Improper Positioning Research Articles

Perioperative Nerve Injury: A Silent Scream?

Perioperative Nerve Injury: A Silent Scream?

Patient positioning in deep hyperthermia: influences of inaccuracies, signal correction possibilities and optimization potential

In this deep hyperthermia study, the robustness of SAR (specific absorption rate) patterns to patient-position variations is assessed, as well as the possibilities to correct for improper positioning and the benefits of non-standard positions. With a finite element model, the SAR distributions were predicted for ten patients at 33 positions. Position sensitivity is assessed for both SAR-focus steering, i.e. settings based on a calculated focus in a cylindrical patient representation, and HTP (hyperthermia treatment planning)-guided steering, i.e. model-based optimization of the SAR distribution. Position inaccuracies of less than 1 cm do not significantly affect SAR patterns. For SAR-focus steering, the SAR maximum is not always at the desired focus location, especially in the Y (anterior/posterior)- and Z (axial)-directions. For a maximum shift of 5 cm in all directions, both SAR-focus steering and HTP-guided steering are suitable to correct for improper positioning up to the level that none of the investigated positions appears preferable. Current positioning precision is sufficient in the X (right–left)-direction, but precision measurements are needed to reach the desired accuracy in the Y-direction. In the Z-direction, a cranial shift of the applicator is predicted to be beneficial. If the position is known accurately, correction of the treatment setting is possible without loss of heating efficiency. Additionally, no preferable positions exist.

Improved accuracy of computer assisted glenoid implantation in total shoulder arthroplasty: An in-vitro randomized controlled trial

Glenoid replacement is challenging due to the difficult joint exposure and visualization of anatomical reference landmarks. Improper positioning of the glenoid component or inadequate correction of the retroversion using currently available instrumentation may lead to early failure. The objective of this study was to evaluate a computer-assisted technique to achieve a more accurate placement of the glenoid component compared to traditional techniques. Sixteen paired cadaveric shoulders were randomized to either traditional or computer-assisted glenoid implantation. Preoperative planning consisting of CT scanning with 3-dimensional image modeling of the shoulder specimens and intraoperative tracking with real-time feedback provided to the surgeon was employed in the computer-assisted group. A validated, previously published, standardized protocol for tracking the orientation of the glenoid in space using 3 glenoid surface landmarks was employed. All phases of glenoid implantation (initial guide pin insertion, reaming, drilling of the peg holes, and final component implantation) were tracked and recorded by the computer. A post-implantation CT scan was performed in both groups to compare how accurately the implants were placed. The computer-assisted technique was more accurate in achieving the correct version during all phases of glenoid implantation and as measured on the post-implantation CT scan (P < .05). The largest errors with traditional glenoid implantation were observed during drilling and, more so, during reaming. The trend was to overly retrovert the glenoid. Computer assisted navigation results in a more accurate glenoid component placement relative to traditional techniques. Basic Science Study.

Reconstruction of the Orbital Floor With Sheets of Autogenous Iliac Cancellous Bone

Various autografts and synthetic materials such as titanium plates have been used for orbital floor reconstruction; however, no consensus on reconstruction methods has been reached. We have used iliac cancellous bone for this reconstruction with good results. Patients (n = 101) enrolled in this study underwent orbital floor reconstruction of pure blowout fracture with an approximate 1 mm thinned and trimmed iliac cancellous bone without fixation of the graft. The results were assessed by CT; diplopia exceeding an angle of 45 degrees was evaluated as a poor outcome. Postoperatively, diplopia appeared in 15 patients and disappeared in 86 patients. At 6-month follow-up, CT showed that the morphology of the orbit was well maintained and no shedding or improper positioning of the grafted bone was observed in any of the patients. Moreover, CT images demonstrated ossification of the transplanted bone graft. The method encompassing the use of the medulla of the iliac bone has several merits: 1) the graft bone is sufficiently pliable and flexible to fit the gently curving orbital floor; 2) being soft, it is easy to cut. Furthermore, no complication attributable to its fragility is observed at short- and long-term follow-up. The 1 mm thin medullar bone graft derives its robustness from its beamed structure. We consider the medulla of the iliac bone fitting autosomal material for the reconstruction of the orbital floor.

Effects of Dichotically Enhanced Electronic Communication on Crash Risk and Performance during Simulated Driving

In a driving simulator experiment, male and female college students received turn-by-turn driving directions and cognitive tasks while interacting with an experimenter via an audio communication system. In an Enhanced condition (n = 29), lower speech frequencies (containing the speech fundamental frequency) were routed to participants' left ears (with right cerebral-hemisphere processing) and verbal frequencies above the speech fundamental frequency were routed to right ears (with left hemisphere processing). A control group (n = 31) heard unfiltered communications in both ears. Compared to those in the Control condition, participants in the Enhanced condition were significantly less likely to crash and had nonsignificantly lower rates of driving errors (speed infractions, improper lane position, and following distance errors). The results suggest a means of alleviating cognitive load pressure and mitigating crash risk when complex equipment is operated concurrently with two-way electronic communications (cell phone communication while driving, air-to-air and air-to-ground communications, etc.).

Microphone position and speech level sensor

Improper microphone position and speech level on a telephone headset is sensed by comparison of a speech envelope to multiple signal threshold levels. A first threshold is used to determine whether a headset user is talking. A second threshold is used to determine whether a signal level at the microphone is sufficiently strong for proper communication. An indicator is activated when the user is talking and the signal level is too weak. Typically, a weak signal is caused by a mispositioned microphone or a user talking too softly.

Reducing Unplanned Extubations in a Pediatric Intensive Care Unit: A Systematic Approach

Objective. To prospectively determine the rate of unplanned extubations and contributing factors and determine whether a targeted intervention program would be successful in decreasing the rate of unplanned extubations. Design. Prospective, observational study. Setting. A 10-bed Pediatric Intensive Care Unit (PICU). Patients. All intubated pediatric patients during two time periods: September 1, 2000–March 31, 2001 and November 1, 2001–April 30, 2002. Interventions. After determining the rate and causes of unplanned extubation, a program was developed consisting of education and a formalized endotracheal tube taping policy. Data were then collected after implementation of the program. Measurements and Main Results. Prior to the implementation of the program, there were 10 (14.7%) unplanned extubations for a rate of 6.4 unplanned extubations per 100 ventilated days. Of the ten unplanned extubations, reintubation was required in 2 (20%). Inadequate sedation, poor taping, and improper position of the endotracheal tube were the items most frequently cited as causing an unplanned extubation. Following the program, there were two (3.4%) unplanned extubations for 1.0 unplanned extubations per 100 ventilated days. Neither patient required reintubation. There were no significant differences (P > .05) in age, weight, endotracheal tube size, or duration of intubation in the two time periods. However, there was a significant decrease in both the number (P = .03) and the rate (P = .04) of unplanned extubations after the implementation of the quality improvement program. Conclusions. The rate of unplanned extubation in a PICU can be decreased with a quality improvement program that targets the institution's specific needs.

Chronic Dysphagia Secondary To Tracheoesophageal Fistula

Traumatic tracheo-oesophageal fistulas occur secondary to either blunt trauma or open avulsion injury to the neck and thorax. It can occur following prolonged endotracheal tube intubation, as a complication of tracheostomy and improper positioning of tracheostomy tube. Tracheo-oesophageal fistulas following ingested or inhaled foreign bodies are very rare and in majority of these cases they present as an acute condition either with history of recurrent chest infection or aspiration. We present a case where patient present with weight loss and chronic dysphagia few months following ingestion of small denture.

Independent Risk Factors of Catheter-Related Thrombosis (CRT) in Adult Cancer Patients: An Individual Patient-Level Data (IPD) Meta-Analysis of Randomized Clinical Trials and Prospective Cohort Studies

Purpose: Symptomatic catheter-related thrombosis (CRT) complicates roughly 5% of central venous catheter insertions in cancer patients. Recent studies have failed to show a reduction in CRT with routine use of pharmacologic thromboprophylaxis in all patients. We conducted a meta-analysis of individual patient-level data to identify independent, baseline risk factors of CRT that may help to select high-risk patients for prophylaxis.Methods: PubMed, EMBASE, CINAHL, CENTRAL, DARE, Grey literature databases were searched in all languages from 1995–2008. Only prospective studies and randomized controlled trials (RCTs) were included. The primary end-point was objectively confirmed symptomatic and asymptomatic CRT. Multivariate logistic regression analysis of 17 prespecified baseline characteristics was conducted. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated.Results: A total sample of 5636 subjects from 5 RCTs and 7 prospective studies was included in the analysis. Among these subjects, 425 CRT events were observed (8%). In multivariate logistic regression, the use of implanted ports as compared with peripherally implanted central venous catheters (PICC), decreased CRT risk (OR = 0.43; 95% CI, 0.23–0.80). Alternatively, past history of deep vein thrombosis (DVT) (OR = 2.03; 95% CI, 1.05–3.92), subclavian venipuncture insertion technique (OR = 2.16; 95% CI, 1.07–4.34), and improper catheter tip location (OR = 1.92; 95% CI, 1.22–3.02), increased CRT risk.Conclusions: CRT risk is increased with using PICC catheters, previous history of DVT, subclavian venipuncture insertion technique and improper positioning of the catheter tip. These factors may be useful for risk stratifying patients to select those for thromboprophylaxis. Prospective studies are needed to validate these findings.

Bitter sweeteners: tetrazole derivatives of arylsulfonylalcanoids – synthesis, structure and comparative study

Within a research project aimed at the design of new sweeteners, the tetrazole moiety was introduced to arylsulfonylalkanoic acids (ASA) as a bioisostere of the carboxyl group. The crystal structures of four newly synthesized tetrazole derivatives and one intermediate product of the reaction were determined in order to explain the bitter taste of these compounds. Three chiral compounds crystallize as racemic mixtures in centrosymmetric space groups of the monoclinic system, whereas the non-chiral compound, with a higher dipole moment, crystallizes in the polar space group Cc. Intermolecular N-H...N hydrogen bonds between tetrazole moieties were observed in all four structures and are compared with the analogous interactions observed in tetrazole derivatives deposited in the Cambridge Structural Database (CSD). Specifically, the typical N1-H...N4 as well as N1-H...N3 interactions, which are less abundant in the CSD, are described. The formation of the latter interaction type can be hypothetically explained by an asymmetry of pi-electron distribution in the tetrazole rings caused by the crystalline environment. Important features of the crystal architecture are the chains of molecules linked by N-H...N bonds. A possible reason for the lack of a sweet taste of the tetrazoles investigated may be the improper position of the tetrazole H atom, and the mutual orientation of the proton donor and acceptor in their molecules. This orientation does not allow the tetrazoles to interact with the sweet-taste receptor in a way similar to that of ASA. The bitter taste of the investigated compounds needs further study.

Gli3‐deficient mice exhibit cleft palate associated with abnormal tongue development

Palatogenesis depends on appropriate growth, elevation, and fusion of the palatal shelves and aberration in these processes can lead to palatal clefting. We observed a high incidence of palate clefting in mice deficient in Gli3, known for its role as a repressor in the absence of Shh signaling. In contrast with several current mouse models of cleft palate, Meckel's cartilage extension, cranial neural crest migration, palatal shelf proliferation, apoptosis, and key signaling components mediated by Shh, Bmp, Fgf, and Tgfbeta, appeared unaffected in Gli3-/- mice. Palatal clefting in Gli3-/- mice was consistently associated with tongue abnormalities such as failure to flatten and improper positioning, implicating a critical role of Gli3 and normal tongue morphogenesis for timely palatal shelf elevation and joining. Furthermore, Gli3-/- palatal shelves grown in roller cultures without tongue can fuse suggesting that the abnormal tongue is likely an impediment for palatal shelf joining in Gli3-/- mutants.

Electrode Position Scaling in Realistic Laplacian Computation

This note discusses the effects of the electrode position scaling on the realistic Laplacian (RL) computation. It is shown that when the RL is estimated with the help of Tikhonov regularization and the generalized cross-validation (GCV) criterion, improper electrode position scaling may influence the GCV criterion, which results in the decrease of RL precision. We identify what the proper scaling should be, and we provide a closer examination of how the GCV criterion is affected by the electrode position scaling.

Postoperative Alopecia Following Orthognathic Surgery

Postoperative alopecia is a pressure-induced, circumscribed area of occipital hair loss, usually after lengthy operative procedures. Prolonged hair follicle ischemia, a result of constant pressure from improper head positioning, is thought to be causative. Most commonly a reversible condition, it can be quite distressing for a patient. The maxillofacial surgeon must understand the pathophysiology and natural history of the condition to correctly identify it and employ measures to prevent it. Here we report a case of postoperative (pressure) alopecia in a female patient after orthognathic surgery. Report of a Case A 37-year-old female underwent Le Fort I osteotomy, bilateral sagittal split osteotomies, and sliding genioplasty to correct a dentofacial deformity, consisting of vertical maxillary excess, mandibular deficiency, and retrogenia. The patient’s head was positioned in the usual fashion, by first placing a head drape, and then resting it on a foam doughnut. The patient had very long hair that had to be gathered posteriorly into the head drape. The 5-hour surgery progressed without complications using a hypotensive anesthesia technique. Mean arterial blood pressure during the case was 65. The patient was discharged on postoperative day 2. At the 3-week follow-up, the patient complained of a “bald” spot at the occipital region near the vertex of the scalp (Fig 1). Upon further questioning, the patient reported a slight discomfort in this area the preceding 3 weeks, but no swelling or ulceration. The patient was reassured and had resolution of hair loss 6 months later.

Bioengineered Tissues for Urogenital Repair in Children

The most common congenital abnormalities involve the genitourinary system. These include hypospadias, in which the urethral opening develops in an improper position, and bladder exstrophy, in which the bladder develops on the outer surface of the abdomen. Children with these conditions will require immediate and multiple reconstructive surgeries. Currently, reconstruction may be performed with native nonurologic tissues (skin, gastrointestinal segments, or mucosa), homologous tissues from a donor (cadaver or living donor kidney), heterologous tissues or substances (bovine collagen), or artificial materials (silicone, polyurethane, teflon). However, these materials often lead to complications after reconstruction, either because the implanted tissue is rejected, or because inherently different functional parameters cause a mismatch in the system. For example, replacement of bladder tissue with gastrointestinal segments can be problematic due to the opposite ways in which these two tissues handle solutes-urologic tissue normally excretes material, and gastrointestinal tissue generally absorbs the same materials. This mismatched state can lead to metabolic complications as well as infection and other issues. The replacement of lost or deficient urologic tissues with functionally equivalent ones would improve the outcome of reconstructive surgery in the genitourinary system. This goal may soon be attainable with the use of tissue engineering techniques.

Muscle strength analysis of patella resurfacing in total knee arthroplasty

To investigate the influence of patella tracking and thickness for muscle strength after patellar resurfacing in total knee arthroplasty (TKA). Quadriceps muscle strength of 100 cases 134 knees with osteoarthritis were analysed with isokinetic testing and extension lag after patellar resurfacing in TKA. Result was analyzed statistically through T test. Significant decreasing of quadriceps muscle strength and endurance were detected on mal-patellofemoral tracking (61 +/- 24, P <0.01) and improper position of patella prosthesis (56 +/- 33, P < 0.01). Anterior knee pain with patella resurfacing was mainly associated with mal-patellofemoral tracking. Asymptomatic weakness of quadriceps muscle was mainly associated with improper patella thickness.

Research on the Influence that Stop Position of Cerpet Tufting Machineto Yarn Tension and the Method of Elimination Stop Mark

During weaving tufting carpet, the improper stop position of tufting machine will result in stop mark, which influences the carpet quality. In this thesis, through theory analysis and experiment research, the influence rule on the stop position of tufting machine to loop yarn tension and to loop-height has been obtained, and a method of eliminating stop mark by stopping machine in high has been put forward. The technology experiment has proved that when it overlaps partly with high position signal, a fixed position of stopping tufting machine in high has been realized by sending out stop instruction and stopping the tufting machine by a brake cylinder, and the best result of eliminating stop mark has achieved.

Motor Vehicle Crashes Obesity and Seat Belt Use: A Deadly Combination?

Previous studies indicate that compared with lean adults, obese persons are more likely to improperly wear a lap belt across the abdomen. Improper lap belt positioning could result in severe abdominal injuries and a related increase in death. We hypothesized that adult nonobese-belted occupants involved in motor vehicle crashes (MVC) have lower mortality and lower frequency of abdominal injury than obese-belted and obese-nonbelted occupants. A national population-based cohort of adult (>/=16 years) nonobese (body mass index, BMI <30 kg/m) and obese (BMI >/=30 kg/m) MVC occupants included in the National Automotive Sampling System Crashworthiness Data System for 2003 was studied. The study population was divided into nonobese-belted, nonobese-nonbelted, obese-belted, and obese-nonbelted MVC occupants. The primary outcome was 30-day mortality. The secondary outcome was intra-abdominal injury (IAI). Crude odds ratios and 95% confidence intervals were calculated. Multivariate logistic regression analysis was used to adjust estimates for significant occupant, vehicle, and crash-related factors. Occupants (10,656) were in the National Automotive Sampling System-Crashworthiness Data System database for 2003 and 9,313 occupants were eligible for analysis. BMI and seat belt use records were available for 7,459. Lack of seat belt use conferred an increased odds of death and IAI compared with nonbelted occupants for both obese (9.71 [5.08-18.56]) and nonobese (5.26 [3.07-9.03]) occupants. Neither mortality nor IAI was increased in obese-belted occupants compared with nonobese-belted occupants. Proper seat belt use should be encouraged without concern for increases in morbidity or mortality among obese motor vehicle occupants.

The Usefulness of Rectified VEMP

ObjectivesFor a reliable interpretation of left-right difference in Vestibular evoked myogenic potential (VEMP), the amount of sternocleidomastoid muscle (SCM) contraction has to be considered. Therefore, we can ensure that a difference in amplitude between the right and left VEMPs on a patient is due to vestibular abnormality, not due to individual differences of tonic muscle activity, fatigue or improper position. We used rectification to normalize electromyograph (EMG) based on pre-stimulus EMG activity. This study was designed to evaluate and compare the effect of rectification in two conventional ways of SCM contraction.MethodsTwenty-two normal subjects were included. Two methods were employed for SCM contraction in a subject. First, subjects were made to lie flat on their back, lifting the head off the table and turning to the opposite side. Secondly, subjects push with their jaw against the hand-held inflated cuff to generate cuff pressure of 40 mmHg. From the VEMP graphs, amplitude parameters and inter-aural difference ratio (IADR) were analyzed before and after EMG rectification.ResultsBefore the rectification, the average IADR of the first method was not statistically different from that of the second method. The average IADRs from each method decreased in a rectified response, showing significant reduction in asymmetry ratio. The lowest average IADR could be obtained with the combination of both the first method and rectification.ConclusionRectified data show more reliable IADR and may help diagnose some vestibular disorders according to amplitude-associated parameters. The usage of rectification can be maximized with the proper SCM contraction method.

Children sport shoes—A systematic review of current literature

The child's foot is clearly distinct from the adult foot in its functional anatomy and ability to cope with pressure. This requires special considerations in the development of a children's sport shoe. Medical and sport science databases were thoroughly searched for studies pertaining to the anatomy and biomechanics of children's feet during their development. With the data found, a list of requirements for the children's shoe was compiled. Small children should have a sports shoe, which is as flexible as their own foot. The small impact forces during their sports activities make extra cushioning superfluous. During school age the connective tissue gains stability. The growing amount of sports activities, much of which is performed on hard indoor surfaces, enhances the need for cushioning. At the same time there is a growing necessity for adequate mechanical stimuli to help the muscles and bones develop. The strength of the connective tissue and the flexibility of the joints reach adult levels by the age of 15. In small shoes, the displacement of proportions can lead to improper positioning of the flex zone and thereby causing harmful stress on the foot. Cushioning elements are often oversized. Considering the wide range of anatomy in the child's foot, it is advisable to produce children's shoes in different widths. The child's foot differs in anatomy and function from the adult foot. Children sport shoes should meet the child specific requirement.

Tip Position of Long‐Term Central Venous Access Devices Used for Parenteral Nutrition

Venous thrombosis is a potential postplacement complication of a central venous access device (VAD). Improper catheter tip position is a predisposing factor, especially when the device is used to administer parenteral nutrition (PN). American Society for Parenteral and Enteral Nutrition (A.S.P.E.N.) guidelines recommend that a central VAD used for PN be placed with its tip in the superior vena cava (SVC) adjacent to the right atrium (RA). The purpose of this study is to determine the prevalence of improper central VAD tip position and factors associated with malpositioning. All adult patients with a longterm VAD (ie, tunneled central venous catheter, peripherally inserted central catheter [PICC], or implanted port) placed before the current admission who were scheduled to receive PN also received chest x-rays to evaluate position of the catheter tip. Position was determined by a staff radiologist. A catheter with its tip ranging from the middle third of the SVC to the RA was considered acceptable; a catheter with its tip in any other position was considered malpositioned. Subjects with multiple VADs or multiple evaluations for the same catheter had the first placement and last evaluation considered. A logistic regression analysis was used to study the univariable and multivariable associations of these factors with tip malposition. Data were collected for catheters in 124 patients, including 74 tunneled catheters (71 Hickman, 2 Broviac, 1 Groshong), 38 PICCs, and implanted ports. Most of the catheters were placed for (81.9%) or chemotherapy (14.5%). Median catheter duration was 1.6 months at time of evaluation. Of 138 catheters studied, 15.9% (95% confidence interval, 10.2-23.1) were malpositioned at time of evaluation. According to univariable analysis, factors associated with malpositioned catheters included shorter catheter duration (p = .001), greater number of lumens (p = .029), venous entry site on the arm (p <.001) and catheters placed at institutions other than Cleveland Clinic (p = .007). Additionally, PICCs were likely to be malpositioned at time of evaluation compared with other long-term VADs combined (34.2% vs 9.0%; p < .001). A high percentage of long-term VADs improperly positioned for PN in the present study. were more likely to be malpositioned at time of evaluation compared with tunneled catheters and implanted These findings suggest the tip position of long-term should be confirmed before infusing PN.