Inhalation sedation is a method used to help patients relax during various medical and dental procedures. Commonly known as “laughing gas,” this method involves breathing a specific gas mixture. It gently alleviates anxiety, allowing individuals to feel at ease while remaining responsive. Healthcare providers have used this technique since the mid-19th century, valuing its quick onset and rapid dissipation of effects.
The Sedation Experience
During inhalation sedation, a small mask is placed comfortably over the patient’s nose, through which a mixture of nitrous oxide and oxygen is delivered. Initially, 100% oxygen is established before nitrous oxide is gradually introduced. The gas mixture slows the nervous system, with effects noticeable within three to five minutes.
As the gas takes effect, patients commonly describe sensations like light-headedness, warmth, or a pleasant tingling in their arms and legs. Many experience a general sense of well-being, sometimes accompanied by mild euphoria or giggling, contributing to the “laughing gas” moniker. Despite these calming effects, patients remain fully conscious and can hear and respond to instructions from the clinician. This allows for continuous communication, ensuring comfort and cooperation.
The healthcare provider can adjust the level of sedation in real-time, increasing or decreasing nitrous oxide concentration to achieve optimal relaxation. This adaptability helps patients feel disconnected from anxiety, even while aware of the procedure.
Patient Suitability and Contraindications
Inhalation sedation is suitable for individuals with mild to moderate anxiety about medical or dental procedures. It also benefits those with an exaggerated gag reflex or children who find it challenging to remain still. This method is well-suited for shorter procedures requiring rapid onset and recovery.
However, certain conditions may make inhalation sedation unsuitable. Pregnant individuals, especially during the first trimester, are advised against its use due to concerns about vitamin B12 and folate metabolism. People with severe respiratory conditions, such as Chronic Obstructive Pulmonary Disease (COPD) or emphysema, should avoid nitrous oxide because the higher oxygen concentration can reduce their natural breathing drive. Individuals with severe psychiatric disorders, including schizophrenia or bipolar disorder, or a history of substance abuse, may not be suitable candidates, as nitrous oxide can induce dreaming or hallucinations.
Other considerations include pre-existing vitamin B12 deficiency, as nitrous oxide can inactivate an enzyme reliant on B12, potentially leading to megaloblastic anemia. The gas also diffuses rapidly into closed air spaces within the body, making it contraindicated for patients with conditions such as:
Pneumothorax
Middle ear blockages
Bowel obstructions
Recent eye surgeries involving intraocular gas bubbles (due to increased pressure risk)
The nasal mask can trigger claustrophobia in some patients. Also, its ability to support combustion means it should not be used during procedures involving heat or sparks, such as laser treatments or electro-cautery.
Post-Procedure Recovery
A key advantage of inhalation sedation is the swift reversal of its effects once the gas flow is discontinued. Due to its low solubility in body tissues, nitrous oxide is not significantly stored and is rapidly expelled through the lungs, typically within one to three minutes. To facilitate this rapid recovery and prevent “diffusion hypoxia,” clinicians administer 100% oxygen for several minutes after the nitrous oxide is turned off. This oxygen flush helps to quickly clear any remaining nitrous oxide from the lungs, ensuring that the patient’s blood oxygen levels remain stable.
This rapid elimination means patients generally feel alert and normal very quickly after the procedure concludes. A significant benefit of this quick recovery is that most individuals can safely drive home and promptly resume their regular daily activities without needing an escort. Some patients might experience minor, transient side effects like a brief headache or mild nausea, which usually resolve within a few minutes. Severe nausea and vomiting are rare, though reported to be more common in procedures exceeding two hours.