Dietitian Blog, MNT Guidelines, Nutrition Support | Aug 11 2021
Your quick reference guide to assessing a ventilator patient
If you are working in an ICU or a long-term acute care (LTAC) facility, you are likely assessing patients who are receiving mechanical ventilation. This can be tricky because the patient can’t tell you any information or history. Cue the Dietitian Detective. Here’s how to find all the essential details.
Take it all in
Walking into a critically ill patient’s room can be overwhelming. There are machines, tubes, and alarms, oh my! Look first at the patient. Is he/she intubated with an endotracheal (ET) tube or is there a tracheostomy in place, both of which would be connected to the ventilator?
Is there an NG or OG tube? If so, note it. If not, note that too. If there is a Dobhoff tube present, find out where the tip is — in the stomach or the small bowel — since this will guide your tube feeding regimen.
Do a brief physical exam
Since most ventilator patients will be receiving some sort of nutrition support, make sure you feel the abdomen. Is it soft, distended, firm? Is there any edema present? Look specifically at the upper and lower extremities for edema. You can also note any obvious muscle wasting or fat loss around the face, clavicles, or shoulders. Don’t try to sit patients up or roll them over to complete the full nutrition-focused physical exam.
Check the floor
Seems strange to look here, right? On the floor (or hanging from the bottom of the bed), you will find chest tube receptacles, wound VACs, units designed to warm or cool the patient, Foley catheter bags, and rectal tube bags. All important things for you to be aware of.
Check the drips
Turn your attention to the IV poles. Here, you are looking specifically for three things: 1) IV fluids, 2) sedation agents, and 3) vasopressors. It’s important to check these medications “in real time” because the sedation and vasopressor drugs are titrated and often change throughout the course of the day, despite what is listed in the EMR. Another approach is average the doses over the past 24 hours. You’ll find this information in the EMR.
There are some clues in the types of sedation drugs that can help you figure out if the patient may be extubated soon. Drugs like propofol (Diprivan®) and dexmedetomidine HCl (Precedex®) are shorter acting, which means the patient can wake up and be alert much quicker after the infusion is turned off.
On the other hand, midazolam (Versed®) and fentanyl (Sublimaze®) are longer lasting and may take hours to wear off after infusion has stopped. Patients receiving the latter two medications are less likely to be extubated in the immediate future, given the long-lasting effects of the sedation.
Read the ventilator settings
There are more clues on the ventilator itself. First, what ventilator mode is the patient receiving? Assist control (AC) provides a set number of breaths per minute, the same volume of air for each breath, and is one of the highest levels of respiratory support.
Synchronized intermittent mandatory ventilation (SIMV) is similar to AC, in that there are a set number of breaths per minute. Breaths delivered by the vent will be of a standard volume of air, but SIMV allows patient-initiated breaths to be whatever volume of air the patient chooses. This increases the patient’s work of breathing and independence.
Pressure Support (PS) is a weaning mode. Patients must initiate all their own breaths and the vent provides support in helping the patient inhale a sufficient volume of air. As the patient moves toward extubation, the pressure decreases to a number near 8.
Other than the vent mode, look also at the PEEP and FiO2. PEEP is the amount of pressure applied at the end of a breath to keep alveoli open. FiO2 is the percentage of oxygen needed to maintain blood oxygen levels. A high PEEP (over 5) and high FiO2 (100% is the highest) usually means the patient is still receiving significant ventilator support. Find out more about ventilator settings.
Check the monitor
Look up to find the vital signs monitor. Here, you are looking for the mean arterial pressure (MAP). Generally, the MAP can be found on the monitor in parentheses after the blood pressure.
Something like this: 148/75 (99). In this scenario, the MAP is 99. For a dietitian’s purposes, the MAP lets you know whether the patient is hypotensive to the point that it would be unsafe to feed enterally. Use extreme caution with enteral nutrition when the MAP is below 65.
Don’t be afraid to ask questions while you are learning. Talk to the nurse, the respiratory therapist, the pharmacist, and the physician. Pretty soon, you’ll be a pro!
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Reference:
Miller N. Set the stage for ventilator settings. Nursing made incredibly easy! 2013;11(3):44-52. doi: 10.1097/01.NME.0000428429.60123.f
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