Objective To investigate the changes of pulmonary function and chest X-ray in patients with severe acute respiratory syndrome (SARS) who met the discharge criteria and the factors affecting them. Methods Pulmonary function was measured in 110 cases one day before discharge and in some patients 3 months after discharge, and the most recent chest X-ray before discharge, severity of illness and hospitalization were analyzed. Results Among the 110 SARS patients who met the discharge criteria, 54.5% had residual pulmonary function impairment, with diffusion disorders predominating; 26.4% had abnormal chest radiographs. The proportion of abnormal chest radiographs in the group with residual pulmonary impairment was significantly higher than that in the group with normal pulmonary function (p<0.001); the proportion of patients with severe SARS with residual pulmonary impairment was significantly higher than that of patients with mild to moderate disease, and the degree of pulmonary impairment was more severe; the dose of corticosteroids was not relevant to the incidence and severity of residual pulmonary impairment in this group; pulmonary function recovered significantly after 3 months of discharge, but a few patients still had residual However, a few patients still had mild diffusion impairment. Conclusion Some patients with SARS still had residual lung function impairment and abnormal radiographs at the time of discharge, and the more severe the disease, the more severe the residual lung function impairment, and the lung function recovered significantly 3 months after discharge. Wen Zhongguang, Department of Respiratory Medicine, The First Affiliated Hospital of the Chinese People's Liberation Army General Hospital
Severe acute respiratory syndrome (SARS) is a highly contagious respiratory infectious disease caused by a novel coronavirus, and the pulmonary pathology of SARS patients is similar to acute lung injury (ALI) or ARDS, which can be clinically manifested as different degrees of respiratory failure with a mortality rate of 10-15%. . Some patients still have symptoms such as respiratory distress at the time of discharge and after discharge. In order to understand the status of pulmonary function and whether SARS patients who met the discharge criteria could recover, we measured the pulmonary function of 110 discharged patients and 25 of them 3 months after discharge, and reported as follows.
I. Materials and methods
1. Case selection: 110 patients were hospitalized in the PLA Xiaotangshan SARS designated hospital, including 53 males and 55 females, aged 16-75 years, with an average of 35.7±12.9 years. 3 cases suffered from hypertension (1 of them also suffered from coronary heart disease), 1 case suffered from diabetes mellitus for 9 years, another case had a history of uterine fibroids, and 19 cases were smokers. All cases met the diagnostic criteria for SARS established by the Ministry of Health [1]. Among them, 21 patients with severe SARS met one or more of the following indicators: (1) respiratory rate >30 breaths/min; (2) hypoxemia with arterial partial pressure of oxygen (PaO2) <70 mmHg on oxygen 3-5 L/min , or transcutaneous oxygen saturation (SpO2) <93%, or diagnosed ALI or ARDS; (multilobar lesion or X-ray chest film showing >50% progression of the lesion at 48 hours; (4) shock or multiple organ dysfunction syndrome (MODS); (5) with severe underlying disease, or comorbid other infectious diseases, or age >50 years. The remaining 89 patients who did not meet the criteria for severe SARS were mild to moderate.
2. Hospitalization: 110 patients were hospitalized from 22 to 43 days, with an average of 34.5±5.1 days. All patients were given rest, oxygen, antiviral and supportive treatment during hospitalization. 95 cases were treated with corticosteroids, and were divided into small-dose groups according to the highest daily dose of corticosteroids.
The highest dose of corticosteroids was divided into 48 cases in the small-dose group (£80 mg of methylprednisolone or equivalent doses of other preparations), 30 cases in the medium-dose group (81-160 mg), and 17 cases in the high-dose group (more than 160 mg), with the highest dose of 640 mg/d of methylprednisolone, and the other 15 cases were not treated with steroid hormones. The highest dose of steroid hormone was generally used for 3~5 days, and the dose was gradually reduced after the purpose of treatment was achieved, with a total duration of treatment of 5~43 days (median 13 days). After inpatient treatment with the following 3 conditions at the same time, you can be discharged from the hospital (1) normal body temperature for more than 7 days; (2) significant improvement of respiratory symptoms; (3) significant absorption of inflammatory shadows on X-ray chest film. The results of the latest blood routine and chest frontal and lateral X-ray before discharge were recorded. The former refers to complete absorption of the inflammatory shadow; the latter refers to incomplete absorption of the lesion, with pitting infiltrative shadow in the lung field or increased lung texture, disorganization and blurring, or reticulonodular shadow remaining at the lesion site.
3. Pulmonary function testing: Using the MS-PTF pulmonary function meter manufactured by Jäger, Germany, to determine lung volume (VC), force lung volume (FVC), one-second force lung volume (FEV1.0), one-second rate (FEV1.0/FVC), peak flow rate (PEF), mid-force flow rate (MMEF75/25), total lung volume (TLC), residual air volume (RV), and one-breath method to determine carbon monoxide diffusion. and carbon monoxide dispersion (TLCO SB) were measured in one breath. All measurements were repeated twice, and the highest value was taken. 110 patients underwent pulmonary function testing 1 day before discharge, and 25 of the 60 patients with residual pulmonary impairment underwent pulmonary function review 3 months after discharge. Pulmonary function results were expressed as % actual/expected values, and <80% was judged as abnormal. Among them, 79-70% were mild impairment, 69-50% were moderate impairment, and <50% were severe impairment. Based on the measurements, the type of pulmonary impairment was distinguished as simple diffusion dysfunction (reduced TLCO), restrictive, obstructive, or mixed ventilation impairment.
To prevent possible nosocomial infections, operators were provided with personal protection according to the standards for exposure to SARS patients, the testing room was ventilated with open windows, and the air and floor were disinfected daily with 0.5% peroxyacetic acid.
II. Results
1. Results of pulmonary function measurement of SARS patients at discharge: Among 110 SARS patients discharged from the hospital, 60 still had significant pulmonary function impairment, accounting for 54.5% of the number of pulmonary function measurements (see Table 1). 60 patients with pulmonary function had a VC of 3.18±0.69, accounting for 86.12±17.84% of the expected value; FEV1.0 was 2.65±0.64, accounting for 83.45±15.65% of the expected value 83.45±15.65%; FEV1.0/FVC 87.69±7.50; TLC 5.52±0.96, 83.45±14.17% of the expected value; TLCO SB 5.85±1.02, 64.46±9.46% of the expected value. The types of pulmonary impairment were simple diffusion disorder in 49 cases (44.5%); diffusion disorder combined with restrictive ventilation disorder in 7 cases (6.4%); diffusion disorder combined with mixed ventilation disorder in 2 cases (1.8%); and diffusion disorder combined with obstructive ventilation disorder and simple restrictive ventilation disorder in 1 case each (0.9%). The numbers of cases with mild, moderate and severe pulmonary dysfunction were 23 (20.9%), 28 (25.5%) and 9 (8.2%), respectively.
Table 1 Degree and type of pulmonary impairment in patients discharged from SARS
Type of pulmonary impairment Mild Moderate Severe Total
Diffusion impairment 19 22 8 49
Diffusion impairment + restrictive ventilation impairment 2 4 1 7
Diffusion disorder + obstructive ventilation disorder 1 1
Diffusion disorder + mixed ventilation disorder 1 1 2
Restrictive ventilation disorder 1 1
Total 23 28 9 60
2. Relationship between chest X-ray and pulmonary function: 81 cases (73.6%) of 110 SARS patients with normal and 29 cases (26.4%) of abnormal chest X-ray were determined before discharge from hospital. Among the 60 cases with residual pulmonary function impairment, 28 cases had abnormal chest radiographs, and only 1 case had abnormal chest radiographs among patients with normal pulmonary function (see Table 2). The proportion of abnormal chest radiographs was significantly higher in the group with residual pulmonary impairment than in the group with normal pulmonary function.
Table 2 Comparison of pulmonary function and chest radiographs in patients discharged from SARS
SARS discharged patients Number of cases Chest film abnormal (%) Chest film normal (%)
Pulmonary function impairment group 60 28 (46.7)* 32 (53.3)
Normal lung function group 50 1 (2) 49 (98)
*X2=6.019, P<0.025 compared with the normal lung function group
3. Relationship between severity of illness and pulmonary function: 90.5% (19/21) of 21 patients with severe SARS had significant pulmonary function impairment at discharge. Among them, 7 cases had severe diffusion impairment, 1 case had severe diffusion impairment combined with moderate restrictive ventilation dysfunction, 3 cases had moderate diffusion impairment combined with restrictive ventilation dysfunction, and 8 cases had moderate diffusion impairment. Legacy pulmonary impairment was found in 46.1% (41/89) of the mild to moderate patients. The proportion of severe SARS patients with pulmonary impairment at discharge was significantly higher than that of mild to moderate patients (p<0.001) and the impairment was more severe (Table 3).
Table 3, Relationship between pulmonary function impairment and severity of disease in SARS patients at hospital discharge
Severity of illness Severe pulmonary impairment (%) Moderate pulmonary impairment (%) Mild pulmonary impairment (%) Total (%)
Severely ill patients 8 (42.1) 11 (57.9) 0 19 (90.5)*
Mild to moderate patients 1 (2.4) 17 (41.5) 23 (56.1) 41 (46.1)
Total 9 (15.0) 28 (46.7) 23 (38.3) 60 (54.5)
*X2=13.5, P<0.001 compared with mild to moderate patients
4. relationship between corticosteroid treatment and impairment of pulmonary function: as shown in Table 4, there was no significant difference in the incidence and extent of impairment of pulmonary function at discharge between the SARS groups in the small, medium and large dose groups of corticosteroids, and the impairment of pulmonary function in the group without corticosteroids was significantly lower than that in the group with corticosteroids.
Table 4 Relationship between pulmonary function impairment and steroid hormone treatment dose at discharge in SARS patients
Degree of impairment Number of cases Mild impairment (%) Moderate impairment (%) Severe impairment (%) Total (%)
No hormone group 15 2 (13.3) 0 0 2 (13.3)*
Hormone group 95 21 (22.1) 28 (29.5) 9 (9.5) 58 (61)
Low dose group 48 10 (20.8) 14 (29.2) 4 (8.3) 28 (58.3) D
Medium dose group 30 7 (23.3) 9 (30) 3 (10.0) 19 (63.3) D
High-dose group 17 4 (23.5) 5 (29.4) 2 (11.8) 11 (64.7) D
Total 110 23 (20.9) 28 (25.5) 9 (8.2) 60 (54.5)
*X2=7.22, p<0.001 compared with the hormone group; DX2=8.553, p>0.05 compared with the large, medium and small dose groups
5. Results of pulmonary function review in 25 SARS patients: among 60 patients with residual pulmonary impairment, 25 had significant improvement in pulmonary function review after 3 months (see Table 5), but diffusion function was still below normal in a few patients.
Table 5, results of pulmonary function review in 25 SARS patients
Subgroup
VC (% expected value)
TLC(% expected)
FEV1.0(% expected value)
TLCOSB(%predicted)
At discharge
3 months after discharge
3.19±0.75L
(87.8±20.1)
3.47±0.71L
(93.6±13.3)
4.51±0.85L
(83.7±14.3)
5.28±0.89L
(97.1±9.04
2.58±0.54L
(85.18±18.0)
2.80±0.61L
(91.2±15.5)
5.72±1.34L
(62.9±13.5)
5.72±1.52L
(84.57±9.0)
P-value
0.01698
0.00408
0.02064
0.000343
III. Discussion
It is well documented that the pulmonary lesions caused by SARS are significantly different from those of general pneumonia. Autopsy data confirm that the pulmonary pathological changes in SARS patients are acute leaking inflammation of the interstitial lung, similar to those of ALI or ARDS, with extensive hyaline membrane formation, neutrophil reduction in lung tissue, interstitial thickening, alveolar type II cell proliferation and exfoliation, and subepithelial and interalveolar fibroblast hyperplasia [3]. Pulmonary shadow absorption is slow to improve [4], and approximately 20% of patients are critically ill, with a significantly higher morbidity and mortality rate compared to general pneumonia.
We measured the pulmonary function of 110 SARS patients who met the discharge criteria, and the results confirmed that 54.5% of the patients still had residual pulmonary impairment, of which diffusion impairment was predominant, with some patients exhibiting moderate or severe diffusion impairment and a small number of patients with concomitant restrictive ventilation dysfunction. Although there was no data on pulmonary function before the disease, only one patient had diabetes mellitus according to the medical history, which may have had pulmonary diffusion impairment; 19 patients had a history of smoking, but smoking caused more pulmonary ventilation impairment; the remaining patients had no history of diseases affecting pulmonary function. Therefore, it is presumed that the impairment of pulmonary function in this group of patients is related to the pulmonary lesions caused by SARS. extensive inflammatory exudate, interstitial thickening, alveolar type II cell hyperplasia, and subepithelial and interalveolar fibroblast hyperplasia in the lungs of SARS patients are the pathological basis of diffuse and restrictive ventilation barrier carcinoma. Of the 60 patients with residual pulmonary impairment, 28 (46.7%) were associated with abnormal X-ray chest radiographs, also indicating that SARS patients with discharge criteria still had residual intrapulmonary exudate or/and pulmonary fibrosis. Whether these residual lesions can be absorbed and dissipated in the future is subject to subsequent follow-up of pulmonary function and pulmonary imaging changes. In addition, among the 81 patients with normal chest radiographs, 32 (39.5%) still had abnormal lung function, indicating that lung function indicators are more sensitive than chest radiographs in observing residual lung lesions and are more worthy of follow-up to evaluate the prognosis of SARS patients.
The residual pulmonary function impairment of severe SARS patients at discharge is more severe than that of general patients, which is related to the severe pulmonary lesions and poorer treatment outcome of severe patients. How to improve the outcome of such patients and reduce the residual lung lesions is a topic for future research. The correct use of steroids during the immune hyperactive phase and the pulmonary destruction phase can help reduce lung damage, reduce the incidence of respiratory failure and improve the cure rate [2]. The lung function impairment left in this group of patients at discharge was not related to the steroid hormone dose, probably because the purpose of steroid hormone treatment in this group of patients was different, some were to reduce the symptoms of toxicity and some were to reduce intrapulmonary exudation; the time of starting treatment and the duration of treatment were also different; the patients with severe SARS were mostly treated with high-dose steroid hormones, and these patients had serious lung lesions that were not easily absorbed and dissipated in a short period of time. In addition, the low dose of corticosteroids and the short duration of treatment in this group of patients is another reason why there is no difference in residual pulmonary function impairment among the three groups of patients. patients with SARS continued to absorb and improve their pulmonary lesions after discharge from the hospital, and most of their pulmonary function had returned to normal after 3 months, with only a few remaining with mild diffusion impairment.