Regarding the paper published "Erector spinae plane block: Anatomical landmark-guided technique".

Sir,

We read with great interest the article by Tuhin et al. titled “Erector spinae plane block: Anatomical landmark- guided technique”.[1] Authors have explained administration of erector spinae plane block (ESPB) using newer technique with the help of anatomical landmarks. The novel interfascial plane blocks like ESPB was originally explained by Forero et al. using ultrasound in cases of severe neuropathic pain.[2] They have used ESPB in a patient with multiple lytic lesions of left fifth and sixth ribs and rapidly enlarging soft tissue mass around the lesion in left sixth rib from primary bladder carcinoma resulting in left sided severe multidermatomal neuropathic pain. The local anaesthetic (LA) was given at the site of patient's primary trigger area for pain, 3 cm lateral to T5 spinous process. Full assessment of extent of sensory block performed 2 hours after giving block revealed area of diminished sensation to pinprick extending from T2 to T9 in cephalocaudad direction, and from a line 3 cm lateral to thoracic spine to midclavicular line in an anterior–posterior direction. In another patient with neuropathic pain due to malunion of multiple rib fractures, LA was given 3 cm lateral to midline at tips of T5 transverse process deep to erector spinae muscle to deposit it closer to dorsal and ventral rami. ESPB given by Forero et al. in different patients is ultrasound guided at level of T5 and 3 cm from midline to target transverse process. Further, Forero et al. described transverse processes as convenient sonographic landmark and backstop for needle advancement, contributing to ease, simplicity and safety of the block.[2] However, an attempt to accurately target transverse process of T5 without ultrasound guidance is challenging. The distance between transverse and spinous process may not necessarily be 3 cm in every patient. The distance between two processes will depend on built of patient. Different methods like the “Rule of threes”[3] or “Geelhoed's rule”[3] have been used to determine anatomical relationship between thoracic spinous and transverse processes but none has been mentioned by authors for palpation of transverse process while using this anatomical landmark for administering ESPB. Moreover, depth of transverse process can be more variable than 2-4 cm depending on built of patient. Since the location of transverse process varies as it is not fixed, the technique mentioned by authors i.e. 3 cm from midline and at depth of 2-4 cm may lead to pleural puncture and possible complication of pneumothorax. Recently, one case of pneumothorax has been reported even with ultrasound guided ESPB.[4] Nevertheless, advancing needle while visualizing anatomical structures during administering of ESPB is safer than advancing needle blindly after palpation of landmarks. The characteristic “safety” of ESPB is due to easily recognizable sonoanatomy and absence of structures at risk of needle injury in immediate vicinity can be lost if block is performed without using ultrasound. The use of loss of resistance technique to reach different fascial planes is also difficult.[5] The application of loss of resistance technique used for giving abdominal fascial plane blocks using blunt or short-bevelled needles which provide a good feedback (pops or clicks) when they pass through fascial planes for administering thoracic fascial plane blocks is questionable.[5] Though resources are limited and ultrasound machines are not available in every hospital but we should be cautious while using techniques that have been originally described using ultrasound and keep in mind the complications that can result without using ultrasound. The availability of ultrasound has increased over past decade with increase in application of ultrasound in clinical anaesthesia practice. Till there is availability of ultrasound in all settings, use of traditional methods using intravenous analgesics and neuraxial anaesthesia techniques is a safer option to provide adequate analgesia without compromising patient care.

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