In this topic, an overview on (special) patient categories is given and which other/extra procedures might be indicated when performing spirometry for these patient categories.
| Children | A smaller chair or a raised footstool should be provided for children. With appropriate coaching, children as young as 2.5 years old with normal cognitive and neuromotor function can perform acceptable spirometry. More than 8 attempts may be required because each attempt may not be a full maneuver. Children may benefit from practicing the different phases of the maneuver before attempting a full maneuver. Even if unsuccessful at the first session, children will learn to be less intimidated, and their performance may improve in subsequent sessions. The operators who are involved in the pulmonary function testing of young children should be specifically trained and competent to work with this population. A child-friendly environment is important for successful testing. Encouragement, detailed but simple instructions, lack of intimidation, and visual feedback in the teaching are important in helping children to perform the maneuver. Operators should be aware of the child's enthusiasm and effort to avoid exhausting or discouraging the child from future testing. |
| Elderly & mental retardation | Operators should be aware of the patient's level of comprehension. When this is impaired, encouragement and instructions should be detailed but simple. Visual feedback can be helpful to perform the maneuver. In certain diseases, performance may deviate from the expected flow volume curve. The operator must have the ability to override automatic exclusion by the software. |
| Wheelchair bound or bedridden patients | If testing is undertaken with the patient in another position, this must be documented in the report. |
| Pregnant women | Pregnancy has minor effects on spirometric indices. The total lung capacity and the VC remain unchanged, but the FRC decreases by 10-25%. This may lead to airway closure in the normal tidal breathing range. Spirometry in late term pregnancy may be contraindicated due to increased intraabdominal pressures. |
Patients with (upper airway obstruction or) neuromuscular disease are often unable to initiate a rapid increase in flow, and the BEV limit may be exceeded. The operator must have the ability to override the BEV acceptability designation for such patients.
Patients with extrathoracic obstruction are often unable to reach high inspiratory flow. Abnormal inspiratory flow volume curve is observed in patients with extrathoracic obstruction. In case of a fixed obstruction also expiratory peak flow may be lower than expected.
Patients with vocal cord paralysis may have lower inspiratory and expiratory flows.
Measurements preferably scheduled at the beginning of the workday.
Extra precautions should be taken for patients with, or suspected of having, tuberculosis, hemoptysis, oral lesions, or other known transmissible infectious diseases. Possible precautions include reserving equipment for the sole purpose of testing infected patients or testing such patients at the end of the workday to allow time for spirometer disassembly and disinfection and/or testing patients in their own rooms with adequate ventilation and appropriate protection for the operator. Tissues or paper towels should be offered to help patients deal with secretions [1].
Patients unable to use a mouthpiece may be able to use a face mask [2]. In some circumstances, such as patients with tracheostomy or nasal resection, noninvasive adjustments such as a sealing face mask, tubing connectors, or occlusion valves can be applied at the discretion of the operator and must be recorded in the operator notes [1].
Well-fitting dentures are usually left in place. A 2001 study found that spirometry results are generally better with dentures in place, but a larger 2018 study found that FVC was an average of 0.080 L higher when dentures were removed [1].
For patients who are unable to stand upright or have a deformity of the thoracic cage, such as kyphoscoliosis, height can be estimated using ulna length, which is preferred in children [3] or arm span [4].
Arm span should be measured with the subject standing against a wall with the arms stretched to attain the maximal distance between the tips of the middle fingers. A regression equation [67.904868 + 0.664182 × Arm span (cm) - 2.816175 × Sex - 4.05492 × Race - 0.070892 × Age (yrs); Sex (1 male; 2 female), Race (1 White; 2 Black)] using arm span, race, sex and age has been found to account for 87% of the variance in standing height, with the standard error of the estimate for height ranging from 3.0 to 3.7 cm. Using fixed arm-span ratios (e.g. height-arm span/1.06) estimated the standing height reasonably well, except at the extremes, but was always inferior to the regression equation. Estimating height in this way introduces a further level of uncertainty with regard to the predicted value of the lung function index, and the use of fixed ratios has been shown to lead to misclassification of disease. All-age relationship between arm span and height in different ethnic groups [5].
It's important to consider variations based on sex, age, and ethnicity when using these methods. In individuals for whom arm span measurement is challenging, knee height may serve as a practical alternative to predict height [5].
Birth sex and ethnicity should be included in the patient information on the spirometry request. Otherwise, the operator will ask the patient to provide this information. When requesting birth sex data, patients should be given the opportunity to provide their gender identity as well and should be informed that although their gender identity is respected, it is birth sex and not gender that is the determinant of predicted lung size. Inaccurate entry of birth sex may lead to incorrect diagnosis and treatment. Similarly, patients should be informed of the need for reporting ethnicity (Braun L et al. Eur Respir J 2013; 41:1362-1370).