THE LUNG AND HIV Flashcards
What percentage of HIV positive patients will experience at least one episode of respiratory disease over their lifetime?
60%
Are HIV positive patient with a normal CD4 count any more prone to lung infections than the general population?
Yes - but to the same typical community-acquired infections
What are the HIV associated respiratory tract infections?
Acute bronchitis
Acute sinusitis
Chronic sinusitis
Bronchiectasis
Bacterial pneumonia
Tuberculosis
Pneumocystis jirovecii pneumonia - PCP
Cryptococcus neoformans pneumonia
Histoplasma capsulatum
Influenza A
What are the organisms that most commonly cause bronchitis?
Streptococcus pneumonia
Haemophilus influenzae
What are the causative factors of bronchiectasis in an HIV positive patient?
Low CD4 count leads to recurrent bacterial, mycobacterial or pneumocystis infections. These eventually lead to bronchiectasis.
What imaging technique is used to diagnose bronchiectasis?
High resolution CT
How much more prone to bacterial pneumonia are HIV patients not taking cART?
6 - 10 times more likely
What group of HIV positive patients are particularly prone to bacterial pneumonia?
IVDUs
What is the organism most commonly responsible for bacterial pneumonia in HIV positive patients?
S. pneumoniae followed by H. influenzae
What does bacterial pneumonia look like on a radiograph of someone who is HIV positive?
More frequently atypical, mimicking PCP in up to half of cases.
What can we do to reduce risk of bacterial pneumonia in HIV positive patients?
Immunisation with 23-valent pneumococcal vaccination at diagnosis of HIV and at 5 years post diagnosis
cART to keep CD4 count high
What type of organism is Pneumocystis jirovecii?
Fungus
Which HIV positive patients are most at risk of PCP?
Those who are unaware of their diagnosis: it is a common presenting complaint that leads to HIV diagnosis
Those who do not tolerate or adhere to their cART
What are the clinical features of PCP?
Non-productive cough
Progressive exertional breathlessness
Several days to weeks duration
With or without fever
Chest is usually clear on auscultation
End-inspiratory crackles are very occasionally heard
What does a typical chest radiograph of someone with PCP looking like?
In early cases, 10% of cases will have normal looking chest x-ray
Most common features are bilateral, perihilar interstitial infiltrates - more clearly seen on CT scan
Progresses to diffuse alveolar shadowing over a period of a few days
What are the atypical features of a chest radiograph of someone with PCP present in up to 20% of cases?
Upper zone infiltrates resembling TB
Hilar/mediastinal lymphadenopathy
Intrapulmonary nodules
Lobar consolidation
How do we definitively diagnose PCP?
Sputum culture often reveals nothing
Bronchoalveolar lavage is needed to demonstrate PCP
However, patients are normally treated empirically especially if they have CD4 count less than 200
How clinically stratify severity of PCP?
Mostly using PaO2 and SaO2
Mild:
PaO2 more than 11.0
SaO2 more than 96%
Moderate:
PaO2 between 8.1 - 11.0
SaO2 between 91 - 96%
Severe:
PaO2 less than or equal to 8.0
SaO2 less than 91
What is the first line treatment in the management of PCP?
Co-trimoxazole BD or QDS for 21 days
Mild: PO
Moderate to severe: IV
Most will need admitting to ITU
What are the two medications contained within co-trimoxazole?
Sulfamethoxazole 100 mg/kg/day
Trimethoprim 20 mg/kg/day
What is the second line treatment in the management of PCP if co-trimoxazole fails?
MILD / MODERATE:
Clindamycin-primaquine
OR
Dapsone with trimethoprim
OR
Atovaquone
SEVERE:
Clindamycin-primaquine
OR
IV pentamidine
What additional medication should patients with PCP who present with a PaO2 of less than 9.3 kPa be given?
Glucocorticoids within 72 hours of starting anti-PCP treatment
What are the indications for prescribing prophylaxis of PCP?
CD4 count of less than 200 cells/microlitre
CD4 count of less than 14% of total lymphocytes
History of another AIDS defining diagnosis - eg Kaposi
All patients after an episode of PCP (secondary prophylaxis)
What criteria must be met before a patient can come off secondary prophylaxis of PCP (ie post having the disease)?
Must be on cART
Have sustained increased in CD4 count over 200 cells/microlitre
Undetectable plasma HIV RNA
All for over 3 months
What is the first choice drug and dose for PCP prophylaxis?
Co-trimoxazole - 480 mg OD or 960 mg 3 times weekly
What are the second choice drugs that can be used for PCP prophylaxis?
Nebulized pentamidine
Dapsone and pyrimethamine
Atovaquone
What are the two ways that pulmonary cryptococcal infection can present?
Either as a primary infection of lung
OR
As part of disseminated infection with meningitis with/without crytococcaemia
What are the clinical features of pulmonary cryptococcal infection?
Chest is often clear
May reveal some crackles
Signs of disseminated cryptococcosis including diarrhoea, meningism and cutaneous lesions.
What are the radiographic features of pulmonary cryptococcal infection?
Focal or diffuse interstitial infiltrates
Focal masses
Mediastinal or hilar lymphadenopathy
Nodules or effusion
How do we diagnose pulmonary cryptococcal infection?
Find cryptococcus neoformans in respiratory secretions or lung tissue (bronchoalveolar lavage)
How do we treat pulmonary cryptococcal infection?
Fluconazole
OR
Liposomal amphotericin and flucytosine
How frequent is primary pulmonary histoplasmosis?
Not at all. It almost invariably occurs as part of a disseminated infection.
What are the typical features of histoplasmosis in an HIV patient?
Typically subacute presentation of weight loss and fever
Non-productive cough
Dyspnoea
Hepatosplenomegaly
What will a chest radiograph of someone with pulmonary histoplasmosis show?
Often normal
Widespread small nodules (less than 4mm) in 1/3rd of cases
How do we diagnose pulmonary histoplasmosis?
Bronchoalveolar lavage or lung tissue
Serum 1-3 Beta D glucan levels may be elevated
How do we treat mild histoplasmosis?
Itraconazole
How do we treat more severe histoplasmosis?
Liposomal anphotericin
What are the risk factors for aspergillus infection?
Neutropenia (therefore not that common in HIV)
Corticosteroid therapy
What are the clinical features of aspergillus infection?
Non-specific
Cough
Fever
Dyspnoea
Pleuritic chest pain can occur
Haemoptysis can occur
How do we diagnose aspergillus infection?
Identification in sputum or lung tissue
Serum 1-3 Beta D glucan levels may be elevated
How do we treat aspergillus infection?
Voriconazole
OR
Liposomal amphotericin
How much more common is influenza A in HIV positive patients?
It isn’t more common but there is a greater risk of more severe disease
What are the typical features of influenza A in HIV positive patients?
Coryzal symptoms
Fever
Headache
Myalgia
How is influenza A diagnosed?
Detection of viral antigen or RNA is nasopharyngeal aspirate or nasal swab
What treatment can be given to HIV positive patients diagnosed with influenza A?
Oseltamivir (Tamiflu) PO - neuraminidase inhibitor
Zanamivir (Relenza) INH / IV - neuraminidase inhibitor
Which HIV patients are most at risk of developing pulmonary CMV infection?
Those with CD4 count less than 100
Those with another diagnosis such as PCP
How do we diagnose pulmonary CMV infection?
Characteristic intranuclear and intracytoplasmic inclusions in bronchoalveolar lavage fluid or lung tissue
What are the non-malignant, non-infectious pulmonary conditions that HIV positive patients are at an increased risk of developing?
Non-specific pneumonitis
Lymphocytic interstitial pneumonitis
COPD
Pulmonary arterial hypertension
Pneumothorax
What is non-specific pneumonitis?
Mimics PCP but often at higher blood CD4 counts
How is non-specific pneumonitis diagnosed?
Biopsy: Transbronchial, Video assisted thoracoscopic surgery or open lung
How do we treat non-specific pneumonitis?
Most episodes are self limiting
Prednisolone may be beneficial
Which group of HIV positive patients are most commonly affected by lymphocytic interstitial pneumonitis?
Children
What are the clinical features of lymphocytic interstitial pneumonitis?
Clinically resembles idiopathic pulmonary fibrosis
Slowly progressive dyspnoea
Cough
What does a typical chest radiograph of a patient with lymphocytic interstitial pneumonitis look like?
Bilateral reticulonodular infiltrates
How do we definitively diagnose lymphocytic interstitial pneumonitis?
Biopsy
How do we treat lymphocytic interstitial pneumonitis?
cART
How much more common is pulmonary arterial hypertension in HIV positive patients?
6 - 12 times more common
What should be excluded in all HIV positive patients who present with pneumothorax?
PCP
