Masafumi Akatsuka

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.

Damaged Univent tubes.

The patient was a 62-yr-old, 158-cm, 58-kg man scheduled for surgery with a diagnosis of esophageal cancer. After placement of a 8.5-mm single-lumen cuffed Univent@ tube made of silicon, the built-in cuff was advanced into the right mainstem bronchus with the aid of fiberoptic bronchoscopy. The bronchial blocker cuff was inflated to permit one-lung ventilation that was confirmed by auscultation of the lungs. The patient was in a left semilateral decubitus position, and the operating table was rotated to the left according to the surgical procedure. During two-lung ventilation, analysis of arterial blood gases was normal, and pulse oximetry showed 99%-100% oxygen saturation. However, during one-lung ventilation, oxygen saturation decreased to 93%, and Pao, gradually decreased from 130 to 52 mmHg despite the inhalation of 100% oxygen. One-lung ventilation time was 90 min in total, and during this period, both lungs were ventilated manually a few times until oxygen saturation recovered to 100%. Surgery was completed in 6 h 20 min; the anesthesia time was 7 h 40 min. The patient entered the intensive care unit with the Univent@ endotracheal tube still in place. When the trachea was suctioned, using a fiberoptic bronchoscope, we found a foreign body at the proximal region of the left anterior segmental bronchus, and the object was removed. As it seemed to be a silicon fragment, the Univent@ endotracheal tube was replaced with a singlelumen tube, and we inspected the Univent@ tube carefully. The inner part where a slip joint (a tracheal tube connector) attached to the tube was broken, and the object that was removed from the patient’s bronchus fit perfectly into the defective area (Fig. 1). Neither atelectasis nor the foreign object was seen on chest radiograph taken immediately after the patient entered the intensive care unit.

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 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 manufacturers 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.

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.