Direct measurement of mucosal pressures exerted by cuff and non-cuff portions of tracheal tubes with different cuff volumes and head and neck positions

We measured directly mucosal pressures against the cuff and non-cuff portions of the tracheal tube in different head-neck positions and tested the reliability of calculated mucosal pressures, in vivo intracuff pressures and cuff volume as determinants of directly measured mucosal pressures. We studied 10 anaesthetized, paralysed adult patients. An 8.5-mm, high volume, low pressure PVC tracheal tube was used. Microchip sensors were attached to three cuff locations (anterior, lateral and posterior) and two non-cuff locations (anterior tip and anterior aspect of the tube, 5 cm proximal to the cuff). Directly measured mucosal pressures, in vivo intracuff pressures and calculated mucosal pressures (in vivo minus in vitro intracuff pressures) were determined after brief inflation (< 15 s) to 0, 5, 10 and 15 ml. In vivo intracuff pressures were then set at 30 mm Hg and the measurements repeated, first in the neutral position and then with the head-neck extended, flexed and rotated. Cuff mucosal pressures were highest anteriorly and lowest posteriorly. Non-cuff mucosal pressures did not vary with cuff volume and were approximately 15 mm Hg. Compared with the neutral position, in vivo intracuff pressures were higher in the rotated, extended and flexed positions. Compared with the neutral position, mucosal pressure increased on the anterior aspect of the tube in the flexed position by 22 mm Hg (P = 0.003), at the anterior tip in the extended position by 11 mm Hg (P = 0.002) and at the anterior tip (5 mm Hg, P = 0.05) and lateral aspect of the cuff (5 mm Hg, P = 0.03) in the rotated position. In vivo intracuff pressures and calculated mucosal pressures were moderate predictors of measured mucosal pressures; cuff volume was a poor predictor. We conclude that tracheal mucosal pressures were highest anteriorly, that non-cuff portions of the tube exerted substantial mucosal pressures and that the rotated position caused a greater increase in tracheal mucosal pressure than the extended or flexed position. Indirect methods of measuring mucosal pressure were of moderate predictive value

Use of a lighted stylet for intubation via the laryngeal mask airway

To assess a new technique for intubation via the laryngeal mask airway (LMA) in which a lighted stylet is used to optimise the position of the LMA before intubation

Direct measurement of mucosal pressures exerted by cuff and non-cuff portions of tracheal tubes with different cuff volumes and head and neck positions

We measured directly mucosal pressures against the cuff and non-cuff portions of the tracheal tube in different head-neck positions and tested the reliability of calculated mucosal pressures, in vivo intracuff pressures and cuff volume as determinants of directly measured mucosal pressures. We studied 10 anaesthetized, paralysed adult patients. An 8.5-mm, high volume, low pressure PVC tracheal tube was used. Microchip sensors were attached to three cuff locations (anterior, lateral and posterior) and two non-cuff locations (anterior tip and anterior aspect of the tube, 5 cm proximal to the cuff). Directly measured mucosal pressures, in vivo intracuff pressures and calculated mucosal pressures (in vivo minus in vitro intracuff pressures) were determined after brief inflation (< 15 s) to 0, 5, 10 and 15 ml. In vivo intracuff pressures were then set at 30 mm Hg and the measurements repeated, first in the neutral position and then with the head-neck extended, flexed and rotated. Cuff mucosal pressures were highest anteriorly and lowest posteriorly. Non-cuff mucosal pressures did not vary with cuff volume and were approximately 15 mm Hg. Compared with the neutral position, in vivo intracuff pressures were higher in the rotated, extended and flexed positions. Compared with the neutral position, mucosal pressure increased on the anterior aspect of the tube in the flexed position by 22 mm Hg (P = 0.003), at the anterior tip in the extended position by 11 mm Hg (P = 0.002) and at the anterior tip (5 mm Hg, P = 0.05) and lateral aspect of the cuff (5 mm Hg, P = 0.03) in the rotated position. In vivo intracuff pressures and calculated mucosal pressures were moderate predictors of measured mucosal pressures; cuff volume was a poor predictor. We conclude that tracheal mucosal pressures were highest anteriorly, that non-cuff portions of the tube exerted substantial mucosal pressures and that the rotated position caused a greater increase in tracheal mucosal pressure than the extended or flexed position. Indirect methods of measuring mucosal pressure were of moderate predictive value

Puhringer F: Airway management during spaceflight: a comparison of four airway devices in simulated microgravity. ANESTHESIOLOGY

Background: The authors compared airway management in normogravity and simulated microgravity with and without restraints for laryngoscope-guided tracheal intubation, the cuffed oropharyngeal airway, the standard laryngeal mask airway, and the intubating laryngeal mask airway. Methods: Four trained anesthesiologist-divers participated in the study. Simulated microgravity during spaceflight was obtained using a submerged, full-scale model of the International Space Station Life Support Module and neutrally buoyant equipment and personnel. Customized, full-torso manikins wer

Anesthesia for inguinal hernioplasty: a comparison of techniques.

New surgical and modern anaesthesia techniques for inguinal hernioplasty have significantly reduced the duration of the procedure and the postoperative length of hospital stay. From 1994 to 1998, 405 patients with a mean age of 54.7 years (range: from 18 to 90) undergoing inguinal hernioplasty were studied. Four different anaesthetic techniques were used: (i) surgical field infiltration (SFI) with 0.5% carbonated lidocaine + 0.125% bupivacaine (193 pts.) in which monitored anaesthesia care was administered with propofol (3 to 4 mg/kg/h) when necessary; (ii) epidural anaesthesia with 2% lidocaine + fentanyl 100 mg (137 pts.); (iii) general anesthesia with isoflurane and fentanyl in N2O:O2 (48 pts.); and (iv) intrathecal anaesthesia with 1% hyperbaric bupivacaine 1-2 ml (25 pts.). Intra- and postoperative complications, intraoperative sedation, postoperative supplemental drugs for analgesia and postoperative length of hospital stay were recorded. The data obtained were analyzed statistically using Student's t-test Anova, Bonferroni post hoc analysis, chi square, and P values less than 0.05 were considered significant. Intraoperative hypotension/brachycardia were observed in 4 patients (2%) in the SFI group and in 6 patients (4%) in the epidural group. Sedation was required in 29.5% of patients in the SFI group and in 15.3% in the epidural group (P < 0.05). Postoperative supplemental analgesic drugs administered and length of hospital stay were similar in the 4 groups. No difference in intra- and postoperative complications was observed among the 4 groups. Patients who required sedation in the SFI group were significantly more numerous than those with epidural anaesthesia. In conclusion, both SFI and epidural anaesthesia are safe and suitable for the inguinal hernioplasty procedure, without intra- or postoperative complications