Performing a painless procedure is one of the key factors for establishing a good rapport with the patient and achieving patient co-operation in order to complete the procedure efficiently. In dentistry, most of the times it can be achieved with the help of local anaesthesia. But in cases where there is a complete lack of patient co-operation or the systemic background of the patient is such that local anesthesia cannot suffice, the use of sedation or general anesthesia may be warranted depending on the compliance of the patient and the type of procedure to be performed.
It is estimated that around 50 million people have dental fear, anxieties and phobias about visiting the dentist. This can prevent them from getting routine care and lead to more complex problems which requires more extensive work. By using means like sedation we can ensure that the patient receives all the required dental treatments while helping them remain calm and relaxed.
Definitions
1. Conscious sedation :
A minimally depressed level of consciousness, that retains the patient’s ability to maintain an airway independently and respond appropriately to physical stimulation and verbal command.
2. Deep Sedation :
A controlled state of depressed consciousness and reflexes, including inability to respond purposefully to a verbal command.
3. General Anesthesia :
A controlled state of unconsciousness, accompanied by partial or complete loss of protective reflexes, including inability to maintain an airway independently and respond purposefully to physical command and verbal stimuli.
Differences between general anesthesia and sedation
While both sedation and general anesthesia are forms of anesthesia and sedation is a component of general anesthesia, they are different in several respects.
Patients under general anesthesia have a complete loss of consciousness. This means that the patient will not feel, hear or remember anything. In contrast, a state of somewhere being very sleepy, being relaxed in consciousness and yet not unconscious, characterizes sedation. Moreover patients maintain their natural physiological reflexes and are capable of breathing on their own.
Cardiovascular function is usually unaffected or maintained throughout various stages of sedation while it is usually impaired in general anesthesia and careful monitoring is necessary.
Generally no extensive investigations are required before sedation and there is no need of premedicating the patient. While General anesthesia requires all basic investigations as well as pre-medication.
NPO is not required in sedation while it is strictly mandatory for general anesthesia. NPO means patient should be instructed to fast or to have nothing by mouth, a few hours before anesthesia.
Nonetheless, the recovery period from sedation is typically quicker than with general anesthesia.
Drugs used in Sedation/General anesthesia
I. Inhalation
A. Nitrous oxide
Can be used for mild to moderate levels of anxiety, for brief procedures. It has rapid onset and early recovery.
Cannot be used in claustrophobic patients and in respiratory tract infections.
B. Desflurane
C. Sevoflurane etc.
II. Oral ( various combinations are used)
It has got better acceptability and ease of operation with less incidence of ARD ( Acute respiratory distress)
A. Hydroxyzine
Mild sedative with antiemetic and anticholinergic activities as well.
Better used in combinations with other drugs.
B. Promethazine
Used in mild levels of anxiety.
Better used in combinations with other drugs.
C. Chloral hydrate
It has a long working time with wide range of actions, so used for all levels of anxiety.
It is not recommended in children below 6 yrs of age.
D. Diazepam
Safe for use in children below the age of 6 years.
Multiple dosages required.
E. Meperidine
F. Chlorpromazine. Etc.
III. Intramuscular - rapid onset of action.
A. Ketamine
Is a potent analgesic with potential of oral use but the safety of oral use is not yet established.
B. Midazolam
Possesses hypotonic, anticonvulsant and muscle relaxant properties along with antegrade amnesic and anxiolytic properties.
Rapid onset of action but can be used mainly for short procedures.
IV. Intravenous -
A. Midazolam
Most rapid onset of action.
Permits titration and is easily reversible.
Requires extensive armamentarium training and precautions to be administered in patients with significant thyroid and hepatic diseases.
V. Rectal, subcutaneous or submucosal routes are rarely used.
Indications in dentistry
1. Patients with certain physical, mental or medically compromising conditions.
2. Patients wherein local anesthesia is not effective or patient is allergic to it.
3. Patients who have sustained extensive orofacial trauma.
4. Fearful, uncooperative and anxious patient with no expectation that behaviour will improve.
Contraindications
1. Chronic obstructive pulmonary disease
2. Pregnancy
3. Myasthenia
4. Epilepsy
Anesthetic emergencies in dentistry
Serious anesthetic emergencies are infrequent but do occur. Being prepared for emergencies is very important for ameliorating the impact of these events as despite being rare, they have a great impact. The practitioner should have thorough knowledge of handling emergencies including practising emergency skills.
COMMON RESPIRATORY EMERGENCIES
1. LARYNGOSPASMS
- Laryngospasm is a spasm of intrinsic muscles of the larynx causing closure of the airway at the level of vocal chords. It can be either complete or incomplete.
- The classic sign is a high pitched stridor or crowing for partial obstruction and silence for complete obstruction. Patients may also exhibit paradoxical chest wall and abdominal movements and oxygen desaturation.
- The cause of laryngospasm include local irritation and depth of anesthesia( Inadequate depth can sensitize the airway)
- Prevention includes proper airway maintenance. The surgeon uses throat pack or partition to keep foreign material out of the airway.
- In a suspected case, head should be properly positioned and airway suctioned to clear any foreign bodies.
- 100% oxygen should be administered via full face mask.
With a continuing laryngospasm, the next step is to ventilate the patient. If patients cannot be ventilated, succinylcholine 0.15 to 0.30 mg/kg i.v should be given for partial obstruction and 0.3 to 0.6 mg/kg for complete obstruction.
If the spasm continuous, an intubating dose of succinylcholine 1mg/kg should be given along with endotracheal intubation.
Note: Succinylcholine may act as a triggering agent for MH in patients with family history of MH(Malignant hyperthermia)
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