Mark K Lecture 1: Acid-Base Balance & Ventilators

normal values for pH and HCO3

pH: 7.35-7.45

HCO3: 22-26

Rule of Bs

If the pH and the Bicarb are Both in the same direction, then it is metaBolic, otherwise it is respiratory

If the patient is in Alkalosis and the pH is UP, the symptoms would be

As the pH goes, so does my patient:

Everything goes UP in alkalosis with an elevated pH

- tachycardia, tachypnea, HTN, seizures, irritability, spastic, hyperreflexia, borborygmi (increased bowel sounds), diarrhea

INTERVENTION: patient will need suctioning because of seizures

If the patient is in Acidosis and the pH is DOWN the symptoms would be

As the pH goes, so does my patient:

Everything goes DOWN

- bradycardia, constipation, absent bowel sounds, flaccid, obtunded, lethargy, coma, hyporreflexia, bradypena, hypotension

- EXECPT K+ (potassium goes UP in acidosis and patient will have hyperkalemia)

INTERVENTION: patient needs to be ventilated with an ambulance bag

MAC Kussmaul

The only acid base to cause Kussmaul respirations is Metabolic ACidosis

Causes of Acid/ Base imbalance

Is it lung?-> then it is respiratory

Are they over ventilating/ or under ventilating?

If UNDER: pick acidosis

If OVER: pick alkalosis

If it is not lung then it is metabolic

- causes of metabolic alkalosis: prolonged gastric emptying, vomiting, suction

- for everything that isn't lung or alkalosis: pick metabolic acidosis (this is the most common answer for these questions)

High Pressure alarms on Ventilators are triggered by increased resistance to air flow. What should you look for if a high pressure alarm is triggered?

Look for Obstructions!

- kinks in tubing-> unkink

- condensed water in the dependent tube-> empty the water

- mucus plug-> ask patient to turn, cough, deep breathe, or suction the tubing PRN

What is the appropriate order to address high pressure alarm in a mechanical ventilator?

Unkink, empty water out of tubing, turn patient, ask to cough or deep breathe, suction

Low pressure alarms are always triggered by decrease in resistance. What causes the low pressure alarms to be triggered?

- main tubing disconnections

- O2 sensor tube disconnection

- in both cases, reconnect the disconnected tubing unless the tube is on the floor (bag the patient and call RT!)

Ventilator Settings too high and too low-> what are the consequences

Too high: patient is over ventilated

- respiratory alkalosis

Too low: patient is under ventilated

- respiratory acidosis

Ex Question: The physician wants to wean a patient off the vent in the morning. At 6am the ABGs show respiratory acidosis. What should you do?

Notify the physician that the patient is not ready to be weaned off the respirator. The patient is under ventilated and is not ready to be taken off the vent, if he were in respiratory alkalosis he would be under ventilated and would be ready to be taken off.