Head Extension Research Articles

Effects of Head Position on Cerebral Oxygenation and Blood Flow Velocity During Thyroidectomy.

Determining the blood flow through intra and extra-cranial arteries during neck extension may be helpful but is a controversial issue. We aimed to elucidate the changes in cerebral blood flow related to head positioning during thyroid surgery by carotid Doppler examination and regional oxygen saturation variations. Thirty patients were recruited to the study. Patients were positioned with a final position of thyroidectomy consisting a 30° semi Fowler with the extension of neck and head. Values of peak systolic velocity, average velocity, arterial diameter and blood flow volume of the common carotid artery were calculated. Bilateral regional cerebral oxygen saturation were monitored continuously. At the end of the operation, peak systolic velocity, average velocity and blood flowvolume of the common carotid artery decreased significantly compared to the baseline measurement (p<0.001). Both left and right cerebral oximetry measurements showed a significant increase after induction and the increased oxymetric values persisted at the end of the operation (p<0.001). Age, body mass index, surgical duration and anaesthesia duration were found not to be correlated with the changes occurred in the values of peak systolic velocity, average velocity, arterial diameter, blood flow volume of the common carotid artery, left and right regional cerebral oxygen saturation after induction and at the end of surgery. The head and neck extension given for thyroidectomy negatively affect carotid blood flow and cerebral oxygenation gradually and become pronounced especially at the end of surgery. In conclusion, it is important to maintain the cerebral perfusion pressure and cerebral blood flow.

Palatal and lingual augmentation prosthesis for patients with dysphagia and functional problems: A clinical report

This clinical report describes the treatment of a patient with insufficient tongue movement due to bilateral hypoglossal nerve palsy. A palatal augmentation prosthesis and a mandibular intraoral prosthesis (lingual augmentation prosthesis) were provided for this patient to address his functional dysphagia problems. These problems included insufficient oral to pharynx bolus transportation and displacement of the tongue to the right posterior. The 2 prostheses improved these 2 problems and also the head extension posture during swallowing. After insertion of the 2 prostheses, the patient could transport the bolus actively from the oral cavity to the pharynx.

Fixation of 4-part fractures of the proximal humerus: Can we identify radiological criteria that support locking plates or IM nailing? Comparative, retrospective study of 107 cases

IntroductionNo objective criteria exist to help surgeons choose between IM nailing and plate fixation for 4-part fractures of the proximal humerus. The goal of this study was to identify radiological criteria that would make one technique a better choice than the other. Material and methodsThis was a comparative, multicentre, retrospective study of 54 cases of antegrade nailing and 53 cases of plating performed between 1st January 2009 and 31 December 2011 for 4-part fractures of the proximal humerus. All patients had a minimum radiological and clinical follow-up of 18 months. The functional outcomes were evaluated using the weighted Constant score; a poor result was defined as a weighted Constant score<70%. The following radiological criteria were evaluated during the preoperative assessment and at the last follow-up: initial displacement and reduction of humeral head and tuberosities; morphology of the medial column (i.e. calcar comminution, posteromedial hinge, size of metaphyseal head extension); occurrence of avascular necrosis (AVN). ResultsAfter an average follow-up of 42 months, the weighted Constant scores and rate of poor outcomes were 77% and 48% in the nail group and 81% and 38% in the plate group, respectively (ns). The humeral head was reduced into an anatomical position, valgus or varus in 57%, 30% and 13% of cases in the nail group, and 58%, 29% and 13% in the plate group, respectively. The tuberosities healed in an anatomical position in 72% of nail cases and 70% of plate cases (ns). Only the presence of a medial hinge preoperatively had an effect on the functional outcomes in the nail and plate groups: the weighted Constant scores (P=0.05) and rate of poor outcomes (P=0.02) were 82% and 52% in the nail group and 97% and 9% in the plate group, respectively. The complication rates were comparable: the rates of AVN and articular screw penetration were 17% and 11% in the nail group, and 15% and 11% in the plate group, respectively. The surgical revision rate was 18.5% in the nail group and 30% in the plate group. ConclusionIf the medial hinge is preserved, we recommend locking plate fixation. In other cases, either technique can be used as long as the general rules of internal fixation are applied: reduction of the tuberosities, varus correction and stabilization of the calcar area. Level of evidenceIV, retrospective study.

Relationship Between Active Trigger Points and Head/Neck Posture in Patients with Migraine

To investigate the relationship between the presence of active trigger points (TrPs), craniocervical posture, and clinical features (frequency, intensity, and duration) in patients with migraine. A cross-sectional study. Fifty patients with migraine (90% women; age, 34.1 years) participated. Clinical data regarding migraine (frequency, intensity, and duration) were obtained. Trigger points were bilaterally explored in the following muscles: masseter, suboccipital, temporalis (anterior, medium, and posterior fibers), sternocleidomastoid, upper trapezius, and splenius capitis. Eight measures of head and neck posture were obtained from radiographs using the K-Pacs software. Individuals with migraine showed active and latent TrPs in all the muscles, the suboccipital, upper trapezius, sternocleidomastoid, and temporalis muscles being the most affected. The results showed a relationship between the number of active TrPs and several x-ray outcomes, suggesting that the higher number of active TrPs was positively associated with a reduction in cervical lordosis and head extension of the head on the neck. No association between the number of active TrPs and clinical features of migraine was seen. Our study supports the hypothesis that active TrPs are associated with reduced cervical lordosis and head extension in individuals with migraine.

Evaluation of laryngoscopic view, intubation difficulty and sympathetic response during direct laryngoscopy in sniffing position versus simple head extension: a clinical comparative study

Background: Proper position of the head and the neck is important for optimizing laryngoscopic view and for ease of endotracheal intubation.We compared two different positions, sniffing position and simple head extension during direct laryngoscopy on the basis of laryngoscopic view, intubation difficulty and sympathetic response. Methodology: One hundred twenty patients of age group 20-50 years, scheduled for elective surgeries under general anaesthesia were divided into two equal groups in a randomized fashion. In group A (n = 60), sniffing position during laryngoscopy and intubation; and in group B(n =60),simple head extension position during laryngoscopy and intubation. Laryngoscopy view, ease of intubation and hemodynamic parameters were recorded. Results: Demographic data and the different parameters for assessment of difficult airway were similar in both groups. Glottic visualization grade was superior in group A and intubation difficulty score were higher in Group B (P &lt; 0.05), Hemodynamic parameters at different time intervals were comparable. Conclusion: Sniffing position during laryngoscopy was found to be superior to simple head extention position in respect of better glottis visualization and ease of intubation though no difference in sympathetic response to intubation was found.

TrueID: A practical solution to enhance Internet accountability by assigning packets with creditable user identity code

Despite the Internet has been rapidly developed in the past three decades, its intrinsic security mechanism, e.g., IP source address validation and user identification authentication, is still not well addressed. This results in numerous cyber security threats. In order to enhance the Internet accountability and deter potential cyber-attacks, in this paper, we propose TrueID, an IPv6 header extension scheme which can embed hash-based, creditable and undeniable user identity code inside IPv6 packets. We present the system architecture, header’s format and viable implementation approaches with different credibility granularities. Meanwhile, to verify packet credibility and integrity, we design an Autonomous System (AS) level public-key distribution system which can disseminate user’s public keys between allied ASes safely. Also, the prototype experiment has proved that our scheme possesses these features with desirable performance.

AIUM Practice Parameter for the Performance of an Ultrasound Examination of the Neonatal and Infant Spine

AIUM Practice Parameter for the Performance of an Ultrasound Examination of the Neonatal and Infant Spine

AIUM Practice Parameter for the Performance of an Ultrasound Examination of the Neonatal and Infant Spine.

AIUM Practice Parameter for the Performance of an Ultrasound Examination of the Neonatal and Infant Spine.

Finite element model focused on stress distribution in the levator ani muscle during vaginal delivery

Introduction and hypothesisDuring vaginal delivery, the levator ani muscle (LAM) undergoes severe deformation. This stress can lead to stretch-related LAM injuries. The objective of this study was to develop a sophisticated MRI-based model to simulate changes in the LAM during vaginal delivery.MethodsA 3D finite element model of the female pelvic floor and fetal head was developed. The model geometry was based on MRI data from a nulliparous woman and 1-day-old neonate. Material parameters were estimated using uniaxial test data from the literature and by least-square minimization method. The boundary conditions reflected all anatomical constraints and supports. A simulation of vaginal delivery with regard to the cardinal movements of labor was then performed.ResultsThe mean stress values in the iliococcygeus portion of the LAM during fetal head extension were 4.91–7.93 MPa. The highest stress values were induced in the pubovisceral and puborectal LAM portions (mean 27.46 MPa) at the outset of fetal head extension. The last LAM subdivision engaged in the changes in stress was the posteromedial section of the puborectal muscle. The mean stress values were 16.89 MPa at the end of fetal head extension. The LAM was elongated by nearly 2.5 times from its initial resting position.ConclusionsThe cardinal movements of labor significantly affect the subsequent heterogeneous stress distribution in the LAM. The absolute stress values were highest in portions of the muscle that arise from the pubic bone. These areas are at the highest risk for muscle injuries with long-term complications.

Comparison of three different insertion techniques with LMA-Unique™ in adults: results of a randomized trial

BackgroundThe triple airway maneuver insertion technique allowed faster insertion of the LMA. This study compared three different insertion techniques of the laryngeal mask airway-Unique™. MethodsOne hundred and eighty ASA I–II patients aged 18–65 years were included into the study. Patients were randomly allocated to the standard, rotational and triple airway maneuver (triple) group. In the standard group (n=60), the LMA (Laryngeal Mask Airway) was inserted with digital intraoral manipulation. In the triple group (n=60), the LMA was inserted with triple airway maneuver (mouth opening, head extension and jaw thrust). In the rotational group (n=60), LMA was inserted back-to-front, like a Guedel airway. Successful insertion at first attempt, time for successful insertion, fiber optic assessment, airway morbidity and hemodynamic responses were assessed. ResultsSuccessful insertion at the first attempt was 88.3% for the standard, 78.3% for the rotational and 88.3% for the triple group. Overall success rate (defined as successful insertion at first and second attempt) was 93% for the standard, 90% for the rotational and 95% for the triple group. Time for successful insertion was significantly shorter in the triple group (mean [range] 8.63 [5–19]s) compared with the standard (11.78 [6–24]s) and rotational group (11.57 [5–31]s). Fiber optic assessment, airway morbidity and hemodynamic responses were similar in all groups. ConclusionsRotational and triple airway maneuver insertion techniques are acceptable alternatives. Triple airway maneuver technique shows higher overall success rates and allows shorter insertion time for LMA insertion and should therefore be kept in mind for emergent situations.

Hyomental distance in the different head positions and hyomental distance ratio in predicting difficult intubation.

The hyomental distance ratio (HMDR) is the ratio between the hyomental distance (HMD) (the distance between the hyoid bone and the tip of the chin) at the extreme of head extension (HMDe) and the one in the neutral position (HMDn). The objective of the study was to examine the predictive value, sensitivity, and specificity of HMDe, HMDn, and HMDR in predicting difficult endotracheal intubation (DI). A prospective study included 262 patients that underwent elective surgical operations. The following parameters were observed as possible predictors of DI: HMDR, HMDe, HMDn, Mallampati score, and body mass index (BMI). The cut-off points for the DI predictors were HMDe <5.3 cm, HMDn ≤5.5 cm, and HMDR ≤1.2. The assessment that DI existed was made by the anesthesiologist while performing laryngoscopy by applying the Cormack-Lehane classification. DI was present in 13 patients (5%). No significant difference was observed in the frequency of DI with regard to the sex, age, and BMI of the patients. Our research indicated HMDR as the best predictor of DI with a sensitivity of 95.6% and specificity of 69.2%. HMDR can be used in the everyday work of anesthesiologists because HMDR values ≤1.2 may reliably predict DI.

Upper airway modifications in head extension during development

BackgroundOne of the requirements of laryngoscopy is to determine which head position will result in optimal visualization. Our hypothesis was that parameters derived from magnetic resonance imaging (MRI) can help quantify the effect of age on airway modifications due to head extension during development. MethodIn children undergoing planned MRI, additional sequences on the upper airways were performed: one in a near-neutral position, the other with the head extended at 35°. The axis of the face, the pharynx, the larynx, the trachea, and the line of glottic visualization were determined. The following angles were calculated: the Visu-Lar angle, formed by the line of glottic visualization and the laryngeal axis, and the Phar-Lar angle, formed by the pharyngeal and laryngeal axes. ResultsOne hundred and fifty-five patients (1 to 222 months of age [25–145] months) were included and 54% were under general anaesthesia. Age had no effect on the variation in the Visu-Lar angle, which diminished as a function of head extension, nor on the variation in the Phar-Lar angle, which was minimal in the neutral position. During extension, anatomical axes rotated similarly, and the visualization axis rotated the most, followed by the pharyngeal and laryngeal axes. These results were not correlated with general anaesthesia. ConclusionRegardless of age, head extension diminished the Visu-Lar angle, and increased the Phar-Lar angle. This study supports that, as in adults, head extension is probably the key factor for good visualization conditions during laryngoscopy on children, but clinical data is needed to confirm this result.

A Pilot Study of the Head Extension Swallowing Exercise: New Method for Strengthening Swallowing-Related Muscle Activity.

This pilot study examined the effect of a new head extension swallowing exercise (HESE) on submental muscle activity and tongue strength in healthy volunteers. Fifteen young adults (10 females and 5 males) were instructed to extend their head backwards as much as possible, and while watching the ceiling, swallowed their saliva every 10s for a duration of 20min. Twenty-four treatments were performed over 8weeks. The outcome variables evaluated at baseline, 4 and 8weeks of training, and 12-week follow-up included mean and peak submental muscle activation amplitudes during normal and effortful swallowing measured via surface electromyography, and anterior and posterior isometric tongue pressures were measured with the Iowa Oral Performance Instrument. Results indicated that the muscle activation amplitudes during effortful swallowing increased significantly at 4 and 8weeks compared to baseline (p<0.025). However, the increases in amplitudes during normal swallowing were minor (nonsignificant) after 8weeks compared to baseline. The isometric pressures of the tongue tip and the posterior part of the oral tongue were significantly higher at 8weeks compared to baseline (p<0.025). Thus, the 8-week HESE protocol significantly improved suprahyoid muscle activity during effortful swallowing as well as the isometric tongue pressures. The HESE appears effective in exercising and strengthening the suprahyoid muscles and tongue muscles in healthy participants. Although encouraging, these results need to be replicated in clinical trials for testing the therapeutic effects of the HESE in older adults and patients with dysphagia who present with decreased hyolaryngeal elevation.

A comparison of direct laryngoscopic views in different head and neck positions in edentulous patients

ObjectiveProper head and neck positioning is an important factor for successful direct laryngoscopy, and the optimum position in edentulous patients is unclear. We compared direct laryngoscopic views in simple head extension, sniffing, and elevated sniffing positions in edentulous patients. MethodsEighteen adult edentulous patients scheduled for elective surgery were included in the study. After induction of anesthesia, the laryngeal view was assessed under direct laryngoscopy using the percentage of glottic opening (POGO) score in 3 different head and neck positions in a randomized order: simple head extension without a pillow, sniffing position with a pillow of 7 cm, and elevated sniffing position with a pillow of 10 cm. After assessment of the laryngeal views, tracheal intubation was performed. ResultsA significant difference was observed in the laryngeal views assessed at the 3 head positions (P= .001). The POGO scores (mean [SD]) in the sniffing position (78.9% [19.7%]) and elevated sniffing position (72.6% [20.8%]) were significantly improved compared to that with simple head extension (53.8% [25.9%]) (P= .001, respectively). The sniffing position provided the best laryngeal view. The mean POGO scores were higher in the sniffing position than the elevated sniffing position, but no significant difference was observed between these 2 positions (P= .268). ConclusionsThe sniffing and elevated sniffing positions provide better laryngeal views during direct laryngoscopy compared to simple head extension in edentulous patients.

Analyzing the potential benefits ofusingabackpack with non-flexible straps.

Conventional backpack straps are flexible. Due to this flexibility, backpacks freely move on the human back. In this study, a new design of backpacks with non-flexible straps is proposed. The aim of the present research is to demonstrate the possible differences between normal gait and steps while participants carry two different backpacks. In this investigation, 9 healthy male college students were recruited with mean age, height and weight of 24.6 years, 179.6 cm and 76.41 kg, respectively. Each backpack was tested in two different steps. First, the participants were asked to walk on a treadmill, whose velocity was changed from 1.5 m/s to 2.5 m/s, for 15 minutes. Initial velocity was 1.5 m/s and the velocity increased 0.5 m/s in 5 minutes increments. In the next step, they walked for 15 minutes with constant velocity of 3 m/s. Head, neck, and trunk flexion or extension, lateral displacement, and velocity of the subjects during backpack carriage were compared with the obtained values during normal gait, when they walked without carrying a backpack. In addition, the level of discomfort (3 grades: Low, medium, severe) in the neck, shoulder, lumbar, upper and lower leg muscles were investigated by using a modified standardized questionnaire. By wearing the modified design of backpack, trunk flexion decreased while there was no significant (p > 0.05) change in velocity and lateral displacement. According to the questionnaire reports, more than 80% of the participants believed that both backpack discomfort in the neck (anterior side) and upper and lower legs were low. More than 75% of the subjects believed that by using a modified backpack, discomfort decreased for muscles in the neck (posterior), shoulder (posterior) and lumbar muscles. About 60% of both backpack users reported low discomfort in anterior shoulder muscles. Backpacks cause some bad effects on kinematics of gait. In this study, by testing modified backpacks, some improvements were seen, specifically in posture, which may be useful to reduce side effects of backpack carrying.

Airway risk factors for the Miller laryngoscope blade

Study objectiveThe purpose of this study was to analyze previously reported airway risk factors in the performance of Miller laryngoscopy and orotracheal intubation. DesignProspective, observational study. SettingOperating rooms. PatientsA total of 978 American Society of Anesthesiologists I-III adults requiring general orotracheal anesthesia for elective surgery. InterventionsNone. MeasurementsNine previously reported airway risk factors used in predicting difficult laryngoscopy, modified McCormack-Lehane views observed during initial unaided Miller blade laryngoscopy, and number of attempts or need for alternate airway tools to facilitate orotracheal intubation. Main resultsOrotracheal intubation occurred in 941 of 978 (96.2%) patients with the Miller blade, although 8 patients required 3 attempts, with the remaining 37 patients requiring alternate airway tools. There were no failed orotracheal intubations. Multivariable analysis revealed that modified Mallampati class, thyromental distance, and ability to prognath were associated with progressively inferior modified Cormack-Lehane views, whereas modified Mallampati class, height, and head and neck extension were associated with progressive difficulty with orotracheal intubation. ConclusionsThe Miller blade is highly successful in the performance of direct laryngoscopy for orotracheal intubation. These findings suggest that different sets of airway risk factors affect the process of laryngoscopy and orotracheal intubation.

Airtraq, LMA CTrach and Macintosh Laryngoscopes in Tracheal Intubation Training: A Randomized Comparative Manikin Study.

Training students on simulators before allowing their direct contact with patients is well accepted. There is no clinical or manikin-based simulation study in the literature comparing tracheal intubation with Airtraq, laryngeal mask airway (LMA) CTrach and Macintosh laryngoscopes performed by medical students having no prior intubation experience. After obtaining written informed consents, 123 participants were included in the study. The participants were asked to intubate the manikin five times with each device randomly. After all the participants had completed their fifth intubations, the measurements were performed. The primary outcome variables were the first-attempt success rate and the time for a successful intubation, while the secondary outcome variables were to determine the scores of dental trauma, the difficulty visual analogue scale and the optimization manoeuvres. The LMA CTrach group revealed a significantly higher number of intubation attempts. The mean time for a successful intubation was the longest in the LMA CTrach group (17.66±8.22 s, p<0.05). Students defined the Airtraq as the easiest to use and the Macintosh laryngoscope as the most difficult device to use and learn. Dental trauma severity was significantly lower in the Airtraq group than in the other groups (p<0.05), and it was found to be 0 in 81.1% in the Airtraq group. The head extension optimization manoeuvre rate was significantly higher with the Macintosh laryngoscope than with the Airtraq laryngoscope (p<0.05). This study, in which different types of laryngoscopes were compared, revealed that the Airtraq laryngoscope has advantages, such as shorter intubation duration, less additional optimization manoeuvres, less dental trauma intensity and is easier to learn compared with the LMA CTrach and Macintosh laryngoscopes.

Endotracheal tube displacement during head and neck movements. Observational clinical trial

Study ObjectiveMeasure the displacements of endotracheal tube (ETT) tip displacement during head and neck movements. DesignObservational study. SettingEar-nose-throat (ENT) and neurosurgery operating room. PatientsWe performed a maximal head-neck movement trial on 50 adult patients, American Society of Anaesthesiologists 1 or 2. Patients with body mass index >35 kg · m−2, height <150 cm, airway malformations, pulmonary diseases, difficulties in neck flexion or extension, previous ENT surgery or radiotherapy, gastroesophageal reflux, or dental instability were excluded from the study. InterventionsENT and neurosurgery. MeasurementsWe measured the change in distance between the ETT tip and the carina, using a fiberscope through the ETT. ResultsAfter intubation, a wide disparity of tube tip distance to the carina in the neutral position was noted with a median of 5.0 (3.5-7.0) cm. Cephalad tube movement was documented following maximal head and neck extension in 34 (68%) patients and right head rotation in 25 patients (50%). Caudal tube displacement was due to maximal head and neck flexion in 38 patients (76%) and left head rotation in 25 patients (50%). Selective right main bronchus intubation was noted in 2 (4%) patients after maximal head extension. ConclusionMaximal head and neck movements led to unpredictable tube displacements. Proper reassessment of tube positioning after head and neck movement of intubated patients is therefore mandatory.

Cervico-occipital Posture in Women With Migraine: A Case-Control Study.

Case-control study. Previous studies have assessed forward head posture in patients with migraine using photographs. To date, no study has compared postural differences using both radiographs and photographs. To determine the differences in head extension posture between women with migraine and healthy women assessed with radiographic and photographic measures. Thirty-three women (mean ± SD age, 32 ± 11.3 years) with migraine and 33 matched controls (age, 33 ± 12.6 years) participated. Radiographs were used to measure the high cervical angle (HCA), the angle between the most inferior line from the occipital surface to the posterior portion of C1 and the posterior surface of the odontoid process of C2, and the vertical distance between C0 and C1 (C0-C1). Photographs and commercially available software were used to assess the craniovertebral angle (CVA). None of the outcomes differed significantly between women with migraine and control participants. Outcomes for women with migraine were HCA, 66.1° (95% confidence interval [CI]: 64.2°, 68.1°); CVA, 46.1° (95% CI: 45.0°, 47.1°); and C0-C1, 8.5 mm (95% CI: 7.7, 9.2). Outcomes for the control group were HCA, 67.9° (95% CI: 66.5°, 69.3°); CVA, 44.5° (95% CI: 43.2°, 45.7°); and C0-C1, 8.7 mm (95% CI: 7.9, 9.4). Relationships between the frequency (r = -0.42, P = .01, R (2) = 10%) of migraine and the HCA were found. This study demonstrated that women with migraine did not exhibit forward head posture compared to women with no history of headache in either radiographic or photographic postural analysis. However, there was a weak association of the frequency of migraine attacks with a variation in the HCA as assessed by radiographs. Differential diagnosis/symptom prevalence, level 4.

Numerical simulation of the damage evolution in the pelvic floor muscles during childbirth

Several studies have shown that pelvic floor injuries during a vaginal delivery can be considered a significant factor in the development of pelvic floor dysfunction. Such disorders include a group of conditions affecting women like urinary incontinence, pelvic organ prolapse and fecal incontinence. Numerical simulations are valuable tools that are contributing to the clarification of the mechanisms behind pelvic floor disorders. The aim of this work is to propose a mechanical model implemented in the finite element method context to estimate the damage in the pelvic floor muscles by mechanical effects during a vaginal delivery of a fetus in vertex presentation and occipitoanterior position. The constitutive model adopted has already been successfully used in the simulation of childbirth and the structural damage model added has previously been applied to characterize the damage process in biological soft tissues undergoing finite deformations. The constitutive parameters were fit to experimental data available in the literature and the final proposed material model is suitable to estimate the mechanical damage in the pelvic floor muscle during a vaginal delivery.The computational model predicts that even an apparently uneventful vaginal delivery inflicts injuries to the pelvic floor muscles, particularly during the extension of the fetus head, having been obtained more than 10% of damaged fibers. As a clinical evidence, the present work allows to conclude that the puborectalis component of the levator ani muscle is the most prone to damage.