Impact of Blood Sampling in Critical Care Settings in South India: Prospective Observational Study

Background: Frequent and unnecessary sampling could lead to blood loss, which is a major factor causing iatrogenic anaemia. Optimising blood sampling practices could help prevent the need for blood transfusions. Our study aims to assess the blood loss, haemoglobin drop, and blood transfusion requirement due to blood sampling in critical care units. Methods: A prospective observational study was carried out in the adult critical care units of a tertiary care hospital over three months in Coimbatore, South India. A total of 193 consecutive patients were included by convenience sampling. Blood loss incurred other than blood sampling was observed to negate the bias. Results: Thirty-one (15.8%) patients experienced a significant drop in haemoglobin, and the average blood volume drawn was 87 ml per patient during ICU admission. Patients with invasive catheters incurred higher blood loss and received more blood transfusions (63 units) compared to those with non-invasive catheters (4 units). Unplanned blood samples (stat) were 1186 (9.96 per patient) with invasive catheters. The calculated p-value for blood wastage and transfusion is highly significant (p=0.013). The highly substantial p-values were seen for blood withdrawn between invasive sampling and peripheral sampling per patient and per day (p=0.000 & p=0.00). Conclusion: Our study suggests that reducing the incidence of iatrogenic anaemia and blood transfusion requirements is possible using a closed blood sampling system, especially for sicker patients and those expected to stay for more than 5 days, avoiding unplanned and frequent investigations, using small-volume blood collection tubes, and planned blood sampling timings 12 hours apart as an ICU protocol.