Perioperative blood loss and transfusion requirements in patients with fractured neck of femur

EDITOR: Repair of femoral neck fractures constitutes a significant workload within most orthopaedic departments. These injuries occur mainly in an elderly population in the presence of underlying co-morbidity and, as a consequence, are associated with significant postoperative morbidity and mortality [1,2]. The care of these patients requires efficient, multidisciplinary management - avoiding the delays in ward transfer, surgery and postoperative rehabilitation that have been identified as contributing to a poor outcome [2]. Within our institution it had been observed that for certain individuals a delay in measuring the postoperative haemoglobin concentration and appropriate prescribing of blood transfusion might have contributed to the failure of early postoperative mobilization, thereby risking well-recognized complications. Therefore, we audited two series of patients undergoing repair of fractured neck of femur to assess current practice, perioperative haemoglobin decrease and subsequent blood transfusions. The patient records of two series of 50 consecutive patients, undergoing either dynamic hip screw or hemiarthroplasty for repair of fractured neck of femur, were reviewed retrospectively at Lincoln County Hospital (a 500 bed district general hospital) and at the Queen's Medical Centre, Nottingham (a tertiary referral, university hospital) in the UK. Factors recorded included age, ASA status, type of anaesthetic, pre- and postoperative haemoglobin concentrations and estimated blood loss (if documented). Also recorded were blood transfusions prescribed during the 5 days following surgery and whether, during the intra- or postoperative period, the anaesthetist or the responsible surgical team initiated the transfusion. If a patient received a blood transfusion preoperatively, the post-transfusion haemoglobin value was recorded. Decisions on the transfusion management of patients at both hospitals were at the discretion of the attending clinicians, in the absence of hospital policies. Data are presented as the mean ± standard deviation and as the median (interquartile range). Statistical analyses were performed using unpaired, t-tests and α was set at 5%. The results for the first series of 50 patients (at the Lincoln County Hospital) were as follows. Twenty-five patients undergoing dynamic hip screw fixation and 25 undergoing hemiarthroplasty were studied. Both groups were similar with respect to age, ASA status, and preoperative haemoglobin for the dynamic hip screw and hemiarthroplasty groups respectively (12.6 ± 1.5 g dL−1 vs. 12.6 ± 1.5 g dL−1). The reduction in haemoglobin concentration after operation differed significantly between the dynamic hip screw group (3.0 ± 1.5 g dL−1) and hemiarthroplasty group (2.3 ± 1.2 g dL−1; P = 0.03). Falls in haemoglobin concentration of >4 g dL−1 were twice as frequent in the dynamic hip screw group, occurring in six of 25 (24%) patients. Blood transfusions were more frequent and larger in the dynamic hip screw group with 14 of 25 (56%) patients receiving a transfusion (2.5 (2-3) units). In the hemiarthroplasty group eight of 25 (32%) patients received a transfusion (2 (1.25-2) units). The transfusion trigger was consistently haemoglobin <9.0 g dL−1. The haemoglobin concentration was measured on the first postoperative occasion up to 3 days after surgery, with three patients having values <7.0 g dL−1 in the dynamic hip screw group and none in the hemiarthroplasty group. Blood loss was inconsistently recorded in patients' notes. It was documented in 19 of 50 cases (six dynamic hip screw and 13 hemiarthroplasty patients). Estimates of blood volume loss were up to 600 mL in both groups; however, the small number in which this was documented precluded any statistical comparison. Three transfusions were initiated in the dynamic hip screw group, and two in the hemiarthroplasty group, by the anaesthetist. None of these patients required a further transfusion. The results for the second series of 50 patients (at the Queen's Medical Centre) were as follows. Twenty-five patients undergoing dynamic hip screw fixation and 25 undergoing hemiarthroplasty were studied. The two populations were similar with respect to age, ASA grade and preoperative haemoglobin concentration (12.5 ± 1.3 g dL−1 vs. 12.9 ± 1.9 g dL−1) for the dynamic hip screw and hemiarthroplasty groups, respectively. The reduction of perioperative haemoglobin concentration was again greater in the dynamic hip screw group (2.8 ± 1.3 g dL−1) than the hemiarthroplasty group (2.2 ± 1.3 g dL−1), which approached, but did not attain, statistical significance (P = 0.06). Overall, the reductions were similar to those recorded in the previous audit. However, blood transfusions were less frequent, occurring in eight patients (32%) with dynamic hip screw fixation and four (16%) with hemiarthroplasty repair. All of these patients received a 2 unit transfusion. Again, the transfusion trigger was consistently haemoglobin <9 g dL−1. Three transfusions were initiated, two in the dynamic hip screw group and one in the hemiarthroplasty group, by the anaesthetist. The haemoglobin concentration in one patient receiving a dynamic hip screw was <7.0 g dL−1 postoperatively. Across both series, factors that have been shown to influence blood loss (i.e. age, ASA status and type of anaesthetic [3]) had an inconclusive effect in this study. Also of note is that >80% of patients with a preoperative haemoglobin <11 g dL−1 received a transfusion within 5 days of surgery. Unrecognized blood loss in patients undergoing repair of fractured neck of femur may delay postoperative mobilization and influence morbidity and mortality. This audit revealed a high postoperative transfusion rate in this population, the majority initiated by ward clinicians. Several very low postoperative haemoglobin values were recorded, particularly in the dynamic hip screw groups. These observations suggest a frequent underestimate of blood losses sustained perioperatively, especially in those undergoing dynamic hip screw repair. Often haemoglobin values taken on admission are recorded as the preoperative value, and together with intraoperative blood loss, are the basis upon which blood transfusion is prescribed. However, this preoperative value is unlikely to be accurate because these patients are often hypovolaemic when first assessed. This will often be due to a poor fluid intake prior to admission but also continuing haematoma formation around the fracture site that may contribute to a significant volume loss. This will be particularly apparent in the dynamic hip screw group that will predominantly have sustained an extracapsular fracture, resulting in a larger fracture site, no anatomical boundary to the haematoma and subsequently greater haemoglobin reduction. Other contributing factors to this underestimate may be the poor routine recording of intraoperative blood loss, the infrequency of intraoperative transfusions observed, and inadequate postoperative follow-up. Similar findings demonstrating blood transfusion requirements in this population have been previously published; however, it is apparent that this issue is still not commonly appreciated [4,5]. In addition, delays in measuring and recording haemoglobin values after operation, which ideally should take place on the first postoperative day, will inevitably affect any appropriate blood transfusion and possibly early patient rehabilitation. There is an apparent lack of evidence on which to base our transfusion trigger of haemoglobin 9.0 g dL−1 in this population. The UK Association of Anaesthetists has published evidence-based guidelines on appropriate transfusion triggers and optimum haemoglobin values for various patient populations. Here it is suggested that levels down to 8.0 g dL−1 are well tolerated in most patients [6]. However, in the elderly and those with significant cardiovascular disease, higher values may be more appropriate. One large study in a similar population showed no additional mortality at 30 and 90 days in patients whose haemoglobin concentration fell to 8.0 g dL−1[7]. However, it was not established whether morbidity was higher or if hospital stay was prolonged, which is particularly relevant in this elderly population. It is likely that future studies may indicate a lower transfusion trigger to be optimal; however, until such evidence is available it is appropriate to follow the guidance issued by the Association of Anaesthetists. We acknowledge that because this survey is a retrospective review of patient records, we have failed to control several confounding factors (i.e. surgical experience, specific fracture type, hydration status of patients and perioperative fluid management). However, a wider appreciation of the potential for large perioperative blood losses in patients undergoing repair of fractured neck of femur is required. It is apparent that blood transfusions are frequently required after operation and anaesthetists have an important role in ensuring that haemoglobin concentrations do not fall excessively in the postoperative period. This may require the measurement of haemoglobin concentration in the recovery unit, either as a bedside test or formal laboratory sample, and the prescription of an appropriate blood transfusion to optimize the chances of a successful outcome. P. D. Marval J. G.