Towards Spirometry Excellence: Part 1
In the last newsletter the need for a “Standard Operating Procedure” (SOP) manual was discussed. This statement details the contents of a useable SOP:
1. Prescreening Questions
These questions must be asked by the technician prior to performing the spirometry test and is meant to identify any conditions that might be present that would falsely elevate or depress the spirometry test measurements, thereby leading to a false positive or negative.
2. Respiratory Symptom Questionnaire
When subjects present at a clinic with respiratory complaints, specific symptoms need to be elicited and organized in such a way that the over reading physician has key information that explains the spirometry results. Symptoms of cough, phlegm production, and minor wheezing occur early in the course of COPD, and are non specific symptoms that are often of no concern to the subject. The most important symptom from the subject’s point of view is dyspnea on exertion (Mayo Airflow Update Vol 2, No 2 1984)
Symptoms can point to specific lung diseases such a chronic bronchitis, emphysema, 1 asthma, or occupationally related restrictive lung diseases such as asbestosis or silicosis. The instrument of choice is the American Thoracic Society Questionnaire or the OSHA medical questionnaire. This questionnaire can be filled out in advance of the clinic visit and given to the spirometry technician at the time of testing.
The Prescreening Questionnaire and the Respiratory Symptom Questionnaire can be found in the course manual of those personnel who have completed the NIOSH Spirometry Training Course.
3. Blood Pressure
Because the spirometric test increases intro-thoracic pressures which can aggravate existing cardio vascular conditions such as hypertension, the clinic Medical Director should set a Blood Pressure threshold. When exceeded, the technician clears with the attending physician before proceeding with the test (AARC Spirometry 1995 Update).
Towards Spirometry Excellence: Part 2
In the last newsletter we looked at the first three components of a spirometry Standard Operating Procedures manual (SOP). These included the Prescreening Questionnaire, the Respiratory Symptom Questionnaire, and the criteria for a prescreening Blood Pressure measurement. Besides these, there are ten other components required for a complete SOP.
- A list of the key measurements that the medical director would want to see, along with their definitions. For example, the commonly used measurements are the Forced Vital Capacity (FVC), the Forced Expiratory Volume at one second (FEV1), the flow rate in the middle 50% of the FVC (FEF25-75%), the Peak Flow Rate (PFR), and the % FEV1 (ratio of FEV1/FVC).
- A list of the contraindications that the operator and physician should look for:
Due to increases in myocardial demand or changes in blood pressure:
– Acute myocardial infarction within 1 wk
– Systemic hypotension or severe hypertension Significant atrial/ventricular arrhythmia Noncompensated heart failure
– Uncontrolled pulmonary hypertension
– Acute cor pulmonale
– Clinically unstable pulmonary embolism
– History of syncope related to forced expiration/cough
Due to increases in intracranial/intraocular pressure:
– Cerebral aneurysm
– Brain surgery within 4 wk
– Recent concussion with continuing symptoms
– Eye surgery within 1 wk
Due to increases in sinus and middle ear pressures:
– Sinus surgery or middle ear surgery or infection within 1 wk
Due to increases in intrathoracic and intraabdominal pressure:
– Presence of pneumothorax
– Thoracic surgery within 4 wk
– Abdominal surgery within 4 wk
– Late-term pregnancy
Infection control issues:
– Active or suspected transmissible respiratory or systemic infection, including tuberculosis
– Physical conditions predisposing to transmission of infections, such as hemoptysis,
- Hazards of performing spirometry: dizziness or syncope, chest or back pain, coughing,and bronchospasm.
- Spirometer calibration procedures: these should be detailed depending on whether or not a volume or flow spirometer is used. Procedures for each type of spirometer differ, but must be performed with the periodicity as stated by the OSHA enforced ATS/ERS Standard. This section would include the archiving of records and trouble shooting when calibration falls outside established limits.
- Spirometry program setup steps:
- Establish whether or not the test will be done in the sitting or standing position. Sitting may be safer should a subject faint; however, FEV1 values are smaller in the sitting position. Whether sitting or standing, there are established exceptions to the rule which must be documented and followed.
- Setup should also establish procedures to follow accepted conventions to round height measurements up or down in a manner which prevents bias.
- Setup calls for appropriate selection of prediction equations to calculate percent of predicted value. Currently ATS and ACOEM recommend the NHANES III equations.
- Select which size graphs you want for the printout, large (Validations size) or small (Diagnostic size). The generally accepted rule is that if the spirometer is a hand held unit with limited record storage, use large size graphs since these are required for all SSA disability exams and all legal cases. Computer driven spirometers can generate graphs in either size on demand, so graph size is optional.
The remaining six components of an SOP will be discussed in the next newsletter.
Towards Spirometry Excellence. Part 3
In the previous newsletters we have discussed seven of 13 components of a complete Standard Operations Procedure Manual (SOP). The following one of six remaining components is given.
4. Test Procedure and Instructions
Spirometry testing is simple but fraught with technical pitfalls that can invalidate the pulmonary function measurements. Failure to obtain full understanding, cooperation and effort from a subject during any part of the test usually results in an underestimation of the true pulmonary function. Poorly maintained spirometers also affect the accuracy of observed spirometric values. Such erroneous measurements may cause a normal, healthy subject to be mislabeled as impaired or lead to incorrect assessment of impaired subjects.
In occupational medicine, the consequences of such misinterpretations can go beyond simply making an inaccurate diagnosis. Decisions regarding fitness for duty, workplace accommodation, and compensation for work-related illness may also be affected. Furthermore, since occupational spirometry tests are often conducted in the regulatory and medical-legal arenas, the validity of the spirometry test is likely to be scrutinized. Therefore, it is critical for both clinical and administrative purposes that occupational medicine physicians understand the need for standardization in performing the test.
(ACOEM Spirometry Position Paper, 2000)
A full understanding of what needs to be conveyed to the subject is vital to achieve the maximum response. A maximal inhalation is rapidly taken from room air before placing the mouthpiece in the mouth. Prompt the inhalation with statements such as “Take a deep breath. More, more. All you can hold.” Then prompt the exhalation with: “Now BLAST out hard and fast!” Continue by saying “PUSH, PUSH!” The technician should be a cheerleader with constant, enthusiastic coaching. You need not shout, but have intensity in your voice and good body language.
To insure that test instructions are fully understood, the elements of the instruction are given in six steps.
- Establish rapport.
- Gather pre-test data: Pre-screen questionnaire, B.P., height, BMI.
- Briefly explain test and mouthpiece position.
- Demonstrate mouthpiece position and have test subject demonstrate proper mouthpiece placement. Demonstrate maneuver with maximal effort blast.
- Administer test: Chin up and chair behind if standing, torso upright, mouthpiece off to one side, actively coach to full inspiration and full expiration.
- Look for acceptability and repeatability. (See component 6 in next newsletter)
The test can be repeated up to eight times in order to achieve three acceptable trials, of which the two best FVC and FEV1 values are within 150ml.
In the next newsletter Quality Control requirements will be discussed as well as the remaining elements of the SOP.