Acute respiratory distress syndrome (ARDS)

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ACUTE RESPIRATORY DISTRESS SYNDROME

(ARDS)

Presented By:Atul Lawrence

Medical Surgical Nursing

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INTRODUCTION TO RESPIRATORY SYSTEM

Mr sanjay. M. Peerapur, Principal, KLES Institute of Nursing Sciences, Hubli

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INTRODUCTION TO RESPIRATORY SYSTEM contd…………


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INTRODUCTION TO RESPIRATORY SYSTEM contd…………


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RESPIRATORY DISTRESS SYNDROME (ARDS)• Acute respiratory distress syndrome (ARDS) is a life-threatening lung condition that prevents enough oxygen from getting into the blood.

• Acute respiratory distress syndrome was first described in 1967 by Ashbaugh and colleagues.

• ARDS is also referred with variety of terms like • Stiff Lung• Shock lung• Wet lung• Post traumatic lung• Adult respiratory distress syndrome• Adult hyaline membrane disease• Capillary leak syndrome & • Congestive atelectasis.


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DEFINITION

• Acute respiratory distress syndrome (ARDS) is a sudden and progressive form of acute respiratory failure in which the alveolar capillary membrane becomes damaged and more permeable to intravascular fluid resulting in severe dyspnea, hypoxemia and diffuse pulmonary infiltrates.


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ETIOLOGY & RISK FACTORS• Direct Lung Injury

– Common causes• Aspiration of gastric contents or other substances.• Viral/bacterial pneumonia

– Less Common causes• Chest trauma• Embolism: fat, air, amniotic fluid• Inhalation of toxic substances• Near-drowning• O2 toxicity• Radiation pneumonitis


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ETIOLOGY & RISK FACTORS contd…….• Indirect Lung Injury

– Common causes• Sepsis• Severe traumatic injury

– Less common causes• Acute pancreatitis• Anaphylaxis• Prolonged Cardiopulmonary bypass surgery• Disseminated intravascular coagulation• Multiple blood transfusions• Narcotic drug overdose (e.g., heroin)• Nonpulmonary systemic diseases• Severe head injury• Shock• Massive blood transfusion.


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SCHEMATIC REPRESENTATION OF PATHOPHYSIOLOGY OF ARDS

Lung injury

Release of Vasoactive substances (serotonin, histamine,

bradykinin)

Damaged alveolar cell

Surfactant production Alveolocapillary

membrane permeability

Vascular narrowing & obstruction

AlveolarCompliance and recoil

Bronchoconstriction

Outward migration of blood cells &

fluids from capillaries

Atelectasis

Pulmonary EdemaHyaline membrane

formation

Lung compliance

Impairment in gas exchange

ARDSPulmonary

hypertension

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CLINICAL MANIFESTATIONS• Early signs/symptoms

– Restlessness– Dyspnea– Low blood pressure– Confusion– Extreme tiredness– Change in patient’s behavior

• Mood swing• Disorientation• Change in LOC

– If pneumonia is causing ARDS then client may have• Cough • Fever

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CLINICAL MANIFESTATIONS CONTD…………

Late signs & symptoms– Severe difficulty in breathing i.e., labored, rapid

breathing.– Shortness of breath.– Tachycardia– Cyanosis (blue skin, lips and nails)– Think frothy sputum– Metabolic acidosis– Abnormal breath sounds, like crackles– PaCo2 with respiratory alkalosis.– PaO2

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DIAGNOSITC EVALUATION• History of above symptoms• On physical examination

– Auscultation reveals abnormal breath sounds• The first tests done are :

– Arterial blood gas analysis– Bood tests– Chest x-ray– Bronchoscopy– Sputum cultures and analysis

• Other tests are :– Chest CT Scan– Echocardiogram

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COMPLICATIONS• Common complications are;

– Nosocomial pneumonia: – Barotrauma– Renal failure

• Other complications are : – O2 toxicity, – stress ulcers, – Tracheal ulceration, – Blood clots leading to deep vein thrombosis &– pulmonary embolism.

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MEDICAL MANAGEMENT• Persons with ARDS are hospitalized and require

treatment in an intensive care unit. • No specific therapy for ARDS exists.• Supportive measures :

– Supplemental oxygen – Mechanical respirator – Positioning strategies

• Turn the patient from supine to prone. • Another position is lateral rotation therapy

• Fluid therapy

Intubation Procedure

Preoxygenate with 100% oxygen to provide apneic or distressed patient

with reserve while attempting to intubate.

Do not allow more than 30 seconds to any intubation attempt.

If intubation is unsuccessful, ventilate with 100% oxygen for 3-5 minutes

before a reattempt.


Insert Laryngoscope



After displacing the epiglottis insert the ETT.

The depth of the tube for a male patient on average is 21-23 cm at teeth

The depth of the tube on average for a female patient is 19-21 at teeth.


Confirm tube position:

By auscultation of the chestBilateral chest riseTube location at teethCO2 detector – (esophageal detection device)

Intubation Procedure Stabilize the ETT

Ventilator Settings Terminology

•A/C: Assist-Control•IMV: Intermittent Mandatory Ventilation•SIMV: Synchronized Intermittent Mandatory Ventilation•Bi-level/Biphasic: Non-inversed Pressure Ventilation with Pressure Support (consists of 2 levels of pressure)

Ventilator Settings Terminology (con’t)

•PRVC: Pressure Regulated Volume Control •PEEP: Positive End Expiratory Pressure•CPAP: Continuous Positive Airway Pressure•PSV: Pressure Support Ventilation•NIPPV: Non-Invasive Positive Pressure Ventilation

Basics of Mechanical Ventilation

Settings1. Trigger mode and sensitivity2. Respiratory rate 3. Tidal Volume4. Positive end-expiratory pressure (PEEP)5. Flow rate6. Inspiratory time7. Fraction of inspired oxygen

TriggerThere are two ways to initiate a ventilator-delivered

breath: pressure triggering or flow-by triggeringWhen pressure triggering is used, a ventilator-

delivered breath is initiated if the demand valve senses a negative airway pressure deflection (generated by the patient trying to initiate a breath) greater than the trigger sensitivity.

When flow-by triggering is used, a continuous flow of gas through the ventilator circuit is monitored. A ventilator-delivered breath is initiated when the return flow is less than the delivered flow, a consequence of the patient's effort to initiate a breath

Tidal VolumeThe tidal volume is the amount of air

delivered with each breath. The appropriate initial tidal volume depends on numerous factors, most notably the disease for which the patient requires mechanical ventilation.

Respiratory RateAn optimal method for setting the respiratory

rate has not been established. For most patients, an initial respiratory rate between 12 and 16 breaths per minute is reasonable

Positive End-Expiratory Pressure (PEEP)Applied PEEP is generally added to mitigate

end-expiratory alveolar collapse. A typical initial applied PEEP is 5 cmH2O. However, up to 20 cmH2O may be used in patients undergoing low tidal volume ventilation for acute respiratory distress syndrome (ARDS)

Flow RateThe peak flow rate is the maximum flow

delivered by the ventilator during inspiration. Peak flow rates of 60 L per minute may be sufficient, although higher rates are frequently necessary. An insufficient peak flow rate is characterized by dyspnea, spuriously low peak inspiratory pressures, and scalloping of the inspiratory pressure tracing

Inspiratory Time: Expiratory Time Relationship (I:E Ratio)During spontaneous breathing, the normal

I:E ratio is 1:2, indicating that for normal patients the exhalation time is about twice as long as inhalation time.

If exhalation time is too short “breath stacking” occurs resulting in an increase in end-expiratory pressure also called auto-PEEP.

Depending on the disease process, such as in ARDS, the I:E ratio can be changed to improve ventilation

Fraction of Inspired OxygenThe lowest possible fraction of inspired

oxygen (FiO2) necessary to meet oxygenation goals should be used. This will decrease the likelihood that adverse consequences of supplemental oxygen will develop, such as absorption atelectasis, accentuation of hypercapnia, airway injury, and parenchymal injury

MODES of VENTILATION

Control Mode

Delivers pre-set volumes at a pre-set rate and a pre-set flow rate.The patient CANNOT generate spontaneous breaths, volumes, or flow rates in this mode.

Assist/Control Mode

•Delivers pre-set volumes at a pre-set rate and a pre-set flow rate.•The patient CANNOT generate spontaneous volumes, or flow rates in this mode. •Each patient generated respiratory effort over and above the set rate are delivered at the set volume and flow rate.

Delivers a pre-set number of breaths at a set volume and flow rate.Allows the patient to generate spontaneous breaths, volumes, and flow rates between the set breaths.Detects a patient’s spontaneous breath attempt and doesn’t initiate a ventilatory breath – prevents breath stacking

SYCHRONIZED INTERMITTENT MANDATORY VENTILATION (SIMV):

SIMV cont.

Machine BreathsSpontaneous Breaths

PRESSURE REGULATED VOLUME CONTROL (PRVC):

• This is a volume targeted, pressure limited mode. (available in SIMV or AC)

• Each breath is delivered at a set volume with a variable flow rate and an absolute pressure limit.

• The vent delivers this pre-set volume at the LOWEST required peak pressure and adjust with each breath.

PRVC

POSITIVE END EXPIRATORY PRESSURE

(PEEP):

• This is NOT a specific mode, but is rather an adjunct to any of the vent modes.

• PEEP is the amount of pressure remaining in the lung at the END of the expiratory phase.

• Utilized to keep otherwise collapsing lung units open while hopefully also improving oxygenation.

PEEP cont.

PEEP is the amount of pressure remaining in the lung at the END of the expiratory phase.

Pressure above zero

Continuous Positive Airway Pressure (CPAP):

• This IS a mode and simply means that a pre-set pressure is present in the circuit and lungs throughout both the inspiratory and expiratory phases of the breath.

• CPAP serves to keep alveoli from collapsing, resulting in better oxygenation and less WOB.

• The CPAP mode is very commonly used as a mode to evaluate the patients readiness for extubation.

HIGH FREQUENCY VENTILATION

Oxygenation

• Oxygenation is primarily controlled by the Mean Airway Pressure (Paw) and the FiO2.

• Mean Airway Pressure is a constant pressure used to inflate the lung and hold the alveoli open.

• Since the Paw is constant, it reduces the injury that results from cycling the lung open for each breath

Initial Settings

• Select your mode of ventilation• Set sensitivity at Flow trigger mode• Set Tidal Volume• Set Rate• Set Inspiratory Flow (if necessary)• Set PEEP• Set Pressure Limit• Humidification

Post Initial Settings

• Obtain an ABG (arterial blood gas) about 30 minutes after you set your patient up on the ventilator.

• An ABG will give you information about any changes that may need to be made to keep the patient’s oxygenation and ventilation status within a physiological range.

ABG

• Goal:• Keep patient’s acid/base balance within

normal range:

• pH 7.35 – 7.45• PCO2 35-45 mmHg• PO2 80-100 mmHg

TROUBLESHOOTING

TROUBLESHOOTING

• Anxious Patient

– Can be due to a malfunction of the ventilator– Patient may need to be suctioned– Frequently the patient needs medication for anxiety

or sedation to help them relax

• Attempt to fix the problem • Call your RT

Low Pressure Alarm

• Usually due to a leak in the circuit.

– Attempt to quickly find the problem– Bag the patient and call your RT.

High Pressure Alarm

• Usually caused by:– A blockage in the circuit (water

condensation)– Patient biting his ETT– Mucus plug in the ETT

– You can attempt to quickly fix the problem

– Bag the patient and call for your RT.

Low Minute Volume Alarm

• Usually caused by:– Apnea of your patient (CPAP)– Disconnection of the patient from

the ventilator

– You can attempt to quickly fix the problem

– Bag the patient and call for your RT.

Accidental Extubation• Role of the Nurse:

– Ensure the Ambu bag is attached to the oxygen flowmeter and it is on!

– Attach the face mask to the Ambu bag and after ensuring a good seal on the patient’s face; supply the patient with ventilation.

–Bag the patient and call for your RT.

OTHER

• Anytime you have concerns, alarms, ventilator changes or any other problem with your ventilated patient.

–Call for your RT–NEVER hit the silence

button!

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TURNING PATIENT PRONE ON VOLLMAN PRONE POSITIONER

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PATIENT LYING PRONE ON VOLLMAN PRONE POSITIONER

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LATERAL ROTATION THERAPY BED

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MEDICAL MANAGEMENT contd…….• Medications :

– Antibiotics– Anti-inflammatory drugs; such as corticosteroids– Diuretics– Drugs to raise blood pressure– Anti-anxiety– Muscle relaxers– Inhaled drugs (Bronchodilators)

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NURSING DIAGNOSIS 1. Ineffective breathing pattern related to decreased lung

compliance, decreased energy as characterized by dyspnea, abnormal ABGs, cyanoisis & use of accessory muscles.

2. Impaired gas exchange related to diffusion defect as characterized by hypoxia (restlessness, irritability & fear of suffocation), hypercapnia, tachycardia & cyanosis.

3. Risk for decreased Cardiac output related to positive pressure ventilation

4. Ineffective protection related to positive pressure ventilation, decreased pulmonary compliance & increased secretions as characterized by crepitus, altered chest excursion, abnormal ABGs & restlessness.

NURSING DIAGNOSIS CONTD……..

5. Impaired physical mobility related to monitoring devices, mechanical ventilation & medications as characterized by imposed restrictions of movement, decreased muscle strength & limited range of motion.

6. Risk for impaired skin integrity related to prolonged bed rest, prolonged intubation & immobility.

7. Knowledge deficit related to health condition, new equipment & hospitalization as characterized by increased frequency of questions posed by patient and significant others.

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Education

Acute respiratory distress syndrome (ARDS)