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Results for “Functional Residual Capacity”

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PubMed1983

Accurate measurement of functional residual capacity and oxygen consumption of patients on mechanical ventilation.

We developed an apparatus and technique for the simultaneous measurement of functional residual capacity and oxygen uptake (VO2) for use in intensive care unit (ICU) patients. The accuracy of the functional residual capacity measurement was proven using an in vitro lung model and the reproducibility of this measurement was established by use in ICU patients. We tested the accuracy of the VO2 measurement in comparison with two other methods in common use among ICU patients and our method proved accurate. We conclude that this technique for measurement of functional residual capacity and VO2 is highly accurate and easily applied to patients on any mode of mechanical ventilation.

Functional Residual Capacity↗
PubMed2006

The effect of caudal block on functional residual capacity and ventilation homogeneity in healthy children.

Caudal block results in a motor blockade that can reduce abdominal wall tension. This could interact with the balance between chest wall and lung recoil pressure and tension of the diaphragm, which determines the static resting volume of the lung. On this rationale, we hypothesised that caudal block causes an increase in functional residual capacity and ventilation distribution in anaesthetised children. Fifty-two healthy children (15-30 kg, 3-8 years of age) undergoing elective surgery with general anaesthesia and caudal block were studied and randomly allocated to two groups: caudal block or control. Following induction of anaesthesia, the first measurement was obtained in the supine position (baseline). All children were then turned to the left lateral position and patients in the caudal block group received a caudal block with bupivacaine. No intervention took place in the control group. After 15 min in the supine position, the second assessment was performed. Functional residual capacity and parameters of ventilation distribution were calculated by a blinded reviewer. Functional residual capacity was similar at baseline in both groups. In the caudal block group, the capacity increased significantly (p < 0.0001) following caudal block, while in the control group, it remained unchanged. In both groups, parameters of ventilation distribution were consistent with the changes in functional residual capacity. Caudal block resulted in a significant increase in functional residual capacity and improvement in ventilation homogeneity in comparison with the control group. This indicates that caudal block might have a beneficial effect on gas exchange in anaesthetised, spontaneously breathing preschool-aged children with healthy lungs.

Anesthesia, Caudal↗
PubMed1985

The effect of ketamine on the functional residual capacity in young children.

The effect of ketamine on the functional residual capacity (FRC) was measured in nine ASA class I children prior to elective surgery. FRC was determined by the closed-circuit helium dilution method on the day prior to surgery in the awake state and also following induction of anesthesia on the day of the operation. Anesthesia consisted of ketamine by continuous intravenous infusion following preanesthetic sedation with atropine and triclofos or flunitrazepam. There were no significant differences in FRC between the measurements in the awake state and anesthetized (392 +/- 43 SEM ml, and 411 +/- 53 SEM ml, respectively), and the authors conclude that ketamine does not affect resting lung volume in young children.

Anesthesia, General↗
PubMed1982

Normal values of functional residual capacity in the sitting and supine positions.

The measurement of functional residual capacity (FRC) has assumed new importance in the diagnosis of acute respiratory failure. However few reference values exist for FRC in supine positions for both sexes. We measured the FRC in 100 healthy subjects with the helium dilution closed circuit method in the sitting and supine positions. There were 50 women aged 20 to 63 years and 50 men aged 22 to 65 years. Fifty five subjects were smokers (25 women and 30 men) but no significant differences were found between FRC of smokers and nonsmokers. The FRC always decreased when the subject changed from the sitting to supine position. In this study, the correlation coefficients between FRC and height were statistically significant for both sexes, the influence of age and weight on FRC being negligible. Our results provide useful reference values for FRC in the supine position.

Adult↗
PubMed1991

Establishment of functional residual capacity in infants delivered vaginally and by elective cesarean section.

Functional residual capacity (FRC) was measured with an open circuit N2 washout method in 20 vaginally born infants and 15 delivered by cesarean section, 30 and 120 min after birth. Umbilical artery blood was collected and analyzed for pH and catecholamine concentration. FRC was significantly higher in the cesarean section infants than in the vaginally delivered infants at 120 min of age (23.8 versus 16.8 ml/kg). The cesarean section infants also tended to have lower tidal volumes and higher respiratory frequencies than infants delivered vaginally. No significant correlation was found between catecholamine levels in umbilical artery and FRC in either group although there was a significant correlation between catecholamine level at birth and the increase of FRC from 30 to 120 min in the cesarean section group. It is suggested that the higher FRC, higher respiratory frequency and lower tidal volume in the cesarean section infants is an adaptation to a higher pulmonary water content to ensure an efficient gas exchange with the least respiratory work.

Catecholamines↗
PubMed2005

Open lung ventilation improves functional residual capacity after extubation in cardiac surgery.

OBJECTIVE: After cardiac surgery, functional residual capacity (FRC) after extubation is reduced significantly. We hypothesized that ventilation according to the open lung concept (OLC) attenuates FRC reduction after extubation. DESIGN: A prospective, single-center, randomized, controlled clinical study. SETTING: Cardiothoracic operating room and intensive care unit of a university hospital. PATIENTS: Sixty-nine patients scheduled for elective coronary artery bypass graft and/or valve surgery with cardiopulmonary bypass. INTERVENTIONS: Before surgery, patients were randomly assigned to three groups: (1) conventional ventilation (CV); (2) OLC, started after arrival in the intensive care unit (late open lung); and (3) OLC, started directly after intubation (early open lung). In both OLC groups, recruitment maneuvers were applied until Pao2/Fio2 was >375 Torr (50 kPa). No recruitment maneuvers were applied in the CV group. MEASUREMENTS AND MAIN RESULTS: FRC was measured preoperatively and 1, 3, and 5 days after extubation. Peripheral hemoglobin saturation (Spo2) was measured daily till the third day after extubation while the patient was breathing room air. Hypoxemia was defined by an Spo2 value < or =90%. Averaged over the 5 postoperative days, FRC was significantly higher in the early open lung group and tended to be higher in the late open lung group, in comparison with the CV group (mean +/- sem: CV, 1.8 +/- 0.1; late open lung,1.9 +/- 0.1; and early open lung, 2.2 +/- 0.1l). In the CV group, 37% of the patients were hypoxic on the third day after extubation, compared with none of the patients in both OLC groups. CONCLUSIONS: After cardiac surgery, earlier application of OLC resulted in a significantly higher FRC and fewer episodes of hypoxemia than with CV after extubation.

Adult↗
PubMed1993

[Percentile curves of functional residual capacity of newborn infants].

BACKGROUND: Helium dilution or nitrogen washout techniques are commonly used to measure the functional residual capacity (FRC) in newborn babies. For both techniques equipment is available. Its clinical application, however, was difficult since there were no FRC reference ranges for the different weight groups of newborn infants; reference studies are very time consuming and cause several technical and ethical problems. METHODS: Statistical methods were used to evaluate several results from the literature and to exclude significantly differing data of some authors. Measured values of FRC were related to body weight, and the percentiles of FRC/kg were estimated by the smoothed cumulative distribution function of the pooled data. RESULTS: No significant differences were found between the results of helium dilution and nitrogen washout techniques. The distribution of 178 results showed a significant skewedness (x5% = 18.3 ml/kg; x50% = 27.5 ml/kg x95% = 42.8 ml/kg), which could also be seen in the percentile curves calculated approximately, assuming a linear development of functional residual capacity with body weight. CONCLUSION: Percentile curves describe best the development and interindividual variability of FRC in newborn babies as our evaluation could show. We conclude that the nonparametric estimation of percentiles is more adequate for the description than the use of simple regression models.

Birth Weight↗
PubMed2002

Functional residual capacity: the human windbag.

Like the windbag of a bagpipe, the functional residual capacity (FRC) is the lung volume that acts as a reservoir of air for physiologic use. This reserve volume is particularly important during the period of apnea that occurs during induction of general anesthesia. The balance of the inward elastic recoil of the lung and the outward chest wall forces determines the FRC. Inward recoil forces are dependent on the interaction between the fibrous skeleton of the lung tissue and the alveolar surface tension regulated by pulmonary surfactant. Positioning and the use of inhaled and intravenous anesthetics influence outward chest wall forces. Factors that affect the FRC may be altered by volume recruitment maneuvers such as administration of vital capacity breaths, the application of positive end-expiratory pressure, and/or maintenance of anesthesia with a fraction of inspired oxygen of less than 1.0. This course reviews the basic anatomy and physiology of the FRC during the perioperative period. Understanding the processes that contribute to intraoperative loss of lung volume and knowledge of interventions that can allay them are paramount to providing a reliable and safe general anesthetic.

Functional Residual Capacity↗
PubMedDate not supplied

Influence of increased anatomical dead space no functional residual capacity of lungs and the lung clearance index.

A study of the influence of added anatomical dead space on the functional residual capacity of the lung was carried out on a total number of 40 healthy subjects of ages ranging between 21 and 50 years. The functional residual capacity was found to decrease as additional dead space was introduced in the breathing circuit. This decrease was associated with an increase in tidal volume, lung functions, as given by the lung clearance index, were found to deteriorate with each addition of dead space. There was also an increase in pulse rate in all age groups.

Adult↗
PubMed1996

Functional residual capacity in healthy preschool children.

The purpose of this study was to evaluate the feasibility of routine functional residual capacity (FRC) measurements in healthy preschool children aged 2.7-6.4 yrs. Furthermore, accuracy and reproducibility were investigated and normal values were collected. A mass-produced closed-circuit helium dilution device (rolling seal) was used. Selection of the 113 healthy children (from the 571 measured) was based on an extensive personal and family history questionnaire and on clinical examination before measurements were performed. With three successive attempts it was possible to achieve at least two reproducible measurements in 73% of the children (repeatability coefficient 95.3 mL). The main problems were leakage at the corner of the mouth and irregular breathing pattern. The mean time to perform a measurement was 113 s. Mean FRC was significantly higher in boys than in girls: 778 versus 739 mL for a body length of 110 cm (p<0.05). FRC correlated with height (H) (r=0.69), weight (W) (r=0.56), age (A) (r=0.62) and all three combined (r=0.70): FRC = -534.89 + 1.84 x W (kg) + 10.07 x H (cm) + 2.51 x A (months). When a power or exponential function was used to describe FRC as a function of height, the results were not superior to the linear regression (r=0.69): FRC (mL) = -766.2 + 13.8 x H (cm) (r=0.69) or FRC (L) = 0.620 x H (m)(2.03) (r=0.69) or FRC (mL)= 99.5 x e(0.018xH (cm)) (r=0.69). Among these, we recommend the power function because it will better fit broader height ranges. Reliable functional residual capacity measurements can be routinely performed in preschool children with a mass-produced device. Reference values were collected for children 95-125 cm in height.

Body Height↗
PubMed1993

Comparison of helium dilution and nitrogen washout measurements of functional residual capacity in premature infants.

Comparison has been made of measurements of functional residue capacity (FRC) by a helium gas dilution (He) and a nitrogen washout (N2) technique. Twenty infants (median gestational age, 29.5 weeks) were studied at a median postnatal age of 25 days. No infant was oxygen dependent. The coefficient of repeatability of FRC (He) was 6.4 mL/kg and of FRC (N2), 6.3 mL/kg. The coefficient of repeatability of the two methods combined was 13.8 mL/kg. In 10 infants the results of two techniques differed by more than 20% of the mean FRC; those infants were born at a significantly earlier gestation than the rest of the cohort (P < 0.01). We conclude that, except in very immature infants, techniques for measuring FRC (He) and FRC (N2) yield reproducible and comparable results in convalescent premature infants.

Female↗
PubMed1981

A practical procedure for measuring functional residual capacity during mechanical ventilation with or without PEEP.

The measurement of functional residual capacity (FRC) in patients receiving mechanical ventilation may provide valuable data in the assessment and management of acute respiratory failure. Previous descriptions of apparatus and techniques for FRC measurement have either been inapplicable to patients receiving positive end-expiratory pressure (PEEP), or insufficiently detailed to allow convenient duplication in the clinical setting. The authors describe a helium rebreathing method for bedside determination of FRC which can be performed during ventilation with PEEP and which is applicable in patients with prolonged equilibration times. The method is both reproducible in patients (variation from mean FRC: +/- 2.2%) and accurate (coefficient of variation from in vitro FRC of 3000 ml: +/- 1.7%). The apparatus and assembly are described in detail and require only components which are readily available commercially, so that they may be applicable to clinical use in a general hospital.

Adult↗
PubMed1990

An automated bedside method for measuring functional residual capacity by N2 washout in mechanically ventilated children.

Beside measurement of functional residual capacity (FRC) in ventilated children is impractical. Using a simple technique based on open circuit N2 washout, we measured FRC in ventilated children. The system was evaluated in the laboratory and in patients. Using a mechanical lung, the reproducibility of 200 studies over a range of 100-500 mL at each of four different flow rates (10 determinations at each level) was very high with a mean coefficient of variation of 2.3% (range 0.5-5.1%). Linearity of the integrated N2 signal for volumes of 100-500 mL washed out at different flow rates was excellent (range 7.4-17.9 L/min), r = 0.99. The mean difference between measured and preset mechanical lung volumes was 2.4% (range 0-4.6%). In vivo, reproducibility of six to 10 FRC determinations in each of 30 children gave a mean coefficient of variation of 2.7%. Comparison to the conventional Douglas bag collection method showed a high correlation (r = 0.97). We conclude that this is an easy, highly reproducible, and accurate method for FRC determination suitable to ventilated infants and children.

Child↗
PubMed1981

A radiographic method for measuring steady-state functional residual capacity in the supine patient. A method suitable for sleep studies.

We have devised a method to measure functional residual capacity (FRC) in the recumbent, spontaneously breathing patient. Simultaneous anteroposterior and lateral chest radiographs were exposed at the end of an exhalation, as determined by tracings of flow sensed by a nasal thermistor. The volume of the lungs was then planimetrically measured. Functional residual capacity was sequentially measured in 20 supine subjects, both by a helium dilution technique and by the radiographic technique. Planimetric measurement of FRC correlated well with the helium dilution technique, with a range of FRC measurements from 1.53 to 6.41 L (r = 0.94). This method of measuring lung volume should be useful in evaluating changes in FRC associated with different sleep stages and in explaining the mechanisms causing nocturnal oxygen desaturation in patients with chronic obstructive lung disease.

Functional Residual Capacity↗
PubMed1989

Changes in functional residual capacity in response to bronchodilator therapy among young asthmatic children.

Measurements of functional residual capacity (FRC) by helium gas dilution and peak expiration flow rate (PEFR) were made in 63 young asthmatic children aged 2 and 7 years before and after bronchodilator therapy. All 63 children tolerated two measurements of FRC, but only 33 children were able to perform the peak flow maneuver. Bronchodilator therapy was associated with significant change in FRC in the majority (80%) of children; in some, however, this change was an increase rather than a decrease. The change in FRC was significantly correlated with both prebronchodilator FRC and the change in PEFR. An increase in FRC following bronchodilator therapy was more common in children with severe and symptomatic asthma. We suggest that changes in FRC may be used in asthmatic children to demonstrate bronchodilator responsiveness, particularly in those too young to perform other respiratory function tests.

Asthma↗