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!
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
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
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