part0021

Your mother was right—nothing good happens after 2 A.M. Especially in the ICU. If you get called to the bedside of a critically ill patient in the middle of the night, it is almost never going to be for good news.

This chapter is designed as a step-by-step approach to the mechanically ventilated patient who is either not getting better or deteriorating despite your best efforts. It begins with the things you should check when a patient has a sudden change in condition. Some of this is also discussed in The Ventilator Book , but it doesn't hurt to read it again. There is also a stepwise algorithm for escalating ventilator support for severe ARDS, as well as a guide to initial vent settings for acute lung injury and obstructive lung disease. Despite the title of this chapter, this information is useful any time of day.

Whenever a critically ill patient takes a turn for the worse, the initial assessment should go back to the ABCs. This is drilled repeatedly in Advanced Cardiac Life Support and Advanced Trauma Life Support courses, and for good reason. For a mechanically ventilated patient, think Tube, Sounds , Sats . Make sure the endotracheal tube is in place and is patent—capnography is very helpful in this regard. Auscultate the chest to make sure there is bilateral air entry, and listen for wheezing or rales that might point you toward the reason for the patient's deterioration. Ensure that the patient is adequately oxygenated—hypoxemia can be due to a mechanical problem, a pulmonary issue, a cardiovascular issue, or a combination of any of these.

• D isplacement of the endotracheal tube—assess with capnography to make sure the tube is still in the trachea. Mainstem intubation can also make a ventilated patient get worse. The tube usually migrates down the right mainstem bronchus, so if breath sounds are not equal pull the tube back a few centimeters and reassess.

• O bstruction of the endotracheal tube—again, capnography can be helpful. A suction catheter that doesn't easily pass is another clue. Make sure the tube isn't kinked. Tube obstructions from secretions can sometimes be cleared with a bronchoscope or a CAM Rescue Cath™. If there's any doubt, take a look with a laryngoscope and reintubate the patient with a fresh tube.

• P neumothorax—chest X-ray is usually helpful but may not be immediately available. Bedside ultrasound can show a lack of pleural sliding. If there's concern for a tension pneumothorax (hypotension, hypoxemia, and absent breath sounds), emergent decompression should be strongly considered.

• E quipment malfunction—the best way to exclude this as a cause is to disconnect the patient from the ventilator, attach a self-inflating bag, and manually ventilate while further assessments are performed .

• S tacked breaths—this almost always happens in severe obstructive lung disease. Auto-PEEP can progress to the point where it causes hypotension or even pulselessness. A clue is when the patient is very difficult to manually ventilate and breath sounds are markedly diminished bilaterally. The treatment is disconnection of the vent or bag—if there's a rush of air out of the endotracheal tube, followed by hemodynamic improvement, then auto-PEEP is the culprit. Reconnect the patient to the ventilator with a lower respiratory rate and ensure that there's enough time for exhalation.

These are general guidelines for initial ventilator settings, divided between acute lung injury (sepsis, trauma, ARDS, pulmonary edema, etc.) and obstructive lung disease (asthma, COPD). The specific ventilator management of these patients must be individualized, and the general principles are described in more detail elsewhere. The purpose of these guidelines is to provide a quick reference that is applicable to the majority of patients placed on the ventilator in the ICU or the Emergency Department.