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Monitoring of Intense Neuromuscular Blockade Caused by Atracurium
Br. J. Anaesth. (1986), 58, 68S
MONITORING OF INTENSE NEUROMUSCULAR BLOCKADE CAUSED BY ATRACURIUM
Department of Anaesthesia, King Khalid University Hospital, Riyadh, Saudi Arabia
The short duration of action and rapid recovery rate of the new non-depolarizing neuromuscular blocking agents atracurium and vecuronium have increased the need for reliable methods to assess objectively the degree of neuromuscular blockade. The ability to predict, well in advance, the time for clinical recovery would ensure precise timing of incremental doses and hence smooth neuromuscular blockade. Mechanical response to single twitch, tetanic and train-of-four (TOF) nerve stimulation are often used to assess recovery from neuromuscular blockade (AH and Savarese, 1976). During intense blockade, there is no response to these modes of stimulation and the degree of blockade therefore cannot be established. However, using the longacting neuromuscular blocking agent pancuronium, it is possible to quantify part of this so called "period of no response" by applying tetanic stimulations (50 Hz for 5 s) followed by single twitch (1 Hz) stimulations. The number of responses to the post-tetanic single twitch stimulation is called the post-tetanic count or PTC (Viby-Mogensen et al., 1981). A close correlation between PTC and recovery from intense neuromuscular blockade caused by pancuronium has been found (Howardy-Hansen et al., 1984). The object of this study was to clarify whether a similar correlation exists between PTC recovery from blockade caused by atracurium. Atracurium-induced intense neuromuscular
blockade was evaluated in 60 randomly selected patients using PTC and TOF methods. Thirty patients were anaesthetized with thiopentone, nitrous oxide and halothane and 30 patients received thiopentone, nitrous oxide and fentanyl. In all patients a close correlation was found between the number of the PTC and the time of onset of the TOF response. A PTC of 0 indicated that the time to first response to TOF stimulation was always more than 8 min. A PTC of 1 meant that the TOF response would appear in, on average, 9 min (95 % confidence limits: 4-14 min). Halothane significantly prolonged the time from injection of atracurium to the first response to post-tetanic single twitch stimulation. It is concluded that the relationship between PTC and the time to first response to TOF nerve stimulation makes the PTC method a valuable supplement to TOF nerve stimulation for neuromuscular monitoring during clinical anaesthesia involving atracurium. REFERENCES Ali, H. H., and Savarese, J. J. (1976). Monitoring of neuromuscular function. Arwihesiology, 45, 216. Howardy-Hansen, P., Viby-Mogensen, J., Gortschau, A., Skovgaard, L. T., Chraemmer-Jorgensen, B., and Engbaek, J. (1984). Tactile evaluation of the post-tetanic count (PTC). Amsthtsiolagy, 60, 372. Viby-Mogensen, J., Howardy-Hansen, P., Chraemmer-Jorgensen, B., Ording, H., Engbaek, J., and Nielsen, A. A. (1981). Post-tetanic count (PTC): A new method of evaluating an intense neuromuscular blockade. Aiwthesiology, 60, 372.
Downloaded from http://bja.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on July 2, 2015
J. VIBY-MOGENSEN, A. K. BONSU, P. U. E. FERNANDO, K. MUCHHAL, A. TAMILARASAN AND A. LAMBOURNE
MONITORING OF INTENSE NEUROMUSCULAR BLOCKADE CAUSED BY ATRACURIUM
Department of Anaesthesia, King Khalid University Hospital, Riyadh, Saudi Arabia
The short duration of action and rapid recovery rate of the new non-depolarizing neuromuscular blocking agents atracurium and vecuronium have increased the need for reliable methods to assess objectively the degree of neuromuscular blockade. The ability to predict, well in advance, the time for clinical recovery would ensure precise timing of incremental doses and hence smooth neuromuscular blockade. Mechanical response to single twitch, tetanic and train-of-four (TOF) nerve stimulation are often used to assess recovery from neuromuscular blockade (AH and Savarese, 1976). During intense blockade, there is no response to these modes of stimulation and the degree of blockade therefore cannot be established. However, using the longacting neuromuscular blocking agent pancuronium, it is possible to quantify part of this so called "period of no response" by applying tetanic stimulations (50 Hz for 5 s) followed by single twitch (1 Hz) stimulations. The number of responses to the post-tetanic single twitch stimulation is called the post-tetanic count or PTC (Viby-Mogensen et al., 1981). A close correlation between PTC and recovery from intense neuromuscular blockade caused by pancuronium has been found (Howardy-Hansen et al., 1984). The object of this study was to clarify whether a similar correlation exists between PTC recovery from blockade caused by atracurium. Atracurium-induced intense neuromuscular
blockade was evaluated in 60 randomly selected patients using PTC and TOF methods. Thirty patients were anaesthetized with thiopentone, nitrous oxide and halothane and 30 patients received thiopentone, nitrous oxide and fentanyl. In all patients a close correlation was found between the number of the PTC and the time of onset of the TOF response. A PTC of 0 indicated that the time to first response to TOF stimulation was always more than 8 min. A PTC of 1 meant that the TOF response would appear in, on average, 9 min (95 % confidence limits: 4-14 min). Halothane significantly prolonged the time from injection of atracurium to the first response to post-tetanic single twitch stimulation. It is concluded that the relationship between PTC and the time to first response to TOF nerve stimulation makes the PTC method a valuable supplement to TOF nerve stimulation for neuromuscular monitoring during clinical anaesthesia involving atracurium. REFERENCES Ali, H. H., and Savarese, J. J. (1976). Monitoring of neuromuscular function. Arwihesiology, 45, 216. Howardy-Hansen, P., Viby-Mogensen, J., Gortschau, A., Skovgaard, L. T., Chraemmer-Jorgensen, B., and Engbaek, J. (1984). Tactile evaluation of the post-tetanic count (PTC). Amsthtsiolagy, 60, 372. Viby-Mogensen, J., Howardy-Hansen, P., Chraemmer-Jorgensen, B., Ording, H., Engbaek, J., and Nielsen, A. A. (1981). Post-tetanic count (PTC): A new method of evaluating an intense neuromuscular blockade. Aiwthesiology, 60, 372.
Downloaded from http://bja.oxfordjournals.org/ at University of Iowa Libraries/Serials Acquisitions on July 2, 2015
J. VIBY-MOGENSEN, A. K. BONSU, P. U. E. FERNANDO, K. MUCHHAL, A. TAMILARASAN AND A. LAMBOURNE