The effect of nefopam on lactation after caesarean section: a single-blind randomised trial.

BACKGROUND: Nefopam is a centrally acting analgesic which has a theoretical risk of stopping lactation due to its anticholinergic and dopaminergic effects. The aim of this study was to evaluate the effect of nefopam on lactation and to investigate potential adverse effects on newborns. METHODS: Seventy-two women, scheduled to undergo a caesarean delivery under spinal anaesthesia and wanting to breastfeed, were randomised to one of two groups: nefopam (20mg, six hourly) or paracetamol (1g, six hourly). In both groups, postoperative analgesia was supplemented with ketoprofen (50mg, six hourly) in conjunction with intrathecal morphine 0.1mg. The primary outcome was onset of lactation, estimated by weighing the newborns before and after feeding; by maternal perception of breast fullness and based on serum prolactin concentration 48hours postpartum. Secondary outcomes were neonatal adverse effects evaluated by neurobehavioural score at 12, 24, 48, and 72hours after birth. Statistical analyses were performed using Chi-squared, Fisher exact and Student t tests as appropriate. P<0.05 was considered statistically significant. RESULTS: The difference in the weight of the newborn before and after each feed, maternal perception of breast fullness and serum prolactin did not significantly differ between groups. The volume of artificial milk given to newborns of mothers in the nefopam group on days two and three was significantly greater than for the paracetamol group. Neurobehavioural scores were comparable at each time point. CONCLUSION: Nefopam does not appear to delay the onset of lactation or present any clear risk to the newborn.

Three dimensional measurement of minimum joint space width in the knee from stereo radiographs using statistical shape models.

OBJECTIVES: An important measure for the diagnosis and monitoring of knee osteoarthritis is the minimum joint space width (mJSW). This requires accurate alignment of the x-ray beam with the tibial plateau, which may not be accomplished in practice. We investigate the feasibility of a new mJSW measurement method from stereo radiographs using 3D statistical shape models (SSM) and evaluate its sensitivity to changes in the mJSW and its robustness to variations in patient positioning and bone geometry. MATERIALS AND METHODS: A validation study was performed using five cadaver specimens. The actual mJSW was varied and images were acquired with variation in the cadaver positioning. For comparison purposes, the mJSW was also assessed from plain radiographs. To study the influence of SSM model accuracy, the 3D mJSW measurement was repeated with models from the actual bones, obtained from CT scans. RESULTS: The SSM-based measurement method was more robust (consistent output for a wide range of input data/consistent output under varying measurement circumstances) than the conventional 2D method, showing that the 3D reconstruction indeed reduces the influence of patient positioning. However, the SSM-based method showed comparable sensitivity to changes in the mJSW with respect to the conventional method. The CT-based measurement was more accurate than the SSM-based measurement (smallest detectable differences 0.55 mm versus 0. 82 mm, respectively). CONCLUSION: The proposed measurement method is not a substitute for the conventional 2D measurement due to limitations in the SSM model accuracy. However, further improvement of the model accuracy and optimisation technique can be obtained. Combined with the promising options for applications using quantitative information on bone morphology, SSM based 3D reconstructions of natural knees are attractive for further development.Cite this article: E. A. van IJsseldijk, E. R. Valstar, B. C. Stoel, R. G. H. H. Nelissen, N. Baka, R. van't Klooster, B. L. Kaptein. Three dimensional measurement of minimum joint space width in the knee from stereo radiographs using statistical shape models. Bone Joint Res 2016;320-327. DOI: 10.1302/2046-3758.58.2000626.

Respiratory motion estimation in x-ray angiography for improved guidance during coronary interventions.

During percutaneous coronary interventions (PCI) catheters and arteries are visualized by x-ray angiography (XA) sequences, using brief contrast injections to show the coronary arteries. If we could continue visualizing the coronary arteries after the contrast agent passed (thus in non-contrast XA frames), we could potentially lower contrast use, which is advantageous due to the toxicity of the contrast agent. This paper explores the possibility of such visualization in mono-plane XA acquisitions with a special focus on respiratory based coronary artery motion estimation. We use the patient specific coronary artery centerlines from pre-interventional 3D CTA images to project on the XA sequence for artery visualization. To achieve this, a framework for registering the 3D centerlines with the mono-plane 2D + time XA sequences is presented. During the registration the patient specific cardiac and respiratory motion is learned. We investigate several respiratory motion estimation strategies with respect to accuracy, plausibility and ease of use for motion prediction in XA frames with and without contrast. The investigated strategies include diaphragm motion based prediction, and respiratory motion extraction from the guiding catheter tip motion. We furthermore compare translational and rigid respiratory based heart motion. We validated the accuracy of the 2D/3D registration and the respiratory and cardiac motion estimations on XA sequences of 12 interventions. The diaphragm based motion model and the catheter tip derived motion achieved 1.58 mm and 1.83 mm median 2D accuracy, respectively. On a subset of four interventions we evaluated the artery visualization accuracy for non-contrast cases. Both diaphragm, and catheter tip based prediction performed similarly, with about half of the cases providing satisfactory accuracy (median error < 2 mm).

Do prophylactic prostaglandins reduce the transfusion rate at cesarean section in high-order multiple pregnancies?

OBJECTIVE: Cesarean section is the more usual mode of delivery in high-order multiple pregnancy (> or =3). Excessive uterine distension increases the risk of bleeding and the need for transfusion. The aim of this study was to investigate if prophylactic use of prostaglandins at cesarean section for high-order multiple pregnancies reduces blood loss and transfusion requirement based on historic data. STUDY DESIGN: We studied a prospective series of 28 parturients with high-order multiple pregnancy (group 2) who were treated, after clamping the last umbilical cord, with oxytocin (5IU intravenous then 35IU in a 24h infusion) combined with intravenous prostaglandin. A comparable retrospective series of 14 patients (group 1) had been given oxytocin alone at the same dose. Postoperative serum hemoglobin and transfusion rate as well as adverse effects were compared between the two groups. Student's t-test was used to compare continuous variables. Chi square test and Fisher exact test were used to compare categorical variables. RESULTS: The two groups were comparable for anthropometric data and duration of pregnancy. None of the patients in group 2 required red cell transfusion while 21.4% of those in group 1 required transfusion. A significant lower decrease of postoperative haemoglobin is noted in group 2 (P=0.0006). Multivariate analysis using variables significant at univariate analysis and pre-eclampsia confirmed this difference. There were no adverse reactions to treatment. CONCLUSION: In our experience, prophylactic prostaglandin infusion at cesarean section in high-order multiple pregnancy is associated with a lower need for per operative red cell transfusion and a higher postoperative hemoglobin level. This observation merits confirmation in larger studies.

Analgesia after caesarean section: patient-controlled intravenous morphine vs epidural morphine.

In a randomized, double-blind study, conducted in 60 patients after caesarean section, we compared epidural morphine (5 mg) with intravenous morphine patient-controlled analgesia (PCA). Efficacy of pain relief (visual analogue scale), comfort, satisfaction and side-effects were studied. In the PCA group, pain scores were higher (P < 0.005) from the third hour onward. The degree of comfort was similar. Overall satisfaction for the first 24 postoperative hours was higher in the epidural group when assessed on a graded scale from 0 to 10, but equal when assessed using qualitative terms. Haemodynamic and respiratory tolerance were identical without any episodes of respiratory depression or oxygen desaturation in either group. The epidural morphine group showed a higher incidence of pruritus requiring specific treatment (P < 0.005). Nausea was reported to be equal in the two groups. Consumption of morphine was higher in the PCA group. We conclude that epidural morphine analgesia, though of good quality, was associated with more pruritus. Morphine PCA, although producing a lesser degree of analgesia compared to epidural morphine, gave good satisfaction.

Relationship between the shape and density distribution of the femur and its natural frequencies of vibration.

It has been recently suggested that mechanical loads applied at frequencies close to the natural frequencies of bone could enhance bone apposition due to the resonance phenomenon. Other applications of bone modal analysis are also suggested. For the above-mentioned applications, it is important to understand how patient-specific bone shape and density distribution influence the natural frequencies of bones. We used finite element models to study the effects of bone shape and density distribution on the natural frequencies of the femur in free boundary conditions. A statistical shape and appearance model that describes shape and density distribution independently was created, based on a training set of 27 femora. The natural frequencies were then calculated for different shape modes varied around the mean shape while keeping the mean density distribution, for different appearance modes around the mean density distribution while keeping the mean bone shape, and for the 27 training femora. Single shape or appearance modes could cause up to 15% variations in the natural frequencies with certain modes having the greatest impact. For the actual femora, shape and density distribution changed the natural frequencies by up to 38%. First appearance mode that describes the general cortical bone thickness and trabecular bone density had one of the strongest impacts. The first appearance mode could therefore provide a sensitive measure of general bone health and disease progression. Since shape and density could cause large variations in the calculated natural frequencies, patient-specific FE models are needed for accurate estimation of bone natural frequencies.

Oriented Gaussian mixture models for nonrigid 2D/3D coronary artery registration.

2D/3D registration of patient vasculature from preinterventional computed tomography angiography (CTA) to interventional X-ray angiography is of interest to improve guidance in percutaneous coronary interventions. In this paper we present a novel feature based 2D/3D registration framework, that is based on probabilistic point correspondences, and show its usefulness on aligning 3D coronary artery centerlines derived from CTA images with their 2D projection derived from interventional X-ray angiography. The registration framework is an extension of the Gaussian mixture model (GMM) based point-set registration to the 2D/3D setting, with a modified distance metric. We also propose a way to incorporate orientation in the registration, and show its added value for artery registration on patient datasets as well as in simulation experiments. The oriented GMM registration achieved a median accuracy of 1.06 mm, with a convergence rate of 81% for nonrigid vessel centerline registration on 12 patient datasets, using a statistical shape model. The method thereby outperformed the iterative closest point algorithm, the GMM registration without orientation, and two recently published methods on 2D/3D coronary artery registration.

Statistical coronary motion models for 2D+t/3D registration of X-ray coronary angiography and CTA.

Accurate alignment of intra-operative X-ray coronary angiography (XA) and pre-operative cardiac CT angiography (CTA) may improve procedural success rates of minimally invasive coronary interventions for patients with chronic total occlusions. It was previously shown that incorporating patient specific coronary motion extracted from 4D CTA increases the robustness of the alignment. However, pre-operative CTA is often acquired with gating at end-diastole, in which case patient specific motion is not available. For such cases, we investigate the possibility of using population based coronary motion models to provide constraints for the 2D+t/3D registration. We propose a methodology for building statistical motion models of the coronary arteries from a training population of 4D CTA datasets. We compare the 2D+t/3D registration performance of the proposed statistical models with other motion estimates, including the patient specific motion extracted from 4D CTA, the mean motion of a population, the predicted motion based on the cardiac shape. The coronary motion models, constructed on a training set of 150 patients, had a generalization accuracy of 1mm root mean square point-to-point distance. Their 2D+t/3D registration accuracy on one cardiac cycle of 12 monoplane XA sequences was similar to, if not better than, the 4D CTA based motion, irrespective of which respiratory model and which feature based 2D/3D distance metric was used. The resulting model based coronary motion estimate showed good applicability for registration of a subsequent cardiac cycle.

Statistical shape model-based femur kinematics from biplane fluoroscopy.

Studying joint kinematics is of interest to improve prosthesis design and to characterize postoperative motion. State of the art techniques register bones segmented from prior computed tomography or magnetic resonance scans with X-ray fluoroscopic sequences. Elimination of the prior 3D acquisition could potentially lower costs and radiation dose. Therefore, we propose to substitute the segmented bone surface with a statistical shape model based estimate. A dedicated dynamic reconstruction and tracking algorithm was developed estimating the shape based on all frames, and pose per frame. The algorithm minimizes the difference between the projected bone contour and image edges. To increase robustness, we employ a dynamic prior, image features, and prior knowledge about bone edge appearances. This enables tracking and reconstruction from a single initial pose per sequence. We evaluated our method on the distal femur using eight biplane fluoroscopic drop-landing sequences. The proposed dynamic prior and features increased the convergence rate of the reconstruction from 71% to 91%, using a convergence limit of 3 mm. The achieved root mean square point-to-surface accuracy at the converged frames was 1.48 ± 0.41 mm. The resulting tracking precision was 1-1.5 mm, with the largest errors occurring in the rotation around the femoral shaft (about 2.5° precision).

2D-3D shape reconstruction of the distal femur from stereo X-ray imaging using statistical shape models.

Three-dimensional patient specific bone models are required in a range of medical applications, such as pre-operative surgery planning and improved guidance during surgery, modeling and simulation, and in vivo bone motion tracking. Shape reconstruction from a small number of X-ray images is desired as it lowers both the acquisition costs and the radiation dose compared to CT. We propose a method for pose estimation and shape reconstruction of 3D bone surfaces from two (or more) calibrated X-ray images using a statistical shape model (SSM). User interaction is limited to manual initialization of the mean shape. The proposed method combines a 3D distance based objective function with automatic edge selection on a Canny edge map. Landmark-edge correspondences are weighted based on the orientation difference of the projected silhouette and the corresponding image edge. The method was evaluated by rigid pose estimation of ground truth shapes as well as 3D shape estimation using a SSM of the whole femur, from stereo cadaver X-rays, in vivo biplane fluoroscopy image-pairs, and an in vivo biplane fluoroscopic sequence. Ground truth shapes for all experiments were available in the form of CT segmentations. Rigid registration of the ground truth shape to the biplane fluoroscopy achieved sub-millimeter accuracy (0.68mm) measured as root mean squared (RMS) point-to-surface (P2S) distance. The non-rigid reconstruction from the biplane fluoroscopy using the SSM also showed promising results (1.68mm RMS P2S). A feasibility study on one fluoroscopic time series illustrates the potential of the method for motion and shape estimation from fluoroscopic sequences with minimal user interaction.