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--- resources:pulm:interpreting_pfts [2023/12/20 14:04] – [Assessing Restriction] admin
+++ resources:pulm:interpreting_pfts [2024/03/08 18:32] (current) – [Assessing Restriction] admin
@@ Line 4: / Line 4: @@
 |[[https://goldcopd.org/wp-content/uploads/2016/04/GOLD_Spirometry_2010.pdf | 2010 GOLD Spirometry Guide]]|
 |[[https://doi.org/10.1183/13993003.01499-2021 | 2022 ERS/ATS Interpretive Strategies for PFTs]]|
+====== Interpretation Position ======
+==== Why I use GOLD Criteria ====
+At UMMC, PFTs do report LLN and reference value (pop mean?) but not percentiles or z scores.
+One can back-calculate the SD using $\sigma = \frac{LLN - ref}{-1.65}$ (this assumed LLN on our reports corresponds to 5th percentile).
+Once $\sigma$ is known for the each value (e.g., $\sigma_{FVC} \neq \sigma_{FEV1} \neq \sigma_{RV}$), you could then use $z = \frac{PT_{value} - ref}{\sigma}$ and refer to the tables below to grade severity.
+Given the complexity of this, using ERS/ATS for diagnosing and grading abnormalities is not possible.
+Therefore, I use GOLD criteria.
 ====== Step-by-Step to Interpreting PFTs ======
@@ Line 26: / Line 40: @@
 === GOLD Criteria ===
-^ Grade ^ FEV1 Percent Predicted ^ Severity ^
+[[https://goldcopd.org/wp-content/uploads/2016/04/GOLD_Spirometry_2010.pdf | Source]]
-|1| ≥80%|Mild|
+^ Grade  ^ FEV1 Percent Predicted  ^ Severity     ^
-|2|50% − 79%|Moderate|
+| 1      | ≥80%                    | Mild         |
-|3|30% − 49%|Severe|
+| 2      | 50% − 79%               | Moderate     |
-|4|<30%|Very Severe|
+| 3      | 30% − 49%               | Severe       |
+| 4      | <30% or <50% with CHRF  | Very Severe  |
 ==== Bronchodilator Response ====
@@ Line 46: / Line 61: @@
     - $\Delta FEV1_{volume} >200 mL$
+=== GOLD Definition ===
+  - Required:
+    - $BDR >12%$
+    - $\Delta FEV1_{volume} \geq 200 mL$
+  - Calculation
+    - $ BDR = \frac{FEV1_{postBD} - FEV1_{preBD}}{FEV1_{preBD}}$
+    - **NOTE: this differs from ERS/ATS calculation**
+==== Methacholine Challenge ====
+[[https://doi.org/10.1183/13993003.01526-2016 | Source, ERS 2017]]
+===Response Categorization ===
+{{:resources:pulm:methacholine_response.png?900|}}
+=== Testing Protocol ===
+{{:resources:pulm:methacholine_challenge.png?600|}}
 ===== DLCO Severity=====
+=== ERS / ATS Definition ===
+{{:resources:pulm:ats_dlco.png?600|}}
+[[https://erj.ersjournals.com/content/erj/60/1/2101499.full.pdf | Source]]
+^ Grade  ^ FEV1 z score   ^ Severity  ^
+| NA     | −1.65 to −2.5  | Mild      |
+| NA     | −2.51 to −4.0  | Moderate  |
+| NA     | <−4.1          | Severe    |
+===Gold Definition===
 ^ DLCO Percent Predicted ^ Severity ^
 |>140% | Abnormally High |
@@ Line 64: / Line 106: @@
     - Is $TLC \cdot z_{score}  \leq -1.65$ (//e.g.// < 5th percentile)?
-  * IF not performed, skip to below
+{{:resources:pulm:ats_restriction.png?600|}}
-  * **IFF TLC < 80% or < LLN:**
+[[https://erj.ersjournals.com/content/erj/60/1/2101499.full.pdf | Source]]
+^ Grade  ^ FEV1 z score ^ Severity            ^
+| NA     | −1.65 to −2.5 | Mild                |
+| NA     | −2.51 to −4.0 | Moderate            |
+| NA     | <−4.1 | Severe
+=== GOLD Definition ===
+  - Required:
+    - FVC <80% predicted
-^ TLC Percent Predicted ^ Severity ^
+^TLC Percent Predicted^Severity^
 |>70% | Mild |
 |50%-69% | Moderate |

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