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Bedside respiratory physiology to detect risk of lung injury in acute respiratory distress syndrome.Current Opinion in Critical Care Feb 2019The most effective strategies for treating the patient with acute respiratory distress syndrome center on minimizing ventilation-induced lung injury (VILI). Yet, current... (Review)
Review
PURPOSE OF REVIEW
The most effective strategies for treating the patient with acute respiratory distress syndrome center on minimizing ventilation-induced lung injury (VILI). Yet, current standard-of-care does little to modify mechanical ventilation to patient-specific risk. This review focuses on evaluation of bedside respiratory mechanics, which when interpreted in patient-specific context, affords opportunity to individualize lung-protective ventilation in patients with acute respiratory distress syndrome.
RECENT FINDINGS
Four biophysical mechanisms of VILI are widely accepted: volutrauma, barotrauma, atelectrauma, and stress concentration. Resulting biotrauma, that is, local and systemic inflammation and endothelial activation, may be thought of as the final common pathway that propagates VILI-mediated multiorgan failure. Conventional, widely utilized techniques to assess VILI risk rely on airway pressure, flow, and volume changes, and remain essential tools for determining overdistension of aerated lung regions, particularly when interpreted cognizant of their limitations. Emerging bedside tools identify regional differences in mechanics, but further study is required to identify how they might best be incorporated into clinical practice.
SUMMARY
Quantifying patient-specific risk of VILI requires understanding each patient's pulmonary mechanics in context of biological predisposition. Tailoring support at bedside according to these factors affords the greatest opportunity to date for mitigating VILI and alleviating associated morbidity.
Topics: Barotrauma; Humans; Inflammation; Lung; Lung Injury; Multiple Organ Failure; Positive-Pressure Respiration; Respiration, Artificial; Respiratory Distress Syndrome; Respiratory Mechanics; Tidal Volume; Ventilator-Induced Lung Injury
PubMed: 30531534
DOI: 10.1097/MCC.0000000000000579 -
Respiratory Care Jan 2021Studies evaluating neuromuscular blocking agents (NMBAs) in the management of ARDS have produced inconsistent results in terms of their effect on mortality. The purpose... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Studies evaluating neuromuscular blocking agents (NMBAs) in the management of ARDS have produced inconsistent results in terms of their effect on mortality. The purpose of this systematic review and meta-analysis was to evaluate differences in mortality comparing subjects with ARDS who received NMBA to those who received placebo or usual care.
METHODS
We searched Ovid, MEDLINE, Embase, CINAHL, Cochrane, Scopus, and Web of Science for randomized controlled trials evaluating administration of NMBAs in subjects with ARDS.
RESULTS
We included 6 studies ( = 1,558 subjects) from 1,814 abstracts identified by our search strategy. The use of early, continuous-infusion NMBAs reduces the risk of short-term (ie, 21-28-d) mortality (relative risk 0.71 [95% CI 0.52-0.98], = .030, = 60%) in subjects with ARDS but does not reduce the risk of long-term (ie, 90-d) mortality (relative risk 0.81 [95% CI 0.64-1.04], = .10, = 54%). NMBAs decreased the risk of barotrauma (relative risk 0.55 [95% CI 0.35-0.85], = .008, = 0%) and pneumothorax (relative risk 0.46 [95% CI 0.28-0.77], = .003, = 0%) compared to control.
CONCLUSIONS
In subjects with ARDS, early use of NMBAs improves oxygenation, reduces the incidence of ventilator-induced lung injury, and decreases 21-28-d mortality, but it does not improve 90-d mortality. NMBAs should be considered for select patients with moderate-to-severe ARDS for short durations.
Topics: Barotrauma; Humans; Lung; Neuromuscular Blocking Agents; Respiration, Artificial; Respiratory Distress Syndrome; Time Factors
PubMed: 32843506
DOI: 10.4187/respcare.07849 -
The Journal of Surgical Research May 2023To establish a blast- and fragment-induced pelvic injury animal model in rabbits, observe its injury characteristics, and explore the effects of hemostatic resuscitation...
INTRODUCTION
To establish a blast- and fragment-induced pelvic injury animal model in rabbits, observe its injury characteristics, and explore the effects of hemostatic resuscitation combined with damage control surgery (DCS) with respect to this injury model.
METHODS
Forty-eight rabbits were randomly allocated to four groups: group A rabbits were subjected to pelvic injury, group B rabbits to pelvic injury + DCS, group C rabbits to pelvic injury + DCS + resuscitation with Hextend, and group D rabbits to pelvic injury + DCS + Hextend + hemostatic resuscitation with tranexamic acid, fibrinogen concentrate, and prothrombin complex concentrate. Simulated blast and fragment-induced pelvic injury was produced by a custom-made machine. We implemented CT scanning and necropsy to assess the injury state and calculated the coefficient of variation (CV) of the cumulative abbreviated injury scale (AIS) to assess the reproducibility of the animal model. Immediately after instrumentation (0 h), and 1 h, 2 h, 4 h, and 8 h after injury, blood samples were taken for laboratory tests.
RESULTS
We found that severe pelvic injury was produced with an AIS CV value of 10.32%, and the rabbits demonstrated severe physiologic impairment and coagulo-fibrinolytic derangements with high mortality. In rabbits of group D, however, physiologic and coagulo-fibrinolytic parameters were significantly enhanced with improved organ function and lowered mortality when compared with the other three groups.
CONCLUSIONS
We herein established in rabbits a blast- and fragment-induced pelvic injury animal model that exhibited high reproducibility, and we demonstrated that hemostatic resuscitation plus DCS was effective in improving the outcome.
Topics: Animals; Rabbits; Blast Injuries; Fibrinogen; Hemostasis; Hemostatics; Hydroxyethyl Starch Derivatives; Reproducibility of Results; Resuscitation
PubMed: 36680876
DOI: 10.1016/j.jss.2022.12.031 -
Journal of Visualized Experiments : JoVE Sep 2017Exposure to blast events can cause severe trauma to vital organs such as the lungs, ears, and brain. Understanding the mechanisms behind such blast-induced injuries is...
Exposure to blast events can cause severe trauma to vital organs such as the lungs, ears, and brain. Understanding the mechanisms behind such blast-induced injuries is of great importance considering the recent trend towards the use of explosives in modern warfare and terrorist-related incidents. To fully understand blast-induced injury, we must first be able to replicate such blast events in a controlled environment using a reproducible method. In this technique using shock tube equipment, shock waves at a range of pressures can be propagated over live cells grown in 2D, and markers of cell viability can be immediately analyzed using a redox indicator assay and the fluorescent imaging of live and dead cells. This method demonstrated that increasing the peak blast overpressure to 127 kPa can stimulate a significant drop in cell viability when compared to untreated controls. Test samples are not limited to adherent cells, but can include cell suspensions, whole-body and tissue samples, through minor modifications to the shock tube setup. Replicating the exact conditions that tissues and cells experience when exposed to a genuine blast event is difficult. Techniques such as the one presented in this article can help to define damage thresholds and identify the transcriptional and epigenetic changes within cells that arise from shock wave exposure.
Topics: Animals; Blast Injuries; Rats; Rats, Sprague-Dawley
PubMed: 28994788
DOI: 10.3791/55618 -
Anaesthesiology Intensive Therapy 2022There is increased incidence of barotrauma in COVID-19 patients, probably due to disease pathology, oxygen therapy and coughing. We aimed to retrospectively compare the...
BACKGROUND
There is increased incidence of barotrauma in COVID-19 patients, probably due to disease pathology, oxygen therapy and coughing. We aimed to retrospectively compare the characteristics, associations and outcomes of COVID-19 patients with and without barotrauma in the intensive care unit (ICU).
METHODS
All adults admitted between October 1st and December 31st 2020 in the ICUs of a COVID-19 hospital were retrospectively analysed for presence of a 'barotrauma event' (presence of at least one of pneumothorax, pneumomediastinum, subcutaneous emphysema or bronchopleural fistula). A control group was formed by matching each case to a patient belonging to the same gender and age range from the remaining patients in the cohort, i.e., those without barotrauma. Demographic details, ICU stay details, details of oxygen therapy and ventilation, and outcomes were noted and compared.
RESULTS
Of 827 patients, 30 patients (3.6%) developed barotrauma events. The typical patient was middle aged (median age 55.5 years) and male (73.3%). The mortality rate was significantly higher in the barotrauma group (83.3% vs. 43.3%, P < 0.001), and odds of survival decreased by 85% if barotrauma occurred (OR 0.15; 95% CI: 0.46-0.51). Patients who developed barotrauma spent a longer time on a high-flow nasal cannula (median 6.7 vs. 1.73 days, P = 0.04), and mechanical ventilation (median 9.54 vs. 0.867 days, P < 0.001), and had a longer ICU stay (median 15.5 vs. 9 days, P = 0.014). The most common event was pneumothorax (26/30).
CONCLUSIONS
Barotrauma in the COVID-19 ICU is associated with prolonged ICU stay, higher odds of mortality and longer duration spent on mechanical ventilation and a high-flow nasal cannula. Key words: barotrauma, ICU, COVID-19, mortality, pneumothorax.
Topics: Adult; Barotrauma; COVID-19; Case-Control Studies; Critical Illness; Humans; Male; Middle Aged; Retrospective Studies
PubMed: 35359137
DOI: 10.5114/ait.2022.114034 -
Blast Injury in the Spine: Dynamic Response Index Is Not an Appropriate Model for Predicting Injury.Clinical Orthopaedics and Related... Sep 2015Improvised explosive devices are a common feature of recent asymmetric conflicts and there is a persistent landmine threat to military and humanitarian personnel.... (Comparative Study)
Comparative Study Review
BACKGROUND
Improvised explosive devices are a common feature of recent asymmetric conflicts and there is a persistent landmine threat to military and humanitarian personnel. Assessment of injury risk to the spine in vehicles subjected to explosions was conducted using a standardized model, the Dynamic Response Index (DRI). However, the DRI was intended for evaluating aircraft ejection seats and has not been validated in blast conditions.
QUESTIONS/PURPOSES
We asked whether the injury patterns seen in blast are similar to those in aircraft ejection and therefore whether a single injury prediction model can be used for both situations.
METHODS
UK military victims of mounted blast (seated in a vehicle) were identified from the Joint Theatre Trauma Registry. Each had their initial CT scans reviewed to identify spinal fractures. A literature search identified a comparison population of ejected aircrew with spinal fractures. Seventy-eight blast victims were identified with 294 fractures. One hundred eighty-nine patients who had sustained aircraft ejection were identified with 258 fractures. The Kruskal-Wallis test was used to compare the population injury distributions and Fisher's exact test was used to assess differences at each spinal level.
RESULTS
The distribution of injuries between blast and ejection was not similar. In the cervical spine, the relative risk of injury was 11.5 times higher in blast; in the lumbar spine the relative risk was 2.9 times higher in blast. In the thoracic spine, the relative risk was identical in blast and ejection. At most individual vertebral levels including the upper thoracic spine, there was a higher risk of injury in the blast population, but the opposite was true between T7 and T12, where the risk was higher in aircraft ejection.
CONCLUSIONS
The patterns of injury in blast and aircraft are different, suggesting that the two are mechanistically dissimilar. At most vertebral levels there is a higher relative risk of fracture in the blast population, but at the apex of the thoracic spine and in the lower thoracic spine, there is a higher risk in ejection victims. The differences in relative risk at different levels, and the resulting overall different injury patterns, suggest that a single model cannot be used to predict the risk of injury in ejection and blast.
CLINICAL RELEVANCE
A new model needs to be developed to aid in the design of mine-protected vehicles for future conflicts.
Topics: Accidents, Aviation; Accidents, Traffic; Blast Injuries; Cervical Vertebrae; Explosions; Humans; Lumbar Vertebrae; Military Medicine; Predictive Value of Tests; Registries; Risk Assessment; Risk Factors; Spinal Fractures; Thoracic Vertebrae; Tomography, X-Ray Computed; United Kingdom
PubMed: 25828945
DOI: 10.1007/s11999-015-4281-2 -
Scientific Reports Nov 2023The expansion and potential rupture of the swim bladder due to rapid decompression, a major cause of barotrauma injury in fish that pass through turbines and pumps, is...
The expansion and potential rupture of the swim bladder due to rapid decompression, a major cause of barotrauma injury in fish that pass through turbines and pumps, is generally assumed to be governed by Boyle's Law. In this study, two swim bladder expansion models are presented and tested in silico. One based on the quasi-static Boyle's Law, and a Modified Rayleigh Plesset Model (MRPM), which includes both inertial and pressure functions and was parametrised to be representative of a fish swim bladder. The two models were tested using a range of: (1) simulated and (2) empirically derived pressure profiles. Our results highlight a range of conditions where the Boyle's Law model (BLM) is inappropriate for predicting swim bladder size in response to pressure change and that these conditions occur in situ, indicating that this is an applied and not just theoretical issue. Specifically, these conditions include any one, or any combination, of the following factors: (1) when rate of pressure change is anything but very slow compared to the resonant frequency of the swim bladder; (2) when the nadir pressure is near or at absolute zero; and (3) when a fish experiences liquid tensions (i.e. negative absolute pressures). Under each of these conditions, the MRPM is more appropriate tool for predicting swim bladder size in response to pressure change and hence it is a better model for quantifying barotrauma in fish.
Topics: Animals; Barotrauma; Pressure
PubMed: 37926724
DOI: 10.1038/s41598-023-46125-9 -
BMJ Military Health Aug 2023'Primary' blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. With continued...
'Primary' blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. With continued experimental focus on PBI mechanisms, recently on blast traumatic brain injury, meaningful test outcomes rely on appropriate simulated conditions. Selected PBI predictive criteria (grouped into those affecting the auditory system, pulmonary injuries and brain trauma) are combined and plotted to provide rationale for generating clinically relevant loading conditions. Using blast engineering theory, explosion characteristics including blast wave parameters and fireball dimensions were calculated for a range of charge masses assuming hemispherical surface detonations and compared with PBI criteria. While many experimental loading conditions are achievable, this analysis demonstrated limits that should be observed to ensure loading is clinically relevant, realistic and practical. For PBI outcomes sensitive only to blast overpressure, blast scaled distance was demonstrated to be a useful parameter for guiding experimental design as it permits flexibility for different experimental set-ups. This analysis revealed that blast waves should correspond to blast scaled distances of 1.75
Topics: Humans; Explosions; Blast Injuries; Brain Injuries, Traumatic
PubMed: 34035162
DOI: 10.1136/bmjmilitary-2021-001796 -
Scientific Reports Sep 2018Understanding the mechanisms underlying traumatic neural injury and the sequelae of events in the acute phase is important for deciding on the best window of therapeutic...
Understanding the mechanisms underlying traumatic neural injury and the sequelae of events in the acute phase is important for deciding on the best window of therapeutic intervention. We hypothesized that evoked potentials (EP) recorded from the cerebellar cortex can detect mild levels of neural trauma and provide a qualitative assessment tool for progression of cerebellar injury in time. The cerebellar local field potentials evoked by a mechanical tap on the hand and collected with chronically implanted micro-ECoG arrays on the rat cerebellar cortex demonstrated substantial changes both in amplitude and timing as a result of blast-wave induced injury. The results revealed that the largest EP changes occurred within the first day of injury, and partial recoveries were observed from day-1 to day-3, followed by a period of gradual improvements (day-7 to day-14). The mossy fiber (MF) and climbing fiber (CF) mediated components of the EPs were affected differentially. The behavioral tests (ladder rung walking) and immunohistological analysis (calbindin and caspase-3) did not reveal any detectable changes at these blast pressures that are typically considered as mild (100-130 kPa). The results demonstrate the sensitivity of the electrophysiological method and its use as a tool to monitor the progression of cerebellar injuries in longitudinal animal studies.
Topics: Animals; Behavior, Animal; Blast Injuries; Cerebellar Cortex; Electrophysiological Phenomena; Evoked Potentials; Nerve Fibers; Rats
PubMed: 30206255
DOI: 10.1038/s41598-018-31728-4 -
Chinese Journal of Traumatology =... May 2023High explosives are used to produce blast waves to study their biological effects. The lungs are considered as the critical target organ in blast-effect studies. The...
PURPOSE
High explosives are used to produce blast waves to study their biological effects. The lungs are considered as the critical target organ in blast-effect studies. The degree of lung hemorrhaging is related to both the explosive power and the increased lung weight. We studied the characteristics of the biological effects from an air explosion of a thermobaric bomb in a high-altitude environment and the lethality and lung injury severity of goats in different orientations and distances.
METHODS
Goats were placed at 2.5, 3, 4, and 5 m from the explosion center and exposed them to an air blast at an altitude of 4700-meter. A group of them standing oriented to the right side and the other group seated facing the explosion center vertically. The lung injuries were quantified according to the percentage of surface area contused, and using the pathologic severity scale of lung blast injury (PSSLBI) to score the 4 injury categories (slight, moderate, serious and severe) as 1, 2, 3, and 4, respectively. The lung coefficient (lung weight [g]/body weight [kg]) was the indicator of pulmonary edema and was related to lung injury severity. Blast overpressure data were collected using blast test devices placed at matching locations to represent loadings to goats. All statistical analyses were performed using SPSS, version 26.0, statistical software (SPSS, Inc., Chicago, IL, USA).
RESULTS
In total, 127 goats were involved in this study. Right-side-standing goats had a significantly higher mortality rate than those seated vertical-facing (p < 0.05). At the 2.5 m distance, the goat mortality was nearly 100%, whereas at 5 m, all the goats survived. Lung injuries of the right-side-standing goats were 1 - 2 grades more serious than those of seated goats at the same distances, the scores of PSSLBI were significantly higher than the seated vertical-facing goats (p < 0.05). The lung coefficient of the right-side-standing goats were significantly higher than those of seated vertical-facing (p < 0.05). Mortality, PSSLBI, and the lung coefficient results indicated that the right-side-standing goats experienced severer injuries than the seated vertical-facing goats, and the injuries were lessened as the distance increased. The blast overpressure was consistent with these results.
CONCLUSION
The main killing factors of the thermobaric bomb in the high-altitude environment were blast overpressure, blast wind propulsions and burn. The orientation and distances of the goats significantly affected the blast injury severity. These results may provide a research basis for diagnosing, treating and protecting against injuries from thermobaric explosions.
Topics: Animals; Lung Injury; Blast Injuries; Goats; Explosions; Lung
PubMed: 36344366
DOI: 10.1016/j.cjtee.2022.09.001