college magazine: : Status Asthmaticus, Respiratory Obstruction (Asphyxia) and Pulmonary Oedema

· Note: Investigations are available in equipped hospitals and therefore patients may be referred after receiving pre-referral management. In hospitals, the investigations that can be done are outlined below

· Pulse oximetry values should be used to monitor the progression of asthma

· Obtain a complete blood count (CBC) and differential count

· Obtain an arterial blood gas

· Obtain a chest radiograph to evaluate for

Pneumonia
Pneumothorax
Congestive heart failure
Signs of chronic obstructive pulmonary disease

· These conditions may complicate patient's response to treatment

Treatment of Status Asthmaticus

· Patients with status asthmaticus need close monitoring as well as oxygen therapy and therefore referring them to hospitals with equipments is important.

· After confirming the diagnosis and assessing the severity of the asthma attack, direct treatment is toward controlling bronchoconstriction and further inflammation.

· Bronchodilator treatment with Beta-2 Agonists

o The first line of therapy is bronchodilator treatment with a beta-2 agonist is albuterol (Salbutamol).

o Handheld nebulizer treatments may be administered either continuously (10-15 mg/h) or by frequent timing (e.g. q5-20min), depending on the severity of the bronchospasm.

· Oxygen therapy

· Glucocorticosteroids

o Steroids are the most important treatment for status asthmaticus

· Fluid replacement

o Intravenous fluids are administered to restore blood volume, however should make sure the patients are not in congestive heart failure

· Antibiotics

o The routine administration of antibiotics is discouraged

o Patients are administered antibiotics only when they show evidence of infection such as pneumonia, sinusitis

· Aminophylline (theophylline)

Starting intravenous aminophylline may be reasonable in patients who do not respond to medical treatment with bronchodilators, oxygen, corticosteroids, and intravenous fluids within 24 hours
The loading dose is usually 5-6 mg/kg followed by a continuous infusion of 0.5-0.9 mg/kg/h
Aminophylline has some significant side effects and need to monitor for therapeutic range

Complications

· Pneumothorax may complicate acute asthma either because of increased airway pressure or as a result of mechanical ventilation.

· Superimposed infection can also occur in intubated patients.

· Patients may require a chest tube for pneumothorax or aggressive antibiotic therapy for a superimposed infection.

Epidemiology, Causes, Pathophysiology and Clinical Features of Respiratory Obstruction

Background

· Foreign body aspiration can be a life-threatening emergency

· An aspirated solid or semisolid object may lodge in the larynx or trachea

· If the object is large enough to cause nearly complete obstruction of the airway, asphyxia may rapidly cause death.

· Lesser degrees of obstruction or passage of the obstructive object beyond the carina can result in less severe signs and symptoms.

· Chronic debilitating symptoms with recurrent infections might occur with delayed extraction or the patient may remain asymptomatic.

· The actual aspiration event can usually be identified although it is often not immediately appreciated.

· The aspirated object might even escape detection.

· Most often the aspirated object is food but a broad spectrum of aspirated items has been documented over the years.

· Commonly retrieved objects include:

o Seeds

o Nuts

o Bone fragments

o Nails

o Small toys

o Coins, pins

o Medical instrument fragments and

o Dental appliances

· Geographic differences in the spectrum of objects commonly found in a particular environment and variations in dietary and eating habits affect the relative frequency with which various objects are aspirated.

Pathophysiology

· Near-total obstruction of the larynx or trachea can cause immediate asphyxia and death.

· Should the object pass beyond the carina, its location would depend on the patient's age and physical position at the time of the aspiration.

· Because the angles made by the main stem bronchi with the trachea are identical until age of 15 years, foreign bodies are found on either side with equal frequency in persons in this age group.

· With normal growth and development, the adult right and left main stem bronchi diverge from the trachea with very different angles, with the right main stem bronchus being more acute and therefore making a relatively straight path from larynx to bronchus.

· Objects that descend beyond the trachea are more often found in the right endobronchial tree than in the left.

· Cough, wheeze, stridor, dyspnea, cyanosis, and even asphyxia might ensue.

· Organic foreign bodies such as oily nuts (commonly peanuts) induce inflammation and Oedema.

· Local inflammation, Oedema, cellular infiltration, ulceration, and granulation tissue formation may contribute to airway obstruction while making bronchoscopic identification and removal of the object more difficult.

· The airway becomes more likely to bleed with manipulation and the object becomes more likely obscured and more difficult to dislodge.

· Mediastinitis or tracheoesophageal fistulas may result.

· Distal to the obstruction air trapping may occurs leading to local

o Emphysema

o Atelectasis

o Hypoxic vasoconstriction

o Post obstructive pneumonia and the

o Possibility of volume loss

o Necrotizing pneumonia or abscess

o Suppurative pneumonia, or bronchiectasis

· Bronchoscopically, the object may appear as a tumor.

· Even if the object is removed, the inflammatory changes may not be completely reversible.

· Some investigators believe scar carcinoma may develop over time.

· The likelihood of complications increases after 24-48 hours making expeditious removal of the foreign body imperative.

· Speaking while eating increases the likelihood of food aspiration.

· Impaired consciousness also increases the likelihood of aspiration while eating.

Causes

· Children are at risk for putting small toys, candies, or nuts into their mouths.

· Children aged 1-3 years chew incompletely with incisors before their molars erupt, and objects or fragments may be propelled posteriorly, triggering a reflex inhalation

· Among adults, the following conditions, actions, and procedures facilitate foreign body aspiration

Impaired swallowing reflex
Impaired cough reflex
Mental retardation
Alcohol or sedative use
General anesthesia
Poor dentition
Dental, pharyngeal, or airway procedures
Altered sensorium
Loss of consciousness
Convulsions
Maxillofacial trauma

· Frequently aspirated objects include food such as nuts and seeds, teeth, dental appliances and medical instruments.

· The original event might have been forgotten.

· Choking with severe dyspnea leading to respiratory or cardiac arrest while eating might be initially misdiagnosed as myocardial ischemia.

Epidemiology

· The often-fatal syndrome of acute asphyxia from upper airway obstruction associated with eating (acute asphyxia), and aspiration of gastric contents are usually not considered with other foreign body aspiration syndromes.

· For these reasons, the true incidence and prevalence of foreign body aspiration is unknown.

· The overall risk of death from acute asphyxia is estimated to be 0.66 deaths per 100,000 people.

· Morbidity increases if extraction of the object is delayed beyond 24 hours.

· The male-to-female ratio is 2:1.

· Children especially those aged 1-3 years are at risk for foreign body aspiration because of their tendency to put everything in their mouths and because of the way they chew.

· Young children chew their food incompletely with incisors before their molars erupt.

· Objects or fragments may be propelled posteriorly triggering a reflex inhalation.

· Adults are at increased risk of aspirating foreign bodies enduring oropharyngeal procedures as they are sedated.

Clinical Features

· History

In the acute asphyxia a large object (often poorly chewed meat) lodges in the larynx or trachea causing nearly complete airway obstruction.
Respiratory distress, aphonia, cyanosis, loss of consciousness, and death occur in quick succession unless the object is dislodged.
When the degree of obstruction is less severe or when the aspirated object descends beyond the carina, the presentation is less dramatic.
Sudden onset of the classic triad of coughing, wheezing and decreased breathing sounds is frequently not observed.
Presenting symptoms other than cough include

§ Fever (although this might be uncommon in early stage)

§ Hemoptysis

§ Dyspnea and

§ Chest pain

· A history of a choking episode is not always obtained or may have initially been ignored or misdiagnosed

· Most patients or parents can identify a specific episode of choking, however presentation is often delayed by more than a week.

· The latency period prior to the onset of symptoms may last months or years if the foreign body is inert bone or inorganic material.

· Patients may have been empirically treated for other conditions even when a choking episode was witnessed.

· Patients with chronic symptoms may have been erroneously diagnosed as having asthma or chronic bronchitis.

· Young children and patients with neurologic or psychiatric disorders are at increased risk for aspiration but might not be able to describe symptoms or to report choking episodes

· Other risk factors include

Institutionalization
Old age
Abnormal dentition
Alcohol or sedative use

· A presentation of cyanosis, cough, wheeze, incompletely resolved pneumonia, or localized bronchiectasis should raise suspicion of foreign body aspiration, particularly in individuals at risk for foreign body aspiration.

· Seek information about a history of

Impaired swallowing
Impaired coughing
Traumatic loss of consciousness
Intoxication or
Oropharyngeal surgery

Physical Findings

· A small number of foreign body aspirations are incidentally found after chest radiography or bronchoscopic inspection.

· Patients may be asymptomatic or may be undergoing testing for other diagnoses

· Physical findings may include

Stridor
Wheeze,
Diminished breath sounds

· If obstruction is severe cyanosis may occur

· Signs of consolidation can accompany post obstructive pneumonia

Differential Diagnosis, Investigations and Treatment of Respiratory Obstruction

Differential Diagnoses of Respiratory Obstruction

· Pneumonia

· Pneumothorax

· Lung Abscess

· Pulmonary Embolism

· Respiratory Failure

· Chronic Obstructive Pulmonary Disease (COPD)

· Emphysema

· Atelectasis

· Myocardial infarction

Investigations

· Investigations for respiratory obstruction cannot be done at primary health care facilities and therefore patients suspected of having the condition must be referred to hospitals. The investigations are listed here below.

o Chest radiography

o CT scanning of the chest

o Bronchoscope (both rigid and flexible) can be both diagnostic and therapeutic

o Fluoroscopy

o Radioisotope lung perfusion scanning

Treatment

Medical Care

· Acute choking, with respiratory failure associated with tracheal or laryngeal foreign body obstruction, may be successfully treated at the scene with the heimlich maneuver back blows and abdominal thrusts.

Heimlich Maneuver

· It is an emergency treatment for obstruction of the airway in adults.

· It may be needed when someone chokes on a piece of food that has ‘gone down the wrong way’.

· To perform the Heimlich maneuver.

o Stand behind the victim.

o Wrap your arms around their waist.

o Make a fist with one hand and hold the fist with the thumb side just below the breast bone.

o Place your other hand over this first and use it to pull sharply into the top of the choking person's abdomen and forcefully press up into the victim's diaphragm to expel the obstruction (most commonly food).

o Repeat as necessary.

o Children and infants need a different approach for the Heimlich maneuver

· Even in non emergency situations expeditious removal of tracheobronchial foreign bodies is recommended.

· Refer the patient after performing this emergency procedure for farther evaluation e.g.

Bronchoscopy
Surgical care

Prevention

· In order to prevent food aspiration the diet should be appropriate for the patient's ability to chew and swallow.

· The size and shape of food bits should be appropriate for the patient's age and the size of the larynx and tracheobronchial tree .

· Pay attention to the size and texture of foods and objects available to children and adults with impaired mentation or ability to protect the airway such as impaired chewing, swallowing or coughing.

· Removal of appliances prior to manipulation of the teeth or airway is essential.

· Note the condition of medical equipment at the beginning and end of procedures involving the pharynx, larynx, respiratory tract, or digestive tract.

· Sedatives and topical anesthetics increase the risk for aspiration therefore use them cautiously.

· Children should not be given toys or food substances that they can choke on.

Complications

· The severity of the complications of foreign body aspiration depends on the

o Size

o Shape

o Composition

o Location and

o Orientation of the aspirated object

· The following complications may ensue

o Cough

o Dyspnea

o Wheeze

o Stridor

o Hemoptysis

o Asphyxia

o Laryngeal oedema

o Pneumothorax

o Pneumomediastinum

o Tracheobronchial rupture

o Cardiac arrest

Classification and Clinical Features of Pulmonary Oedema

Introduction

· Pulmonary oedema refers to extravasation of fluid from the pulmonary vasculature into the interstitium and alveoli of the lung.

· The formation of pulmonary oedema may be caused by 4 major pathophysiologic mechanisms.

o Imbalance of starling forces which are

§ Increased pulmonary capillary pressure

§ Decreased plasma oncotic pressure

§ Increased negative interstitial pressure

o Damage to the alveolar-capillary barrier

o Lymphatic obstruction

o Idiopathic or unknown mechanism

Classification of Pulmonary Oedema

· Cardiogenic pulmonary oedema (CPE): This is defined as pulmonary oedema due to increased capillary hydrostatic pressure secondary to elevated pulmonary venous pressure.

· Non-Cardiogenic pulmonary oedema: This include several clinical conditions that are associated with pulmonary oedema based on an imbalance of starling forces other than through primary elevations of pulmonary capillary pressure.

Clinical Features of Pulmonary Oedema

Symptoms

· Breathlessness

· Anxiety

· Profuse diaphoresis

· Patients with symptoms of gradual onset CPE (e.g. over 24 h) often report dyspnea on exertion, orthopnea (respiratory discomfort when supine), and paroxysmal nocturnal dyspnea (patient awakens gasping for air and must sit up).

· Cough is a frequent complaint that may provide an early clue to worsening pulmonary oedema in patients with chronic left ventricle (LV) dysfunction.

· Pink frothy sputum may be present in patients with severe disease.

· Chest pain should alert the physician to the possibility of acute myocardial ischemia, infarction, or aortic dissection with acute aortic regurgitation as the precipitant of pulmonary oedema.

Physical Findings

· Tachypnea and tachycardia

· Patients may be sitting upright, they may demonstrate air hunger, and they may become agitated.

· Patients usually appear anxious and diaphoretic

· Hypertension is often present because of the hyper adrenergic state.

· Hypotension indicates severe LV systolic dysfunction and the possibility of cardiogenic shock.

· Auscultation of the lungs usually reveals fine crepitations, but rhonchi or wheezes may also be present.

· Rales (crepitations) are usually heard at the bases first; as the condition worsens, they progress to the apices.

· Auscultation of murmurs can help in the diagnosis of acute valvular disorders manifesting with pulmonary oedema.

· Another notable physical finding is skin pallor or mottling resulting from peripheral vasoconstriction and shunting of blood to the central circulation in patients with poor LV function and substantially increased sympathetic tone.

· Patients with concurrent right ventricular (RV) failure may present with hepatomegaly, positive hepatojugular reflux (seen in the neck region) and peripheral oedema.

· Severe cardio pulmonary oedema may be associated with a change in mental status which may be the result of hypoxia or hypercapnia (a condition where there is too much carbon dioxide in the blood).

Differential Diagnosis, Investigations and Treatment of Pulmonary Oedema

Differential Diagnosis

· Pneumonia

· Pneumothorax

· Pulmonary Embolism

· Respiratory Failure

· Diffuse pulmonary infections

· Aspiration

· Shock

· Acute Respiratory Distress Syndrome (ARDS)

· Asthma

· Cardiogenic Shock