Introduction
Intravenous sedation is anesthesia administered intravenously to patients before a dental procedure. Intravenous sedation, also known as conscious sedation, monitored anesthesia care (MAC), or twilight sleep, is a drug-induced depression of consciousness. Patients react intentionally to verbal commands, alone or in conjunction with light tactile stimulation. Furthermore, initiatives are needed to keep a patent airway, whereas spontaneous ventilation is sufficient. All conscious sedation service providers are accountable for ensuring that the environment in which care is provided is safe for patients. Intravenous conscious sedation induces a state and sensation of deep relaxation to disarm and comfort the patient and allow them to be unconcerned about what is happening.
The use of IVS has many benefits but also some risks, like depression of the respiratory and cardiovascular system, and pulmonary aspiration, during dental procedures under conscious sedation. As a result, clinical and instrumental monitoring must be used for the patient's medical condition and clinical setting, and the anesthetist conducting the sedation must be able to recognize adverse events and handle them safely and effectively.
What Are the Benefits of Intravenous Sedation?
There are numerous advantages to using IV sedation during plastic surgery and other procedures, including:
-
Rapid action.
-
Quick recovery.
-
Adjustment of the dose.
-
Less variation in vital signs.
-
There are fewer side effects.
-
There are fewer risks than with general anesthesia.
-
Cooperation ability of the patient.
-
Using a breathing tube as little as possible.
What Are the Risks of Intravenous Sedation?
Every type of anesthesia involves some amount of risk. Risks associated with IV sedation include:
-
Oversedation.
-
Headache.
-
Nausea.
-
Drowsiness.
-
Low motivation to breathe.
-
Compromise in respiratory function (needing a breathing tube).
-
Pneumonia due to aspiration (food or drink gets breathed into the airways or lungs).
-
Pain intensity has increased.
What Are the Intravenous Sedatives Currently Used for Dental Procedures?
Midazolam
-
Midazolam is a benzodiazepine derivative that is commonly used in dental sedatives. It works by activating the gamma-aminobutyric acid (GABA)-A receptor complex and increasing GABA-mediated chloride currents, resulting in neuron hyperpolarization and decreased excitability.
-
It reduces anxiety while causing little respiratory depression or cardiovascular instability. Midazolam has favorable anterograde amnesic properties, which is one of its characteristics.
-
Midazolam has a quick onset of action, with the peak effect occurring within two to three minutes of administration. Midazolam spreads rapidly after intravenous injection, with a distribution half-life of six to 15 minutes due to the rapid uptake of tissues.
-
Objective neurological tests returned to baseline 1.5 hours after intravenous administration. The elimination half-life ranged between 1.7 and 3.5 hours. Typically, the pharmacological duration of effect is one to two hours.
-
Following intravenous administration of Midazolam, paradoxical excitements occur. Hallucinations, disorientation, unmanageable crying or verbalization, anxiety, restlessness, involuntary movement, self-harm, and violent behavior are all possible reactions.
-
These reactions typically occur within five minutes of intravenous injection and are unlikely to resolve independently. Rapid tranquillization is required in this situation.
-
Additional Midazolam administration is ineffective and results in slow awakening. Low doses of Ketamine (0.5 milligrams per kilogram), Propofol, Physostigmine, Haloperidol, and Flumazenil (0.3 to 0.5 milligrams) are effective.
-
Midazolam is the sole benzodiazepine accepted to be used in neonates. The half-life is significantly prolonged for 6 to 12 hours. Following bolus administration, neonates have been known to develop severe hypotension.
-
Midazolam 0.5 to 1 milligram (0.01 to 0.1 milligram per kilogram for pediatric patients) over two minutes can be given repetitively for sedation. The sedative effect should be assessed two to five minutes after adjusting each dose.
-
No single dose should be more than 2.5 milligrams. A dose of more than five milligrams is normally not required to achieve the desired level of sedation.
Propofol
-
Propofol is a widely used sedative agent for intravenous sedation during dental treatment. Propofol functions by enabling inhibitory neurotransmission mediated by binding GABA-A receptors and enhancing GABA's allosteric affinity for the GABA-A receptor.
-
Prior injection of Lidocaine (0.5 milligrams per kilogram) or mixing Lidocaine with Propofol (two ml of one percent Lidocaine in eighteen ml Propofol) or using larger catheters installed in larger veins can decrease pain.
-
Propofol formulation can promote bacterial growth and should be administered within six hours of opening the ampule. Propofol's peak time of effect is 90 to 100 seconds after intravenous administration. The elimination half-life is four to seven hours, and the distribution half-life is two to eight minutes.
-
As a result, even after prolonged infusion, recovery from Propofol is rapid, making it an excellent agent for outpatient anesthesia. Due to the limited distribution volume, a lower dose is preferred in elderly patients.
-
A decrease in blood pressure is one of the most common side effects of Propofol sedation. It suppresses the hypoxic ventilation drive, resulting in airway obstruction and apnea, and is widely recognized as the best intravenous sedative for children.
-
Propofol administration could rapidly result in unintended deep sedation because of its limited therapeutic range and the vulnerability of children to the sedative effects, even after a small increase in dosages.
Ketamine
-
Ketamine induces dissociative anesthesia or sedation based on the dosage and mode of administration. Sedation is distinguished by profound analgesia, amnesia, catalepsy, preservation of protective airway reflexes, spontaneous respirations, and cardiopulmonary stability.
-
Ketamine onset of action and peak plasma concentration takes approximately one minute after intravenous administration. The elimination half-life is two to three hours, and the distribution half-life is ten to fifteen minutes.
-
Ketamine is highly lipid-soluble, with only 12 percent bound to proteins, allowing it to cross the blood-brain barrier quickly. Sedation lasts for five to ten minutes when injected intravenously and depends on the dose. As a result, Ketamine is better suited for sedation during brief procedures.
-
When Ketamine is administered, it causes mild cardiovascular stimulation in comparison to other sedatives that may have a depressive effect. Ketamine raises the heart rate, cardiac output, and blood pressure, and it should not be employed in patients with hypertension or at risk of cerebrovascular accidents or ischemic heart disease.
-
It is the only sedative agent that can preserve the functional residual capacity of the lungs during sedation, lowering the risk of intra-operative hypoxemia. Ketamine can treat asthmatic patients since it causes bronchodilation while not causing histamine release.
-
Moreover, Ketamine can cause salivary and trachea-bronchial secretions, and laryngospasms have been identified when high doses of Ketamine were administered to children younger than three months of age.
Dexmedetomidine
-
Dexmedetomidine is a highly selective-2 adrenoceptor agonist with a high selectivity for the-2 receptor over the-1 receptor. It causes anxiolysis and sedation through locus ceruleus receptors, analgesia through spinal cord receptors, and attenuation of the stress response with no considerable respiratory depression.
-
Activating these receptors in the central nervous system inhibits sympathetic activity, resulting in a decrease in blood pressure and heart rate and decreased arousal, sedation, and anxiolysis. It induces a distinct sleep pattern similar to normal physiological sleep, which actually results in easy arousal even from verbal stimuli.
-
Dexmedetomidine pharmacokinetics are unaffected by impairment of renal function (creatinine clearance 30 ml per minute) or age. Dexmedetomidine has an elimination half-life of two to three hours, with a context-sensitive half-life varying from four minutes after a ten-minute infusion to 250 minutes after an eight-hour infusion.
Conclusion: Administering conscious sedation should be capable of handling deep sedation and the risks associated with sedation. Moreover, the dentist must take care of the patient until he fulfills the discharge criteria and is sent home from the clinic. Single drugs are usually easier to titrate to achieve the desired result and are safer than the successive administration of two or more drugs. As a result, continuous intravenous administration of various sedative drugs should be avoided in intravenous sedation for conscious sedation.
