guidelines to adjusting ventilator settings

So you're tired of doctors just making up ventilator changes. Here are the recommended AARC guidelines for adjusting ventilator settings. Study these, and impress a doctor or a nurse with your wisdom:

1. PaCo2 greater than 45 (or EtCo2 greater than 50)

• Increase RR
• Increase VT

2. PaCo2 less than 35 (or EtCO2 less than 30)

• Decrease Rate
• Decrease VT

3. PO2 less than 60 (or SpO2 less than 90%)

• Increase FiO2 to 60%
• Increase PEEP
  
• Increase FiO2 to 100%

4. SpO2 greater than 95% (or appropriate oxygenation for patient)

• Reduce FiO2 to 60%
• Reduce PEEP to 5
  

This is to act as a guideline only to assist you in making the appropriate ventilator changes based on invasive ABG results and/ noninvasive EtCO2 and SpO2 monitoring. Of course you'll need to know your patient.

For a great review of EtCO2 monitoring check out this post.

For a printable cheat sheet with this information and more, click here.

For a printable cheat sheet for EtCO2 monitoring click here.

Ventilator Management Protocol

I am presently working on writing the ideal ventilator management protocol to go with our extubation protocol. Please help me out by adding any ideas or recommendations for the protocol below:

(For a printable copy, click here)

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1. Scope: A Licensed Registered Respiratory Therapist (RRT) who has successfully completed and passed all competencies related to patient assessment and protocols. Certified Respiratory Therapists, respiratory students and assistants may not adjust Mechanical ventilators per protocol.

2. Policy:

A. The Mechanical Ventilator Management Protocol will only be initiated on patients ordered on Vent Management Protocol (VMP), or if the attending physician orders RT Consult on a mechanically ventilated patient.

B. The attending physician may write “discontinue Vent Management Protocol”
(VMP) or discontinue RT Consult at any time.

C. The physician does not need to be notified if:

• a. Weaning FiO2
• b. Increasing FiO2 if not going greater than 50%
• c. Increase in PSV of 5 or less to maintain adequate tidal volume
• d. Changing in and out of volume support

D. The physician will be notified when:

• a. The respiratory therapist wishes to initiate VMP on a patient who is not Currently on the protocol
• b. If the patient’s condition is deteriorating.
• c. The respiratory therapist is unable to determine appropriate therapy.
• d. If the FiO2 is greater than 60% and PaO2 less than 60mmHg or SpO2 less than 90% with

5cmH20 PEEP.

e. When pre-determined therapy limits are reached, i.e. FiO2, Vt, PEEP, RR, etc.

f. When PEEP greater than 5 is indicated.

g. If PEEP greater than5 has been approved, and now PEEP less than 8 is indicated.

h. A RR greater than 30 or less than 8 is indicated

i. A VT greater than 10 ml/kg ideal body weight or less than 6 ml/kg is indicated.

j. If VT or PEEP is indicated that results in PIP greater than or = 40 or plateau pressure greater than 30.

k. Weaning success or failure

l. Increasing FiO2 above 50% is indicated to maintain sats

m. Change in PSV greater than 5 cmH20 is made

n. A change in tidal volume is made

o. A change in respiratory rate is made

E. For continuous monitoring of ABG values, an arterial line should be introduced, and/or the use of non-invasive monitoring (SpO2 & EtCO2)should be employed. Non-invasive monitoring is preferred.

F. Modify ventilator settings as indicated to maintain target values.

G. Assure the non-invasive oxygen saturation (SpO2) and end tidal CO2 (EtCO2) values correlate with current ABGs.

H. If rate of greater than 30 is indicated, consider sedation prior to calling physician.

I. Maximum PIP is determined by increasing PEEP in increments of
1cmH20. Stop increasing when BP, HR, SpO2 drop, or PaO2/Fio2 Ratio = or less than 200. If the PaO2/FiO2 ratio increases you know PEEP therapy is working.

J. When considering the adjustment of FiO2, hemoglobin should be checked to ensure the absence of anemia. Hemodynamic data should be checked to ensure adequate circulation.

3. Ventilator Management Protocol: The following are guidelines for use in stabilization and management of the patient on mechanical ventilation:

A. The following values will be maintained, unless otherwise ordered by physician.

• a. Ph: 7.35 to 7.45
• b. PaCO2: 35 to 45 mmHg (EtCO2: 30 to 50 mmHg), unless the patients “usual” PaCO2 is chronically elevated.
• c. PaO2: 60 to 100 mmHg (SpO2 greater than 90%)
• d. In patients with COPD, adjust parameters to the patient’s “normal” values

B. Obtain ABG or non-invasive oxygen saturation (SpO2) and end tidal CO2

C. Adjust the ventilator settings to correct abnormal ABG and/or SpO2 and EtCO2 values.

a. Abnormal PaCO2 greater than 45 mmHg (EtCO2) values:

• 1. Increase rate in increments of 2 to obtain acceptable values.
• 2. Increase Tidal Volume by increments of 50ml to obtain acceptable values

b. Abnormal PaCO2 less than 35 mmHg (EtCO2) values:

• 1. Decrease rate in increments of 2 to obtain acceptable values.
• 2. Decrease Tidal Volume by increments of 50ml to obtain acceptable values.

c. Abnormal PaO2/SpO2 values:

• 1. PaO2 less than 60 mmHg or SpO2 less than90%, increase FiO2 in increments of 05% to obtain acceptable values.
• 2. For hypoxia (Sa02 less than 92%)requiring greater than 60% FiO2, increase PEEP in steps of 1 cmH20 at a time to PEEP max (specific Dr. order required)
• 5. With PEEP = or greater than 5 & PaO2 greater than 100 mmHg or Spo2 greater than 95%, decrease FiO2 in increments of 05% to obtain acceptable values.
• 6. If the SpO2 or PaO2 is not adequate after any weaning attempt of the Fi02, increase the Fi02 to the previous setting. Continue weaning the Fi02 as tolerated by patient.

D. Non-invasive monitoring or ABG criteria is not the absolute control for maintaining Ventilatory support. Sudden changes in cardiovascular status, respiratory rate, and color may mandate a change in ventilator parameters.

E. Once patient is stabilized, and once the problem that resulted in the need for Ventilatory support has been resolved, the patient should be continuously monitored for indications for weaning (See Ventilator Weaning Protocol).

4. Documentation:

A. Initial assessment

• a. An RT assessment will be performed within 15-45 minutes from start of ventilation.
• b. Assessment will include evaluation of the patient’s general appearance, blood pressure, heart rate, breath sounds, ventilating pressures, volumes and ABGs.
• c. Assessments may also include additional data, when available, such as EtCO2 and hemodynamic data.
• d. Ventilator checks will be completed every two hours and documented accordingly. Checks will include ventilator settings, pressures, and essential alarms
• e. Cuff pressure will be checked once per shift, and a minimum cuff pressure of 20 cwp will be maintained in order to minimize VAP.
• f. All therapy will be documented in computer charting.

B. Re-assessments

• a. Regular assessment of general appearance, vital signs, breath sounds and Hemodynamic stability should be evaluated prior to and during any ventilator adjustment.
• B. Adjustments of the patient’s therapy will be determined objectively by changes in the monitored parameters.

5. References:

1. Mechanical Ventilator Protocol, Retrieved from: http://rtcorner.net/rt_forms.htm
and http://rtcorner.net/rt_forms.htm

2. Mechanical Ventilator Protocols, Retrieved from:
http://www.aarc.org/resources/protocol_resources/documents/general_vent.pdf
3. CTICU Weaning Protocol, retrieved from: http://www.dhmc.org/webpage.cfm?site_id=2&org_id=116&morg_id=0&sec_id=0&gsec_id=5560&item_id=7386

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For a related article, check out "Ventilator Weaning Protocols" by Bill Croft @ rtmagazine.com

How to ventilate morbidly obese patients

So you have a family practitioner doctor who does not have ventilator privileges standing over the bed of a morbidly obese patient who was just intubated and he says, "Gee, what tidal volume should we use. Let's see. How much does she weigh?"

By now you are already rolling your eyes and biting your cheek to prevent yourself from blurting our or, worse, actually slapping the doctor. Yet you're politically patient.

A nurse says, "I bet she's at least 500 pounds."

"Well then, " the good doctor says, "Let's set the tidal volume at 1,000." He looks at you.

While this is all going on you take your trusty ruler from your pocket and measure the length of the patient. You come up with 5 feet 6.5 inches. Based you your hospital's tidal volume protocol of 6-10cc/kg ideal body weight (not actual body weight), you come up with a tidal volume of between 420 and 700.

The doctor leaves the room, and you set up the vent and place the tidal volume at 500. You go low because the patient has a suspected lung problem. You can always adjust it higher later up or down if needed.

This happens very seldom anymore, but this is a scenario that I experienced in the past year. Thankfully we had a ventilator protocol, and the physician giving me the orders did not have ventilator privileges. Usually when this happens it's a family practice doctor or a surgeon. Surgeons are notorious for wanting those high tidal volumes.

And it's understandable, because back when I went through RT School the tidal volumes taught to us were on the high range. We were taught 10-15 cc/kg ideal body weight. And that tidal volume is fine for a completely healthy person. But you have to consider that most people ventilated in the ER and CCU do not have normal lungs, and you are better off ventilating on the low end, and adjusting later.

That said, obese patients do not have larger lungs. If you have a 100 pound lady who is 5 feet 8 inches tall her lungs are basically the same size as a lady who is 200 pounds at 5 feet 8 inches, and the same size as a lady who is 500 pounds at 5 feet 8 inches.

So if you ventilate either of these ladies based on their weight, you may be under ventilating or over ventilating. However, it's safer to under ventilate than over ventilate. If you over ventilate that 500 pound lady you might end up blowing up her lungs. Thus, it is highly possible you just saved this family practice doctor from a major law suit and he didn't even know about it.

You can read a great article about this here at PulmonaryReviews.com. According to this article there are other things we can do to help these patients better ventilate:

Putting the head of bed up 30 degrees so their abdomen is not pressing up against the diaphragm and impeding breathing. Where I work this is part of the ventilator protocol for all patients to diminish the chance of ventilator acquired pneumonia. Likewise, obese patients may become hypoxic in a supine position.

PEEP may also help with hypoxia. According to the above mentioned article, " In a study of nine obese patients who were anesthetized and supine after abdominal surgery, 10 cm H2O of PEEP was shown to markedly improve lung volumes and pulmonary compliance.[2] Those improvements were minimal in a comparison group of normal-weight patients.

For those with poor vasculature, ultrasonography may be very helpful in helping nurses find a vein, and a doppler may also be helpful. A doppler might also be tried if an ABG draw is needed.

Before these patients are intubated the patient should be trialed on BiPAP. I must admit that BiPAP is a machine that is used much more than it was when I started as an RT 10 years ago, and I have seen remarkable results. In many cases the BiPAP may prevent the patient from needing to be intubated.

According to this article you were just in going with the lower tidal volume, as their recommendation is to ventilate at tidal volumes of 5-7 cc/kg ideal body weight.

When it comes to medication, the article notes that "excessive weight-based dosages may be reasonable for medication-related adverse events in morbidly obese patients." Thus, when administering opoids, it is recommended that this be administered in "frequent small doses... until the desired level of pain control is achieved."

When weaning these patients it's best to have them sitting up in a 90 degree angle, or having them in a "reverse trendelenberg" position with their feet on the ground. With some of our newer beds this is possible. Studies, however, show the 45 degree angle worked best for weaning.