sugammadex, although its onset is much slower. it works by competitively inhibiting acetylcholinesterase, an enzyme that breaks down acetylcholine. this results in an accumulation of acetylcholine present in the neuromuscular junction, effectively reversing the paralysis of the patient. the dosage is between 0.03 and 0.07 mg/kg. a common side effect of this drug is bradycardia. therefore, glycopyrrolate, an anticholinergic drug, should be given immediately prior to neostigmine to prevent bradycardia. other medications thiopental metaraminol or ephedrine, where hypotension may occur secondary to the sedating drugs. phenylephrine – this drug is administered to those with hypotension post intubation as a result of lidocaine, midazolam, fentanyl, propofol, and ketamine. the dosages range from 50 to 200 μg in adults. it has quick onset and quick elimination. the common side effect is reflex bradycardia. pre-intubation steps rapid sequence intubation refers to the pharmacologically induced sedation and neuromuscular paralysis prior to intubation of the trachea. the technique is a quicker form of the process normally used to induce general anesthesia. a useful framework for describing the technique of rsi is the "seven ps". preparation the patient is assessed to predict the difficulty of intubation. continuous physiological monitoring such as ecg and pulse oximetry is put on the patient. the equipment and drugs for the intubation are planned, including the endotracheal tube size, the laryngoscope size, and drug dosage. drugs are prepared in syringes. intravenous access is obtained to deliver the drugs, usually by placing one or two iv cannulae. preoxygenation the aim of preoxygenation is to replace the nitrogen that forms the majority of the functional residual capacity with oxygen. this provides an oxygen reservoir in the lungs that will delay the depletion of oxygen in the absence of ventilation (after paralysis). for a healthy adult, this can lead to maintaining a blood oxygen saturation of at least 90% for up to 8 minutes. this time will be significantly reduced in obese patients, ill patients and children. preoxygenation is usually performed by giving 100% oxygen via a tightly fitting face mask. preoxygenation or a maximum of eight deep breaths over 60 seconds resulting in blood oxygenation is not different from that of quiet breathing volume for 3 minutes. newer methods of preoxygenation include the use of a nasal cannula placed on the patient at 15 lpm at least 5 minutes prior to the administration of the sedation and paralytic drugs. high flow nasal oxygen has been shown to flush the nasopharynx with oxygen, and then when patients inspire they inhale a higher percentage of inspired oxygen. small changes in fio2 create dramatic changes in the availability of oxygen at the alveolus, and these increases result in marked expansion of the oxygen reservoir in the lungs prior to the induction of apnea. after apnea created by rsi the same high flow nasal cannula will help maintain oxygen saturation during efforts securing the tube (oral intubation). the use of nasal oxygen during pre-oxygenation and continued during apnea can prevent hypoxia before and during intubation, even in extreme clinical cases. pretreatment pretreatment consists of the medications given to specific groups of high-risk patients 3 minutes before the paralysis stage with the aim of protecting the patient from the adverse effects of introducing the laryngoscope and endotracheal tube. intubation causes increased sympathetic activity, an increase in intracranial pressure and bronchospasm. patients with reactive airway disease, increased intracranial pressure, or cardiovascular disease may benefit from pretreatment. two common medications used in the pretreatment of rsi include lidocaine and atropine. lidocaine has the ability to suppress the cough reflex which in turn may mitigate increased intracranial pressure. for this reason lidocaine is commonly used as a pretreatment for trauma patients who are suspected of already having an increase in intracranial pressure. although there is not yet definitive evidence to support this, if proper dosing is used it is safe. the typical dose is 1.5 mg/kg iv given three minutes prior to intubation. atropine may also be used as a premedication agent in pediatrics to prevent bradycardia caused by hypoxia, laryngoscopy, and succinylcholine. atropine is a parasympathetic blocker. the common premedication dose for atropine is 0.01–0.02 mg/kg. paralysis with induction with standard intravenous induction of general anesthesia, the patient typically receives an opioid, and then a hypnotic medication. generally the patient will be manually ventilated for a short period of time before a neuromuscular blocking agent is administered and the patient is intubated. during rapid sequence induction, the person still receives an iv opioid. however, the difference lies in the fact that the induction drug and neuromuscular blocking agent are administered in rapid succession with no time allowed for manual ventilation. commonly used hypnotics include thiopental, propofol and etomidate. the neuromuscular blocking agents paralyze all of the skeletal muscles, most notably and importantly in the oropharynx, larynx, and diaphragm. opioids such as fentanyl may be given to attenuate the responses to the intubation process (accelerated heart rate and increased intracranial pressure). this is supposed to have advantages in patients with ischemic heart disease and those with brain injury (e.g. after traumatic brain injury or stroke). lidocaine is also theorized to blunt a rise in intracranial pressure during laryngoscopy, although this remains controversial and its use varies greatly. atropine may be used to prevent a reflex bradycardia from vagal stimulation during laryngoscopy, especially in young children and infants. despite their common use, such adjunctive medications have not been demonstrated to improve outcomes. positioning positioning involves bringing the axes of the mouth, pharynx, and larynx into alignment, leading to what's called the "sniffing" position. the sniffing position can be achieved by placing a rolled towel underneath the head and neck, effectively extending the head and flexing the neck. you are at proper alignment when the ear is inline with the sternum. as described by brian arthur sellick in 1961, cricoid pressure (alternatively known as sellick's maneuver) may be used to occlude the esophagus with the goal of preventing aspiration. placement of tube during this stage, laryngoscopy is performed to visualize the glottis. modern practice involves the passing of a ‘bougie’, a thin tube, past the vocal cords and over which the endotracheal tube is then passed. the bougie is then removed and an inbuilt cuff at the end of the tube is inflated, (via a thin secondary tube and a syringe), to hold it in place and prevent aspiration of stomach contents. the position of the tube in the trachea can be confirmed in a number of ways, including observing increasing end tidal carbon dioxide, auscultation of both lungs and stomach, chest movement, and misting of the tube. postintubation management mispositioning of the endotracheal tube (in a bronchus, above the glottis, or in the esophagus) should be excluded by confirmation of end tidal co2, auscultation, fogging of the endotracheal tube, and observation of bilateral chest rise. history first described by william stept and peter safar in 1970, "classical" or "traditional" rsi involves pre-filling the patient's lungs with a high concentration of oxygen gas; applying cricoid pressure to occlude the esophagus; administering pre-determined doses of rapid-onset sedative and neuromuscular-blocking drugs (traditionally thiopentone and succinylcholine) that induce prompt unconsciousness and paralysis; avoiding any artificial positive-pressure ventilation by mask after the patient stops breathing (to minimize insufflation of air into the stomach, which might otherwise provoke regurgitation); inserting a cuffed endotracheal tube with minimal delay; and then releasing the cricoid pressure after the cuff is inflated, with ventilation being started through the tube. there is no consensus around the precise definition of the term "modified rsi", but it is used to refer to various modifications that deviate from the classic sequence – usually to improve the patient's physiological stability during the procedure, at the expense of theoretically increasing the risk of regurgitation. examples of such modifications include using various alternative drugs, omitting the cricoid pressure, or applying ventilation before the tube has been secured. special populations age can play a role in whether or not the procedure is warranted, and is commonly needed in younger persons. the clinician that performs rsi must be skilled in tracheal intubation and also in bag valve mask ventilation. alternative airway management devices must be immediately available, in the event the trachea cannot be intubated using conventional techniques. such devices include the combitube and the laryngeal mask airway. invasive techniques such as cricothyrotomy must also be available in the event of inability to intubate the trachea by conventional techniques. rsi is mainly used to intubate patients at high risk of aspiration, mostly due to a full stomach as commonly seen in a trauma setting. bag ventilation causes distention of stomach which can induce vomiting, so this phase must be quick. the patient is given a sedative and paralytic agent, usually midazolam / succinylcholine / propofol and intubation is quickly attempted with minimal or no manual ventilation. the patient is assessed for predictable intubation difficulties. laryngoscope blades and endotracheal tubes smaller than would be used in a non-emergency setting are selected. if the patient on initial assessment is found to have a difficult airway, rsi is contraindicated since a failed rsi attempt will leave no option but to ventilate the patient on bag and mask which can lead to vomiting. for these challenging cases, awake fiberoptic intubation is usually preferred. controversy since the introduction of rsi, there has been controversy regarding virtually every aspect of this technique, including: choice of intravenous hypnotic agents as well as their dosage and timing of administration dosage and timing of administration of neuromuscular blocking agents avoidance of manual ventilation before tracheal intubation optimal position and whether the head-up, head-down, or horizontal supine position is the safest for induction of anesthesia in full-stomach patients application of cricoid pressure, which is also referred to as the sellick maneuver.