A brief report: the use of high-frequency oscillatory ventilation for severe pulmonary contusion

Optimal ventilator strategies for trauma-related ARDS

BACKGROUND

Acute respiratory distress syndrome (ARDS) was first described in the 1960s and has become a major area of research due to the mortality and morbidity associated with it. ARDS is currently defined using the Berlin Consensus; however, this is not wholly applicable for trauma-related ARDS.

METHODS

A systematic review of the literature was undertaken using the Preferred Reporting for Systematic Reviews and Meta Analyses methodology. The Ovid Medline, Web of Science and PubMed online databases were interrogated for papers published between 1 January 1995 and 31 December 2017.

RESULTS

The literature search yielded a total of 64 papers that fulfilled the search criteria.

CONCLUSIONS

Despite decades of dedicated research into different treatment modalities, ARDS continues to carry a high burden of mortality. The ARDS definitions laid out in the Berlin consensus are not entirely suited to trauma. While trauma-related ARDS represents a small portion of the available research, the evidence continues to favour low tidal volume ventilation as the benchmark for current practice. Positive end expiratory ventilation and airway pressure release ventilation in trauma cohorts may be beneficial; however, the evidence to date does not show this.

Chest trauma: A case for single lung ventilation

Chest trauma is one of the important causes of mortality and morbidity in pediatric trauma patients. The complexity, magnitude, and type of lung injury make it extremely challenging to provide optimal oxygenation and ventilation while protecting the lung from further injury due to mechanical ventilation. Independent lung ventilation is used sporadically in these patients who do not respond to these conventional ventilatory strategies using double-lumen endotracheal tubes, bronchial blocker balloons, etc. However, this equipment may not be easily available in developing countries, especially for pediatric patients. Here, we present a case of severe chest trauma with pulmonary contusion, flail chest, and bronchopleural fistula, who did not respond to conventional lung protective strategies. She was successfully managed with bronchoscopy-guided unilateral placement of conventional endotracheal tube followed by single lung ventilation leading to resolution of a chest injury.

Removal of inflammatory ascites is associated with dynamic modification of local and systemic inflammation along with prevention of acute lung injury: in vivo and in silico studies

BACKGROUND

Sepsis-induced inflammation in the gut/peritoneal compartment occurs early in sepsis and can lead to acute lung injury (ALI). We have suggested that inflammatory ascites drives the pathogenesis of ALI and that removal of ascites with an abdominal wound vacuum prevents ALI. We hypothesized that the time- and compartment-dependent changes in inflammation that determine this process can be discerned using principal component analysis (PCA) and Dynamic Bayesian Network (DBN) inference.

METHODS

To test this hypothesis, data from a previous study were analyzed using PCA and DBN. In that study, two groups of anesthetized, ventilated pigs were subjected to experimental sepsis via intestinal ischemia/reperfusion and placement of a peritoneal fecal clot. The control group (n = 6) had the abdomen opened at 12 h after injury (T12) with attachment of a passive drain. The peritoneal suction treatment (PST) group (n = 6) was treated in an identical fashion except that a vacuum was applied to the peritoneal cavity at T12 to remove ascites and maintained until T48. Multiple inflammatory mediators were measured in ascites and plasma and related to lung function (PaO2/FIO2 ratio and oxygen index) using PCA and DBN.

RESULTS

Peritoneal suction treatment prevented ALI based on lung histopathology, whereas control animals developed ALI. Principal component analysis revealed that local to the insult (i.e., ascites), primary proinflammatory cytokines play a decreased role in the overall response in the treatment group as compared with control. In both groups, multiple, nested positive feedback loops were inferred from DBN, which included interrelated roles for bacterial endotoxin, interleukin 6, transforming growth factor β1, C-reactive protein, PaO2/FIO2 ratio, and oxygen index. von Willebrand factor was an output in control, but not PST, ascites.

CONCLUSIONS

These combined in vivo and in silico studies suggest that in this clinically realistic paradigm of sepsis, endotoxin drives the inflammatory response in the ascites, interplaying with lung dysfunction in a feed-forward loop that exacerbates inflammation and leads to endothelial dysfunction, systemic spillover, and ALI; PST partially modifies this process.

Is the use of high frequency oscillatory ventilator beneficial in managing severe chest injury with massive air leak?

Severe thoracic trauma can be associated with immediate life-threatening injuries including major air leak syndrome that can lead to acute respiratory failure and refractory hypoxaemia. Such injuries invariably require thoracotomy following failure of conventional ventilation strategy and paucity of other non-operative interventions. We describe a case in which we used high frequency oscillatory ventilation (HFOV) as a part of management of such injury and averted the need for thoracotomy.

Acute refractory hypoxemia after chest trauma reversed by high-frequency oscillatory ventilation: a case report

Introduction

Polytrauma often results in significant hypoxemia secondary to direct lung contusion or indirectly through atelectasis, systemic inflammatory response, large volume fluid resuscitation and blood product transfusion. In addition to causing hypoxemia, atelectasis and acute lung injury can lead to right ventricular failure through an acute increase in pulmonary vascular resistance. Mechanical ventilation is often applied, accompanied with recruitment maneuvers and positive end-expiratory pressure in order to recruit alveoli and reverse atelectasis, while preventing excessive alveolar damage. This strategy should lead to the reversal of the hypoxemic condition and the detrimental heart–lung interaction that may occur. However, as described in this case report, hemodynamic instability and intractable alveolar atelectasis sometimes do not respond to conventional ventilation strategies.

Case presentation

We describe the case of a 21-year-old Caucasian man with severe chest trauma requiring surgical interventions, who developed refractory hypoxemia and overt right ventricular failure. After multiple failed attempts of recruitment using conventional ventilation, the patient was ventilated with high-frequency oscillatory ventilation. This mode of ventilation allowed the reversal of the hemodynamic effects of severe hypoxemia and of the acute cor pulmonale. We use this case report to describe the physiological advantages of high-frequency oscillatory ventilation in patients with chest trauma, and formulate the arguments to explain the positive effect observed in our patient.

Conclusions

High-frequency oscillatory ventilation can be used in the context of a blunt chest trauma accompanied by severe hypoxemia due to atelectasis. The positive effect is due to its capacity to recruit the collapsed alveoli and, as a result, the relief of increased pulmonary vascular resistance and subsequently the reversal of acute cor pulmonale. This approach may represent an alternative in case of failure of the conventional ventilation strategy.

Management of pulmonary contusion and flail chest: an Eastern Association for the Surgery of Trauma practice management guideline

BACKGROUND

Despite the prevalence and recognized association of pulmonary contusion and flail chest (PC-FC) as a combined, complex injury pattern with interrelated pathophysiology, the mortality and morbidity of this entity have not improved during the last three decades. The purpose of this updated EAST practice management guideline was to present evidence-based recommendations for the treatment of PC-FC.

METHODS

A query was conducted of MEDLINE, Embase, PubMed and Cochrane databases for the period from January 1966 through June 30, 2011. All evidence was reviewed and graded by two members of the guideline committee. Guideline formulation was performed by committee consensus.

RESULTS

Of the 215 articles identified in the search, 129 were deemed appropriate for review, grading, and inclusion in the guideline. This practice management guideline has a total of six Level 2 and eight Level 3 recommendations.

CONCLUSION

Patients with PC-FC should not be excessively fluid restricted but should be resuscitated to maintain signs of adequate tissue perfusion. Obligatory mechanical ventilation in the absence of respiratory failure should be avoided. The use of optimal analgesia and aggressive chest physiotherapy should be applied to minimize the likelihood of respiratory failure. Epidural catheter is the preferred mode of analgesia delivery in severe flail chest injury. Paravertebral analgesia may be equivalent to epidural analgesia and may be appropriate in certain situations when epidural is contraindicated.A trial of mask continuous positive airway pressure should be considered in alert patients with marginal respiratory status. Patients requiring mechanical ventilation should be supported in a manner based on institutional and physician preference and separated from the ventilator at the earliest possible time. Positive end-expiratory pressure or continuous positive airway pressure should be provided. High-frequency oscillatory ventilation should be considered for patients failing conventional ventilatory modes. Independent lung ventilation may also be considered in severe unilateral pulmonary contusion when shunt cannot be otherwise corrected.Surgical fixation of flail chest may be considered in cases of severe flail chest failing to wean from the ventilator or when thoracotomy is required for other reasons. Self-activating multidisciplinary protocols for the treatment of chest wall injuries may improve outcome and should be considered where feasible.Steroids should not be used in the therapy of pulmonary contusion. Diuretics may be used in the setting of hydrostatic fluid overload in hemodynamically stable patients or in the setting of known concurrent congestive heart failure.

A two-compartment mathematical model of endotoxin-induced inflammatory and physiologic alterations in swine

OBJECTIVE

To gain insights into individual variations in acute inflammation and physiology.

DESIGN

Large-animal study combined with mathematical modeling.

SETTING

Academic large-animal and computational laboratories.

SUBJECTS

Outbred juvenile swine.

INTERVENTIONS

Four swine were instrumented and subjected to endotoxemia (100 µg/kg), followed by serial plasma sampling.

MEASUREMENTS AND MAIN RESULTS

Swine exhibited various degrees of inflammation and acute lung injury, including one death with severe acute lung injury (PaO(2)/FIO(2) ratio μ200 and static compliance μ10 L/cm H(2)O). Plasma interleukin-1β, interleukin-4, interleukin-6, interleukin-8, interleukin-10, tumor necrosis factor-α, high mobility group box-1, and NO(2)/NO(3) were significantly (p μ .05) elevated over the course of the experiment. Principal component analysis was used to suggest principal drivers of inflammation. Based in part on principal component analysis, an ordinary differential equation model was constructed, consisting of the lung and the blood (as a surrogate for the rest of the body), in which endotoxin induces tumor necrosis factor-α in monocytes in the blood, followed by the trafficking of these cells into the lung leading to the release of high mobility group box-1, which in turn stimulates the release of interleukin-1β from resident macrophages. The ordinary differential equation model also included blood pressure, PaO(2), and FIO(2), and a damage variable that summarizes the health of the animal. This ordinary differential equation model could be fit to both inflammatory and physiologic data in the individual swine. The predicted time course of damage could be matched to the oxygen index in three of the four swine.

CONCLUSIONS

The approach described herein may aid in predicting inflammation and physiologic dysfunction in small cohorts of subjects with diverse phenotypes and outcomes.

High-frequency oscillation as a rescue strategy for brain-injured adult patients with acute lung injury and acute respiratory distress syndrome

Acute lung injury and acute respiratory distress syndrome (ARDS) occur frequently in brain-injured patients. Single organ dysfunction ventilator strategies result in a conflict between lung protective ventilation and the prevention of secondary neurological insult(s). The objectives of this study were to determine if clinical and physiological benefits of high-frequency oscillatory ventilation (HFOV) exist compared to conventional ventilation and to determine what data there are on the effects of HFOV on cerebral perfusion pressure and intracranial pressure. Systematic review was designed. An optimally sensitive search strategy was used that included; OVID MEDLINE, OVID EMBASE, Cochrane Clinical Trials Register, and hand searching of references of retrieved articles and proceedings of meetings. Study selection includes published randomized controlled trials comparing HFOV with conventional ventilation in adults with ARDS and observational studies of the use of HFOV in adults with ARDS and traumatic brain injury (TBI). Both authors reviewed all trials. A data extraction form was used. In adults with ARDS no mortality benefit has been shown with HFOV, oxygenation improves, arterial partial pressure of CO(2) may increase and there is no change in mean arterial blood pressure. There are few data describing HFOV in adults with TBI. In the small, low quality, studies that have been reported there have not been uncontrollable changes in intracranial pressure. HFOV has not been shown to have any mortality benefit in adults with ARDS. There are insufficient data to clarify the role, or safety, of HFOV in adults with TBI and concurrent ARDS.

Pulmonary contusion: an update on recent advances in clinical management

Pulmonary contusion is a common finding after blunt chest trauma. The physiologic consequences of alveolar hemorrhage and pulmonary parenchymal destruction typically manifest themselves within hours of injury and usually resolve within approximately 7 days. Clinical symptoms, including respiratory distress with hypoxemia and hypercarbia, peak at about 72 h after injury. The timely diagnosis of pulmonary contusion requires a high degree of clinical suspicion when a patient presents with trauma caused by an appropriate mechanism of injury. The clinical diagnosis of acute parenchymal lung injury is usually confirmed by thoracic computed tomography, which is both highly sensitive in identifying pulmonary contusion and highly predictive of the need for subsequent mechanical ventilation. Management of pulmonary contusion is primarily supportive. Associated complications such as pneumonia, acute respiratory distress syndrome, and long-term pulmonary disability, however, are frequent sequelae of these injuries.

Utilisation of high-frequency oscillatory ventilation in blunt thoracic trauma

Blunt thoracic trauma patients are at high risk of mortality when conventional mechanical ventilation fails to sustain respiratory function.We provide an overview of high-frequency oscillatory ventilation (HFOV) as a potential rescue therapy for such patients.Although few studies have examined the utilisation of HFOV specifically for blunt thoracic trauma, available evidence indicates that this ventilatory strategy may be beneficial when instituted relative early in the management of patients with severe pulmonary contusion or blunt thoracic trauma with superimposed acute respiratory distress syndrome.

Mechanical ventilation in trauma

PURPOSE OF REVIEW

The purpose of this review is to evaluate new concepts in mechanical ventilation in trauma. We begin with the keystone of physiology prior to embarking on a discussion of several new modes of mechanical ventilation. We will discuss the use of noninvasive ventilation as a mode to prevent intubation and then go on to airway pressure release ventilation, high-frequency oscillatory ventilation, and computer-based, closed loop ventilation.

RECENT FINDINGS

The importance of preventing further injury in mechanical ventilation lies at the heart of the introduction of several new strategies of mechanical ventilation. New modes of ventilation have been developed to provide lung recruitment and alveolar stabilization at the lowest possible pressure.

SUMMARY

The old modes of continuous positive airway pressure and bilevel positive airway pressure have been actively introduced in clinical practice in the case of trauma patients. Used with proper pain management protocols, there has been a decrease in the incidence of intubation in blunt thoracic trauma. Airway pressure release ventilation has been gaining a role in the management of thoracic injury and may lead to less incidence of physiologic trauma to mechanically ventilated patients. High-frequency oscillatory ventilation has been shown to be effective in patient care by its ability to open and recruit the lung in trauma patients and in those with acute respiratory distress syndrome but it may not have a role in patients with inhalational injury. Closed loop ventilation is a technology that may better control major pulmonary parameters and lead to more rapid titration from the ventilator to spontaneous breathing.

Air transport of patients with severe lung injury: development and utilization of the Acute Lung Rescue Team

BACKGROUND

Critical Care Air Transport Teams (CCATTs) are an integral component of modern casualty care, allowing early transport of critically ill and injured patients. Aeromedical evacuation of patients with significant pulmonary impairment is sometimes beyond the scope of CCATT because of limitations of the transport ventilator and potential for further respiratory deterioration in flight. The Acute Lung Rescue Team (ALRT) was developed to facilitate transport of these patients out of the combat theater.

METHODS

The United States TRANSCOM Regulation and Command/Control Evacuation System and the United States Army Institute of Surgical Research Joint Theater Trauma Registry databases were reviewed for all critical patients transported out of theater between November 2005 and March 2007. Patient demographics, diagnosis, and clinical history were abstracted and ALRT patients were compared with CCATT patients.

RESULTS

The ALRT was activated for 11 patients during the study period. Five patients were transported as a result of these activations. Trauma-related diagnoses were responsible for 82% of these requests. ALRT missions comprised 0.6% of all critical patient movements out of the combat theater and 1% of ventilator transports. Average FIO2 was 0.92 +/- 0.11 for ALRT patients and 0.53 +/- 0.14 for CCATT patients (p = 0.005). ALRT patients required a mean positive end expiratory pressure of 19.0 cm H2O +/- 2.2 cm H2O compared with 6.5 cm H2O +/- 2.4 cm H2O in the CCATT group (p = 0.002).

CONCLUSIONS

Lung injury in the combat theater severe enough to exceed the capability of CCATT transport is uncommon. Patients for whom ALRT was activated had significantly higher positive end expiratory pressure and FIO2 than those transported by CCATT. One-fourth of patients for whom ALRT was considered died before the team could be launched; transport may have been a futile consideration in these patients. Patients with even severe acute respiratory distress syndrome can be successfully transported by experienced, equipped specialty teams.