Larger tidal volume increases sevoflurane uptake in blood: a randomized clinical study

• Published in: Acta anaesthesiologica Scandinavica Vol. 54; no. 9; pp. 1111 - 1116
• Main Authors: ENEKVIST, B., Bodelsson, M., STURESSON, L. W., JOHANSSON, A.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2010; Blackwell
• Subjects: Adult; Aged; Aged, 80 and over; Anestesi och intensivvård; Anesthesia; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Anesthesiology and Intensive Care; Anesthetics, Inhalation - blood; Biological and medical sciences; Clinical Medicine; Female; Functional Residual Capacity; Humans; Klinisk medicin; Male; Medical and Health Sciences; Medical sciences; Medicin och hälsovetenskap; Methyl Ethers - blood; Middle Aged; Positive-Pressure Respiration; Prospective Studies; Tidal Volume; Volatile compound; Sevoflurane; General anesthetic; Tidal volume; Anesthesia; Uptake; Halogen Organic compounds
• ISSN: 0001-5172; 1399-6576
• DOI: 10.1111/j.1399-6576.2010.02291.x

Background: The rate of uptake of volatile anesthetics is dependent on alveolar concentration and ventilation, blood solubility and cardiac output. We wanted to determine whether increased tidal volume (VT), with unchanged end‐tidal carbon dioxide partial pressure (PETCO2), could affect the arterial concentration of sevoflurane. Methods: Prospective, randomized, clinical study. ASA physical status 2 and II patients scheduled for elective surgery of the lower abdomen were randomly assigned to one of the two groups with 10 patients in each: one group with normal VT (NVT) and one group with increased VT (IVT) achieved by increasing the inspired plateau pressure 0.04 cmH2O/kg above the initial plateau pressure. A corrugated tube added extra apparatus dead space to maintain PETCO2 at 4.5 kPa. The respiratory rate was set at 15 min−1, and sevoflurane was delivered to the fresh gas by a vaporizer set at 3%. Arterial sevoflurane tensions (Pasevo), Fisevo, PETsevo, PETCO2, PaCO2, VT and airway pressure were measured. Results: The two groups of patients were similar with regard to gender, age, weight, height and body mass index. The mean PETsevo did not differ between the groups. Throughout the observation time, arterial sevoflurane tension (mean±SE) was significantly higher in the IVT group compared with the NVT group, e.g. 1.9±0.23 vs. 1.6±0.25 kPa after 60 min of anesthesia (P<0.05). Conclusion: Ventilation with larger tidal volumes with isocapnia maintained with added dead‐space volume increases the tension of sevoflurane in arterial blood.