Value of Exhaled Nitric Oxide (FeNO) And Eosinophilia During the Exacerbations of Chronic Obstructive Pulmonary Disease Requiring Hospital Admission

Figures & data

Table 1. General characteristics of the study population, including clinical, analytical and functional variables.

Patients ( n)	50
Age	75 ± 6 years
Sex, males (%)	45 (92%)
Weight (kg)	73.4 [66–83]
BMI (kg/m^2)	27 [25–31]
Active smoker	5 (11%)
Pack-years	49 [35–60]
COPD GOLD 1 (mild)	1 (2%)
COPD GOLD 2 (moderate)	15 (30%)
COPD GOLD 3-4 (severe)	34 (68%)
Chronic inhaled GC	39 (79%)
Systemic GC prior to FeNO	29 (58%)
GC dose (mg)	40 [40–60]
LABA	45 (90%)
LAMA	44 (88%)
C-reactive protein mg/L	26 [9–101]
Leukocytes cells/mm^3	11,560 [7,682–14,370]
Eosinophils cells/mm^3	200 [107–280]
FeNO (ppb)	25 [17–39]
Eosinophil cationic protein (ECP) mcg/L	21 [12–49]
Procalcitonin (ng/mL)	0.12 [0.06–0.21]
IgE (IU/mL)	62 [26–228]
FEV1 (L) FEV1 (%)	1.150 [0.850–1440] 48 [36–62]
FVC (L) FVC (%)	2.675 [2.272–3.020] 86 [75–97]
pO2 mmHg	56 [50–61]
pCO2 mmHg	43 [35–48]
Mean hospital stay (days)	4.9 [2–7]

BMI, body mass index; GC: glucocorticoids; LABA, long acting beta2 agonist; LAMA, long acting muscarinic antagonist; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity.

Figure 1. FeNO levels at different moments of determination.

*Differences with p < 0.001 between emergency room and stable phase.

Figure 2. Correlation of FeNO levels with eosinophilia in peripheral blood in the emergency room (ER).

Figure 3. Correlation of FeNO levels with eosinophilia in peripheral blood at discharge (D).

Figure 4. Distribution of FeNO levels according to clinical phenotypes (chronic bronchitis, emphysema, ACOS).

Table 2. FeNO levels, eosinophils and mean hospital stay of COPD exacerbations according to clinical phenotype.

	Chronic bronchitis n = 21 (40%)	Emphysema n = 16 (32%)	ACOS n = 13 (26%)	p
Exacerbators n (% phenotype)	6 (29%)	6 (38%)	8 (62%)	0.41
FeNO, emergency room (SD) ppb	23 (10)	27(16)	73 (57)	<0.0001
FeNO, discharge ppb	15 (10)	15 (7)	36 (29)	0.01
FeNO, stable Ppb	18 (13)	24 (12)	34 (24)	0.026
Eosinophils, emergency room cells/mm^3	184 (109)	159 (103)	508 (515)	0.002
Eosinophils %, emergency room	2.1	2.0 (2)	4.8(4.7)	0.02
Eosinophils, discharge cells/mm^3	113 (100)	56 (53)	117 (132)	0.3
Eosinophils %, discharge	1.5 (1.2)	0.6 (0.3)	1.3 (1.7)	0.25
Mean hospitalization (days)	5.4 (3.2)	4.6 (2)	4.5 (3.2)	0.69

Table 3. Values of the variables studied according to cut-off points of P50 (25 ppb) for FeNO and 2% eosinophils.

	FeNO <25 ppb	FeNO ≥25 ppb	p	Eosinophils <2%	Eosinophils ≥2%	p
Eosinophils (cells/mm^3)	174	340	0.05	128	428	0.01
Eosinophils %	2	3.5	0.01	–	–
FeNO	–	–		31	46	0.1
ECP mcg/L	33	37	0.6	33	36	0.9
IgE IU/mL	279	253	0.9	356	152	0.3
CRP mg/L	62	51	0.5	72	36	0.03
PCT ng/mL	0.12	0.27	0.03	0.26	0.13	0.05
pCO2 mmHg	42	44	0.5	44	55	0.4
pO2 mmHg	57	56	0.6	56	58	0.5
FEV1 (L)	1.01	1.22	0.04	1.08	1.19	0.4
FEV1 (% predicted)	47	52	0.02	48	52	0.3
BMI kg/m^2	28	29	0.8	29	27	0.3
Hospitalizations prior year	1.5	1.2	0.6	2.18	2.14	0.9
Mean hospital stay (days)	3.4	3	0.6	5.17	4.5	0.5

ECP, eosinophil cationic protein; CRP, C-reactive protein; PCT, procalcitonin; BMI, body mass index; FEV1, forced expiratory volume in 1 second; FVC, forced vital capacity.

Figure 5. ROC curves: FeNO and eosinophil levels in the ER, at the start of the exacerbation, in correlation with the existence of the ACOS phenotype.