The Influence of Arterial Tourniquet Applied During Limb Surgery on Postoperative Hemoglobin Level- a Single Centre Prospective Observational Study

Abstract

Background: Limb surgeries are a major contributor of surgical burden, especially in low and middle-income countries. These surgeries are associated with considerable blood loss. Therefore anaesthetists and surgeons are encouraged to adopt mechanisms aimed at minimizing blood loss. The use of a tourniquet remains a popular method of reducing blood loss during limb surgery. Main objective: To determine the influence of arterial tourniquet applied during limb surgery on postoperative hemoglobin level at Kenyatta National Hospital. Methodology: This was a prospective observational study carried out over 10 weeks (November 2020 to January 2021) at KNH. Participants were recruited in the operating theatre waiting area after meeting the inclusion criteria and using systematic sampling, a total of 81 participants were recruited into the study. They were followed up throughout the surgery and up-to day two post-surgery. Data were collected and uploaded into Research Electronic Data Capture (REDCap). These data were exported to SPSS Version 21 for cleaning and analysis. Results: The mean age of the participants was 34.6 (SD 14.4), range of 8.0 years to 70.0 years. There were 65 (80.2%) male and 16 (19.8%) female participants. A majority (85.2%) of the patients had orthopedic conditions while 14.8% had other non-orthopedic conditions. The mean preoperative hemoglobin level was 12.5 (SD 1.5) g/dl in male participants and 12.6 (SD 1.7) g/dl in female participants, with a mean difference of 0.1 g/dl. This was not statistically significant (p = 0.679). The mean tourniquet cuff inflation pressures for the upper limb was 240.7 (SD 25.2) mmHg while for the lower limb it was 322.4 (SD 38.1) mmHg. The mean inflation time for the upper limb was 76.6 (SD 37.0) minutes while for the lower limb it was 89.2 (SD 32.3) minutes. The mean postoperative hemoglobin level was 10.5 (SD 1.7) g/dl. A paired-sample t-test of the differences in the mean Hb levels preoperatively and postoperatively revealed a mean difference of 2.0 (95% CI, 1.6 to 2.2). This was statistically significant (p <0.001). Conclusion: The majority of participants had a pre-op Hb level of more than 10g/dl (96.3%), while postop a significant number (37%) had a Hb level of less than 10g/dl hence the need to do a Hb level post-op. Tourniquet cuff inflation pressures used were high compared to recommended values. Postoperatively there was a reduction in Hb level compared to preoperative levels with a mean difference of 2.0 g/dl which was statistically significant (p<0.001).