Acute Respiratory Failure Flashcards
If the A-a gradient is greater than what mmHg difference; it is indicative of pulmonary dysfunction.
> 20mmHg
What are the three different kinds of Acute Respiratory Failure and what are their causes?
- Hypoxic Respiratory Failure
(Inadequate oxygenation of arterial blood) - Hypercarbic Ventilatory Failure (Insufficient removal of CO2)
- Both
What potential causes could lead to neurologic failure and consequent poor ventilation?
Spinal cord injury *C3, C4, C5* Chest trauma to Phrenic Nerve Neuromuscular blockers Myasthenia gravis Opioids or anesthetics TBI
Diffusion abnormalities occurring at the alveolar level (reduced DLCO) could be caused by what clinical conditions?
Pulmonary Edema
Cardiogenic/Non-Cardiogenic Pulmonary Fibrosis
Interstitial Lung Disease
What is tissue perfusion without ventilation occurring commonly known as?
Shunting
What are some potential causes of shunting?
Alveolar Disease (ARDS Atelectasis Pulmonary Edema Pneumonia)
What is hypercapnia?
What are some potential causes?
Elevated PaCO2 (>45mmHg)
Too much CO2 in blood stream
Result of Obstructive Dz (I.e. COPD, Asthma, CF, or pulm fibrosis)
What is the clinical presentation of Acute Hypercapnia?
Dyspnea Increased HR and BP HA, reduced hearing, hypersomnolence Delirium and dimmed sight Paranoia and/or confusion Myoclonus Asterixis Seizures
(Altered level of consciousness does not appear until >75-80)
ABG: RESPIRATORY ACIDOSIS!
Increased CO2, decreased or normal pH (depending on bicarb compensation)
What is the treatment for a patient suspected of suffering from Acute Hypercapnia?
Increase FiO2 (3-4%/L) of O2
Venturi mask
Non-invasive Pos Pressure Ventilation
What are some of the indications for Pos Pressure Ventilation in a PT?
pH <7.3
Mod-severe respiratory distress
RR > 25
Increased Work of breathing
If a PT is suspected of having Acute Hypercapnia; what Labs and Imaging studies would you consider?
Chem-15 ABG CBC Thyroid panel Tox CXR (Dx lung Dz or Thoracic cage abnormalities) Helical CT or MRI may be indicated
Describe the process of pulmonary edema where the edema begins and where it ends.
Edema begins in the interstitium around the airway –>
- -> then in interstitium around alveoli –>
- -> then in the alveoli
What causes cardiogenic pulmonary edema?
Increased Capillary hydrostatic pressure
What are some causes of Non-Cardiogenic Pulmonary edema?
Increased Capillary PERMEABILITY ARDS HAPE, neurogenic pulm Edema Opioid Overdose Eclampsia
What are some of the clinical manifestations of ARDS?
Acute bilateral alveolar infiltrates Hypoxemia Dyspnea with inc. RR and HR Crackles V/Q mismatch (due to flooded alveoli) Decreased lung compliance (small tidal volume) PULMONARY HTN Confusion, Cyanosis, Diaphoresis
What are some of the most common causes of ARDS?
Pneumonia or Infxn (SARS, bacterial, fungal)
Sepsis (indirect injury) (the rest are direct)
Aspiration (drowning, gastric contents)
Inhalation (smoke, chlorine, NO2)
Trauma
What is the pathology of ARDS?
Alveolar injury recruits interleukins and inflammatory cells.
Damage to epithelium occurs allowing for fluid to rush into interstitium.
Functional surfactant is lost once fluid fills the alveoli
Alveoli collapse
ABG of a PT with ARDS might reveal what?
Respiratory alkalosis with increased A-a gradient. HYPOXEMIA (hallmark S/Sx)
A PT with ARDS may have what findings on CT?
Ground glass infiltrates
Bilat alveolar opacities w/ atelectasis
What CXR criteria helps to rule in ARDS?
NEG cardiomegaly, NEG pleural effusion, NEG Kerley B Lines
POS patchy infiltrates
POS air bronchograms / peribronchial cuffing
In order to make a clinical Dx of ARDS; what must the PT have?
Resp. symptoms x 1 week
Bilat opacities (pulm infiltrates) on CXR / CT
Resp failure not explained by Cardiac failure or fluid overload
HYPOXEMIA on vent (>200, >100, <100 = mild, mod, severe ARDS respectively)
Pulmonary wedge pressure <18mmHg
What is the appropriate treatment for a PT with ARDS? (Hypoxemic, with increased permeability of alveolar-capillary barrier, Pulm edema)
Tx underlying condition PEEP ventilation (Positive End Expiratory Pressure) in PRONE position Manage blood glucose Prophylax for DVT and GI bleeds Eval. for nosocomial pneumonia
Your critically ill PT presents with new onset tachypnea and dyspnea but does not have any consolidation on auscultation. What would should you suspect?
Heart failure or ACUTE RESPIRATORY DISTRESS SYNDROME
