Medicinal nitrous oxide has well-known and well-documented dose-dependent analgesic and mild anesthetic effects with a MACawake of about 60 vol.% and a MACincision of about 110 vol.%. Nitrous oxide is not sufficiently strong to create general anesthesia as a sole agent. The interaction when combined with inhaled or intravenous anesthetics is more or less directly additive. It can also be combined with all clinically used hypnotics, analgesics and anesthetics. Apart from its analgesic/anesthetic properties, medicinal nitrous oxide exhibits only very minor effects on autonomic functions such as respiration and circulation. Spontaneous breathing is relatively better preserved when anesthesia is created by the combination of medicinal nitrous oxide and any of the commonly used inhaled anesthetics when compared with anesthesia induced by the potent inhaled anesthetic alone. The cardiovascular variables are also less affected.
The rapid “wash-in” (uptake) and “wash-out” (fast elimination) of medicinal nitrous oxide is well known. Because of this rapid elimination and well-maintained spontaneous respiration, emergence has been shown to be faster in many studies where a modern inhaled halogenated anesthetic has been combined with medicinal nitrous oxide than when that has been used alone.
Medicinal nitrous oxide is relatively inexpensive and certainly far more so than most other commonly-used anesthetics/analgesics.
Taking its clinical features, rapid on-set of action, minimal cardio-respiratory effects and rapid off-set, emergence into account as well as its low cost, medicinal nitrous oxide is an interesting cost-effective choice in modern anesthesia. Improving spontaneous respiration during surgical laryngeal mask anesthetic procedures (lasting an ever-increasing number of days) shortens emergence and brings early recovery, facilitating a rapid patient turnover in the operating theatre.
A long and highly extensive record of medicinal nitrous oxide in clinical use is also worthy of consideration. The contraindications for patients for whom the use of nitrous oxide could cause side effects are well recognized and easily identified. There is scarcely any other drug in use today that has been used so widely and so safely with such a vast number of patients.