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J A Bain

Publications and source records attributed to J A Bain.

10 recordsLinked to original sources
PubMed1990

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

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.

Adolescent↗
PubMed1979

Bain circuit.

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Anesthesia↗
PubMed1977

Carbon dioxide output and elimination in children under anaesthesia.

The requirements for fresh gas inflow with the Bain breathing circuit in children was examined by determining the PaCO2 in 46 children during controlled ventilation with a total fresh gas inflow of 3.5 l/min and by measuring the carbon dioxide output in 83 children under anaesthesia. It could be shown that all children below 40 kg body weight had a PaCO2 below 40 torr (5.32 kPa) and the PaCO2 paralleled the body weight, i.e., the lowest carbon dioxide tension was seen in children under 10 kg. As expected, the highest carbon dioxide output was found in children below 5 kg body weight; the carbon dioxide output per kilogram decreased with increasing body weight up to 30-35 kg and remained at that level in larger children. Children in their teens, although they may have attained adult body weight, had a higher carbon dioxide output than adults. Based on these findings, our recommendation of a total fresh gas inflow of 3.5 1/min for all children would appear adequate for a body weight up to 35 kg on controlled ventilation. In children under 10 kg body weight, a reduction of the total fresh gas flow to two litres per minute will avoid marked respiratory alkalosis. For children over 35 kg, a fresh gas flow of 100 ml/kg/min should be satisfactory during controlled ventilation.

Adolescent↗
PubMed1976

Carbon dioxide output in anaesthesia.

In a Mapleson D circuit the carbon dioxide content of gases, sampled at the breathing bag or near the bellows of the ventilator, is virtually constant throughout the phases of respiration. Assuming that after induction of anaesthesia the fresh gas inflow, if kept constant, is essentially equal in volume to the gas vented at the expiratory valve, CO2 output can be calculated by multiplying the fresh gas inflow by the CO2 content of the vented gas measured with a suitable CO2 analyzer. Anaesthesia with nitrous oxide-oxygen, supplemented with low doses of alphaprodine or halothane was compared in two groups of young patients who underwent dental surgery and who were breathing spontaneously. While the CO2 output in the group supplemented with alphaprodine increased from about 100 to 130 ml/m2/min, the halothane group showed a constant CO2 output of about 90 ml/m2/min followed by a significant rise within 5 minutes after halothane was discontinued. In 42 patients on controlled ventilation, no significant difference was found in the CO2 output estimated one hour after induction of anaesthesia in nitrous oxide-oxygen anaesthesia supplemented by halothane, ethrane or alphaprodine. The values obtained were 87 +/- 11 ml/m2/min for halothane (11 patients), 98 +/- 19 ml/m2/min for ethrane (14) and 93 +/- 13 ml/m2/min for the narcotic supplemented anaesthesia (17). The mean CO2 output for all 42 patients was 93 +/- 14 ml/m2/min. Six markedly obese patients under the same anaesthetic technique had a CO2 output of 114 +/- 17 ml/m2/min; however, their CO2 output was similar to normal patients when calculated on the basis of body weight. A marked increase in CO2 output to a mean of 160 +/- 25 ml/m2/min was found in eight patients undergoing operation while on hyperalimentation. The technique described appears suitable to monitor CO2 output under anaesthesia. In order to avoid hypercarbia when using a partial rebreathing system, the fresh gas inflow must be increased above recommended values in cases with increased metabolic activity (e.g. patients receiving hyperalimentation). In obese patients the fresh gas inflow should be calculated on the basis of body weight.

Adult↗
PubMed1975

Prediction of arterial carbon dioxide tension during controlled ventilation with a modified Mapleson D system.

Based on measurements of arterial CO2 tension in 132 adult patients, a curve was constructed relating fresh gas inflow and arterial CO2 tension for a modified Mapleson D system. In patients on controlled ventilation using a ventilating volume greater than the predicted respiratory minute volume, it was found that the arterial Pco2 can be predicted from the fresh gas inflow with an accuracy sufficient to be clinically useful.

Adult↗
PubMed1975

A modification of the Bird Mark VIII ventilator to deliver continuous positive pressure breathing and intermittent mandatory ventilation.

A Bird Mark VIII ventilator was modified to produce a simple and inexpensive C.P.P.B. and I.M.V. circuit. A Bain Breathing Circuit allowed the manifold to be placed near the ventilator. The negative pressure and flow to the injector produce C.P.P.B. The continuous flow of the Mapleson D Modification furnished constant inflow to provide humidified fresh gas to the reservoir and the patient circuit for I.M.V. An accompanying graph illustrates suggested flow rates and CO2 elimination (Figure 2).

Humans↗