Abstract
Objective: To determine whether the vapor pressure of desflurane could be decreased by using a solvent to reduce the anesthetic molar fraction in a solution (Raoult's Law). We hypothesized that such an anesthetic mixture could produce anesthesia using a nonprecision vaporizer instead of an agent-specific, electronically controlled, temperature and pressure compensated vaporizer currently required for desflurane administration. Animal: One healthy adult female dog. Procedure and results: Propylene glycol was used as a solvent for desflurane, and the physical characteristics of this mixture were evaluated at various molar concentrations and temperatures. Using a circle system with a breathing bag attached at the patient end and a mechanical ventilator to simulate respiration, an in-circuit, nonprecision vaporizer containing 40% desflurane and 60% propylene glycol achieved an 11.5% ± 1.0% circuit desflurane concentration with a 5.2 ± 0.4 (0 = off, 10 = maximum) vaporizer setting. This experiment was repeated with a dog attached to the breathing circuit under spontaneous ventilation with a fresh gas flow of 0.5 L minute-1. Anesthesia was maintained for over 2 hours at a mean vaporizer setting of 6.2 ± 0.4, yielding mean inspired and end-tidal desflurane concentrations of 8.7% ± 0.5% and 7.9% ± 0.7%, respectively. Conclusions and clinical relevance: Rather than alter physical properties of vaporizers to suit a particular anesthetic agent, this study demonstrates that it is also possible to alter physical properties of anesthetic agents to suit a particular vaporizer. However, propylene glycol may not prove an ideal solvent for desflurane because of its instability in solution and substantial-positive deviation from Raoult's Law.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 275-280 |
| Number of pages | 6 |
| Journal | Veterinary Anaesthesia and Analgesia |
| Volume | 33 |
| Issue number | 5 |
| DOIs | |
| State | Published - Sep 2006 |
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Keywords
- Azeotrope
- Boiling point
- Colligative properties
- Desflurane
- I-653
- Raoult's Law
ASJC Scopus subject areas
- veterinary(all)
Cite this
A technique to depress desflurane vapor pressure. / Brosnan, Robert J; Pypendop, Bruno H.
In: Veterinary Anaesthesia and Analgesia, Vol. 33, No. 5, 09.2006, p. 275-280.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - A technique to depress desflurane vapor pressure
AU - Brosnan, Robert J
AU - Pypendop, Bruno H
PY - 2006/9
Y1 - 2006/9
N2 - Objective: To determine whether the vapor pressure of desflurane could be decreased by using a solvent to reduce the anesthetic molar fraction in a solution (Raoult's Law). We hypothesized that such an anesthetic mixture could produce anesthesia using a nonprecision vaporizer instead of an agent-specific, electronically controlled, temperature and pressure compensated vaporizer currently required for desflurane administration. Animal: One healthy adult female dog. Procedure and results: Propylene glycol was used as a solvent for desflurane, and the physical characteristics of this mixture were evaluated at various molar concentrations and temperatures. Using a circle system with a breathing bag attached at the patient end and a mechanical ventilator to simulate respiration, an in-circuit, nonprecision vaporizer containing 40% desflurane and 60% propylene glycol achieved an 11.5% ± 1.0% circuit desflurane concentration with a 5.2 ± 0.4 (0 = off, 10 = maximum) vaporizer setting. This experiment was repeated with a dog attached to the breathing circuit under spontaneous ventilation with a fresh gas flow of 0.5 L minute-1. Anesthesia was maintained for over 2 hours at a mean vaporizer setting of 6.2 ± 0.4, yielding mean inspired and end-tidal desflurane concentrations of 8.7% ± 0.5% and 7.9% ± 0.7%, respectively. Conclusions and clinical relevance: Rather than alter physical properties of vaporizers to suit a particular anesthetic agent, this study demonstrates that it is also possible to alter physical properties of anesthetic agents to suit a particular vaporizer. However, propylene glycol may not prove an ideal solvent for desflurane because of its instability in solution and substantial-positive deviation from Raoult's Law.
AB - Objective: To determine whether the vapor pressure of desflurane could be decreased by using a solvent to reduce the anesthetic molar fraction in a solution (Raoult's Law). We hypothesized that such an anesthetic mixture could produce anesthesia using a nonprecision vaporizer instead of an agent-specific, electronically controlled, temperature and pressure compensated vaporizer currently required for desflurane administration. Animal: One healthy adult female dog. Procedure and results: Propylene glycol was used as a solvent for desflurane, and the physical characteristics of this mixture were evaluated at various molar concentrations and temperatures. Using a circle system with a breathing bag attached at the patient end and a mechanical ventilator to simulate respiration, an in-circuit, nonprecision vaporizer containing 40% desflurane and 60% propylene glycol achieved an 11.5% ± 1.0% circuit desflurane concentration with a 5.2 ± 0.4 (0 = off, 10 = maximum) vaporizer setting. This experiment was repeated with a dog attached to the breathing circuit under spontaneous ventilation with a fresh gas flow of 0.5 L minute-1. Anesthesia was maintained for over 2 hours at a mean vaporizer setting of 6.2 ± 0.4, yielding mean inspired and end-tidal desflurane concentrations of 8.7% ± 0.5% and 7.9% ± 0.7%, respectively. Conclusions and clinical relevance: Rather than alter physical properties of vaporizers to suit a particular anesthetic agent, this study demonstrates that it is also possible to alter physical properties of anesthetic agents to suit a particular vaporizer. However, propylene glycol may not prove an ideal solvent for desflurane because of its instability in solution and substantial-positive deviation from Raoult's Law.
KW - Azeotrope
KW - Boiling point
KW - Colligative properties
KW - Desflurane
KW - I-653
KW - Raoult's Law
UR - http://www.scopus.com/inward/record.url?scp=33747094402&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33747094402&partnerID=8YFLogxK
U2 - 10.1111/j.1467-2995.2005.00270.x
DO - 10.1111/j.1467-2995.2005.00270.x
M3 - Article
C2 - 16916349
AN - SCOPUS:33747094402
VL - 33
SP - 275
EP - 280
JO - Veterinary Anaesthesia and Analgesia
JF - Veterinary Anaesthesia and Analgesia
SN - 1467-2987
IS - 5
ER -