PLAB 2 Procedural Skills 2 — Questions and Answers
Question 1: You need to insert a chest drain for a large pneumothorax. According to BTS guidelines, where is the safe triangle for insertion?
- The 2nd intercostal space, midclavicular line
- The triangle bordered by the anterior border of latissimus dorsi, the lateral border of pectoralis major, and a line superior to the horizontal level of the nipple (5th intercostal space), in the mid-axillary line (Correct answer)
- Anywhere on the posterior chest wall
- The 3rd intercostal space, mid-axillary line
Correct answer: The triangle bordered by the anterior border of latissimus dorsi, the lateral border of pectoralis major, and a line superior to the horizontal level of the nipple (5th intercostal space), in the mid-axillary line
BTS guidelines recommend chest drain insertion within the 'safe triangle': bordered by the anterior border of latissimus dorsi posteriorly, the lateral border of pectoralis major anteriorly, and a horizontal line at the level of the nipple inferiorly (approximately 5th intercostal space). This minimises risk to internal structures.
Question 2: During a PLAB 2 station, you are performing a peak expiratory flow rate (PEFR) measurement. The patient produces three readings: 320, 340, and 310 L/min. Which value should be recorded?
- The average of all three readings (323 L/min)
- The highest of the three readings (340 L/min), as per BTS guidelines (Correct answer)
- The lowest reading (310 L/min)
- The first reading only (320 L/min)
Correct answer: The highest of the three readings (340 L/min), as per BTS guidelines
BTS guidelines state that the highest of three technically satisfactory attempts should be recorded as the PEFR. This is because the best effort represents the patient's true maximum expiratory flow. The result is then compared to the patient's predicted value based on age, height, and sex.
Question 3: You are performing a digital rectal examination (DRE) as part of an abdominal examination station. Which of the following findings would be most concerning for rectal malignancy?
- A smooth, symmetrically enlarged prostate
- A hard, irregular, fixed mass with a loss of the normal mucosal pattern, which may be blood-stained on the examining finger (Correct answer)
- Soft haemorrhoids at the anal margin
- An empty rectum
Correct answer: A hard, irregular, fixed mass with a loss of the normal mucosal pattern, which may be blood-stained on the examining finger
Features suspicious for rectal malignancy on DRE include: a hard, irregular mass, fixation to surrounding structures, loss of normal mucosal pattern, and blood on the examining finger. Any suspicious mass requires urgent 2-week wait referral for further investigation (flexible sigmoidoscopy or colonoscopy).
Question 4: You are asked to perform a nasogastric (NG) tube insertion. After insertion, what is the gold standard method to confirm correct placement before use?
- Listen for air bubbles by injecting air while auscultating the epigastrium (whoosh test)
- Aspirate gastric contents and test with pH indicator paper — a pH of ≤5.5 confirms gastric placement. If unable to aspirate, request a chest X-ray to confirm the tip is below the diaphragm (Correct answer)
- Start feeding immediately and observe for symptoms
- Measure the external length of the tube only
Correct answer: Aspirate gastric contents and test with pH indicator paper — a pH of ≤5.5 confirms gastric placement. If unable to aspirate, request a chest X-ray to confirm the tip is below the diaphragm
NPSA (NHS Patient Safety) guidelines require pH testing of aspirate as the first-line method for confirming NG tube placement — pH ≤5.5 confirms gastric position. The 'whoosh test' (auscultation) is unreliable and must NOT be used. If aspirate cannot be obtained or pH is >5.5, a chest X-ray is needed before use.
Question 5: During a PLAB 2 station on IV cannulation, you attempt to insert a cannula but fail on the first attempt. What is the recommended maximum number of attempts by a single practitioner?
- One attempt only, then call a senior
- A maximum of two attempts — if both fail, seek assistance from a more experienced colleague or consider alternative access (ultrasound-guided, central venous) (Correct answer)
- Unlimited attempts until successful
- Three attempts, then use a larger gauge needle
Correct answer: A maximum of two attempts — if both fail, seek assistance from a more experienced colleague or consider alternative access (ultrasound-guided, central venous)
Best practice guidelines recommend a maximum of two attempts at IV cannulation per practitioner. Multiple failed attempts cause patient distress, tissue damage, and venous access compromise. After two failures, seek help from a more experienced colleague, consider ultrasound-guided insertion, or escalate to central venous access if appropriate.
Question 6: You are performing basic life support (BLS) on an adult. After confirming cardiac arrest and calling for help, what is the correct compression-to-ventilation ratio and depth of compressions?
- 15:2 ratio, 3 cm depth
- 30:2 ratio (30 compressions to 2 ventilations), at a depth of 5-6 cm, at a rate of 100-120 compressions per minute (Correct answer)
- 30:2 ratio, 8 cm depth
- 15:1 ratio, 4 cm depth
Correct answer: 30:2 ratio (30 compressions to 2 ventilations), at a depth of 5-6 cm, at a rate of 100-120 compressions per minute
UK Resuscitation Council adult BLS guidelines specify: 30 chest compressions to 2 rescue breaths, compression depth of 5-6 cm, compression rate of 100-120 per minute, allowing full chest recoil between compressions. Hands should be placed on the lower half of the sternum. Minimise interruptions to compressions.
PLAB 2 Procedural Skills 2
You need to insert a chest drain for a large pneumothorax.
According to BTS guidelines, where is the safe triangle for insertion?