Respiratory Flashcards
Gas exchange in COPD. What happens?
PaO2 is near normal until FEV1 is decreased to 50% of predicted
Elevation of PaCO2 is not expected until FEV1 is
What is shunting? Causes?
VQ ratio is 0
Alveoli are perfused with blood as normal but ventilation fails to supply the perfused region.
Causes:
Alveoli filled with fluid - Pulmonary oedema
Pneumonia
Which drug improves survival in PAH?
Prostacyclin (Bosentan) - reduced pulmonary vascular resistance (wood units)
Inhaled Bosentan provides relief but does not improve survival
May be combined with Sildenafil
Amlodipine can be used
PAH is defined as?
PAP > 25 mmHg
What is the Tx of a primary spontaneous pneumothorax?
If 3 cm, thoracentesis and catheter in place with a closed stop lock for 6 hrs.
Re-CXR, if resolved then discharge home.
Chest tube placement recommended if thoracentesis in unsuccessful (persistent air aspiration after 4 L removed) suggesting a bronchpleural communication leak
Hypersensitivity pneumonitis. Presentation, Ix?
Dyspnoea, cough, wheezing, crackles
Febilre episodes, fatigue and weight loss
Symptoms appear or worsen after antigen exposure
Ix:
CT chest- ground glass opacities, reticular,nodular
BAL - lymphocytosis > 20% consistent with Dx
CD4:CD8 ratio
What is the most common cause of a variable extrathoracic obstruction (impaired inspiratory loop)?
Vocal cord dysfunction is amongst the most common cause
Others:
Adenoid hyperplasia
Tracheomalacia
Complication of IVIG?
IVIG associated haemolytic anaemia
- +ve DAT
- reduced serum haptoglobin
- elevated reitculocytes
Treatment for asthma?
- Reliever PRN
- Inhaled glucocorticoid and PRN reliever
- ICS + LABA (LD) combined + Reliever PRN
- ICS + LABA (HD) + PRN releiver
Hepatopulmonary syndrome. Triad?
Mx?
Triad: Liver disease (usually portal HTN) Hypoxaemia - PaO2 15mmHg (or > 20 mmHg if age>65) Intrapulmonary vascular dilatations (contrast echo)
Mx:
Supportive
Transplant referral
Platypnea and Orthodeoxia are highly suggestive of Hepatopulmonary syndrome. What are they?
Platypnea
- increase in dyspnoea worse in the upright position and relieved by recumbancy.
- Improved by moving back to supine postion.
Orthodeoxia
- fall in arterial Oxygen tension (fall in sats >5% or PaO2 > 4 mmHg) when pt moves from supine to upright position
What is the hypoxia in hepatopulmonary syndrome due to?
VQ mismatch
diffusion limitation
AV shunting
Well’s criteria. Scores for low, moderate and high probability.
Low 6
Clinical signs of DVT = 3 No alternative Dx = 3 HR>100 = 1.5 Immobilisation or Sx in previous 4 weeks = 1.5 Previous DVT = 1.5 Haemoptysis = 1 Malignancy = 1
A score of 4.0 and -ve D-dimer result may safely exclude a PE in a large proportion of patients with a suspected PE.
What is the major toxic effect of a benzo overdose? Mx
Respiratory depression
Mx:
Supportive care
Flumazenil is a competitive antagonist at benozodiazepine (GABA-A) receptors in the CNS.
Not much role for Mx of benzo overdose however indicated in the following:
- warranted in elderly or other patients with resp disease (COPD) where intubation should be avoided.
- Tx of CNS depression due to iatrogenic over Tx (e.g. procedural sedation)
- Benzo overdose resulting in compromised airway or breathing when intubation equipment/skills not available
Flumazenil.
MOA
Indication
Flumazenil is a competitive antagonist at benozodiazepine (GABA-A) receptors in the CNS.
Not much role for Mx of benzo overdose however indicated in the following:
- warranted in elderly or other patients with resp disease (COPD) where intubation should be avoided.
- Tx of CNS depression due to iatrogenic over Tx (e.g. procedural sedation)
- Benzo overdose resulting in compromised airway or breathing when intubation equipment/skills not available
signs of opiod overdose? Tx
Depressed mental state
decreased resp rate and decreases tidal volume
decreased bowel sounds
miotic pupils
Tx:
Naloxone - mu opiod antagonsit
Goal of naloxone is adequate ventilation not normal GCS
RFTs. How is obstruction defined? The
Defined on spiro by FEV1/VC ratio
RFTs. How do you define restriction?
Defined on static lung volume measurements by TLC
RFTs. How you define a mixed restrictive and obstructive picture?
Meets both critera:
Obstructive
Defined on spiro by FEV1/VC ratio
NSCLCa. Staging and corresponding Tx.
Staging: Stage I: 7 cm or invading structures e.g. RLN, trachea, great vessels Tx: Need MDT to decide on Tx Sx + adjuvant CTx OR Chemoradiation OR Palliative Rx
Stage IIIb:
N3 nodes (contrlateral mediastianal or hilar nodes, scalene nodes, or supraclavicular nodes)
Tumor with invasion of structures above + N2 nodes
Tx: Chemoradiation or palliative Rx
Stage IV
distant mets which include
- contrlaterla lung nodules
- PLEURAL noduels
- MALIGNANT PLEURAL OR PERICARDIAL EFFUSION
Tx:
Palliative RTx
However systemic Tx should be offered to all pts with ECOG 0-2
- Platinum doublet CTx e.g. cisplatin/gemcit 4-6 cycles. Prolongs OS and improves QOL.
- evidence that addition of bevacizumab to platinum doublet in non-squamous NSCLC results in improved RR, PFR, OS.
Pt with NSCLC, eGFR mutation with brain mets. Tx?
Still EGFR inhibitor, erlotinib.
MRI brain only performed if neurological symptoms. Not part of staging.
Pt with NSCLC and ALK mutation . Tx?
Crizotinib. On PBS now.
What does a +ve tuberculin skin test (TST) suggest?
TB acquisition (active or latent)
Non tuberculous mycobacterium (NTM)
BCG vaccine (if 1y 10% will have apositive TST)
Boosting (increased induration with each successive test)
False -ve
- immunocompromised
- recent aquisition, need to repeat test 8-12 weeks later
Is IGRA (QF gold and T-spot) more sensitive or specific than TST? What does a +ve result mean?
Equal or greater sensitivity, more specific than TST.
Measures T cell release found in MTB and some NTMs
Positive:
Latent or active Tb
Pt with +ve TST/QF, normal CXR and clinically well. Mx?
Tx with latent TB prophylaxis with isoniazid for 6-9 months or
CXR yrly for 2-3 years
Alternative Tx is Rifampacin for 4 months.
If compliant will reduce risk of reactivation by 90%
Pt with +ve TST/QF, CXR with Tb scar, clinically well. Mx?
CXR FU or Discharge
LTBI. What is the life time risk of active TB? RF?
10%
RF:
Most risky period is 2 years after acquisition
- should have repeat test 8-12 weeks later of 1st test -ve
Immunosuppression, esp T cell suppression
Who should you test for LTBI?
Those with recent acquisition
- should have repeat test 8-12 weeks later of 1st test -ve
Household contacts of TB
HCW exposed to active TB
Those at high risk of reactivation
- any T cell problem: HIV infection, post tranplant immunosuppression, lymphoma, leukemia
- Renal failure on dialysis
- Tx with biologics
AE of Isoniazid?
Raised LFTs
- if >3 x ULN, stop Tx
Peripheral neuropathy
- take with pyridoxine 25 mg OD
Causes of HAGMA?
Extra anions KIL U
Extra anions KIL U Ketones - DKA, EtOH, starvation Ingestion - salicylates, methanol, glycols Lactate - sepsis, dead gut, metformin Uraemia
Causes of NAGMA?
Loss of HCO3 somewhere
GUT- diarrhoea (neGUTive urine AG)
Kidney e.g. RTA, renal failure (positive urine AG)