Autoadjusted versus fixed CPAP for obstructive sleep apnoea: a multicentre, randomised equivalence trial.

BACKGROUND: The obstructive sleep apnoea syndrome (OSAS) is conventionally treated by continuous positive airway pressure set at a fixed level (fCPAP). Automatic mask pressure adjustment (autoCPAP) is increasingly used during home therapy. We investigated whether autoCPAP is equivalent to fCPAP in improving sleepiness in patients with OSAS in the long-term. METHODS: In this multicentre equivalence trial, 208 patients with OSAS, with median Epworth sleepiness score (ESS) 13, apnoea/hypopnoea index 48.4/hour, were randomised to treatment with autoCPAP (5-15 mbar) or fCPAP (pressure set at the 90th percentile applied by autoCPAP during 2-4 weeks adaptation). Coprimary outcomes were changes in subjective and objective sleepiness from baseline to 2 years after treatment. Equivalence ranges were ±2 points in ESS and ±3 min sleep resistance time evaluated by recording responses to light signals. RESULTS: At 2 years, in the intention to treat analysis, the reduction in sleepiness versus pretreatment baseline was similar in patients using autoCPAP (n=113, mean ESS-change -6.3, 95% CI -7.1 to -5.5; sleep resistance time +8.3 min, +6.9 to +9.7) and fCPAP (n=95, mean ESS-change -6.2, 95% CI -7.0 to -5.3; sleep resistance time +6.3 min, +4.7 to +7.8). The 95% CI of difference in ESS-reduction between autoCPAP and fCPAP was -0.9 to +1.4 and the 95% CI of difference in increase in sleep resistance time was -2.6 to +1.0 min. Blood pressure reduction and OSAS-related costs were similar between groups. CONCLUSIONS: AutoCPAP and fCPAP are equivalent within prespecified ranges in improving subjective and objective sleepiness in patients with OSAS over the course of 2 years. Costs of these treatments are similar. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov NCT00280800.

The 3dMD photogrammetric photo system in cranio-maxillofacial surgery: Validation of interexaminer variations and perceptions.

BACKGROUND: Three-dimensional photography of the face is increasingly used to overcome the downsides of conventional photography or anthropometry regarding reliable evaluation. However, the precision of such a system has to be validated before it can be implemented for clinical use. MATERIAL AND METHODS: Eight people were photographed with the 3dMDface system using lighting from sets of 2 × 4 compact fluorescent lights in a clinical photography room without natural light sources. Two different operators then individually, and without interaction, marked 27 different anatomical landmarks using the 3dMD Patient software. During this process, the operators were fully blinded against each other. The purpose of the study was to determine the repeatability and accuracy of the system when used by different operators and at different times. The 3D differentiation was analyzed using mixed ANOVA with person as the random factor, and operator, repetition, and landmark as the fixed factors. The ANOVA was followed by a Ryan-Einot-Gabriel-Welsch F post-hoc test for landmarks. RESULTS: Statistical analysis grouped the landmarks into three subgroups: high precision, medium precision and low precision. CONCLUSIONS: Virtual 3D models derived from the 3dMDface system not only provide a high level of technical precision but also of intra- and interobserver reliability regarding landmark identification. However, some of the classical landmarks are not reliable when it comes to virtual models; these are generally landmarks that examiners of real patients would tend to identify using palpation of underlying bony structures, such as the soft gonion.

[Modern technologies in cranio-maxillofacial surgery]. / Moderne Technologien in der Mund-, Kiefer- und Gesichtschirurgie.

Modern technologies are influencing medicine everyday. The oral and maxillofacial surgery meet the worlds from medicine and dentistry. So technologies from both fields are utilized. This article provides an overview about technologies in clinical use, which are typical for the specialty. Their principles and indications are described as well as benefits and limitations. Based on Cone Beam Computed Tomography image fusion and mirroring techniques are explained as well as patient specific models and implants, template guided and free surgical navigation with and without intraoperative three-dimensional imaging. An overall assessment reveals further need of research regarding indications and patient benefit.

Les technologies modernes influencent la médecine chaque jour. La chirurgie orale et maxillofaciale sont à disposition tant de la médecine que de la dentisterie, d'où un partage des technologies. Cet article a pour but de revoir les technologies typiques de la chirurgie orale et maxillofaciale chirurgie utilisées en clinique. Leurs principes et indications sont décrites, de même que leurs bénéfices et leurs limitations. Les scanners à faisceau conique fournissent des modèles spécifiques aux patients permettant la fabrication d'implants. Ils procurent aussi une imagerie tridimensionnelle qui peut être utile en dehors ou au cous d'une opération. Il apparaît qu'il existe encore aujourd'hui un besoin de recherche en ce qui concerne les indications de l'imagerie à faisceau conique et son bénéfice pour le malade.

Evaluation of two dental registration-splint techniques for surgical navigation in cranio-maxillofacial surgery.

BACKGROUND: Surgical navigation requires precise registration of the pre-operative image dataset to the patient in the operation theatre. Different marker-based and marker-free registration techniques are available, each of them with advantages and disadvantages regarding precision and clinical handling. In this model study, the precision of two dental splint techniques for marker-based registration is analyzed. MATERIALS AND METHODS: A synthetic full-size human skull was registered with its cone beam computed tomography dataset using (a) a dentally-mounted "rapid" occlusal splint with five titanium screws directly attached to the splint, (b) an "extender", a dentally-mounted occlusal splint with similar fiducials fixed to an extension of the splint. The target registration error was measured for 170 landmarks distributed over the viscero- and neurocranium in 10 repeats per splint type using the Vector Vision2 (BrainLAB AG, Heimstetten, Germany) navigation system. Statistical and graphical evaluations were performed per anatomical region. RESULTS: In the periorbital region, the rapid splint, with an average deviation of 1.50 mm (SD = 0.439) showed greater accuracy than the extender with 1.76 mm (SD = 0.525). The viscerocranial results for both splints were similar (extender 1.84 mm, SD = 0.559, rapid occlusal splint 1.86 mm, SD = 0.686). In the cranial vault region, registration with the extender (2.33 mm, SD = 0.685) proved to be more precise than with the rapid splint (2.86 mm, SD = 0.929). CONCLUSIONS: Due to the more compact dimension of the rapid occlusal splint, errors close to the splint were smaller compared to the extender technique. The advantage of greater distances between the registration fiducials on the extender is particularly important in areas such as the orbital roof, the cranial vault, and the lateral skull base.

Craniofacial landmarks in young children: how reliable are measurements based on 3-dimensional imaging?

INTRODUCTION: Different approaches for 3-dimensional (3D) data acquisition of the facial surface are common nowadays. Meticulous evaluation has proven their level of precision and accuracy. However, the question remains as to which level of craniofacial landmarks, especially in young children, are reliable if identified in 3D images. Potential sources of error, aside from the systems technology itself, need to be identified and addressed. Reliable and unreliable landmarks have to be identified. MATERIALS AND METHODS: The 3dMDface System was used in a clinical setting to evaluate the intraobserver repeatability of 27 craniofacial landmarks in 7 young children between 6 and 18 months of age with a total of 1134 measurements. RESULTS: The handling of the system was mostly unproblematic. The mean 3D repeatability error was 0.82 mm, with a range of 0.26 mm to 2.40 mm, depending on the landmark. Single landmarks that have been shown to be relatively imprecise in 3D analysis could still provide highly accurate data if only 1 of the 3 spatial planes was relevant. There were no statistical differences from 1 patient to another. CONCLUSIONS: Reliability in craniofacial measurements can be achieved by such 3D soft-tissue imaging techniques as the 3dMDface System, but one must always be aware that the degree of precision is strictly dependent on the landmark and axis in question.For further clinical investigations, the degree of reliability for each landmark evaluated must be addressed and taken into account.

The Reliability of a Three-Dimensional Photo System- (3dMDface-) Based Evaluation of the Face in Cleft Lip Infants.

Ample data exists about the high precision of three-dimensional (3D) scanning devices and their data acquisition of the facial surface. However, a question remains regarding which facial landmarks are reliable if identified in 3D images taken under clinical circumstances. Sources of error to be addressed could be technical, user dependent, or patient respectively anatomy related. Based on clinical 3D photos taken with the 3dMDface system, the intra observer repeatability of 27 facial landmarks in six cleft lip (CL) infants and one non-CL infant was evaluated based on a total of over 1,100 measurements. Data acquisition was sometimes challenging but successful in all patients. The mean error was 0.86 mm, with a range of 0.39 mm (Exocanthion) to 2.21 mm (soft gonion). Typically, landmarks provided a small mean error but still showed quite a high variance in measurements, for example, exocanthion from 0.04 mm to 0.93 mm. Vice versa, relatively imprecise landmarks still provide accurate data regarding specific spatial planes. One must be aware of the fact that the degree of precision is dependent on landmarks and spatial planes in question. In clinical investigations, the degree of reliability for landmarks evaluated should be taken into account. Additional reliability can be achieved via multiple measuring.

The influence of involuntary facial movements on craniofacial anthropometry: a survey using a three-dimensional photographic system.

In the modern anthropometry of complex structures, such as the face, different technical approaches for acquisition of three-dimensional data have become increasingly more common. Results of meticulous evaluations have shown high degrees of precision and accuracy under both ideal and clinical circumstances. However, the question remains as to which level of accuracy is adequate to meet clinical needs. Apart from the measuring technique itself, potential sources of error must be identified and dealt with. Subjects' involuntary facial movements can potentially influence clinical reliability. The 3dMDface™ system was used clinically to investigate the influence of involuntary facial movements. Other factors of influence were systematically excluded. The mean technical error of the system (0.09mm) was investigated in a previous study and taken into account for interpretation of the data. The handling of the system was straightforward for both acquisition and analysis of data. Including technical error and the influence of involuntary facial movements, the mean global error was 0.41mm (range 0-3.3). Taking into account the technical error of the system known from the previous study, involuntary facial movements account for a mean error of 0.32mm. This range of involuntary facial movements clearly exceeds the known technical error of the three-dimensional photographic system used. Given this finding, future research should shift its focus from the analysis of the technical aspects of such systems to other influential factors.

Point-to-point registration with mandibulo-maxillary splint in open and closed jaw position. Evaluation of registration accuracy for computer-aided surgery of the mandible.

INTRODUCTION: Computer navigation plays an increasingly important role in craniomaxillofacial surgery. The difficulties in computer navigation at the craniomaxillofacial site lie in the accurate transmission of the dataset to the operating room. This study investigates the accuracy of the dental-splint registration method for the skull, midface, and mandible. MATERIAL AND METHODS: A synthetic human skull model was prepared with landmarks and scanned with cone beam computer tomography (CBCT). Two registration splints fixed the mandible against the viscerocranium in two different positions (closed vs. open). The target registration error was computed in all 278 landmarks spread over the entire skull and mandible in 10 repeated measurements using the VectorVision(2) (BrainLAB Inc., Feldkirchen, Germany) navigation system. RESULTS: If registered in the closed position an average precision of 2.07 mm with a standard deviation (SD) of 0.78 mm was computed for all landmarks distributed over the whole skull. Registration in the open position resulted in an average precision of 1.53 mm (SD=0.55 mm). For single landmarks the precision decreases linearly with distance from the reference markers. The longer the three-dimensional distance between the registration points, the more precise the computer navigation is, mainly in the most posterior area of the cranium. CONCLUSION: Our findings in the cranium are comparable with those of other studies. Artificial fixation of the lower jaw via splint seems to introduce no additional error. The registration points should be as far apart from each other as possible during navigation with the splint.

Precise screw positioning at the mandibular angle: computer assisted versus template coded.

BACKGROUND: Buried intraoral devices for distraction osteogenesis in mandibular deformities have numerous advantages, but success depends on the precise positioning of these devices. Although most centers nowadays use template-guided techniques for precise positioning, computer navigation has been described as a promising technique. Surgical navigation during device placement could become a viable method because it affords certainty in defining a device position. METHODS: A clinical situation was simulated by means of mounting a mandible model inside a phantom head. Screws were positioned according to a preoperative plan through transoral and transbuccal approaches, with both template-coded and freehand computer navigation. RESULTS: With template-coded navigation, the medium deviation from the planned position was 0.63 mm (range, 0.00-1.24 mm). With commercial freehand surgical computer navigation, the medium deviation was significantly higher at 0.98 mm (range, 0.00-3.13 mm). CONCLUSIONS: Computer-assisted surgery can provide a high level of accuracy in the region of the mandibular angle where precision is crucial for buried intraoral distraction devices. However, template-coded guidance does provide a significantly higher level of accuracy and therefore represents the gold standard.

3-Dimensional imaging for lower third molars: is there an implication for surgical removal?

PURPOSE: Surgical removal of impacted third molars may be the most frequent procedure in oral surgery. Damage to the inferior alveolar nerve (IAN) is a typical complication of the procedure, with incidence rates reported at 1% to 22%. The aim of this study was to identify factors that lead to a higher risk of IAN impairment after surgery. MATERIALS AND METHODS: In total 515 surgical third molar removals with 3-dimensional (3D) imaging before surgical removal were retrospectively evaluated for IAN impairment, in addition to 3D imaging signs that were supposed predictors for postoperative IAN disturbance. Influence of each predictor was evaluated in univariate and multivariate analyses and reported as odds ratio (OR) and 95% confidence interval (CI). RESULTS: The overall IAN impairment rate in this study was 9.4%. Univariate analysis showed narrowing of the IAN canal (OR, 4.95; P < .0001), direct contact between the IAN and the root (OR, 5.05; P = .0008), fully formed roots (OR, 4.36; P = .045), an IAN lingual course with (OR, 6.64; P = .0013) and without (OR, 2.72; P = .007) perforation of the cortical plate, and an intraroot (OR, 9.96; P = .003) position of the IAN as predictors of postoperative IAN impairment. Multivariate analysis showed narrowing of the IAN canal (adjusted OR, 3.69; 95% CI, 1.88 to 7.22; P = .0001) and direct contact (adjusted OR, 3.10; 95% CI, 1.15 to 8.33; P = .025) to be the strongest independent predictors. CONCLUSION: Three-dimensional imaging is useful for predicting the risk of postoperative IAN impairment before surgical removal of impacted lower third molars. The low IAN impairment rate seen in this study-compared with similar selected study groups in the literature of the era before 3D imaging-indicates that the availability of 3D information is actually decreasing the risk for IAN impairment after lower third molar removal.

Anatomy of impacted lower third molars evaluated by computerized tomography: is there an indication for 3-dimensional imaging?

OBJECTIVE: Surgical removal of impacted third molar is one of the most frequent procedures in oral surgery. Today 3-dimensional (3D) imaging is occasionally used. The aim of this study was to describe and estimate the frequencies of anatomic variations of lower third molars in patients with panoramic findings at high risk for inferior alveolar nerve (IAN) injury. STUDY DESIGN: The investigators designed and implemented a retrospective cases series study with a study population composed of patients presenting with an impacted lower third molar with projection of the tooth over the full width of the IAN in panoramic radiograph and, therefore, 3D imaging before a planned surgical removal. Spatial relationship to the IAN, type of angulation, root configuration and maturation were primary study variables. Descriptive statistics were computed for all variables. RESULTS: A total of 707 wisdom teeth in 472 patients (54% female, 46% male) were evaluated. A close relationship to the IAN was seen in 69.7%, and in 45.1% the diameter of the mandibular canal was reduced. In 52.8% the IAN was vestibular and in 37.3% lingual to the roots; there were 9.9% with an inter- or intraroot course. Most teeth had 1 or 2 roots (86.7%), but 13.3% had ≥3 roots. Mesial angulation was the main type (40.2%), followed by vertical (29%), horizontal (13.9%), distal (10.2%), and transverse (6.8%) positions. CONCLUSION: Based on the range of variations in the course of the nerve and the number of roots the authors recommend 3D imaging before surgical removal of a lower third molar that shows signs of a close relationship to the IAN.

Surgical navigation in cranio-maxillofacial surgery: an evaluation on a child with a cranio-facio-orbital tumour.

Surgical navigation, though well-established, is often associated with extra effort for both patient and surgeon, and with additional exposure to radiation as a result of the necessary extra imaging. Osteoblastoma is a benign bone tumour, malignant transformation of which is rare but possible, and so resection is indicated. The orbit with surrounding structures is a challenging region for accurate three-dimensional reconstruction. A virtual plan based on the patient's mirrored anatomy realised by intraoperative navigation can assist in achieving perfect results. An 8-year-old boy presented with a huge osteoblastoma of the frontal and temporal skull. The tumour had extracranial and intracranial parts, and reached into the orbital roof and the sphenoid and ethmoid bones. The ethmoid sinus was involved, the eye was displaced, and he had functional problems. Virtual planning and navigation were prepared without the need for any additional imaging. The tumour was resected through a coronal approach, and immediately reconstructed with an autologous calvarial split graft, designed and positioned under navigation with a preoperative plan that was based on the mirrored healthy side. Surgical navigation based on a virtual plan can achieve symmetrical results, particularly when dealing with complex three-dimensional anatomy. Navigation does not necessarily mean additional procedures or imaging. We think that virtual planning and navigation are useful for selected cases.

Registration for computer-navigated surgery in edentulous patients: a problem-based decision concept.

BACKGROUND: Surgical navigation is a commonly used tool in cranio-maxillofacial surgery. Registration is the key element for precision, and a number of studies have shown different techniques to be accurate. Nonetheless, uncertainty surrounds the special situation in edentulous patients and a practical approach to what can be a challenging problem. MATERIALS AND METHODS: Four registration strategies for the Brainlab VectorVision(2) system are presented for surgical navigation of edentulous patients: three landmark-based, point-to-point techniques and one surface-based matching strategy are evaluated. RESULTS: The methods described differ in overall accuracy as well as in the region covered. In general, the more time-consuming and invasive the technique, the more precise it is. The non-invasive techniques are less precise, and they cover only small regions with sufficient accuracy. CONCLUSIONS: Taking into account which type of accuracy is clinically relevant and that the whole skull does not always need to be covered with the greatest possible accuracy, all the described techniques have their indications. The simpler and less invasive techniques can spare time, decrease costs, and harm patient. A decision tree is presented to the reader.

Misjudgments at the mandibular angle: freehand versus computer-assisted screw positioning.

BACKGROUND: Distraction osteogenesis is a well known and frequently described technique in mandibular deformities. Buried intraoral devices have numerous advantages, but success hinges on precise positioning of the implants. Although computer navigation has repeatedly been described for craniofacial applications, research on navigating the mandibular region is scarce. Navigating the device placement for a mandibular distractor could become a viable method for distraction osteogenesis because of the possibility of certainty in achieving a defined device position. MATERIALS AND METHODS: A clinical situation was simulated by a mandible model mounted inside a phantom head. The screws were positioned according to a virtual plan through transoral and transbuccal approaches, with and without navigation. RESULTS: Without navigation, the mean deviation from the planned position was 4.9 mm (range, 0.9-10.7 mm), with a clear tendency to position the screws in the easy-to-access regions. With navigation, the mean deviation was significantly lower at 1.5 mm (range, 0.1-3.4 mm). CONCLUSIONS: Computer-assisted surgery can provide a high level of accuracy in the region of the mandibular angle, where precision is crucial for buried intraoral distraction devices.

Formation of pseudoaneurysm after aortic valve replacement without previous endocarditis: a case-control study.

BACKGROUND: The aim of this study was to identify the predisposing factors for pseudoaneurysm formation after aortic valve replacement without previous endocarditis. METHODS: Echocardiography was used to identify patients. Parameters with influence on the occurrence of pseudoaneurysms were analyzed, and the odds ratio for the influence of the type of valve was estimated. The chi2 goodness-of-fit test was used to analyze whether location or underlying etiology was associated with an accumulated occurrence of a pseudoaneurysm. Fisher's exact test was used to assess a possible relation between the occurrence of a pseudoaneurysm after composite graft implantation and etiology or location. RESULTS: Patients treated with composite grafts had a 27-fold increased risk for developing pseudoaneurysms (psiMH=27; 95% confidence interval, 1.61-454.19) in comparison with aortic valve replacement only. There was a significant difference for the probability of different etiologies to occur (P=.032), with Stanford type A aortic dissection and aortic regurgitation being the most often occurring pathologies. Significant associations between the use of a composite graft and both the underlying etiology (P=.002) and the location of the pseudoaneurysm (P=.04) was found. Furthermore, patients with composite grafts had larger diameters of the aortic root compared with patients with aortic valve replacement only (P=.03). Neither the diameter of the annulus of the aortic valve (95% confidence interval, 0.89-1.32; P=.41) nor the diameter of the ascending aorta (95% confidence interval, 0.27-1.97; P=.54) had any influence on pseudoaneurysm formation. CONCLUSIONS: The underlying disorder, determining the surgical procedure, influences the risk for the development of pseudoaneurysms in patients without previous endocarditis. The location of most pseudoaneurysms at the level of the aortic root may be a consequence of its larger diameter.

Precision and accuracy of the 3dMD photogrammetric system in craniomaxillofacial application.

BACKGROUND: In modern anthropometry of such complex structures as the face, three-dimensional scanning techniques have become more and more common. Before establishing them as a criterion standard, however, meticulous evaluation of their precision and accuracy under both ideal and clinical circumstances is essential. Potential sources of error need to be identified and addressed. MATERIALS AND METHODS: Under ideal circumstances, a phantom is used to examine the precision and accuracy of the 3dMD system. A clinical setting is simulated by varying different parameters such as angle, distance, and system reregistration, as well as data evaluation under different levels of magnification. RESULTS: The handling of the system was unproblematic in matters of data acquisition and data analysis. It was very reliable, with a mean global error of 0.2 mm (range, 0.1-0.5 mm) for mannequin head measurements. Neither the position of the head nor that of the camera influenced these parameters. New referencing of the system did not influence precision and accuracy. CONCLUSIONS: The precision and accuracy of the tested system are more than sufficient for clinical needs and greater than those of other methods, such as direct anthropometry and two-dimensional photography. The evaluated system can be recommended for evaluation and documentation of the facial surface and could offer new opportunities in reconstructive, orthognathic, and craniofacial surgery.

A novel operator-independent algorithm for cardiac output measurements based on three-dimensional transoesophageal colour Doppler echocardiography.

AIMS: Cardiac output (CO) measurements from three-dimensional (3D) trans-mitral Doppler echocardiography are prone to error as manual selection of the region of interest (i.e. the site of measurement) is required. We newly developed an automated, user-independent algorithm to select the site of colour Doppler CO measurement. We aimed to validate this new method by benchmarking it against thermodilution, the current gold standard for CO measurements. METHODS AND RESULTS: Transoesophageal colour 3D Doppler echocardiographic studies were obtained from 15 patients who also had received a pulmonary catheter for invasive CO measurements. Trans-mitral flow was determined using a novel operator-independent algorithm to automatically select the optimal site of measurement. The operator-independent CO measurements were referenced against thermodilution. A good correlation was found between operator-independent Doppler flow computations and thermodilution with a mean bias of 0.09 L/min, standard deviation of bias 1.3 L/min, and a 26% error (2 SD/mean CO). Mean CO was 4.94 L/min (range 3.10-7.10 L/min). CONCLUSION: Our findings demonstrate that CO computation from transoesophageal colour 3D Doppler echo can be automated concerning the site of velocity measurement. Our operator-independent algorithm provides an objective and reproducible alternative to thermodilution.