Novel external oblique muscle plane block for blockade of the lateral abdominal wall: a pilot study on volunteers.

PURPOSE: No reports have described techniques to efficiently anesthetize the lateral cutaneous branches of the entire abdomen. The aim of this study was to investigate an effective procedure for blocking the lateral cutaneous branches in the abdominal region. We sought to describe the sensory distribution of the previously described thoracoabdominal nerve block through perichondrial approach (TAPA) and the novel costal and lateral external oblique muscle plane (EXOP) blocks in healthy volunteers. METHODS: This was a proof-of-concept pilot study that comprised ten volunteers with an American Society of Anesthesiologists Physical Status I. The participants underwent modified TAPA (M-TAPA), injection 2 of TAPA (injection into the anterior aspect of the 10th costal cartilage: I2-TAPA), costal EXOP, and lateral EXOP blocks with injection of 20 mL of ropivacaine 0.2% for each block. A pinprick test was performed one hour after injection and repeated at 30-min intervals until the effect of the nerve block disappeared. RESULTS: The M-TAPA injection anesthetized the anterior branches from T6/7 to T11/12, whereas the I2-TAPA injection had no effect. Costal and lateral EXOP injections anesthetized the lateral cutaneous branches of T7-10 and T11-12, respectively. CONCLUSION: The results of this pilot study in ten healthy volunteers indicate that novel EXOP blocks involving local anesthetic injection superficial to the external oblique muscle efficiently anesthetize the lateral cutaneous branches of the thoracoabdominal nerves. Our study shows that it may be anatomically plausible for the combined use of these blocks to anesthetize the entire abdominal wall.

RéSUMé: OBJECTIF: Aucune présentation de cas n'a décrit de techniques permettant l'anesthésie efficace des branches cutanées latérales de tout l'abdomen. L'objectif de cette étude était d'évaluer une procédure efficace pour bloquer les branches cutanées latérales de la région abdominale. Nous avons cherché à décrire la distribution sensorielle du bloc nerveux thoraco-abdominal par approche périchondrale (TAPA), décrit précédemment, et des nouveaux blocs du plan musculaire oblique externe (EXOP) costal et latéral réalisés chez des volontaires sains. MéTHODE: Il s'agissait d'une étude pilote de preuve de concept qui comprenait dix volontaires avec un statut physique I selon l'American Society of Anesthesiologists. Les participants ont bénéficié d'un bloc TAPA modifié (M-TAPA), de l'injection 2 d'un bloc TAPA (injection dans l'aspect antérieur du 10e cartilage costal : I2-TAPA), d'un bloc EXOP costal et d'un bloc EXOP latéral avec injection de 20 mL de ropivacaïne 0,2 % pour chaque bloc. Un test cutané par piqûre d'épingle a été réalisé une heure après l'injection et répété à des intervalles de 30 minutes jusqu'à ce que l'effet du bloc nerveux disparaisse. RéSULTATS: L'injection de M-TAPA a anesthésié les branches antérieures de T6/7 à T11/12, tandis que l'injection d'I2-TAPA n'a eu aucun effet. Les injections costales et latérales d'EXOP ont anesthésié les branches cutanées latérales de T7­10 et T11­12, respectivement. CONCLUSION: Les résultats de cette étude pilote chez dix volontaires sains indiquent que les nouveaux blocs EXOP avec une injection superficielle d'anesthésique local au muscle oblique externe anesthésient efficacement les branches cutanées latérales des nerfs thoraco-abdominaux. Notre étude montre qu'il peut être anatomiquement plausible de combiner ces blocs pour anesthésier toute la paroi abdominale.

[Two Cases of Tension Pneumothorax during Posterior Spinal Fusion -Diagnosis and Decision on Emergency Drainage-].

We experienced two cases of tension pneumothorax during posterior spinal fusion. Case 1 : A 67-year-old female underwent posterior thoracic-lumbar spinal fusion. One hour after the operation had started, a sudden elevation of airway pressure and decreased Pa02 were observed. Then occasional decrease in blood pressure, tachycardia, and premature ventricular contractions followed. SpO2 re- mained stable throughout the surgery. Case 2 : A 57-year-old female underwent posterior thoracic-lumbar spinal fusion. During the surgical pro- cedure, a sudden decrease in SpO2 accompanied by an air leak from pleura occurred. No remarkable change was observed in hemodynamics. Immediately after the operation had finished, chest X-ray on supine position revealed tension pneumotho- rax in both cases. Patients were extubated after effec- tive lung expansion by insertion of thoracic drainage tube. Tension pneumothorax is a potentially lethal compli- cation during anesthesia, resulting in cardiac arrest Though rapid diagnosis is crucial, physical examination and assessment are limited in patients on prone posi- tion. The possibility must be considered that several conditions as increased airway pressure, impaired oxy- genation and hemodynamics suggest tension pneumo- thorax. Image diagnosis using radiography or ultra- sound can be of value. If once patient on prone position develops cardiac arrest, resuscitation is extremely difficult Emergency drainage should be considered in case of highly im- paired hemodynamics.