Andy J. Scally

Effect of a patient blood management programme on preoperative anaemia, transfusion rate, and outcome after primary hip or knee arthroplasty: a quality improvement cycle

BACKGROUND There are few data on the associations between anaemia, allogeneic blood transfusion (ABT), patient blood management, and outcome after arthroplasty in the UK. National agencies nevertheless instruct NHS Trusts to implement blood conservation measures including preoperative anaemia management. Internationally, blood management programmes show encouraging results. METHODS We retrospectively audited 717 primary hip or knee arthroplasties in a UK general hospital and conducted regression analyses to identify outcome predictors. We used these data to modify previously published algorithms for UK practice and audited its introduction prospectively. The retrospective audit group served as a control. RESULTS Preoperative haemoglobin (Hb) concentration predicted ABT (odds ratio 0.25 per 1 g dl(-1), P<0.001). It also predicted the length of stay (LOS, effect size -0.7 days per 1 g dl(-1), P=0.004) independently of ABT, including in non-anaemic patients. Patient blood management implementation was associated with lower ABT rates for hip (23-7%, P<0.001) and knee (7-0%, P=0.001) arthroplasty. LOS for total hip replacement and total knee replacement decreased from 6 (5-8) days to 5 (3-7) and 4 (3-6) days, respectively, after algorithm implementation (P<0.001). The all-cause re-admission rate within 90 days decreased from 13.5% (97/717) before to 8.2% (23/281) after algorithm implementation (P=0.02). CONCLUSIONS We conclude that preoperative Hb predicts markers of arthroplasty outcome in UK practice. A systematic approach to optimize Hb mass before arthroplasty and limit Hb loss perioperatively was associated with improved outcome up to 90 days after discharge.

Efficacy and safety of different techniques of paravertebral block for analgesia after thoracotomy: a systematic review and metaregression

Various techniques and drug regimes for thoracic paravertebral block (PVB) have been evaluated for post-thoracotomy analgesia, but there is no consensus on which technique or drug regime is best. We have systematically reviewed the efficacy and safety of different techniques for PVB. Our primary aim was to determine whether local anaesthetic (LA) dose influences the quality of analgesia from PVB. Secondary aims were to determine whether choice of LA agent, continuous infusion, adjuvants, pre-emptive PVB, or addition of patient-controlled opioids improve analgesia. Indirect comparisons between treatment arms of different trials were made using metaregression. Twenty-five trials suitable for metaregression were identified, with a total of 763 patients. The use of higher doses of bupivacaine (890-990 mg per 24 h compared with 325-472.5 mg per 24 h) was found to predict lower pain scores at all time points up to 48 h after operation (P=0.006 at 8 h, P=0.001 at 24 h, and P<0.001 at 48 h). The effect-size estimates amount to around a 50% decrease in postoperative pain scores. Higher dose bupivacaine PVB was also predictive of faster recovery of pulmonary function by 72 h (effect-size estimate 20.1% more improvement in FEV1, 95% CI 2.08%-38.07%, P=0.029). Continuous infusions of LA predicted lower pain scores compared with intermittent boluses (P=0.04 at 8 h, P=0.003 at 24 h, and P<0.001 at 48 h). The use of adjuvant clonidine or fentanyl, pre-emptive PVB, and the addition of patient-controlled opioids to PVB did not improve analgesia. Further well-designed trials of different PVB dosage and drug regimes are needed.

The effect of refractive blur on postural stability

The effect of refractive blur upon postural stability was investigated under three conditions: normal standing, standing with input from the somatosensory system disrupted and standing with input from the somatosensory and vestibular systems disrupted. Standing stability was assessed using the centre of pressure (COP) signal from force plate data in four young subjects (mean 23.9 ± 3.1 years) and five repeated sets of measurements were taken. The subjects looked straight ahead at a horizontal and vertical square wave pattern of 2.5 cycles (degree)−1. Under each of the three test conditions, standing stability was measured with the optimal refractive correction and under binocular blur levels of 0, + 1, + 2, + 4, and + 8 D and with eyes closed. In the normal standing condition, dioptric blur had only a mild effect on postural stability. However refractive blur produced large increases in postural instability when input from one or both of the other two sensory systems were disrupted. We hypothesized that dioptric blur would have an even great effect on postural stability if the visual target used was of higher spatial frequency. This was confirmed by repeated measurements on one subject using a target of 8 cycles (degree)−1. The study highlights the possible importance of an optimal correction to postural stability, particular in situations (or people) where input from the somatosensory and/or vestibular systems are disrupted, and where the visual surrounds are of high spatial frequency.

Lipidomic analysis reveals prostanoid profiles in human term pregnant myometrium

Prostanoids modulate the activity of human pregnant myometrium and their functional role can be appreciated through characterisation of prostanoid receptors and tissue concentration of prostanoids. We have applied a lipidomic approach to elucidate the profile of prostanoids in human non-labouring and labouring myometrium. We have identified a total of nineteen prostanoids including prostacyclin, thromboxanes, prostaglandins and dihydro-prostaglandins. Prostacyclin was the predominant prostanoid in both non-labouring and labouring myometria, with PGD(2) and PGF(2alpha) being the second most abundant. Although the total amount of prostanoids was increased in the labouring tissue, PGE(2) and 13,14-dihydro-15-keto-PGE(2) were the only prostanoids to increase significantly at early and late labour (p< or =0.001). Our data suggest that PGF(2alpha) plays an important role in parturition, whilst the increase in PGE(2) could occur to facilitate cervical dilation and relaxation of the lower myometrium during labour. Although the elevation in TXA(2) was less marked than expected, in terms of translation to function even a relatively small increase in the level of this potent spasmogen may have significant effects.

Bilateral Changes in Foveal Structure in Individuals with Amblyopia

PURPOSE To examine foveal structure in amblyopia using spectral-domain optical coherence tomography (SD-OCT). DESIGN Prospective, cross-sectional study. PARTICIPANTS AND CONTROLS Two subject groups were recruited to the study: 85 amblyopes (34 adults, 51 children) and 110 visually normal controls (44 adults, 66 children). METHODS A detailed eye examination, including an SD-OCT scan, was performed in all participants. A total of 390 eyes of 195 subjects were imaged using a 3-dimensional (3D) macula scan covering a nominal 6 × 6-mm area with a resolution of 256 × 256 (65,536 axial scans). Data from the B-scans bisecting the fovea both horizontally and vertically were fitted with a mathematical model of the fovea to determine a range of foveal parameters. MAIN OUTCOME MEASURES Foveal thickness, foveal pit depth, and foveal pit slope. RESULTS Bilateral differences between the eyes of amblyopes compared with visually normal controls were found. The difference between foveal structure in amblyopic participants relative to structure in subjects with normal vision persisted even when variables such as age, ethnicity, axial length, and sex were taken into account. Amblyopes showed increased foveal thickness (+8.31 μm; P = 0.006) and a reduction in pit depth in the horizontal meridian (-10.06 μm; P = 0.005) but not in the vertical meridian (P = 0.082) when compared with subjects with normal vision. Foveal pit slopes were found to be approximately 1 degree flatter in the nasal (P = 0.033) and temporal (P = 0.014) meridians in amblyopes, but differences between amblyopes and controls in the superior (P = 0.061) and inferior (P = 0.087) meridians did not reach statistical significance. No statistically significant interocular differences were found in the foveal structure between amblyopic and fellow eyes. CONCLUSIONS Differences were found in the foveal structure in both eyes of amblyopes compared with subjects with normal vision. These differences consisted of increased foveal thickness, reduced pit depth when measured along the horizontal meridian, and flattening of the nasal and temporal sides of the foveal pit.

Adaptive gait changes in long-term wearers of contact lens monovision correction

Introduction:  The aim of the present study was to determine adaptive gait changes in long‐term wearers of monovision correction contact lenses by comparing gait parameters when wearing monovision correction to those observed when wearing binocular distance correction contact lenses.

The effects of monocular refractive blur on gait parameters when negotiating a raised surface.

Falls in the elderly are a major cause of mortality and morbidity. Elderly people with visual impairment have been found to be at increased risk of falling, with poor visual acuity in one eye causing greater risk than poor binocular visual acuity. The present study investigated whether monocular refractive blur, at a level typically used for monovision correction, would significantly reduce stereoacuity and consequently affect gait parameters when negotiating a raised surface. Fourteen healthy subjects (25.8 ± 5.6 years) walked up to and on to a raised surface, under four visual conditions; binocular, +2DS blur over their non‐dominant eye, +2DS blur over their dominant eye and with their dominant eye occluded. Analysis focussed on foot positioning and toe clearance parameters. Monocular blur had no effect on binocular acuity, but caused a small decline in binocular contrast sensitivity and a large decline in stereoacuity (p < 0.01). Vertical toe clearance increased under monocular blur or occlusion (p < 0.01) with a significantly greater increase under blur of the dominant eye compared with blur of the non‐dominant eye (p < 0.01). Increase in toe clearance was facilitated by increasing maximum toe elevation (p < 0.01). Findings indicate that monocular blur at a level typically used for monovision correction significantly reduced stereoacuity and consequently the ability to accurately perceive the height and position of a raised surface placed within the travel path. These findings may help explain why elderly individuals with poor visual acuity in one eye have been found to have an increased risk of falling.

Adaptive gait changes in older people due to lens magnification

Citation information: Chapman GJ, Scally AJ & Elliott DB. Adaptive gait changes in older people due to lens magnification. Ophthalmic Physiol Opt 2011, 31, 311–317 doi: 10.1111/j.1475‐1313.2010.00807.x

Medicines Reconciliation Using a Shared Electronic Health Care Record

Objective: This study aimed to evaluate the use of a shared electronic primary health care record (EHR) to assist with medicines reconciliation in the hospital from admission to discharge. Methods: This is a prospective cross-sectional, comparison evaluation for 2 phases, in a short-term elderly admissions ward in the United Kingdom. In phase 1, full reconciliation of the medication history was attempted, using conventional methods, before accessing the EHR, and then the EHR was used to verify the reconciliation. In phase 2, the EHR was the initial method of retrieving the medication history-validated by conventional methods. Results: Where reconciliation was led by conventional methods, and before any access to the EHR was attempted, 28 (28%) of hospital prescriptions were found to contain errors. Of 99 prescriptions subsequently checked using the EHR, only 50 (50%) matched the EHR. Of the remainder, 25% of prescriptions contained errors when verified by the EHR. However, 26% of patients had an incorrect list of current medications on the EHR. Using the EHR as the primary method of reconciliation, 33 (32%) of 102 prescriptions matched the EHR. Of those that did not match, 39 (38%) of prescriptions were found to contain errors. Furthermore, 37 (36%) of patients had an incorrect list of current medications on the EHR. The most common error type on the discharge prescription was drug omission; and on the EHR, wrong drug. Common potentially serious errors were related to unidentified allergies and adverse drug reactions. Conclusions: The EHR can reduce medication errors. However, the EHR should be seen as one of a range of information sources for reconciliation; the primary source being the patient or their carer. Both primary care and hospital clinicians should have read-and-write access to the EHR to reduce errors at care transitions. We recommend further evaluation studies.

Repeatability and reproducibility of macular thickness measurements using fourier domain optical coherence tomography.

Aim: To evaluate repeatability and reproducibility of macular thickness measurements in visually normal eyes using the Topcon 3D OCT-1000. Methods: Phase 1 investigated scan repeatability, the effect of age and pupil dilation. Two groups (6 younger and 6 older participants) had one eye scanned 5 times pre and post- dilation by 1 operator. Phase 2 investigated between-operator, within and between-visit reproducibility. 10 participants had 1 un-dilated eye scanned 3 times on 2 separate visits by 2 operators. Results: Phase 1: No significant difference existed between repeat scans (p=0.75) and no significant difference was found pre- and post-dilation (p=0.54). In the younger group variation was low (95% limits ± 3.62µm) and comparable across all retinal regions. The older group demonstrated greater variation (95% limits ± 7.6µm). Phase 2: For a given retinal location, 95% confidence limits for within-operator, within-visit reproducibility was 5.16µm. This value increased to 5.56µm for the same operator over two visits and to 6.18µm for two operators over two visits. Conclusion: A high level repeatability, close to 6µm, of macular thickness measurement is possible using the 3D OCT- 1000. Measured differences in macular thickness between successive visits that exceed 6µm in pre-presbyopic individuals are therefore likely to reflect actual structural change. OCT measures are more variable in older individuals and it is advisable to take a series of scans so that outliers can be more easily identified.