4TerminologyHeart Failure: The inability of the heart to maintain an output adequate to maintain the metabolic demands of the body.Pulmonary Edema: An abnormal accumulation of fluid in the lungs.CHF with Acute Pulmonary Edema: Pulmonary Edema due to Heart Failure (Cardiogenic Pulmonary Edema)
30EMS Management Sit upright High Flow O2 Nitroglycerine (If SBP > 100)MorphineDiuretics (furosemide)Ventilatory SupportCPAPBVMIntubation and ventilation
31Pharmacological Treatment: Nitroglycerine (NTG)Relaxes arteries and veins0.4 mg sub lingual or 1 sprayRepeat x2 every 5 min if SBP > 100Consider 1” NTG paste to CW
32Pharmacological Treatment: MorphineAlso relaxes arteries and veinsReduces anxiety and O2 demand2-4 mg IV
33Pharmacological Treatment: Furosemide (Lasix)A diuretic, reducing fluid overloadRequires good enough cardiac output to reach the kidneys40mg IVMay require more if already taking Lasix
34Beta Blockers (Lopressor)??? Pharmacological Treatment:Beta Blockers (Lopressor)???Not useful in acute CHFDecrease HR and output, worsening failureMay cause/worsen bronchoconstrictionHowever they are used in stable, compensated failure so they may be on a pt’s med list
35Continuous Positive Airway Pressure Ventilatory Support:CPAPContinuous Positive Airway PressureCPAP: Continuous Positive Airway PressureThe term ‘continuous positive airway pressure’ was coined in 1971 by Gregory et al to describe an elevated airway pressure therapy for spontaneously breathing, intubated neonates.Current application has expanded to include adults and more recently patients without an artificial airway.‘The application of positive airway pressure throughout the whole respiratory cycle to spontaneously breathing patients’ (Keilty et al. 1992).
36CPAP is oxygen therapy in its most efficient form. Simple MasksVenturi MasksCPAPCPAP IS OXYGEN THERAPY IN ITS MOST EFFICIENT FORMMedium concentration oxygen mask:Unable to deliver an accurate oxygen % since the patientinspiratory flow is not taken into account.Venturi mask:Deliver accurate concentrations at 24%, 28%, 35%, 40%, 60%;however, the higher the % the greater the necessity to humidifyespecially long term use.Humidified Oxygen:Able to deliver up to 60% O2, but only accurate up to a PeakInspiratory Flow Rate (PIFR) of 22 Lpm above which the % is dilutedaccording to the patient’s demand.CPAP:The only system capable of delivering up to 100% humidifiedoxygen at flow rates of up to 140 Lpm, thus satisfying all clinicalrequirements.
37Why does oxygen pass into the blood? The Pressure GradientDeoxygenated blood has a lower partial pressure of oxygen so oxygen transfers from the air into the blood.The blood supply arriving at the alveoli carries deoxygenated blood.This means that the oxygen has been used as the blood has beencirculated round the body.Oxygen passes from the alveolar air into the blood because the partialpressure of oxygen in the alveolar air is higher than that in the bloodarriving at the lungsIt also applies the other way too! Blood arriving at the lungs has a higherpartial pressure of carbon dioxide than the alveolar air, hence CO2 leaves the blood and is expired.
38CPAP and Patient Airway Pressure PATIENT AIRWAY PRESSURESThis slide illustrates simulated breath traces at atmospheric pressure (0cm H2O), and at 5cm H2O CPAP.Note that for inhalation of air to occur when breathing without assistance (0cm H2O), the generation of a pressure gradient is required: the pressure within the lungs is negative compared to that in the atmosphere, and consequently air is drawn into the lungs.Conversely, during exhalation, the passive elastic recoil of the ribcage elevates the intrathoracic pressure to above the atmospheric level and is therefore positive, consequently forcing air out of the lungs.The larger the drop in pressure on inhalation (i.e. the more negative it gets) the greater the patient work of breathing.When breathing with the aid of CPAP, the pressure within the lungs always remains positive.‘The application of positive airway pressure throughout the wholerespiratory cycle to spontaneously breathing patients.
39CPAP increases the pressure gradient 7.5cm H2O CPAP increases the partial pressure of the alveolar air by approximately 1%.This increase in partial pressure ‘forces’ more oxygen into the blood.Even this comparatively small change is enough to make a clinical difference.1 cm H2O is equal to mm Hg.A 7.5cm H2O C.P.A.P. valve increases atmospheric pressure at sea levelby 5.51mm Hg, and this in turn increases the partial pressure of thealveolar air by approximately 1%.This increase in partial pressure ‘forces’ more oxygen into the blood.Even this comparatively small change is enough to make a clinical difference.
40Physiological Effects Of CPAP Increases the volume of gas remaining in lungs at end-expirationCPAP distends alveoli preventing collapse on expirationGreater surface area improves gas exchangeReduces work of breathingPHYSIOLOGICAL EFFECTS OF CPAP.Increases FRCReduces Patient Work of BreathingReduces V/Q Mismatch and ShuntThe positive pressure increases the volume of air left in the lungs at the end of expiration. CPAP provides an increase in FRC (Gherini 1976).As a result of the increase in FRC additional areas of lung are recruited into the gas exchange process and allows an improvement in blood gas values.Since CPAP shifts the lung volume along the compliance curve it reduces the patient work of breathing.In addition, as more alveoli now participate in the gas exchange process the V/Q mismatch is corrected and the fraction of shunt is reduced.
42CPAP And Pulmonary Edema CPAP increases transpulmonary pressureCPAP improves lung complianceCPAP improves arterial blood oxygenationCPAP redistributes extravascular lung waterCPAP AND PULMONARY odema.Severe pulmonary odema is a frequent cause of respiratory failure.CPAP increases FRC.CPAP increases transpulmonary pressure.CPAP improves lung compliance.10 cm CPAP improves arterial blood oxygenation.CPAP redistributes extravascular lung water.
43Redistribution Of Extravascular Lung Water With CPAP REDISTRIBUTION OF EXTRAVASCULAR LUNG WATER WITH PEEP.The application of PEEP to the edematous lung decreases intra-alveolar fluid volume, increases interstitial lung water, and facilitates the movement of water from the less compliant interstitial spaces where gas exchange occurs to the more compliant interstitial spaces.This redistribution of interstitial water improves oxygenation, lung compliance, and ventilation/perfusion matching when applied in either cardiogenic or non-cardiogenic pulmonary odema.
44CPAP And Acute Respiratory Failure CPAP prevents airway collapse during exhalationCPAP overcomes inspiratory work imposed by auto-peep (pursed lip breathing)CPAP may avoid intubation and mechanical ventilationCPAP AND ACUTE RESPIRATORY FAILURE.CPAP overcomes inspiratory work imposed by auto-PEEP.CPAP prevents airway collapse during exhalation and has the effect of ‘splinting the airways’CPAP improves arterial blood gas values.CPAP may avoid intubation and mechanical ventilation.(Miro 1993)
45Caution COPD and Asthmatic patients do not respond predictably to CPAP Higher risk of complications such as pneumothorax
46When Not To Use Mask CPAP Pneumothorax (evolve into tension)Hypovolemia (further limit preload)Severe facial injuriesPatients at risk of vomitingCONTRA-INDICATIONS OF MASK CPAP.Hypercapnic patients may have a reversed respiratory drive, and rely on low levels of oxygen to trigger a breath rather than the much more sensitive trigger of CO2 active in normal subjects. A patient whose respiratory drive is now sensitive only to low levels of oxygen must not therefore be administered oxygen as this will knock out the respiratory drive and as a result lead to a reduction of the respiratory rate, with the consequent elevation of PaCO2.CPAP should not be used with patients with an undrained pheumothorax.An emphysematous bulla within the lungs presents a risk when any type of positive airway pressure is applied to the lungs. A bulla is a large area of the lungs that has broken down to form a hole. Bullae are very brittle and present a risk of bursting.Hypovolemia is a low blood volume. Administering CPAP may reduce both blood pressures and cardiac output.Although no true contra-indications have been identified in the literature, CPAP should not be administered to patients with unstable facial fractures, excessive facial lacerations, laryngeal trauma, or a recent tracheal or esophageal anastomosis.Patients at risk of vomiting (those with gastrointestinal bleeding or ileus) may also need to be excluded.
47Common Complications With CPAP Gastric distensionPulmonary barotraumaReduced cardiac outputHypoventilationCOMMON COMPLICATIONS ASSOCIATED WITH CPAP.1. Pressure Sores - Since the advent of soft, self-sealing masks, these complications are usually limited to nasal-bridge pain and erythema at the site of application. However these symptoms can be reduced by the prior application of materials such as “Granuflex”. Another less serious complication of the mask is patient discomfort or intolerance.2. Gastric Distension - The most significant potential complication cited by early critics were aerophagia and aspiration of gastric contents. However, the levels of CPAP used (<10 cm H2O) are usually not associated with gastric distension. If this complication occurs, it is easily remedied by naso-gastric intubation, with regular aspiration. Gastric aspiration related to CPAP via face mask has never been reported in the literature.3. Pulmonary Barotrauma - With mask CPAP, as with any positive-pressure therapy, the potential for distension and pulmonary barotrauma is always present. However, in investigations cited by Branson (1985) only one of 196 patients developed evidence of barotrauma (pneumomediastinum), representing a complication rate of 0.5%. The low incidence of barotrauma in these patients may be attributed to the use of spontaneous breathing as the method of ventilatory support. To further minimise this risk the status of the patient’s lung disease should be considered when prescribing CPAP.4. Reduced Cardiac Output - Positive-pressure therapy has been associated with a decrease in cardiac output by Gong (1983). However, heamodynamic embarrassment in patients treated with the levels of CPAP described in that report was most often due to hypovolemia. In Branson’s report cardiovascular depression did not occur in patients with adequate volume status.5. Hypoventilation - A potentially lethal complication of mask CPAP is hypoventilation, which may occur with excessive levels of CPAP. Overdistension of normal lung units can increase the ratio of dead space to tidal volume and result in CO2 retention. Hypoventilation may also occur in patients who become lethargic and weak. All patients receiving CPAP therapy should be closely monitored, and if CO2 retention is identified, intubation and mechanical ventilation should be instituted.6. Fluid Retention - The application of CPAP causes a reduction in urine output secondary to reduced renal perfusion, redistribution of renal blood flow and increased antidiuretic hormone secretion. It is often necessary to modify fluid therapy or employ diuretics when applying positive airway pressure if fluid retention and odema are to be avoided. Alternatively, the depression of cardiovascular and renal function which may occur with CPAP may be treated successfully with inotropic agents.
48CPAP Flow Sheet No Exclusion Criteria Present -Respiratory/Cardiac ArrestPt.unable to follow commandsUnable tp maintain patent airway independentlyMajor TraumaSuspicion of a PneumothoraxVomiting or Active GI BleedObvious signs/Symptoms of Pulmonary infection2 or more of the following Respiratory DistressInclusion CriteriaRetractions of accessory musclesBrochospasm or Rales on ExamRespiratory Rate > 25/min.O2 Sat. < 92% on high flow O2Administer CPAP using Max FIO2Stable or Improving Reassess Patient DeterioratingContinue CPAPContinue COPD/Asthma/Pulmonary Edema ProtocolContact Medical Control with a Report-Contact Medical Control with reportDiscontinue CPAP unless advised by Medical ControlContinue Asthma/COPD/Pulmonary Edema Protocols,
49Ventilatory Support: Intubation Definitive (but not first) treatment of pulmonary edemaPositive pressure redistributes edema fluid as in CPAP but to a greater extentMechanical ventilation greatly reduces O2 demandSedation/paralysis also reduces O2 demand and increases complianceCPAP: Continuous Positive Airway PressureThe term ‘continuous positive airway pressure’ was coined in 1971 by Gregory et al to describe an elevated airway pressure therapy for spontaneously breathing, intubated neonates.Current application has expanded to include adults and more recently patients without an artificial airway.‘The application of positive airway pressure throughout the whole respiratory cycle to spontaneously breathing patients’ (Keilty et al. 1992).
50Ultimate TherapiesIf pt stabilizes: long term therapy with beta blockers and ACE inhibitorsIf cardiac output remains unacceptable:Beta agonistsLVADTransplant
51In SummaryHeart failure is the result of an acute event (MI, AF) or chronic decompensationPulmonary edema frequently results from cardiac failure but may also result from other disease processes (ARDS) or direct insultCorrect diagnosis is crucial and depends on good history and examTherapy is both pharmacological and ventilatory support