Abstract
Objective
To determine whether predictable alveolar concentrations of sevoflurane are reliably
produced in dogs when liquid sevoflurane is injected into closed circuit breathing
systems, as calculated by Lowe's square-root-of-time anaesthetic uptake model, and
to confirm the validity of the model using soda lime and calcium hydroxide lime.
Study design
Prospective clinical study.
Animals
Eleven healthy dogs with a mean body mass of 34 ± 9 kg scheduled for pelvic limb orthopaedic
surgery.
Materials and methods
Following pre-anaesthetic medication, anaesthesia was induced with propofol and maintained
with sevoflurane in a closed circle system. Epidural anaesthesia was performed with
morphine and bupivacaine. Liquid sevoflurane was injected into the circuit by syringe,
using dosages and time intervals derived from Lowe's square-root-of-time anaesthetic
uptake model. The target alveolar concentration chosen was 1.1 × MAC (2.6% end-tidal
sevoflurane). Either soda lime (group S; n = 6) or calcium hydroxide lime (Amsorb; group A; n = 5) were used for CO2 absorption. Sevoflurane concentration and the respiratory gas composition were measured
with an infrared gas analyser.
Results
End-tidal sevoflurane concentrations were close to the predicted value of 2.6% at
9 minutes (2.53 ± 0.1% group S; 2.60 ± 0.26% group A) and 16 minutes (2.55 ± 0.30
group S; 2.52 ± 0.28% group A) but declined thereafter to reach 50% (group S) and
64% (group A) of the predicted value at 121 minutes. There was a constant trend towards
higher end-tidal sevoflurane concentrations in group A but the difference was not
statistically significant.
Conclusions
The square-root-of-time model leads to significantly lower alveolar concentrations
than expected, suggesting that the rate of sevoflurane uptake in dogs declines less
rapidly than predicted. The use of Amsorb tends to reduce the deviation from predicted
concentrations.
Clinical relevance
The model used in this study provided only an approximate guide to the volume of liquid
sevoflurane required. Consequently, the definitive dose schedule must be based on
measured anaesthetic concentrations and clinical monitoring.
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Veterinary Anaesthesia and AnalgesiaAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Vorteile der Rückatmung.in: Baum J Die Inhalationsanästhesie mit niedrigem Frischgasfluss. 3rd edn. Thieme, Stuttgart1998: 62-75 (1991)
- Uptake of enflurane and isoflurane during spontaneous and controlled ventilation.Anaesth Intens Care. 1992; 20: 191-195
- Nitrous oxide uptake during spontaneous and controlled ventilation.Anaesthesia. 1994; 49: 25-28
- Closed-circuit anesthesia with sevoflurane in humans.Anesthesiology. 1994; 80: 71-76
- Effects of low-flow sevoflurane anesthesia on renal function.Anesthesiology. 1997; 86: 1231-1237
- Pitfalls in using modern gas analysers for monitoring closed-system anaesthesia.Vet Anaesth Analg. 2001; 28 (Abstract).: 208-209
- Bioenergetics and growth. Reinhold, New York, USA.1945
- Quantitative study of Lowe's square-root-of-time method of closed system anaesthesia.Br J Anaesth. 1997; 79: 103-112
- Sevoflurane degradation to compound A in anaesthesia breathing systems.Br J Anaesth. 1996; 77: 537-543
- Understanding Anesthesia Equipment. 4th edn. Williams & Wilkins, Baltimore1999: 557-671
- Complexities overlooked: things may not be what they seem.Anesth Analg. 1997; 84: 239-240
- Uptake and distribution.in: Miller RD Anesthesia. 5th edn. Churchill Livingstone, Philadelphia, PA, USA2000: 74-95
- Nephrotoxicity of sevoflurane versus desflurane anesthesia in volunteers.Anesth Analg. 1997; 84: 160-168
- Circuit absorption of halothane, isoflurane, and sevoflurane.Anesth Analg. 1998; 86: 1070-1074
- Comparison of renal function following anesthesia with low-flow sevoflurane and isoflurane.J Clin Anesth. 1999; 11: 201-207
- Uptake of desflurane and isoflurane during closed-circuit anesthesia with spontaneous and controlled mechanical ventilation.Anesth Analg. 1997; 84: 413-418
- Sevoflurane pharmacokinetics: effects of cardiac output.Br J Anaesth. 1998; 81: 495-501
- Influence of the reference gas of paramagnetic oxygen analysers on nitrogen concentrations during closed-circuit anesthesia.J Clin Monit. 1998; 14: 381-384
- Compound A concentrations during low-flow sevoflurane anesthesia correlate directly with the concentrations of monovalent bases in carbon dioxide absorbents.Anesth Analg. 2000; 91: 434-439
- The effects of low-flow sevoflurane and isoflurane anesthesia on renal function in subjects with stable moderate renal insufficiency.Anesth Analg. 2001; 92: 650-655
- Comparison of MAC and the rate of rise of alveolar concentration of sevoflurane with halothane and isoflurane in the dog.Anesthesiology. 1988; 68: 435-437
- Biotransformation of sevoflurane.Anesth Analg. 1995; 81: S27-S38
- Long-duration low-flow sevoflurane and isoflurane effects on postoperative renal and hepatic function.Anesth Analg. 2001; 93: 1511-1520
- Comparison of Amsorb, sodalime and Baralyme degradation of volatile anesthetics and formation of carbon monoxide and compound A in swine in vivo.Anesthesiology. 2002; 96: 173-182
- Visceral losses of desflurane, isoflurane, and halothane in swine.Anesth Analg. 1991; 73: 209-212
- Uptake of anaesthetic gases and vapours.Anaesth Intens Care. 1994; 22: 363-373
- Uptake of inhalation anesthetics does not follow a power function.Anesthesiology. 1997; 87 (Abstract).: 345
- The Quantitative Practice of Anesthesia. 1st edn. Williams & Wilkins, Baltimore, MD, USA1981
- Nomogram for anaesthetic uptake.Anaesth Intens Care. 1994; 22: 374-375
- Influence of volatile anesthetics on left ventricular afterload in vivo.Anesthesiology. 1996; 85: 112-120
- Oxygen.in: Lumb AB Nunn's Applied Respiratory Physiology. 5th edn. Butterworth Heinemann, Oxford, UK2000: 249-305
- The effects of sevoflurane on serum creatinine and blood urea nitrogen concentration: a retrospective, twenty-two-center, comparative evaluation of renal function in adult surgical subjects.Anesth Analg. 2000; 90: 683-688
- Introduction to the quantitative technique of closed circuit anesthesia in dogs.Vet Surg. 1988; 17: 98-104
- Reaction of sevoflurane and its degradation products with soda lime.Anesthesiology. 1992; 77: 1155-1164
- Accumulation of methane, acetone, and nitrogen in the inspired gas during closed-circuit anesthesia.Anesth Analg. 1985; 64: 343-347
- Cardiorespiratory effects of low-flow and closed circuit inhalation anesthesia, using sevoflurane delivered with an in-circuit vaporizer and concentrations of compound A.Am J Vet Res. 1998; 59: 603-608
- Amsorb.Anesthesiology. 1999; 91: 1342-1348
- The effects of prolonged low-flow sevoflurane anesthesia on renal and hepatic function.Anesth Analg. 2000; 91: 1262-1268
- Closed-circuit liquid injection isoflurane anesthesia in the horse.Vet Surg. 1993; 22: 73-78
- Functional residual capacity and respiratory nitrogen excretion of dogs.J Appl Physiol. 1955; 8: 95-101
- Absorbents differ enormously in their capacity to produce compound A and carbon monoxide.Anesth Analg. 2000; 90: 1428-1435
- Inhalational anesthetics.in: Thurmon JC Tranquilli WJ Benson GJ Lumb and Jones' Veterinary Anesthesia. 3rd edn. Williams & Wilkins, Baltimore, MD, USA1996: 297-329
- Partition co-efficients for sevoflurane in human blood, saline and olive oil.Anesth Analg. 1987; 66: 654-657
- Repeated low-flow sevoflurane anesthesia: effects on hepatic and renal function in beagles.Masui. 1997; 46: 351-357
- Vaporization of isoflurane by liquid infusion.Anaesth Intens Care. 1994; 22: 380-382
- Predictive performance of a physiological model for enflurane closed-circuit anaesthesia: effects of continuous cardiac output measurements and age-related solubility data.Br J Anaesth. 2002; 88: 38-45
- Uptake of enflurane: a study of the variability between subjects.Br J Anaesth. 1983; 55: 595-601
- Pharmacokinetics of inhaled anaesthetics in a clinical setting: comparison of desflurane, isoflurane and sevoflurane.Br J Anaesth. 2000; 84: 443-449
- Solubility of I-653, sevoflurane, isoflurane, and halothane in human tissues.Anesth Analg. 1989; 69: 370-373
Article info
Publication history
Accepted:
June 17,
2002
Received:
April 22,
2002
Identification
Copyright
© 2005 Association of Veterinary Anaesthetists and American College of Veterinary Anesthesia and Analgesia. Published by Elsevier Inc. All rights reserved.
