Single- versus double-injection costoclavicular block: a randomized comparison.

BACKGROUND: The costoclavicular approach targets the brachial plexus in the proximal infraclavicular fossa, where the lateral, medial, and posterior cords are tightly bundled together. This randomized trial compared single- and double-injection ultrasound-guided costoclavicular blocks. We selected onset time as the primary outcome and hypothesized that, compared with its single-injection counterpart, the double-injection technique would result in a swifter onset. METHODS: Ninety patients undergoing upper limb surgery (at or below the elbow joint) were randomly allocated to receive a single- (n=45) or double-injection (n=45) ultrasound-guided costoclavicular block. The local anesthetic agent (35 mL of lidocaine 1%-bupivacaine 0.25%with epinephrine 5 µg/mL and 2 mg of preservative-free dexamethasone) was identical in all subjects. In the single-injection group, the entire volume of local anesthetic was injected between the three cords of the brachial plexus. In the double-injection group, the first half of the volume was administered in this location; the second half was deposited between the medial cord and the subclavian artery. After the performance of the block, a blinded observer recorded the onset time (defined as the time required to achieve a minimal sensorimotor composite score of 14 out of 16 points), success rate (surgical anesthesia) and block-related pain scores. Performance time and the number of needle passes were also recorded during the performance of the block. The total anesthesia-related time was defined as the sum of the performance and onset times. RESULTS: Compared with its single-injection counterpart, the double-injection technique displayed shorter onset time (16.6 (6.4) vs 23.4 (6.9) min; p<0.001; 95% CI for difference 3.9 to 9.7) and total anesthesia-related time (22.5 (6.7) vs 28.9 (7.6) min; p<0.001). No intergroup differences were found in terms of success and technical execution (ie, performance time/procedural pain). The double-injection group required more needle passes than the single-injection group (2 (1-4) vs 1 (1-3); p<0.001). CONCLUSION: Compared with its single-injection counterpart, double-injection costoclavicular block results in shorter onset and total anesthesia-related times. Further investigation is required to determine if a triple-injection technique (with targeted local anesthetic injection around each cord of the brachial plexus) could further decrease the onset time. TRIAL REGISTRATION NUMBER: NCT03595514.

Bloqueos de tronco / Truncal blocks

Truncal blocks have recently been positioned as an alternative to neuraxial analgesia. The injection of local anesthetics in interfascial planes was initially guided by anatomical landmarks, to later evolve towards a more selective administration when guided by ultrasound. Successful execution of truncal blocks requires detailed knowledge of the chest and abdominal walls anatomy. The same logic allows us to understand its potential benefits concerning perioperative analgesia, as well as its limitations and therapeutic margins. Secondary to a growing interest in less invasive techniques and analgesic techniques with a more favorable risk-benefit profile, the available evidence in this field is in continuous development. Thus, in the present review, the technical aspects of these blocks will be evaluated, emphasizing the sonoanatomy, and assessing the best evidence to support the use of each technique.

Los bloqueos de tronco se han posicionado recientemente como una alternativa frente a la analgesia neuroaxial. La inyección de anestésicos locales en planos interfasciales inicialmente fue guiado por referencias anatómicas, para posteriormente evolucionar hacia una administración más selectiva al ser guiada por el ultrasonido. La ejecución exitosa de los bloqueos de tronco requiere un conocimiento detallado de la anatomía de las paredes del tórax y abdomen. Esta misma lógica nos permite entender sus potenciales beneficios en relación con la analgesia perioperatoria, como también sus limitaciones y margen terapéutico. La evidencia disponible está en continuo desarrollo, dado el creciente interés que concitan técnicas menos invasivas y con un perfil de riesgo-beneficio potencialmente más favorable. En la presente revisión se evaluarán los aspectos técnicos de cada bloqueo, poniendo énfasis en la sonoanatomía, y evaluando la mejor evidencia que sustente el uso de cada técnica.

Effects of hyperoxia on the dynamics of skeletal muscle oxygenation at the onset of heavy-intensity exercise in patients with COPD.

This study addressed whether hyperoxia (HiOX=50% O2), compared to normoxia, would improve peripheral muscle oxygenation at the onset of supra-gas exchange threshold exercise in patients with chronic obstructive pulmonary disease (COPD) who were not overtly hypoxemic (resting Pa O2> 60 mmHg ). Despite faster cardiac output and improved blood oxygenation, HiOX did not significantly change pulmonary O2 uptake kinetics ( VO2p ). Surprisingly, however, HiOX was associated with faster fractional O2 extraction ( approximately Delta[deoxy-Hb+Mb] by near-infrared spectroscopy) (p<0.05). In addition, an "overshoot" in Delta[deoxy-Hb+Mb] was found after the initial fast response only in HiOX (7/11 patients) thereby suggesting impaired intra-muscular O2 delivery ( Q'O 2mv)-to-utilization. These data indicate that, despite improved "central" O2 delivery, Q'O2mv adapted at a slower rate than muscle VO2 under HiOX in non-hypoxaemic patients with COPD. Our results question the rationale of using supplemental O2 to improve muscle oxygenation during the transition to high-intensity exercise in this patient sub-population.