Respiratory Flashcards
Where is the central area for stimulation of inspiration
medulla- dorsal respiratory group
Where are the central chemoreceptors
Near ventral surface of the medulla
Anion Gap Equation
ANION GAP:
= Na – (Cl + HCO3) – 12
Normal anion gap = 12mmol/L +/- 2
Osmolar gap equation
OSMOLAR GAP: calculate if anion gap is increased and unclear cause
Difference in measured and calculated osmolality
Should be <10
Calculated osmolality =
(2xNa) +Glucose +Urea
Measured osmolality – calculated osmolality = Osmolar gap
Lung volume at which pulmonary vascular resistance is lowest
FRC
Definition of pulsus paradoxus
an inspiratory drop in blood pressure of 10mmHg or more during normal breathing
A-A Gradient equation
• PA02 = (Patm – Pwater)FiO2 – PaCO2/0.8
= 150 – PaCO2/0.8
• A-a gradient = PA02 – Pa02
= 150 – PaCO2/0.8 – PaO2
Indirect Bronchoprovocation drugs
Mannitol, adenosine monophosphate, eucapnic hyperventialtion
Direct Bronchoprovocation drugs
methacholine, histamine
Which histo subtype of malignant mesothelioma has the worst/best prognosis
Sarcomatoid - worst
Papillary mesothelioma -best
Mx of mesothelioma
Unresectable - Platinum +Pemetrexed
+/- bevacizumab
If progess on first line: Gemcitabine
Causes of Upper Lung Fibrosis
Upper lobe - Coal miners pneumoconiosis - Hypersensitivity pneumonitis (extrinsic allergic alveolitis)/ Histiocytosis - Ank Spond - Radiation - TB Silicosis/Sarcoidosis
Left shift in O2 curve
↓H+ (↑pH) and CO2 ↓Temperature ↓DPG-phosphate from metabolism COHb MetHb ↑HbF
Right shift in O2 curve
↑H+ (↓pH) and CO2 ↑Temperature ↑2-3 DPG-phosphate from metabolism Cyanide ↓HbF
Right shift in O2 curve
↑H+ (↓pH) and CO2 ↑Temperature ↑2-3 DPG-phosphate from metabolism Cyanide ↓HbF
Flow Volume loop: Flat bottom
Dynamic extrathoracic obstruction
Cause:
Structural or functional vocal fold abnormalities
Laryngomalacia
Tracheomalacia of the extrathoracic trachea
Flow Volume loop: Flat top
Dynamic intrathoracic obstruction
Cause:
Tracheomalacia of intrathoracic airway
Bronchogenic cysts
Malignant tracheal lesions
Flow Volume loop: Flat both top and bottom
Fixed obstruction
Cause:
Firm tracheal lesions (e.g. tracheal stenosis)
Extraluminal Tracheal Obstruction (goitre)
Flow Volume loop: Sawtooth
Cause:
OSA
NMD
Parkinsons
Methaemoglobinaemia
- Iron is in Fe3+ state rather than Fe2+, so reduced oxygen affinity for Hb while remaining O2 bound to normal Hb binds tighter (left shift)
- Can be congenital (eg. Haemoglobin M disease or acquired (eg. Dapsone)
- Cyanosis with normal PaO2.
- Treatment: methylene blue
Lights Criteria
- Pleural fluid protein/serum ratio >0.5
- Pleural fluid LDH/serum LDH ratio >0.6
- Pleural fluid LDH > 2/3 the upper limits of the laboratory’s normal serum LDH
Transudative pleural effusion
Serum: Pleural protein - >31g/L most likely transudative
If <31 g/L consider measuring albumin gradient (particularly if hepatic hydrothorax is likely)
• >12 g/L most likely transudate
• Ratio <0.6 the most sensitive for transudate
Mesothelioma malignancy markers
– Mesothelin, Fibulin 3; SMRP (Serum mesothelin related protein good for sarcomatoid mesothelioma), Calcretin
Pleural pH when testing for empyema
• Pleural pH is only reliable if checked within 1 hour of obtaining otherwise it begins to rise; pleural glucose <2.2 is just as sensitive as pH and can be stable for up to 24 hours