P year‎ > ‎Systematic teaching‎ > ‎

12.12.12 Respiratory lectures

PE
  • Risk factors
    • Smoking
    • Overweight
    • Cancer
  • VQ scan
    • Less radiation than CTPA
    • Takes 2-3 days to request + do
    • Only gives high, intermediate and low probabilities
    • Can only do if CXR is normal
    • Can do just the V bit if pregnant/radiation concern
  • RV strain pattern
    • RBBB
    • Right axis deviation
    • S1Q3T3
  • TTE
    • To look for cardiac signs of PE
      • Reduced output, RV strain
  • Thrombolysis
    • Via central line
    • Do on HDU
  • BTS don't recommend D-dimer if there is a high clinical suspicion of PE
  • Immediate management
    • Treatment-dose heparin
    • Oxygen
    • IV fluids
    • Look for a DVT
      • If there's evidence of DVT on ultrasound and clinical signs of PE, start treating
  • Long-term management
    • 3 - 6 months of anticoagulation
      • Target INR 2-3
    • Consider thrombophilia screen (off warfarin) if:
      • Recurrent PE
      • Less than 50
      • Family Hx
  • Indications for alteplase:
    • Massive PE
      • Collapse/hypotension
      • Unexplained hypoxia
      • Engorged neck veins
      • Gallop rhythm
    • Give 50mg bolus of alteplase
    • Must give 60 mins of CPR afterwards

PE risk factors

Risk factors for venous thromboembolism
Major risk factors: relative risk of 5-20Minor risk factors: relative risk of 2-4
Surgery:
  • Major abdominal/pelvic surgery
    or hip/knee replacement
    (risk lower if prophylaxis used).
  • Postoperative intensive care.
Obstetrics:
  • Late pregnancy.
  • Puerperium.
  • Caesarean section.
Lower limb problems:
  • Fracture.
  • Varicose veins - previous
    varicose vein surgery;
    superficial thrombophlebitis; varicose veins per se are not a risk factor. 
Malignancy:
  • Abdominal/pelvic.
  • Advanced/metastatic.
Reduced mobility:
  • Hospitalisation.
  • Institutional care.
Previous proven VTE:
  • Intravenous (IV) drug use
    (could be major or
    minor risk factor:
    no data on relative risk).
Other:
  • Major trauma.
  • Spinal cord injury.
  • Central venous lines.

 

Cardiovascular:
  • Congenital heart disease.
  • Congestive cardiac failure.
  • Hypertension.
  • Paralytic stroke.
Oestrogens:
  • Pregnancy (but see major risk factors for late pregnancy and puerperium).
  • Combined oral contraceptive.
  • Hormone replacement therapy.
Haematological:
  • Thrombotic disorders
    Consider this in cases of PE aged <40 years, recurrent VTE or positive family history.
  • Myeloproliferative disorders.
Renal:
  • Nephrotic syndrome.
  • Chronic dialysis.
  • Paroxysmal nocturnal haemoglobinuria.
Miscellaneous:
  • Chronic obstructive pumonary disease 
  • Neurological disability.
  • Occult malignancy.
  • Long-distance sedentary travel.
  • Obesity.
  • Other chronic diseases: inflammatory bowel disease, Behçet's disease.
Pneumonia
  • Bronchoscopy
    • If not expectorating
    • Lobar collapse
  • Urinary antigens for some organisms
  • HAP
    • Gram -ves
    • Pseudomonas
    • Anaerobes
  • Metronidazole vs Anaerobes
  • Multiseptated effusions are hard to drain

Pneumothorax
  • Types
    • Primary
    • Secondary
    • Iatrogenic
    • Traumatic
  • Clinical features
    • Tension
    • Open
    • Closed
  • Risk factors
    • Smoking (12% of smokers!)
    • Underlying lung pathology
    • Tall
    • Age >60
  • Small/Large cutoff:
    • 2cm space between chest wall and pleural line, at the level of the hilum
  • Give oxygen
    • Gets into the pleural space, and is reabsorbed quicker than nitrogen
  • Check CT for secondary pathology, e.g. blebs that might have popped
  • Drains
    • Seldinger
    • Argyle
  • Recurrence
    • 54% risk within 4 years
    • Esp. if still smoking
  • Chest drain management
    • Check swinging
    • If still bubbling, can use 5 cm water pressure to suck air out

Asthma
  • Formoterol
    • Rapidly acting beta2 agonist; Also long-acting
  • Peak flow
    • Measures upper/large airway function
    • => Good for asthma, but not for COPD (affects medium + small airways)
  • Do a blood gas in acute asthma only if sats < 92%
  • MgSO4
    • Antagonises calcium release in smooth muscle
    • Can only use once
    • Causes muscle weakness / resp. failure
  • Aminophylline
    • Xanthine derivative (c.f. tea when you have a cold)
    • Phosphodiesterase inhibitor and adenosine receptor antagonist
      • Some central mechanisms too
  • LTRAs have no proven benefit in acute asthma
  • Role for heliox?
  • No role for antibiotics in acute asthma - Exacerbation is usually viral
  • Asthma discharge criteria
    • Diurnal peak flow variation <25%
    • PEFR >75%
    • < 4 hourly nebs
    • Back on usual meds
    • Follow-up plan in place
      • With GP within 48hrs
      • Hospital within a month
      • Follow up for a year

COPD
  • Pathophysiology - Due to toxious stimuli
    • Elastin/connective tissue defect
      • Loss of elastic recoil
      • => Emphysema
    • Inflammation
      • Mucous plugging + airway defects
      • => Bronchitis
  • Admit to ICU if acidotic with pH <7.25

Anthonisen criteria
  • For antibiotic use in acute exacerbation of COPD
  • Need 2 out of 3 of:
    • Increased dyspnea
    • Increased sputum volume
    • Increased sputum purulence

Notes
  • Resp. failure is pO2 < 8 kPa
  • Must use LMWH to anticoagulate if pregnant, not warfarin
  • CTPA => 14% increased risk of breast cancer
  • Systemic inflammation => Cachexia
  • Doxapram = Centrally acting respiratory stimulant
    • No use in COPD
    • Used in drug overdose etc
  • pH kills patients, not CO2
Comments