SpiroClinic Pro, our clinical ultrasonic spirometer, measures a great deal of values in order to give you the best picture of the patient's lung health. We went over how to set it up, and how to use it in our previous guides. Now, let's look over what you will see on the PDF report, and what these signify.
The general layout of a PDF report
There are two options when it comes to generating a PDF report: the app will ask you to choose between a basic report and a detailed one. A detailed report will have the basic report as the first page, this will be a condensed summary of the results.
The first things you will see once you open the PDF report will be the general information about the patient: name, weight, height, diagnosis, etc. These will be followed by the clinic's information: operator name, temperature, humidity, date of the test, etc.
If the test included a post-test as well, the bronchodilator information will be seen under the clinic information. The test results will be divided by pre-test and post-test.
After these two sections, you will see the name of the test that was administered to the patient, this will be one of these four: Ex-Only, Full Loop, SVC, or MVV. Next to the test's name, you can see the number of trials in the test, and whether tidal was enabled or disabled.
Under the test's name, you will be seeing the patient's measurements for certain parameters related to performed test mode. Next to these will be the predicted values (both number and percentage), reference info for the predicted values, LLN (lower limit of normal), and z-score.
The section after will be reserved for error codes if any occurred during the testing, in accordance with ATS 2019: Hesitant start, slow start, no plateau, hesitation at maximum volume, incomplete inspiration prior to FVC, low final inspiration, slow filling, obstructed mouthpiece, cough detected, and glottic closure.
After these, you will see session grading, and interpretation and references. The session grading does not refer to how well the results of a patient are but instead refers to the quality (meaning acceptability and usability) of the test. And, the interpretation and references part shows what metric the results were interpreted by, and what reference was used for the predicted values.
The last part of the page is reserved to show graphics, LLN demonstration, and session observations, if any needs to be added. The graphics will show all trials compared to the predicted values. The same thing applies to LLN demonstration as well.
The detailed PDF results, in addition to the parameters above, has these parameters as well: FEV6, FEV3/FVC, FEV6/FVC, MMEF, FEF25, FEF50, FEF75, MET25-75, FEV0.75/FEV6, FEF50/FVC, and BEV, Pef. Rise Time and Hes. Time as additional info (the visual below belongs to the detailed report).
The parameters relevant to the test mode will be measured.
Predicted values can be explained as the measurements a patient would be expected to have and take things like patient's age, gender, etc. These values are calculated using different metrics (Quanjer 2012 (GLI), NHANES III 1999 (Hankinson), ERS 1993 (ECCS, EGKS, Quanjer), Crapo1981, and Knudson 1976). These are predicted references and they can be found by clicking More - Predicted References on the SpiroClinic App.
Per ATS 2019 guidelines, the app may give out these error codes: Hesitant start, slow start, no plateau, hesitation at maximum volume, incomplete inspiration prior to FVC, low final inspiration, slow filling, obstructed mouthpiece. The solutions for these error codes are as follows:
Hesitant start: the patient needs to blast out immediately when their lungs are completely full.
Slow start: the patient needs to blast out immediately when their lungs are completely full.
No plateau: the patient needs to keep going until their lungs are completely empty.
Hesitation at maximum volume: the patient needs to blast out immediately when their lungs are completely full.
Incomplete inspiration prior to FVC: the patient needs to fill their lungs completely before blasting out - meaning taking the deepest breath possible.
Low final inspiration: the patient needs to breathe in back to the top after completely emptying their lungs.
Slow filling: the patient needs to breathe in faster before blasting out.
Obstructed mouthpiece: the mouthpiece must be placed correctly to the device. Also, its fabric must have no damage.
Tests graded A, B, or C are usable, tests graded D are considered suspect, tests graded E might be used by only the interpreter in certain cases, U grade means there is no acceptable maneuver but there is at least one usable maneuver and F-grade tests should not be used at all per ATS 2019 guidelines.
LLN & Z-score
LLN is short for the lower end of normal. Lung function parameters vary according to age, body size, ethnicity and diagnosis, so the normal range must be calculated for the individual as well, in accordance with the predicted parameters of the patient.
For spirometry, only low values are considered to be abnormal, so the lower limit of normal (LLN) is taken to be equal to the 5th percentile of a healthy, non-smoking population.
Z-score is a statistical tool that shows, simply put, how many standard deviations a subject is deviated from its reference value. This helps to understand how out of the normal a patient's results are. If the patient’s results are lower than LLN, this means that their z-score is also below normal.
The graphs on the PDF results will show a number of things: flow-volume, volume-time, best trial, pre-post test comparisons, etc. This helps healthcare professionals to interpret the subject’s lung health.
On the basic report, there will be a comparison of the three trials vs the predicted values, with an emphasis on the best trial. If a post-test was administered, there will be a comparison between the best trials of pre-test, post-test, and predicted values.
The detailed report has the information above as its first page. After these, you will be seeing best 3 trials, and a breakdown of each trial vs. predicted again, divided by pre-test and post-test if one was administered.
- Standardization of Spirometry 2019 Update. American Thoracic Society, 2019.
- How should the lower limit of the normal range be defined? Bruce H. Culver. Respir. Care, 2012.
- The Z-score: A new tool in the interpretation of spirometric data. La Tunisie Medicale, 2017.