Neural basis of dyspnea

 

Subpulmonic effusion

 Pleural effusion that remains in the infrapulmonary location without spilling into the costophrenic sulci or extending up the chest wall. 

 Characteristics in CXR:

a) apparent elevation of one or both diaphragms 

b) Apex of the diaphragm is more lateral than usual 

c) Apparent diaphragm slopes much more sharply towards lateral costophrenic angle 

d) if subpulmonic effusion is on left side- lower border of lung is separated farther at its junction with infrapulmonary effusion 

e) lower lobe vessels may not be seen

Bronchial breath sounds

Bronchial breath sounds 

1. Character - harsh and loud, may be high pitched ( consolidation) or low pitched 

2. Expiration - all of expiration heard 

3. Gap - clear pause between inspiratory sound  and expiratory sound

Dyspnea scales

1. MMRC SCALE, 2.TRANSITION DYSPNEA INDEX(TDI), 3.VISUAL ANALOGUE SCALE, 4. BORG SCALE, 5. Baseline Dyspnea Index

Radiological signs of atelectasis

 Radiological signs of atelectasis

Direct signs 

1. Displacement of interlobar fissures 

2. Crowding of vessels and bronchi 

Indirect signs 

1. Local increase in opacity 

2. Elevation of hemidiaphragm 

3. Displacement of mediastinum 

4. Compensatory overinflation 

5. Displacement of hila 

6. Approximation of ribs 

7. Absence of air bronchogram 

8. Absence of visiblity of the interlobar artery

Types of Collapse

 Four types of atelectasis

1. Resorption atelectasis 

2. Relaxation atelectasis 

3. Adhesive atelectasis 

4. Cicatrization atelectasis

Fever definition

 Fever is an elevation of body temperature that exceeds normal daily variation and occurs in conjunction with an increase in hypothalamic set point. 

Temperature(oral) > 37.2 or > 98.9 at AM or 

                                >37.7 or > 99.9 at PM 

Reg- Harrison

Impalpable Apical Impulse

 Apical Impulse :- outermost and lower most point of definite cardiac impulse in the precordium.

Impalpable Apical Impulse is seen in

-overweight

-hyperinflated lungs (eg: COPD)

-behind the rib.

-pericardial effusion

-dextrocardia.

Causes of atypical pneumonia

 Mycoplasma pneumoniae

Chlamydophila--C.psittaci,C.pneumoniae

Bacteria--legionella,F.tularensis,Y.pestis,B.anthracis

Fungi--histoplasma,blastomyces,coccidioides,pneumocystis

Aspiration pneumonitis

Viral-influenza, adenovirus,RSV,parainfluenza,metapneumovirus,varicella-zoster,measles,EBV,CMV,hantavirus

Rickettsia-q fever

Complications of pulmonary tuberculosis

 Local 

1.Haemoptysis 

2.Post-tuberculosis bronchiectasis

 3.Fungal ball [aspergilloma] 

4.Tuberculosis endobronchitis and tracheitis 

5.Spontaneous pneumothorax 

6.Scar carcinoma

 7.Disseminated calcification of the lungs 

8.Pulmonary function changes, obstructive airways disease

 9.Secondary pyogenic infections

 Systemic 

1.Secondary amyloidosis 

2.Chronic respiratory failure

 3.Chronic cor-pulmonale

Ellis s shaped curve

 The upper limit of dullness is at least a space higher in the axilla compared to the limits of dullness anteriorly and posteriorly. Because of the shape of upper border of dullness , this is called Ellis''S'' curve, a phenomenon, which can also be observed radiologically.This is a radiological illusion and occurs as a medial radiological density due to the presence of partially aerated lung between the anterior and posterior fluid layers whereas the laterally the density is higher due to the presence of fluid only

Neural tracts of dyspnea

 The sensation appears to have two primary peripheral sensors—chemoreceptors and vagal C fibers; the chemoreceptors probably include the aortic and carotid bodies and/or vagal C fibers. Additional afferent information is provided by chest wall mechanoreceptors and vagal stretch receptors. 

Afferent neural information is conveyed to the NTS in the medulla and from there, probably via the thalamus, to the insular cortex and limbic system, especially the anterior insula, and the sensorimotor cortex. 

Thus, it can be speculated that dyspnea occurs when there is an increase above usual levels of reflex afferent information from the peripheral sensors, which is processed in the insula and cortical network and generates a neural output to the respiratory system; afferent feedback on the effects of this neural output (pulmonary volume change, airflow, and ventilation), is provided by the pulmonary stretch and other receptors innervated by the vagal nerves and by chest wall mechanoreceptors. 

If central neural output does not produce the expected result (airflow or ventilation), either because of muscle paralysis or abnormal lung mechanics (eg, in COPD, asthma or restrictive lung disease), a sensation of dyspnea is generated. 

In asthma and COPD the relationship between inspiratory neural drive and ventilatory output, and therefore dyspnea, may worsen (increased functional residual capacity) on exercise and improves with bronchodilation.

 This assumes that the cortical centers have a pre-existing memory of “normal” afferent input and “normal” respiratory system response, in terms of effort required to achieve a given airflow or ventilation. 

The extent of the mismatch between the new afferent/efferent information and preexisting memory, (“a change in the relationship between central respiratory drive and output, ie, ventilation or effort”) determines the intensity of dyspnea.

Swelling

 HISTORY:

1.Duration

2.Mode of onset

3.Associated symptoms 

4.Pain

5.Progression

6.Exact site

7.Fever

8.Other lumps

9.Secondary changes

10.Impairment of function

11.Recurrence of swelling 

12.Loss of body weight

EXAMINATION:

I.INSPECTION:

1.Site

2.Colour 

3.Shape

4.Size

5.Surface

6.Edge

7.Number

8.Pulsation

9.Peristalsis 

10.Movement with respiration 

11.Impulse on Coughing

12.Movement on deglutition

13.Movement with protrusion of tongue

14.Skin over the swelling

15.Any pressure effect

B.PALPITATION:

1.Temperature 

2.Tenderness

3.Size,Shape,Extent

4.Surface

5.Edge

6.Consistency 

7.Fluctuation 

8.Fluid thrill

9.Translucency 

10.Impulse on coughing

11.Reducibility

12.Compressibility 

13.Pulsatility

14.Fixity to the overlying skin

15.Relation to surrounding structures 

C.STATE OF REGIONAL LYMPH NODES

D.PERCUSSION

F.AUSCULTATION 

G.MEASUREMENTS 

H.MOVEMENTS 

SOCRATES

S- Site

O- Onset

C- Character

R- Radiation 

A- Associated Symptoms 

T- Timing (Duration,Course,Pattern)

E- Exacerbating and Relieving Factors 

S- Severity

PULSUS PARADOXUS

- Definition:-

  Inspiratory decline in systolic pressure greater than 10mm of Hg.

- Measurement :-

 Step 1 : inflate blood pressure cuff until no sounds are heard.

Step 2  : slowly decrease the pressure until systolic sound are heard during expiration but not during inspiration. Note this pressure

Step 3 : decrease the pressure further until sounds are heard through out the respiratory cycle. Note this pressure.

Step 4 : if pressure difference between the two is greater than 10mm Hg, it is called as Pulsus Paradoxus.

- Seen in :-

Acute severe Asthma.

Cardiac tamponade.

Pericardial constriction.

- Mechanism :-

Normally, during inspiration, there is a decrease in intra thoracic pressure which results in increased venous return. This causes increased right ventricular filling and stroke volume, but the left ventricular stroke volume falls slightly.

But in Cardiac tamponade and pericardial constriction, the increased inspiratory right ventricular stroke volume reduces the left ventricular compliance, resulting in pronounced fall in systolic pressure during the inspiration.   

In case of acute severe asthma, the negative pleural pressure increasing the afterload and thereby impedance to left ventricular filling.

BODY MASS INDEX (BMI)

                                                BODY MASS INDEX.

It is a simple index of weight for height that is commonly used to classify underweight, over weight and obesity in adults.

It is defined as weight in Kgs divided by square of the height in meters.(kg/m^2).

It is age and sex independent.

WHO classification :

BMI :- 

<18.5 = underweight.

18.5 - 24.9 = normal range.

25 - 29.99 = pre obese.

30 - 34.99 = obese class I.

35 - 39.99 = obese class II.

>= 40 = obese class III.

Drawback :-

BMI does not distinguish between weight associated with muscle and weight associated with fat.

So, increased BMI need not imply increased fat content in the body. 

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