Anesthesia & Clinical Research
Open Access

Abstract

Post-Tetanic Count Recovery after Cisatracurium in Elderly Patients

Mohammad El-Orbany, Ninos J. Joseph and M.Ramez Salem

Background: The temporal relationship between recovery of a certain post-tetanic count (PTC) and the recovery of the first twitch (T1) in the train-of-four (the PTC-T1 interval), is specific for each neuromuscular blocking drug (NMBD). A previous study reported prolongation of the PTC - T1 interval in the elderly after rocuronium. The ability to accurately predict the return of T1 is an important component of PTC monitoring since it may affect clinical decisions about administration versus withholding a maintenance dose of the NMBD. This study was designed to evaluate PTC recovery from intense cisatracurium-induced NMB in geriatrics and investigate its relationship with T1.

Methods: After IRB approval, Thirty-two patients who are older than 65yr were recruited and the informed consent signed. After anesthesia induction, neuromuscular monitoring was performed using acceleromyography. Cisatracurium 0.15 mg/kg was administered and tracheal intubation performed when the response to TOF stimulation was abolished. Cycles of post- tetanic stimulation were applied every 6 minutes with TOF monitoring in between. Anesthesia was maintained with propofol infusion and nitrous oxide in oxygen 60:40. Measurements included time to reappearance, and number of PTC, time to T1, and the number of PTC when T1 was imminent. The correlation between PTC and T1 was also studied.

Results: 32 subjects were studied 32. The mean time needed for the first response to post-tetanic stimulation (PTC1) to appear was 34.4 ± 5.5 minutes and the mean time needed for T1 to reappear was 45.7 ± 5.8 minutes. The median number of detectable PTC just before or coinciding with T1 appearance was 9. There was a strong correlation between the number of detectable PTC and time to T1 appearance (Correlation coefficient 0.929).

Conclusions: There is a consistent temporal relationship between the number of PTC and the time to T1 recovery after cisatracurium in elderly patients. This may allow more accurate control and predictable recovery from intense cisatracurium-induced block in the elderly.