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Paramedic Rounds
Pre-Hospital Continuous Positive
Airway Pressure (CPAP)
Morgan Hillier MD Class of 2011Dr. Mike Peddle Assistant Medical Director
SWORBHP
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Objectives• Outline evidence for pre-hospital CPAP• Describe normal pulmonary anatomy and physiology
• Describe abnormal pulmonary A&P leading to acute respiratory emergencies
• Describe the mechanism of action of CPAP• Describe the indications, conditions and contraindications for pre-hospital CPAP
• Describe approach to monitoring a patient receiving CPAP and possible complications
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Why CPAP in EMS?
• Hubble MW et all (2006)• Compared to similar EMS systems• System with CPAP protocol showed
• Decreased intubation rate• Decreased mortality• Decreased hospital length of stay
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Why CPAP in EMS?
• Thompson J et al (2008)• Randomized controlled trial• Patients randomized to CPAP treatment group:
• Decreased intubations• Decreased mortality
• No studies have shown evidence of harm
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The Respiratory System
• Architecture of the lung
• similar to an inverted tree-like structure with progressively smaller airways
• Leads to terminal bronchi and • alveoli
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The Respiratory System
• Alveoli• The Functional units of respiration• Contain surfactant
• Liquid which decreases surface tension• Prevents alveoli from “sticking together”
• Alveolar collapse leads to decreased lung volume• Decreased blood oxygen (hypoxemia)• Increased blood CO2 (Hypercarbia)
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The Respiratory System
• Muscles of Respiration• Diaphragm exerts negative pressure on Lungs• Intercostal muscles cause chest excursion• Exhalation is a passive process (elastic recoil)
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The Respiratory System
• Respiratory Distress:• Accessory muscles such as sternocleidomastoids and scalenes increase chest excursion
• At rest, healthy person uses ~4% of oxygen to fuel respiratory muscles
• During acute respiratory emergency, may use up to 20% of oxygen to fuel respiratory effort
• Increased oxygen demand with work of breathing
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Pathophysiology
• Common conditions leading to resp distress:• Cardiogenic Pulmonary Edema• Chronic Obstructive Pulmonary Disease• Asthma• Pneumonia
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Cardiogenic Pulmonary Edema
• Secondary to congestive heart failure (CHF)• Left ventricular failure leads to backward pressure and vascular congestion in lungs
• Increased hydrostatic pressure causes leakage of fluid into alveoli
• Reduces gas exchange leading to hypoxia• “washes out” surfactant leading to alveolar collapse (atelectasis)
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Pulmonary Edema
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Decreased gas exchange due to fluid build up and alveolar collapse
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Acute Pulmonary Edema
• Patient short of breath with increased work of breathing and diffuse inspiratory crackles in all lung fields
• Potentially decreased air entry at bases due to alveolar collapse (atelectasis)
• Patient often has history of coronary artery disease and or cardiac risk factors such as HTN, DM, Hyperlipidemia and family cardiac history
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Chronic Obstructive Pulmonary Disease• Pt has chronic airway disease elicited on history usually with a history of long-term cigarette exposure
• Bronchitis – chronic inflammation characterized by scarring of airways and increased mucous production
• Emphysema – characterized by loss of elasticity of lung parenchyma with destruction of alveoli
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COPD
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COPD Exacerbation
• Usually precipitated by respiratory infection • Acute SOB• Increased work of breathing• Excess secretions (CLEAR productive cough) • Potentially leads to respiratory failure
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Asthma
• Bronchospasm secondary to irritant or allergic stimulus
• Patient presents with • Expiratory wheeze• May progress to insp/expiratory wheeze• Eventually silent chest with no appreciable ventilation to affected area of lungs
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Asthma
• Patient has history of asthma and often a recognized inciting event (“trigger”)
• Treated with bronchodilators and 100% oxygen via NRB mask
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Pneumonia
• Bacterial, viral or fungal infection of the lung• Generally a focal area of infection• Patient presents with
• Fever• productive cough• localized chest pain• focal inspiratory crackles
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Non-Invasive Positive Pressure Ventilation (NIPPV)• Continuous Positive Airway Pressure (CPAP)• Bi-level Positive Airway Pressure (BIPAP)
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How does CPAP work?
• Tight fitting mask controlled by a regulator with high-flow oxygen
• Flow restriction device on exhalation port exerts continuous positive pressure on airways
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Main Effects
• Splints airways open• Positive pressure decreases leakage of fluid into alveoli
• Positive pressure decreases work of breathing and oxygen requirements
• Improves cardiac function by decreasing preload and afterload on the heart
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Cardiogenic Pulmonary Edema
• CPAP:• Decreased leakage of fluid into lungs• Splints airways• Decreases work of breathing/O2 Requirments• Decreases atelectasis
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COPD
• CPAP:• Splints airways• Decreases atelectasis• Decreases work of breathing and oxygen requirements
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Asthma
• CPAP Contraindicated!
• Air-trapping/hyperinflation• Potential to do harm• Focus on bronchodilators and 100% oxygen
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Pneumonia
• CPAP Contraindicated!
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CPAP Indications
• Patient awake and able to follow commands• Meets at least two of the following:
• Resp rate 24 or greater• SpO2 less than 90%• Accessory muscle use
• AND with signs and symptoms consistent with • Exacerbation of chronic obstructive pulmonary disease OR
• Acute pulmonary edema
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CPAP Conditions
• Age 12 years or greaterOR• Weight 40Kg or greater
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CPAP Contraindications
• Resp distress due to other medical condition• Asthma• Pneumonia
• Condition that may be worsened by CPAP• Pneumothorax• Systolic BP <90• Major trauma or burns (face, neck, chest, abdo)
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CPAP Contraindications
• Other intervention required• Unable to cooperate, decreased mentation, inability to sit upright
• Unable to maintain airway, intubated patient, facial abnormality, tracheostomy
• Resp rate < 8• Cardiac arrest
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Patient Monitoring
• Assess for:• Decreased Respiratory Rate• Increased SpO2• Subjective improvement in dyspnea• Decreased anxiety
• Vitals q5min with particular attention to:• Blood pressure• Adequacy of ventilation
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Complications
• Hypotension• Conversion of pneumo to tension pneumo• Airway obstruction• Requires continuous oxygen supply• Relies on patients respiratory rate• Intolerance of mask • Vitals q5min and constant patient monitoring!
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Questions???
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