What Pam Learned At What Pam Learned At the CSRT Conferencethe CSRT Conference

Quebec City June 9-12, 2011Quebec City June 9-12, 2011

ObjectivesObjectives

Sleep During Mechanical Sleep During Mechanical VentilationVentilation

ABG Challenge: Classification ABG Challenge: Classification vs. Interpretationvs. Interpretation

And I learned a lot more than And I learned a lot more than that…that…

Sleeping During Sleeping During Mechanical VentilationMechanical Ventilation Altered sleep patterns in ventilated patients can delay their Altered sleep patterns in ventilated patients can delay their

weaningweaning The average sleep time of a ventilated patient is the same as you The average sleep time of a ventilated patient is the same as you

or I, but the quality of sleep is reducedor I, but the quality of sleep is reduced Stage 1 and 2 of sleep is a light sleep leading into Stage 3 and 4 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 recoverywhich is deep non-REM sleep vital for psychological recovery REM sleep is vital for physical recoveryREM sleep is vital for physical recovery Sleep at each stage for a healthy person is: 20% in Stages 1 and Sleep at each stage for a healthy person is: 20% in Stages 1 and

2, 30% in Stages 3 and 4, 50% in REM sleep2, 30% in Stages 3 and 4, 50% in REM sleep Ventilated patients will spend 45% of their sleep time in Stages 1 Ventilated patients will spend 45% of their sleep time in Stages 1

and 2 of sleep and 25% of their sleep is in REM sleepand 2 of sleep and 25% of their sleep is in REM sleep Less REM sleep means less physical recoveryLess REM sleep means less physical recovery

Sleep During Mechanical Sleep During Mechanical VentilationVentilation

There are many reasons for sleeplessness in the ICU There are many reasons for sleeplessness in the ICU including:including: Noise (Surprise! Increases in decibels bother people)Noise (Surprise! Increases in decibels bother people) Lighting (Our lights are always on somewhere)Lighting (Our lights are always on somewhere) Stress and PainStress and Pain Bad SedationBad Sedation ICU PsychosisICU Psychosis Interventions in the middle of the night (bathing, Interventions in the middle of the night (bathing,

shaving or suctioning)shaving or suctioning) In Ventilated patients: Ventilator asynchronyIn Ventilated patients: Ventilator asynchrony

Vent Asynchrony Affecting SleepVent Asynchrony Affecting Sleep

If your patient is not comfortable on the ventilator they If your patient is not comfortable on the ventilator they will rousewill rouse

¼ of patients suffer from asynchrony¼ of patients suffer from asynchrony Studies have proven, though, that patients rested at Studies have proven, though, that patients rested at

night on PSV, roused more often than patients on AC, night on PSV, roused more often than patients on AC, although there is no change to the amount of time spent although there is no change to the amount of time spent in the different stages of sleepin the different stages of sleep

WHY?!WHY?! Apnea, of course!Apnea, of course! Patients on AC ventilation still roused due to ventilator Patients on AC ventilation still roused due to ventilator

asynchrony – they were unable to trigger the ventasynchrony – they were unable to trigger the vent

So what mode do I put my patient So what mode do I put my patient on so he can rest?on so he can rest? Studies have shown that it is not necessary to control a Studies have shown that it is not necessary to control a

patients ventilation for them to rest at nightpatients ventilation for them to rest at night AND increasing PSV at night can increase Central Apneas AND increasing PSV at night can increase Central Apneas

by over-ventilating causing more arousalsby over-ventilating causing more arousals What we need is a ventilator mode that can adjust to the What we need is a ventilator mode that can adjust to the

patients needs while they are sleeping such as NAVApatients needs while they are sleeping such as NAVA NAVA: Neurally Adjusted Ventilatory AssistNAVA: Neurally Adjusted Ventilatory Assist Involves a nasogastric catheter with electrodes buried to Involves a nasogastric catheter with electrodes buried to

the level of the diaphragm that picks up electrical activity the level of the diaphragm that picks up electrical activity to the diaphragm and causes the ventilator to respond to the diaphragm and causes the ventilator to respond appropriately according to the patients needsappropriately according to the patients needs

** Of course, if you don’t have access to NAVA, use PSV ** Of course, if you don’t have access to NAVA, use PSV or PAV with an optimal support to ensure tidal volume of or PAV with an optimal support to ensure tidal volume of 6ml/kg IBW **6ml/kg IBW **

NAVANAVA Having NAVA in our hospital would require the Having NAVA in our hospital would require the

purchase of a Servo-i ventilatorpurchase of a Servo-i ventilator But just to prove a point, here’s how effective using But just to prove a point, here’s how effective using

NAVA was compared to PSVNAVA was compared to PSV NAVA patients received less Stage 1 and 2 sleep NAVA patients received less Stage 1 and 2 sleep

compared to PSVcompared to PSV NAVA patients received more Stage 3, 4 and REM sleep NAVA patients received more Stage 3, 4 and REM sleep

compared to PSVcompared to PSV NAVA eliminates ventilator asynchrony and prevents NAVA eliminates ventilator asynchrony and prevents

overventilationoverventilation NAVA allows for the variability in ventilation of the NAVA allows for the variability in ventilation of the

human body from wakefulness to sleephuman body from wakefulness to sleep

ABG Challenge: Classification ABG Challenge: Classification vs. Interpretationvs. Interpretation

We were all taught in school that We were all taught in school that interpreting ABG’s was a lot deeper interpreting ABG’s was a lot deeper than uncompensated, than uncompensated, compensated, metabolic, compensated, metabolic, respiratory, acidosis, alkalosisrespiratory, acidosis, alkalosis

We have forgotten it all!We have forgotten it all!

Noooo not school again!Noooo not school again!

ProblemProblem

pH 7.12pH 7.12

pCOpCO22 42 42

HCOHCO33-- 13 13

PaOPaO22 60 60

Interpretation?Interpretation?

AnswerAnswer

Uncompensated Metabolic AcidosisUncompensated Metabolic Acidosis(Lungs are not compensating)(Lungs are not compensating)

Mild HypoxemiaMild Hypoxemia

You’re not wrong, but you haven’t You’re not wrong, but you haven’t interpreted the ABG, only classified itinterpreted the ABG, only classified it

Classifying does NOT Classifying does NOT equal Interpretationequal Interpretation

There are 3 steps involved in interpreting an ABGThere are 3 steps involved in interpreting an ABG

Don’t Don’t worry worry it’s not it’s not that that scaryscary

Steps to Interpreting an ABGSteps to Interpreting an ABG

1.1. Classification (check, got that down)Classification (check, got that down)

2.2. CalculationsCalculations Determines whether or not the body is Determines whether or not the body is

compensating and if there are other existing compensating and if there are other existing disordersdisorders

3.3. ConfirmationConfirmation Does it match the patient assessment and Does it match the patient assessment and

baseline. baseline. Check for accuracyCheck for accuracy

I Hate to Tell You…I Hate to Tell You…

Problem: pH 7.12/COProblem: pH 7.12/CO22 42/HCO 42/HCO33-- 13 13

That’s not just an Uncompensated Metabolic That’s not just an Uncompensated Metabolic AcidosisAcidosis

Remember the calculations we were taught in school?

For every 1 point bicarbonate drop, pH should drop 0.015

Problem: Problem: Focus on bicarbonateFocus on bicarbonate Bicarb has dropped 11 points (24 – 13 = 11)Bicarb has dropped 11 points (24 – 13 = 11) pH should drop to maximum 7.23 (11 x 0.015 = pH should drop to maximum 7.23 (11 x 0.015 =

0.165; 7.40 – 0.165 = 7.235)0.165; 7.40 – 0.165 = 7.235) CO2 should drop to 27 CO2 should drop to 27 But our values are 7.12 with a CO2 of 42But our values are 7.12 with a CO2 of 42 What gives?!What gives?!

CalculationsCalculations

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

The CO2 should be lower as the patient blows off CO2 to The CO2 should be lower as the patient blows off CO2 to try to compensate for the metabolic acidosistry to compensate for the metabolic acidosis

CO2 should be 27 and the pH 7.23CO2 should be 27 and the pH 7.23 In this case, our patient is not hyperventilating as he shouldIn this case, our patient is not hyperventilating as he should He has tired out from hyperventilating and is now in He has tired out from hyperventilating and is now in

Ventilatory FailureVentilatory Failure We have a DOUBLE DISORDERWe have a DOUBLE DISORDER

*cue dramatic music**cue dramatic music* Not only is the patient in a metabolic acidosis, but his lungs Not only is the patient in a metabolic acidosis, but his lungs

are adding to the problem – respiratory acidosisare adding to the problem – respiratory acidosis The CO2 value was probably lower at one point, but as the The CO2 value was probably lower at one point, but as the

patient begins to fail, the CO2 rises and we happened to patient begins to fail, the CO2 rises and we happened to collect this gas at a time when the CO2 was in the normal collect this gas at a time when the CO2 was in the normal rangerange

BUT WAIT, We’re Not BUT WAIT, We’re Not DoneDone There are other calculations we can do to There are other calculations we can do to

indicate a THIRD DISORDER from a blood indicate a THIRD DISORDER from a blood gas.gas.

Anion Gap (remember that?)Anion Gap (remember that?) Anion gap helps to identify the presence of Anion gap helps to identify the presence of

Metabolic acidosis and the type of Metabolic acidosis and the type of metabolic acidosismetabolic acidosis

When we know the type (Anion gap or non-When we know the type (Anion gap or non-anion gap) we can determine the causeanion gap) we can determine the cause

Anion GapAnion Gap We all know how to calculate anion gapWe all know how to calculate anion gap

NaNa++ - (Cl - (Cl-- + HCO + HCO33--))

A normal anion gap is 12mEq/L A normal anion gap is 12mEq/L (thereabouts)(thereabouts)

If this value is <12, you have a non-anion If this value is <12, you have a non-anion gap acidosisgap acidosis

If this value is >12, you have an anion gap If this value is >12, you have an anion gap acidosisacidosis

There are numerous reasons to have an There are numerous reasons to have an anion gap acidosisanion gap acidosis

Quick exampleQuick example 58 yo female presents with pneumonia, 58 yo female presents with pneumonia,

hypotension, nausea and vomiting x3 dayshypotension, nausea and vomiting x3 days pH 7.25/CO2 15/HCO3- 10 PaO2 76pH 7.25/CO2 15/HCO3- 10 PaO2 76 Na+ 130 Cl- 90Na+ 130 Cl- 90 Classification: Partially compensated Classification: Partially compensated

(Chronic) Metabolic Acidosis(Chronic) Metabolic Acidosis Based on the quick reference chart with Based on the quick reference chart with

bicarb of 10, pH should be 7.19 with CO2 23bicarb of 10, pH should be 7.19 with CO2 23 We know now that this is a mixed Metabolic We know now that this is a mixed Metabolic

Acidosis with Respiratory AlkalosisAcidosis with Respiratory Alkalosis

Add the anion gap calculation in:Add the anion gap calculation in: 130 – (90 + 10) = 30130 – (90 + 10) = 30 We’ve proven that this patient has an anion We’ve proven that this patient has an anion

gap metabolic acidosis gap metabolic acidosis

Some Triple Disorders can have a Some Triple Disorders can have a Metabolic Alkalosis mixed with an Anion Metabolic Alkalosis mixed with an Anion Gap Metabolic AcidosisGap Metabolic Acidosis

Confirmation:Confirmation:Check your interpretation Check your interpretation

against the patient against the patient assessment and historyassessment and history

Check for accuracyCheck for accuracyAnion Gap Met. Acid explained by the Pneumonia and Anion Gap Met. Acid explained by the Pneumonia and consequent Sepsisconsequent Sepsis

Respiratory Alkalosis explained by hyperventilation due to Respiratory Alkalosis explained by hyperventilation due to hypoxemiahypoxemia

Metabolic Alkalosis explained by the vomitingMetabolic Alkalosis explained by the vomiting

Remember:Remember:TREAT THE PATIENT, TREAT THE PATIENT, NOT THE ABGNOT THE ABG

Got It?Got It?

Other Things I LearnedOther Things I Learned

Lung Expansion and Airway Clearance Lung Expansion and Airway Clearance (MetaNeb system)(MetaNeb system)

Clinical Use of Transpulmonary Pressures Clinical Use of Transpulmonary Pressures (kind of like beating a dead horse, but (kind of like beating a dead horse, but really quite interesting)really quite interesting)

How to Manage Ventilator AsynchronyHow to Manage Ventilator Asynchrony

CSRT Conference CSRT Conference 20122012

VancouverVancouver