Hypoxemia and not hyperoxemia predicts worse outcome in severe COPD exacerbations - an observational study

Figures & data

Table 1. Patient characteristics; demographic data, clinical exposures and total number of events.

Total number of patients	289
Female	191
Age, median, IQR	74.8 [69.6–81.8]
*Forced Expiratory Volume in 1 sec % of expected volume, mean, SD	38.5 (17)
*Forced Expiratory Volume in 1 sec. in L, mean, SD	0.88 (0.46)
Admission days, median, IQR	4.8 [3.0–8.4]
**Number of patients with >1 admission within the past year	219
Number of patients with >10 days of admission	54
Number of patients with ≤10 days of admission	235
<4 days alive and out of hospital 14 days from admission	83
<10 days alive and out of hospital 30 days from admission	51
Receiving Long Term Oxygen Therapy	101
Oxygen delivery in L/min, mean, SD	2.7 (3.1)
Long term Non-Invasive-Ventilation	17
>1 administration of opioid/ 24 hours	122
>1 administration of BZD/ 24 hours	91
>1 administration of opioids and BZD/ 24 hours	46
>1 administration of opioids or BZD/ 24 hours	167
Never SpO2 in the range 88–92%	94
1 measurement of SpO2 in the range 88–92%	69
2 measurements of SpO2 in the range 88–92%	93
Perfect controlled oxygen administration.	35
***‘Hypoxemic ever’	48
1 Hypoxemic episode	36
2 Hypoxemic episodes	11
3 Hypoxemic episodes	1
***‘Hyperoxemic ever’	232
Acute non invasive ventilation	105
Admitted in ICU	13
Received invasive ventilation	2
Dead after 24 hours, but within 30 days	52

*All lung function tests included were taken within a year before admission

**COPD exacerbation related-admissions

***Total number exceeds number of patients, since some patients experienced both hypoxemic and hyperoxemic episodes. This group contributed to the data in both the ‘hypoxemic ever’ and the ‘hyperoxemic ever’ group. However, because of low numbers, we did not consider this overlap to have any statistical nor clinical impact.

Figure 1. Shows patient flow from screening, to inclusion and through first 24 hours treatment and into Days Alive and Out of Hospital up until 30 days from admission (DAOH-30). The flowchart illustrates the composites of ‘Treatment failure’ and ‘late hypercapnic respiratory failure’ by showing a) the number of events within first 24 hours of treatment, B) number of events after 24 hours of treatment given by numbers (%); ‘treatment failure’ 132 (45.6%) and ‘late hypercapnic respiratory failure’ 28(9%) and C) total number of events.

Figure 2. Forest plot showing risks of exposures as Odds Ratios [95% Confindence Intervals] in relation to low numbers of days alive and out of hospital within 14 days and treatment failure.

Table 2. Associations between exposures and outcomes NB: Only powered for the oxygenation variables (marked with #).

Associations between exposure variables and less than 4 Days Alive and Out of Hospital within 14 days from admission (DAOH-14 < 4)
Variables	Multivariate OR (95%)	P value
Hyperoxemic ever#	1.0 (0.5–2.1)	0.9
Hypoxemic ever#	2.4 (1.2–4.8)	0.02
Opioids/BZD ever**	1.6 (0.9–2.7)	0.12
LTOT***	0.9 (0.5–1.6)	0.69
Long Term NIV****	0.7 (0.2–2.4)	0.56
Male gender	1.8 (1.0–3.2)	0.03
Associations between exposure variables and treatment failure*
Hyperoxemic ever	1.0 (0.5–1.9)	0.9
Hypoxemic ever	1.8 (0.9–3.6)	0.09
Opioids/BZD ever**	1.6 (0.9–2.7)	0.09
LTOT***	1.0 (0.6–1.8)	0.9
Long Term NIV****	0.5 (0.2–1.9)	0.37
Male gender	1.8 (1.1–3.1)	0.03
Associations between exposure variables and late hypercapnic respiratory failure*****
Hyperoxemic ever	0.9 (0.3–2.6)	0.8
Hypoxemic ever	1.0 (0.3–3.3)	1.0
Opioids/BZD ever	1.9 (0.8–4.7)	0.2
LTOT	0.6 (0.2–1.7)	0.3
Long Term NIV	-	-
Male gender	1.2 (0.5–2.9)	0.7
Associations between exposure variables and less than 10 Days Alive and Out of Hospital within 30 days from admission (DAOH-30 < 10)
Hyperoxemic ever	1.0 (0.3–4.2)	0.97
Hypoxemic ever	2.6 (1.0–7.1)	0.05
Opioids/BZD ever	2.3(1.1–4.7)	0.02
LTOT	0.7 (0.3–1.5)	0.35
Long Term NIV	0.2(0.0–2.0)	0.19
Male gender	3.1 (1.5–6.3)	0.002

*OR: Odds ratio. Treatment failure defined as; NIV-treatment initiated after first 24 hours of admission, ICU and or respirator treatment initiated after first

24 hours of admission, hospital admission length >10 days or death” within 30 days after admission.

**Opioids and/or benzodiazepines

***LTOT defined as; Long Term Oxygen Therapy administrated in the home of the patients

****Long Term NIV defined as; Long Term Non Invasive Ventilation administrated in the home of the patients

*****Late hypercapnic respiratory failure defined as; NIV-treatment initiated after first 24 hours of admission, ICU and or respirator treatment initiated after first 24 hours of admission.