Correlation and agreement between arterial and venous blood gas analysis in patients with hypotension—an emergency department‐based cross‐sectional study

Correlation and agreement between arterial and venous blood gas analysis in patients with hypotension—an emergency department‐based cross‐sectional study

Blood gas analysis, Emergency, Hypotension, Oxygenation, Shock

Background Blood gas analysis is integral to assessing emergency department (ED) patients with acute respiratory
or metabolic disease. Arterial blood gas (ABG) is the gold standard for oxygenation, ventilation, and acid–base status

but is painful to obtain. Peripheral venous blood gas (VBG) is a valuable alternative as it is less painful and easy to col-
lect. The comparability of ABG and VBG was studied in various conditions. But in hypotension, previous findings were

inconsistent. So, we studied the correlation and agreement between ABG and VBG in hypotensive patients.
Methodology The study was conducted at the emergency department of a tertiary healthcare center in Northern
India. Patients with hypotension above 18 years who satisfied the inclusion criteria were clinically evaluated. Patients
who require ABG as a part of routine care were sampled. ABG was collected from the radial artery. VBG was obtained
from the cubital or dorsal hand veins. Both samples were collected within 10 min and were analyzed. All ABG and VBG
variables were entered in premade proforma. The patient was then treated and disposed of according to institutional
protocol.
Results A total of 250 patients were enrolled. The mean age was 53.25±15.71 years. 56.8% were male. The study
included 45.6% septic, 34.4% hypovolemic, 18% cardiogenic, and 2% obstructive shock patients. The study found a

strong correlation and agreement for ABG and VBG pH, pCO2, HCO3, lactate, sodium, potassium, chloride, ionized cal-
cium, blood urea nitrogen, base excess, and arterial/alveolar oxygen ratio. Hence, regression equations were made for

the aforementioned. There was no correlation observed between ABG and VBG pO2 and SpO2. Our study concluded
that VBG could be a reasonable alternative for ABG in hypotensive patients. We can also mathematically predict values
of ABG from VBG using regression equations derived.
Conclusions ABG sampling causes most unpleasant experiences to patients and is associated with complications
like arterial injury, thrombosis, air or clotted-blood embolism, arterial occlusion, hematoma, aneurysm formation, and

reflex sympathetic dystrophy. The study has shown strong correlations and agreements for most ABG and VBG param-
eters and can predict ABG mathematically using regression formulas formulated from VBG. This will decrease needle

stick injury, consume less time, and make blood gas evaluation easy in hypotensive settings.

Hari Prasad1

, Nagasubramanyam Vempalli1*, Naman Agrawal2

, U. N. Ajun3

, Ajmal Salam4
,

Soumya Subhra Datta1

, Ashutosh Singhal1

, Nishant Ranjan5

, P. P. Shabeeba Sherin6 and G. Sundareshan7

https://doi.org/10.1186/s12245-023-00486-0

2023

Peri Irawan

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