Respiratory Failure – COPD Respiratory Failure – COPD and Asthmaand Asthma

59 year old man presents to the ER with a 59 year old man presents to the ER with a 3 day history of progressively worsening 3 day history of progressively worsening shortness of breath.shortness of breath.

He has a past history of chronic lung He has a past history of chronic lung disease that started about 5 years ago and disease that started about 5 years ago and he is an ex-smoker for about 6 months he is an ex-smoker for about 6 months since his family doctor threatened to put since his family doctor threatened to put him on home oxygen.him on home oxygen.

What additional information do you want on What additional information do you want on history?history?The patient states that he has had a chronic The patient states that he has had a chronic productive cough for years and over the last productive cough for years and over the last week he has noticed a changed in the amount week he has noticed a changed in the amount and color of his sputum.and color of his sputum.Denies any recent travel, sick contacts (although Denies any recent travel, sick contacts (although grandkids visited about 10 days ago), fevers, grandkids visited about 10 days ago), fevers, chest pain, orthopnea, past hospitalizations or chest pain, orthopnea, past hospitalizations or surgeries.surgeries.Still works as an accountant.Still works as an accountant.

Initial CXRInitial CXR

On examination, his chest sounds are distant On examination, his chest sounds are distant with some wheeze and prolonged exhalation. with some wheeze and prolonged exhalation. Heart sounds are difficult to hear.Heart sounds are difficult to hear.

He is unable to speak in complete sentences He is unable to speak in complete sentences and is in moderate to severe respiratory distress.and is in moderate to severe respiratory distress.

Room air ABG: pH 7.19, PCO2 76, PO2 53, Room air ABG: pH 7.19, PCO2 76, PO2 53, HCO3 35HCO3 35

WBC 12.7, Bands 9%, Hgb 186, Platelets 250WBC 12.7, Bands 9%, Hgb 186, Platelets 250

What is the most likely diagnosis?What is the most likely diagnosis?

What is the differential diagnosis?What is the differential diagnosis?

Why is the PCO2 elevated?Why is the PCO2 elevated?– What are the determinants of blood CO2 What are the determinants of blood CO2

concentrations?concentrations?– What is dead space ventilation and what is the What is dead space ventilation and what is the

difference between anatomical and physiological difference between anatomical and physiological dead space? dead space?

– How is dead space ventilation different from shunt?How is dead space ventilation different from shunt?

Why is the PO2 low?Why is the PO2 low?

What are the factors that influence What are the factors that influence respiratory muscle strength?respiratory muscle strength?– Consider:Consider:

FatigueFatigue

MalnutritionMalnutrition

HypoperfusionHypoperfusion

MyopathyMyopathy

SteroidsSteroids

Electrolyte derangementsElectrolyte derangements

What are the factors that influence respiratory What are the factors that influence respiratory muscle load?muscle load?– Consider:Consider:

BronchospasmBronchospasm

SecretionsSecretions

Dynamic hyperinflationDynamic hyperinflation

AtelectasisAtelectasis

Increase CO2 productionIncrease CO2 production

InfectionInfection

PneumothoraxPneumothorax

Abdominal distensionAbdominal distension

What is the relationship between What is the relationship between respiratory muscle strength and load in respiratory muscle strength and load in acute on chronic respiratory failure?acute on chronic respiratory failure?

The patient’s respiratory distress has not The patient’s respiratory distress has not improved with all of this physiology talk.improved with all of this physiology talk.

What is the approach to the treatment of What is the approach to the treatment of acute on chronic respiratory failure in the acute on chronic respiratory failure in the emergency department?emergency department?

After starting frequent bronchodilators, After starting frequent bronchodilators, steroids and empiric antibiotics, the patient steroids and empiric antibiotics, the patient is not feeling better.is not feeling better.What is the role for non-invasive positive What is the role for non-invasive positive pressure ventilation for this problem?pressure ventilation for this problem?What are the indications and What are the indications and contraindications for NIPPV?contraindications for NIPPV?How does NIPPV work in acute on chronic How does NIPPV work in acute on chronic respiratory failure?respiratory failure?

After applying NIPPV, the patient begins to After applying NIPPV, the patient begins to feel better and eventually is transferred to feel better and eventually is transferred to the ward.the ward.If he had not improved, how would you If he had not improved, how would you know and what would you do?know and what would you do?Bonus question: What causes the PCO2 Bonus question: What causes the PCO2 to rise on high flow oxygen? How to rise on high flow oxygen? How common is it? Which is more harmful; common is it? Which is more harmful; hypercarbia or hypoxemia?hypercarbia or hypoxemia?

Next Case…Next Case…

19 year old woman with a 12 year history of 19 year old woman with a 12 year history of asthma presents to the ER with 3 day history of asthma presents to the ER with 3 day history of increasing shortness of breath and cough.increasing shortness of breath and cough.

She recently rescued a cat from the pound and She recently rescued a cat from the pound and started dating a boy who smokes.started dating a boy who smokes.

She has been to the ER about one per year for She has been to the ER about one per year for asthma attacks, admitted twice and never in asthma attacks, admitted twice and never in ICU.ICU.

She uses ventolin about 6 times per day.She uses ventolin about 6 times per day.

On examination, she is in severe On examination, she is in severe respiratory distress with a rate of 31, pulse respiratory distress with a rate of 31, pulse 124, and O2 saturations of 100% on face 124, and O2 saturations of 100% on face mask.mask.Her blood pressure is 151/83 with a pulsus Her blood pressure is 151/83 with a pulsus paradoxus of 25.paradoxus of 25.What is a pulsus paradoxus?What is a pulsus paradoxus?If her pulsus was 15, would you be If her pulsus was 15, would you be reassured? reassured?

What investigations would you order?What investigations would you order?What treatments would you order?What treatments would you order?What is the role of heliox and non-invasive What is the role of heliox and non-invasive positive pressure ventilation in severe positive pressure ventilation in severe asthma?asthma?Her ABG on face mask is: pH 7.20, PCO2 Her ABG on face mask is: pH 7.20, PCO2 35, PO2 123, HCO3 1735, PO2 123, HCO3 17Is this a reassuring ABG? Why or why Is this a reassuring ABG? Why or why not?not?

CXRCXR

After 35 minutes of continuous therapy, After 35 minutes of continuous therapy, her work of breathing is about the same, her work of breathing is about the same, she can speak in short words only and is she can speak in short words only and is becoming difficult to arouse.becoming difficult to arouse.

What do you do next?What do you do next?

What are the indications for intubation in What are the indications for intubation in severe asthma?severe asthma?

She is successfully intubated on the first She is successfully intubated on the first attempt. Immediately after her blood pressure attempt. Immediately after her blood pressure starts to fall and she becomes pulseless but the starts to fall and she becomes pulseless but the monitor still shows electrical activity.monitor still shows electrical activity.What could be causing this PEA arrest?What could be causing this PEA arrest?– Consider:Consider:

HypovolemiaHypovolemiaLoss of vascular toneLoss of vascular tonePneumothoraxPneumothoraxElectrolyte disorders; especially pHElectrolyte disorders; especially pHOverventilation on the Ambu BagOverventilation on the Ambu Bag

The RT reports that she is very stiff to bag The RT reports that she is very stiff to bag but after disconnecting her from the bag but after disconnecting her from the bag and waiting 30 seconds, she regains a and waiting 30 seconds, she regains a pulse.pulse.

What is dynamic hyperinflation?What is dynamic hyperinflation?

What are the consequences of dynamic What are the consequences of dynamic hyperinflation?hyperinflation?

Now that she is on the ventilator and more Now that she is on the ventilator and more stable, what treatments would you use for stable, what treatments would you use for her asthma?her asthma?

How would you ventilate her?How would you ventilate her?

Despite permissive hypercarbia, she is still Despite permissive hypercarbia, she is still difficult to ventilate?difficult to ventilate?

What other treatments are available?What other treatments are available?

Question??Question??