The respiratory effects of drugs used for conscious sedation and general anesthesia

Article Abstract:

Most dental treatment can be carried out with local anesthesia, in conjunction with sedation and reduction of anxiety (achieved by use of anxiolytic drugs), rather than general anesthesia. The main danger of conscious sedation is respiratory depression. Several drugs commonly used in dental anesthesia have been evaluated. Breathing is controlled by two centers in the brain; the first is sensitive to chemicals in the blood (the central chemosensitive center); when stimulated, it arouses a second center that signals the breathing muscles to function. A chemical change that stimulates the first reaction is an increase in hydrogen ion concentration, which is usually associated with excess carbon dioxide in the blood. Other sensors that affect breathing are located in the carotid and aorta arteries; they are activated only when oxygen is in very short supply, therefore serve a 'backup' function. When the central chemosensitive center is depressed by a drug, the control exerted by carotid and aortic artery receptors becomes more salient. A final important respiratory mechanism in the conscious patient is the patient's own voluntary control of respiration. Depression of the central or arterial respiratory control regions is of paramount concern in dental sedation. Opioid-agonist (opioid-like) drugs depress the respiratory center. Benzodiazepine drugs do not seem to affect the central chemosensitive region, but have an effect on inhalation. Nitrous oxide reduces the effect of the receptors that signal when oxygen is too low, but does not seem to affect the body's response to excess carbon dioxide. This could be dangerous for people with chronic obstructive lung disease, whose respiration is dependent on signals from peripheral sensors. In dental practice, verbal contact with the patient is the best way to assure adequate ventilation, since he can always be told to breathe more deeply if a problem is observed. Equipment is available to monitor carbon dioxide concentration in expired air, or to determine oxygen saturation in the blood by measuring the pulse (pulse oximetry). Any sedating drug can depress ventilation, and the dentist can use pulse oximetry as a warning system. Careful monitoring throughout the procedure, as well as accurate determination of the patient's medical history, must remain the paramount concern when sedating agents are used. (Consumer Summary produced by Reliance Medical Information, Inc.)

Laws, regulations and rules, Respiration, Sedatives, Hypnotics and sedatives

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Unusual allergic reaction follows allergy testing

Article Abstract:

The case history of a 41-year-old woman who needed extensive dental work is presented; it is of interest because the patient already had a history of allergies to several drugs, including penicillin, sulfa, erythromycin, and local anesthetic agents. In addition, the patient had been hospitalized because of allergic reactions. Because of this, she was referred to an allergy clinic for testing prior to undergoing dental work (which required local anesthesia). For the allergy testing, several agents were to be applied as small local injections and the allergic response was to be noted. Testing took place between 1 and 1:30 PM, after which the patient was discharged. Skin reactions to some substances had been noted. The patient returned 15 minutes after discharge from the clinic, when she experienced chest tightness and difficulty breathing. She collapsed and received emergency treatment, then was admitted to the emergency room and, eventually, to intensive care. After two days' treatment, the patient was discharged. The diagnosis was immunoglobulin E-mediated allergy to five of the seven anesthetics that had been tested; the recommendation was made that general anesthesia be given for all dental procedures. This was subsequently done, without complications. The case illustrates the importance of taking drug allergy histories prior to the use of local anesthetics. Its outcome is ironic, since the purpose of the allergy clinic referral was to avoid such an allergic reaction (anaphylactic reaction) at the dentist's. (Consumer Summary produced by Reliance Medical Information, Inc.)

Case studies, Allergy

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Relieving patient anxiety: a new approach

Article Abstract:

Success in reducing patient anxiety before oral surgery is reported by scientists at the National Institute of Dental Research, who evaluated the effects of a drug normally prescribed as a sleeping aid. Seventy-five patients received one of five treatments before undergoing extraction of a third molar: (1) the drug, oral triazolam (similar to diazepam, or Valium, and sold as Halcion); (2) nitrous oxide; (3) triazolam plus nitrous oxide; (4) intravenous diazepam; or (5) oral placebo (inactive drug) plus oxygen. All patients received a local anesthetic prior to extraction. Anxiety and amnesia were evaluated after surgery, and physiological signs and effects on movement were monitored before and after drug administration, and one day later. Although all patients said their anxiety increased during the extractions, those who received triazolam and intravenous diazepam reported the lowest levels of anxiety. Triazolam plus nitrous oxide was no more effective than triazolam alone. Since the drug does not cause drowsiness, patients who took triazolam recovered faster than those who received diazepam. Furthermore, the use of oral medication to reduce anxiety may be attractive to people who ordinarily would avoid dental care because of fear of pain. (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Triazolam

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