Measurement of Functional Residual Capacity by Sulfur Hexafluoride in Small-Volume Lungs during Spontaneous Breathing and Mechanical Ventilation

Schulze, Andreas; Schaller, Peter; Töpfer, Andreas; Kirpalani, Haresh

doi:10.1203/00006450-199404000-00020

Cited by 32 publications

(38 citation statements)

References 29 publications

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“…SF 6 washout is a potentially suitable technique for children, including those who require near 100% oxygen to maintain normal Hb saturation. There are a few studies using SF 6 as a washout gas (12)(13)(14) and a mass spectrometer or an infrared analyzer to measure SF 6 concentration. Neither technique is commercially available for routine measurement.…”

mentioning

confidence: 99%

Measurement of Functional Residual Capacity in Rabbits and Children Using an Ultrasonic Flow Meter

Schibler

Henning

2001

Pediatr Res

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A sulfur hexafluoride (SF 6 ) washin/washout technique was developed using an ultrasonic flowmeter to measure functional residual capacity (FRC) during mechanical ventilation. The ultrasonic flowmeter measures simultaneously flow and molar mass of the mainstream gas. Ventilation distribution was studied using moment ratios analysis (alveolar-based mean dilution number). Accuracy and precision of the measurement technique were tested in a mechanical lung model, and the method's sensitivity to changes of FRC was assessed in seven ventilated rabbits and six children. In the mechanical lung model with a volume range from 10 to 60 mL, the mean error of FRC measurement was 0.096 Ϯ 0.9 mL (range, 0 -2 mL). In seven rabbits (mean body weight, 3.6 kg), measurements of FRC and alveolar-based mean dilution number were made at positive end-expiratory pressures (PEEP) of 0, 3, and 6 cm H 2 O. The mean coefficient of variation of 66 FRC-measurements was 5.5% (range, 0 -15.3%). As the applied PEEP increased, mean FRC per kilogram body weight increased from 13.3 Ϯ 3.4 mL/kg (PEEP of 0 cm H 2 O) to 16.7 Ϯ 3.6 mL/kg (PEEP of 3 cm H 2 O) and to 20.8 Ϯ 4.3 mL/kg (PEEP of 6 cm H 2 O). Alveolar-based mean dilution number decreased accordingly from 1.94 Ϯ 0.42 (PEEP ϭ 0; mean Ϯ SD), to 1.91 Ϯ 0.45 (PEEP ϭ 3) and to 1.59 Ϯ 0.35 (PEEP ϭ 6). In the six children, as applied PEEP increased, mean FRC per kilogram increased from 21.1 Ϯ 4.51 mL/kg (PEEP ϭ 0), to 22.4 Ϯ 1.8 mL/kg (PEEP ϭ 5) and 27.2 Ϯ 3.4 mL/kg (PEEP ϭ 10). FRC measurement using the ultrasonic flowmeter is accurate and simple to use in ventilated and spontaneously breathing children. The monitoring of FRC is an important tool for interpreting volume-dependent pulmonary mechanics (e.g. lung elastic recoil pressure or airway resistance). Since the open-circuit MBNW was first described by Darling et al. in 1940 (1), several investigators have used gas washout techniques to measure FRC in spontaneously breathing (2, 3) and mechanically ventilated patients (4 -6). Other gas washout techniques involve helium dilution (7), argon washout (8), or washout of SF 6 (9). Each of these techniques has its own limitations. The MBNW can only be accurately performed if the patient's oxygen requirement does not exceed a certain amount (4 -6).Although MBNW can be performed easily, the considerable changes in gas viscosity during the washout maneuver significantly affect the accuracy of the gas flow measurement by pneumotachography (10, 11). The helium dilution technique is based on a closed circuit, and a leak in the measuring system reduces its accuracy (7). SF 6 washout is a potentially suitable technique for children, including those who require near 100% oxygen to maintain normal Hb saturation. There are a few studies using SF 6 as a washout gas (12-14) and a mass spectrometer or an infrared analyzer to measure SF 6 concentration. Neither technique is commercially available for routine measurement. The infrared analyzer has a low signal-to-noise ratio and a response time of 20 ms or more. Ai...

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confidence: 99%

Measurement of Functional Residual Capacity in Rabbits and Children Using an Ultrasonic Flow Meter

Schibler

Henning

2001

Pediatr Res

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“…The most commonly used are helium (He) dilution (a closed-circuit method), and nitrogen (N 2 ) washout (in its modern form, an open-circuit method). Other gases can be employed, and, over the past decade, a new method has been developed using sulphur hexafluoride [11][12][13][14].…”

Section: Methods For Determining Frcmentioning

confidence: 99%

“…The COV in mechanically ventilated adults is <6.6% [11]. The technique has since been applied to spontaneously breathing adults and infants, as well as those receiving mechanical ventilation [11][12][13][14].…”

Section: In Adultsmentioning

confidence: 99%

Multiple-breath nitrogen washout techniques: including measurements with patients on ventilators

Newth¹,

Enright²,

Johnson³

1997

Eur Respir J

139

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“…52 In vitro studies suggest that the He dilution method is less accurate for small lung volumes, with mean differences of 22% for repeated measurements at 20 ml, in contrast to around 5% for volumes between 40-80 ml. 52 Less variability (mean error of 0.7-2.5%) was observed for low-volume FRC MBW, SF6 measurements obtained with either the ultrasonic flow-meter 27,53 or the infrared mainstream SF 6 analyzer, 23 although the smallest volumes show the highest variability (CV ¼ 16%).…”

Section: What Are the Limitations And Strengths Of The Individual Tecmentioning

confidence: 96%

“…Respiratory mass spectrometers can detect virtually any gas and remain the ''gold standard,'' but they are relatively expensive, bulky, and not currently in widespread use. An infrared mainstream analyzer for SF 6 was developed 18,19 and adapted for use in infants and young [20][21][22] Although used by several groups, [23][24][25] it is not commercially available. The ultrasonic flow-meter (USFM), which measures flow by assessing differences in transit time between two ultrasonic signals through the respiratory gas flow, was modified recently for use in infants.…”

Section: Gas Dilution Techniquesmentioning

confidence: 99%

Lung Function Tests in Neonates and Infants with Chronic Lung Disease of Infancy: Functional Residual Capacity

Hülskamp¹,

Pillow²,

Dinger³

et al. 2005

Pediatric Pulmonology

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Summary. This is the second paper in a review series that will summarize available data and discuss the potential role of lung function testing in infants and young children with acute neonatal respiratory disorders and chronic lung disease of infancy. The current paper addresses the expansive subject of measurements of lung volume using plethysmography and gas dilution/ washout techniques. Following orientation of the reader to the subject area, we focus our comments on areas of inquiry proposed in the introductory paper to this series. The quality of the published literature is reviewed critically, and recommendations are provided to guide future investigation in this field. Measurements of lung volume are important both for assessing growth and development of lungs in health and disease, and for interpreting volume-dependent lung function parameters such as respiratory compliance, resistance, forced expiratory flows, and indices of gas-mixing efficiency. Acute neonatal lung disease is characterized by severely reduced functional residual capacity (FRC), with treatments aimed at securing optimal lung recruitment. While FRC may remain reduced in established chronic lung disease of infancy, more commonly it becomes normalized or even elevated due to hyperinflation, with or without gas-trapping, secondary to airway obstruction. Ideally, accurate and reliable bedside measurements of FRC would be feasible from birth, throughout all phases of postnatal care (including assisted ventilation), and during subsequent long-term follow-up. Although lung volume measurements in extremely preterm infants were described in a research environment, resolution of several issues is required before such investigations can be translated into routine clinical monitoring. Pediatr

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Measurement of Functional Residual Capacity by Sulfur Hexafluoride in Small-Volume Lungs during Spontaneous Breathing and Mechanical Ventilation

Cited by 32 publications

References 29 publications

Measurement of Functional Residual Capacity in Rabbits and Children Using an Ultrasonic Flow Meter

Measurement of Functional Residual Capacity in Rabbits and Children Using an Ultrasonic Flow Meter

Multiple-breath nitrogen washout techniques: including measurements with patients on ventilators

Lung Function Tests in Neonates and Infants with Chronic Lung Disease of Infancy: Functional Residual Capacity

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