Abstract
Background
Endoscopic resection of sinonasal Inverted Papilloma (SNIP) tumors has been shown to reduce intra-operative blood loss and recovery time compared to open approaches. The purpose of this study is to investigate the incidence and requirements of blood transfusion for endoscopic SNIP surgeries.
Methods
An individual retrospective cohort study of endoscopic SNIP surgeries over a 10-year period was performed. Age, sex, pre-existing co-morbidity, use of anti-coagulants, tumor type and stage, time of surgery, estimated blood loss and the requirement for blood transfusion were recorded.
Results
82 patients were included (57 males, 25 females). 4 (5%) Stage 1, 7 (8.5%) Stage 2, 62 (75.5%) Stage 3 and 9 (11%) Stage 4 SNIP tumors were identified according to the Krouse staging system. 3 (4%) patients required blood transfusion. 3 of the 9 (33%) Stage 4 tumors required blood transfusion. Stage 4 tumors were significantly associated with blood transfusion (p < 0.05). Higher staged tumors were associated with greater blood loss (p < 0.05) than lower staged cases. No other tumor stage required blood transfusion and no other pre-operative variable was associated with requirement for blood transfusion.
Conclusion
Endoscopic SNIP resections rarely require blood transfusions. No pre-operative factor other than tumor stage is associated with the requirement for blood transfusion. We would therefore suggest that only Stage 4 SNIP tumors require pre-operative type and screen.
Introduction
Sinonasal Inverted Papilloma (SNIP) is a benign epithelial growth occurring in the nose and paranasal sinuses [1]. These tumors commonly originate in the lateral nasal wall and/or middle meatus and can later extend to the surrounding paranasal sinuses [1]. Complete excision is the treatment of choice for these locally aggressive tumors with malignant potential [1–4]. Advances in endoscopic technology and instrumentation have improved visualization and surgical outcomes [1]. The evidence now suggests that endoscopic SNIP resection gives as good, if not better results than open approaches [5–8]. Endoscopic tumor resections are less invasive and associated with reduced surgical time, anaesthesia risk, shorter hospital stay, fewer intra-operative complications and lower recurrence rates when compared to the previous open craniofacial approach [3, 4]. Nevertheless, excision of these tumors may cause significant bleeding and may occasionally require blood transfusion [4, 9].
Blood transfusions restore and maintain circulating blood volume, correct anaemia and coagulation disorders [10]. However, allogeneic blood transfusions may pose a risk for transmissible diseases and adverse reactions [11]. In order to ensure accurate and compatible use of donor units, blood ordering practices such as type and screen testing and crossmatching have been utilized by transfusion laboratories [12]. The recipient's blood is type and screened to determine ABO and Rh group and presence of RBC alloantibodies [12, 13]. Crossmatching is utilized to determine patient and donor RBC, plasma and antibody compatibility [13]. This can be done electronically in some hospitals to save time and resources, as opposed to serological testing [14]. Although blood-ordering protocols for elective surgery are present to increase patient safety, practices of over-ordering units can develop [11, 12]. This may occur due to habit, inexperienced staff or inadequate transfusion prediction models [11, 12, 15]. To assess the efficiency of routine blood ordering practices in elective surgery, several studies have observed the ratio of crossmatched to transfused patients, average number of units transfused for particular procedures and the transfusion probability coefficient (number of transfused patients/number of procedures) [9, 12, 15, 16]. These studies have found that a tendency towards over-ordering of blood can consume blood bank resources and increase blood outdating [9, 14–17].
It is unclear whether routine requisitions of blood are necessary for patients who undergo endoscopic SNIP surgery. To investigate the incidence and requirements for blood transfusion, we have conducted a retrospective chart review of endoscopic SNIP resections at our institution.
Methods
A retrospective chart review of endoscopic SNIP resections performed at the St. Paul's Sinus Centre (SPSC) between April 2000 to August 2010. This is a tertiary level sinus centre located at the University of British Columbia in Vancouver, Canada. The charts of those patients who had undergone computer assisted endoscopic resections were examined for patient demographic data, intra-operative details, type and screen ± crossmatch requisitions and the requirement for blood transfusion. Histopathological examination by the St. Paul's Hospital Laboratory was used to determine tumor type from intra-operative specimens.
Krouse staging system for inverted papilloma
The incidence of type and screen testing ± crossmatching was determined from the St Paul's Transfusion Laboratory, through electronic and printed records. Patients who had undergone type and screen testing had their blood group identified and screened for the presence of Rh antibodies. The decision whether to type and screen a patient was made by the senior author along with the pre-assessment staff and anesthesiologist. If the surgical procedure had the potential to require blood transfusion, as judged by the senior author, crossmatching was completed with the required units reserved. All blood crossmatching was electronically completed through the Transfusion Laboratory. Similarly, blood transfusions were evaluated through Laboratory records and included total administered units. The amount of blood transfused was determined by evaluating the total amount of blood lost, the rate of blood loss, anesthesiology concern and the patient's overall health.
The study outcomes were occurrence of “type & screen”, “cross-match” and “blood transfusion”. They were defined as binary variables in the analysis. For each outcome both univariate and multivariate logistic regression models were fitted to patient demographics and intra-operative variables with the occurrence of the outcome of interest as the dependent variable. A two-sided P value of less than 0.05 was considered to indicate statistical significance. Statistical analysis was conducted using Prism GraphPad Version 5.0.
Results
Total population
Demographic and pre-operative details of total study population
Transfusion
3 (4%) patients required blood transfusion, all of whom had Krouse Stage 4 tumors. 3 of 9 (33%) Stage 4 tumors therefore required blood transfusion. Mean total blood loss for Stage 4 tumors (911 ml) was greater than Stage 3 (461 ml), Stage 2 (636 ml) and Stage 1 tumors (71 ml) (Figure 1). The three transfusion cases received one, two or four units of blood respectively. Higher staged tumors were associated with greater total blood loss than lower staged cases (p < 0.05). Stage 4 tumors were significantly associated with blood transfusion (p < 0.05). No significant association was found between tumor stage and time of surgery (p > 0.05). Overall, 1 in 27 SNIP cases were found to require blood transfusion. Higher staged tumors (Stage 3 and 4) that were found to have significant bleeding during surgery, the transfusion ratio increased to 1 in 24. For Krouse Stage 4, the transfusion ratio was 1 in 3.
Mean total blood loss (ml) versus Krouse Staging for Inverted Papilloma.
Type and screen testing
Krouse staging for cases type and screen tested and type and screen to transfusion ratio
Crossmatching
Krouse staging for crossmatched cases and crossmatch to transfusion ratio
Expenditure
The estimated fees for each procedure were obtained from the Transfusion Laboratory and the Department of Finance to assess the cost of our current blood ordering protocol. The direct cost of type and screen testing was estimated to be ․67.49. This included identification of patient blood type (ABO), presence of Rh groups and screening of circulating antibodies. Therefore, the total expenditure for all patients’ type and screen tested (n = 21) was approximately ․1417.29. Similarly, the direct cost for electronic crossmatch testing was estimated to be ․8.18. Patients’ blood was digitally matched to the donor blood bank to determine compatibility. Therefore, the total expenditure for all patients crossmatch tested (n = 5) was approximately ․40.90. The combined cost of blood ordering procedures was ․1458.19. All prices have been provided in Canadian dollars.
Discussion
In this study we have observed that SNIP stage, operating time and total blood loss are the only measures that are associated with blood transfusion. It therefore appears that the only pre-operative variable identified in this study that can be used to predict who may require blood transfusion is tumor stage. This highlights the importance of a detailed pre-operative patient assessment to accurately stage the tumor. Advances in CT imaging and endoscopic visualization have allowed for better determination of the extent of SNIP tumors, allowing for improved assessment and surgical removal [19]. The amount of blood a patient would receive if transfused could not be predicted before surgery. Vascularity of the tumor or tumor bed, site of origin of the tumor and extent of resection during tumor removal were factors encountered intra-operatively that could not be accurately predicted pre-operatively. The study was performed in a tertiary referral sinus centre where the SNIP cases seen tend to be advanced, with 86% being Krouse Stage 3 or above. The incidence of blood transfusion may be even lower in non-tertiary centres where the cases are more likely to be of a lower Krouse stage.
Information gained from conducting an internal audit of surgical blood orders made at the St. Paul's Sinus Centre can be used to establish precise guidelines for the allocation of blood resources. As described by Lin et al. (2006), for elective procedures where transfusion probability is less than five percent, pre-operative blood ordering can be disregarded [12]. We have found that the incidence of blood transfusion using the endoscopic approach for all sinonasal tumor resections is 4%. Approximately one out of seven patients type and screen tested was subsequently transfused (Figure 1). Those patients that were type and screened but not transfused had lower SNIP staging than those who required transfusion.
Our study suggests high SNIP tumor stage is an important factor that needs to be considered when deciding which patients require type and screen preoperatively. By determining SNIP stage from pre-operative CT imaging and endoscopic assessment, an efficient allocation of blood resources and surgical strategies can be made. Type and screen testing was approximately eight times more costly than electronic crossmatching, and therefore if unnecessary testing can be reduced a significant saving can be made. The overall incidence of blood transfusion was less than 5%. We therefore propose that routine type and screen is not required for all endoscopic resections of SNIP. However, blood transfusion was required in 33% of Stage 4 tumors, well above the 5% cut off suggested. We therefore recommend that type and screen testing should only be requested for Stage 4 SNIPs. If this protocol was followed in our series then all 9 Stage 4 SNIPs would have required type and screen testing at a cost of C․607.41, an overall saving of C․809.88. Introducing blood-ordering guidelines for surgical procedures can result in reduced costs, a lowering of the consumption of valuable blood bank resources as well as a decrease in blood outdating.
Conclusion
Endoscopic SNIP resections rarely require blood transfusions. No pre-operative factor other than tumor stage was associated with the requirement for blood transfusion. We therefore recommend that only those patients with Stage 4 SNIP tumors require pre-operative type and screen.
Footnotes
Acknowledgments
We would like to thank our colleagues within the Department of Statistics at the University of British Columbia, St. Paul's Hospital. We are especially grateful to Hong Qian for statistical analysis and insight throughout data collection. We also would like to acknowledge Rachelle Dar Santos for her assistance and support in the successful completion of this project.
There are no financial disclosures or conflicts of interest to be reported.