Abstract | BACKGROUND: Increased inspiratory resistance in combination with mild gas narcosis is common during recovery after a general anesthesia, but there are only few previous studies on inspiratory loading during subanesthetic gas narcosis. METHODS: Responses of respiratory drive (central inspiratory activity, P0.1) and ventilatory pattern to an inspiratory threshold load of -6 cm H2O were studied in 16 healthy subjects during mild subanesthetic gas narcosis. One group (n = 9) was exposed to 13, 26 and 39% nitrous oxide (N2O) and air control (Group N). Another group (n = 7) was exposed to 0.1, 0.2 and 0.3% isoflurane and air control (Group I). Measurements were done after 1 min adaptation to the load. RESULTS:
Nitrous oxide and isoflurane had no effect on respiratory drive and VT either during unloaded breathing or during inspiratory threshold loading. Across all gas concentrations (including 0% control), inspiratory threshold loading resulted in significant P0.1 increases, amounting to 62% in group N and 38% in group I. At the same time VT decreased by 11 and 12%, respectively. A significantly increased end-expired CO2 and decreased minute volume compared to air control was found during isoflurane inhalation but could be ascribed to normalization of the hyperventilation in the control situation. CONCLUSIONS: It is concluded that the steady-state ventilatory responses to loading, consisting of increased P0.1 and decreased VT, are maintained during inhalation of subanesthetic doses of N2O (0.13-0.38 MAC) and isoflurane (0.09-0.26 MAC).
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Authors | A Ostlund, D Linnarsson |
Journal | Acta anaesthesiologica Scandinavica
(Acta Anaesthesiol Scand)
Vol. 42
Issue 9
Pg. 1043-9
(Oct 1998)
ISSN: 0001-5172 [Print] England |
PMID | 9809086
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Anesthetics, Inhalation
- Isoflurane
- Nitrous Oxide
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Topics |
- Adult
- Anesthetics, Inhalation
(pharmacology)
- Female
- Humans
- Isoflurane
(pharmacology)
- Male
- Nitrous Oxide
(pharmacology)
- Respiration
(drug effects)
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