How To Normalize High Co2 Levels

How To Correct Patients With High Co2 Levels 

To normalize a HIGH PaCO2 you should:

1. Decrease or remove deadspace

2. Increase Tidal Volume

3. Increase Respiratory Rate

To normalize a LOW PaCO2 you should:

1. Increase Deadspace

2. Decrease the Respiratory Rate

3. Decrease the Tidal Volume

To increase a LOW PaO2

1. FIRST - increase Fio2 by 5-10% (up to 60%)

2. THEN - Increase PEEP lvls by 5cmH20 until:

- acceptable oxygenation is achieved

- unacceptable side-effects occur (decrease in complaince, decrease in cardiac function, barotrauma)

To decrease a HIGH PaO2

1. FIRST- decrease FIO2 to less than .60

2. THEN - decrease PEEP

I:E Ratio (flow rate)

1. I:E Ratio is the amount of time for inspiration compared to the amount of time for exhalation

2. Expiratory time should normally be greater than inspiratory time (1:2, 1:3)

3. COPD pts need more time to exhale (I:E ratio- 1:4, 1:5)

4. Increasing the flow rate will increase the time of exhalation

Adjust Expiratory Retard (Expiratory Resistance)

Similar to purse-lip breathing, slows exhalation

1. Decreases the FRC

2. Used with COPD pts to prevent airway collaspe

3. Does not change I:E ratio or lengthen expiratory time

4. It is recommended to increase expiratory time by increasing flowrate or decreasing respiratory rate, to allow for complete exhalation to occur (prevent air trapping)

Adjusting Inspiratory Plateau (Inflation Hold)

1. Patient is forced to hold tidal volume at the end of the breath for a short time (0to2 sec)

2. Extends the total inspiratory time, decreases the time foor exhalation, and increases mean airway pressure

3. To maintain the same I:E ratio would require an increase in the flow rate to shorten inspiratory time

4. NOT to be used with closed head injurys

5. Contraindicated in hypotensive pts

Positioning the patient for mechinical ventilation

1. The patient shoould be placed in a supine position initially

2. Low to Semi fowlers may be used later. Best position for optimal mechinical ventilation

Adjusting Pressure Support

1. Pressure Support is a mode available on some ventilators which provides a present amount of pressure during a spontaneous breath in SIMV

2. This helps the patient overcome the resistance of breathing through the vent circuit

3. Pressure support can then be adjusted above the resistance of the ventilator circuitry to assist the patient if their tidal volume is not sufficient

4. Pressure Support values are measured above the baseline pressures

5. Used with patients who have difficulty weaning


1. Used to increase pts FRC

2. Improves (Increases) compliance

3. Improves oxygenation (Pa02) problems by shunting. Improves myocardial oxygenation and increases cardiac output

4. PEEP/CPAP 10-30 or more= Therapy

5. PEEP/CPAP 2-10 = Physiological

6. Increase or decrease PEEP/CPAP by 2-5 cmH2

PEEP/CPAP is improving pts status when:

1. PO2 increases

2. Static Compliance increases (corrected plateau pressures decrease)

3. Cardiac output and hemodynamic pressures are stable (PAP, PWP)

CPAP/PEEP is too high when

1. PO2 decreases

2. Static Compliance decreases

3. Cardiac Output decreases and hemodynamic pressures increases (PAP, PWP)

4. With closed head injury patients need to increase the FIO2 over increasing or adding PEEP

Sigh volume and rate

1. Used to decrease microatelectasis

2. Volume set at double the VT or less (1.5-2 times VT)

3. Rate set at 1-3 sighs every 4-15 minutes

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