the small coefficient of variation of height (4%). This degree of imprecision and relationship was observed among the coefficients of a set of 26 unrelated published prediction equations, and appeared to dominate any systematic differences between them in methodology and technique. The findings indicate that care needs to be taken when using equations for predicting the FVC of people at the extremes of height. They also demonstrate the need for careful planning in the design of studies intended for the compilation of prediction equations, including provision for sufficient numbers of observations. Support is also given to the use of a composite formula based on the averaging of many individual prediction equations. The results are applicable to other similar and commonly used lung function equations (e.g. that for forced expiratory volume in 1 second, FEV1) that employ height as a predictor variable.

Adult↗

PubMed1979

The timing of the forced vital capacity.

Based on analysis of more than 2,500 forced vital capacity (FVC) maneuvers, we examined 2 aspects of the standards for spirometry recommended by the 1977 Snowbird Workshop concerning the timing of the FVC maneuver. We compared the forced expiratory volume in one sec (FEV1) when timing was initiated by the back extrapolation method with FEV1 when timing was initiated by flow or volume threshold to determine whether the latter offered a reliable equivalent. Although the mean differences appear to be relatively small, because of variability in initiating expiratory effort, neither alternative is likely to offer a uniformly accurate numeric equivalent to backward extrapolation. We also measured the volume expired before the initiation of the timing as a per cent of FVC to determine whether 10 per cent was a reasonable limit to apply for acceptability of a test. Although 2 SD from the mean of 4.35 per cent were well within this limit, it appears that the technician's judgment of acceptability is sufficient in most cases.

Forced Expiratory Volume↗

PubMed1987

An analysis of decrements in vital capacity as an index of pulmonary oxygen toxicity.

Decrements in vital capacity (% delta VC) were proposed by the Pennsylvania group in the early 1970s as an index of O2-induced lung damage. These workers used the combined effects of PO2 and time of exposure to develop recommendations to limit expected % delta VC. Adopting this general approach, we fitted human pulmonary O2 toxicity data to the hyperbolic equation % delta VC = Bs.(PO2 - B1).(time)B3 using a nonlinear least squares analysis. In addition to the data considered in 1970, our analysis included new data available from the literature. The best fit was obtained when 1) an individual slope parameter, Bs, was estimated for each subject instead of an average slope; 2) PO2 asymptote B1 = 0.38 ATA; and 3) exponent B3 = 1.0. Wide individual variation imposed large uncertainty on any % delta VC prediction. A 12-h exposure to a PO2 of 1 ATA would be expected to yield a median VC decrement of 4%. The 80% confidence limits, however, included changes from +1.0 and -12% delta VC. Until an improved index of pulmonary O2 toxicity is developed, a simplified expression % delta VC = -0.011.(PO2 - 0.5).time (PO2 in ATA and time in min) can be used to predict a median response with little loss in predictability. The limitations of changes in VC as an index are discussed.

Humans↗

PubMed1976

Crying vital capacity. Measurement of neonatal lung function.

Serial measurements of crying vital capacity (CVC), expressed as ml/cm chest circumference, were made by reverse plethysmography during the first 2 weeks of life. Clinically normal babies born at term by elective caesarean section had a smaller mean CVC in the first 2 weeks of life compared with clinically normal term babies born vaginally. In contrast, no significant difference was shown between the mean CVC in term babies born vaginally and those born by urgent caesarean section. Clinically normal term babies born by caesarean section (elective and urgent) had a smaller mean percentage rise of CVC in the first 24 hours of life and a significant delayed rise of CVC from 24-48 hours compared with those born vaginally. Clinically normal preterm babies born vaginally had a smaller mean CVC in the first 2 weeks of life compared with term babies born vaginally, and were characterized by a significant rise of CVC from 5-10 days. Babies with hyaline membrane disease (HMD) had a smaller CVC in the first 2 weeks of life compared with clinically normal preterm babies. Babies of various gestational ages with transient tachypnoea (TT) had a smaller mean CVC in the first 2 weeks of life compared with clinically normal term babies, but a similar mean CVC in the first 72 hours of life compared with clinically normal preterm babies. At each postnatal age the mean CVC of babies with HMD was less than the corresponding mean in babies with TT. All babies with TT had a rise in CVC from 24-48 hours, whereas CVC fell in all babies with HMD except one during this period. CVC is a simple, safe, rapid, and noninvasive test of neonatal lung function, and is a valuable aid to other methods of assessing pulmonary function in the neonate with respiratory distress.

Age Factors↗

PubMedDate not supplied

Interpretation of spirometric tests in asthmatic patients with reduced forced vital capacity.

We have studied 175 consecutive asthmatic patients presenting with: 1) a reversible airflow obstruction, demonstrated by an increase in the forced expiratory volume in 1 second (FEV1) or in the forced vital capacity (FVC) by at least 12% along with an absolute increase of 200 ml versus prebronchodilator values after inhalation of salbutamol; 2) FVC below the lower normal limit before administration of the bronchodilator; and 3) normal FVC or slow vital capacity after bronchodilator. Two different criteria for the lower normal limit of the FEV1/FVC ratio were used to determine whether prebronchodilator spirometric patterns could be considered obstructive or not. The use of the predicted FEV1/FVC ratio as the lower normal limit allowed correct identification of obstruction in 94.9% of the patients, whereas taking the estimated fifth percentile as the lower normal limit of the FEV1/FVC correctly identified obstruction in only 78.9% of the asthmatics. Our results suggest that the predicted FEV1/FVC ratio is an adequate estimate of the lower normal limit in asthmatic patients with reduced FVC in order to distinguish obstructive from nonobstructive patterns.

Adult↗