PG Blazer » Pulmonology

Pneumonia – predisposing factors

pgblazer — Fri, 05 Aug 2011 04:39:54 +0000

Factors that predispose to development of pneumonia are: Smoking Alcohol Upper respiratory tract infections Recent influenza infection Corticosteroid therapy Old age Pre existing lung disease Related Articles ...

Air bronchogram – Mechanism, Causes

pgblazer — Thu, 20 Jan 2011 10:07:31 +0000

Air bronchogram refers to the visualisation of air filled bronchus when the surrounding alveoli are opacified

Causes:

Pulmonary consolidation
Pulmonary oedema
ARDS
Hyaline membrane disease
Alveolar cell carcinoma
Alveolar proteinosis
Sarcoidosis
Lymphoma

Mechanism:

Normally the lung fields are radioluscent and the bronchi are not separately visualised
But in the above mentioned conditions, there is opacification of the alveoli due to various reasons (eg: fluid accumulation is pulmonary oedema)
Due to this reason, the bronchi stands out as radioluscent in contrast to the adjacent alveoli that are radio opaque
Visualisation of air bronchogram helps in identifying the underlying pathology

Causes of superior vena caval syndrome

pgblazer — Thu, 13 Jan 2011 12:23:48 +0000

Superior vena caval syndrome refers to the symptoms that arise due to obstruction to the superior vena cava
90% of superior vena caval syndrome is caused by malignancies
Among malignancies, lung cancer is the most common cause followed by lymphomas
Other causes of superior vena caval syndrome include thymomas, metastatic breast carcinomas, metastatic genitourinary and gastrointestinal cancers
Among different types of lung cancer, small cell variant has the highest chance of causing SVC syndrome
Approximately 8% of patients with small cell lung cancer develop SVC syndome compared to 4% of non small cell lung cancers

Reference:
Clinical hematology and oncology: presentation, diagnosis, and treatment By Bruce Furie

Pulmonology quiz – Episode 2

pgblazer — Wed, 24 Nov 2010 00:41:14 +0000

Question no.1 – Chest X-ray
Click on image for an enlarged view

Question no.2 – Chest X-ray
Click on image for an enlarged view

Spot the diagnosis and submit your answer to win exciting prizes!
Attempt both questions
Include an explanation to substantiate your diagnosis
Quiz master: Dr. C.P Rauf, Senior Consultant Pulmonologist, Chest Hospital, Calicut
Decision of the quiz master is final and binding on all participants
Contest open only to Indian Residents
Join the PG Blazer group on Facebook to get the latest updates
If you have any queries, Contact us.

Update – Pulmonology quiz, episode 2 has ended.

Bronchiolitis obliterans – Etiology, Pathogenesis, Clinical Features, Investigations and Management

pgblazer — Wed, 17 Nov 2010 01:55:32 +0000

Adenovirus – Bronchiolitis obliterans can occur as sequelae of adenovirus infection in children

Bronchiolitis obliterans is a rare chronic disease of bronchioles and smaller airways.
It is usually seen in the pediatric population after an episode of respiratory tract infection

Pathogenesis:

There is inflammation of the terminal bronchioles, respiratory bronchioles and alveolar ducts followed by obstruction of airway
Abnormal repair of epithelial injury is characteristic of bronchiolitis obliterans

Clinical features:

Initially there is fever, cough and dyspnoea followed by a transient improvement in symptoms
After the initial improvement, there is increased fever, productive cough and signs of respiratory distress

Investigations:

Chest X-ray may show hyperlucency
Pulmonary function test shows an obstructive pattern

Pulmonology quiz – Episode 1 – PFT report

pgblazer — Tue, 16 Nov 2010 17:08:56 +0000

Pulmonary function test – Flow volume curve
Click on image for an enlarged view

Spot the diagnosis and submit your answer to win exciting prizes!
Quiz master: Dr. C.P Rauf, Senior Consultant Pulmonologist, Chest Hospital, Calicut
Decision of the quiz master is final and binding on all participants
Contest open only to Indian Residents
Last date for submission of entries – 23rd November, 2010
Join the PG Blazer group on Facebook to get the latest updates
If you have any queries, Contact us

Update:

Episode 1 of Pulmonology quiz has ended. Thanks to all who participated. The results will be published soon and winners will be notified by email. You can now participate in the Second episode of Pulmonology quiz.

Update 2:

The results are out! The correct answer is Vocal cord dysfunction syndrome. Unfortunately none gave the correct answer…

Mass lesion – Left lungs – X-ray

pgblazer — Thu, 28 Oct 2010 09:58:37 +0000

Mass lesion – left lung
Click on image for an enlarged view

X-ray chest posteroanterior view showing homogenous haziness in left lung – upper and mid zones
Elevation of left dome of diaphragm – due to volume loss secondary to bronchus obstruction / diaphragmatic palsy secondary to phrenic nerve involvement
Mediastinal shift to left side
Hyperinflated right lung

Impression - Bronchogenic carcinoma

Factors in favour of diagnosis of bronchogenic carcinoma

Homogenous haziness (Tuberculosis can cause haziness of upper zone – due to fibrosis, but the appearance is non homogenous)
Volume loss can occur due to compression of bronchus by the tumour
Mediastinal shift due to volume loss
Phrenic nerve infiltration can cause diaphragmatic palsy

Massive pleural effusion

pgblazer — Sun, 10 Oct 2010 03:37:08 +0000

Massive pleural effusion – left side
Click on image for an enlarged view

X-ray chest anteroposterior view showing massive pleural effusion on left side and mediastinal shift to right
Patient presented with symptoms of dyspnoea, cough and fever for 1 week duration
On examination, breath sounds were absent on left side with stony dullness on percussion
Patient’s spouse was an active case of tuberculosis, hence tuberculous pleural effusion was suspected

Mass lesion – Chest X-ray

pgblazer — Tue, 03 Nov 2009 16:04:25 +0000

Chest X-ray showing a mass lesion in the left upper and middle zones

(Click the above image to view an enlarged version)

Invasive ventilation: Intermittent positive pressure ventilation (IPPV)

admin2 — Wed, 30 Sep 2009 07:51:47 +0000

IPPV is invasive and non-physiological, and hence reserved for cases where non-invasive ventilation is not suitable.

Terminology

PEEP: positive end expiratory pressure

Cycling: change from inspiration to expiration or the reverse. It can be volume cycled, pessure cycled, time cycled or flow cycled.

Modes of ventilation: controlled mode, assist controlled mode, assist mode

Controlled mode – every breath by the ventilator; even if the subject wants breath spontaneously, it is not permitted. Volume and pressure controlled modes are available.

Assist control mode – IMV and SIMV (synchronized intermittent mandatory ventilation). SIMV removes the chance of fighting with the ventilator. It is a popular weaning method. Both these modes are volume cycled.

Assist mode – ventilator only supports patient’s effort. eg. Pressure support ventilation (PSV). This mode is for weaning in a conscious patient. It will be disastrous in those prone for apnea.

While using volume controlled ventilation, peak airway pressure has to be monitored. In pressure controlled ventilation, the tidal volume has to be monitored for adequacy.

Positive end expiratory pressure (PEEP): Begin with 5 cm and step up if necessary. PEEP improves oxygenation by preventing alveolar collapse and recruits lung units. It increases FRC and prevents cyclical collapse of alveoli. PEEP can reduce cardiac output and overdistension of normal units.

Sedation / muscle relaxation for IPPV

Sedation is necessary for the person to tolerate ventilation. Midozolam or propofol are preferred. Instead of bolus doses, infusions may be better. Muscle relaxants are seldom used now-a-days in the ICU setting as relaxatants have their on problems. Relaxants may be used initially. But good sedation has to be given before giving relaxants.

Ventilator induced lung injury (VILI)

Causes: Barotrauma, Volutrauma, Biotrauma, Shear injury, PEEP, Peak pressure

Ventilator associated pneumonia (VAP) has a mortality of about 30%

Prevention of VILI:

Permissive hypercapnia – accept higher PaCO2 upto 60 mm Hg, limit airway pressue (<35 cms), low tidal volume (6 ml/kg)

Permissive hypoxia - accept lower level of PO2.

Weaning: Graduallly reduce ventilatory support using SIMV or PSV or T piece ventilation.

Oxygen therapy

admin2 — Wed, 30 Sep 2009 06:35:51 +0000

Oxygen therapy can be normobaric or hyyperbaric. During oxygen therapy, ventilation and airway maintenance should be adequate so that oxygen reaches the lung for gas exchange. Reserve of oxygen in the body is 1.5 litres, which lasts for about 6 minutes in circulatory arrest assuming a consumption of 250 ml/min. Hb contains 800 ml and alveoli contains about 400 ml of oxygen. Pre-oxygenation prior to induction of anaesthesia leads to denitration and increase in the alveolar oxygen content, enabling tolerance of longer period of apnea.
Circulatory gradient of oxygen: Oxygen partial pressure decreases gradually from the alveoli to the blood and finally to the mitochondria.

Pasteur point: Critical PO2 below which mitochondrial oxygen transport cannot occur (less than 1 mm Hg).
Global oxygen delivery (oxygen flux): Total amount of oxygen delivered to the tissue.
Oxygen extraction ratio: how much oxygen is extracted at tissue level – normal extraction is about 20-30%. It can increase in situations of oxygen deficit.

Oxygen dissociation curve: Shift to right of the oxygen dissociation curve means oxygen affinity to Hb is decreased so that oxygen delivery to tissue is increased. The opposite occurs in a shift to left of the oxygen dissociation curve.

Hypoventilation: decreases arterial PO2 and increases arterial PCO2.

Ventilation perfusion mismatch: either normally perfused, but poorly ventilated or normally ventilated and poorly perfused.

Right to left shunts: Physiological right to left shunt contributes about 2-3% desaturation. Pathological shunts can occur in lung diseases, inctracardiac shunts and extracardia shunts like patent ductus arterious.

Diffusion impairment: No limitation in normal subjects. Exercise induced diffusion abnormality in patients with lung disease.

Role of oxygen therapy in different types of hypoxia:

Supplemental oxygen is useful in hypoxic hypoxia. Oxygen therapy may be useful in anemic hypoxia along with correction of the abnormality. Supplemental oxygen is useful along with other modalities of treatment in stagnant hypoxia also. But it is not useful in histotoxic hypoxia.

Oxygen therapy systems: Low flow system and high flow systems are available.

Low flow systems: Nasal prongs and catheters, face masks, mask with reservoir bags. Usually they are used to deliver 2-4 litres of O2 per minute. 3-4% of FiO2 increase can be expected with one litre per minute flow rate. Low flow systems are inexpensive and easy to use.
Face masks can supply FiO2 of 0.4 – 0.6. Addition of reservoir to face mask increases reservoir capacity to 750 – 1250 ml and increases the FiO2 levels to 0.6 – 0.8. Partial rebreathing and non-rebreathing masks are also available, depending on the type of valves. In non-rebreathing mask, if the bag collapses completely during inspiration, the oxygen flow rate is inadequate.

High flow systems (Venturi device)
Delivers constant FiO2. There is colour coding of masks for the FiO2 achievable and the oxygen flow rate recommended.

Monitoring oxygen therapy

Patient clinical status – symptomatic improvement
Measurement of ABG and SPO2

Oxygen therapy in special situations

COPD: Hypercapnia is a problem which can occur due to loss of hypoxic drive for ventilation. Never withold oxygen therapy for fear of abolishing hypoxic drive.

Oxygen toxicity

Can occur with 100% oxygen for 12 hrs, 80% oxygen for 24 hrs or 60% oxygen for 36 hrs.
All these are in those with normal lung – can occur with lower levels in those with lung disease. A safe level for those with normal lung is 50%. If there is no response with these safe levels, addition of other modalities like CPAP have to be considered.
Home oxygen therapy devices:

Compressed cylinders, oxygen concentrator and liquid oxygen cylinders are the devices available for home oxygen therapy.

Indication for long term oxygen therapy: Hypoxemia at rest (PaO2 less than 55 mm Hg), borderline hypoxemia or hypoxemia with exercise.

Pneumomediastinum

admin2 — Sat, 05 Sep 2009 11:06:16 +0000

Continuos diaphragm sign in pneumomediastinum Continuos left hemidiaphragm sign in lateral view Air anterior to heart in pneumomediastinum Halo sign in pneumopericardium Related Articles ...

Swine Influenza A pandemic: H1N1 Virus

admin2 — Thu, 30 Apr 2009 00:47:25 +0000

Swine Influenza A outbreak has started in March, 2009 in Mexico. The number of suspected cases has increased to about 2000 while the death toll is increasing. Confirmed cases has been reported from the United States, Spain, Scotland and Canada. World Health Organization has increased the pandemic alert level from 3 to phase 4, meaning that “that the likelihood of a pandemic has increased, but not that a pandemic is inevitable”. Human to human transmission has evolved as cases without any contact with swine what so ever have occurred.

Swine Influenza A manifests with fever, cough, sore throat, body aches, headache, chills, fatigue and sometimes with diarrhea and vomiting. The possibility of Swine Influenza A should be considered in any person who has had contact with cases or travelled to an area with confirmed cases during the preceding 7 days.

Treatment of Swine Influenza A is mainly supportive with rest, fluids, cough suppressants, antipyretics and analgesics. Swine Influenza A (H1N1) virus is susceptible to antivrial agents oseltamivir and zanamivir. Antiviral therapy has to be initiated within 48 hours of onset of symptoms to be effective. Recommended duration of treatment with antiviral agents is for 5 days. Some benefits may be there even if antiviral treatment is started after 48 hours.

The usual influenza vaccine is not effective against Swine Influenza A. Antiviral prophylaxis, both pre exposure and post exposure have been recommended in those at high risk of acquiring the infection.

Vesicular Breath Sounds : Mechanism of formation

pgblazer — Thu, 09 Apr 2009 12:39:03 +0000

Vesicular breath sounds refers to the breath sounds heard over the various lung areas. The term ‘vesicular breath sounds’ was coined by Lennac. It was named so due to the belief that they are produced by air flowing through the alveoli. But it a misnomer. Vesicular breath sounds are in fact produced by the air flowing through the bronchi and the bronchioles. But they have a different character (low intensity, low pitch, expiratory phase lasting 1/3 of inspiration with no gap between expiration and inspiration) from the bronchial breath sounds (high intensity, high pitch, expiratory phase lasting as much as inspiration) normally heard over the trachea.

So why does vesicular breath sounds differ from bronchial breath sounds even though both of them are produced by air flow through tubes(bronchi/trachea)? That’s because the air in the alveoli act as a muffler which modifies the characters of the vesicular breath sounds. It allows only the low frequency sounds to be conducted to the surface. Thus vesicular breath sounds are low intensity and low pitch. The expiratory phase is short because the breath sounds produced in the later 2/3 of expiration is mainly composed of high pitch sounds which are cut off.

Bronchial breath sounds can be heard over the lung areas in certain pathological conditions in which the air in the alveoli lost. It can be either due to collapse of lung with patent airways or due to filling of alveoli with pus (pneumonia), blood (pulmonary hemorrhage) or serum (pulmonary edema). In both these cases the muffling action of the air in the alveoli is lost and bronchial breath sounds are heard over lung areas. The cause of bronchial breath sounds can be identified by looking for the presence of adventitious sounds. If there is fluid in the alveoli, the bronchial breath sounds are asociated with crackles. Whereas in case of a collapse, there are no associated crackles heard.

Tracheal shift to right on X-ray chest PA view

admin2 — Sat, 28 Feb 2009 07:29:10 +0000

Tracheal shift to right on X-ray chest PA view

Tracheal air column is seen shifted to right on X-ray chest PA view. It indicates a loss of volume of the right upper lobe of the lung, either due to collapse or fibrosis. Tracheal can also be pushed to the right due to a massive pleural effusion on the left side. But no pleural effusion is seen on the left side.

Pleural effusion – left

admin2 — Wed, 31 Dec 2008 01:33:53 +0000

Click on the image for an enlarged view

Pleural effusion - left

Homogenous opacity with higher level towards the axilla on the left side is characteristic of a large pleural effusion on the left side. Tracheal and mediastinal shift to the right side is also evident. Pleural effusion can be either a transudate as in heart failure or exudate as in infections, inflammatory disorders or malignancy. Transudate is identified as a clear fluid with low protein and cell content. Exudate is straw coloured and has high protein and cell count. Hemorrhagic effusion is seen in malignancies. Careful survey of the film for evidence of malignancies and rib erosion is needed. Pleural effusion in heart failure is most commonly bilateral. If it is unilateral, it is more common on right side, possibly because of larger surface area of the right lung permitting more transudation in heart failure.

PG Blazer » Pulmonology

Pneumonia – predisposing factors

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Air bronchogram – Mechanism, Causes

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Causes of superior vena caval syndrome

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Pulmonology quiz – Episode 2

Question no.1 – Chest X-ray Click on image for an enlarged view

Question no.2 – Chest X-ray Click on image for an enlarged view

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Bronchiolitis obliterans – Etiology, Pathogenesis, Clinical Features, Investigations and Management

Adenovirus – Bronchiolitis obliterans can occur as sequelae of adenovirus infection in children

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Pulmonology quiz – Episode 1 – PFT report

Pulmonary function test – Flow volume curve Click on image for an enlarged view

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Mass lesion – Left lungs – X-ray

Mass lesion – left lung Click on image for an enlarged view

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Massive pleural effusion

Massive pleural effusion – left side Click on image for an enlarged view

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Mass lesion – Chest X-ray

Chest X-ray showing a mass lesion in the left upper and middle zones

(Click the above image to view an enlarged version)

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Invasive ventilation: Intermittent positive pressure ventilation (IPPV)

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Oxygen therapy

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Pneumomediastinum

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Swine Influenza A pandemic: H1N1 Virus

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Vesicular Breath Sounds : Mechanism of formation

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Tracheal shift to right on X-ray chest PA view

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Pleural effusion – left

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Question no.1 – Chest X-ray
Click on image for an enlarged view

Question no.2 – Chest X-ray
Click on image for an enlarged view

Pulmonary function test – Flow volume curve
Click on image for an enlarged view

Mass lesion – left lung
Click on image for an enlarged view

Massive pleural effusion – left side
Click on image for an enlarged view