P030: LAST DURING AN AWAKE TRACHEOSTOMY
Katherine Medrano, MD; Gabriella Sardina, MD; Kalina Nedeff, MD; Nicholas Nedeff, MD; HCA Kendall Regional Medical Center
A 67-year old male was diagnosed with squamous cell carcinoma, which rapidly progressed to airway obstruction requiring an emergency awake tracheostomy. Superficial cervical fascia blocks were performed bilaterally using plain 3% lidocaine. Soon after the administration of the local anesthetic the patient developed tonic-clonic seizures followed by cardiorespiratory arrest requiring one round of cardiopulmonary resuscitation. Once ROSC was achieved the patient was placed on intralipid infusion per LAST protocol. The patient underwent tracheostomy under general anesthesia with an ETT and remained on mechanical ventilation until fully recovering his mental status.
LAST is always a potential complication, and may occur with all LAs, and any route of administration. LAST primarily affects the central nervous system and cardiovascular system, and may be fatal. Major LAST events are reported in 0.04 to 1.8/1000 peripheral nerve blocks. The majority of reported cases of LAST have occurred after inadvertent intravenous (IV) injection of LA. However, systemic absorption from LA administration sites can also cause toxic blood levels, and may cause a delayed, gradual onset of symptoms and signs.
Injection of LA in highly vascular sites can increase the risk of direct intravascular injection and systemic absorption of LA. Regional anesthesia procedures that target particularly vascular sites include (in order of decreasing risk) intercostal blocks> caudal and epidural anesthesia> interfascial plane blocks of the abdominal wall> psoas compartment blocks> sciatic blocks> and cervical and brachial plexus blocks.
LAST occurs soon after injection of LA, and progresses through central nervous system excitation, central nervous system (CNS) inhibition, cardiovascular excitation, and in extreme cases, cardiovascular inhibition and arrest. However, in a review of 93 reported LAST events that occurred during regional anesthesia over 30 years until 2009, only 60 percent of reported cases followed this classic presentation.