can be inflated. some benefits of the laryngeal mask airway include minimization of gastric inflation and protection against regurgitation. a potential problem the laryngeal mask airway poses is that over inflation will make the mask more rigid and less able to adapt to the patient's anatomy, compressing the tongue and causing tongue edema. in that case, the mask pressure should be lowered or a larger mask size should be used. if non-comatose patients are given muscle relaxants before the insertion of the laryngeal mask airway, they may gag and aspirate when the drugs are worn off. at that point, the laryngeal mask airway should be removed immediately to eliminate the gag response and buy time to start at new alternative intubation technique. endotracheal intubation a tracheal tube is inserted into the trachea through the mouth or nose. endotracheal tubes contain high-volume, low-pressure balloon cuffs to minimize air leakage and the risk of aspiration. cuffed tubes were made originally for adults and children over 8 years old, but cuffed tubes have been used in infants and younger children to prevent air leakage. cuffed tubes can be inflated to the extent needed to prevent air leakage. the endotracheal tube is a guaranteed mechanism to secure a compromised airway, limit aspiration, and bring about mechanical ventilation in comatose patients. the endotracheal tube is a great method for patients who are comatose, have an obstructed airway, or need mechanical ventilation. the endotracheal tube also allows suctioning of the lower respiratory tract. drugs that can be inserted through the endotracheal tube during cardiac arrest are discouraged. before intubation, patients need correct patient positioning and ventilation with 100% oxygen. the purpose of ventilation with 100% oxygen is to denitrogenate healthy patients and prolong the safe apneic time. tubes with an internal diameter of over 8mm are acceptable for most adults. insertion technique includes visualizing the epiglottis, the posterior laryngeal structure, and not passing the tube unless tracheal insertion is ensured. surgical airway surgical entry is required when the upper airway is obstructed by a foreign body, massive trauma has occurred, or if ventilation cannot be accomplished by any of the aforementioned methods. the requirement of the surgical airway is commonly known as the response to failed intubation. in comparison, surgical airways require 100 seconds to complete from incision to ventilation compared to laryngeal mask airways and other devices. during emergency cricothyrotomy, the patient lies on his back with neck extended and shoulders backward. the larynx is held in one hand by the practitioner while the other hand is holding a blade to incise the skin through the subcutaneous tissue and into the midline of the cricothyroid membrane to access the trachea. a hollow tube is used inserted into the trachea to keep the airway open. a tracheal hook is used to keep the space open and prevent retraction. complications may include hemorrhage, subcutaneous emphysema, pneumomediastinum, and pneumothorax. cricothyrotomy is used as emergency surgical access due to being fast and simple. another surgical airway method is called tracheostomy. tracheostomy is done in the operating room by a surgeon. this is the preferred method for patients requiring long-term ventilation. tracheostomy uses skin puncture and dilators to insert the tracheostomy tube. drugs to aid intubation patients with respiratory arrest can be intubated without drugs. however, patients can be given sedating and paralytic drugs to minimize discomfort and help out with intubation. pretreatment includes 100% oxygen, lidocaine, and atropine. 100% oxygen should be administered for 3 to 5 minutes. the time depends on pulse rate, pulmonary function, rbc count, and other metabolic factors. lidocaine can be given in 1.5 mg/kg iv a few minutes before sedation and paralysis. the purpose of administering lidocaine is to blunt the sympathetic response of an increased heart rate, blood pressure, and intracranial pressure caused by laryngoscopy. atropine can be given when children produce a vagal response, evidenced by bradycardia, in response to intubation. some physicians even give out vecuronium, which is a neuromuscular blocker to prevent muscle fasciculations in patients over 4 years old. fasciculations may result in muscle pain on awakening. laryngoscopy and intubation are uncomfortable procedures, so etomidate may be delivered. etomidate is a short-acting iv drug with sedative analgesic properties. the drug works well and does not cause cardiovascular depression. ketamine is an anesthetic that may be used as well, but it may cause hallucinations or bizarre behavior upon awakening. thiopental and methohexital may be used as well to provide sedation, but they tend to cause hypotension. volume-cycled ventilation the purpose of mechanical ventilators is to deliver a constant volume, constant pressure, or a combination of both with each breath. any given volume will correspond to a specific pressure on the pressure-volume curve and vice versa in any case. settings on each mechanical ventilator may include respiratory rate, tidal volume, trigger sensitivity, flow rate, waveform, and inspiratory/expiratory ratio. the volume-cycled ventilation includes the volume-control function and delivers a set tidal volume. the pressure is not a fixed number but it varies with resistance and capacitance of the respiratory system. the volume-cycled ventilation is the simplest and most efficient of providing ventilation to a patient's airway compared to other methods of mechanical ventilation. each inspiratory effort that is beyond the set sensitivity threshold will be accounted for and fixed to the delivery of the corresponding tidal volume. if the patient does not breathe enough, then the volume-cycled ventilation will initiate a breath for the patient to bring up the breathing rate to the minimum respiratory rate. the synchronized intermittent mandatory ventilation (simv) is a similar method of mechanical ventilation that also delivers breaths at a fixed rate and volume that corresponds to the patient's breathing. unlike the volume-cycled ventilation, patient efforts above the fixed rate are unassisted in the synchronized intermittent mandatory ventilation (simv). pressure-cycled ventilation the pressure-cycled ventilation includes pressure control ventilation and pressure support ventilation. both methods offer a set inspiratory pressure. the tidal volume varies depending on the resistance and elastance of the respiratory system. pressure-cycled ventilation can help alleviate symptoms in patients with acute respiratory distress syndrome by limiting the distending pressure of the lungs. the pressure control ventilation is specifically a pressure-cycled form of assist-control ventilators. assist-control ventilators describe a mode of ventilation that maintains a minimum respiratory rate regardless of whether or not the patient initiates a spontaneous breath. each inspiratory effort that is beyond the sensitivity threshold delivers full pressures support for a fixed inspiratory time. there is maintenance of a minimum respiratory rate. in the pressure support ventilation, the minimum rate is not set. instead, all breaths are triggered by the patient. the way that the pressure support ventilation works is by assisting the patient with a constant pressure until the patient's inspiratory flow falls below a threshold. the longer, deeper inspiratory flows by the patient will result in a larger tidal volume. this method of mechanical ventilation will help patients assume more work of breathing. noninvasive positive pressure ventilation (nippv) noninvasive positive pressure ventilation is the delivery of positive pressure ventilation through a tight-fitting mask that covers the nose and mouth. it assists patients who can spontaneously breathe. noninvasive positive pressure ventilation delivers end-expiratory pressure with a volume control setting. there are two ways that noninvasive positive pressure ventilation can be delivered: continuous positive airway pressure or bilevel positive airway pressure. in continuous positive airway pressure, constant pressure is maintained throughout cycles of respiration with no additional inspiratory support. in bilevel positive airway pressure, both expiratory positive airway pressure and inspiratory positive airway pressure are set by the physician. noninvasive positive pressure ventilation should not be administered to people who are hemodynamically unstable, gastric emptying impaired, bowel obstructed or pregnant. in these circumstances, swallowing large amounts of air will result in vomiting and possibly death. if frequent arrhythmias, myocardial ischemia and shock arrhythmias occur, practitioners should change delivery to endotracheal intubation or conventional mechanical ventilation. people who should not use noninvasive positive pressure ventilation include obtunded patients or ones with secretions. noninvasive positive pressure ventilation can be used in an outpatient setting for patients with obstructive sleep apnea.