Preoperative packed cell volume (PCV) and category of surgery as predictors of intra-operative blood transfusion

SY Yakubu; S Awwalu; LG Dogara; AD Waziri; AI Mamman

doi:10.4103/ais.ais_10_18

ORIGINAL ARTICLE

Year : 2017 | Volume : 7 | Issue : 3 | Page : 95-98

Preoperative packed cell volume (PCV) and category of surgery as predictors of intra-operative blood transfusion

SY Yakubu¹, S Awwalu², LG Dogara³, AD Waziri², AI Mamman²
¹ Department of Anaesthesia, Ahmadu Bello University, Zaria, Nigeria
² Department of Haematology and Blood Transfusion, Ahmadu Bello University, Zaria, Nigeria
³ Department of Haematology, Kaduna State University, Kaduna, Nigeria

Date of Web Publication

29-Oct-2018

Correspondence Address:
Dr. S Y Yakubu
Department of Anaesthesia, Ahmadu Bello University Teaching Hospital, Zaria
Nigeria

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/ais.ais_10_18

Abstract

Background: Preoperative anemia in surgical patients scheduled for major procedures results in poor outcomes, hence the need for full optimization of packed cell volume (PCV) before surgery. This study aims to assess preoperative PCV and category of surgery as predictors of intraoperative blood transfusion in a tertiary healthcare facility in Zaria, Nigeria.
Patients and Methods: This was a retrospective study where hospital records of patient's ≥13 years undergoing elective surgeries at a tertiary hospital in Zaria over a period of 6 months were reviewed. Patients' ages, gender, preoperative PCV, category of surgery, American Society of Anesthesiologists (ASA) scores, and number of units of blood transfused intraoperatively were analyzed using SPSS 20.0.
Results: There were 164 surgeries conducted during the study period. Females constituted 96 (58.5%) of the patients. The mean age and preoperative PCV were 38.9 ± 14.9 years and 36.6 ± 4.9%, respectively. The median (interquartile range) units transfused intraoperatively and ASA scores were 0 (0) and 2 (0), respectively. Spearman's correlation to compare the number of units transfused as a reference point was significant for preoperative PCV (ρ = −0.222, P = 0.004). Regression analyses using category of surgery, ASA scores, age, and preoperative PCV predicted intraoperative transfusion; F(2, 161) = 5.120, P = 0.007, adjusted R² = 0.048 with preoperative PCV and category of surgery predicting the number of units transfused (β =-0.176, P = 0.023) and (β = −0.158, P = 0.041), respectively.
Conclusion: Preoperative PCV and category of surgery although important have a low ability to predict the number of blood units transfused intraoperatively.

Keywords: Category of surgery, intraoperative blood transfusion, packed cell volume, preoperative

How to cite this article:
Yakubu S Y, Awwalu S, Dogara L G, Waziri A D, Mamman A I. Preoperative packed cell volume (PCV) and category of surgery as predictors of intra-operative blood transfusion. Arch Int Surg 2017;7:95-8

How to cite this URL:
Yakubu S Y, Awwalu S, Dogara L G, Waziri A D, Mamman A I. Preoperative packed cell volume (PCV) and category of surgery as predictors of intra-operative blood transfusion. Arch Int Surg [serial online] 2017 [cited 2023 Sep 28];7:95-8. Available from: https://www.archintsurg.org/text.asp?2017/7/3/95/244401

Introduction

The World Health Organization cutoff for anemia for men and women is hemoglobin (Hb) concentration of <130 g/L [packed cell volume (PCV) <39%] and <120 g/L (PCV <36%), respectively, at sea level.^[1] Surgery exposes patients to unique stressors both intra- and postoperatively. The function of Hb in oxygenation is important in wound healing. This may be why a target Hb concentration of at least 130 g/L has been suggested for all adult patients undergoing surgical procedures.^[2] Munoz et al. reported significant associations between preoperative anemia and poor patients' outcomes. These outcomes include length of hospital stay, postoperative complications, and death.^[3]

Major elective surgeries may lead to perioperative blood loss which may cause acute severe anemia, especially in patients with low preoperative Hb concentrations.^[4] Thus, preoperative red cell transfusions are usually administered to increase Hb levels in these patients, thus improving oxygenation and tissue perfusion. However, blood transfusion has some risks especially transfusion transmissible infections (TTIs).^[4],[5]

The perennial dearth of adequate and safe blood coupled with the capital intensive nature of blood and blood products demands proactive measures are taken to predict surgical cases that may require blood transfusion intraoperatively. Unfortunately, baseline published data on the relationship between preoperative PCV/Hb, categories of surgeries, and intraoperative blood transfusion are not available. Hence, this study was conducted to assess preoperative PCV and category of surgery as predictors of intraoperative blood transfusion in our center with a view to providing evidence-based means of assessing intraoperative blood transfusion requirements.

Patients and Methods

This was a retrospective study where the case notes of patient's ≥13 years who had undergone elective surgical procedures at Ahmadu Bello University Teaching Hospital (ABUTH), a tertiary healthcare facility in Zaria, North-West, Nigeria, over a 6-month period (1^st November 2016 and 30^th April 2017), were reviewed and analyzed. Patients' ages, gender, preoperative PCV, category of surgery, American Society of Anesthesiologists (ASA) score, and number of units of blood transfused intraoperatively were determined.

Data were analyzed using IBM SPSS version 20.0. Continuous variables were summarized as means ± standard deviations or medians and interquartile ranges (IQRs = 75^th percentile value –25^th percentile value) as dictated by tests of normality. Categorical variables were summarized as percentages. Spearman's correlation analyses were conducted to determine the relationships between the number of units transfused intraoperatively, patients' ages, and preoperative PCV. Multiple regression analyses were performed to predict the number of units transfused intraoperatively from preoperative PCV, category of surgery, ASA score, and gender. A P value of ≤0.05 was considered significant.

Results

A total of 164 surgeries were conducted during the study period with females constituting 96 (58.5%) of the patients. The mean age and preoperative PCV of the patients were 38.9 ± 14.9 years and 36.6 ± 4.9%, respectively. The median units transfused intraoperatively and ASA scores were 0 (IQR = 0, range = 0–2) and 2 (IQR = 0, range = 1–4). Categories of surgeries undertaken are depicted in [Table 1]. Spearman's correlation analyses to compare the number of units transfused as a reference point were conducted for age (ρ = −0.034, P = 0.669), preoperative PCV (ρ = −0.222, P = 0.004), and ASA scores (ρ =0.104, P = 0.183).

Table 1: Category of surgeries

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Backward multiple regression analyses using category of surgery, ASA scores, age, and preoperative PCV revealed that the model produced by category of surgery and preoperative PCV produced the best fit in predicting intraoperative transfusion; F(2, 161) =5.120, P = 0.007, adjusted R² = 0.048. In this model, preoperative PCV and category of surgery significantly predicted the number of blood units transfused intraoperatively (β = −0.176, P = 0.023) and (β = −0.158, P = 0.041), respectively.

Discussion

The finding of a significant correlation between preoperative PCV and intraoperative blood transfusion in this study is consistent with the findings of some previous studies which suggest that preoperative anemia is associated with subsequent transfusions, morbidity, and mortality.^[6],[7],[8] Beattie et al. in their study on risk associated with preoperative anemia in noncardiac surgery reported that anemia is a common condition in surgical patients and is independently associated with increased mortality. They went further to state that although anemia increases mortality independent of transfusion, it is associated with increased requirement for transfusion, which is also associated with increased mortality.^[7] Similarly, Musallam et al. reported that preoperative anemia, even to a mild degree, is independently associated with risk of 30-day morbidity and mortality in patients undergoing major noncardiac surgery.^[8] The proportion of patients transfused after a given operation varies substantially between hospitals.^{[9],[10],[11]} Roubinian et al. in their study of 21 medical facilities in Northern California reported that variation in RBC transfusion incidence across hospitals decreased from 2010 to 2013.^[10] This may be due to differences in institutional practices and surgical protocols even though patient selection criteria for different types of surgeries may be contributory.

This study produced a model indicating that both preoperative PCV and category of surgeries are important predictors of intraoperative blood transfusion. This is an expected finding as earlier studies have demonstrated that suboptimal Hb levels (<130 g/L for both sexes) are independent predictive factors for perioperative red cell transfusion.^[2] An additional finding in this study is that the category of surgery is a stronger predictor of intraoperative blood transfusion than preoperative PCV. This may be because different surgeries have varying complexities with some involving highly vascular tissues or organs.

We found that only a small proportion of intraoperative transfusions could be predicted by both preoperative PCV and category of surgery. This may be attributed to some limitations in this study as certain variables such as intraoperative blood loss and the proficiency and/or techniques of surgeons were not evaluated in this study. In addition, stages and extents of underlying surgical conditions and specific type of surgery were not assessed. The latter is important as major orthopedic surgeries for example require significant number of blood units compared to other surgeries.^[12] Similarly, the presence of comorbidities and nature of underlying pathology necessitating surgery have been described as important factors in determining preoperative anemia.^[13],[14]

Red cell transfusions are often necessary in major surgeries, comorbidities, and because of perioperative blood loss and are more likely to be required if patients are anemic before operation.^{[12],[15],[16]}

This study thus indicates the need for proactive strategies to predict and meet intraoperative blood transfusion demands. This will entail the hospital blood transfusion committee to elucidate maximum blood ordering schedules for each surgical procedure. This will require the determination of indices such as cross-match transfusion ratio, transfusion probability, and transfusion index for each surgical procedure.^[17]

Finally, we recommend the institution of patient blood management modalities which will involve multidisciplinary, multimodal but individualized strategies that identify modifiable risks and optimize patients' preoperative PCV with the ultimate goal of improving surgical operation outcomes.^[18],[19]

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest

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