Mr. Hill has been on the ventilator for 24 hours. You volunteered to care for him today, since you know him from the intubation yesterday. The settings ordered by the pulmonologist after intubation were as follows: A/C, rate 14, V_T 700, FIO₂ 60%. Since 0700, Mr. Hill has been assisting the ventilator with a respiratory rate of 24 (It’s now 1100).

1. Describe the ventilator settings.

Answer:

The ventilator delivers 14 breaths per minute, each with a tidal volume of 700 ml. The A/C mode delivers the breaths in response to Mr. Hill’s own respiratory effort, but will initiate the breath if he doesn’t within the set amount of time. (He’s currently breathing above the vent setting.) The oxygen concentration is 60%.

You notice that Mr. Hill’s pulse oximetry has been consistently documented as 100% since intubation. You also notice that his respiratory rate is quite high and that he’s fidgety, doesn’t follow commands, and doesn’t maintain eye contact when you talk to him. He hasn’t had any sedation since he was intubated.

2. Which lab test should you check to find out what his true ventilatory status is?

Answer:

Arterial blood gas (ABG) - which he should have had done with his morning labs. If not, check with the pulmonologist about getting one.

3. Which two parameters on the ABG will give you a quick overview of Mr. Hill’s status?

Answer:

PaCO₂ (which affects the pH) and PaO₂. With his high respiratory rate, Mr. Hill is at risk for hypocapnia from “blowing off CO₂.”  If the PaO₂ is adequate, the FIO₂ could be decreased, since his oxygen saturation has been consistently 100%.

4.  What are some possible causes of Mr. Hill’s increased respiratory rate? (Give the corresponding nursing interventions as well.)

Answer:

Secretions - suction through the ETT, as well as his mouth.

Anxiety or pain - Mr. Hill hasn’t received any sedation since he was intubated. At this point, he should at least have a prn order for sedation, if not a continuous IV infusion.

The vent settings may not be appropriate – check the ABG’s and notify the pulmonologist.

Mr. Hill didn’t have an ABG done this morning, so you get an order from the pulmonologist to get one now (1130). When it comes back, the PaCO₂ is 28, the pH is 7.48, and the PaO₂ is 120 (normals: PaCO₂ 35-45 mm Hg, pH 7.35-7.45 mm Hg, PaO₂ 80-100 mm Hg).

5. Based on the ABG, the pulmonologist changes the vent settings to SIMV, rate 10, PS 10, FIO₂ 40%. The V_T remains 700. How will these new settings help Mr. Hill?

Answer:

SIMV will deliver 10 breaths with the full tidal volume each minute, but in synchrony with Mr. Hill’s spontaneous breaths. This mode is not triggered to deliver a breath each time Mr. Hill inhales, and the tidal volume of his spontaneous breaths is under his control. Pressure support decreases the work of breathing that results from breathing through the ventilator circuits and tubing. The PaO₂ was higher than desired, indicating that the FIO₂ could be decreased. We need to be careful to prevent oxygen toxicity.

The pulmonologist also orders midazolam (Versed) 1-2 mg every hour prn for sedation.