Chap 23 Acute Respiratory Distress Syndrome

Acute Respiratory Distress Syndrome

Form of hypoxemic respiratory failure

Associated pulmonary edema leads to:

• Severe hypoxemia

• Intrapulmonary shunting

• Reduced lung compliance

• In some cases, irreversible damage to lung tissue

Management of Acute Respiratory Distress Syndrome

• Replace fluids. 

• Provide drug therapy to support mechanical ventilation.

• Administer pharmacologic agents to stabilize pulmonary, capillary, and alveolar walls.

• Provide diuretics.

• Consider cause of the underlying problem. 

• Provide high-flow nasal oxygen and ventilator support. 

Pulmonary Embolism

Blockage of a pulmonary artery by a clot or other foreign material

• Usually originates in lower extremities or pelvis 

• Relatively common

• Sudden death is the first sign in about one-fourth of patients. 

Virchow triad

factors contribute to clot formation

• Hypercoagulability

• Stasis

• Vessel injury

Signs and symptoms of Pulmonary Embolism

• Dyspnea, cough

• Hemoptysis (rare)

• Pain

• Anxiety 

• Syncope

• Hypotension

• Diaphoresis

• Tachypnea

• Sinus tachycardia

• Fever

• Distended neck veins

• Chest splinting, pleuritic pain, pleural friction rub, crackles, and localized wheezing

Management of Pulmonary Embolism

Prehospital care is mainly supportive. 

• Administer supplemental high-concentration oxygen.

• Apply cardiac monitor and pulse oximeter.

• Establish IV line.

• Transport in position of comfort. 

Upper Respiratory Tract Infection

• Common and rarely life-threatening

• Can affect nose, throat, sinuses, and larynx

• Includes common cold, pharyngitis, tonsillitis, sinusitis, and laryngitis

• May exacerbate underlying pulmonary conditions

Signs and symptoms of Upper Respiratory Tract Infection

• Sore throat

• Fever

• Chills

• Headache

• Facial pain (sinusitis)

• Purulent nasal drainage

• Halitosis (bad breath)

• Cervical adenopathy

• Erythematous pharynx 

Spontaneous Pneumothorax

Usually results when bleb ruptures, allowing air to enter pleural space

• May occur in seemingly healthy people aged 20–40 years

• Secondary spontaneous pneumothorax may develop from underlying disease.

Common signs and symptoms of Spontaneous Pneumothorax

• Shortness of breath

• Sudden onset of chest pain

• Pallor

• Diaphoresis

• Tachypnea

severe cases:

• Altered mental status

• Cyanosis

• Tachycardia

• Decreased breath sounds on affected side

• Local hyperresonance to percussion

• Subcutaneous edema

Management of Spontaneous Pneumothorax

Prehospital care is based on patient’s symptoms and degree of respiratory distress:

• High-concentration oxygen

• Airway, ventilator, and circulatory support

• Transport in position of comfort.

• If tension pneumothorax develops, perform needle chest decompression.

Hyperventilation Syndrome

Abnormally deep or rapid breathing that results in excessive loss of carbon dioxide

• Produces hypocapnia

• Leads to:

  • Cerebrovascular constriction

  • Reduced cerebral perfusion

  • Paresthesia

  • Dizziness

  • Feelings of euphoria

Conditions that can cause hyperventilation syndrome

• Anxiety

• Hypoxia

• Pulmonary disease

• Cardiovascular disorders

• Metabolic disorders

• Neurologic disorders

• Fever

• Infection

• Pain 

• Pregnancy

• Drug use

Signs and symptoms of Hyperventilation Syndrome

• Dyspnea with rapid breathing and high minute volume

• Chest pain

• Facial tingling

• Carpopedal spasm

Management of Hyperventilation Syndrome

• Provide supportive care if life threats have been ruled out.

• Administer oxygen administration.

• Provide airway/ventilator support.

• Calm patient and coach ventilations.

• Do not attempt to slow ventilations if patient is compensating for hypoxia or metabolic acidosis. 

• If severe or complicated, transport for evaluation by physician. 

Lung Cancer

Most cases develop in people age 65 years or older.

Of new cases reported, most patients die within 1 year.

Most common cause is cigarette smoking.

• Other risk factors include:

  • Passive smoking 

  • Exposure to asbestos, radon gas, dust, or coal products

  • Radiation therapy

  • Pulmonary fibrosis

  • Human immunodeficiency virus infection

  • Genetic factors

  • Alcohol consumption and exposure to other toxins

Pathophysiology of Lung cancer

Lung cancer—uncontrolled growth of abnormal cells

• At least a dozen different cell types of tumors are associated with primary lung cancer. 

• Two major cell types: small cell and non-small cell

• Most abnormal cell growth begins in bronchi or bronchioles.

Signs and symptoms of Lung cancer

• Cough

• Hemoptysis

• Dyspnea

• Hoarseness or voice change

• Dysphagia

• Weight loss/anorexia

• Weakness

• Chest pain

Management of Lung cancer

• Provide airway, ventilator, and circulatory support.

• Administer oxygen if indicated.

• Transport for evaluation by physician.

• Administer IV fluids if needed.

• Provide drug therapy and analgesics if needed.

• End-stage patients may have advance directives or DNR orders.

Respiratory Failure

Respiratory emergencies can result from many disease states, including:

• Ventilatory failure

• Oxygenation failure

• Shock

Occurs when pulmonary gas exchange is sufficiently impaired to cause hypoxemia with or without hypercapnia

Hypoxemia

(oxygenation failure)

Conventional criteria:

PaO2 <60mm Hg

Causes:

• Perfusion defect

• Pneumonia

• Pulmonary edema

• Pulmonary embolism

• Pulmonary contusion

•  Sepsis

• V/Q mismatch

Hypercapnia

(Ventilatory failure)

Conventional criteria:

PaC02 >55mm Hg

Causes:

• Asthma

• Bronchiectasis

• CNS injury

• COPD

• Drug overdose

• Fatigue

• Pump failure

Physiology Review

Exchange of gases between cells and environment

Ventilation—brings oxygen to lungs and removes carbon dioxide, which enables external or internal respiration

Other essential elements

• Structure and function of chest wall

• Control of breathing by central nervous system

• Acid–base balance mediated by buffer systems

Risk Factors Associated With the Development of Respiratory Disease - Intrinsic Factors

Genetic predisposition may influence the development of these conditions:

• Asthma

• Obstructive lung disease

• Cancer

• Cardiac or circulatory disorders may influence the de-velopment of these conditions:

• Pulmonary edema

• Pulmonary emboli

Risk Factors Associated With the Development of Respiratory Disease - Extrinsic Factors

Smoking increases the following:

• Prevalence of chronic obstructive pulmonary disease (COPD) and cancer

• Severity of virtually all respiratory disorders

• Indoor and outdoor environmental pollutants increase the following:

• Prevalence of COPD

• Severity of all obstructive airway disorders

Ventilation

Air movement into and out of lungs

To occur, following must be intact:

• Neurologic control

• Nerves between brainstem and respiration muscles

• Functional diaphragm and intercostal muscles

• Patent upper airway

• Functional lower airway

• Alveoli functional and not collapsed

Emergency treatments: ensuring upper and lower airways are open and clear and providing assisted ventilation

Diffusion

Movement of a substance from area with a higher concentration of particles to area with a lower concentration

• Results in an even distribution of particles within the medium 

• Occurs between air-filled alveoli and pulmonary capillary bed

• The following must be intact:

  • Alveolar and capillary walls that are not thickened or damaged

  • Interstitial space between alveoli and capillary wall that is not enlarged or filled with fluid

Emergency treatment

• Providing high-concentration oxygen

• Reducing inflammation in interstitial space

• Identify underlying cause

Perfusion

Circulation of blood through lung tissues

The following must be intact:

• Adequate blood volume

• Adequate hemoglobin in the blood

• Pulmonary capillaries that are not occluded

• Efficient pumping by the heart, providing a smooth flow of blood through the pulmonary capillary bed

To treat perfusion problems:

• Ensure circulating blood volume and hemoglobin levels are adequate

Respiratory Failure

Syndrome in which respiratory system fails in one or both of its gas-exchange functions

• Key signs of impending respiratory failure 

  • Decreasing SaO₂ level despite oxygen therapy

  • Increasing ETCO₂ level

  • Evidence of fatigue

  • Decreasing consciousness

  • Nasal flaring

  • Seesaw ventilation

  • Arrhythmias

  • Cyanosis

Primary assessment

Focus is to detect and manage life-threatening conditions

Signs of life-threatening respiratory distress

• Alterations in mental status

• Severe cyanosis

• Stridor

• Inability to speak one or two words without dyspnea

• Tachycardia

• Pallor and diaphoresis

• Retractions/use of accessory muscles to assist breathing

Note any abnormal breath sounds and patient position.

Focused history

• Ascertain chief complaint

• Obtain focused history using OPQRST

• Obtain medication history

Secondary assessment

Guided by paramedic’s general impression of patient and patient’s chief complaint

• Note patient’s:

  • Position

  • Mental status

  • Ability to speak

  • Respiratory effort

  • Skin color

• Obtain vital signs:

  • Pulse rate

  • Blood pressure

  • Respiratory rate

• Assess patient’s face and neck for:

  • Pursed-lip breathing

  • Grunting

  • Nasal flaring

  • Use of accessory muscles

Inspect chest for injury or indicators of chronic disease. 

• Examine extremities for:

  • Peripheral cyanosis

  • Pitting edema

  • Clubbing of the fingers

  • Asterixis

  • Carpopedal spasm

Diagnostic Testing: Capnography

Noninvasive monitoring technique used in the prehospital setting 

• Provides information regarding: 

  • Ventilatory status

  • Effect of interventions

  • Correct tracheal tube placement

Numeric and graphical representation of carbon dioxide concentration exhaled through breath

Capnography

Diagnostic Testing: Peak Flowmeters

Measure a patient’s peak expiratory flow rate (PEFR)

Used most often to help determine severity of an asthma attack

Require cooperative patient

Obstructive Airway Disease 

Triad of diseases that often coexist: bronchitis and emphysema (COPD), and chronic obstructive asthma

• Major health problem affecting nearly 41 million people in US

• Predisposing factors: smoking, environmental pollution, industrial exposures, and various pulmonary infectious processes

Chronic Bronchitis

Characterized by an increase in number and size of mucus-producing glands

• Low PO₂ level

• Frequent respiratory tract infections

• Irreversible changes in the lung may result in:

  • Emphysema

  • Bronchiectasis

Emphysema

Results from pathologic changes in lungs

Characterized by:

• Permanent abnormal enlargement of air spaces beyond terminal bronchioles

• Destruction and collapse of alveoli

Over time, chest becomes barrel-shaped from air trapping. 

Full deflation of lungs becomes more difficult; eventually, it becomes impossible.

Assessment & Management of COPD

Patient usually has one or more of:

• Acute episode of worsening dyspnea manifested even at rest

• Increase or change in sputum production

• Increase in malaise that accompanies disease

• Other physical findings include wheezes, rhonchi, and crackles.

Management

• Administer oxygen, NIPPV, and drug therapy. 

• Obtain a thorough medical history.

• Establish IV line. 

• Apply cardiac monitor.

• Medications

  • Beta agonists

  • Nebulized anticholinergic

  • Steroids

Asthma

Reactive airway disease

• Most common chronic disease of childhood

Exacerbating factors tend to be extrinsic in children and intrinsic in adults.

• Childhood asthma often improves or resolves with age.

• Adult asthma usually is persistent.

Pathophysiology of Asthma

Occurs in acute episodes of variable duration

Creates excessive demand on muscles of respiration

• Leads to greater use of accessory muscles and respiratory fatigue

Complications: 

• Pulmonary edema

• Lobar atelectasis 

• Pneumonia

• Tension pneumothorax

Assessment of Asthma

• Patient usually in obvious respiratory distress

• Note mental status.

• Obtain initial history, including any previous intubations.

• Prolonged expiratory phase may be noted on auscultation.

• Wheezing is usually heard.

• Capnography waveform often has shark-fin appearance. 

Management of Asthma

• Oxygen therapy

• Drug therapy

  • Nebulized albuterol

  • Corticosteroids

• Nebulized magnesium sulfate

• NIPPV

• IV fluids for rehydration

• Transport in position of comfort

• Advanced airway management if indicated

Status asthmaticus

Severe, prolonged asthma attack not stopped with repeated doses of bronchodilators; true emergency

• Treatment is same as for acute attacks, but more urgent.

  • Provide IV fluids.

  • Administer high-concentration oxygen.

  • Anticipate need for intubation and aggressive ventilator support.

Pneumonia

Group of specific infections that cause acute inflammatory process of respiratory bronchioles and alveoli

• Caused by bacterial, viral, or fungal infection

• Typical signs and symptoms: 

  • Productive cough

  • Pleuritic chest pain

  • Tachypnea

  • Adventitious breath sounds

  • Fever that produces “shaking chills”

Management

• Provide airway support.

• Administer oxygen.

• Provide ventilatory assistance as needed.

• Administer IV fluids to support blood pressure and to thin and loosen mucus.

• Obtain cardiac monitoring.

• Transport for evaluation by a physician.

Viral pneumonia

• Influenza is the most common cause.

• In infants and young children, respiratory syncytial virus is the most frequent cause.

Signs and symptoms include: 

• Chest pain

• Cough

• Fever

• Dyspnea

• Occasionally hemoptysis

• General malaise 

• Auscultation of the chest may reveal: 

  • Wheezing 

  • Fine crackles

• Symptoms usually resolve in 7 to 10 days.

Bacterial pneumonia

Pneumococcus bacillus (Streptococcus pneumoniae) is the most common cause.

• Instances have declined due to vaccine.

• Mycoplasmal pneumonia

  • Causes mild upper respiratory tract infection in school-age children and young adults

  • Transmitted by infected respiratory secretions

Signs and symptoms include:

• Hypoxemia

• Acute shaking chills, fever

• Tachypnea, tachycardia

• Cough

• Sputum production (my be rust colored or yellow, green, or gray) 

• Anorexia, malaise, flank or back pain, and vomiting

• Symptoms usually resolve in 3 to 5 days.

Fungal pneumonia

Caused by environmental fungi 

• Accounts for small percentage of community-acquired cases

• Most common in those with chronic illness or weakened immune systems

• Treated with antifungal drugs

Aspiration pneumonia

An inflammation of lung tissue

• Results when foreign material enters tracheobronchial tree

Common in the following patients: 

• Patients with an altered level of consciousness

• Patients who are intubated

• Patients who have aspirated foreign bodies

May be nonbacterial

• Typically called pneumonitis 

Poor prognosis

Signs and symptoms vary with scenario and severity of insult: 

• Dyspnea, cough, bronchospasm

• Wheezes, rhonchi, crackles

• Cyanosis

• Pulmonary and cardiac insufficiency