Forehead Pulse Oximetry: Headband Use Helps Alleviate False Low Readings Likely Related to Venous Pulsation Artifact

Background: This study investigated whether a tensioning headband that applies up to 20 mmHg pressure over a forehead pulse oximetry sensor could improve arterial hemoglobin oxygen saturation reading accuracy in presence of venous pooling and pulsations at the forehead site.

Methods: Healthy volunteers were studied breathing room air in supine and various levels of negative incline (Trendelenburg position) using the forehead sensor with the headband adjusted to its maximum and minimum recommended pressure limits. Saturation readings obtained from the forehead sensor with the subjects supine and the headband in place were used as a baseline to compare the effects of negative incline on reading accuracy when using and not using the headband. Occurrences of false low-saturation readings detected by forehead sensors were compared with those from digit sensors.

Results: No difference was observed between saturation readings obtained from the forehead sensor in supine and negative incline positions when the headband was applied. Forehead sensor readings obtained while subjects were inclined and the headband was not used were significantly lower (P < 0.05) than the supine readings. There was no statistically significant difference between the digit and forehead sensor in reporting false low-saturation readings when the headband was applied, regardless of body incline.     

Quality assessment program in histopathology: a pilot study from Maharashtra

Histopathology reports are important quality assurance tools and evaluation of pathological diagnoses described in them is an integral part of total quality control and quality improvement program. We describe a program based on slide circulation which was aimed at both continuing education to upgrade knowledge and proficiency testing of histopathologists. The performance of the participating pathologists was analyzed and the degree of agreement was also studied. The results showed improvement indicated by rising level of performance in 35.3% of consistent participants and increasing trend in the average score. The degree of agreement was comparatively low (65.29%). The practicability of this program and its acceptability as an EQAS was also investigated.     

Supracondylar Humerus Fractures: Classification Based Treatment Algorithms

Supracondylar humerus fractures are the most common fractures around the elbow in children between 4 and 10 years of age. The treatment of supracondylar humerus fractures can vary from conservative treatment to operative treatment depending on the fracture type. All around the world, the most commonly used classification system is the Wilkins-modified Gartland classification of supracondylar humerus fractures. Currently, the decision to operate or conserve the fracture is taken on basis of this classification system. Non-operative treatment for type I fractures and operative treatment for type III fractures have been well-established in literature. The management of type II supracondylar humerus fracture creates confusion in the minds of numerous orthopaedic surgeons around the world. We have tried addressing this using a classification-based treatment algorithm. Other classification systems like the AO classification, Lagrange and Rigault classification and Bahk classification with special reference to special fracture patterns that require attention and pre-op planning have also been mentioned. It is important to understand that operative management of each supracondylar humerus fracture is unique as regards fixation method and it is important to consider the fracture pattern before internal fixation.     

Reliability of Overcoverage Parameters With Varying Morphologic Pincer Features: Comparison of EOS® and Radiography

Background

Multiple radiographic parameters used for diagnosis and quantification of morphologic pincer features have emerged, but the degree to which pelvic tilt or rotation affects conventional radiography and EOS^® is unknown.

Question/purposes

We asked: (1) What is the reliability of EOS^® and conventional radiography at increasing sizes of morphologic pincer features with varying degrees of tilt and rotation? (2) What is the effect of tilt and rotation on acetabular overcoverage measurements?

Methods

Using a dry cadaveric pelvis, AP conventional radiographs and EOS^® images were taken at intervals of increasing modeled pincer size with 0° to 15° varying tilt and rotation. Lateral center-edge angle, Sharp angle, Tönnis angle, crossover sign, and retroversion index were measured on all images. Statistical analysis was conducted.

Results

The intermodality intraclass correlation coefficients for conventional radiography and EOS^® radiography across all pincer sizes, rotations, and tilts were excellent (0.93–0.98). Crossover sign was in perfect agreement in conventional radiography and EOS^®. Rotation of the hip away from the beam source and/or increased anterior tilt falsely increased all overcoverage parameters except for Tönnis angle. Rotation away from the beam of 10°or greater or anterior tilt of 5° or greater produced a false-positive crossover sign.

Conclusions

EOS^® radiography maintained excellent reliability in comparison to conventional radiography but both were equally vulnerable to the effects of tilt and rotation for quantification of hip parameters used in acetabular overcoverage assessment. A standardized pelvic radiograph ensuring that the pelvis is not excessively tilted or rotated should be used for assessing acetabular overcoverage parameters.     

Does Femoral Rotation Influence Anteroposterior Alpha Angle,Lateral Center-edge Angle,and Medial Proximal Femoral Angle? A Pilot Study

Background

Femoral rotation on AP radiographs affects several parameters used to assess morphologic features of the proximal femur but its effect on femoroacetabular impingement parameters remains unknown.

Question/purposes

We therefore evaluated and characterized the potential effect of femoral rotation on (1) AP alpha angle, (2) lateral-center edge angle (LCEA), and (3) medial proximal femoral angle (MPFA) on AP hip radiographs.

Methods

We took seven AP hip radiographs at intervals of successive femoral rotation on a single dry, cadaveric specimen: 60°, 40°, and 20° internal rotation; 0° neutral/anatomic rotation; and 20°, 40°, and 50° external rotation. The AP alpha angle, LCEA, and MPFA were measured on all radiographs by two independent evaluators.

Results

Within the range of femoral rotation studied, the AP alpha angle ranged from 39° to 62°, the LCEA from 25° to 35°, and the MPFA from 70° to 115°. MPFA and AP alpha angle showed a linear relationship with femoral rotation. Each additional degree of internal rotation produced a reciprocal reduction of the MPFA by 0.36° and the AP alpha angle by 0.18° and vice versa in external rotation. The LCEA, especially within the internal rotation range, showed minimal variation.

Conclusions

These changes in radiographic parameters emphasize the importance of femoral rotation and patient positioning. We recommend radiographs be evaluated for excessive femoral rotation or nonstandardized positioning before interpretation for diagnostic and treatment implications. It may be prudent to repeat radiographs in these circumstances or, when standardized positioning is not feasible, proceed toward advance imaging.     

Glucocorticoid inhibition of neuropathic limb edema and cutaneous neurogenic extravasation

Sciatic nerve section in rats evokes chronic limb edema, pain behavior, and hindpaw hyperalgesia, a syndrome resembling the complex regional pain syndrome type II (CRPS II or causalgia) in man. Glucocorticoids such as methylprednisolone (MP) have been used as analgesic and anti-edematous agents in patients suffering from CRPS, and interestingly these therapeutic effects appear to persist in some patients after stopping the medication. Similar to the CRPS clinical response to glucocorticoids, we now demonstrate that chronic hindpaw edema in the sciatic transection CRPS model is reversed by a continuous infusion of MP (3 mg/kg/day over 21 days), and this anti-edematous effect persists for at least 1 week after discontinuing MP. Furthermore, there is a chronic increase in spontaneous protein extravasation in the hindpaw skin of rats after sciatic transection, similar to the increased protein extravasation observed in the edematous hands of CRPS patients. A 2-week infusion of MP (3 mg/kg/day) reduced spontaneous protein extravasation in the hindpaw skin by 80%. We postulated that increased spontaneous neurogenic extravasation resulted in development of limb edema in both the animal model and the CRPS patient, and that the anti-edematous effects of MP are due to an inhibition of spontaneous extravasation. Additional experiments examined the inhibitory effects of MP infusion on electrically-evoked neurogenic extravasation in the hindpaw skin of normal rats. MP inhibition was dose- and time-dependent, with an ED₅₀ of 1.2 mg/kg/day for a 14-day continuous infusion of MP, and a maximum inhibitory effect requiring 17 days of MP infusion (3 mg/kg/day). MP (3 mg/kg/day for 14 days) also blocked both capsaicin- and SP-evoked neurogenic extravasation, indicating a post-junctional inhibitory effect. Our interpretation is that increased spontaneous neurogenic extravasation in this CRPS model contributed to the development and maintenance of hindpaw edema, and that chronic MP administration dose- and time-dependently blocked neurogenic extravasation at a post-junctional level, thus reversing spontaneous extravasation and limb edema in this model.     

Glucocorticoid inhibition of neuropathic hyperalgesia and spinal Fos expression

Glucocorticoids are used to treat patients suffering from neuropathic pain and complex regional pain syndromes (CRPS). Previously we found that once-daily injections of the glucocorticoid methylprednisolone had no antihyperalgesic effect in the rat sciatic nerve transection model for CRPS, but on the basis of CRPS clinical data, we hypothesized that a continuous infusion of methylprednisolone might prove effective. We further postulated that the antihyperalgesic effects of glucocorticoids were mediated by the inhibition of spinal neuron hyperactivity and by the depletion of substance P or its NK(1) receptor. This study tested the effects of continuously infused methylprednisolone in sciatic nerve-transected rats. Continuous infusion of methylprednisolone (3 mg. kg(-1). d(-1) for 21 days), started after the development of neuropathic hyperalgesia, reversed both heat and mechanical hyperalgesia over 2 wk, and this effect persisted for at least 1 wk after discontinuing methylprednisolone. In addition, continuous methylprednisolone infusion partially reversed nerve injury-evoked Fos expression in the dorsal horns, suggesting that glucocorticoids can inhibit the spinal neuron hyperactivity induced by chronic sciatic nerve transection. Finally, no changes were observed in spinal substance P or NK(1) immunoreactivity after chronic methylprednisolone infusion, suggesting that the depletion of this neuropeptide or its receptor does not contribute to the antihyperalgesic actions of glucocorticoids.     

Sedative but not analgesic alpha2 agonist tolerance is blocked by NMDA receptor and nitric oxide synthase inhibitors

BACKGROUND: Studies show that the sedative and analgesic effects of alpha2 adrenergic agonists decrease over time, which is a form of synaptic plasticity referred to as tolerance. Because both the N-methyl-D-aspartate (NMDA) receptor complex and nitric oxide synthase are pivotal for some forms of synaptic plasticity, their role in tolerance to the hypnotic and analgesic effects of alpha2 agonists was investigated. METHODS: After institutional approval, rats were made tolerant to the hypnotic or analgesic action of an alpha2 agonist, dexmedetomidine. The hypnotic response to dexmedetomidine was assessed by the duration of loss of righting reflex, and the analgesic response to dexmedetomidine was assessed by the tail-flick assay. In separate cohorts, either the NMDA receptors or nitric oxide synthase was antagonized by coadministration of MK-801, ketamine, or NO2-arginine, respectively, during induction of tolerance. In a separate series of experiments, after tolerance was induced, the hypnotic and analgesic responses to dexmedetomidine were assessed in the presence of acutely administered MK-801 or NO2-arginine. RESULTS: Induction of tolerance to the hypnotic effect of dexmedetomidine is blocked by coadministration of MK-801, ketamine, and NO2-arginine. However, after tolerance developed, acute administration of MK-801, ketamine, or NO2-arginine did not prevent the expression of tolerance. Coadministration of MK-801 or NO2-arginine neither prevents the development nor reverses the expression of tolerance to the analgesic action of dexmedetomidine. CONCLUSION: The underlying processes responsible for the development of tolerance to the hypnotic and analgesic actions of systemically administered alpha2 agonists were different, with only the sedative tolerance involving the NMDA receptor and nitric oxide synthase system.