prior to apnea testing all of the details clinically and by neuroimaging should point to the fact that the patient that you are going to perform the apnea test on has progressed to brain death the environmental preparation and patient preparation requires that several prerequisites are accomplished first the patient should be euthermic in addition patient should be normotensive this may require a combination of vasopressors and fluid resuscitation prior to apnea testing patients should be hyper oxygenated on 100% oxygen and the respiratory rate should be decreased in order to achieve a normal pco2 breaths per minute at least 10 minutes after these changes are made a baseline arterial blood gas should be sent that Baseline blood gas will ideally demonstrate normalization of the carbon dioxide to at least 40 mm of mercury and high oxygen levels of greater than 200 mm of mercury prior to commencement with the apnea test an insulation catheter should be prepared in order to deliver 100% oxygen at a rate of between 4 to 6 lers per minute from the wall oxygen the oxygen should not be delivered at a higher flow rate than this since that higher flow rate may wash out carbon dioxide from the LV and prevent the requisite rise of carbon dioxide the anticipated rise of carbon dioxide will be somewhere between 2 to 4 millim of mercury per minute in the euthermic apnic patient so one should anticipate that the apnea test will take at least 5 to 10 minutes in order to achieve the requisite CO2 rise to greater than 60 mm of mercury by convention and by guidelines it's recommended that an apnea test is performed at least for 8 minutes and longer if the patient remains hemodynamically stable without hypoxemia when the physician is ready to perform the apnea testing the mechanical ventilator should be discontinued by disconnecting the ventilator tubing to the patient's endot tral tube often turning the machine off afterwards is helpful in order to prevent continuous alarming of the ventilator turn on the wall oxygen to a flow rate between 4 to 6 L per minute then connect the taped suction catheter to the wall oxygen insert the tape section catheter into the endot tral tube to provide apnic oxygenation during the apnea test Bas oppressors should be available at the bedside to administer to the patient in case hypotension or relative blood pressure lowering is occurring as CO2 climbs and respiratory acidosis ensues the chest should be bared in order to observe for any spontaneous respirations an apent test must be aborted if there is either spontaneous respirations observed or hypoxemia with an oxygen saturation less than 85% for longer than 30 seconds or intractable hypotension with systolic blood pressures consistently less than 90 m mm of mercury not readily responsive to vasopressors in the case where hypoxemia has not occurred and the blood pressure can be maintained the apnea test duration should be at least 8 minutes and longer in patients that are hemodynamically stable as the apnea testing is coming to completion a final blood CK should be sent prior to reconnecting the mechanical ventilator when the mechanical ventilator is reconnected the respitory rate should be turned up to somewhere between 16 to 20 breaths per minute in order to hyperventilate the patient and blow off the carbon dioxide in order to avoid post apnea test hypotension from respiratory acidosis when a patient has had a positive apnea test and the requisite CO2 rise has been demonstrated without any respirations a patient's death can then be pronounced with the timing of death being when it has been documented for