Measurement of Lung Volume by Sulfur Hexafluoride Washout during Spontaneous and Controlled Ventilation

Larsson, Anders; Linnarsson, Dag; Jonmarker, Christer; Jonson, B.; Larsson, Hans; Werner, Olof

doi:10.1097/00000542-198710000-00016

Cited by 74 publications

(62 citation statements)

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“…Analysis of the washout curve allows for the calculation of the FRC, physiological dead space volume, lung clearance index and mean dilution number. The lung clearance index and mean dilution number are commonly used to measure the degree of ventilation homogeneity [9][10][11][12][13][14]. The lung clearance index is calculated as the cumulative expired volume needed to lower the end-tidal tracer gas (SF 6 ) concentration to 1 ⁄ 40 of the starting concentration divided by the FRC, i.e.…”

Section: Methodsmentioning

confidence: 99%

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

Ungern‐Sternberg¹,

Regli²,

Frei³

et al. 2006

Anaesthesia

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SummaryCaudal 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. Various anaesthetic agents, airway instrumentations and ventilation strategies are used in infants and children undergoing anaesthesia. Each of these factors may affect functional residual capacity (FRC), which is one of the most important respiratory parameters of gas exchange. There is very little information available on the magnitude and the relative contribution of these different factors (e.g. neuroaxial blockade with local anaesthetics) on functional residual capacity in anaesthetised children [1][2][3][4].Muscle relaxation induced by caudal epidural anaesthesia with bupivacaine decreases abdominal muscle tone while sparing the muscles of the respiratory system (diaphragm, intercostal muscles). 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. This alteration of the equilibrium between the thoracal and abdominal compartments might affect the functional residual capacity and ventilation homogeneity of the lungs. This study

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Section: Methodsmentioning

confidence: 99%

“…The mean dilution number is the ratio between the first and the zeroth moments of the washout curve. The number of volume turnovers was calculated using the cumulative expired alveolar volume [12,14]. An increase in lung clearance index or mean dilution number reflects a decrease in ventilation homogeneity.…”

Section: Methodsmentioning

confidence: 99%

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

Ungern‐Sternberg¹,

Regli²,

Frei³

et al. 2006

Anaesthesia

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“…PEEP was set to 13 cm H,O. In this animal lung model several studies have proven that PEEP of 13 cm H,O is sufficient to prevent alveolar collapse. This PEEP level was maintained during the whole study.…”

Section: Methodsmentioning

confidence: 99%

Impact of Different Inspiratory Flow Patterns on Arterial CO₂-tension

Markström¹,

Hedlund

Lichtwarck-Aschoff³

et al. 2000

Upsala Journal of Medical Sciences

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Ventilation with decelerating inspiratory flow is known to reduce the dead space fraction and to decrease PaCO2 . Constant inspiratory flow with an end-inspiratory pause (EIP) is also known to increase the removal of CO,.The aim of the study was to elucidate the effect of the pauseho-flow period while both the pattern and rate of inspiratory flow was unchanged, and when the lung was ventilated with sufficient PEEP to prevent end-expiratory collapse.Surfactant depleted piglets were assigned to decelerating or constant inspiratory flow with 24 breaths per minute (bpm) or12 bpm, or to constant flow, without and with an end-inspiratory pause of 25%. By adding an EIP the total time without active inspiratory flow of the respiratory cycle was kept unchanged. Gas exchange, airway pressures, functional residual capacity (using sulfurhexafluoride) and haemodynamics (thermo-dye indicator dilution technique) were measured.Irrespective of ventilatory frequency, PaCOz was lower and serial dead space reduced with decelerating flow, compared with constant inspiratory flow. With an end-inspiratory pause added to constant inspiratory flow, serial dead space was reduced but did not decrease PaCO, .The results of this study corroborate the assumption that total time without active inspiratory flow is important for arterial C0,-tension.

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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 dispensing device delivers SF 6 into the airway in proportion to inspiratory flow, so that the inspired SF 6 is held constant, usually at about 0.5%. 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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Measurement of Lung Volume by Sulfur Hexafluoride Washout during Spontaneous and Controlled Ventilation

Cited by 74 publications

References 0 publications

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

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

Impact of Different Inspiratory Flow Patterns on Arterial CO₂-tension

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

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Measurement of Lung Volume by Sulfur Hexafluoride Washout during Spontaneous and Controlled Ventilation

Cited by 74 publications

References 0 publications

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

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

Impact of Different Inspiratory Flow Patterns on Arterial CO2-tension

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

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Impact of Different Inspiratory Flow Patterns on Arterial CO₂-tension