Use of cisatracurium during fast-track cardiac surgery
A. Ouattara1,
L. Richard1,
J. M. Charrière1,
H. Lanquetot1,
P. Corbi2 and
B. Debaene*,1
1Département dAnesthésie-Réanimation and 2Service de Chirurgie Cardio-Thoracique, Centre Hospitalier Universitaire La Milétrie, Poitiers, France*Corresponding author: Département dAnesthésie-Réanimation Chirurgicale, Centre Hospitalier Universitaire La Milétrie, 350 avenue Jacques C
ur, F-86021 Poitiers, France
Accepted for publication: August 31, 2000
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Abstract
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We prospectively studied spontaneous recovery from cisatracurium-induced neuromuscular block in 18 patients scheduled for cardiac surgery, and its suitability for fast-track cardiac surgery. Neuromuscular block was induced by an i.v. bolus (range 0.150.3 mg kg1) and maintained by a continuous infusion (range 1.13.2 µg kg1 min1) of cisatracurium until sternal closure. In the intensive care unit (ICU), spontaneous recovery was evaluated by the train-of-four (TOF) ratio measured at the adductor pollicis muscle. The ICU medical staff were unaware of the TOF ratios until sedation was stopped. At that time, if the TOF ratio was less than 0.9, sedation was recommenced. On arrival in ICU, all patients had residual paralysis. The mean time to reaching a TOF ratio of at least 0.9 was 102 min (range 74144 min) after discontinuation of the cisatracurium infusion. Fifteen patients (83%) were successfully extubated during the first 8 h after stopping the cisatracurium infusion. Only one patient showed residual paralysis when sedation was discontinued. These results support the use of cisatracurium as a suitable neuromuscular blocking agent for fast-track cardiac surgery.
Br J Anaesth 2001; 86: 1302
Keywords: neuromuscular block, cisatracurium; surgery, cardiovascular
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Introduction
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Early tracheal extubation in cardiac surgical patients reduces total cost and length of stay in the intensive care unit (ICU) without increasing the incidence of postoperative cardiorespiratory complications.1 Nevertheless, this procedure required a change in anaesthetic practice. Using a long-acting neuromuscular blocking agent such as pancuronium, Von Oldenbeek and colleagues2 reported that 65% of patients had inadequate neuromuscular function when sedation was stopped after cardiac surgery. Recently, cisatracurium besylate, a non-depolarizing neuromuscular blocking drug with an intermediate duration of action, has been recommended for use in cardiac surgery because it has no significant cardiovascular side-effects.3 As the number of elderly patients requiring cardiac surgery increases, it is appropriate to use a neuromuscular blocking drug with pharmacodynamic and pharmacokinetic properties which are minimally affected by advancing age.4 Limited data are available about the use of cisatracurium besylate during fast-track cardiac anaesthesia. The aims of this study were to investigate spontaneous recovery from cisatracurium-induced neuromuscular block after cardiac surgery, and to evaluate its suitability for use in patients undergoing early tracheal extubation after cardiac surgery.
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Methods and results
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After obtaining written informed consent, 18 patients undergoing cardiac surgery with cardiopulmonary bypass were included in this prospective study. Patients were entered into a fast-track protocol with the intent of early extubation. We defined an extubation time greater than 10 h after arrival in the ICU as delayed extubation.5 Upon arrival in the operating room, a venous catheter and an arterial catheter were inserted under local anaesthesia and routine monitoring (five lead-ECG, pulse oximeter, non-invasive arterial pressure) instituted. Anaesthesia was induced with etomidate 0.3 mg kg1, remifentanil 1 µg kg1 min1 and cisatracurium 0.150.3 mg kg1. Anaesthesia was maintained using isoflurane in oxygen/air and a continuous infusion of remifentanil 0.21.0 µg kg1 min1. The rate of the cisatracurium infusion was adjusted according to the response to stimulation of the orbicularis oculi muscle. Two surface electrodes were placed 23 cm anterior to the ear lobe. The upper branch of the facial nerve was stimulated every 15 s using train of four (TOF) supramaximal stimulation (30 mA) and the evoked responses of the orbicularis oculi muscle were estimated visually. The presence of one twitch response of the TOF at the orbicularis oculi was considered to be an adequate level of paralysis during surgery. Isoflurane end-tidal concentration and remifentanil infusion rate were adjusted according to the haemodynamic state of each patient and left to the discretion of the anaesthetist. Normothermic cardiopulmonary bypass was used in all patients. Intra-operative core temperature was recorded from nasopharyngeal and rectal probes and maintained around 35°C by using the heat exchanger on the cardiopulmonary bypass machine. Myocardial protection was achieved with intermittent antegrade blood cardioplegia. Haematocrit was maintained above 20%. The mean perfusion pressure was maintained between 50 and 70 mm Hg using isoflurane, remifentanil or norepinephrine. Additional monitoring included an end-tidal capnograph, a pulmonary arterial catheter and transoesophageal echography. The cisatracurium infusion was stopped at sternal closure.
In the ICU, patients were mechanically ventilated. Sedation was maintained with propofol 2 mg kg1 h1 and morphine 20 µg kg1 h1. Postoperative monitoring included five lead-ECG, pulse oximeter, and radial and pulmonary arterial pressures. Blood temperature was recorded by the thermistor of the pulmonary artery catheter. On arrival in ICU, neuromuscular block was evaluated by monitoring the TOF ratio using acceleromyography (TOF GUARD Organon Teknika, Turnhout-Belgium) at the adductor pollicis muscle. Supramaximal TOF stimulation (60 mA) was applied every 15 s over the ulnar nerve. The skin temperature of the thumb was monitored, and was always higher than 32°C. The ICU medical staff was blinded to the values of the TOF ratio. Only when all criteria for the discontinuation of the sedation were obtained, was the value of the TOF ratio revealed. The criteria for the discontinuation of sedation were: blood temperature higher than 37°C; haemodynamic stability; absence of significant bleeding; and absence of hypoxaemia. As previously reported,6 a TOF ratio equal to 0.9 was considered to lack of residual paralysis. Thus, the sedation was also continued until the TOF ratio reached this value. No reversal agent was administrated during the perioperative period. Spontaneous recovery times of the TOF ratio are demonstrated in Fig. 1.

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Fig 1 Spontaneous recovery profile of the TOF ratio from neuromuscular block after the end of the cisatracurium infusion. Data are means and horizontal error bars represent SD.
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On arrival in the ICU, all patients showed residual neuromuscular block (Table 1). The mean time to obtain a TOF ratio greater than 0.9 was 102 min (range 74144 min) after discontinuation of the cisatracurium infusion. Fifteen patients (83%) were successfully extubated during the first 8 h after stopping the cisatracurium infusion (mean 5 h 29 min; range between 2 h 48 min and 7 h 10 min). The mean time from arrival in ICU to extubation was 4 h 39 min (range between 2 h 00 min and 6 h 20 min). Only one patient showed residual neuromuscular block when discontinuation of sedation was proposed by the medical staff in the ICU (TOF ratio was 75%).
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Comment
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In our study, before stopping the sedation in ICU, complete recovery from cisatracurium-induced neuromuscular block (i.e. TOF ratio greater than 0.9) was achieved in all except one patient; the remainder were successfully extubated early. Thus, the use of this neuromuscular blocking agent is suitable for fast-track cardiac surgery. However, cardiac surgery was performed at normothermia in this study. As Hofmann elimination is temperature-dependent, our results may be reproducible only during normothermic cardiopulmonary bypass. A TOF ratio greater than 0.9 was used to avoid residual paralysis, as recently recommended.6 Despite the rapid recovery (mean 102 min), the profile showed large interindividual variability (range between 74 and 144 min), as previously observed when cisatracurium was infused in non-cardiac surgery patients.7 In that study, the recovery time from 5% twitch height to a TOF ratio greater than 0.7 ranged between 22 and 51 min.7 This finding confirms that quantitative neuromuscular monitoring such as acceleromyography is necessary to avoid residual paralysis after cardiac surgery, even after a non-depolarizing neuromuscular blocking drug with an intermediate duration of action has been used. This problem has been raised by Von Oldenbeek.2 Following pancuronium, the delay time from arrival in ICU to complete recovery ranged between 0 h 50 min and 8 h 15 min (mean 3 h 50 min). Additionally, their results were probably an underestimate because the value of the TOF ratio chosen as acceptable to avoid residual paralysis was 0.8 instead of 0.9 in our study.
Von Oldenbeck also reported that 13 of the 20 patients receiving pancuronium demonstrated a considerable degree of residual paralysis (median TOF 0.23) at the time sedation could be stopped.2 In our study, only one subject showed residual neuromuscular block when the ICU medical staff decided to stop sedation. The TOF ratio of this patient was 75% and reached 90%, 20 min later. The majority of our patients (83%) were extubated early. Despite the small number of patients included in our study, the frequency of early extubation was similar to previous studies (82%).1 Our results showed a long interval (mean 4 h 02 min; range between 1 h 56 min and 5 h 11 min) between return to adequate neuromuscular function and extubation. This delay confirms that recovery from paralysis is not the sole criterion for discontinuation of sedation after cardiac surgery.5
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References
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