Nitrous oxide

Nitrous oxide has a narcotic analgesic effect.

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Indications Nitrous oxide

It is used in complex anesthesia procedures through inhalation (a special device is used) – together with other pain-relieving drugs, as well as opiates and muscle relaxants.

It is used for systemic anesthesia, where deep anesthesia and muscle relaxation are not required (e.g. general surgical procedures, gynecological or dental operations, and analgesia during childbirth).

It is prescribed to potentiate the anaesthetic analgesic effect of other anaesthetics (for example, therapeutic analgesic anesthesia after the end of surgery), and also in cases of shock of traumatic origin (for the purpose of prevention).

The medication is also used for various types of pain, including acute coronary insufficiency, exacerbated pancreatitis, or myocardial infarction.

It can be prescribed for analgesia during various medical procedures or when there is a need to turn off consciousness.

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Release form

The medicinal substance is released in 10-liter cylinders.

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Pharmacodynamics

The drug is used for inhalations to put the patient into anesthesia. It non-specifically affects the activity of neural membranes and suppresses the transmission of impulses from them to the central nervous system, while also changing the cortical-subcortical connections.

Nitrous oxide has a powerful analgesic effect. In small doses, the drug can lead to the development of mild drowsiness and a feeling of intoxication.

After inhalation, the anesthetic phase develops after a few minutes (if the gas mixture contains at least 80% nitrous oxide, and another 20% of the portion is oxygen). At first, a short (approximately 6-8 minutes), but quite noticeable phase of excitation is noted, and after this, the first stage of entering surgical anesthesia develops.

General anesthesia is maintained at nitrous oxide levels of 40-50%, and correspondingly with an increased oxygen content. It should be taken into account that in this case, sufficient relaxation of the skeletal muscles does not develop, which is why, in order to obtain the necessary therapeutic effect, nitrous oxide must be combined with other muscle relaxants, as well as with inhalation substances.

The patient awakens 3-5 minutes after the gas supply is stopped. An increase in the heart rate and narrowing of peripheral vessels are noted. An increase in ICP values and suppression of respiratory activity may also occur.

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Pharmacokinetics

The drug penetrates the lungs and then moves into the bloodstream. The substance remains in the plasma in a dissolved form, not subject to metabolic processes.

Complete excretion of the unchanged element occurs through the lungs after 10-15 minutes. A small portion of the substance is also excreted through the epidermis. The half-life is about 5-6 minutes.

The drug passes well through the blood-brain barrier, and also through the placenta.

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Dosing and administration

The medication is administered by inhalation: simultaneously with oxygen, as well as other substances for inhalation anesthesia. It is administered using special devices for gas anesthesia. At first, the mixture should include 70-80% nitrous oxide and 20-30% oxygen.

To eliminate pain or as a preventive measure, therapeutic anesthesia is performed, which contains dinitrogen oxide (the proportion is about 40-75%).

To quickly obtain the required depth of systemic anesthesia (induction), dinitrogen oxide is used in a proportion of 70-75%, and to maintain this state, 40-50% is required. If necessary, components such as ether, barbiturates or fluorothane can be included in the mixture. To avoid the occurrence of diffuse hypoxia after stopping the supply of nitrous oxide, it is necessary to continue to supply oxygen for another 4-5 minutes.

To eliminate pain during labor, an intermittent autoanalgesia method is used, when nitrous oxide is administered in a concentration of 40-75%, as well as oxygen. The woman in labor should inhale this substance at the moment when contractions begin, and exhale at their peak or after their end.

If there is a need to turn off consciousness during medical procedures, inhalations containing 25-50% oxygen are performed.

For children, portions are selected individually. Inhalations containing at least 30% oxygen are allowed, and after their completion, oxygen must be supplied for another 5 minutes to prevent the development of hypoxia.

To reduce increased emotional arousal, as well as vomiting with nausea and to enhance the drug effect, premedication should be performed in the form of intramuscular injections of a 0.5% solution of the substance diazepam (1-2 ml or 5-10 mg) or a 0.25% solution of the drug droperidol (2-3 ml or 5-7.5 mg).

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Use Nitrous oxide during pregnancy

Nitrous oxide inhalations are allowed to be used for analgesia during childbirth, but its prolonged use can lead to miscarriage or negatively affect the subsequent development of the child. If necessary, the drug is allowed to be used in small concentrations, in which the proportions to oxygen are 1:1. Use should be short-term - a maximum of 2-3 inhalations of the substance.

It is completely forbidden to use the medicine during lactation. If such inhalation is required, breastfeeding should be stopped for this period.

Contraindications

Main contraindications:

• presence of hypersensitivity to nitrogen oxides;
• hypoxia;
• various pathologies in the nervous system;
• alcohol intoxication or chronic alcoholism, because the use of drugs can lead to the appearance of hallucinations or a feeling of excitement.

Caution in using the drug is necessary in cases of TBI, increased intracranial pressure (also if present in the anamnesis), or in cases of intracranial tumors detected during diagnosis.

Side effects Nitrous oxide

Taking into account the phase of anesthesia, various negative manifestations may develop:

• at the stage of induction of anesthesia: bradycardia, supraventricular arrhythmia, or circulatory failure may develop;
• at the exit stage: development of diffuse hypoxia, and in addition to this, post-anesthetic delirium, against the background of which hallucinations appear and a feeling of confusion, anxiety, nervousness and agitation (including prolonged agitation) is noted;
• prolonged use: vomiting or nausea and drowsiness (more than 2 days) may occur, and in addition, anemia, respiratory depression, bone marrow dysfunction (pancytopenia or leukopenia) and polyneuropathy may develop. Postoperative chills and hyperthermic crisis may also occur.

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Overdose

Signs of poisoning include such pronounced disorders of the cardiovascular system: arrhythmia of various origins, suppression of respiratory activity, bradycardia, decreased blood pressure, and the occurrence of delirium and acute hypoxia.

To eliminate these violations, the following procedures should be carried out (taking into account the condition of the victim):

• to treat bradycardia, atropine must be administered in doses of 0.3-0.6 mg;
• in case of arrhythmia, it is necessary to correct the blood gas levels;
• if blood pressure drops or there is circulatory failure, the patient should be given plasma or plasma-substituting substances, and in addition, the depth of general anesthesia should be reduced or stopped;
• in case of a hyperthermic crisis, it is necessary to stop inhalation, increase oxygen supply, and in addition to this, administer an antipyretic to the patient and eliminate water-electrolyte imbalance disorders together with metabolic acidosis. Also, if necessary, dantrolene is used (intravenously through a drip, in a dose of 1 mg/kg; the total maximum permissible dosage is 10 mg/kg);
• to prevent recurrence of the crisis for 1-3 days after the surgical procedure, dantrolene should be administered intravenously or taken orally (the recommended dosage is 4-8 mg/kg/day; the dose is divided into 4 doses). If respiratory activity is suppressed or pulmonary ventilation is inadequate after the end of the operation, it is necessary to reduce the dose of the anesthetic (if it is still used) and ensure air flow through the respiratory tract (or connect the patient to a ventilator);
• In case of delirium, the patient should be given a small dose of opiate after he has recovered from general anesthesia.

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Interactions with other drugs

An increase in the effect of the drug is noted when combined with opiates, neuroleptics, inhalation anesthetics, tranquilizers and antihistamines.

Combination with atropine increases the likelihood of developing bradycardia, which cannot be stopped; combination with amiodarone increases the risk of lowering blood pressure; combination with xanthines increases the likelihood of arrhythmia.

Potentiation of the effect on the cardiovascular system (reduction in heart rate values, as well as cardiac output) occurs with simultaneous administration with fentanyl and its derivatives.

When combined with nitrous oxide, there is a potentiation of the effect of such antihypertensive agents as ganglionic blockers with diazoxide, diuretics and anticoagulants (this includes derivatives of indandione and coumarin), as well as drugs that can suppress the function of the central nervous system and the activity of the respiratory centers.

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Storage conditions

It is recommended to store nitrous oxide in a place closed to small children. The temperature indicator should not exceed 25°C.

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Shelf life

Nitrous oxide is permitted to be used within 5 years from the date of manufacture of the drug.

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Analogues

Analogues of the substance are the drugs Stikoxidal and Dinitrogen Oxide.

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