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باطنية

د. ظاهر

عدد الاوراق (3)

2/10/2012

Acute dyspnea

Dyspnea

Dyspnea is subjective experience of breathing discomfort that consists of qualitatively distinct sensations that vary in intensity . Dyspnea , a symptom , must be distinguished from signs of increased work of breathing

Mechanism of Dyspnea

Respiratory sensations are the consequence of interactions between the efferent , motor output from the brain to the ventilatory muscles and afferent, sensory input from receptors throughout the body and integrative processing of this information that we infer must be occurring in the brain.

Motor efferents

Disorders of ventilatory pump ;
increased work of breathing When muscles are weak/fatigued , greater effort is required even though other mechanics of system are normal.


Sensory afferents
Sensory Afferents Chemoreceptors in carotid bodies & medulla activated by hypoxemia, acute hypercapnia and acidemia
Mechanoreceptors in lungs stimulated by bronchospasm chest tightness
J-receptors sensitive to interstitial edema Pulmonary vascular receptors activated by acute changes in Pul.A pressure air hunger. Metaboreceptors skeletal muscle - exercise

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Physiological basis
Physiological basis Increased ventilatory drive
1. increase PaCo2COPD
2. decreasePaO2asthma,COPD, acidemia diabetic ketoacidosis , lactic acidosis
3. fever
4. exercise.
Physiological basis Reduced ventilatory capacity
1. decrease lung vol restrictive lung ds (pneumonia,pul.edema,ILD)
2. Pleural pain
3. Increase resistance to airflow asthma, COPD, upper airway &laryngeal obstruction.

Dyspnea

Intemittent dyspnea reversible process (CHF, asthma, pul. embolism)
Nocturnal dyspnea CHF,GERD, asthma.
Orthopnea (recumbent position) CHF, ascites, pregnancy, obst. lung ds, resp.muscle weakness
Platypnea (upright position)- AVmalformations at lung bases, interatrial shunts, cirrhosis
Dyspnea on exertion cardiac/pulmonary


Dyspnea independent of activity mech (aspiration), allergic , psychological.
Trepopnea -(dyspnea in one lateral position but not the other) pleural effusion , obst of prox tracheobronchial tree .
Paroxysmal nocturnal dyspnea dyspnea, cough, frothy sputum streaked with blood, sweating, pallor , tachycardia , crackles IHD, Aortic valve ds, AF, HTN, Cardiomyopathy

Classification of dyspnea

Class 1 No limitations.Ordinary physical activity does not cause dyspnea
Class 2 Slight limitation of physical activity. Class 3 Marked limitation of physical activity.
Class 4 dyspnea at rest

Physical examination

Respiratory Rate
Body habitus cachexia / obesity
Posture leaning forward on elbows with COPD, supine in bed
Use of Accessory muscles, Pursed lips Lower extremity edema b/L CHF & u/L thromboembolism .
Clubbing malignancy .
chest expansion
Physical Examination
Crackles, wheeze ( localised / diffuse ) Decreased breath sounds pneumothorax , pleural effusion
RV heave , increased P2 pul.hypertension
Elevated JVP , hepatojugular reflux, pedal edema RV Failure
Diffuse,lateral displaced pt of max impulse, S3 gallop ,crackles , elevated JVP LV Failure


Classification of dysponea by its clinical presentation
A.Dyspnoea of Rapid Onset
B.Dyspnoea Progressing Over A Few Months
C.Dyspnoea Which is Slowly Progressing

Causes of acute severe dyspnea

Acute Severe Dyspnea Cardiac : Pul.edema from myocardial dysfn,including ischemia & valvular dysfn.
Pulmonary : Acute severe asthma, Acute exacerbation of COPD, Pneumothorax, Pneumonia, Pul.embolism, ARDS, Inhaled Foreign body , Laryngeal edema, Lobar Collapse, Pul.Hage, Aspiration, Bronchiolitis obliterans , inhaled toxins Others :
Metabolic acidosis , Psychogenic Hyperventilation

Classification of dysponea by its clinical presentation

A.Dyspnoea of Rapid Onset

1.Pulmonary

a.pneumonia
b.pneumothorax
c.Asthma
d.Inhaled foreign body

2.Cardiovascular

a.left heart failure
b.pulmonary embolism
c.pericardial tamponiade
d.high altitude


3.Psychogenic

4.Metabolic

a.diabetic ketoacidosis
b.uraemia
c.poisons

Dyspnoea Progressing Over A Few Months

1.Pulmonary
a.pleural effusion
b.tumour(including lymphangitis carcinomatosis)
c.pulmonary infilteration and fibrosis
d.tuberculosis

2. Cardiovascular

a. congestive cardiac failure
b.anaemia
c.recurrent pulmonary embolism

3-Neuromuscular

Myasthenia gravis
Investigation of patient with dyspnea


Chest x-ray
Spirometry
Blood gass

Investigation for acute severe dyspnea

ABC establish airway and ensure oxygenation
CXR PA
View Arterial Blood Gases measurements
ECG ,V/Q Scan
Echocardiogram .
Spirometry HRCT CT pulmonary angiography

Investigation of patient with dyspnea

Chest x-ray
a.It may show cardiomegaly
b.pulmonary infilteration
c.pleural effusion
d.tumours
e.collaps or consolidation


Spirometry
reduced FVC in restrictive lung disease
E.g pleural effusion,pulmonary fibrosis.
Muscle weakness like myasthenia gravis

Blood gass

Pulse Oximetry is not sufficient : Pt with N oxygenation , metabolic / resp acidosis can be dyspneic, -- need to exhale Co2 to raise pH.
In Methemoglobinemia, the apparent O2 saturation is high, but actual PO2 is low.
Pulmonary embolism ( low PO2 and normal to low Pco2).

Causes of chronic dyspnea

Causes of Chronic Dyspnea Altered central ventilatory drive: central sleep apnea, obesity hypoventilation syn, idiopathic hyperventilation Metabolic: Increased metabolic needs (hyperthyroidism, obesity), Metabolic Acidosis (renal failure) Physiological : high altitude, vigorous exercise, pregnancy.










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