Time-Controlled Adaptive Ventilation (TCAV): a personalized strategy for lung protection.

Acute respiratory distress syndrome (ARDS) alters the dynamics of lung inflation during mechanical ventilation. Repetitive alveolar collapse and expansion (RACE) predisposes the lung to ventilator-induced lung injury (VILI). Two broad approaches are currently used to minimize VILI: (1) low tidal volume (LVT) with low-moderate positive end-expiratory pressure (PEEP); and (2) open lung approach (OLA). The LVT approach attempts to protect already open lung tissue from overdistension, while simultaneously resting collapsed tissue by excluding it from the cycle of mechanical ventilation. By contrast, the OLA attempts to reinflate potentially recruitable lung, usually over a period of seconds to minutes using higher PEEP used to prevent progressive loss of end-expiratory lung volume (EELV) and RACE. However, even with these protective strategies, clinical studies have shown that ARDS-related mortality remains unacceptably high with a scarcity of effective interventions over the last two decades. One of the main limitations these varied interventions demonstrate to benefit is the observed clinical and pathologic heterogeneity in ARDS. We have developed an alternative ventilation strategy known as the Time Controlled Adaptive Ventilation (TCAV) method of applying the Airway Pressure Release Ventilation (APRV) mode, which takes advantage of the heterogeneous time- and pressure-dependent collapse and reopening of lung units. The TCAV method is a closed-loop system where the expiratory duration personalizes VT and EELV. Personalization of TCAV is informed and tuned with changes in respiratory system compliance (CRS) measured by the slope of the expiratory flow curve during passive exhalation. Two potentially beneficial features of TCAV are: (i) the expiratory duration is personalized to a given patient's lung physiology, which promotes alveolar stabilization by halting the progressive collapse of alveoli, thereby minimizing the time for the reopened lung to collapse again in the next expiration, and (ii) an extended inspiratory phase at a fixed inflation pressure after alveolar stabilization gradually reopens a small amount of tissue with each breath. Subsequently, densely collapsed regions are slowly ratcheted open over a period of hours, or even days. Thus, TCAV has the potential to minimize VILI, reducing ARDS-related morbidity and mortality.

Brief Report: Diabetic Keto-Acidosis (DKA) Induced Hypothermia may be Neuroprotective in Cardiac Arrest.

Despite the decreased survival associated with diabetes with out-of-hospital cardiac arrest and the overall low survival to hospital discharge, we would like to present two cases of OHCA in diabetics who despite prolonged resuscitation efforts had complete neurological recovery likely due to concomitant hypothermia. There is a steady decreasing rate of ROSC with longer durations of CPR so that outcomes are best when <20 minutes compared to prolonged resuscitation efforts (>30-40 minutes). It has been previously recognized that hypothermia prior to cardiac arrest can be neurologically protective even with up to 9 hours of cardiopulmonary resuscitation. Hypothermia has been associated with DKA and although often indicates sepsis with mortality rates of 30-60%, it may indeed be protective if occurring prior to cardiac arrest. The critical factor for neuroprotection may be a slow drop to a temperature <250C prior to OHCA as is achieved in deep hypothermic circulatory arrest for operative procedures of the aortic arch and great vessels. It may be worthwhile continuing aggressive resuscitation efforts even for prolonged periods before attaining ROSC for OHCA in patients found hypothermic from metabolic illnesses as compared to only from environmental exposures (avalanche victims, cold water submersions, etc.) as has been traditionally reported in the medical literature.

Gestalt clinical severity score (GCSS) as a predictor of patient severity of illness or injury.

OBJECTIVE: To determine if clinical judgement is accurate to predict the severity of injury or illness, and can be used at patient arrival when other formal scoring systems are not yet available. DESIGN: A multicenter pilot study using a prospective observational convenience sample of patients arriving by EMS to the emergency department (ED) or Trauma Center. SETTING: Two urban, Level 1 trauma centers at academic tertiary care hospitals. PATIENTS: Medical and trauma patients age 18 and older transported by EMS (N = 216). Exclusion criteria (prior to arrival): intubation, assisted ventilation (BVM or NPPV), CPR in progress, prisoners, or previously present motor or speech deficits. MEASUREMENTS: Completion of a novel 15-point scale of Verbal, Motor, and Facial Expression within 1-2 min of arrival by a clinician outside of the treatment team. Primary endpoint was the immediate disposition from the ED or Trauma Center: Home, Brief Observation (<24 h), Admission to Floor, ICU (OR and IR as surrogates since these patients ultimately go to the ICU), or Morgue. RESULTS: Univariate analysis revealed a strong, positive monotonic correlation between GCSS and disposition (Rho = 0.693, p < .0001). Multivariable logistic regression revealed the "best" model included GCSS and age (group 18-44 years old versus all the other age groups) (p < .0001). There was a 156% increase in the odds of being discharged home (versus being admitted) for a one-unit increase in GCSS (OR = 2.56, 95% CI 1.94, 3.37). CONCLUSIONS: Physicians can make accurate predictions of severity of injury and illness using a gestalt method and the scoring system we have developed as patient disposition correlates well with GCSS score. GCSS is most accurate with the 18-44 age group.

Myths and Misconceptions of Airway Pressure Release Ventilation: Getting Past the Noise and on to the Signal.

In the pursuit of science, competitive ideas and debate are necessary means to attain knowledge and expose our ignorance. To quote Murray Gell-Mann (1969 Nobel Prize laureate in Physics): "Scientific orthodoxy kills truth". In mechanical ventilation, the goal is to provide the best approach to support patients with respiratory failure until the underlying disease resolves, while minimizing iatrogenic damage. This compromise characterizes the philosophy behind the concept of "lung protective" ventilation. Unfortunately, inadequacies of the current conceptual model-that focuses exclusively on a nominal value of low tidal volume and promotes shrinking of the "baby lung" - is reflected in the high mortality rate of patients with moderate and severe acute respiratory distress syndrome. These data call for exploration and investigation of competitive models evaluated thoroughly through a scientific process. Airway Pressure Release Ventilation (APRV) is one of the most studied yet controversial modes of mechanical ventilation that shows promise in experimental and clinical data. Over the last 3 decades APRV has evolved from a rescue strategy to a preemptive lung injury prevention approach with potential to stabilize the lung and restore alveolar homogeneity. However, several obstacles have so far impeded the evaluation of APRV's clinical efficacy in large, randomized trials. For instance, there is no universally accepted standardized method of setting APRV and thus, it is not established whether its effects on clinical outcomes are due to the ventilator mode per se or the method applied. In addition, one distinctive issue that hinders proper scientific evaluation of APRV is the ubiquitous presence of myths and misconceptions repeatedly presented in the literature. In this review we discuss some of these misleading notions and present data to advance scientific discourse around the uses and misuses of APRV in the current literature.

Diaphragm pacing decreases hospital charges for patients with acute cervical spinal cord injury.

BACKGROUND: Cervical spinal cord injury (CSCI) is devastating and costly. Previous research has demonstrated that diaphragm pacing (DPS) is safe and improves respiratory mechanics. This may decrease hospital stays, vent days, and costs. We hypothesized DPS implantation would facilitate liberation from ventilation and would impact hospital charges. METHODS: We performed a retrospective review of patients with acute CSCI between January 2005 and May 2017. Routine demographics were collected. Patients underwent propensity matching based on age, injury severity score, ventilator days, hospital length of stay, and need for tracheostomy. We then adjusted total hospital charges by year using US Bureau of Labor Statistics annual adjusted Medical Care Prices. Bivariate and multivariate linear regression statistics were performed using STATA V.15. RESULTS: Between July 2011 and May 2017, all patients with acute CSCI were evaluated for DPS implantation. 40 patients who had laparoscopic DPS implantation (DPS) were matched to 61 who did not (NO DPS). Following DPS implantation, there was a statistically significant increase in spontaneous Vt compared with NO DPS (+88 mL vs -13 mL; 95% CI 46 to 131 vs -78 to 51 mL, respectively; p=0.004). Median time to liberation after DPS was significantly shorter (10 vs 29 days; 95% CI 6.5 to 13.6 vs 23.1 to 35.3 days; p<0.001). Adjusted hospital charges were significantly lower for DPS on multivariate linear regression models controlling for year of injury, sex, race, injury severity, and age (p=0.003). DISCUSSION: DPS implantation in patients with acute CSCI produces significant improvements in spontaneous Vt and reduces time to liberation, which translated into reduced hospital charges on a risk-adjusted, inflation-adjusted model. DPS implantation for patients with acute CSCI should be considered. LEVEL OF EVIDENCE: Level III.

Diaphragm pacing improves respiratory mechanics in acute cervical spinal cord injury.

BACKGROUND: Cervical spinal cord injury (CSCI) is devastating with ventilator-associated pneumonia being a main driver of morbidity and mortality. Laparoscopic diaphragm pacing implantation (DPS) has been used for earlier liberation from mechanical ventilation. We hypothesized that DPS would improve respiratory mechanics and facilitate liberation. METHODS: We performed a retrospective review of acute CSCI patients between January 2005 and May 2017. Routine demographics were collected. Patients underwent propensity score matching based on age, Injury Severity Score, ventilator days, hospital length of stay, and need for tracheostomy. Patients with complete respiratory mechanics data were analyzed and compared. Those who did not have DPS (NO DPS) had spontaneous tidal volume (Vt) recorded at time of intensive care unit admission, at day 7, and at day 14, and patients who had DPS had spontaneous Vt recorded before and after DPS. Time to ventilator liberation and changes in size of spontaneous Vt for patients while on the ventilator were analyzed. Bivariate and multivariate logistic and linear regression statistics were performed using STATA v10. RESULTS: Between July 2011 and May 2017, 37 patients that had DPS were matched to 34 who did not (NO DPS). Following DPS, there was a statistically significant increase in spontaneous Vt compared with NO DPS (+88 mL vs. -13 mL; 95% confidence interval, 46-131 mL vs. -78 to 51 mL, respectively; p = 0.004). Median time to liberation after DPS was significantly shorter (10 days vs. 29 days; 95% CI, 6.5-13.6 days vs. 23.1-35.3 days; p < 0.001). Liberation prior to hospital discharge was not different between the two groups. The DPS placement was found to be associated with a statistically significant decrease in days to liberation and an increase in spontaneous Vt in multivariate linear regression models. CONCLUSION: The DPS implantation in acute CSCI patients produces significant improvements in spontaneous Vt and reduces time to liberation from mechanical ventilation. Prospective comparative studies are needed to define the clinical benefits and potential cost savings of DPS implantation. LEVEL OF EVIDENCE: Therapeutic IV.

Prolonged Antibiotics for Drains After Spine Injury Instrumentation for Trauma: Not Prophylactic or Necessary.

BACKGROUND: Antibiotics after spine instrumentation are often extended while the surgical drain is in place, particularly for traumatic injuries. We sought to study if continuing antibiotics past 24 hours affected outcomes. METHODS: We performed a retrospective observational study of all patients who underwent spine fixation with hardware and surgical drains for trauma at our institution. We compared the effect of perioperative (≤24 hours of antibiotics) versus prolonged (>24 hours) antibiotics on surgical outcomes. Bivariate and multivariable logistic and linear regression statistics were performed. RESULTS: Three hundred and forty-six patients were included in the analysis. On multivariate analysis, antibiotic duration >24 hours did not predict surgical site infection (odds ratio, 2.68; 95% confidence interval, 0.88-8.10, P = 0.08) or mortality (odds ratio, 0.59; 95% confidence interval, 0.10-3.44; P = 0.56). CONCLUSIONS: Continuing antibiotics past 24 hours after traumatic spine instrumentation was not associated with improved outcomes. A prospective study to verify these findings may be warranted.

Alternative payment models: can (should) trauma care be bundled?

BACKGROUND: Recent legislation repealing the Sustainable Growth Rate mandates gradual replacement of fee for service with alternative payment models (APMs), which will include service bundling. We analyzed the 2 years' experience at our state-designated level I trauma center to determine the feasibility of such an approach for trauma care. METHODS: De-identified data from all injured patients treated by the trauma service during 2014 and 2015 were reviewed to determine individual patient injury profiles. Using these injury profiles we created the 'trauma bundle' by concatenating the highest Abbreviated Injury Scale score for each of the six body regions to produce a single 'signature' of injury by region for every patient. These trauma bundles were analyzed by frequency over 2 years and by each year. The impacts of physiology and resource consumption were evaluated by determination of the correlation of the mean and SD of calculated survival probability (Ps) and intensive care unit length of stay (ICU LOS) for each profile group occurring more than 12 times in 2 years. RESULTS: The 5813 patients treated over 2 years produced 858 distinct injury profiles, only 8% (71) of which occurred more than 12 times in 2 years. Comparison of 2014 and 2015 profiles demonstrated high frequency variation among profiles between the 2 years. Analysis of injury patterns occurring >12 times in 2 years demonstrated an inverse correlation between the mean and SD for Ps (R2=0.68) and a direct correlation for ICU LOS (R2=0.84). DISCUSSION: These data indicate that the disease of injury is too inconsistent a mix of injury pattern and physiologic response to be predictably bundled for an APM. The inverse correlation of increasing SD with increasing ICU LOS and decreasing Ps suggests an opportunity for measurable process improvement. LEVEL OF EVIDENCE: Economic and value-based evaluations, level IV. STUDY TYPE: Economic/decision.