Distributed Maritime Operations and the Medical Challenge: How a Medical Common Operating Picture Can Help Bridge the Gap.

This work explores the challenges of delivering medical care in the geographically dispersed and resource-constrained environment of Distributed Maritime Operations (DMO) and Expeditionary Advanced Base Operations (EABO). Traditional medical planning approaches may struggle to adapt to the vast operational space, extended evacuation times, and limited medical force present in these scenarios. The concept of a Medical Common Operating Picture (COP) emerges as a potential solution. By providing a shared view of the medical situation across the theater, encompassing logistics, personnel, and patient data, a medical COP has the potential to facilitate medical command and control (MED C2) in DMO/EABO. The implementation of a medical COP has the potential to optimize resource allocation, enhance situational awareness, streamline medical evacuation, and reduce healthcare provider moral injury in large-scale combat operations. A medical COP will allow medical planners to make informed decisions on triage, resupply, and evacuation, ensuring the best use of limited medical resources. This is done by leveraging a comprehensive understanding of the medical landscape, enabling informed clinical and operational decision-making by humanitarian and combat personnel respectively. A fully realized medical COP system will enable a dynamic theater evacuation policy, balancing the conflicting needs of patient care at higher echelons with the operational expediency of returning servicemembers to their operational units, thereby maximizing evacuation effectiveness. It will further enable medical personnel to perform dynamic casualty triage based on operational realities, mitigating potential ethical dilemmas. Implementing such a medical COP system will require overcoming communication limitations to facilitate data exchange and potentially integrating clinical decision support tools for real-time data analysis and recommendations. It will also require the rapid adoption of modernized operational medicine documentation solutions by medical assets within the operational forces. Ultimately, this work suggests that a medical COP has the potential to bridge the gap between traditional medical planning and the unique demands of DMO/EABO, ultimately optimizing casualty care, maximizing resource efficiency, and preserving the fighting force.

Regional anesthesia in resource-limited and disaster environments: a daring discourse.

Regional anesthesia (RA) is commonly used in perioperative settings of developed and well-resourced environments. RA has significant potential benefits when used in resource-limited environments, including disaster, mass casualty, and wartime environments. RA offers benefits over general anesthesia and opioid-based analgesia, including decreased risk of complications, decreased reliance on mechanical ventilation, improved cost efficiency, and others. The decreasing cost of ultrasound matched with its smaller size and portability increases the availability of ultrasound in these environments, making ultrasound-guided RA more feasible. This daring discourse discusses some historical examples of RA in ultralow resource environments, both man-made disasters and natural disasters. Future investigations should increase the usefulness and availability of RA in resource-limited environments.

Surgical Casualty Care in Contested Distributed Maritime Operations: Lessons Learned From the Falklands War.

The Falklands Campaign was fought a significant distance from the home base of the British Fleet. The planning and delivery of medical care during this campaign can provide significant lessons for strategic medical planning in other far spread geographic locations, including the Indo-Pacific region. Consideration of doctrine, including Role 1-4 facilities and the golden hour, may need to be reconsidered in light of changing scenarios. New concepts such as the "90-in-90" and "3-in-3" are also discussed as a framework for future planning in the U.S. Indo-Pacific Command area of responsibility.

The Association Between Borderline Dysnatremia and Perioperative Morbidity and Mortality: Retrospective Cohort Study of the American College of Surgeons National Surgical Quality Improvement Program Database.

BACKGROUND: Hyponatremia and hypernatremia, as conventionally defined (<135 mEq/L and >145 mEq/L, respectively), are associated with increased perioperative morbidity and mortality. However, the effects of subtle deviations in serum sodium concentration within the normal range are not well-characterized. OBJECTIVE: The purpose of this analysis is to determine the association between borderline hyponatremia (135-137 mEq/L) and hypernatremia (143-145 mEq/L) on perioperative morbidity and mortality. METHODS: A retrospective cohort study was performed using data from the American College of Surgeons National Surgical Quality Improvement Program database. This database is a repository of surgical outcome data collected from over 600 hospitals across the United States. The National Surgical Quality Improvement Program database was queried to extract all patients undergoing elective, noncardiac surgery from 2015 to 2019. The primary predictor variable was preoperative serum sodium concentration, measured less than 5 days before the index surgery. The 2 primary outcomes were the odds of morbidity and mortality occurring within 30 days of surgery. The risk of both outcomes in relation to preoperative serum sodium concentration was modeled using weighted generalized additive models to minimize the effect of selection bias while controlling for covariates. RESULTS: In the overall cohort, 1,003,956 of 4,551,726 available patients had a serum sodium concentration drawn within 5 days of their index surgery. The odds of morbidity and mortality across sodium levels of 130-150 mEq/L relative to a sodium level of 140 mEq/L followed a nonnormally distributed U-shaped curve. The mean serum sodium concentration in the study population was 139 mEq/L. All continuous covariates were significantly associated with both morbidity and mortality (P<.001). Preoperative serum sodium concentrations of less than 139 mEq/L and those greater than 144 mEq/L were independently associated with increased morbidity probabilities. Serum sodium concentrations of less than 138 mEq/L and those greater than 142 mEq/L were associated with increased mortality probabilities. Hypernatremia was associated with higher odds of both morbidity and mortality than corresponding degrees of hyponatremia. CONCLUSIONS: Among patients undergoing elective, noncardiac surgery, this retrospective analysis found that preoperative serum sodium levels less than 138 mEq/L and those greater than 142 mEq/L are associated with increased morbidity and mortality, even within currently accepted "normal" ranges. The retrospective nature of this investigation limits the ability to make causal determinations for these findings. Given the U-shaped distribution of risk, past investigations that assume a linear relationship between serum sodium concentration and surgical outcomes may need to be revisited. Likewise, these results question the current definition of perioperative eunatremia, which may require future prospective investigations.

Machine Learning to Predict Discharge Destination After Total Knee Arthroplasty and Total Hip Arthroplasty.

Discharge destination impacts costs and perioperative planning for primary total knee (TKA) or hip arthroplasty (THA). The purpose of this study was to create a tool to predict discharge destination in contemporary patients. Models were developed using more than 400,000 patients from the National Surgical Quality Improvement Program database. Models were compared with a previously published model using area under the receiver operating characteristic curve (AUC) and decision curve analysis (DCA). AUC on patients with TKA was 0.729 (95% confidence interval [CI]: 0.719 to 0.738) and 0.688 (95% CI: 0.678 to 0.697) using the new and previous models, respectively. AUC on patients with THA was 0.768 (95% CI: 0.758 to 0.778) and 0.726 (95% CI: 0.714 to 0.737) using the new and previous models, respectively. DCA showed substantially improved net clinical benefit. The new models were integrated into a web-based application. This tool enhances clinical decision making for predicting discharge destination following primary TKA and THA. (Journal of Surgical Orthopaedic Advances 32(4):252-258, 2023).

Use of a head-mounted patient display in a task driven anaesthesia simulator: a randomised trial.

INTRODUCTION: Head-mounted displays (HMDs) are becoming increasingly investigated in the realm of healthcare. These devices are worn on the user's head and display information directly to the eye. This allows for near-constant delivery of information, regardless of user position. Increasing advances in technology have allowed for miniaturisation, increasing sophistication, wireless capability and prolonged battery life, all of which allow for more opportunities for these devices to be used in a clinical setting. METHODS: A prospective, randomised, controlled, parallel-group study was conducted. Subjects were randomised to either an HMD group or a non-HMD group. All subjects then underwent a standardised intraoperative care simulation experience consisting of multiple procedures that required completion within a set time limit. During this period, subjects concurrently monitored the physiological state of a simulated patient. Multiple standardised physiological derangements were displayed to the subjects via either the worn HMD or standard monitors. The primary outcome was the time to recognition of these physiological derangements. RESULTS: A total of 39 anaesthesia providers were enrolled in this study. There was a significant decrease in the total time it took them to recognise the simulated physiological derangements in the HMD group (difference of 38.2% (95% CI 20.3% to 56.1%); p=0.011) No significant differences in the time that it took to perform the required simulated procedures were observed. Significantly fewer physiological derangements were overlooked by the HMD group than the control group overall (relative risk reduction 0.78 (95% CI 0.31 to 0.94); p=0.003). CONCLUSIONS: Recent advances in HMD technology may be able to produce a functional adjunctive monitoring device that improves the speed with which anaesthesia providers respond to intraoperative events. This benefit comes without increasing distraction from the task. Further studies in true operative environments are needed to validate this technology.

Pulse Arrival Time Is Associated With Hemorrhagic Volume in a Porcine Model: A Pilot Study.

BACKGROUND: Hemorrhage is a major cause of preventable death worldwide, and early identification can be lifesaving. Pulse wave contour analysis has previously been used to infer hemodynamic variables in a variety of settings. We hypothesized that pulse arrival time (PAT), a form of pulse wave contour analysis which is assessed via electrocardiography (ECG) and photoplethysmography (PPG), is associated with hemorrhage volume. METHODS: Yorkshire-Cross swine were randomized to hemorrhage (30 mL/kg over 20 minutes) vs. control. Continuous ECG and PPG waveforms were recorded with a novel monitoring device, and algorithms were developed to calculate PAT and PAT variability throughout the respiratory cycle, termed "PAT index" or "PAT_I." Mixed effects models were used to determine associations between blood loss and PAT and between blood loss and PAT_I to account for clustering within subjects and investigate inter-subject variability in these relationships. RESULTS: PAT and PAT_I data were determined for ∼150 distinct intervals from five subjects. PAT and PAT_I were strongly associated with blood loss. Mixed effects modeling with PAT alone was substantially better than PAT_I alone (R2 0.93 vs. 0.57 and Akaike information criterion (AIC) 421.1 vs. 475.5, respectively). Modeling blood loss with PAT and PAT_I together resulted in slightly improved fit compared to PAT alone (R2 0.96, AIC 419.1). Mixed effects models demonstrated significant inter-subject variability in the relationships between blood loss and PAT. CONCLUSIONS: Findings from this pilot study suggest that PAT and PAT_I may be used to detect blood loss. Because of the simple design of a single-lead ECG and PPG, the technology could be packaged into a very small form factor device for use in austere or resource-constrained environments. Significant inter-subject variability in the relationship between blood loss and PAT highlights the importance of individualized hemodynamic monitoring.

Refining the rat sciatic nerve block: a novel ultrasound-guided technique.

Murine translational models are an important tool to understand pain pathophysiology. One procedure used frequently in murine research is the sciatic nerve block. This study sought to demonstrate the use of ultrasound-guided sciatic nerve block in a cadaveric murine model. A total of 40 injections were performed in 20 Sprague-Dawley male 18-month-old rat cadavers. Necropsy was performed to identify staining of the sciatic nerve. Staining with methylene blue occurred in 40 of 40 ultrasound-guided injections. The extremely accurate nature of this block under ultrasound guidance is favorable for future translational studies in rats undergoing sciatic nerve blocks. This method may represent a significant improvement in current methods.

Impact of a Multidisciplinary Long-Term Opioid Therapy Safety Program at a Military Tertiary Academic Medical Center.

OBJECTIVE: In light of the ongoing opioid crisis, Naval Medical Center Portsmouth (NMCP) created the Long-Term Opioid Therapy Safety (LOTS) program to reduce risks and improve long-term opioid therapy outcomes. Our primary outcome was change in compliance with the recommended safety metrics. DESIGN: This is a retrospective cohort study performed at NMCP, a large military academic medical center providing comprehensive medical care to DoD beneficiaries. The NMCP LOTS program provides both patient and provider narcotic education as well as medical record auditing. The NMCP LOTS program promotes adherence to published CDC, the DVA, and DoD guidelines. METHODS: Anonymized data were compiled each fiscal quarter and were analyzed retrospectively. Adult patients prescribed opioids for at least 90 days without a gap of 30 days between prescriptions were included in this study. The investigators recorded and reported provider compliance with LOTS metrics over the same period. RESULTS: Compliance with the recommended safety metrics improved. We noted a decrease in the number of long-term opioid patients, concurrent benzodiazepine prescriptions, and patients prescribed greater than 90 morphine equivalents per day during the observation period. The number of naloxone prescriptions for LOTS patients also increased, reflecting improved guideline adherence. CONCLUSION: Systematic education and feedback to providers are effective in creating a system and culture of opioid reduction, safe opioid prescribing, and system accountability. This article presents a comprehensive approach to modifying prescribing patterns of long-term opioids in a large healthcare system.

Hemodynamic Effects of Cardiovascular Medications in a Normovolemic and Hemorrhaged Yorkshire-cross Swine Model.

The Yorkshire-cross swine model is a valuable translational model commonly used to study cardiovascular physiology and response to insult. Although the effects of vasoactive medications have been well described in healthy swine, the effects of these medications during hemorrhagic shock are less studied. In this study, we sought to expand the utility of the swine model by characterizing the hemodynamic changes that occurred after the administration of commonly available vasoactive medications during euvolemic and hypovolemic states. To this end, we anesthetized and established femoral arterial, central venous, and pulmonary arterial access in 15 juvenile Yorkshire-cross pigs. The pigs then received a series of rapidly metabolized but highly vasoactive medications in a standard dosing sequence. After completion of this sequence, each pig underwent a 30-mL/kg hemorrhage over 10 min, and the standard dosing sequence was repeated. We then used standard sta- tistical techniques to compare the effects of these vasoactive medications on a variety of hemodynamic parameters between the euvolemic and hemorrhagic states. All subjects completed the study protocol. The responses in the hemorrhagic state were often attenuated or even opposite of those in the euvolemic state. For example, phenylephrine decreased the mean arterial blood pressure during the euvolemic state but increased it in the hemorrhagic state. These results clarify previously poorly defined responses to commonly used vasoactive agents during the hemorrhagic state in swine. Our findings also demonstrate the need to consider the complex and dynamic physiologic state of hemorrhage when anticipating the effects of vasoactive drugs and planning study protocols.

Regional Anesthesia for Symptomatic Treatment of Stingray Envenomation.

Stingray envenomation is common in coastal regions around the world and may result in intense pain that can be challenging to manage. Described therapies involve hot water immersion and potentially other options such as opioid and nonopioid analgesics, removal of the foreign body, wound debridement, antibiotics for secondary infection, and tetanus toxoid. However, for some patients, this may not be enough. Peripheral nerve blockade is a frequently used perioperative analgesic technique, but it has rarely been described in the management of stingray envenomation. Here, we report a case of stingray envenomation in an otherwise healthy 36-y-old male with pain refractory to traditional therapies. After admission for pain control, the patient received an ultrasound-guided sciatic popliteal nerve block. Upon completion of the peripheral nerve block, the patient reported rapid and complete resolution of the intense pain, which did not return thereafter.

Machine Learning to Predict Fascial Dehiscence after Exploratory Laparotomy Surgery.

BACKGROUND: Fascial dehiscence following exploratory laparotomy is associated with significant morbidity and increased mortality. Previously published risk prediction models for fascial dehiscence are dated and limit a surgeon's ability to perform reliable risk assessment intraoperatively. We sought to determine if machine learning can predict fascial dehiscence after exploratory laparotomy. MATERIALS AND METHODS: A retrospective cohort study was conducted of 93,024 patients undergoing exploratory laparotomy from the 2011-2018 ACS NSQIP data files. Data were divided into training (2011-2016, n = 69,969) and temporal validation (2017-2018, n = 23,055) cohorts. A clinical decision support tool was developed using the model generated via machine learning techniques. RESULTS: 1,332 (1.9%) patients in the training cohort and 390 (1.7%) patients in the temporal validation cohort developed fascial dehiscence. The area under the receiver operating characteristic curve was 0.69 (95% CI 0.66 to 0.72) in the validation cohort. Model predictions demonstrated excellent probability calibration. Decision curve analysis calculates net clinical benefit within a threshold range of 0.8%-4.5%. Operative time, surgical site and deep space infections, and body mass index were among the most important features for model predictions. Finally, operative time, sodium level, and hematocrit demonstrated non-linear relationships with predicted risk. CONCLUSION: A clinical decision support tool for predicting fascial dehiscence after exploratory laparotomy was created and validated on a contemporary, national patient cohort using machine learning. The tool calculates net clinical benefit and can be used at the point of care. Some identified risk factor relationships were found to be complex and non-linear, highlighting the ability of some machine learning applications to capture nuanced, patient-specific risk profiles.

Ultrasound Versus Fluoroscopy for Stellate Ganglion Block: A Cadaveric Study.

OBJECTIVE: Post-Traumatic Stress Disorder (PTSD) is a common psychiatric disorder. Recent investigations have demonstrated effectiveness of Stellate Ganglion Blocks (SGB) for reducing symptoms associated with PTSD. Both fluoroscopic guided and ultrasound guided SGB have been described and are regularly used in clinical practice. This study sought to evaluate differences in block performance when comparing fluoroscopic versus ultrasound guided SGB. DESIGN: Cadaveric Pilot Study. SETTING: Academic Research Laboratory. SUBJECTS: Ten Soft-Cured Human Cadavers. METHODS: Ten soft-cured human cadavers were used after being at room temperature for 3 hours. Fluoroscopic and ultrasound guided injections were both performed on each cadaver, randomized to left or right sidedness. In total, 7 mL of omnipaque and methylene blue (5:1) was injected in each side. Injectate spread was assessed by measuring vertebral body spread under fluoroscopy. Successful staining of the sympathetic trunk was assessed under cadaveric dissection, with visualization of the sympathetic trunk stained with methylene blue. RESULTS: Ultrasound guided injections resulted in successful staining in 9 of 10 injections, while 6 of 10 for fluoroscopic guidance (P = .3034). The average spread in the ultrasound group was 4.0 compared with 5.2 for the fluoroscopic group (P =.088). In the four fluoroscopic guided injections which failed to stain, the injection occurred posterior to the prevertebral fascia. In the single ultrasound guided block that failed to stain, the injection was in the carotid sheath. CONCLUSIONS: While there appeared to be a trend favoring ultrasound guidance, no statistical significance was achieved. This was likely due to this being a limited pilot study. Numerous limitations exist in cadaveric studies, and future investigations should be completed to further study this comparison. That said, the use of the SGB may provide significant relief for patients suffering with PTSD.

The effect of longer-range waviness on X-ray reflectivity measurements.

A model for calculating the X-ray reflectivity (XRR) of surfaces to extract both roughness and waviness features is presented. Expressions of reflectivity intensity are derived as a function of root-mean-square (RMS) roughness σ, RMS waviness σL, and the cut-off frequency between the features ω0. Experiments were conducted at the Advanced Light Source at Lawrence Berkeley National Laboratory, beamline 8.3.2, on BK7 glass manufactured with a multi-step polishing process to validate the model, and were compared with atomic force microscopy (AFM), Fizeau interferometry and surface profilometry measurements. The parameter results and their deviations for XRR measurements were σ = 2.9 ± 0.2 nm and σL = 14.6 ± 0.5 nm with a wavelength cut-off of 1/(18 ±â€…2) µm-1, while the results from the AFM, Fizeau and profilometry measurements were σAFM = 3.4 ± 0.4 nm, σL,Fizeau = 21.6 nm, σprof = 4.0 ± 0.1 nm, and σL,prof = 21.4 ± 0.1 nm with cut-offs for the profilometry and Fizeau measurements limited to frequencies of (1/16) µm-1 to (1/4) mm-1.

Predicting Treatment Success with Facet Syndrome: An Algorithm to Predict Lumbar Radiofrequency Ablation Responders in a Military Population.

OBJECTIVE: Radiofrequency ablation (RFA) of the medial branch nerve is a commonly performed procedure for patients with facet syndrome. RFA has previously been demonstrated to provide long-term functional improvement in approximately 50% of patients, including those who had significant pain relief after diagnostic medial branch block. We sought to identify factors associated with success of RFA for facet pain. DESIGN: Active-duty military patients who underwent lumbar RFA (L3, L4, and L5 levels) over a 3-year period were analyzed. Defense and Veterans Pain Rating Scale (DVPRS) and Oswestry Disability Index (ODI) scores were assessed the day of procedure and at the 2-month and 6-month follow-up. These data were analyzed to identify associations between patient demographics, pain, and functional status and patients' improvement after RFA, with a primary outcome of ODI improvement and a secondary outcome of pain reduction. RESULTS: Higher levels of starting functional impairment (starting ODI scores of 42.9 vs. 37.5; P = 0.0304) were associated with a greater likelihood of improvement in functional status 6 months after RFA, and higher starting pain scores (DVPRS pain scores of 6.1 vs. 5.1; P < 0.0001) were associated with a higher likelihood that pain scores would improve 6 months after RFA. A multivariate logistic regression was then used to develop a scoring system to predict improvement after RFA. The scoring system generated a C-statistic of 0.764, with starting ODI, pain scores, and both gender and smoking history as independent variables. CONCLUSIONS: This algorithm compares favorably to that of diagnostic medial branch block in terms of prediction accuracy (C-statistic of 0.764 vs. 0.57), suggesting that its use may improve patient selection in patients who undergo RFA for facet syndrome.

A Novel Low-Cost Ventilator for Use in a Worldwide Pandemic: The Portsmouth Ventilator.

The ongoing severe acute respiratory syndrome coronavirus 2 or coronavirus disease 2019 pandemic has demonstrated the potential need for a low-cost, rapidly deployable ventilator. Based on this premise, we sought to design a ventilator with the following criteria: 1) standard components that are accessible to the public, 2) "open-source" compatibility to allow anyone to easily recreate the system, 3) ability to ventilate in acute respiratory distress syndrome, and 4) lowest possible cost to provide adequate oxygenation and ventilation. DESIGN: We pursued development of a pneumatic-type ventilator. The basic design involves three electrically controlled solenoid valves, a pressure chamber, the patient breathing circuit, a positive end-expiratory pressure valve, and an electronics control system. Multiple safety elements were built into the design. The user-friendly interface allows simple control of ventilator settings. The ventilator delivers a hybrid form of pneumatic, assist-control ventilation, with predicted tidal volumes of 300-800 mL, positive end-expiratory pressure 0-20 cm H2O, and Fio2 21-100%. MAIN RESULTS: The ventilator was extensively tested with two separate high-fidelity lung simulators and a porcine in vivo model. Both lung simulators were able to simulate a variety of pathologic states, including obstructive lung disease and acute respiratory distress syndrome. The ventilator performed well across all simulated scenarios. Similarly, a porcine in vivo model was used to assess performance in live tissue, with a specific emphasis on gas exchange. The ventilator performed well in vivo and demonstrated noninferior ventilation and oxygenation when compared with the standard ventilator. CONCLUSIONS: The Portsmouth Ventilator was able to perform well across all simulated pathologies and in vivo. All components may be acquired by the public for a cost of approximately $250 U.S.D. Although this ventilator has limited functionality compared with modern ventilators, the simple design appears to be safe and would allow for rapid mass production if ventilator surge demand exceeded supply.

Bolus epidural infusion improves spread compared with continuous infusion in a cadaveric porcine spine model.

BACKGROUND: The administration of epidural anesthesia during labor is a common technique used to reduce the pain of childbirth. We sought to compare standard infusion strategies of continuous epidural infusions (CEI) with programmed intermittent epidural bolus (PIEB) to assess the length of spread in terms of vertebral body length. Based on previous clinical data in humans, the PIEB was associated with improved pain control and decreased total dose of local anesthetic. We hypothesized that the PIEB was associated with increased spread when compared with CEI. METHODS: Thirty female Yorkshire-cross swine cadavers were used to compare three infusion strategies, continuous infusion (CEI) 10 mL/hour programmed continuously, multiple bolus (MB) 2 mL given every 12 min for 10 mL total and 10 mL delivered in a single bolus (SB). Radiographs were used to identify the spread of the radiopaque contrast dye, and a number of vertebral bodies covered were measured to assess spread. RESULTS: Overall, the CEI had an average spread of 5.6 levels, MB 7.9 and SB 10.4. The differences between SB and MB (p=0.011), SB and CEI (p<0.001) and MB and CEI (p=0.028) were all found to be significant. CONCLUSIONS: We demonstrated increased spread of epidural contrast with programmed intermittent bolus strategies. This supports previous evidence of improved patient outcomes with PIEB strategy compared with CEI, and encourages the use of PIEB in the appropriate patient population.