Pulse oximetry is a standard medical technique used to measure blood oxygen levels by shining light through a patient's fingertip...
GMAT Information and Ideas : (Ideas) Questions
Pulse oximetry is a standard medical technique used to measure blood oxygen levels by shining light through a patient's fingertip and analyzing how much light is absorbed. This non-invasive method typically provides accurate readings within seconds and is used routinely in hospitals worldwide. Nevertheless, a physician claims that pulse oximetry often fails to give reliable measurements for certain patients.
Which detail, if true, would most directly support the physician's claim?
Pulse oximetry was first developed in the 1970s and has been refined over decades.
Patients with heavily pigmented skin or thick calluses may produce inaccurate pulse oximetry readings.
Blood oxygen levels below 90% typically indicate a medical emergency.
Pulse oximetry is less expensive than arterial blood gas analysis.
Step 1: Decode and Map the Passage
Part A: Create Passage Analysis Table
| Text from Passage | Analysis |
|---|---|
| 'Pulse oximetry is a standard medical technique used to measure blood oxygen levels by shining light through a patient's fingertip and analyzing how much light is absorbed.' |
|
| 'This non-invasive method typically provides accurate readings within seconds and is used routinely in hospitals worldwide.' |
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| 'Nevertheless, a physician claims that pulse oximetry often fails to give reliable measurements for certain patients.' |
|
Part B: Provide Passage Architecture & Core Elements
Main Point: While pulse oximetry is widely considered a reliable standard technique, a physician argues that it often produces unreliable measurements for certain types of patients.
Argument Flow: The passage establishes pulse oximetry as a standard, effective medical technique used globally, then presents a physician's contrasting claim that challenges this reliability for specific patient groups.
Step 2: Interpret the Question Precisely
This is a fill-in-the-blank question asking us to choose the best logical connector. The answer must create the right relationship between what comes before and after the blank.
Step 3: Prethink the Answer
- The physician claims that pulse oximetry 'often fails to give reliable measurements for certain patients.'
- For evidence to support this claim, we need information that:
- Identifies specific types of patients who experience problems
- Shows that the technique actually produces inaccurate or unreliable results for these groups
- Demonstrates this is a real limitation, not just a theoretical concern
- The right answer should provide concrete evidence that there are indeed identifiable patient groups for whom pulse oximetry doesn't work reliably.
Pulse oximetry was first developed in the 1970s and has been refined over decades.
- Historical information about when pulse oximetry was developed and refined.
- This doesn't address current reliability issues with specific patients.
- Development timeline is irrelevant to whether the technique fails for certain people.
Patients with heavily pigmented skin or thick calluses may produce inaccurate pulse oximetry readings.
- Identifies specific patient characteristics that cause inaccurate readings.
- Directly demonstrates that certain patients do experience reliability problems.
- Perfectly matches the physician's claim about 'certain patients' having measurement issues.
Blood oxygen levels below 90% typically indicate a medical emergency.
- Information about what low oxygen levels indicate medically.
- This doesn't address whether pulse oximetry accurately measures those levels in all patients.
Pulse oximetry is less expensive than arterial blood gas analysis.
- Cost comparison between pulse oximetry and another method.
- Cost information doesn't relate to accuracy or reliability concerns.