Inhalation sedation

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Quantiflex machine used to deliver oxygen and nitrous oxide gas for inhalation sedation. Quantiflex machine.jpg
Quantiflex machine used to deliver oxygen and nitrous oxide gas for inhalation sedation.

Inhalation sedation is a form of conscious sedation where an inhaled drug should:

Contents

  1. Depress the central nervous system (CNS) to an extent that surgeons can operate with minimal physiological and psychological stress to the patient
  2. Modify the patient's state of mind such that communication is maintained and the patient can respond to verbal command
  3. Carry a margin of safety wide enough to render the unintended loss of consciousness and loss of protective reflexes unlikely. [1]

Medical uses

The following are possible uses for conscious sedation "dental anxiety and phobia, a need for prolonged or traumatic dental procedures, medical conditions potentially aggravated by stress (such as ischaemic heart disease, hypertension, asthma and epilepsy), medical or behavioural conditions affecting a patient's ability to cooperate, special care requirements". [2]

Side effects

Complications from inhalation sedation are rare, and are those events that require intervention to correct adverse physiological responses. They include over-sedation, respiratory depression/apnoea, unconscious patient, airway obstruction, vomiting, idiosyncratic responses, delayed recovery, and failure of conscious sedation. [3]

Few absolute contraindications exist, however, "relative contraindications are important and can only be considered following a full assessment." [4] They include:

Patient assessment and selection

Nasal mask or hood Nasal hood.png
Nasal mask or hood

On a visit prior to the treatment session, the anesthesiologist makes a full assessment to determine the need for sedation and the technique most suited to the individual patient. [2] This consists of a detailed record of the patient's history and a thorough examination. A medical, dental, and social history covers the patient's age, state of health, social circumstances, drug history, and any special needs. This helps determine the sedation technique most appropriate for a positive outcome for each individual. [4] The examination takes into account the patient's general appearance, skin colour, pulse, blood pressure, and respiration rates. [4] Only patients in ASA classes I and II are normally suitable for sedation in the primary care dental setting. Patients in ASA class III or IV should be referred to an appropriate secondary care (i.e., hospital) establishment with critical care facilities. [4]

Contraindications

Inhalation sedation using nitrous oxide has a long history of safe use in both medicine and dentistry. It can therefore be used safely in most patients in the dental setting. [5] However, in some patients sedation with nitrous oxide would be unsuitable. Some examples are below.

Problems

Inhalation sedation with nitrous oxide/oxygen is a well recognised safe and effective technique. The desirable effect of the procedure is to relax the patient while maintaining verbal contact. Compared to other sedation agents, it causes minimal physiological stress to the patient and risk of loss of consciousness is less likely. However, problems can still arise. It is vital the dental staff are appropriately trained and qualified in dealing with complications and medical emergencies. Administering oxygen is of highest importance in an emergency situation. If patient is showing signs of oversedation, the concentration of nitrous oxide should be immediately reduced, and the oxygen concentration should be increased.[ citation needed ] All patients undergoing treatment under sedation should be continually assessed in the following:

Any deviation from the normal values should prompt the dental clinician to lighten the sedation.The dental clinician can recognise and deal with the following sedation related complications:

There are some downsides relating to the use of nitrous oxide. It can present as a potential hazard to the operator in charge of administering the gas. It has been shown that continual exposure to nitrous oxide can result in illnesses, such as haematological disorders and reproductive problems. Thus, active or passive scavenging is essential to remove nitrous oxide from the environment. Another disadvantage can be the risk of mouth breathing. Inhalation sedation requires the patient to breath through the nose, which can be especially difficult in very young children or patients with learning difficulties. Additionally, the drug cannot be used alone; it must be used alongside appropriate methods of behaviour management and local anaesthetic. Therefore, the degree of sedation can depend on the efficacy of behavioural techniques and psychological reassurance from the dentist. [6]

Equipment & safety features

Quantiflex flowmeter Quantiflex close-up.jpg
Quantiflex flowmeter

In the UK, machines used for the administration of inhalation sedation should follow the British Standards [8] and be well-maintained according to the manufacturer's guidance.

Equipment

Equipment used for inhalation sedation for dentistry include: [9]

  1. Gas cylinders
  2. Flowmeter
  3. Reservoir bag
  4. Conduction Tubing
  5. Breathing apparatus (Nasal hood or face mask)

Safety features

Oxygen fail safe mechanism is the most important safety feature of the equipment used in inhalation sedation. Nitrous oxide flow is only allowed via an opened valve when there is flow of oxygen to the system. In any circumstances when oxygen flow is less than 30%, nitrous oxide stops flowing. This prevents the potential delivery of 100% nitrous oxide and it becomes a standard on every sedation unit made today. [9]

Reservoir bag Reservoir bag close-up.jpg
Reservoir bag

All nasal hoods should have scavenging ability— provide fresh gas to the patient through one or two hoses while the extra hoses eliminate exhaled gas by the patient via a vacuum system. [9]

A pin index safety system prevents incorrectly fitting the two cylinders. [9] In addition, the cylinders are colour coded, which further reduces the risk of incorrect cylinder placement. [10]

A diameter index system is also in place to prevent incorrect linking of hoses and stems—the attachment couplings, hoses, and stems are different diameters. [9]

Pressure relief devices that dissipate contents of the cylinder to the atmosphere prevent explosion of cylinder due to over-filling. In an emergency, an oxygen flush or emergency oxygen system passes a high flow of high pressure oxygen direct from the source bypassing intermediate meters. [10]

Several alarm systems are used to indicate a depleting oxygen supply. Audible alarms are required in Europe and are recommended in the United States. [9]

History

"Laughing gas" was often used as entertainment in the early 1800s. Satire; 'Laughing Gas' after G. Cruikshank Wellcome M0009666.jpg
"Laughing gas" was often used as entertainment in the early 1800s.

Nitrous oxide was first discovered by Joseph Priestley in 1772. In 1795, Humphry Davy and surgeon J. B. Borlase experimented with nitrous oxide and the effects of its inhalation. Davy then published a book in 1799 hinting the possible role of nitrous oxide in achieving mild anaesthesia during surgical procedures. In 1844, Dr. Horace Wells carried out an experiment on himself where he had Professor Gardner Quincy Colton administer nitrous oxide to himself prior to a wisdom tooth extraction by Dr. John Riggs. Wells discovered that he was unaware of the procedure and experienced absolutely no pain during the procedure. [11]

In 1824, Henry Hill Hickman used carbon dioxide to achieve a state of "suspended animation" in animals; successfully diminishing pain during the surgical procedure. [11]

In 1831, chloroform was discovered by Justus von Liebig in Germany, Samuel Guthrie in New York and Eugène Soubeiran in France, all of whom worked independently. [11]

In 1842, a chemist in Rochester, William Edward Clarke provided Dr. Elijah Pope with ether prior to a tooth extraction of his patient. [12] In the same year, a doctor in Georgia, Dr. Crawford W. Long administered ether to John Venable for the removal of a neck tumour. [11]

Related Research Articles

Anesthesia is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia, paralysis, amnesia, and unconsciousness. An individual under the effects of anesthetic drugs is referred to as being anesthetized.

<span class="mw-page-title-main">Tracheal intubation</span> Placement of a tube into the trachea

Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic tube into the trachea (windpipe) to maintain an open airway or to serve as a conduit through which to administer certain drugs. It is frequently performed in critically injured, ill, or anesthetized patients to facilitate ventilation of the lungs, including mechanical ventilation, and to prevent the possibility of asphyxiation or airway obstruction.

Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure. Examples of drugs which can be used for sedation include isoflurane, diethyl ether, propofol, etomidate, ketamine, pentobarbital, lorazepam and midazolam.

<span class="mw-page-title-main">Positive airway pressure</span> Mechanical ventilation in which airway pressure is always above atmospheric pressure

Positive airway pressure (PAP) is a mode of respiratory ventilation used in the treatment of sleep apnea. PAP ventilation is also commonly used for those who are critically ill in hospital with respiratory failure, in newborn infants (neonates), and for the prevention and treatment of atelectasis in patients with difficulty taking deep breaths. In these patients, PAP ventilation can prevent the need for tracheal intubation, or allow earlier extubation. Sometimes patients with neuromuscular diseases use this variety of ventilation as well. CPAP is an acronym for "continuous positive airway pressure", which was developed by Dr. George Gregory and colleagues in the neonatal intensive care unit at the University of California, San Francisco. A variation of the PAP system was developed by Professor Colin Sullivan at Royal Prince Alfred Hospital in Sydney, Australia, in 1981.

<span class="mw-page-title-main">Inhalation</span> Flow of the respiratory current into an organism

Inhalation happens when air or other gases enter the lungs.

<span class="mw-page-title-main">Oxygen therapy</span> Use of oxygen as a medical treatment

Oxygen therapy, also known as supplemental oxygen, is the use of oxygen as medical treatment. Acute indications for therapy include hypoxemia, carbon monoxide toxicity and cluster headache. It may also be prophylactically given to maintain blood oxygen levels during the induction of anesthesia. Oxygen therapy is often useful in chronic hypoxemia caused by conditions such as severe COPD or cystic fibrosis. Oxygen can be delivered via nasal cannula or face mask, or via high pressure conditions such as in endotracheal intubation or hyperbaric chamber. It can also be given through bypassing the airway, such as in ECMO therapy.

<span class="mw-page-title-main">Anaesthetic machine</span> Medical device used to generate a fresh gas flow for anaesthesia

An anaesthetic machine or anesthesia machine is a medical device used to generate and mix a fresh gas flow of medical gases and inhalational anaesthetic agents for the purpose of inducing and maintaining anaesthesia.

<span class="mw-page-title-main">Respiratory arrest</span> Medical condition

Respiratory arrest is a sickness caused by apnea or respiratory dysfunction severe enough it will not sustain the body. Prolonged apnea refers to a patient who has stopped breathing for a long period of time. If the heart muscle contraction is intact, the condition is known as respiratory arrest. An abrupt stop of pulmonary gas exchange lasting for more than five minutes may permanently damage vital organs, especially the brain. Lack of oxygen to the brain causes loss of consciousness. Brain injury is likely if respiratory arrest goes untreated for more than three minutes, and death is almost certain if more than five minutes.

<span class="mw-page-title-main">Nitrous oxide (medication)</span> Gas used as anesthetic and for pain relief

Nitrous oxide, is an inhaled gas used as a pain medication and together with other medications for anesthesia. Common uses include during childbirth, following trauma, and as part of end-of-life care. Onset of effect is typically within half a minute, and the effect lasts for about a minute.

<span class="mw-page-title-main">Oxygen mask</span> Interface between the oxygen delivery system and the human user

An oxygen mask provides a method to transfer breathing oxygen gas from a storage tank to the lungs. Oxygen masks may cover only the nose and mouth or the entire face. They may be made of plastic, silicone, or rubber. In certain circumstances, oxygen may be delivered via a nasal cannula instead of a mask.

<span class="mw-page-title-main">Inhaler</span> Medical device

An inhaler is a medical device used for delivering medicines into the lungs through the work of a person's breathing. This allows medicines to be delivered to and absorbed in the lungs, which provides the ability for targeted medical treatment to this specific region of the body, as well as a reduction in the side effects of oral medications. There are a wide variety of inhalers, and they are commonly used to treat numerous medical conditions with asthma and chronic obstructive pulmonary disease (COPD) being among the most notable.

Hypopnea is overly shallow breathing or an abnormally low respiratory rate. Hypopnea is defined by some to be less severe than apnea, while other researchers have discovered hypopnea to have a "similar if not indistinguishable impact" on the negative outcomes of sleep breathing disorders. In sleep clinics, obstructive sleep apnea syndrome or obstructive sleep apnea–hypopnea syndrome is normally diagnosed based on the frequent presence of apneas and/or hypopneas rather than differentiating between the two phenomena. Hypopnea is typically defined by a decreased amount of air movement into the lungs and can cause oxygen levels in the blood to drop. It commonly is due to partial obstruction of the upper airway.

Dental anesthesia is the application of anesthesia to dentistry. It includes local anesthetics, sedation, and general anesthesia.

<span class="mw-page-title-main">Dental fear</span> Medical condition

Dental fear, or dentophobia, is a normal emotional reaction to one or more specific threatening stimuli in the dental situation. However, dental anxiety is indicative of a state of apprehension that something dreadful is going to happen in relation to dental treatment, and it is usually coupled with a sense of losing control. Similarly, dental phobia denotes a severe type of dental anxiety, and is characterised by marked and persistent anxiety in relation to either clearly discernible situations or objects or to the dental setting in general. The term ‘dental fear and anxiety’ (DFA) is often used to refer to strong negative feelings associated with dental treatment among children, adolescents and adults, whether or not the criteria for a diagnosis of dental phobia are met. Dental phobia can include fear of dental procedures, dental environment or setting, fear of dental instruments or fear of the dentist as a person. People with dental phobia often avoid the dentist and neglect oral health, which may lead to painful dental problems and ultimately force a visit to the dentist. The emergency nature of this appointment may serve to worsen the phobia. This phenomenon may also be called the cycle of dental fear. Dental anxiety typically starts in childhood. There is the potential for this to place strains on relationships and negatively impact on employment.

Procedural sedation and analgesia (PSA) is a technique in which a sedating/dissociative medication is given, usually along with an analgesic medication, in order to perform non-surgical procedures on a patient. The overall goal is to induce a decreased level of consciousness while maintaining the patient's ability to breathe on their own. Airway protective reflexes are not compromised by this process and therefore endotracheal intubation is not required. PSA is commonly used in the emergency department, in addition to the operating room.

<span class="mw-page-title-main">Twilight anesthesia</span> Anesthetic technique

Twilight anesthesia is an anesthetic technique where a mild dose of sedation is applied to induce anxiolysis, hypnosis, and anterograde amnesia. The patient is not unconscious, but sedated. During surgery or other medical procedures, the patient is under what is known as a "twilight state", where the patient is relaxed and "sleepy", able to follow simple directions by the doctor, and is responsive. Generally, twilight anesthesia causes the patient to forget the surgery and the time right after. It is used for a variety of surgical procedures and for various reasons. Just like regular anesthesia, twilight anesthesia is designed to help a patient feel more comfortable and to minimize pain associated with the procedure being performed and to allow the medical practitioner to practice without interruptions.

Oral sedation dentistry is a medical procedure involving the administration of sedative drugs via an oral route, generally to facilitate a dental procedure and reduce patients anxiety related to the experience. Oral sedation is one of the available methods of conscious sedation dentistry, along with inhalation sedation and conscious intravenous sedation. Benzodiazepines are commonly used, specifically triazolam. Triazolam is commonly selected for its rapid onset and limited duration of effect. An initial dose is usually taken approximately one hour before the dental appointment. Treatment may include additional dosing on the night proceeding the procedure, to mitigate anxiety-related insomnia. The procedure is generally recognized as safe, with the effective dosages being below levels sufficient to impair breathing.

A relative analgesia machine is used by dentists to induce inhalation sedation in their patients. It delivers a mixture of nitrous oxide and oxygen. A relative analgesia machine is simpler than an anaesthetic machine, as it does not feature the additional medical ventilator and anaesthetic vaporiser, which are only needed for administration of general anesthetics. Instead the relative analgesia machine is designed for the light form of anaesthesia with nitrous oxide, where the patient is less sensitive to pain but remains fully conscious.

<span class="mw-page-title-main">Heated humidified high-flow therapy</span> Respiratory support method

Heated humidified high-flow (HHHF) therapy, often also high flow nasal cannula(e) (HFNC) or high flow nasal oxygen (HFNO), is a type of respiratory support method that delivers a high flow (liters per minute) of medical gas to a patient through an interface (nasal cannulae) intended to create a wash-out of the upper airway. The applied gas is heated to best match human body temperature (37 °C) and humidified targeting ideal body saturation vapor pressure. It is used in acute and chronic breathing problems, and is a suitable choice for treatment of patients with severe or critical COVID-19.

<span class="mw-page-title-main">Advanced airway management</span>

Advanced airway management is the subset of airway management that involves advanced training, skill, and invasiveness. It encompasses various techniques performed to create an open or patent airway – a clear path between a patient's lungs and the outside world.

References

  1. M., Girdler, N. (2009). Clinical sedation in dentistry. Hill, C. M., Wilson, K. E. (Katherine Elizabeth), 1963-. Chichester, U.K.: Wiley-Blackwell. ISBN   9781444312201. OCLC   437132993.
  2. 1 2 "Conscious Sedation in Dentistry" (PDF). Scottish Dental Clinical Effectiveness Programme. June 2017.
  3. "Standards for Conscious Sedation in the Provision of Dental Care: Report of the Intercollegiate Advisory Committee for Sedation in Dentistry (IACSD)". 22 April 2015. Retrieved 30 Dec 2017.
  4. 1 2 3 4 "BDA Advice - Conscious Sedation" (PDF). baos.co.uk. November 2011. Retrieved 30 December 2017.
  5. 1 2 3 4 5 6 7 Becker, Daniel E.; Rosenberg, Morton (2008). "Nitrous oxide and the inhalation anesthetics". Anesthesia Progress. 55 (4): 124–130, quiz 131–132. doi:10.2344/0003-3006-55.4.124. ISSN   0003-3006. PMC   2614651 . PMID   19108597.
  6. 1 2 Girdler, N. M. (2009). Clinical sedation in dentistry. Hill, C. M., Wilson, K. E. (Katherine Elizabeth), 1963-. Chichester, U.K.: Wiley-Blackwell. ISBN   978-1-4051-8069-6. OCLC   230187665.
  7. 1 2 3 4 Girdler, N. M. (2017-09-20). Conscious sedation for dentistry. Hill, C. M.,, Wilson, K. E. (Katherine Elizabeth), 1963- (Second ed.). Hoboken, NJ, USA. ISBN   978-1-119-27448-3. OCLC   980346465.
  8. "Anaesthetic and analgesic machines". British Standard Institution. BS4273. 1997.
  9. 1 2 3 4 5 6 S.Clark, L.Brunick, Morris, Ann (2015). Handbook of Nitrous Oxide and Oxygen sedation. St Louis, Missouri: Elsevier Mosby. ISBN   978-1-4557-4547-0.
  10. 1 2 Subrahmanyam, M; Mohan, S (2013). "Safety Features in Anaesthesia Machine". Indian Journal of Anaesthesia. 57 (5): 472–480. doi:10.4103/0019-5049.120143. ISSN   0019-5049. PMC   3821264 . PMID   24249880.
  11. 1 2 3 4 Malamed, Stanley F. (2017-05-03). Sedation : a guide to patient management. Preceded by: Malamed, Stanley F., 1944- (Sixth ed.). St. Louis, Missouri. ISBN   9780323400527. OCLC   993625331.
  12. López-Valverde, A.; Montero, J.; Albaladejo, A.; Diego, R. Gómez de (2010-10-12). "The Discovery of Surgical Anesthesia". Journal of Dental Research. 90 (1): 31–34. doi:10.1177/0022034510385239. PMID   20940364. S2CID   32937909.