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Age and Ageing2008; 37: 173178 The Author 2008. Published by Oxford University Press on behalf of the British Geriatrics Society.doi:10.1093/ageing/afm161 All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org

Anaemia impedes functional mobility after hip

fracture surgery

NICOLAI B. FOSS1,2, MORTEN TANGE KRISTENSEN3, HENRIK KEHLET4

1Department of Anaesthesia, Hvidovre University Hospital, Hvidovre, Denmark2Department of Orthopaedic Surgery, Hvidovre University Hospital, Hvidovre, Denmark3Department of Physiotherapy, Hvidovre University Hospital, Hvidovre, Denmark4Department of Surgical Pathophysiology, Rigshospitalet, Copenhagen, Denmark

Address correspondence to: Nicolai B. Foss. Email: nbf@comxnet.dk

Abstract

Background: the impact of anaemia on the outcome after a hip fracture surgery is controversial, but anaemia can potentiallydecrease the physical performance and thereby impede post-operative rehabilitation. We therefore conducted a prospectivestudy to establish whether anaemia affected functional mobility in the early post-operative phase after a hip fracture surgery.Patients and Methods: four hundred and eighty seven consecutive hip fracture patients, treated according to a well-definedmultimodal rehabilitation programme with a uniform, liberal transfusion threshold, were studied. Hb was measured on eachof the first three post-operative days, and anaemia defined as Hb

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orthopaedics at Hvidovre University Hospital were studiedprospectively. The inclusion criteria wereprimary hip fractureoccurring in the community in patients with a prefracturewalking function independent of human assistance regardlessof walking aids used, no pathological fracture or surgeryresulting in a Girdlestone status. Patients were excludedfrom the analysis if they were not able to participate in thephysical therapy programme due to mobilisation restrictionon the advise of the operating surgeon or transfer to anotherward for medical complications.

This study is part of Hvidovre University Hospitals HipFracture Project, which was evaluated by the local ethicalcommittee, who had no objections to the project andconcluded that no written patient consent was necessary.The study was approved by the Danish data protectionagency.

Perioperative procedures

All patients admitted to the unit received surgical interventionfor their fracture. Patients were treated perioperatively in aspecial hip fracture unit with a multimodal rehabilitationprogram. The rehabilitation program included surgerywithin 24 h, epidural anaesthesia and epidural analgesiainitiated immediately after admittance and continued for96 h post-operatively [14]. From admission until the fourthpost-operative day patients received supplemental oxygentherapy 2 l min1 whenever supine. All patients receivedantibiotics with cefuroxim 1.5 g immediately preoperativelyand antithrombotic prophylaxis with low-molecular weightheparin (enoxaparin40 mg1 SConcedaily) fromthe timeofadmission. Patients were on a regular diet supplemented bythree daily protein drinks in the entire perioperative periodexcluding 6 h of preoperative fasting.

Preoperative fluid therapy consisted of rehydrationfluid (Na 40 mmol/l, K 20 mmol/l, glucose 250 mmol/l)20 ml/kg immediately upon admission; intraoperatively,an infusion of isotonic saline 5 ml/kg/h was provided,supplemented by 6% hydroxyethyl starch 130/0.4 on signsof hypovolaemia. Intraoperative blood loss was replacedby 6% hydroxyethyl starch 130/0.4, at a rate of 1:1 untilHb fell below 100 g/l, at which point transfusion of redblood cells (RBC) was initiated. In the post-anaesthesiacare unit (PACU) all patients received 500 ml IV glucose(278 mmol/l). Post-operative fluid therapy was standardisedand intravenous fluids were only administered if daily oralintake was

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of intensive rehabilitation, were only then transferred to asecondary rehabilitation facility.

Data collection

Data were gathered prospectively. Medical conditions,American Society of Anaesthesiologists (ASA) classification,type of surgery, as well as complications, length of stay and30-day mortality were all registered, the latter establishedvia the Danish civil register. A complication was defined asbeing present in any patient that post-operatively developedany of the following: cerebrovascular accident, delirium,acute myocardial infarction or unstable angina, acutecongestive heart failure, new onset arrhythmia, pneumonia,respiratory insufficiency, gastric or duodenal ulceration,renaldysfunction, septicaemia, pulmonary embolism, deepvenousthrombosis or woundinfection.For theanalysisof theimpactof complications on early post-operative functional mobility,only those complications occurring before the fourth post-

operative day were included.

Statistical analysis

Possible correlations were tested for with the Spearmansrho. Tests for significant differences between categoricaldata in the univariate analyses was performed with the chi-square test, and adjusted for linear to linear associationwhere appropriate, for ordinal and continuous data theMann Whitney testwas used.Multivariatelogistic regressionanalysis was done to identify independent factors associatedwith independent walking on the third post-operative day.The type of surgical procedure was entered in the analysiscoded as dummy variables with two parallel screws chosenas control. The level of significance was set at P

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measured Hb value below 100 g/l is shown. About 13 ,24 and 36% of the patients were able to walk independentlywithout human assistance on the first, second and third

day, respectively. A significant linear association between theability to walk independently, requiring human assistance ornot being able to walk at all and an Hb < 100 g/l was presenton each of the 3 days independently. Patients with Hb 75 years ofage, dementia, poor prefracture functional mobility (NMS0 5) and post-operative medical complications were themost prominent risk factors followed by a haemoglobin

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Table 3. Multivariate analysis of factors impeding functional mobility and the ability to walkindependently or with human assistance on the third post-operative day (n= 430)

Ability to walk on the third post-operative day

Univariate analysis Multivariate analysis

Odds ratio Odds ratio

(95% CI) P (95% CI) P. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

>75 years 0.16 (0.070.35)

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Acknowledgements

This work received financial support from IMK-almene fond(Copenhagen, Denmark).

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Received 3 June 2007; accepted in revised form 31 August 2007

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