Anesthetic management by laryngeal mask airway in a patient with a history of difficult intubation resulting in dental injuries.

Disabled patients may face respiratory problems during general anesthesia because of head and neck anomalies. We describe a case of dental treatment under general anesthesia using a laryngeal mask airway in a disabled patient who faced difficulty in endotracheal intubation on several occasions, 5 of which resulted in dental injuries.

Repeated General Anesthesia in a Patient With Noonan Syndrome.

Noonan syndrome (NS) is an autosomal dominant disorder characterized by facial anomalies, short stature, chest deformity, congenital heart diseases, and other comorbidities. The challenges faced during anesthetic management of patients with NS could be due to congenital heart diseases, hemostatic disorders, and airway anomalies. Here we describe dental treatment under general anesthesia performed for a 28-year-old man with NS. He had characteristic features of NS along with mild pulmonary valve stenosis. Dental treatment under general anesthesia was performed successfully on 13 occasions with nasotracheal intubation under curve-tipped suction catheter guidance or insertion of a reinforced laryngeal mask airway. This case suggests that for patients with NS, who might present several challenges, dental anesthesiologists should consider the extent of the patient's disorders to enable them to perform dental treatment safely under general anesthesia.

Comparison of insertion of the modified i-gel airway for oral surgery with the LMA Flexible: a manikin study.

We previously modified the i-gel airway to enable its use in the field of oral and maxillofacial surgery and reported its fabrication methods. In general, the standard i-gel airway is quick to insert and has a high success rate, but the modified i-gel airway has yet to be assessed for these attributes. We, therefore, set out to compare the ease of insertion of the modified i-gel airway with the LMA Flexible to investigate the usefulness of the modified i-gel airway. The study participants, who included 20 new interns with no experience using either the LMA Flexible or the modified i-gel airway, inserted each device 3 times into an intubation practice manikin. The variables measured in this study were insertion time and rate of successful insertions. Mean insertion time over 3 attempts was significantly shorter for the modified i-gel™ airway (18.9 ± 4.7 seconds) than the LMA Flexible (24.9 ± 5.1 seconds, P < .001). The rate of successful insertions as a total of all 3 attempts was significantly higher for the modified i-gel airway (56/60 times, 93.3%) than the LMA Flexible (45/60 times, 75%; P = .012). When used by an inexperienced operator, the modified i-gel™ airway is faster and has a higher success rate than the LMA Flexible, suggesting that it can be easily manipulated during insertion.

Ventilation via cut nasotracheal tube during general anesthesia.

Many patients with disabilities need recurrent dental treatment under general anesthesia because of high caries prevalence and the nature of dental treatment. We evaluated the use of a nasal device as a possible substitute for flexible laryngeal mask airway to reduce the risk of unexpected failure accompanying intubation; we succeeded in ventilating the lungs with a cut nasotracheal tube (CNT) with its tip placed in the pharynx. We hypothesized that this technique would be useful during dental treatment under general anesthesia and investigated its usefulness as part of a minimally invasive technique. A prospective study was designed using general anesthesia in 37 dental patients with disabilities such as intellectual impairment, autism, and cerebral palsy. CNT ventilation was compared with mask ventilation with the patient in 3 positions: the neck in flexion, horizontal position, and in extension. The effect of mouth gags was also recorded during CNT ventilation. The percentages of cases with effective ventilation were similar for the 2 techniques in the neck extension and horizontal positions (89.2-97.3%). However, CNT ventilation was significantly more effective than mask ventilation in the neck flexion position (94.6 vs 45.9%; P < .0001). Mouth gags slightly reduced the rate of effective ventilation in the neck flexion position. Most dental treatments involving minor oral surgeries were performed using mouth gags during CNT ventilation. CNT ventilation was shown to be superior to mask ventilation and is useful during dental treatment under general anesthesia.

Comparison of the Ambu AuraFlex with the laryngeal mask airway Flexible: a manikin study.

PURPOSE: The present study compared the Ambu AuraFlex and the laryngeal mask airway (LMA) Flexible with regard to time required for and success rates of insertion on a manikin by dental students who had never used an LMA. In addition, participants' views on ease of insertion of each device were surveyed. MATERIALS AND METHODS: Subjects consisted of 30 dental students who inserted each airway device in a manikin. The time required for and success rates of insertion were measured. Subjects were then asked to rate the ease of insertion of each device using the 100-mm visual analog scale (from 0 mm = extremely easy to 100 mm = extremely difficult). RESULTS: Insertion time was shorter with the Ambu AuraFlex (26.6 ± 7.1 seconds) than with the LMA Flexible (30.3 ± 6.8 seconds; P = .045). The rate of successful insertion using the Ambu AuraFlex (28 of 30 attempts, 93.3%) was greater than that with the LMA Flexible (23 of 30 attempts, 76.7%), although the difference was not statistically significant (P = .145). Ambu AuraFlex insertion was considered less difficult (median, 41 mm; 10th to 90th percentiles, 18 to 78 mm) than LMA Flexible insertion (60 mm; 42 to 82 mm; P = .004), as rated using the 100-mm visual analog scale. CONCLUSIONS: The Ambu AuraFlex appears to be useful for inexperienced users because it enables quicker and easier insertion than the LMA Flexible.

Effects of head-neck extension on abnormality of laryngeal mask airway function resulting from opening the mouth.

PURPOSE: This study investigated the effects of head-neck extension on abnormalities of laryngeal mask airway (LMA) function resulting from opening the mouth. PATIENTS AND METHODS: A single, experienced LMA user inserted the LMA in 15 patients scheduled for elective oral surgery. Oropharyngeal leak pressure and intracuff pressure were sequentially documented in 5 mouth conditions in order (0 minutes, mouth closed plus 0° extension; 3 minutes, mouth open plus 0° extension; 6 minutes, mouth open plus 15° extension; 9 minutes, mouth open plus 30° extension; and 12 minutes, mouth open plus 45° extension). RESULTS: Oropharyngeal leak pressures with the mouth open plus 0° extension (30.7 ± 5.6 cm H(2)O, P < .001), mouth open plus 15° extension (29.1 ± 6.8 cm H(2)O, P < .001), and mouth open plus 30° extension (25.7 ± 6.1 cm H(2)O, P < .001) were significantly higher than with the mouth closed plus 0° extension (19.7 ± 2.8 cm H(2)O). Compared with the position with the mouth closed plus 0° extension (60.0 ± 0 cm H(2)O), intracuff pressures were also higher with the mouth open plus 0° extension (84.5 ± 14.1 cm H(2)O, P < .001), mouth open plus 15° extension (77.4 ± 11.0 cm H(2)O, P < .001), and mouth open plus 30° extension (73.6 ± 9.6 cm H(2)O, P < .001). Both measurement values returned to control levels when the position with the mouth open plus 45° extension was assumed (oropharyngeal leak pressure, 64.5 ± 6.5 cm H(2)O [P = .212]; intracuff pressure, 20.2 ± 4.9 cm H(2)O [P = .969]). CONCLUSIONS: In procedures requiring the patient to have an open mouth under general anesthesia using LMA, 45° head-neck extension achieves acceptable airway conditions.

Optimal degree of mouth opening for laryngeal mask airway function during oral surgery.

PURPOSE: This study was performed to determine the optimal degree of mouth opening in anesthetized patients requiring laryngeal mask airway (LMA) during oral surgery. PATIENTS AND METHODS: A single, experienced LMA user inserted the LMA in 15 patients who were scheduled for elective oral surgery. Oropharyngeal leak pressure, intracuff pressure, and fiberoptic assessment of the LMA position were sequentially documented in 5 mouth conditions-opening of 1.4 (neutral position), 2, 3, 4, and 5 cm-and any resulting ventilatory difficulties were recorded. RESULTS: Oropharyngeal leak pressure with the mouth open 4 cm (21.8 ± 3.2 cm H(2)O, P = .025) and 5 cm (27.3 ± 7.2 cm H(2)O, P < .001) was significantly higher than in the neutral position (18.1 ± 1.5 cm H(2)O), as was intracuff pressure (neutral position, 60.0 ± 0 cm H(2)O; 4 cm, 72.6 ± 5.1 cm H(2)O [P < .001]; and 5 cm, 86.9 ± 14.4 cm H(2)O [P < .001]). LMA position, observed by fiberoptic bronchoscopy, was unchanged by mouth opening, being similar in the 5 mouth conditions (P = .999). In addition, ventilation difficulties (abnormal capnograph curves or inadequate tidal volume) occurred in 2 of 15 patients (13%) and 7 of 15 patients (53%) (P < .001) with the mouth opening of 4 and 5 cm, respectively. CONCLUSIONS: This study showed that a mouth opening over 4 cm led to substantial increases in oropharyngeal leak pressure and intracuff pressure of the LMA, warranting caution, because gastric insufflation, sore throat, and ventilation difficulties may occur. A mouth opening of 3 cm achieves acceptable airway conditions for anesthetized patients requiring LMA.

The influence of head and neck position on ventilation with the i-gel airway in paralysed, anaesthetised patients.

CONTEXT AND OBJECTIVE: We hypothesised that head and neck position could affect the effectiveness of ventilation with the i-gel airway. To test this hypothesis, we investigated the influence of different head and neck positions on oropharyngeal sealing pressures and ventilation scores during ventilation with i-gel. METHODS: A single, experienced supraglottic airway device user inserted the i-gel in 20 paralysed, anaesthetised patients who were scheduled for oral surgery. Oropharyngeal leak pressures and ventilation scores were measured with the head and neck in the neutral position, flexed, extended or rotated to the right. Ventilation was scored from 0 to 3 based on three criteria (no leakage with an airway pressure of 15 cmH2O, bilateral chest excursion and a square wave capnogram; each item scoring 0 or 1 point). RESULTS: Compared with the neutral position (25.8 ± 5.2 cmH2O), oropharyngeal leak pressure was significantly higher with flexion (28.5 ± 3.4 cmH2O, P=0.015) and lower with extension (23.0 ± 4.2 cmH2O, P=0.015), but similar with rotation (26.7 ± 5.1 cmH2O, P=0.667). Flexion of the head and neck [2 (1-3)] adversely affected the ventilation score compared with the neutral position [3 (2-3), P=0.004]. CONCLUSION: Effective ventilation with an i-gel can be performed in patients in whom the head and neck is extended or rotated, whereas flexion of the head and neck adversely affects ventilation. Clinically, flexion of the head and neck should be avoided during ventilation with the i-gel.

The influence of mouth opening on oropharyngeal leak pressure, intracuff pressure, and cuff position with the laryngeal mask airway.

PURPOSE: The aim of this study was to investigate the influence of mouth opening on oropharyngeal leak pressure, intracuff pressure, and cuff position of the laryngeal mask airway (LMA). PATIENTS AND METHODS: Fifteen patients who were scheduled for elective oral surgery were recruited into this study. A single, experienced LMA user inserted the LMA according to the manufacturer's recommended technique. Oropharyngeal leak pressure, intracuff pressure, and fiberoptic assessment of the LMA position were documented under 3 mouth conditions: neutral position (1.4-cm distance between upper and lower incisors), mouth open (5- to 6-cm distance between upper and lower incisors), and return to the neutral position. Any ventilation difficulties under the 3 mouth conditions were recorded. RESULTS: Oropharyngeal leak pressure with the mouth open was higher than in the neutral position (P < .001). Compared with the neutral position, intracuff pressure was also higher with the mouth open (P < .001). Both measurement values returned to control levels when the neutral position was once again assumed. The LMA position observed by fiberoptic bronchoscopy was unchanged by mouth opening and was similar in the 3 mouth conditions (P = .998). Although ventilatory difficulties occurred after mouth opening in 8 of 15 patients (P < .001), it did not occur when the neutral position was reassumed. CONCLUSIONS: This study showed that mouth opening led to substantial increases in oropharyngeal leak pressure and intracuff pressure of the LMA, warranting caution because gastric insufflation, sore throat, and ventilation difficulties may occur.

Changes in blood pressure during induction of anesthesia and oral and maxillofacial surgery by type and timing of discontinuation of antihypertensive drugs.

The purpose of this study was to evaluate the effects of an antihypertensive drug class and the timing of discontinuation of antihypertensive therapy on blood pressure during oral and maxillofacial surgery for 129 patients on antihypertensive therapy receiving general anesthesia. Blood pressures at loss of response to stimulation and 5-15 minutes after intubation were significantly lower than those before induction, although the type of antihypertensive therapy did not affect changes in blood pressure. No significant correlation was observed between systolic blood pressure (SBP) on the ward and change in SBP during surgery, though patients with higher blood pressure on the ward tended to exhibit larger differences between SBP on the ward and the lowest SBP during surgery. Frequency of use of vasopressors during surgery was significantly higher in patients who discontinued antihypertensive therapy on the day before surgery than in those who continued antihypertensive therapy on the day of surgery. These findings suggest that appropriate preoperative antihypertensive therapy is important for minimizing change in blood pressure during surgery and preventing perioperative complications. Patients undergoing antihypertensive therapy should be carefully monitored perioperatively by observation for interactions between antihypertensive and anesthetic agents and minimizing interruption schedules for antihypertensive therapy.

[Difficult airway management for general anesthesia in two patients with Kartagener syndrome].

Two patients with Kartagener syndrome were managed under general anesthesia by nasal intubation for sagital split ramus osteotomy. Many episodes of expectoration were encountered in the former patient's perioperative period and the expectoration discharge was inadequate by postoperative nausea, leading to trouble in airway management. In the second patient, tube collapse was caused after intubation by serious nasal cavity strangulation, and re-intubation was necessary. Expectoration is seen resulting from decreased ciliary function with bronchiectasis during anesthetic management of patients with Kartagener syndrome. It is important to prevent lung complications by nausea prevention and pain killing in the postoperative period, in addition to proper suctioning in the perioperative period. Furthermore, there is nasal cavity narrowing by chronic sinusitis. When performing nasal intubation, the difficult airway management is required.

Utility of the Portex introducer, ivory type, as a tube exchanger.

PURPOSE: This study compared the Portex introducer, ivory type (PII) (Portex Tracheal Tube Introducer; SIMS Portex, Hythe, Kent, England), and Cook Airway Exchange Catheter (CAEC) (Cook, Letchworth, Hertfordshire, England) with regard to success rate of and time required for tracheal intubation by use of each device by oral and maxillofacial surgeons on a manikin. MATERIALS AND METHODS: The subjects comprised 17 oral and maxillofacial surgeons who intubated the trachea of the manikin with each device. The PII or CAEC was inserted into the trachea of the manikin and advanced 26 cm from the upper incisor, and the time required for intubation was measured. The subjects were then asked to rate the difficulty of intubation using a 10-cm visual analog scale. RESULTS: The mean intubation time, averaged over 3 attempts, was significantly shorter for the PII (7.92 +/- 3.15 seconds) than for the CAEC (11.44 +/- 3.98 seconds) (P < .001). The rate of successful intubation with the PII (88.2%) was significantly greater than that with the CAEC (37.3%) (P < .001). With regard to the overall difficulty of intubation, as rated by the 10-cm visual analog scale, the PII (median, 45 mm [10th-90th percentile, 32-53 mm]) was considered less difficult than the CAEC (median, 66 mm [10th-90th percentile, 52-84 mm]) (P < .001). CONCLUSIONS: Intubation is faster, more sure, and easier by use of the PII as a tube exchanger than with the CAEC. This may be particularly important for patients undergoing oral and maxillofacial surgery as a result of anatomic changes in the airway, because edema or hematoma in the upper airway often leads to failed intubation. We conclude that the PII is useful as a tube exchanger.

Second-degree atrioventricular block type II and third-degree atrioventricular block requiring cardiac pacing after tooth extraction.

Because atrioventricular block can cause cardiovascular collapse, the rapid management of this condition is necessary. An 82-year-old man complained of discomfort after tooth extraction, and electrocardiography showed second- and third-degree atrioventricular blocks. Dentists should monitor patients who report discomfort using electrocardiography because of the possibility of life-threatening arrhythmia.

Influences of molar loss of rat on learning and memory.

PURPOSE: The maxillary unilateral or bilateral molars of rats were extracted, and the influences of the partial loss of occlusal support were evaluated using an 8-arm radial maze and a step-through type passive-avoidance apparatus. METHODS: Rats were randomly allocated to three groups not undergoing molar extraction or undergoing extraction of the maxillary unilateral or bilateral molars. Each group was further divided into two groups for maze or passive-avoidance experiments. Thus, a total of six groups were established. The maze experiment was conducted once daily for 10 days. The number of correct choices, number of errors, and the trial time were recorded. The passive-avoidance experiment consisted of an acquisition trial and retention trial. In the acquisition trial, rats were placed in a light room, and the response latency until their entry into a dark room was measured. After 24h, a similar procedure was performed as a retention trial. RESULTS: In the maze experiment, there was no significant difference by all the groups except on the day 1 in the number of correct choices. But bilateral molar loss group, the number of errors were significantly lower than no extraction group on days 1, 2, 3, 4, and 7. In the passive-avoidance experiment, though the response latency in the retention trial was longer than that in the acquisition trial in all three groups, according to the increase in the number of tooth extraction, it became significantly shorter between P1 and P3. CONCLUSION: These results suggested that molar loss may be a cause of learning/memory impairment.