Sevoflurane and soda lime.
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Anesthesiology↗
Biomedical subjects
W K Grodin
Publications and source records attributed to W K Grodin.
Soda lime adsorption of isoflurane and enflurane.
The authors demonstrated that soda lime will adsorb enflurane or isoflurane as a function of the water content of the soda lime. Various volumes of liquid enflurane or isoflurane were placed in an equilibration flask containing fresh (15% water by weight) or dried soda lime and the vapor phase anesthetic concentrations plotted. When dry soda lime was used, the plot of concentration as a function of volume of liquid added was biphasic: initially flat and then rising linearly. This is qualitatively similar to data reported previously for halothane. The authors hypothesize that drying soda lime produces a molecular sieve-like structure, as adsorption is greatest for molecules with small carbon chain lengths and kinetic diameters, or with structural characteristics such as cis/trans isomerism, which effectively reduce molecular size.
Adsorption↗
Halothane adsorption complicating the use of soda-lime to humidify anaesthetic gases.
If the anaesthetic circle system is arranged to increase the humidity of fresh anaesthetic gases by placing the carbon dioxide absorbent canister between the fresh gas inlet and the patient, drying of the soda-lime can occur. Very dry soda-lime adsorbs significant quantities of halothane. Using fresh soda-lime, effluent halothane concentration reached 50% of the input concentration in 35s, but this time increased to 500 s when dry soda-lime was used. The use of dry soda-lime can result in a slow inhalation induction or in the release of absorbed halothane during a subsequent anaesthetic.
Adsorption↗
Mechanisms of halothane adsorption by dry soda-lime.
Using fresh soda-lime (15% water by weight) the soda lime/air partition coefficient of halothane was found to decrease as a function of vapour phase halothane concentration from 2.40 at 0.3% halothane by volume to 1.15 at 2.6%, but adsorption generally followed Henry's law. However, soda-lime dried to a constant weight and subsequently exposed to various concentrations of halothane adsorbed approximately 320 microlitre of vaporized liquid halothane per 100 g before a measurable concentration of halothane was detected in the vapour phase. Adding additional halothane then caused a linear increase in vapour concentration. We conclude that dry soda-lime can absorb large quantities of halothane by a mechanism which is similar to that of a molecular sieve. After these "high affinity" sites are satisfied, additional halothane is absorbed by a mechanism following Henry's law.
Adsorption↗
Abnormal maturation of sleep states in infants with aborted sudden infant death syndrome.
The time spent in REM, quiet, and indeterminate sleep was computed in 13 aborted SIDS infants and compared to that spent in the same sleep states, in 19 normal infants. Aborted sudden infant death syndrome (SIDS) infants were studied within a week of their aborted SIDS episode and subsequently at monthly intervals through the age of 4 months. Normal infants were studied at 1, 2, 3, and 4 months of age. Sleep staging was performed by two independent observers using electroencephalogram, electrooculogram, electromyogram and behavioral criteria. Although there was an increase in the percentage of time spent in quiet sleep with age in both normal and aborted SIDS infants, the significantly greater regression coefficients in normal infants (6.3 versus 2.9; P less than 0.01) indicate that there are differences in the two groups and suggest a maturational abnormality or delay in sleep state distribution in the aborted SIDS infants.
Age Factors↗
CO2-induced changes in ventilation and ventilatory pattern in normal sleeping infants.
The effect of CO2 on the ventilatory pattern of 18 normal infants was studied during sleep at monthly intervals through the age of 4 mo. Using the barometric method, we measured tidal volume (VT), respiratory cycle time (Ttot), inspiratory time (TI), and expiratory time (TE). Two percent CO2 produced no change in TI and a significant increase in VT and mean inspiratory flow (VT/TI). There was no consistent change in TE or Ttot in either sleep state at any age. The percent increase from base line in instantaneous minute ventilation (VT/Ttot) during REM sleep was similar to that during quiet sleep. We conclude that with inhalation of 2% CO2 in the first 4 mo of life 1) the increase in VT/Ttot results solely from an increase in VT and the percent increase in VT/Ttot is the same in both sleep states and 2) the reflex termination of inspiration by inflation does not play an important role in eupnea during sleep because the increase in VT is not associated with a decrease in TI.
Aging↗