CONTROLLED VENTILATION WITH THE MAPLESON D SYSTEM: A Theoretical and Experimental Study

Seeley, H. F.; Barnes, P.K.; Conway, C.M.

doi:10.1093/bja/49.2.107

Cited by 23 publications

(19 citation statements)

References 11 publications

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“…As shown in this study, monitoring of P E 0 co 2 allowed less fresh gas flow than was previously recommended to maintain normocapnia [7,8]. The degree of rebreathing of carbon dioxide was easily controlled based on the monitor's values, and unintentional hypocapnia due to too high a fresh gas flow was prevented, whilst still allowing the use of physiological tidal volumes and a normal respiratory rate.…”

Section: Discussionmentioning

confidence: 78%

A new device to reduce the consumption of a halogenated anaesthetic agent*

Enlund¹,

Wiklund

Lambert

2001

Anaesthesia

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SummaryWe report the first clinical application of a new anaesthetic agent-saving device. The principles of a heat±moisture exchanger have been further developed to create a device that reduces inhalational agent consumption. Sixteen patients were randomly allocated to receive isoflurane through either a vaporiser or through the agent-saving device. A coaxial Mapleson D system (Bain) was used in both groups. A standard ventilatory setting was used, aiming for normocapnia. Mean (SD) isoflurane consumption was 24.5 (2.8) ml.MAC-hour 21 with the vaporiser, compared with 15.2 (3.0) ml.MAC-hour 21 with the new device (p , 0.05). This corresponded to a 40% saving in the consumption of isoflurane. The amount of isoflurane that was scavenged to the atmosphere was reduced by an average of 55%.

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Section: Discussionmentioning

confidence: 78%

A new device to reduce the consumption of a halogenated anaesthetic agent*

Enlund¹,

Wiklund

Lambert

2001

Anaesthesia

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“…Even if many factors affect the degree of rebreathing, such as the VD/VT ratio of the patient and the respiratory flow pattern (6,17,18), these factors will be insignificant when compared to the impact of the vFG when small O F , / vE ratios are used (6,8). was 7.38 f 0.05 with a range of 7.29-7.51.…”

Section: Resultsmentioning

confidence: 99%

“…One of the other children with a low pH was a 3-year-old girl undergoing a liver transplant who had a pure as harmless and is often said to contribute to anaesthesia. The resulting Paco, will, however, be affected mainly by the given vFG and thus remain constant despite these changes in minute ventilation and dead space ratio (6,8). One of the most important advantages of the Mapleson D circuit is its ability to maintain normocapnea with a large minute ventilation.…”

Section: Resultsmentioning

confidence: 99%

“…the fresh gas flow which is not lost through the excess valve) times the fresh gas flow (6,8), which gives us the equation: the fresh gas flow which is not lost through the excess valve) times the fresh gas flow (6,8), which gives us the equation:…”

Section: Construction Of the Nomogrammentioning

confidence: 99%

“…5. From the theoretical analysis of Seeley et al ( 8 ) , Rose & Froese (6) concluded that the resulting alveolar fraction of carbon dioxide (F,co,) in a Bain system during rebreathing conditions will be equal to the formula VCo2/f. Many factors, such as the carbon dioxide elimination (Vco2), the given fresh gas flow, the respiratory flow pattern, the V,/V, ratio and the given minute ventilation will affect rebreathing in a Mapleson D circuit, but when the VFG/VE ratio is well below 1.0, the OF, and the carbon dioxide output will be the most important factors governing the resulting Paco, (6,8).…”

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confidence: 99%

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Predicted normocapnea in infants and children using the Bain circuit with controlled ventilation

Jönsson

Bain

Lee

1990

Acta Anaesthesiol Scand

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We have constructed a nomogram for fresh gas flow (VFG) and minute ventilation (VE) for paediatric anaesthesia during controlled ventilation using the Bain coaxial Mapleson D circuit. VFG was based upon the assumption of a high fresh gas utilization because of a low VFG/VE ratio (0.67) and known figures of carbon dioxide elimination. The formulas VFG = 27.8 x VCO2 and VE = 1.5 x VFG were used to calculate the necessary flows to generate normocapnea. The nomogram was evaluated in 59 children (6-62 kg, age 5 months-14 years). PaCO2 (mean +/- s.d.) was 5.0 +/- 0.5 kPa (38 +/- 4 mmHg) with a total range of 3.9-6.3 kPa (29-47 mmHg). Ninety percent of the children had a PaCO2 of 5.7 kPa (43 mmHg) or lower. There was no correlation between body weight and PaCO2. Hence, there was no difference in mean values between children below or above a body weight of 20 kg.

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Capnography and the bain circuit I: A computer model

Beneken¹,

Gravenstein²,

Gravenstein³

et al. 1985

J Clin Monitor Comput

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The Mapleson D anesthesia breathing system has no valves and allows rebreathing of carbon dioxide. Its coaxial version is known as the Bain system. The interpretation of capnograms obtained during its use requires an understanding of the interrelationships of patient and system variables. Toward that end, a systematic description of mechanical ventilation with the Bain circuit was undertaken based on the physical laws of gas transport. The mathematical formulation of the model contains the relations between pressure, flow, and volume in the tube, alveolar space, and ventilator. The flows, calculated from these relations, are used to determine the CO2 concentrations in the different parts of the model. Two sets of data are used--patient and system. The patient data, used to solve the equations numerically, are lung-thorax compliance, CO2 inflow into alveolar space (CO2 production), functional residual capacity, dead space volume, airway resistance, and respiratory quotient. The ventilation system data comprise the dimensions and volumes of the Bain circuit, ventilator, connectors, and tubes; spill valve pressure; resistances to flow in the individual tube parts; ventilator settings; and fresh-gas flow rates. After incorporation of a volunteer's respiratory variables into the model, capnograms obtained from the model compared well with those obtained from the volunteer. The structure of the model is such that it permits easy introduction or changes of patient and system variables to obtain individual results or model specific circumstances. This flexibility makes it a useful tool for understanding the properties of the Bain circuit under a variety of clinical circumstances. The results may be displayed in a number of different ways.

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CONTROLLED VENTILATION WITH THE MAPLESON D SYSTEM: A Theoretical and Experimental Study

Cited by 23 publications

References 11 publications

A new device to reduce the consumption of a halogenated anaesthetic agent*

A new device to reduce the consumption of a halogenated anaesthetic agent*

Predicted normocapnea in infants and children using the Bain circuit with controlled ventilation

Capnography and the bain circuit I: A computer model

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