Novel Cast-saw Alarm System Reduces Blade-to-Skin Contact in a Pediatric Upper Extremity Model.

PURPOSE: To determine the effectiveness of a novel cast-saw alarm system in minimizing the number and duration of cast-saw blade-to-skin contacts. METHODS: Twenty orthopaedic residents removed a pair of long-arm casts applied to instrumented pediatric upper extremity models. The model and cast-saw were instrumented to detect blade to "skin" contact at a rate of 600 Hz. Each resident performed cast removal with and without the use of a cast-saw alarm, the order of which was randomized. Eleven additional "new" cast-saw users then removed pairs of casts, without and then with the cast alarm, to evaluate what effect the alarm would have on preventing blade-to-skin contact in users with no previous cast-saw experience. The number and duration of cast-saw touches were then evaluated. Statistical significance was determined paired 1-sided students t tests (number of touches). RESULTS: For the residents (n=20), the total number of blade-to-skin contacts was 233. One hundred eighty-one blade-to-skin contacts without the alarm and 52 with the alarm (71% reduction) (t(19)=-3.42, P=0.001), averaging 6.45 more blade-to-skin contacts per cast without the alarm. The median blade-to-skin contact duration was 0.166 seconds without the alarm and 0.087 seconds with the alarm. This was a 48% reduction in contact time (P=0.073). For the inexperienced users (n=11), the total number of blade-to-skin contacts was 356, 324 blade-to-skin contacts without the alarm and 32 with the alarm (90% reduction) (t(10)=-2.78, P=0.009), averaging 26.5 more blade-to-skin contacts without the alarm. The median blade-to-skin contact duration for the novice was 0.313 seconds without the alarm and 0.1 seconds with the alarm (68% reduction). Contact time was reduced in both groups but failed to reach statistical significance. However, alarm use significantly reduced the number of touches of >0.5 seconds duration (62 vs. 3) in the novice group, P=0.0176. Blade-to-skin contact of >0.5 seconds were felt to represent touches that were more likely to result in thermal injury to a living patient. CONCLUSION: Blade-to-skin contact can be reduced with the use of a cast-saw alarm. These effects appear most amplified in users with little prior cast-saw experience. LEVEL OF EVIDENCE: Not applicable.

Sagittal Plane Deformities in Children with SMA2 following Posterior Spinal Instrumentation.

This is a retrospective radiographic review to assess post-operative sagittal plane deformities in patients with Spinal Muscular Atrophy type 2 that had been treated with posterior spinal instrumentation. Thirty-two patients with a history of either spinal fusion (N = 20) or growing rods (N = 12) were identified with an average of 7.6 (2.1-16.6) years post-operative follow-up. Forty percent (13/32) of the patients were identified as having obvious "tucked chin" (N = 4), "tipped trunk" (N = 9), or both (N = 3). Sacral incidence was the only parameter that was statistically significant change between pre-operative or immediate post-operative measurements (66.9° vs. 55.2° p = 0.03). However, at final follow-up, the post-operative thoracic kyphosis had decreased over time in those that developed a subsequent sagittal deformity (24.2°) whereas it increased in those that did not (44.7°, p = 0.008). This decrease in thoracic kyphosis throughout the instrumented levels, resulted in a greater lordotic imbalance (30.4° vs. 5.6°, p = 0.001) throughout the instrumented levels in the group that developed the subsequent cervical or pelvic sagittal deformities. In conclusion, sagittal plane deformities commonly develop outside the instrumented levels in children with SMA type 2 following posterior spinal instrumentation and may be the result of lordotic imbalance that occurs through continued anterior growth following posterior instrumentation.

Most High-Intensity Transient Signals Are Not Associated With Specific Surgical Maneuvers.

BACKGROUND: Mortality after congenital heart defect surgery has dropped dramatically in the last few decades. Current research on long-term outcomes has focused on preventing secondary neurological sequelae, for which embolic burden is suspected. In children, little is known of the correlation between specific surgical maneuvers and embolic burden. Transcranial Doppler ultrasound is highly useful for detecting emboli but has not been widely used with infants and children. METHODS: Bilateral middle cerebral artery blood flow was continuously monitored from sternal incision to chest closure in 20 infants undergoing congenital heart defect repair or palliative surgery. Embolus counts for specific maneuvers were recorded using widely accepted criteria for identifying emboli via high-intensity transient signals (HITS). RESULTS: An average of only 13% of all HITS detected during an operation were correlated with any of the surgical maneuvers of interest. The highest mean number of HITS associated with a specific maneuver occurred during cross-clamp removal. Cross-clamp placement also had elevated HITS counts that significantly differed from other maneuvers. CONCLUSIONS: In this study of infants undergoing cardiac surgery with cardiopulmonary bypass, the great majority of HITS detected are not definitively associated with a specific subset of surgical maneuvers. Among the measured maneuvers, removal of the aortic cross-clamp was associated with the greatest occurrence of HITS. Future recommended research efforts include identifying and confirming other sources for emboli and longitudinal outcome studies to determine if limiting embolic burden affects long-term neurological outcomes.

Measuring Hemodynamic Changes in the Ophthalmic Artery During Applied Force for Noninvasive Intracranial Pressure Monitoring: Test Results in a Porcine Model.

Possible traumatic brain injury victims would greatly benefit from a handheld, noninvasive intracranial pressure (ICP) monitoring tool, which a medic could operate in a remote area. Such a device would also benefit the transport of injured soldiers during en route medical care and critical care air transport. This study demonstrates the use of noninvasive blood flow measurements in the eye by ultrasound as a proxy for ICP. ICP was artificially raised in a porcine model and resultant blood flow change in the ophthalmic artery was measured. In addition, the ultrasound transducer itself was used to compress the eye further altering ophthalmic hemodynamics. Blood flow velocities at a range of applied forces and ICP were compared. It was found that 3.25 N of force applied to the cornea was sufficient to produce significant changes in ophthalmic artery blood dynamics regardless of the ICP value. Specifically, the change in resistivity index (RI) and pulsatility index (PI) as force was applied to the cornea correlated with ICP levels. In multiple animal experiments, the magnitude of PI/RI percent change was inversely related to differences in ICP. Force applied to the cornea at baseline ICP resulted in a 15% increase in PI/RI. Results indicate that as ICP increases, the percent change in PI/RI while force is applied decreases. The consistency of data collected indicates that a trend line developed with this data and from similar experiments could be used as a predictive measurement of ICP.