Pulse transit time as a quick predictor of a successful axillary brachial plexus block.

BACKGROUND: It can take up to 30 min to determine whether or not axillary block has been successful. Pulse transit time (PTT) is the time between the R-wave on electrocardiography (ECG) and the arrival of the resulting pressure pulse wave in the fingertip measured with photoplethysmography. It provides information about arterial resistance. Axillary block affects vasomotor tone causing loss of sympathetic vasoconstriction resulting in an increased PTT. Early objective assessment of a block can improve efficacy of operating room time and minimize patient's fear of possible conversion to general anesthesia. This study explores whether PTT can objectively, reliably and quickly predict a successful axillary block. METHODS: Forty patients undergoing hand surgery under axillary block were included. A three-lead ECG and photoplethysmographic sensors were placed on both index fingers. Measurements were made from 2 min before until 30 min after induction of the block or less if the patient was transferred for operation. Afterwards, PTT was calculated as the time between the R-wave on ECG and a reference point on the photoplethysmogram. To assess the change in PTT caused by the block, the PTT difference between the control and blocked arm was calculated. Sensitivity and specificity of PTT difference were calculated using receiver operating characteristic analysis. RESULTS: In a successful block, the mean PTT difference significantly increased after 3 min by 12 (standard error of the mean 3.9) ms, sensitivity 87% and specificity 71% (area under the curve 0.87, P = 0.004). CONCLUSIONS: PTT is a reliable, quick and objective method to assess whether axillary block is going to be successful or not.

Pilot study of the air-Q intubating laryngeal airway in clinical use.

The air-Q Intubating Laryngeal Airway (ILA) is a newly introduced extraglottic airway device. In this pilot study, we evaluated its use as a routine airway device during positive pressure ventilation. Ease of endotracheal intubation through the device was also assessed. Fifty-nine ASA I and II patients undergoing elective surgery received an air-Q ILA and an endotracheal tube where indicated. Insertion, ventilation and intubation characteristics were noted, as well as throat morbidity and occurrence of adverse events. An air-Q ILA was successfully inserted in 100% of patients. Mean leak pressure was 19 +/- 5 cmH2O. Endotracheal intubation was indicated in 19 patients and successful in 58% on the first attempt and 74% in total. Ten percent of the study patients were noted to have dysphagia. One patient was diagnosed with bilateral lingual nerve injury but made a complete recovery in four weeks. The air-Q ILA is an adequate extraglottic airway device in terms of insertion and ventilation. However the proposed advantage of ease of endotracheal intubation requires further investigation.