Methods to Improve Ventilation in PT ventilator Management

Question 1

-Ventilation and PaCO2

-When PaCO2 is increased above the Pts normal value and PH decreases, respiratory acidosis is present (Hypoventilation) ex ph -7.25, PaCo2 -80 mmHg

Answer 1

-The Pts alveolar ventilation is not adequate

		-Alveolar ventilation is effect ventilation

	-When the vent is volume controlled, increasing the tidal volume up to 10 ml/kg, will decrease the PaCO2

	-If the tidal volume is already at 10 ml/kg then the rate can be increased

	-If the vent is pressure cycled, the cycling pressure is increased (PIP)

Question 2

when you wish to normalize a high PaCO2, you should:

Answer 2

1.Remove mechanical dead space

2.Increase Vt or PIP (Do IBW VT range)

3.Increase the RR (especially if VT is already in range)

Question 3

-Ventilation and PaCO2

-When PaCO2 is decreased below the PTs normal value and PH reflects a respiratory alkalosis, then excessive alveolar ventilation is present (Hyperventilation).. Ex 7.54, Paco2 22

Answer 3

-To decrease ventilation in volume controlled ventilator, decrease the respiratory rate

-Then if necessary, decrease the tidal volume but preferably Not below 6ml/kg

-If the vent is pressure cycled, decrease the rate first and then the cycling pressure (PIP) if needed

-Assist control is not a good mode for respiratory alkalosis

Question 4

when you wish to normalize a low PaCO2, you should:

Answer 4

Evaluate the cause (Hypoxemia, pain, fever, anxiety)

Decrease the RR

Decrease the Vt or PIP

Question 5

-If the PT is in respiratory alkalosis ventilation, decreasing the machine rate setting may have no effect in the PTs rate if the PT is initiating all breaths

so,

Answer 5

-Decreasing the tidal volume may be effective unless the PT just increases his or her RR and thus maintains a high alveolar ventilation

-In the situation, 3 alternative are available

	-Institute SIMV to allow the PT to breath without getting a machine breath with every inspiration

	-Sedate and if necessary, paralyze the PT to completely control breathing. This may be needed for PT with seizures or with tetanus, but otherwise is not the best choice

	-Add mechanical Dead Space (Vdmech)

Question 6

Correcting PaCO2 Abnormalities
-If its desirable to keep the PTs rate constant and change the tidal volume, use this equation:

Answer 6

-Desired Vt= Known PacO2 * Known Vt/ Desired PaCO2

-Example: Known PaCO2 = 60 mmHg,known Vt =350 ML, Desired PaCo2 40 mmHg

	-60*350/40=525

Question 7

Correcting PaCO2 Abnormalities

-If it is appropriate to keep the VT the same and change the rate, then use this equation:

Answer 7

-Desired F= known PaCO2 * Known F/ Desired PaCO2

-Example: Know PaCo2= 60 mmHg, Known F= 10, desired PaCO2= 40 mmHg

	-60*10/40= 15

Question 8

Correcting PaCO2 Abnormalities

-Example 1

	-The PT is a 6’2 male and weighs 190lbs. The exhaled Vt measured at the ET tube is 500ml. RR is 10 bpm. The pt is on controlled ventilation. PaCO2 is 50 mmHg, ph is 7.33. The Pts desired PaCO2 is 40 mmHg. What vent change must be made to decrease the Pts PaCO2.

Answer 8

-1st Build Vt range which is 465-625

	-Answer both equations to see which is the best solution

		Desired Vt = 624

		Desired F= 12.5

			-Vt is in range but adjust rate because its set at 10

Question 9

Example 2

-A 5’2 woman on Controlled ventilation has a PaCO2 of 58 mmHg, ph is 7.28. Vt at ET tube is 375 ml. RR is 7 bpm. How can a desired PaCO2 of 40 mmHg be achieved

Answer 9

-Build Vt range 300-400

		Desired Vt 543.75

		Desired RR 10.15	

			-Both answers are wrong but Vt is already in range adjust RR

Question 10

Example 3

-A 5’10 Male pt is in respiratory alkalosis with the following values: PaCO2= 25 mmHg, and PH = 7.60 in control mode with a delivered Vt of 575, F 16 bpm. The desired PaCO2 is 40 mmHG

Answer 10

-Vt Range 438-584

-Desired Vt 359

-Desired RR 10

-Decrease RR