Ostlund A, Linnarsson D
Department of Anesthesiology and Intensive Care, Karolinska Hospital, Stockholm, Sweden.
Acta Anaesthesiol Scand. 1998 Oct;42(9):1043-9. doi: 10.1111/j.1399-6576.1998.tb05374.x.
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.
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.
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.
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).
全身麻醉恢复期间，吸气阻力增加并伴有轻度气体麻醉很常见，但此前关于亚麻醉剂量气体麻醉期间吸气负荷的研究很少。
在16名健康受试者处于轻度亚麻醉剂量气体麻醉状态下，研究了呼吸驱动（中枢吸气活动，P0.1）和通气模式对-6 cm H₂O吸气阈值负荷的反应。一组（n = 9）吸入13%、26%和39%的氧化亚氮（N₂O）并以空气作为对照（N组）。另一组（n = 7）吸入0.1%、0.2%和0.3%的异氟烷并以空气作为对照（I组）。在适应负荷1分钟后进行测量。
无论是在无负荷呼吸期间还是在吸气阈值负荷期间，氧化亚氮和异氟烷对呼吸驱动和潮气量均无影响。在所有气体浓度下（包括0%对照），吸气阈值负荷均导致P0.1显著增加，N组增加了62%，I组增加了38%。与此同时，潮气量分别下降了11%和12%。与空气对照相比，吸入异氟烷期间终末呼气二氧化碳显著增加，分钟通气量下降，但这可能归因于对照情况下过度通气的正常化。
得出的结论是，在吸入亚麻醉剂量的N₂O（0.13 - 0.38 MAC）和异氟烷（0.09 - 0.26 MAC）期间，对负荷的稳态通气反应得以维持，表现为P0.1增加和潮气量下降。
