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What Pam Learned At the CSRT Conference Quebec City June 9-12, 2011.

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Presentation on theme: "What Pam Learned At the CSRT Conference Quebec City June 9-12, 2011."— Presentation transcript:

1 What Pam Learned At the CSRT Conference Quebec City June 9-12, 2011

2 Objectives  Sleep During Mechanical Ventilation  ABG Challenge: Classification vs. Interpretation  And I learned a lot more than that…

3 Sleeping During Mechanical Ventilation  Altered sleep patterns in ventilated patients can delay their weaning  The average sleep time of a ventilated patient is the same as you or I, but the quality of sleep is reduced  Stage 1 and 2 of sleep is a light sleep leading into Stage 3 and 4 which is deep non-REM sleep vital for psychological recovery  REM sleep is vital for physical recovery  Sleep at each stage for a healthy person is: 20% in Stages 1 and 2, 30% in Stages 3 and 4, 50% in REM sleep  Ventilated patients will spend 45% of their sleep time in Stages 1 and 2 of sleep and 25% of their sleep is in REM sleep  Less REM sleep means less physical recovery


5 Sleep During Mechanical Ventilation  There are many reasons for sleeplessness in the ICU including:  Noise (Surprise! Increases in decibels bother people)  Lighting (Our lights are always on somewhere)  Stress and Pain  Bad Sedation  ICU Psychosis  Interventions in the middle of the night (bathing, shaving or suctioning)  In Ventilated patients: Ventilator asynchrony

6 Vent Asynchrony Affecting Sleep  If your patient is not comfortable on the ventilator they will rouse  ¼ of patients suffer from asynchrony  Studies have proven, though, that patients rested at night on PSV, roused more often than patients on AC, although there is no change to the amount of time spent in the different stages of sleep  WHY?!  Apnea, of course!  Patients on AC ventilation still roused due to ventilator asynchrony – they were unable to trigger the vent

7 So what mode do I put my patient on so he can rest?  Studies have shown that it is not necessary to control a patients ventilation for them to rest at night  AND increasing PSV at night can increase Central Apneas by over-ventilating causing more arousals  What we need is a ventilator mode that can adjust to the patients needs while they are sleeping such as NAVA  NAVA: Neurally Adjusted Ventilatory Assist  Involves a nasogastric catheter with electrodes buried to the level of the diaphragm that picks up electrical activity to the diaphragm and causes the ventilator to respond appropriately according to the patients needs  ** Of course, if you don’t have access to NAVA, use PSV or PAV with an optimal support to ensure tidal volume of 6ml/kg IBW **

8 NAVA  Having NAVA in our hospital would require the purchase of a Servo-i ventilator  But just to prove a point, here’s how effective using NAVA was compared to PSV  NAVA patients received less Stage 1 and 2 sleep compared to PSV  NAVA patients received more Stage 3, 4 and REM sleep compared to PSV  NAVA eliminates ventilator asynchrony and prevents overventilation  NAVA allows for the variability in ventilation of the human body from wakefulness to sleep

9 ABG Challenge: Classification vs. Interpretation  We were all taught in school that interpreting ABG’s was a lot deeper than uncompensated, compensated, metabolic, respiratory, acidosis, alkalosis  We have forgotten it all!

10 Noooo not school again!

11 Problem pH 7.12 pCO 2 42 HCO 3 - 13 PaO 2 60 Interpretation?

12 Answer Uncompensated Metabolic Acidosis (Lungs are not compensating) Mild Hypoxemia You’re not wrong, but you haven’t interpreted the ABG, only classified it

13 Classifying does NOT equal Interpretation TTTThere are 3 steps involved in interpreting an ABG Don’t worry it’s not that scary

14 Steps to Interpreting an ABG 1.Classification (check, got that down) 2.Calculations  Determines whether or not the body is compensating and if there are other existing disorders 3.Confirmation  Does it match the patient assessment and baseline.  Check for accuracy

15 I Hate to Tell You… Problem: pH 7.12/CO 2 42/HCO 3 - 13 That’s not just an Uncompensated Metabolic Acidosis Remember the calculations we were taught in school? For every 1 point bicarbonate drop, pH should drop 0.015

16  Problem:  Focus on bicarbonate  Bicarb has dropped 11 points (24 – 13 = 11)  pH should drop to maximum 7.23 (11 x 0.015 = 0.165; 7.40 – 0.165 = 7.235)  CO2 should drop to 27  But our values are 7.12 with a CO2 of 42  What gives?! Calculations

17 Here’s a Quick Reference Chart for people who don’t want to do the math

18  The CO2 should be lower as the patient blows off CO2 to try to compensate for the metabolic acidosis  CO2 should be 27 and the pH 7.23  In this case, our patient is not hyperventilating as he should  He has tired out from hyperventilating and is now in Ventilatory Failure  We have a DOUBLE DISORDER *cue dramatic music*  Not only is the patient in a metabolic acidosis, but his lungs are adding to the problem – respiratory acidosis  The CO2 value was probably lower at one point, but as the patient begins to fail, the CO2 rises and we happened to collect this gas at a time when the CO2 was in the normal range

19 BUT WAIT, We’re Not Done  There are other calculations we can do to indicate a THIRD DISORDER from a blood gas.  Anion Gap (remember that?)  Anion gap helps to identify the presence of Metabolic acidosis and the type of metabolic acidosis  When we know the type (Anion gap or non- anion gap) we can determine the cause

20 Anion Gap  We all know how to calculate anion gap  Na + - (Cl - + HCO 3 - )  A normal anion gap is 12mEq/L (thereabouts)  If this value is <12, you have a non-anion gap acidosis  If this value is >12, you have an anion gap acidosis  There are numerous reasons to have an anion gap acidosis

21 Quick example  58 yo female presents with pneumonia, hypotension, nausea and vomiting x3 days  pH 7.25/CO2 15/HCO3- 10 PaO2 76  Na+ 130 Cl- 90  Classification: Partially compensated (Chronic) Metabolic Acidosis  Based on the quick reference chart with bicarb of 10, pH should be 7.19 with CO2 23  We know now that this is a mixed Metabolic Acidosis with Respiratory Alkalosis


23  Add the anion gap calculation in:  130 – (90 + 10) = 30  We’ve proven that this patient has an anion gap metabolic acidosis  Some Triple Disorders can have a Metabolic Alkalosis mixed with an Anion Gap Metabolic Acidosis

24 Confirmation: Check your interpretation against the patient assessment and history Check for accuracy Anion Gap Met. Acid explained by the Pneumonia and consequent Sepsis Respiratory Alkalosis explained by hyperventilation due to hypoxemia Metabolic Alkalosis explained by the vomiting


26 Got It?

27 Other Things I Learned  Lung Expansion and Airway Clearance (MetaNeb system)  Clinical Use of Transpulmonary Pressures (kind of like beating a dead horse, but really quite interesting)  How to Manage Ventilator Asynchrony

28 CSRT Conference 2012 Vancouver

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