How Local SARS-CoV-2 Prevalence Shapes Pulmonary Function Testing Laboratory Protocols and Practices During the COVID-19 Pandemic

To the Editor:

In March 2020, the World Health Organization declared COVID-19 a global pandemic.¹ Initially, hospitals canceled numerous elective and outpatient medical services, including nonurgent pulmonary function tests (PFTs).² Gradually, these services were resumed in accordance with national guidelines.³ Organizations including the American Thoracic Society (ATS) and others^{4 , 5} have since published recommendations regarding provision of respiratory services in the era of COVID-19. We aimed to evaluate which practices were being most widely adopted by PFT laboratories across the United States and to examine how community COVID-19 prevalence shaped those practices.

Methods

In August 2020, we invited all members of the ATS PFT Laboratory Registry to complete an online survey, and we asked the American Association for Respiratory Care to post an invitation to members of the American Association for Respiratory Care Diagnostics Section. The questionnaire collected information on how PFT laboratories were responding to the COVID-19 pandemic including the following: demographics including local COVID-19 prevalence according to the Centers for Disease Control and Prevention coronavirus map,⁶ clinical utility and aerosol-generating potential (AGP) of specific PFTs, infection prevention, patient screening protocols, and laboratory functional status. We assessed associations by contingency analysis, with χ² P < .05 indicating statistical significance (JMP Pro 15; SAS Institute Inc). The study did not require institutional review board review because it was considered a quality-related investigation.

Results

Respondents completed the survey between August 17 and October 31, 2020. From the ATS Registry, the response rate was 41%. Most of the 132 respondents indicated their clinical role as laboratory manager (48.8%) or PFT technology staff (35.1%). Most laboratories were in community and academic hospitals. Most laboratories were small (63%) and medium (31%) sized (Table 1 ). Most academic laboratories were medium or large, whereas community, private, and other laboratories were primarily small (P < .01). Fifty-one percent of laboratories were located in low COVID-19 prevalence areas, 28% in medium prevalence areas, and 21% in high prevalence areas. The results of the survey categorized by local prevalence of COVID-19 are shown in Table 1.

Table 1.

Summary of Survey Responses by Local COVID-19 Prevalence (Cases per 100,000)

Survey Item	Low Prevalence (< 5,000)	Medium Prevalence (5,000-20,000)	High Prevalence (> 20,000)
Laboratory type (% of responses)
Community	61	31	21
Academic	26	40	57
Private/other	13	29	21
Laboratory size (% of responses)
Small (< 20 tests per day)	73	57	43
Medium (20-50 tests per day)	24	37	43
Large (> 50 tests per day)	3	6	14
PFT classification (% of responses)
PFT considered high AGP	88	69	82
PFT not considered high AGP	12	31	18
PPE practices (% utilization)
Patient mask	94	94	93
Provider mask	100	97	93
Surgical mask	66	69	61
N95	87	81	82
PAPR	19	17	21
Face shield	94	94	96
Gown	70	75	79
Gloves	84	89	82
Hat	19	17	7
Shoe covers	4	3	0
Disinfection practices (% utilization)
Disinfect equipment and surface between patients	100	100	100
In-line antimicrobial filter	93	89	93
Change flow sensor between patients	28	28	25
Mean air exchange time, min	33	24	32
HEPA filter in at least some rooms	31	47	39
UV sanitization in at least some rooms	15	25	14
Negative pressure in at least some rooms	40	33	29
Waiting room precautions	96	92	96
Patient hand hygiene available	84	78	75
Patient screening practices (% utilization)
Symptoms screening	97	100	96
Temperature screening	88	92	89
SARS-CoV-2 PCR test requireda	51	39	74a
Mean wait time if previous positive COVID-19 test, d	20	22	21
Operational status (% of responses)
Fully operational	75	69	64
Partially operational	25	31	32
Fully closed	0	0	4

AGP = aerosol generating potential; HEPA = high-efficiency particulate air; PAPR = powered air-purifying respirator; PCR = polymerase chain reaction; PFT = pulmonary function test; PPE = personal protective equipment; UV = ultraviolet.

^aP = .02 for positive testing relative to low and medium prevalence groups.

Respondents indicated that they thought spirometry and diffusing capacity of the lung for carbon monoxide had the highest utility for patient care (Fig 1 ). Most laboratories (82%) reported that most PFTs were considered by their institution to be high AGP (Fig 1), with no differences between types of laboratories (P = .34). Several respondents commented that they were working to convince their administration that PFTs should be considered high AGP.

Figure 1.

Mean rating of AGP and clinical utility of common pulmonary function tests. Procedures were rated individually based on subjective measures using a numerical interval scale (1 = low, 2 = medium, 3 = high). AGP = aerosol-generating potential; CPET = cardiopulmonary exercise testing; Dlco = diffusing capacity of the lung for carbon monoxide; Feno = fractional exhaled nitric oxide; MDI = metered-dose inhaler; MIP/MEP = maximal inspiratory pressure/maximal expiratory pressure; Neb = nebulizer.

With respect to personal protective equipment, 98% of laboratories required that staff wear a facemask during PFTs, and that patients wear one except during testing. There were no differences between the use of N95 respirators and local COVID-19 prevalence (P = .22), with 84% of laboratories using N95 respirators for at least some procedures. In addition to masks, 95% of laboratories used eye protection, 85% used gloves, and 70% used protective gowns during PFTs.

All laboratories disinfected surfaces and equipment in PFT rooms between patients, and 83% provided time for air exchange, with a mean duration ± SD of 31 ± 28 min. Almost all laboratories (92%) reported using in-line antimicrobial filters in PFT equipment. Additionally, 95% of laboratories implemented waiting room precautions (eg, physical distancing, mask-wearing policies, hand hygiene). We found that high-efficiency particulate air filters and negative pressure systems were used to similar extents (37% and 36%, respectively), both being more common than ultraviolet sanitization (17%). No significant variation was observed among room and equipment disinfection protocols based on local prevalence of COVID-19.

Screening for symptoms of COVID-19 and temperature checks prior to PFT appointments were implemented at rates of 99% and 96%, respectively. Testing for SARS-CoV-2 by polymerase chain reaction (PCR) was adopted by 54% of laboratories, of which 58% required patients to have a negative test result within 5 days of their appointment. We also found that implementation of PCR testing differed significantly between high prevalence areas (74%) and low or medium prevalence areas (51% and 39%, respectively) (P = .02). For patients with a positive COVID-19 diagnosis, 41% of laboratories required a period of at least 14 days symptom-free prior to testing, and 43% required a period of at least 30 days. Only 9% of laboratories indicated wait times of ≤ 10 days.

Pulmonary services had largely been restored by the close of the survey, with 71% of laboratories reporting as fully operational, 28% as partially operational, and 1% as fully closed. Many respondents commented that testing volume was markedly reduced because of cleaning protocols required to maintain a safe testing environment. The number of laboratories conducting various tests during the survey period is illustrated in Figure 2 . Only 70% of laboratories were conducting spirometry, which suggests that concern over the high AGP of spirometry was influencing laboratories not to perform it despite its high clinical utility.

Figure 2.

Distribution of procedures being conducted by laboratories at the time of survey. (n = 85 because of missing data). CPET = cardiopulmonary exercise testing; Dlco = diffusing capacity of the lung for carbon monoxide; Feno = fractional exhaled nitric oxide; MDI = metered-dose inhaler; MIP/MEP = maximal inspiratory pressure/maximal expiratory pressure; Neb = nebulizer.

Discussion

Our survey has demonstrated that PFT laboratories have acted in accordance with ATS⁴ or European Respiratory Society⁵ recommendations. Common practices include implementation of physical distancing and mask-wearing in common spaces, easy access to hand hygiene, appropriate personal protective equipment usage by staff, thorough disinfection of equipment and surfaces, and patient screening protocols for fever and other COVID-19 symptoms. Most laboratories’ institutional policies considered PFTs collectively to be high AGP, in line with recent evidence.^{7 , 8}

Implementation of some practices varied depending on local prevalence, whereas others did not. For example, PCR testing was more likely to be adopted in high prevalence areas in comparison with low or medium prevalence areas, whereas N95 respirator usage among laboratories was relatively uniform. Some more resource-intensive measures were used to a lesser degree independent of prevalence. Despite all these challenges, nearly three-quarters of laboratories in our sample were fully operational. We acknowledge important limitations to these results, which include small sample size, estimated to be < 5% of all PFT laboratories, the timing of the survey, incomplete responses for Figure 2 data, and that nonoperational laboratories or those following less stringent protective measures may not have responded. Nevertheless, these results demonstrate the resilience and adaptability necessary to cope with the ever-changing demands of safely providing respiratory care during the COVID-19 pandemic.