Duration of action
Neuromuscular-blocking agents can be classified in accordance to their duration of pharmacological action, defined as follows:

Side effects
Cardiovascular
The tetrahydroisoquinolinium class of neuromuscular blocking agents, in general, is associated with histamine release upon rapid administration of a bolus intravenous injection. There are some exceptions to this rule; e.g., cisatracurium (Nimbex) is one such agent that does not elicit histamine release even up to 5xED95 doses. The liberation of histamine is a dose-dependent phenomenon such that, with increasing doses administered at the same rate, there is a greater propensity for eliciting histamine release and its ensuing sequelae. Most commonly, the histamine release following administration of these agents is associated with observable cutaneous flushing (facial face and arms, commonly), hypotension and a consequent reflex tachycardia. These sequelae are very transient effects: The total duration of the cardiovascular effects is no more than one to two minutes, while the facial flush may take around 3–4 minutes to dissipate. Because these effects are so transient, there is no reason to administer adjunctive therapy to ameliorate either the cutaneous or the cardiovascular effects. Bronchospasm
Bronchospasm has been reported on occasion with the use of atracurium. However, this particular undesirable effect does not appear to be observed nearly as often as that seen with rapacuronium, which led to the latters withdrawal of approval for clinical use worldwide.
Erotic asphyxiation (variously called asphyxiophilia, hypoxyphilia or breath control play) is the intentional restriction of oxygen to the brain for the purposes of sexual arousal. The term autoerotic asphyxiation is used when the act is done by a person to themselves. Colloquially, a person engaging in the activity is sometimes called a gasper. Erotic asphyxiation can lead to accidental death due to asphyxia. The erotic interest in asphyxiation is classified as a paraphilia in the Diagnostic and Statistical Manual of the American Psychiatric Association. Physiology
Concerning hallucinogenic states brought about by chronic hypoxia, Dr. E. L. Lloyd notes that they may be similar to the hallucinations experienced by climbers at altitude. He further notes that no such state occurs in hypoxia brought about by sudden aircraft decompression at altitude. These findings suggest to him that they do not arrive purely from a lack of oxygen. Upon examining the studies on hypoxia he found that "abnormalities in the cerebral neurochemistry involving one or more of the interconnected neurotransmitters, dopamine, serotonin, and beta-endorphin had been reported in all the conditions associated with hallucinations." History
Historically, the practice of autoerotic asphyxiation has been documented since the early 17th century. It was first used as a treatment for erectile dysfunction. The idea for this most likely came from subjects who were executed by hanging. Observers at public hangings noted that male victims developed an erection, sometimes remaining after death (a death erection), and occasionally ejaculated when being hanged.