Non-depolarizing neuromuscular blockers (nNMBs) are administered as primary therapy in facilitating endotracheal intubations and adjuvant therapy in the perioperative maintenance of anesthesia and care of the critically ill patient. Primarily nNMBs (rocuronium, vecuronium, pancuronium, atracurium, cisatracurium, mivacurium) are used to facilitate airway management and decrease the risk of laryngeal injury during regular and emergent intubations.[1] nNMBs can decrease hoarseness secondary to intubation via decreasing incidence of vocal cord injuries.[2] As an adjunctive therapy to intravenous (IV) or inhaled anesthetics, nNMBs has also been found to improve outcomes of mechanical ventilation in patients with poor lung compliance who are critically ill and/or being treated in the perioperative setting.[3] This combination in the perioperative setting can also facilitate access to the thoracic and abdominal cavities by depressing voluntary or reflex muscle movement.[4]

Patients with pre-excitation abnormalities are at a high risk for life-threatening perioperative arrhythmias. In Wolff-Parkinson-White syndrome, the anaesthetics used for invasive diagnostic testing/ablation, should not affect cardiac electrophysiology; propofol, sevoflurane, fentanyl, sufentanil, alfentanil are suitable. In non-ablative surgery, propofol, sevoflurane, isoflurane, fentanyl, alfentanil, sufentanil have been used safely. Among neuromuscular blockers, cis-atracurium, rocuronium and vecuronium are good choices. Ketamine, pancuronium and pethidine should be avoided because of their sympathomimetic actions. Anticholinergic/ anticholinesterase combinations for neuromuscular block reversal should preferably be omitted, while sugammadex seems more attractive. In regional anaesthesia, addition of epinephrine and high sympathetic blocks should be avoided. Hypotension should be treated with pure alpha-adrenergic agonists. Other pre-excitation abnormalities associated with different accessory pathways are the Mahaim Fiber and Lown-Ganong-Levine syndrome. Sympathetic activation should be avoided. Total intravenous anaesthesia with propofol probably represents the safest option. A careful anaesthetic plan and close cooperation with cardiologists are mandatory for successful management.

A 52-year-old patient was scheduled for a cystoscopy. Anesthesia was induced by intravenous injection of fentanyl and propofol. After administration of atracurium, he became bradycardic and suffered a cardiac arrest. Despite prolonged cardiopulmonary resuscitation, the patient could not be revived. Electrolytes and hemoglobin levels were normal, and a transthoracic echocardiogram showed no signs of pericardial effusions or of any left ventricular contraction. The postmortem found no pathology. However, mast cell tryptase was raised significantly, indicating fatal anaphylaxis. Having presented no classic clinical signs, this case is a reminder that rapid cardiovascular collapse can be the sole clinical feature of anaphylaxis.

Neuromuscular blocking agents should be included as part of a balanced anaesthetic protocol to improve anaesthetic management, although doses are not always established for each species. Cis-atracurium is a benzylisoquinolinium neuromuscular blocking agent with an intermediate duration of action devoid of significant adverse effects previously used in pigs with a wide dosage range. Cis-atracurium was administered at 1 mg/kg bolus to sixteen pigs to establish its time profile and effects. The pigs were premedicated intramuscularly with 4 mg/kg azaperone, 8 mg/kg ketamine and 0.2 mg/kg morphine IM and maintained with isoflurane in oxygen. After cis-atracurium administration, neuromuscular monitoring via acceleromyography was started until the recovery of the 90% of the train of four ratio. Complete decrease in the train of four ratio was accomplished in eleven pigs. Onset of action was 70 s, with a recovery of the fourth twitch at 26 min and a recovery of a train of four ratio greater than 90% in 60 min. In conclusion, 1 mg/kg intravenous cis-atracurium in the pig allowed for a rapid onset of action and a complete recovery after 60 min although high variability in the time profile is seen.

No information is available on the use of atracurium during breastfeeding. Because it is short acting, highly polar and poorly absorbed orally, it is not likely to reach the breastmilk in high concentration or to reach the bloodstream of the infant.[1][2] When a combination of anesthetic agents is used for a procedure, follow the recommendations for the most problematic medication used during the procedure.

Neuromuscular blocking agents (NMBAs) are commonly used in experimental laparoscopy in swine undergoing carbon dioxide pneumoperitoneum. Hypercapnia may be present and may prolong NMBAs' pharmacologic activity. The aim of this study is to evaluate the effect of permissive hypercapnia on the neuromuscular blockade of atracurium in swine. Six Large White swine weighing 30.5 ± 1.6 kg were sedated with intramuscular ketamine and medetomidine, after which anaesthesia was induced with propofol and maintained with sevoflurane. Atracurium 0.4 mg/kg was administered intravenously and the neuromuscular block monitored by acceleromyography during normocapnic and hypercapnic conditions (PaCO2 range 35-45 mmHg and 60-70 mmHg, respectively). Onset time and time to reach a train of four ratio (TOFR) of 0.7 and 0.9 were recorded. Cardiorespiratory parameters, electrolytes and acid-base status were measured under both conditions. Onset time was similar between the two conditions. Time to reach a TOFR of 0.7 and 0.9 (duration of the neuromuscular block) was longer in hypercapnic compared to normocapnic animals being 1325 ± 300 vs 855 ±111 (p = 0.002) and 1823 ± 434 vs 1218 ± 210 seconds (p = 0.005), respectively. Three hypercapnic swine had a TOF count of 2 and 1 instead of a count of 4 with fade. Permissive hypercapnia was associated with a decrease in pH from 7.444 ± 0.039 to 7.257 ± 0.025 (p < 0.001). No differences were observed for heart rate, end-tidal concentration of sevoflurane, body temperature and arterial haemoglobin saturation. Nonetheless, hypercapnic swine had a statistically significant increase in mean arterial pressure (p = 0.020) and plasma potassium concentration (p = 0.003). The values of PaCO2 achieved during hypercapnia were well tolerated in swine undergoing CO2 pneumoperitoneum for laparoscopy. Permissive hypercapnia increased the duration of the atracurium effect and caused an increase in the intensity of the neuromuscular block in few swine.

  Walruses are a challenging species to anesthetize as a result of their large mass, limited access for drug delivery, unique physiology, and small number of reports describing anesthetic procedures. Three aquarium-housed walruses ( Odobenus rosmarus) ranging in age from 3 to 11 yr old (344-1,000 kg) were anesthetized for dental or ophthalmic surgical procedures, with one animal anesthetized twice and one anesthetized three times. Preanesthetic medication was with intramuscular midazolam (0.1-0.2 mg/kg) and meperidine (2-3 mg/kg). A catheter was placed in the extradural intravertebral vein, and anesthesia was induced with propofol to effect. Orotracheal intubation was performed and anesthesia maintained with isoflurane in oxygen using a circle breathing system connected to a ventilator. Intermittent positive pressure ventilation was used in all procedures. For the ophthalmic surgery, the neuromuscular blocking agent, cisatracurium, was given intravenously to provide a central eye and optimal surgical conditions. The neuromuscular block was antagonized with edrophonium. Total anesthesia times ranged from 1.5 to 6 hr. Midazolam and meperidine were antagonized with flumazenil and naltrexone, respectively, in five of six cases. Nonsteroidal anti-inflammatory agents were provided for analgesia. Recoveries were calm and uneventful. The described anesthetic protocols and case management were successful under the conditions encountered.