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Biomedical subjects

R L Rayburn

Publications and source records attributed to R L Rayburn.

7 recordsLinked to original sources
PubMed1980

Humidity in children and adults using the controlled partial rebreathing anesthesia method.

The authors examined inspired humidity using a controlled partial rebreathing anesthesia method (CPRAM) and a circle system in 16 healthy adults and five healthy children. The patients were divided into five study groups (A-E). All patients except those in Group E were anesthetized with fentanyl, pancuronium, nitrous oxide-oxygen, 66-33 per cent, and their lungs were mechanically ventilated; patients in Group E received halothane and nitrous oxide-oxygen, 66-33 per cent, with spontaneous ventilation. Group A (five children) had inspired hummidity measured within a modified coaxial (Bain) anesthesia circuit using CPRAM. Groups B and C (five adults each) had humidity measured within the modified coaxial circuit and at the end of a non-modified coaxial circuit using CPRAM. Groups D and E (three adults each) had humidity measured in the semi-closed and closed circle systems, respectively. Initial, mid-, and end-inspired humidity were measured in all groups for two hours by interrupting the controlled ventilation at 30-min intervals, except in patients of Group E, who had humidity measured at similar intervals for two hours during spontaneous ventilation. No significant difference was found among initial, mid-, or end-inspired humidity, nor was there a significant difference between inspired humidities in children and in adults using CPRAM. The humidity measured in adults within the circuit near the endotracheal tube was not significantly different from that measured distal to the fresh gas flow. The humidities in all CPRAM patients exceeded those of both the semiclosed and closed circle systems, stabilizing within 30 min and remaining constant between 24 and 26 mg H2O/1.

Adult↗
PubMed1978

A new concept in controlled ventilation of children with the Bain anesthetic circuit.

The Bain anesthesia circuit was studied as a semi-open or partial rebreathing system during controlled ventilation in 16 children weighing from 7.5 to 48 kg. During anesthesia the lungs were ventilated with a volume ventilator set at three times the calculated alveolar ventilation to provide optimum mixing in the exhalation tube of the Bain circuit. Fresh gas inflow rates initially were set equal to the calculated alveolar ventilation, and after 30 to 45 min, PCO2, PO2 and pH values were measured. At the same time, the fractional concentration of mixed expired carbon dioxide (FECO2) was recorded from a capnograph inserted between the ventilator and the Bain circuit. After initial readings, the fresh gas inflow was varied over a range of 1,400-3,000 ml/m2/min at 20-min intervals, with the arterial blood-gas values and FECO2 recorded at each setting. The results indicate that a lower fresh gas inflow than previously recommended can be used safely in children. When the minute ventilation is three times the fresh gas inflow, values for FECO2 correlate closely with PaCO2 values; with a fresh gas inflow of 2,500 ml/m2/min,PaCO2 values can be maintained near 40 torr.

Anesthesia, General↗
PubMedDate not supplied

Ketamine and intraocular pressure in children.

The effect of ketamine on intraocular pressure (IOP) was studied in 10 children. Control IOP values were determined prior to induction of anesthesia, following premedication with atropine alone or in combination with pentobarbital and meperidine. After the IM injection of 8 mg/kg of ketamine, the IOP was determined at 5, 10, 15, and 20 minutes. Mean (+/- SD) IOP values before and after ketamine were 22.2 +/- 4.8 and 16.7 +/- 3.3 torr (p less than 0.001), respectively. The authors believe that the reduction in IOP was not due to ketamine, per se, but rather to lack of patient relaxation and cooperation during control measurements. At the end of 20 minutes, a second dose of ketamine, this time 1 mg/kg IV, was given and measurements were repeated at the same intervals. In 5 patients, the effects on IOP of d-tubocurarine, endotracheal intubation, and N2O inhalation also was evaluated. A significant increase (6.7 torr) in IOP was observed only after endotracheal intubation. The authors conclude that ketamine does not raise IOP in the healthy pediatric patient and, therefore, can be used for ophthalmic procedures requiring sedation or anesthesia.

Anesthesia, Inhalation↗