CXR, ABG, ECG

Question 1

Whats the check for xray quality?

Answer 1

PRIM
P- Projection
R- Rotation (SP-clav dist)
I - Inspiration 7 ant ribs
M - Markings

Question 2

What are the structures to consider in a CXR?

Answer 2

• Heart 50%
• White = effusion if unilateral and solid. Pneumonia if unilateral and fluffy. Oedema if bilateral and fluffy. Fibrosis, bilateral and honeycomb
• Trachea - central, deviation towards a collapse and away from a pneumothorax
• Mediastinum can wide with right upper lobe collapse (tracheal dev) or aortic dissection (no trach)
• Blunted costophrenic angles in pleural effusions
• Sail shadow behind heart suggests left lower lobe collapse.
• Not clear apices - TB or tumor

Question 3

What are the ABCDE signs of pulm. oedema on CXR?

Answer 3

A - Alveolar oedema (bat wings)
B - Kerly B ligns (intersitital oedema)
C - Cardiomegaly
D - Diversion of blood to upper zones (upper zone vessels larger than lower)
E - Pleural effusions

Question 4

Whats the consideration for an arterial blood gas oxygen level for a patient on supplemental oxygen?

Answer 4

You would expect them to have a grossly higher level of PaO2 even if it falls within the normal range they can still be grossly hypoxic.

Question 5

Whats a trick method for calculating a normal PaO2?

Answer 5

Approximately: FiO2 - 10 in kPa (PaO2 should exceed this)

Question 6

How do we distinguish the types of respiratory failure on an ABG?

Answer 6

Type 1: low or normal PaCO2 i.e fast/normal breathing: Caused by damage to heart or lungs causing SOB

Type 2: High PaCO2. (slow/shallow breathing), blue bloaters of COPD. or neuromuscular failure or restrictive chest wall abnormalities.

Question 7

What are some tips and tricks for determining the cause of acid: base disturbance being resp or metabolic.

Answer 7

If only PaCO2 abnormal = Resp cause.

If only HCO3 = metabolic cause.

If both increased or decreased = compensation. Abnormal pH = partially compensated.

If PaCo2 and HCO3 abnormal in opposite directions then indicates coexistent metabolic and respiratory disease

Question 8

What are some rough causes of Resp acid and alkalosis, and meta acid and alkalosis?

Answer 8

Resp Alk: Rapid breathing; Anxiety or disease.

Resp acid: Type two resp. failure.

Metabolic alk: Vomiting, diuretics, and conns syndrome.

Metabolic acidosis: DKA, lactic acidosis, renail failure, intoxication; ethanol, methanol, ethylene glycol. Many causes. Anion gap further elucidates cause.

Question 9

Whats the mneumonic for remembering BBB and ECG changes?

Answer 9

William morrow:

LL
1st deflection of QRS; V1 = down (W), V6 = up (M)

RR
1st deflection of QRS; V1 = up (M), V6 = down (W)

Question 10

Describe the heart blocks:

Answer 10

First degree: Constant PR but is longer than 1 large square.

Second degree (Type 1) : Increased PR and then missing QRS

Second degree (type 2): 2-3 P waves for a QRS

Complete heart block: No association between P and QRS

Question 11

Whats the QRS width?

Answer 11

<3 small squares = no bundle branch block. 3+ = BBB

Question 12

Whats the height of QRS and indicates?

Answer 12

Add largest deflection in V1 and V6. If exceeds 3.5 large squares = left ventricular hypertrophy. If small complexes consider pericardial effusion

Question 13

What does ST elevation look like and indicate?

Answer 13

Infarction: elevated in SOME leads

Pericarditis: Saddle shaped and raised in ALL leads.

Question 14

What does ST depression look like and indicate?

Answer 14

Ischaemia or infarction: ST segment flat and depressed in SOME leads. - Check troponin to distinguish.

Digoxin tx: ST segment downsloping in all leads.

Question 15

What are some common T wave anomalies:

Answer 15

If more than 2/3rds of QRS throughout = peaked = hyperkalaemia.

Inversion: Normal in AVR and I (Top middle two leads), in other leads suggests old infarction or LVH