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The index 2014 International Society for the Advancement of Spine Surgery Policy Statement—Minimally Invasive Surgical Sacroiliac Joint Fusion—was generated out of necessity to provide an International Classification of Diseases, Ninth Revision (ICD-9)-based background and emphasize tools to ensure correct diagnosis. A timely ICD-10-based 2016 update provided a granular threshold selection with improved level of evidence and a more robust and relevant database (Appendix Table A1). As procedures and treatment options have evolved, this 2020 update reviews and analyzes the expanding evidence base and provides guidance relating to differences between the lateral and dorsal surgical procedures for minimally invasive surgical sacroiliac joint fusion.

In this letter, a dual-band 8x8 MIMO antenna that operates in the sub-6 GHz spectrum for future 5G multiple-input multiple-output (MIMO) smartphone applications is presented. The design consists of a fully grounded plane with closely spaced orthogonal pairs of antennas placed symmetrically along the long edges and on the corners of the smartphone. The orthogonal pairs are connected by a 7.8 mm short neutral line for mutual coupling reduction at both bands. Each antenna element consists of a folded monopole with dimensions 17.85 x 5mm2 and can operate in 3100-3850 MHz for the low band and 4800-6000 MHz for the high band ([S11] ˂ -10dB). The fabricated antenna prototype is tested and offers good performance in terms of Envelope Correlation Coefficient (ECC), Mean Effective Gain (MEG), total efficiency and channel capacity. Finally, the user effects on the antenna and the Specific Absorption Rate (SAR) are also presented.

Lumbar disc herniation (LDH) is a frequent cause of low back pain and radiculopathy, disability, and diminution in quality of life. While nonsurgical care remains the mainstay of initial treatment, symptoms that persist for prolonged periods of time are well treated with discectomy surgery. A large body of evidence shows that, in patients with unremitting symptoms despite a reasonable period of nonsurgical treatment, discectomy surgery is safe and efficacious. In patients with symptoms lasting greater than 6 weeks, various forms of discectomy (open, microtubular, and endoscopic) are superior to continued nonsurgical treatment. The small but significant proportion of patients with recurrent disc herniation experience less improvement overall than patients who do not experience reherniation after primary discectomy. Lumbar discectomy patients with large annular defects (≥6 mm wide) are at a higher risk for recurrent herniation and revision surgery. Annular closure via a bone-anchored device has been shown to decrease the rate of recurrent disc herniation and associated reoperation in these high-risk patients. After a detailed review of the literature, current clinical evidence supports discectomy (open, microtubular, or endoscopic discectomy) as a medically necessary procedure for the treatment of LDH with radiculopathy in indicated patients. Furthermore, there is new scientific evidence that supports the use of bone-anchored annular closure in patients with large annular defects, who are at greater risk for recurrent disc herniation.

Image guidance (IG) and robotic-assisted (RA) surgery are modern technological advancements that have provided novel ways to perform precise and accurate spinal surgery. These innovations supply real-time, three-dimensional imaging information to aid in instrumentation, decompression, and implant placement. Although nothing can replace the knowledge and expertise of an experienced spine surgeon, these platforms do have the potential to supplement the individual surgeon's capabilities. Specific advantages include more precise pedicle screw placement, minimally invasive surgery with less reliance on intraoperative fluoroscopy, and lower radiation exposure to the surgeon and staff. As these technologies have become more widely adopted over the years, novel uses such as tumor resection have been explored. Disadvantages include the cost of implementing IG and robotics platforms, the initial learning curve for both the surgeon and the staff, and increased patient radiation exposure in scoliosis surgery. Also, given the relatively recent transition of many procedures from inpatient settings to ambulatory surgery centers, access to current devices may be cost prohibitive and not as readily available at some centers. Regarding patient-related outcomes, much further research is warranted. The short-term benefits of minimally invasive surgery often bolster the perioperative and early postoperative outcomes in many retrospective studies on IG and RA surgery. Randomized controlled trials limiting such confounding factors are warranted to definitively show potential independent improvements in patient-related outcomes specifically attributable to IG and RA alone. Nonetheless, irrespective of these current unknowns, it is clear that these technologies have changed the field and the practice of spine surgery. Surgeons should be familiar with the potential benefits and tradeoffs of these platforms when considering adopting IG and robotics in their practices.

Study Design:Systematic review.Objectives:Superiority claims for medical devices are commonly derived from noninferiority trials, but interpretation of such claims can be challenging. This study aimed to ( a) establish the prevalence of noninferiority and superiority designs among spinal device trials, ( b) assess the frequency of post hoc superiority claims from noninferiority studies, and ( c) critically evaluate the risk of bias in claims that could translate to misleading conclusions.Methods:Study bias was assessed using the Cochrane Risk of Bias Tool. The risk of bias for the superiority claim was established based on post hoc hypothesis specification, analysis of the intention-to-treat population, post hoc modification of a priori primary outcomes, and sensitivity analyses.Results:Forty-one studies were identified from 1895 records. Nineteen (46%) were noninferiority trials. Fifteen more (37%) were noninferiority trials with a secondary superiority hypothesis specified a priori. Seven (17%) were superiority trials. Of the 34 noninferiority trials, 14 (41%) made superiority claims. A medium or high risk of bias was related to the superiority claim in 9 of those trials (64%), which was due to the analyzed population, lacking sensitivity analyses, claims not being robust during sensitivity analyses, post hoc hypotheses, or modified endpoints. Only 4 of the 14 (29%) noninferiority studies provided low bias in the superiority claim, compared with 3 of the 5 (60%) superiority trials.Conclusions:Health care decision makers should carefully evaluate the risk of bias in each superiority claim and weigh their conclusions appropriately.

This paper presents the design of a Ka-band reflectarray antenna, intended for LEO-satellite communications, which operates at 27 GHz. The phase tuning mechanism relies on variable size patches capable of achieving a 360° phase range, which enables the incoming wave to be scattered in any specific direction. In particular, the reflectarray antenna, which has a squared-shape of 30 cm each side, is constituted by a 50 × 50 radiating-patch elements, printed on a planar substrate of "Rogers TMM4" material. With a 27.41 dBi directivity, this configuration is able to generate a pencil-beam in perpendicular direction to the reflecting plane.

A machine learning (ML) technique has been used to synthesis a linear millimetre wave (mmWave) phased array antenna by considering the phase-only synthesis approach. For the first time, gradient boosting tree (GBT) is applied to estimate the phase values of a 16-element array antenna to generate different far-field radiation patterns. GBT predicts phases while the amplitude values have been equally set to generate different beam patterns for various 5G mmWave transmission scenarios such as multicast, unicast, broadcast and unmanned aerial vehicle (UAV) applications.

Background: Sympathetic overdrive after apnea and hypopnea events is thought of as a mechanism that increases the risk of cardiovascular morbidity in patients with sleep breathing disorder (SBD). This study questioned if beta-blocker (BB) therapy without CPAP therapy could decrease sympathetic drive in patients with mild SBD. Method: Retrospectively, the medical data of 90 patients with mild SBD, AHI: 5-15 who had PSG in the sleep lab including demographic co-morbidities, medications affecting heart rate variability and central respiratory drive, PSG parameters, average RR interval, low and high-frequency powers (LF, HF) were collected. The two-tailed t-test was applied to the interested data. Results: There were 90 patients (38 females) who had a mild SDB with a mean AHI of 9.37. 24 patients (13 females) were taking BB. In patients on BB therapy compared with patients, not on BB, AHI, PLMS index, arousal index, Oxygen desaturation index, sleep efficiency and total sleep time were not significantly different. The low-frequency power, an indicator of sympathetic activity, was 8180 ms2 vs 13572 ms2in patients on BB vs patients not on BB. (P-value: 0.003, mean of -5392, 95% CI: -8838 to 1947). Conclusion: Our data suggest that beta-blocker therapy without CPAP therapy in patients with mild SBD can significantly reduce sympathetic activity after apneas and hypopneas.

Millimeter wave (mmWave) systems with effective beamforming capability play a key role in fulfilling the high data-rate demands of current and future wireless technologies. Hybrid analog-to-digital beamformers have been identified as a cost-effective and energy-efficient solution towards deploying such systems. Most of the existing hybrid beamforming architectures rely on a subconnected phase shifter network with a large number of antennas. Such approaches, however, cannot fully exploit the advantages of large arrays. On the other hand, the current fully-connected beamformers accommodate only a small number of antennas, which substantially limits their beamforming capabilities. In this article, we present a mmWave hybrid beamformer testbed with a fully-connected network of phase shifters and adjustable attenuators and a large number of antenna elements. To our knowledge, this is the first platform that connects two RF inputs from the baseband to a 16× 8 antenna array, and it operates at 26 GHz with a 2 GHz bandwidth. It provides a wide scanning range of 60°, and the flexibility to control both the phase and the amplitude of the signals between each of the RF chains and antennas. This beamforming platform can be used in both short and long-range communications with linear equivalent isotropically radiated power (EIRP) variation between 10 dBm and 60 dBm. In this article, we present the design, calibration procedures and evaluations of such a complex system as well as discussions on the critical factors to consider for their practical implementation.

By performing the Floquet-mode analysis of a periodic slotted waveguide, a multiple-beam leaky wave antenna is proposed in the millimetre-wave (mmW) band. Considering the direction of surface current lines on the broad/side-walls of the waveguide, the polarization of constructed beams are also controlled. The simulation results are well matched with the initial mathematical analysis.

This paper presents a novel design of trapped microstrip-ridge gap waveguide by using partially filled air gaps in a conventional microstrip-ridge gap waveguide. The proposed method offers an applicable solution to obviate frustrating assembly processes for standalone high-frequency circuits employing the low temperature co-fired ceramics technology which supports buried cavities. To show the practicality of the proposed approach, propagation characteristics of both trapped microstrip and microstrip-ridge gap waveguide are compared first. Then, a right-angle bend is introduced, followed by designing a power divider. These components are used to feed a linear 4-element array antenna. The bandwidth of the proposed array is 13 GHz from $64\sim 76$ GHz and provides the realized gain of over 10 dBi and the total efficiency of about 80% throughout the operational band. The antenna is an appropriate candidate for upper bands of WiGig $( 63.72\sim 70.2)$ and FCC-approved 70 GHz band $( 71\sim 76$ GHz) applications.

The effect of vehicle’s proximity on the radiation pattern when the RADAR’s antenna is mounted on the body of autonomous cars is analysed. Two directional radiation patterns with different specifications are placed at different locations of a realistic car body model. The simulation is performed based on ray-tracing method at 77 GHz, the standard frequency for self-driving applications. It is shown that to obtain a robust RADAR sensor, the antenna radiation pattern is better to have relatively higher gain and lower side-lobe-level (SLL), than narrower halfpower- beamwidth (HPBW) and higher front-to-back (F/B) ratio. Both academia and industry can benefit from this study.

Utilizing the holography theory, a bidirectional wideband leaky wave antenna in the millimetre wave (mmW) band is presented. The antenna includes a printed pattern of continuous metallic strips on an Alumina 99.5% sheet, and a surface wave launcher (SWL) to produce the initial reference waves on the substrate. To achieve a bidirectional radiation pattern, the fundamental TE mode is excited by applying a Vivaldi antenna (as the SWL). The proposed holographic-based leaky wave antenna (HLWA) is fabricated and tested and the measured results are aligned with the simulated ones. The antenna has 22.6% fractional bandwidth with respect to the central frequency of 30 GHz. The interference pattern is designed to generate a 15 deg backward tilted bidirectional radiation pattern with respect to the normal of the hologram sheet. The frequency scanning property of the designed HLWA is also investigated.

Background Short- and mid-term studies have shown the effectiveness of cervical disc arthroplasty (CDA) to treat cervical disc degeneration. Objective To report the 10-yr outcomes of a multicenter experience with cervical arthroplasty for 1- and 2-level pathology. Methods This was a prospective study of patients treated with CDA at 1 or 2 contiguous levels using the Mobi-C® Cervical Disc (Zimmer Biomet). Following completion of the 7-yr Food and Drug Administration postapproval study, follow-up continued to 10 yr for consenting patients at 9 high-enrolling centers. Clinical and radiographic endpoints were collected out to 10 yr. Results At 10 yr, patients continued to have significant improvement over baseline Neck Disability Index (NDI), neck and arm pain, neurologic function, and segmental range of motion (ROM). NDI and pain outcomes at 10 yr were significantly improved from 7 yr. Segmental and global ROM and sagittal alignment also were maintained from 7 to 10 yr. Clinically relevant adjacent segment pathology was not significantly different between 7 and 10 yr. The incidence of motion restricting heterotopic ossification at 10 yr was not significantly different from 7 yr for 1-level (30.7% vs 29.6%) or 2-level (41.7% vs 39.2%) patients. Only 2 subsequent surgeries were reported after 7 yr. Conclusion Our results through 10 yr were comparable to 7-yr outcomes, demonstrating that CDA with Mobi-C continues to be a safe and effective surgical treatment for patients with 1- or 2-level cervical degenerative disc disease.

Purpose: This report documents six-month results of the first 50 patients treated in a prospective, multi-center study of a minimally invasive (MI) sacroiliac (SI) joint fusion system. Patients and Methods: This cohort includes 50 patients who had MI SI joint fusion surgery and completed 6 month follow-up. Average age at baseline was 61.5, 58% were female, and SI joint-related pain duration was ≥2yrs in 54.0% of patients. Visual Analog Scale (VAS) SI joint pain, Oswestry Disability Index (ODI), quality of life and opioid use were assessed preoperatively and at 6 months. Results: At 6 months, mean VAS pain demonstrated a significant reduction from 76.2 at baseline to 35.1 (54% reduction, p

Background: Performing an adequate transforaminal lumbar interbody fusion (TLIF) discectomy requires numerous instrument passes, increasing surgical time and the risk of complications. The purpose of this study was to evaluate the efficacy and efficiency of discectomy and endplate preparation during TLIF using traditional manual instrumentation versus a novel suction discectomy curette. The direct economic benefit with use of the suction discectomy curette is calculated. Methods: Three experienced, spine-fellowship-trained surgeons performed TLIF discectomies on 3 cadaveric specimens from T12 to S1 using either traditional manual discectomy instruments or CONCORDE Clear (Xtool) devices supplemented with manual discectomy instruments. For each level in which a discectomy was performed, the following were measured: elapsed time, number of instrument passes and the number of instrument exchanges, and estimated tissue volume. Results: Transforaminal lumbar interbody fusion discectomy times improved on average 11:32 minutes per level, which equates to an estimated procedural time savings of 15:85 minutes, using 1.4 levels per TLIF, the average number of levels in a large series. Usage of the CONCORDE Clear significantly reduced instrument passes compared to traditional, with a mean of 62.0 for traditional versus 7.1 for CONCORDE Clear, an 8.7-fold improvement. Instrument exchanges showed a 5.9-fold improvement, with means of 26.8 and 4.6, respectively. Wet discectomy tissue volume was measured for each discectomy, with a mean of 5.4 cc for traditional versus 12.9 cc for CONCORDE Clear, a 2.4-fold improvement. Conclusions: This study estimates that, in a typical TLIF procedure, over 15 minutes should be saved by using the CONCORDE Clear l device (a quarter of the time of a traditional discectomy), and by considering the direct cost-benefit associated with this time savings as well as reduced sterilization costs, it is estimated that a hospital could save approximately $1300 in operating room time and sterilization cost with the use of the CONCORDE Clear device in a typical 1-level TLIF procedure.

In the present paper, a photoconductive antenna is designed to work as both pulse-terahertz emitter and receiver. The proposed two-port antenna benefits from polarization diversity with high sensitivity of polarization detection. The antenna electrodes consist of three arms and two gaps that can be excited by laser illumination. An 800 nm wavelength laser beam with output power of 80 mW, 100 MHz repetition rate, and 100 fs laser pulse duration is considered as optical excitation. Each port stimulates a pulse that its polarization is orthogonal to that of the other one according to their arrangement. Along with GaAs as photoconductive substrate beneath the antenna electrodes, an anti-reflection coating of Taconic RF-35 is used for depreciating unwanted terahertz echoes. The simulated results clarify that the proposed antenna shows polarization diversity and also, proper broadband behavior.

The article proposes a novel design for a high gain dual-band millimeter wave (mm-wave) antenna at 26.5 and 36.5 GHz frequency bands using flexible substrate and Co-planar waveguide (CPW) technology. The CPW is able to provide 1.2 GHz bandwidth at 26.5 GHz center frequency and 3 GHz bandwidth at 36.5 GHz with 7.2 and 9.7 dBi gain, respectively. The antenna is composed of a square patch and L-shape slots that are placed symmetrically with distances less than λ/4 (upper band) and the antenna has total dimensions of 16 mm×19 mm. The simulated antenna results are presented in terms of radiation patterns and return loss, and maximum gain as a function of frequency. The performance at millimeter wave and structure flexibility capability are demonstrated that the antenna has potential to implement in the upcoming 5G communication networks.

OBJECTIVE This purpose of this study was to objectively evaluate and assess the efficacy and efficiency of discectomy and endplate preparation during transforaminal lumbar interbody fusion (TLIF) using traditional manual instrumentation versus a novel suction discectomy curette. Transforaminal lumbar interbody fusion is the most widely used approach for lumbar arthrodesis, and its success depends on the ability to achieve fusion. Complete preparation of intervertebral disc space (removal of the nucleus, endplate cartilage, and margin of inner annulus) is the surgical goal. Performing an adequate discectomy requires numerous instrument passes, increasing surgical time and the risk of complications. METHODS Four experienced spinal surgeons performed transforaminal discectomies from T-12 to S-1 on 5 whole-body cadavers. Each level (n = 26) was randomly assigned to either a control group using traditional instruments (12 levels) or to a suction curette group (14 levels). The time required to perform the discectomy and the number of passes through the annulus were recorded. Motion segments were dissected and analyzed by digital photogrammetric analysis. The intervertebral disc and the discectomy cross-sectional areas were measured on both superior and inferior images of each dissected surgical level. Areas were divided into 4 quadrants based on a midsagittal and midcoronal axis and analyzed for regional efficiency. In addition, a cross-sectional area of bony endplate (the area still covered with cartilage) and an area of endplate perforation were evaluated. RESULTS There was no significant difference in surgical time between the techniques (7:51 ± 2:43 minutes in the manual discectomy [MD] group and 7:06 ± 3:33 minutes in the suction curette discectomy [SD] group). There were significantly fewer (p < 0.01) instrument passes in the SD group (13 passes) compared with the MD group (43 passes). For both techniques, the amount of disc removed depended upon the anatomical region, with the posterior-contralateral side having the least amount of disc material removed. There was significantly less (p < 0.01) disc material removed in the MD group (38%) compared with the SD group (48%). The amount of disc material removed was significantly more (p < 0.05) in each quadrant when comparing the SD and MD groups, with the anterior regions showing the largest difference. For both techniques, the preparation of the endplate within the discectomy area resulted in a mostly cartilaginous interface (50% MD, 48% SD); a smaller amount of bony interface area (31% MD, 38% SD); and a smaller amount of perforation to the interface area (19% MD, 13% SD). There were no significant differences between the groups in terms of endplate preparation. CONCLUSIONS The improved discectomy observed with the suction curette device could potentially improve the clinical fusion rate.

Study design Prospective, multicenter, single-blind, randomized, controlled clinical study. Objective To investigate outcomes associated with repairing the anulus fibrosus after lumbar discectomy for the surgical management of herniated nucleus pulposus. Summary of background data In patients undergoing discectomy, the incidence of reherniation ranges from 10% to 15%. Repair of the anulus fibrosus defect after lumbar discectomy may decrease the incidence of recurrent herniation for these patients. Methods A total of 750 patients were treated for herniated lumbar discs and randomly assigned in a 2:1 ratio to discectomy with the Xclose Tissue Repair System (Anulex Technologies, Minnetonka, MN) for anular repair (n = 500) or discectomy without anular repair (n = 250). Patient self-reported measures included visual analogue scales for leg and back pain, Oswestry Disability Index, and Short Form-12 Health Survey. Adverse events and subsequent reherniation surgical procedures were documented. Preoperative outcome measures were compared with follow-up visits at 2 weeks, 6 months, 1 year, and 2 years. Results Patient symptoms were improved after surgery in an equivalent manner in both study groups. In the overall study analysis, the rate of reherniation surgery was lower for Xclose patients at all follow-up time points, but these differences were not statistically significant. In patients with predominant leg pain, there was a significant reduction in reherniation risk at 3 and 6 months postoperation for patients receiving Xclose. A positive reduction was maintained through 2 years, with a clinically relevant risk reduction of 45%, although not statistically significant. Safety was demonstrated with similar improvements in patient outcomes and no difference in reported adverse events. Conclusion Without a safe and effective method for closing the anulus fibrosus after discectomy, current practice has been to leave the anulus in a compromised state. This multicenter randomized study demonstrated that, while not statistically significant, anular repair reduced the need for subsequent reherniation surgery while retaining the benefits of discectomy with no increased risk for patients. Level of evidence 1.

Cheng et al[1][1] have discussed using a dynamic posterior stabilization device to treat asymmetric collapse of an artificial disc in the coronal plane. Although this may correct the radiographic coronal-plane abnormality, there are significant biomechanical considerations to be kept in mind. When

Study design A prospective, randomized, multicenter Food and Drug Administration Investigation Device Exemption study using total disc replacement as surgical treatment of degenerative disc disease at 1 or 2 contiguous levels of the cervical spine. Objective To evaluate the safety and effectiveness of total disc replacement at single or 2 contiguous levels through 48 months of follow-up. Summary of background data Cervical total disc replacement has been shown to be a safe and effective alternative to anterior cervical discectomy and fusion at 24 months. Its motion-preserving capabilities may avoid accelerating adjacent segment pathology and thereby lower the rate of associated complications. Methods Patients were randomized in a 2:1 ratio (total disc replacement [TDR]: anterior cervical discectomy and fusion [ACDF]) at 24 sites. Ultimately, 164 patients received TDR at 1 level and 225 patients received TDR at 2 contiguous levels. An additional 24 patients (15 one-level, 9 two-level) were treated with TDR as training cases.Outcome measures included neck disability index, visual analogue scale neck and arm pain, Short Form 12-item Health Survey (SF-12) Mental Composite Score (MCS) and Physical Composite Score (PCS), range of motion, major complication rates, and secondary surgery rates. Patients received follow-up examinations at regular intervals through 4 years after surgery. Results Preoperative characteristics were statistically similar for the 1- and 2-level patient groups. Four-year follow-up rates were 83.1% (1-level) and 89.0% (2-level). There was no statistically significant difference between 1- and 2-level TDR groups for all clinical outcome measures. Both TDR groups experienced significant improvement at each follow-up when compared with preoperative scores. One case of migration was reported in the 2-level TDR group. Conclusion A 4-year post hoc comparison of 1- and 2-level TDR patients concurrently enrolled in a 24-center, Food and Drug Administration Investigation Device Exemption clinical trial indicated no statistical differences between groups in clinical outcomes, overall complication rates, and subsequent surgery rates. Level of evidence 1.

In this paper, a novel microstrip array antenna to achieve some specific contoured beam is presented. The proposed antenna produces three directional main beams which is a consequence of its particular layout. The antenna is suggested to be mounted on High Altitude Platforms (HAPs) to provide the desirable coverage (e.g. three separated islands). Using developed software, enables us to obtain the footprint of antenna on the ground. Furthermore, a study on channel capacity enhancement, employing the proposed antenna is carried out which clarify the profit of using this contoured beam antenna.

In this paper, using a specific developed MoM code results in the modal behavior (based on Theory of Characteristic Modes) of two different shape dipole antennas: A simple cylindrical wire dipole antenna and a flat metal plate one, These two simple antennas are instances for our new proposed approach to make two antennas equal from the frequency behavior point of view. By making equal the modal behavior of these two antennas we claim that they became same from frequency behavior point of view and the input impedance of structures is confirmed our claim.

Background Minimally invasive percutaneous pedicle screw instrumentation methods may increase the need for intraoperative fluoroscopy, resulting in excessive radiation exposure for the patient, surgeon, and support staff. Electromagnetic field (EMF)-based navigation may aid more accurate placement of percutaneous pedicle screws while reducing fluoroscopic exposure. We compared the accuracy, time of insertion, and radiation exposure of EMF with traditional fluoroscopic percutaneous pedicle screw placement. Methods Minimally invasive pedicle screw placement in T8 to S1 pedicles of eight fresh-frozen human cadaveric torsos was guided with EMF or standard fluoroscopy. Set-up, insertion, and fluoroscopic times and radiation exposure and accuracy (measured with post-procedural computed tomography) were analyzed in each group. Results Sixty-two pedicle screws were placed under fluoroscopic guidance and 60 under EMF guidance. Ideal trajectories were achieved more frequently with EMF over all segments (62.7% vs. 40%; p = 0.01). Greatest EMF accuracy was achieved in the lumbar spine, with significant improvements in both ideal trajectory and reduction of pedicle breaches over fluoroscopically guided placement (64.9% vs. 40%, p = 0.03, and 16.2% vs. 42.5%, p = 0.01, respectively). Fluoroscopy time was reduced 77% with the use of EMF (22 s vs. 5 s per level; p

Blood pressure measurements frequently guide management in critical care. Direct readings, commonly from a major artery, are considered to be the gold standard. Because arterial cannulation is associated with risks, alternative noninvasive blood pressure (NIBP) measurements are routinely used. However, the accuracy of NIBP determinations in overweight patients in the outpatient setting is variable, and little is known about critically ill patients. This prospective, observational study was performed to compare direct intra-arterial blood pressure (IABP) with NIBP measurements obtained using auscultatory and oscillometric methods in overweight patients admitted to our medical intensive care unit. Adult critically ill patients with a body mass index (BMI) of 25 kg/m2 or greater and a functional arterial line (assessed using the rapid flush test) were enrolled in the study. IABP measurements were compared with those obtained noninvasively. A calibrated aneroid manometer (auscultatory technique) with arm cuffs compatible with arm sizes and a NIBP monitor (oscillometric technique) were used for NIBP measurements. Agreement between methods was assessed using Bland-Altman analysis. Fifty-four patients (23 males) with a mean (± standard error) age of 57 ± 3 years were studied. The mean BMI was 34.0 ± 1.4 kg/m2. Mean arm circumference was 32 ± 0.6 cm. IABP readings were obtained from the radial artery in all patients. Only eight patients were receiving vasoactive medications. Mean overall biases for the auscultatory and oscillometric techniques were 4.1 ± 1.9 and -8.0 ± 1.7 mmHg, respectively (P < 0.0001), with wide limits of agreement. The overestimation of blood pressure using the auscultatory technique was more important in patients with a BMI of 30 kg/m2 or greater. In hypertensive patients both NIBP methods underestimated blood pressure as determined using direct IABP measurement. Oscillometric blood pressure measurements underestimated IABP readings regardless of patient BMI. Auscultatory measurements were also inaccurate, tending to underestimate systolic blood pressure and overestimate mean arterial and diastolic blood pressure. NIBP can be inaccurate among overweight critically ill patients and lead to erroneous interpretations of blood pressure.