Bedside Spirometry Two Days After Open Abdominal Surgery
A 70-year-old man is 2 days out from open abdominal aortic aneurysm repair. The surgical team wants bedside spirometry "to track his lungs" because he is febrile with coarse crackles at both bases. He is propped at 30 degrees, wears an abdominal binder, has a nasogastric tube and a patient-controlled morphine pump, and rates incisional pain 6/10 at rest; he winces when asked to cough. Room-air SpO2 is 93%. He is drowsy but oriented, and his last PCA bolus was 15 minutes ago. Your lab protocol calls for upright seated posture and at least three acceptable efforts with the best two FEV1 values within 150 mL. The nurse asks whether you can "just get it done quickly" before the surgeon rounds in 10 minutes.
1. Do you run the test now, modify it, or defer? Justify the decision physiologically.
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Modify and, if modification fails, defer.
- Effort is the measurement. An FVC is interpretable only if it comes from a maximal effort initiated at full inflation. Three variables here each degrade effort: uncontrolled incisional pain (he won't reach RV), a PCA bolus 15 minutes ago (peak sedation and blunting of the drive to push through pain), and a 30-degree recline, which lowers FRC and typically costs 10-20% of seated FVC.
- The result would be uninterpretable, not merely low. With those three stacked, a reduced FVC cannot be attributed to atelectasis rather than splinting and position. A non-acceptable number is worse than no number, because it gets charted and trended as if it were real.
- Practical plan: request analgesia review, wait 20-30 minutes, raise the head of bed to at least 45-60 degrees if hemodynamically allowed, use a nose clip, demonstrate the maneuver, and coach hard. Accept only efforts meeting end-of-test and repeatability criteria.
- If he still cannot: record "unable to perform acceptable spirometry" with the reasons, and offer a slow vital capacity or incentive-spirometer volumes purely as a trend, not as an FVC.
2. You obtain two efforts: FVC 1.9 L and 2.2 L, FEV1 1.6 L and 1.8 L, with a 30% difference between them and an abrupt, ragged end-of-test. What goes in the report and chart, and what do you say to the surgical team?
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The repeatability criterion is not met: the FVCs differ by 0.3 L (about 14%) and the FEV1s by 0.2 L, and neither effort has an acceptable plateau, so no single "best" value can be defended. The correct report is a failed study with the reason, plus the raw values labeled as non-diagnostic.
- Chart: body position, time of last opioid and pain score, number of efforts attempted, which acceptability criteria failed (end-of-test, repeatability), and the values explicitly flagged as non-interpretable.
- Tell the team: "These numbers underestimate his true FVC because of pain, sedation, and position, so do not compare them to predicted values or use them to diagnose restriction. Use the trend only if the technique is reproduced the same way." If they want a real answer, the test must be repeated when he is comfortable, alert, and sitting upright.
- Offer an alternative that answers their actual question - is he worsening? - such as serial incentive-spirometer inspired volumes and SpO2 at a consistent position, and set a trigger (for example, a falling inspired volume or rising oxygen need) for repeating proper spirometry.
3. The team insists a number is needed to decide on bronchodilator therapy. How do you respond, and what would make you escalate the effort?
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Bronchodilator responsiveness is a comparison between two technically acceptable forced maneuvers; if the baseline is not acceptable, the comparison is meaningless. Reversible airway disease cannot be diagnosed from a test the patient could not perform, and a "response" built on two ragged efforts would be pure noise.
To make a defensible test, all of the following need to line up:
- Pain controlled enough that he can sit upright and sustain a forceful blast.
- Alert and not within the sedating window of a PCA bolus.
- Seated posture with a good seal, nose clip, and coached demonstration.
- At least three efforts meeting end-of-test and repeatability criteria, at baseline and again after the bronchodilator using the same technique and position.
If those cannot be achieved before discharge, the honest recommendation is to defer the bronchodilator study to an outpatient visit where technique can be controlled, and to manage him in the meantime on clinical grounds. Document that recommendation so it is clear the limitation is technical, not a negative result.