Nitrous oxide is the most commonly used inhalation anesthetic in dentistry and is commonly used in emergency centers and ambulatory surgery centers as well. When used alone, it is incapable of producing general anesthesia reliably, but it may be combined with other inhalation and/or intravenous agents in deep sedative/general anesthestic techniques. However, as a single agent, it has impressive safety and is excellent for providing minimal and moderate sedation for apprehensive dental patients. To gain a full appreciation of the pharmacology, physiologic influences, and proper use of nitrous oxide, one must compare it with other inhalation anesthetics. The purpose of this CE article is to provide an overview of inhalation anesthetics in general and to address nitrous oxide more specifically in comparison.
General anesthesia; Inhalation anesthetics; Nitrous oxide; Conscious sedation; Moderate sedation
The high risks associated with general anesthesia in obstructive sleep apnea syndrome (OSAS) patients have been reported. Many authors have suggested that the intraoperative administration of opioids and sedatives should be limited or avoided because these drugs selectively impair muscle activity in the upper airway. We report the case of an OSAS patient who was managed with nasal continuous positive airway pressure (NCPAP) and treated safely in spite of the use of conventional anesthetic and analgesic agents typically used for patients without OSAS. She had little pain during the perioperative period. It is suggested that NCPAP is an effective treatment for not only preventing airway obstructive apnea but for allowing the administration of anesthetic and analgesic drugs without major complications.
Obstructive sleep apnea syndrome; NCPAP; Perioperative management
An abstract of this study was presented at the American Association for Dental Research (AADR) Dental Anesthesiology Research Group in Honolulu, Hawaii, in March of 2004. This study was conducted to correlate the intraoperative and postoperative morbidity associated with moderate and deep sedation, also known as monitored anesthesia care (MAC), provided in a General Practice Residency (GPR) clinic under the supervision of a dentist anesthesiologist. After internal review board approval was obtained, 100 parenteral moderate and deep sedation cases performed by the same dentist anesthesiologist in collaboration with second year GPR residents were randomly selected and reviewed by 2 independent evaluators. Eleven morbidity criteria were assessed and were correlated with patient age, gender, American Society of Anesthesiology Physical Status Classification (ASAPS), duration of procedure, and anesthetic protocol. A total of 39 males and 61 females were evaluated. Patients' ASAPS were classified as I, II, and III, with the average ASAPS of 1.61 and the standard deviation (STDEV) of 0.584. No ASPS IV or V was noted. Average patient age was 33.8 years (STDEV, 14.57), and the average duration of procedure was 97.5 minutes (STDEV, 42.39). Three incidents of postoperative nausea and vomiting were reported. All 3 incidents involved the ketamine-midazolam-propofol anesthetic combination. All patients were treated and were well controlled with ondansetron. One incident of tongue biting in an autistic child was regarded as an effect of local anesthesia. One patient demonstrated intermittent premature atrial contractions (PACs) intraoperatively but was stable. Moderate and deep sedation, also known as MAC, is safe and beneficial in an outpatient GPR setting with proper personnel and monitoring. This study did not demonstrate a correlation between length of procedure and morbidity. Ketamine was associated with all reported nausea and vomiting incidents because propofol and midazolam are rarely associated with such events.
Dental sedation; Sedation training; Sedation outcomes
To test the Italian translation of Corah's Dental Anxiety Scale (DAS) and to check the relationship between dental anxiety and the American Society of Anesthesiologists (ASA) physical status classification (ASA-PS), the DAS was translated into Italian and administered to 1072 Italian patients (620 male and 452 female patients, ages 14–85 years) undergoing oral surgery. Patients' conditions were checked and rated according to the ASA-PS. The DAS ranged from 4 to 20 (modus = 8, median = 10); 59.5% of patients had a DAS of 7–12, 26.1% had a DAS >12, and 10.3% had a DAS >15. The mean DAS was 10.29 (95% confidence limit = 0.19); female patients were more anxious than male patients (P < .001), while patients older than 60 years showed a significant decrease in the level of anxiety. Five hundred two patients were rated as ASA-PS class P1, 502 as ASA-PS class P2, and 68 as ASA-PS class P3, with a mean DAS score of 9.69, 10.78, and 11.09, respectively: the DAS difference between groups was significant (P < .001).
Anxiety; Dentistry; Dental anxiety scale; Visual analogue scale; Psychological tests; Methods; Dental phobia; Physical status
Benzodiazepines in intravenous sedation are useful, owing to their outstanding amnesic effect when used for oral surgery as well as dental treatments on patients with intellectual disability or dental phobia. However, compared with propofol, the effect of benzodiazepine lasts longer and may impede discharge, especially when it is administered orally because of fear of injections. Although flumazenil antagonizes the effects of benzodiazepine quickly, its effect on the equilibrium function (EF) has never been tested. Since EF is more objective than other tests, the purpose of this study is to assess the sedation level and EF using a computerized static posturographic platform. The collection of control values was followed by the injection of 0.075 mg/kg of midazolam. Thirty minutes later, 0.5 mg or 1.0 mg of flumazenil was administered, and the sedation level and EF were measured until 150 minutes after flumazenil administration. Flumazenil antagonized sedation, and there was no apparent resedation; however, it failed to antagonize the disturbance in EF. This finding may be due to differences in the difficulty of assessing the sedation level and performing the EF test, and a greater amount of flumazenil may effectively antagonize the disturbance in EF.
Midazolam; Equilibrium function; Flumazenil; Reversal; Sedation
Appropriate preoperative assessment of dental patients should always include analysis of their medications. Psychiatric illnesses including panic/anxiety disorder, depression, psychoses, and manic disorders are prevalent within our society. An impressive number of drug formulations are prescribed for these disorders, and they introduce concern regarding side effects and possible drug interactions with medications the dentist may deem necessary for dental care. This article will address essential pharmacology of these psychotropic medications.
Preoperative assessment; Drug interactions; Drug side effects; Drug toxicity; Psychotropic drugs
This study investigated the physiologic and sedative parameters associated with a low-dose infusion of dexmedetomidine (Dex). Thirteen healthy volunteers were sedated with Dex at a loading dose of 6 mcg/kg/h for 5 minutes and a continuous infusion dose of 0.2 mcg/kg/h for 25 minutes. The recovery process was observed for 60 minutes post infusion. The tidal volume decreased significantly despite nonsignificant changes in respiratory rate, minute ventilation, oxygen saturation, and end-tidal carbon dioxide. The mean arterial pressure and heart rate also decreased significantly but within clinically acceptable levels. Amnesia to pin prick was present in 69% of subjects. A Trieger dot test plot error ratio did not show a significant change at 30 minutes post infusion despite a continued significant decrease in bispectral index. We conclude that sedation with a low dose of Dex appears to be safe and potentially efficacious for young healthy patients undergoing dental procedures.
Dexmedetomidine; Sedation; α2-Agonist; Amnesia; Dental procedure
The Airtraq laryngoscope is a new intubation device that provides a non–line-of-sight view of the glottis. We evaluated this device by comparing the ease of nasotracheal intubation on a manikin with the use of Airtraq versus the Macintosh laryngoscope with and without Magill forceps. Nasotracheal intubation on a manikin was performed by 20 anesthesiologists and 20 residents with the Airtraq or Macintosh laryngoscope. The mean (± SD) time required for nasotracheal intubation by the residents was significantly shorter with the Airtraq laryngoscope than with the Macintosh laryngoscope (16 ± 7 sec vs 22 ± 10 sec; P < .001), but no difference in intubation time was observed between Airtraq (15 ± 11 sec) and Macintosh (13 ± 6 sec) laryngoscopy by the anesthesiologists. The Magill forceps was used more frequently to facilitate intubation with the Macintosh laryngoscope than with the Airtraq laryngoscope in both groups of operators 7(P < .001). The Airtraq laryngoscope scored better on the visual analog scale than did the Macintosh laryngoscope in both groups of operators (P < .05). The Airtraq laryngoscope offers potential advantages over standard direct laryngoscopy for nasotracheal intubation.
Intubation; Nasotracheal; Videolaryngoscope
Appropriate preoperative assessment of the dental patient should always include an analysis of the patient's medications. Cardiovascular diseases are the most common group of medical disorders that dentists encounter, and the number of drugs prescribed for managing these conditions is staggering. This justifiably raises concern and probable confusion regarding side effects and possible drug interactions with medications the dentist may deem necessary for dental care. This continuing education article is the second in a series that will address essential pharmacology of medications commonly prescribed for chronic medical care. A reasonable understanding of these agents will allow the dentist to better appreciate the medical status of their patients, to appreciate the actual risks associated with antithrombotic medications, and to avoid adverse interactions with drugs the dentist might administer or prescribe.
Preoperative assessment; Drug interactions; Drug side effects; Drug toxicity; Anticoagulants; Postoperative bleeding
Phentolamine mesylate accelerates recovery from oral soft tissue anesthesia in patients who have received local anesthetic injections containing a vasoconstrictor. The proposed mechanism is that phentolamine, an alpha-adrenergic antagonist, blocks the vasoconstriction associated with the epinephrine used in dental anesthetic formulations, thus enhancing the systemic absorption of the local anesthetic from the injection site. Assessments of the pharmacokinetics of lidocaine and phentolamine, and the impact of phentolamine on the pharmacokinetics of lidocaine with epinephrine were performed to characterize this potentially valuable strategy. The blood levels of phentolamine were determined following its administration intraorally and intravenously. Additionally, the effects of phentolamine mesylate on the pharmacokinetics of intraoral injections of lidocaine with epinephrine were evaluated. Sixteen subjects were enrolled in this phase 1 trial, each receiving 4 drug treatments: 1 cartridge lidocaine/epinephrine followed after 30 minutes by 1 cartridge phentolamine (1L1P), 1 cartridge phentolamine administered intravenously (1Piv), 4 cartridges lidocaine/epinephrine followed after 30 minutes by 2 cartridges phentolamine (4L2P), and 4 cartridges lidocaine/epinephrine followed by no phentolamine (4L). Pharmacokinetic parameters estimated for phentolamine, lidocaine, and epinephrine included peak plasma concentration (Cmax), time to peak plasma concentration (Tmax), area under the plasma concentration-time curve from 0 to the last time point (AUClast) or from time 0 to infinity (AUCinf), elimination half-life (t1/2), clearance (CL), and volume of distribution (Vd). The phentolamine Tmax occurred earlier following the intravenous administration of 1Piv (7 minutes than following its submucosal administration in treatment 1L1P (15 minutes) or 4L2P (11 minutes). The phentolamine t1/2, CL, and Vd values were similar for 1L1P, 1Piv, and 4L2P. The Tmax for lidocaine occurred later and the Cmax for lidocaine was slightly higher when comparing the 4L2P treatment and the 4L treatment. The phentolamine-induced delay of the lidocaine Tmax likely represents phentolamine's ability to accelerate the systemic absorption of lidocaine from oral tissues into the systemic circulation.
Pharmacokinetics; Dental local anesthesia; Lidocaine; Phentolamine; Epinephrine
The objectives of this study were to compare history and physical examinations (H&Ps) done by community-based physicians and dentist anesthesiologists for children undergoing general anesthesia for dental rehabilitation. One hundred sixty-eight records were evaluated from the Nationwide Children's Hospital Dental Surgery Center of patients anesthetized between June 2006 and March 2007. These patients had H&Ps completed by both a community-based physician and a dentist anesthesiologist prior to general anesthesia. H&P forms were reviewed by the 3 authors to identify missing data, American Society of Anesthesiologists (ASA) classification, and impact on care. There was a statistically significant difference with respect to 10 of 17 sections examined, with the community-based physicians' H&Ps tending to be incomplete more often. Over 20% of community-based physicians made no mention of the history of present illness. One third of all physician H&Ps were missing vital sign recordings. No significant difference was noted between the physicians' and dentist anesthesiologists' ratings of ASA status. The physician H&P altered course of anesthesia treatment in <1% of studied cases. Statistically significant deficiencies were noted in the physician H&P in 60% of categories.
Dentist anesthesiologist; General anesthesia; Outpatient surgery; History and physical
The objective of this randomized double-blind investigation was to compare the anesthetic efficacy and injection discomfort of 3 volumes of 2% lidocaine with 1∶100,000 epinephrine for maxillary infiltration anesthesia. A total of 25 subjects received 0.6, 0.9, and 1.2 mL of the anesthetic buccal to an upper canine. Test teeth were assessed with electrical stimulation to determine onset and duration of pulpal anesthesia; soft tissue anesthesia and injection discomfort were assessed by pin-prick test and visual analog scale (VAS). Data were analyzed by 2-way analysis of variance (ANOVA), Friedman, and chi-square tests (α = 5%). The 1.2 mL dose induced faster onset of pulpal anesthesia, a higher success rate, and a longer duration of soft tissue/pulpal anesthesia than were achieved with the other doses (P < .05). No differences in injection discomfort were observed between treatments. It is concluded that maxillary infiltration anesthesia with lidocaine and epinephrine has a faster onset, a greater success rate, and a longer duration when a volume of 1.2 mL is used than when volumes less than 1.0 mL are used.
Lidocaine; Anesthetic efficacy; Infiltration anesthesia
The authors, using a crossover design, randomly administered, in a single-blind manner, 3 primary intraosseous injections to 61 subjects using: the Wand local anesthetic system at a deposition rate of 45 seconds (fast injection); the Wand local anesthetic system at a deposition rate of 4 minutes and 45 seconds (slow injection); a conventional syringe injection at a deposition rate of 4 minutes and 45 seconds (slow injection), in 3 separate appointments spaced at least 3 weeks apart. A pulse oximeter measured heart rate (pulse). The results demonstrated the mean maximum heart rate was statistically higher with the fast intraosseous injection (average 21 to 28 beats/min increase) than either of the 2 slow intraosseous injections (average 10 to 12 beats/min increase). There was no statistically significant difference between the 2 slow injections. We concluded that an intraosseous injection of 1.4 mL of 2% lidocaine with 1 : 100,000 epinephrine with the Wand at a 45-second rate of anesthetic deposition resulted in a significantly higher heart rate when compared with a 4-minute and 45-second anesthetic solution deposition using either the Wand or traditional syringe.
Intraosseous; Heart rate; Slow and fast injections
The aim of this study was to compare the effectiveness of 2 different volumes of anesthetic solution for a premolar-molar extraction, and to determine the onset of complete mandibular conduction anesthesia via a Gow-Gates mandibular block. One operator performed 32 blocks with a 27-gauge needle on patients who required a dental extraction: 16 blocks using 1.8 mL of anesthetic solution, and 16 blocks using 3.6 mL of anesthetic solution. The parameters evaluated were frequency of successful anesthesia and onset of complete anesthesia. Significant differences (P < .005) were observed in the evaluation of volume: the 3.6 mL group yielded a higher success rate (82.5%) than the 1.8 mL group (17.5%). The onset of complete conduction anesthesia was achieved in 8 minutes by 56% of the subjects (9 of 16) with 3.6 mL and only one subject in 16 (6%) with 1.8 mL. A larger volume of anesthetic solution (3.6 mL) is required to achieve a higher success rate and a faster onset of action for a dental extraction without the use of reinforcement anesthesia. The volume of anesthetic solution is indirectly proportional to the onset of complete anesthesia. A premolar-molar extraction can be done, with 3.6 mL of anesthetic solution, in more than 50% of the patients 8 minutes after injection.
Gow-Gates; Mandibular conduction anesthesia; Mandibular block; Onset of complete anesthesia; Needle deflection