Comparison of massive and emergency transfusion prediction scoring systems after trauma with a new Bleeding Risk Index score applied in-flight

BACKGROUND

Assessment of blood consumption (ABC), shock index (SI), and Revised Trauma Score (RTS) are used to estimate the need for blood transfusion and triage. We compared Bleeding Risk Index (BRI) score calculated with trauma patient noninvasive vital signs and hypothesized that prehospital BRI has better performance compared with ABC, RTS, and SI for predicting the need for emergent and massive transfusion (MT).

METHODS

We analyzed 2-year in-flight data from adult trauma patients transported directly to a Level I trauma center via helicopter. The BRI scores 0 to 1 were derived from continuous features of photoplethymographic and electrocardiographic waveforms, oximetry values, blood pressure trends. The ABC, RTS, and SI were calculated using admission data. The area under the receiver operating characteristic curve (AUROC) with 95% confidence interval (CI) was calculated for predictions of critical administration threshold (CAT, ≥3 units of blood in the first hour) or MT (≥10 units of blood in the first 24 hours). DeLong's method was used to compare AUROCs for different scoring systems. p < 0.05 was considered statistically significant.

RESULTS

Among 1,396 patients, age was 46.5 ± 20.1 years (SD), 67.1% were male. The MT rate was 3.2% and CAT was 7.6%, most (92.8%) were blunt injury. Mortality was 6.6%. Scene arrival to hospital time was 35.3 ± (10.5) minutes. The BRI prediction of MT with AUROC 0.92 (95% CI, 0.89-0.95) was significantly better than ABC, SI, or RTS (AUROCs = 0.80, 0.83, 0.78, respectively; 95% CIs 0.73-0.87, 0.76-0.90, 0.71-0.85, respectively). The BRI prediction of CAT had an AUROC of 0.91 (95% CI, 0.86-0.94), which was significantly better than ABC (AUROC, 077; 95% CI, 0.73-0.82) or RTS (AUROC, 0.79; 95% CI, 0.74-0.83) and better than SI (AUROC, 0.85; 95% CI, 0.80-0.89). The BRI score threshold for optimal prediction of CAT was 0.25 and for MT was 0.28.

CONCLUSION

The autonomous continuous noninvasive patient vital signs-based BRI score performs better than ABC, RTS, and SI predictions of MT and CAT. Bleeding Risk Index does not require additional data entry or expert interpretation.

LEVEL OF EVIDENCE

Prognostic test, level III.

Impact of trauma centre capacity and volume on the mortality risk of incoming new admissions

INTRODUCTION

Trauma centre capacity and surge volume may affect decisions on where to transport a critically injured patient and whether to bypass the closest facility. Our hypothesis was that overcrowding and high patient acuity would contribute to increase the mortality risk for incoming admissions.

METHODS

For a 6-year period, we merged and cross-correlated our institutional trauma registry with a database on Trauma Resuscitation Unit (TRU) patient admissions, movement and discharges, with average capacity of 12 trauma bays. The outcomes of overall hospital and 24 hours mortality for new trauma admissions (NEW) were assessed by multivariate logistic regression.

RESULTS

There were 42 003 (mean=7000/year) admissions having complete data sets, with 36 354 (87%) patients who were primary trauma admissions, age ≥18 and survival ≥15 min. In the logistic regression model for the entire cohort, NEW admission hospital mortality was only associated with NEW admission age and prehospital Glasgow Coma Scale (GCS) and Shock Index (SI) (all p<0.05). When TRU occupancy reached ≥16 patients, the factors associated with increased NEW admission hospital mortality were existing patients (TRU >1 hour) with SI ≥0.9, recent admissions (TRU ≤1 hour) with age ≥65, NEW admission age and prehospital GCS and SI (all p<0.05).

CONCLUSION

The mortality of incoming patients is not impacted by routine trauma centre overcapacity. In conditions of severe overcrowding, the number of admitted patients with shock physiology and a recent surge of elderly/debilitated patients may influence the mortality risk of a new trauma admission.

Blood Transfusion Indicators Following Trauma in the Non-Massively Bleeding Patient

BACKGROUND

Establishing transfusion guidelines during trauma resuscitation is challenging. Our objective was to evaluate indications for transfusion in trauma patients who emergently received ≤2 units of red blood cells (RBC) during the first hour of resuscitation.

METHODS

A single center retrospective study included non-massively bleeding trauma patients stratified into 2 groups: 1) with a clinical indication for transfusion and 2) with no indication for transfusion. Admission vital signs (VS), injury severity score (ISS), shock index, and laboratory values were compared between the two groups using the Wilcoxon rank-sum test.

RESULTS

Among 111 non-massively bleeding trauma patients, 40 presented no indication for transfusion. All patients presented similar ISS and VS. The 71 patients presenting with an indication for transfusion had higher bicarbonate (22.6 vs 20.8) and lower lactate levels (4.7 v 6.6) (p<0.05).

CONCLUSION

Lactate and bicarbonate blood levels may be potential indicators for RBC transfusion need during trauma resuscitation in non-massively bleeding patients.

Repeat lactate level predicts mortality better than rate of clearance

BACKGROUND

Lactate clearance has been developed into a marker of resuscitation in trauma, but no study has compared the predictive power of the various clearance calculations. Our objective was to determine which method of calculating lactate clearance best predicted 24-hour and in-hospital mortality after injury.

STUDY DESIGN

Retrospective chart review of patients admitted to a Level-1 trauma center directly from the scene of injury from 2010 to 2013 who survived >15min, had an elevated lactate at admission (≥3mmol/L), followed by another measurement within 24h of admission. Lactate clearance was calculated using five models: actual value of the repeat level, absolute clearance, relative clearance, absolute rate, and relative rate. Models were compared using the areas under the respective receiver operating curves (AUCs), with an endpoint of death at 24h and in-hospital mortality.

RESULTS

3910 patients had an elevated admission lactate concentration on admission (mean=5.6±3.0mmol/L) followed by a second measurement (2.7±1.8mmol/L). Repeat absolute measurement best predicted 24-hour (AUC=0.85, 95% CI: 0.84-0.86) and in-hospital death (AUC=0.77; 95% CI, 0.76-0.78). Relative clearance was the best model of lactate clearance (AUC=0.77, 95% CI: 0.75-0.78 and AUC=0.705, 95% CI: 0.69-72, respectively) (p<0.0001 for each). A sensitivity analysis using a range of initial lactate measures yielded similar results.

CONCLUSIONS

The absolute value of the repeat lactate measurement had the greatest ability to predict mortality in injured patients undergoing resuscitation.

Advanced Visualization Platform for Surgical Operating Room Coordination: Distributed Video Board System

One of the major challenges for day-of-surgery operating room coordination is accurate and timely situation awareness. Distributed and secure real-time status information is key to addressing these challenges. This article reports on the design and implementation of a passive status monitoring system in a 19-room surgical suite of a major academic medical center. Key design requirements considered included integrated real-time operating room status display, access control, security, and network impact. The system used live operating room video images and patient vital signs obtained through monitors to automatically update events and operating room status. Images were presented on a “need-to-know” basis, and access was controlled by identification badge authorization. The system delivered reliable real-time operating room images and status with acceptable network impact. Operating room status was visualized at 4 separate locations and was used continuously by clinicians and operating room service providers to coordinate operating room activities.

Trends of Hemoglobin Oximetry: Do They Help Predict Blood Transfusion During Trauma Patient Resuscitation?

BACKGROUND

A noninvasive decision support tool for emergency transfusion would benefit triage and resuscitation. We tested whether 15 minutes of continuous pulse oximetry-derived hemoglobin measurements (SpHb) predict emergency blood transfusion better than conventional oximetry, vital signs, and invasive point-of-admission (POA) laboratory testing. We hypothesized that the trends in noninvasive SpHb features monitored for 15 minutes predict emergency transfusion better than pulse oximetry, shock index (SI = heart rate/systolic blood pressure), or routine POA laboratory measures.

METHODS

We enrolled direct trauma patient admissions ≥18 years with prehospital SI ≥0.62, collected vital signs (continuous SpHb and conventional pulse oximetry, heart rate, and blood pressure) for 15 minutes after admission, and recorded transfusion (packed red blood cells [pRBCs]) within 1 to 3, 1 to 6, and 1 to 12 hours of admission. One blood sample was drawn during the first 15 minutes. The laboratory Hb was compared with its corresponding SpHb reading for numerical, clinical, and prediction difference. Ten prediction models for transfusion, including combinations of prehospital vital signs, SpHb, conventional oximetry, and routine POA, were selected by stepwise logistic regression. Predictions were compared via area under the receiver operating characteristic curve by the DeLong method.

RESULTS

A total of 677 trauma patients were enrolled in the study. The prediction performance of the models, including POA laboratory values and SI (and the need for blood pressure), was better than those without POA values or SI. In predicting pRBC 1- to 3-hour transfusion, adding SpHb features (receiver operating characteristic curve [ROC] = 0.65; 95% confidence interval [CI], 0.53-0.77) does not improve ROC from the base model (ROC = 0.64; 95% CI, 0.52-0.76) with P = 0.48. Adding POA laboratory Hb features (ROC = 0.72; 95% CI, 0.60-0.84) also does not improve prediction performance (P = 0.18). Other POA laboratory testing predicted emergency blood use with ROC of 0.88 (95% CI, 0.81-0.96), significantly better than the use of SpHb (P = 0.00084) and laboratory Hb (P = 0.0068).

CONCLUSIONS

SpHb added no benefit over conventional oximetry to predict urgent pRBC transfusion for trauma patients. Both models containing POA laboratory test features performed better at predicting pRBC use than prehospital SI, the current best noninvasive vital signs transfusion predictor.

Computer Modelling Using Prehospital Vitals Predicts Transfusion and Mortality

OBJECTIVE

Test computer-assisted modeling techniques using prehospital vital signs of injured patients to predict emergency transfusion requirements, number of intensive care days, and mortality, compared to vital signs alone.

METHODS

This single-center retrospective analysis of 17,988 trauma patients used vital signs data collected between 2006 and 2012 to predict which patients would receive transfusion, require 3 or more days of intensive care, or die. Standard transmitted prehospital vital signs (heart rate, blood pressure, shock index, and respiratory rate) were used to create a regression model (PH-VS) that was internally validated and evaluated using area under the receiver operating curve (AUROC). Transfusion records were matched with blood bank records. Documentation of death and duration of intensive care were obtained from the trauma registry.

RESULTS

During the course of their hospital stay, 720 of the 17,988 patients in the study population died (4%), 2,266 (12.6%) required at least a 3-day stay in the intensive care unit (ICU), 1,171 (6.5%) required transfusions, and 210 (1.2%) received massive transfusions. The PH-VS model significantly outperformed any individual vital sign across all outcomes (average AUROC = 0.82), The PH-VS model correctly predicted that 512 of 777 (65.9%) and 580 of 931 (62.3%) patients in the study population would receive transfusions within the first 2 and 6 hours of admission, respectively.

CONCLUSIONS

The predictive ability of individual vital signs to predict outcomes is significantly enhanced with the model. This could support prehospital triage by enhancing decision makers' ability to match critically injured patients with appropriate resources with minimal delays.

Assessing trauma care provider judgement in the prediction of need for life-saving interventions

INTRODUCTION

Human judgement on the need for life-saving interventions (LSI) in trauma is poorly studied, especially during initial casualty management. We prospectively examined early clinical judgement and compared clinical experts' predictions of LSI to their later occurrence.

PATIENTS AND METHODS

Within 10-15 min of direct trauma admission, we surveyed the predictions of pre-hospital care providers (PHP, 92% paramedics), trauma centre nurses (RN), and attending or fellow trauma physicians (MD) on the need for LSI. The actual outcomes including fluid bolus, intubation, transfusion (<1h and 1-6h), and emergent surgical interventions were observed. Cohen's kappa statistic (K) and percentage agreement were used to measure agreement among provider responses. Sensitivity, specificity, negative predictive value (NPV) and positive predictive value (PPV) were calculated to compare clinical judgement to actual patient interventions.

RESULTS

Among 325 eligible trauma patient admissions, 209 clinical judgement of LSIs were obtained from all three providers. Cohen's kappa statistic for agreement between pairs of provider groups demonstrated no "disagreement" (K<0) between groups, "fair" agreement for fluid bolus (K=0.12-0.19) and blood transfusion 0-6h (K=0.22-0.39), and "moderate" (K=0.45-0.49) agreement between PHP and RN regarding intubation and surgical interventions, but no "excellent" (K ≥ 0.81) agreement between any pair of provider groups for any intervention. The percentage agreement across the different clinician groups ranged from 50% to 83%. NPV was 90-99% across providers for all interventions except fluid bolus.

CONCLUSIONS

Expert clinical judgement provides a benchmark for the prediction of major LSI use in unstable trauma patients. No excellent agreement exists across providers on LSI predictions. It is possible that quality improvement measures and computer modelling-based decision-support could reduce errors of LSI commission and omission found in resuscitation at major trauma centres and enhance decision-making in austere trauma settings by less well-trained providers than those surveyed.

Responsiveness to therapy for increased intracranial pressure in traumatic brain injury is associated with neurological outcome

In patients with severe traumatic brain injury, increased intracranial pressure (ICP) is associated with poor functional outcome or death. Hypertonic saline (HTS) is a hyperosmolar therapy commonly used to treat increased ICP; this study aimed to measure initial patient response to HTS and look for association with patient outcome. Patients >17 years old, admitted and requiring ICP monitoring between 2008 and 2010 at a large urban tertiary care facility were retrospectively enrolled. The first dose of hypertonic saline administered after admission for ICP >19mmHg was recorded and correlated with vital signs recorded at the bedside. The absolute and relative change in ICP at 1 and 2h after HTS administration was calculated. Patients were stratified by mortality and long-term (≥6 months) functional neurological outcome. We identified 46 patients who received at least 1 dose of HTS for ICP>19, of whom 80% were male, mean age 34.4, with a median post-resuscitation GCS score of 6. All patients showed a significant decrease in ICP 1h after HTS administration. Two hours post-administration, survivors showed a further decrease in ICP (43% reduction from baseline), while ICP began to rebound in non-survivors (17% reduction from baseline). When patients were stratified for long-term neurological outcome, results were similar, with a significant difference in groups by 2h after HTS administration. In patients treated with HTS for intracranial hypertension, those who survived or had good neurological outcome, when compared to those who died or had poor outcomes, showed a significantly larger sustained decrease in ICP 2h after administration. This suggests that even early in a patient's treatment, treatment responsiveness is associated with mortality or poor functional outcome. While this work is preliminary, it suggests that early failure to obtain a sustainable response to hyperosmolar therapy may warrant greater treatment intensity or therapy escalation.

Permutation entropy analysis of vital signs data for outcome prediction of patients with severe traumatic brain injury

Permutation entropy is computationally efficient, robust to outliers, and effective to measure complexity of time series. We used this technique to quantify the complexity of continuous vital signs recorded from patients with traumatic brain injury (TBI). Using permutation entropy calculated from early vital signs (initial 10-20% of patient hospital stay time), we built classifiers to predict in-hospital mortality and mobility, measured by 3-month Extended Glasgow Outcome Score (GOSE). Sixty patients with severe TBI produced a skewed dataset that we evaluated for accuracy, sensitivity and specificity. The overall prediction accuracy achieved 91.67% for mortality, and 76.67% for 3-month GOSE in testing datasets, using the leave-one-out cross validation. We also applied Receiver Operating Characteristic analysis to compare classifiers built from different learning methods. Those results support the applicability of permutation entropy in analyzing the dynamic behavior of TBI vital signs for early prediction of mortality and long-term patient outcomes.

Pharmacologic Treatment Reduces Pressure Times Time Dose and Relative Duration of Intracranial Hypertension

INTRODUCTION

Past work has shown the importance of the "pressure times time dose" (PTD) of intracranial hypertension (intracranial pressure [ICP] > 19 mm Hg) in predicting outcome after severe traumatic brain injury. We used automated data collection to measure the effect of common medications on the duration and dose of intracranial hypertension.

METHODS

Patients >17 years old, admitted and requiring ICP monitoring between 2008 and 2010 at a single, large urban tertiary care facility, were retrospectively enrolled. Timing and dose of ICP-directed therapy were recorded from paper and electronic medical records. The ICP data were collected automatically at 6-second intervals and averaged over 5 minutes. The percentage of time of intracranial hypertension (PTI) and PTD (mm Hg h) were calculated.

RESULTS

A total of 98 patients with 664 treatment instances were identified. Baseline PTD ranged from 27 (before administration of propofol and fentanyl) to 150 mm Hg h (before mannitol). A "small" dose of hypertonic saline (HTS; ≤250 mL 3%) reduced PTD by 38% in the first hour and 37% in the second hour and reduced the time with ICP >19 by 38% and 39% after 1 and 2 hours, respectively. A "large" dose of HTS reduced PTD by 40% in the first hour and 63% in the second (PTI reduction of 36% and 50%, respectively). An increased dose of propofol or fentanyl infusion failed to decrease PTD but reduced PTI between 14% (propofol alone) and 30% (combined increase in propofol and fentanyl, after 2 hours). Barbiturates failed to decrease PTD but decreased PTI by 30% up to 2 hours after administration. All reductions reported are significantly changed from baseline, P < .05.

CONCLUSION

Baseline PTD values before drug administration reflects varied patient criticality, with much higher values seen before the use of mannitol or barbiturates. Treatment with HTS reduced PTD and PTI burden significantly more than escalation of sedation or pain management, and this effect remained significant at 2 hours after administration.

Intracranial pressure response after pharmacologic treatment of intracranial hypertension

BACKGROUND

The accepted treatment of increased intracranial pressure (ICP) in patients experiencing severe traumatic brain injury is multimodal and algorithmic, obscuring individual effects of treatment. Using continuous vital signs monitoring, we sought to measure treatment effect and ascertain the accuracy of manual data recording.

METHODS

Patients older than 17 years, admitted and requiring ICP monitoring between 2008 and 2010 at a high-volume urban trauma center, were retrospectively evaluated. Timing and dose of ICP-directed therapy were recorded from paper and electronic medical records. ICP data were collected automatically at 6-second intervals and from manual charts. A statistical mixed model was applied to all data to account for multiple sampling.

RESULTS

A total of 117 patients met inclusion criteria; 450 treatments were administered when nursing records indicate an ICP greater than 20 mm Hg, while 968 treatments were given when ICP was greater than 20 mm Hg by automated data. Pharmacologic treatments identified include hypertonic saline (HTS), mannitol, barbiturates, and dose escalations of propofol or fentanyl infusions. Treatment with HTS resulted in the largest ICP decrease of the treatments examined, with a 1-hour ICP reduction of 8.8/9.9 mm Hg (for a small/large dose) according to manual data and a reduction of 3.0/2.4 mm Hg according to automated data. Propofol and fentanyl escalations resulted in smaller but significant ICP reductions. Mannitol (n = 8) resulted in statistically insignificant trends down in the first hour but rebounded by the second hour after administration. The average ICP in the hour before medication administration was higher for barbiturates (27 mm Hg) and mannitol (32 mm Hg) than for the other interventions (18-19 mm Hg).

CONCLUSION

ICP fell after administration of HTS, mannitol, or barbiturates and showed continued improvement after 2 hours. ICP fell initially after treatment with short-acting propofol and fentanyl but trended back up after 2 hours. Manually recorded data consistently overestimated treatment effectiveness. Automated data collection gives a more accurate assessment of patient status and responsiveness to treatment.

LEVEL OF EVIDENCE

Therapeutic study, level IV.

Timing of intracranial hypertension following severe traumatic brain injury

BACKGROUND

We asked whether continuous intracranial pressure (ICP) monitoring data could provide objective measures of the degree and timing of intracranial hypertension (ICH) in the first week of neurotrauma critical care and whether such data could be linked to outcome.

METHODS

We enrolled adult (>17 years old) patients admitted to our Level I trauma center within 6 h of severe TBI. ICP data were automatically captured and ICP 5-minute means were grouped into 12-hour time periods from admission (hour 0) to >7 days (hour 180). Means, maximum, percent time (% time), and pressure-times-time dose (PTD, mmHg h) of ICP >20 mmHg and >30 mmHg were calculated for each time period.

RESULTS

From 2008 to 2010, we enrolled 191 patients. Only 2.1% had no episodes of ICH. The timing of maximum PTD20 was relatively equally distributed across the 15 time periods. Median ICP, PTD20, %time20, and %time30 were all significantly higher in the 84-180 h time period than the 0-84 h time period. Stratified by functional outcome, those with poor functional outcome had significantly more ICH in hours 84-180. Multivariate analysis revealed that, after 84 h of monitoring, every 5% increase in PTD20 was independently associated with 21% higher odds of having a poor functional outcome (adjusted odds ratio = 1.21, 95% CI 1.02-1.42, p = 0.03).

CONCLUSIONS

Although early elevations in ICP occur, ICPs are the highest later in the hospital course than previously understood, and temporal patterns of ICP elevation are associated with functional outcome. Understanding this temporal nature of secondary insults has significant implications for management.

Study on characteristics of in vitro culture and intracellular transduction of exogenous proteins in fibroblast cell line of Liaoning cashmere goat

Establishment of fibroblast cell lines of endangered goat breeds and research on the gene or protein functions based on the cells made a significant contribution to the conservation and utilization of genetic resources. In this study, a fibroblast cell line of Liaoning cashmere goat, frozen in 174 cryovials with 5 × 10(6) cells each, was successfully established from 60 goats ear marginal tissues using explant culture and cryopreservation techniques. Biological analysis of in vitro cultured cell line showed that, the cells were morphologically consistent with fibroblasts; the average viability of the cells was 94.9 % before freezing and 90.1 % after thawing; the growth process of cells was consisted of a lag phase, a logarithmic phase and a plateau phase; cell population doubling time was 65.5 h; more than 90 % of cells were diploid prior to the 6th generation; Neither microbial contamination nor cross-contamination was detected. To determine cell permeability, intracellular path and stability of exogenous proteins during the transduction, a TAT protein transduction domain was fused to the C-terminus of enhanced green fluorescent protein, the established fibroblast cell line was treated with the purified exogenous proteins at various concentrations by adding them to the cell culture media for 1-24 h and assayed cell morphology and protein presence, it was found that the purified exogenous proteins readily entered cells at a concentration of 0.1 mg/ml within 1.5 h and some of them could translocate into nucleus, moreover, the exogenous proteins appeared to be stable inside cells for up to 24 h.

Statewide real-time in-flight trauma patient vital signs collection system

Continuous recorded in-flight vital signs monitoring and life-saving interventions linked to outcomes may provide better understanding of pre-hospital triage, care management and patient responses during the 'golden hour' of trauma care. Evaluation of 157 patients' vital signs data collected from our statewide network has identified episodes of physiological decompensation which holds promise for creation of new triage algorithms and enhanced trauma center preparedness.

Shortening time to stroke treatment using ambulance telemedicine: TeleBAT

OBJECTIVE

Patients with ischemic stroke treated with tissue plasminogen activator (rt-PA) have better outcomes when treated closer to the time of symptom onset and within the 3-hour window. We previously demonstrated the clinical use of TeleBAT, a mobile telemedicine system for stroke. We tested the impact of that system on time to treatment for patients with acute stroke.

METHODS

Validity and reliability were tested by comparing neurologic examination scores obtained using our wireless system, which transmits video of a patient from a moving ambulance to desktop computers, with those obtained using the National Institute of Neurological Disorders and Stroke training videotape. TeleBAT validity and good interrater reliability were defined a priori as a kappa statistic of r > 0.5. We compared the average time to treatment for our TeleBAT-evaluated intervention group with that for our control group. The intervention group consisted of two actor patients with stroke mimicking 12 stroke scenarios and evaluated using TeleBAT. The control group consisted of patients with stroke evaluated and treated with rt-PA on arrival to the emergency department. Data were analyzed using standard t test.

RESULTS

National Institutes of Health Stroke Scale items calculated by the neurologists suggest TeleBAT is valid for assessing patients with stroke remotely. Interrater reliability was high: the neurologists gleaned the same information from TeleBAT transmissions. Kappa values for both validity and reliability exceeded 0.5. The mean time to treatment for patients assessed by TeleBAT was 17 +/- 4 minutes compared with 33 +/- 17 minutes for our control group (P = .0033).

CONCLUSION

TeleBAT seems to be a valid and reliable means of evaluating stroke neurologic deficits. Time to treatment was shortened using ambulance transport time to evaluate patients as candidates for thrombolytic therapy. Future studies should use a randomized design with patients with acute stroke.

Stability of thermally hypersensitised phosphosilicate waveguides and the characteristic growth curve

Low temperature (80 0 C) hypersensitised hydrogen-loaded phosphosilicate optical fibre is found to be unstable, decaying progressively at room temperature. However, the hypersensitisation process linearises the grating growth characteristic curve. Further, a negative index contribution is inferred at low fluence in the presence of hydrogen.

Low-temperature hypersensitization of phosphosilicate waveguides in hydrogen

Conventional hydrogen loading of phosphosilicate optical fibers at relatively low temperatures (80 degrees C) is sufficient to enhance the fiber's photosensitivity after hydrogen outdiffusion, allowing permanent Bragg grating structures to be produced. Thermal sensitization is proposed to be a major contributor to stable index change.

Ultraviolet-induced absorption losses in hydrogen-loaded optical fibers and in presensitized optical fibers

Reduced hydroxyl formation in presensitized fibers exposed to cw 244-nm light after hydrogen outdiffusion is reported. The OH band in the presensitized fiber shifts toward 1390 nm. In the fully hydrogen-loaded fiber the OH band is centered at 1397 nm and does not shift with fluence.

Natural killer cell immunodeficiency in HIV disease is manifest by profoundly decreased numbers of CD16+CD56+ cells and expansion of a population of CD16dimCD56- cells with low lytic activity

Natural killer (NK) cells were enumerated by three-color immunofluorescence in 255 uninfected and 399 human immunodeficiency virus-infected adults. Several dramatic alterations were observed. First, the median number and percentage of CD16+CD56+ NK cells, the subset that comprises > 90% of the NK cells in healthy adults, were severely decreased (median, 175/mm3 in uninfected controls; 63/mm3 in HIV-infected non-AIDS subjects). Even subjects with > 800 CD4+ cells/mm3 had decreased CD16+CD56+ NK cell levels (97/mm3). Second, the number of CD16+CD56- cells, an NK population that is rare in healthy adults, was elevated (median, 20/mm3 in uninfected controls; 64/mm3 in HIV-seropositive non-AIDS subjects). Third, the expression of CD16 on the NK cells was markedly reduced; some CD56+ cells and virtually all CD56- cells were CD16dim. Fourth, fluorescence-activated cell-sorting studies revealed little NK- or antibody-dependent cellular cytotoxic activity in the CD16dimCD56- cell population. These results indicate that the pathogenesis of HIV disease includes numerical alterations in subpopulations of NK cells. A better understanding of how HIV infection causes this aspect of pathogenesis is needed.

An audio-video system for automated data acquisition in the clinical environment. LOTAS Group

OBJECTIVE

Our objective was to develop an audiovideo data acquisition system that facilitates studying the activities of anesthesia care providers in the clinical environment.

METHOD

Ceiling-mounted miniature video cameras, vital sign monitors, and videocassette recorders (VCRs) were interfaced to digital computers in two patient admitting areas and two operating rooms of a trauma center. This video data acquisition system network (VASNET) is simple to operate. Insertion of a videotape activates the system and begins video overlay of updated vital signs onto the video image every 5 sec. Recorded data is passed via a local area network, allowing remote monitoring of the data acquisition process. To facilitate analysis of the video at a later time, the image, soundtrack, and vital signs data are stamped with the same time code. Each tape is initialized by recording the data file name and wall clock time for 30 sec at the start of taping. This initialization enables comparison of the video recordings with anesthesia, surgical, and nursing records.

RESULTS

During 2 years of operation, VASNET was used to record over 100 cases of acute trauma management. Vital signs overlaid onto the video image identified when patient monitors were in use and providing data. Participants found videotape review useful in assessing their own performance. VASNET was nonintrusive and acquired data with minimum user interaction. In one operating room, separate from the trauma center, VASNET was installed to function as a remote monitor, with the option of videotaping. Although users were aware of when videotaping occurred, once patient management was underway, the activities of the anesthesia care providers did not appear to be influenced by the videocassette recording. Equipment maintenance was not excessive. The most frequent problems were changes to the VCR control settings and disconnection of the power supply or interface connections.

CONCLUSIONS

Videotapes of the process of anesthetizing and resuscitating trauma patients provided a record of the activities of anesthesia care providers. Video vignettes may be useful training tools. Excerpts from real scenarios can be incorporated into anesthesia stimulators. The soundtrack and timing of real events from such video acquisition may be useful in the development of multimedia simulations of trauma patient resuscitation. The data collection may be useful for research into human performance, ergonomics, training techniques, quality assurance, and certification of anesthesia care providers in trauma patient management. Potential additional applications of VASNET include remote monitoring of patients in the operating room, in the intensive care unit, during transportation, in hazardous environments, and in the field. Such VASNET telemetry may facilitate the availability of expert opinions during medical and other consultations.

Two Isomeric α and β Aspartyl Dodecapeptides and Their Cyclic Amino Succinyl Analogue From the Australian Green Tree Frog Litoria gilleni

Three related peptides, caeridins 1.1-1.3, have been isolated from the green tree frog Litoria gilleni. Caeridins 1.1 and 1.2 are dodecapeptides differing only in having α and β Asp at residue 4 [viz. Gly Leu Leu Asp Gly Leu Leu Gly Thr Leu Gly Leu (NH2)]. Caeridin 1.3 is the corresponding cyclic amino succinyl derivative derived formally by cyclization of Asp(4) and Gly (5). Hydrolysis of caeridin 1.3 yields caeridin 1.1 and 1.2 in the ratio 3:1. This constitutes a rare case of the isolation of three such related peptides from a natural system.