A randomized crossover comparison between the Laryngeal Mask Airway-Unique™ and the air-Q intubating laryngeal airway in children.

OBJECTIVES: The purpose of this randomized crossover study was to evaluate the feasibility of the air-Q intubating laryngeal airway (ILA) in clinical practice when compared with the Laryngeal Mask Airway-Unique(™) (LMA-U), the current standard of care for primary airway maintenance. AIM: We hypothesized that the ILA would have better airway seal pressures and laryngeal alignment than the LMA-U in anesthetized nonparalyzed children. BACKGROUND: The ILA is a newer supraglottic airway for children with design features that allow it to be used for primary airway maintenance and as a conduit for tracheal intubations. METHODS: Fifty healthy children, 6-36 months of age, 10-15 kg, who were scheduled for elective surgery in which the use of a size two LMA-U and size 1.5 ILA would be appropriate for airway maintenance, were enrolled into this randomized crossover study. Primary outcome measures were airway leak pressures and fiberoptic grades of view. Secondary outcome measures included ease and time for successful insertion, incidence of gastric insufflation, ventilation parameters, and complications. RESULTS: There were no statistically significant differences in regard to the ease of device insertion, time to ventilation, gastric insufflation, and ventilation parameters between the ILA and the LMA-U. All devices were successfully placed on the first attempt, and there were no instances of failure. There were statistically significant differences in the airway leak pressure between the ILA (19.0 ± 5.4 cmH(2)O) and the LMA-U (16.1 ± 4.9 cmH(2)O), P = 0.001. There were also statistically significant differences in the fiberoptic grades of view between the ILA and LMA-U, P = 0.004. CONCLUSIONS: The ILA had higher airway leak pressures and superior fiberoptic grades of view when compared with the LMA-U and can be a suitable alternative to the LMA-U in children weighing 10-15 kg.

Prospective evaluation of the self-pressurized air-Q intubating laryngeal airway in children.

OBJECTIVES: To assess the clinical efficacy of the self-pressurized air-Q ILA™ (ILA-SP). AIM: The purpose of this prospective audit was to evaluate the feasibility of the ILA-SP in clinical practice and generate data for future comparison trials. BACKGROUND: The ILA-SP is a new first-generation supraglottic airway for children with a self-adjusting cuff and lack of a pilot balloon. METHODS: Over a 4-month period, 352 children with an ASA physical status of I-III, newborn to 18 years of age, undergoing various procedures were studied. Data points assessed included insertion success rates, airway leak pressures, quality of ventilation, and perioperative complications associated with the use of this device. RESULTS: In 349 of the 352 patients in this study, the ILA-SP was used successfully as a primary supraglottic airway device in a variety of patients. Three patients required conversion to a standard laryngeal mask airway or a tracheal tube. The mean initial airway leak pressure for all patients was 17.8 ± 5.4 cm H(2)O, and 20.4 ± 5.5 cm H(2)O when re-checked at 10 min, which was statistically significant (P < 0.001). Complications were limited to 14 patients and related to reflex activation of the airway (coughing, laryngospasm, and bronchospasm) (n = 10), sore throat (n = 3), and blood staining on removal of the device (n = 1). There were no episodes of regurgitation, aspiration, or hoarseness. CONCLUSIONS: Acceptable clinical performance was demonstrated with the ILA-SP for a variety of procedures in infants and children with spontaneous and positive pressure ventilation. Future studies comparing this device to other supraglottic airways may provide useful information regarding the safety of the ILA-SP in pediatric clinical practice.

A clinical evaluation of the intubating laryngeal airway as a conduit for tracheal intubation in children.

BACKGROUND: The air-Q Intubating Laryngeal Airway (ILA) (Cookgas LLC, Mercury Medical, Clearwater, FL) is a supraglottic airway device available in pediatric sizes, with design features to facilitate passage of cuffed tracheal tubes when used to guide tracheal intubation. We designed this prospective observational study of the ILA to assess the ease of its placement in paralyzed pediatric patients, determine its position and alignment to the larynx using a fiberoptic bronchoscope, gauge its efficacy as a conduit for fiberoptic intubation with cuffed tracheal tubes, and evaluate the ability to remove the ILA without dislodgement of the tracheal tube after successful tracheal intubation. METHODS: One hundred healthy children, aged 6 months to 8 years, ASA physical status I to II, and scheduled for elective surgery requiring general endotracheal anesthesia were enrolled in this prospective study. Based on the manufacturer's guidelines, each patient received either a size 1.5 or 2.0 ILA according to their weight. The number of attempts for successful insertion, leak pressures, fiberoptic grade of view, number of attempts and time for tracheal intubation, time for ILA removal, and complications were recorded. RESULTS: ILA placement, fiberoptic tracheal intubation, and ILA removal were successful in all patients. The size 1.5 ILA cohort had significantly higher rates of epiglottic downfolding compared with the size 2.0 ILA cohort (P < 0.001), despite adequate ventilation variables. When comparing fiberoptic grade of view to weight, a moderate negative correlation was found (r = -0.41, P < 0.001), indicating that larger patients tended to have better fiberoptic grades of view. The size 1.5 ILA cohort had a significantly longer time to intubation (P = 0.04) compared with the size 2.0 ILA cohort. However, this difference may not be clinically significant because there was a large overlap of confidence bounds in the average times of the size 1.5 ILA (27.0 ± 13.0 seconds) and size 2.0 ILA cohorts (22.7 ± 6.9 seconds). When comparing weight to time to tracheal intubation, a weak correlation that was not statistically significant was found (r = -0.17, P = 0.09), showing that time to intubation did not differ significantly according to weight, despite higher fiberoptic grades in smaller patients. CONCLUSIONS: The ILA was easy to place and provided an effective conduit for tracheal intubation with cuffed tracheal tubes in children with normal airways. Additionally, removal of the ILA after successful intubation could be achieved quickly and without dislodgement of the tracheal tube. Because of the higher incidence of epiglottic downfolding in smaller patients, the use of fiberoptic bronchoscopy is recommended to assist with tracheal intubation through this device.

The effect of motor activity on the onset and progression of brachial plexus block with bupivacaine: a randomized prospective study in patients undergoing arthroscopic shoulder surgery.

BACKGROUND: A decreased latency of onset of neural blockade has been noted when muscular exercise of the hand was performed after supraclavicular brachial plexus block using lidocaine. In this observational study, we examined the effect of repetitive muscle contraction of the hand on the speed of onset of interscalene brachial plexus block (ISB) using bupivacaine. METHODS: Forty patients were enrolled, all of whom received an ISB as one component of their anesthetic management for elective arthroscopic shoulder surgery. Patients were asked either to rest their arms after the performance of the ISB (nonexercise group) or to perform a repetitive hand exercise for 5 min (exercise group). Bilateral hand grip strength and tolerance to transcutaneous electrical stimulation were used to quantify the degree of motor and sensory blockade. RESULTS: Patients in the exercise group had a statistically significant lower tolerance to transcutaneous electrical stimulation 20 min after completion of the block (P < 0.05). CONCLUSIONS: Our results imply that attempting to use a frequency-dependent conduction block with repetitive motor activity as a clinical adjuvant to brachial plexus block with bupivacaine is without merit.

Intrathecal magnesium sulfate administration at the time of experimental ischemia improves neurological functioning by reducing acute and delayed loss of motor neurons in the spinal cord.

BACKGROUND: In this study, the authors determined the effect of magnesium sulfate on intrathecal glutamate concentrations, hindlimb motor function, and histopathology after a transient episode of spinal cord ischemia. METHODS: Fifty-two New Zealand White rabbits underwent spinal cord ischemia for 30 min. Fifteen minutes before ischemia, animals received intrathecal magnesium sulfate (MgSO4) (3 mg/kg) or placebo (artificial cerebrospinal fluid). Intrathecal microdialysis samples were measured for glutamate using high-performance liquid chromatography. Neurologic function and spinal cord histopathology were assessed throughout the recovery period. RESULTS: Intrathecal glutamate levels in placebo-treated animals were higher after spinal cord ischemia compared with sham- and MgSO4-treated animals. MgSO4-treated animals had increased lower extremity motor function compared with the placebo group (64.7% vs 14.3%, P < 0.01). Histologic examination of placebo-treated animals revealed significant motor neuron cell loss at thoracolumbar levels by Day 7 (P < 0.05), whereas lower lumbar regions displayed significant neuron loss on Day 1. Spinal cords from MgSO4-treated animals exhibited less neuronal loss in lumbar regions. Similar effects were present in the thoracolumbar segments on Day 7. A significant correlation existed between diminished neuronal loss and hind leg movement (Tarlov score) and demonstrates that the neurologic outcome after MgSO4 treatment was related to lower lumbar ventral horn cell survival (r2 = 0.812, P < 0.001). CONCLUSIONS: These results demonstrate that MgSO4 affords significant spinal cord motor neuron protection by diminishing acute neuronal loss at the foci of the ischemic injury (L3-L6) with delayed neuronal degeneration in adjacent spinal cord regions (T7-L2).