High frequency oscillatory ventilation for surgical patients with acute respiratory distress syndrome

Blunt aortic injury: risk factors and impact of surgical approaches

PURPOSE

This study reviews our 17-year experience of managing blunt traumatic aortic injury (BTAI).

METHODS

We analyzed information collected retrospectively from a tertiary trauma center.

RESULTS

Between October 1995 and June 2012, 88 patients (74 male and 14 female) with a mean age of 39.9 ± 17.9 years (range 15-79 years) with proven BTAI were enrolled in this study. Their GCS, ISS, and RTS scores were 12.9 ± 3.7, 29.2 ± 9.8, and 6.9 ± 1.4, respectively. Twenty-one (23.8 %) patients were managed non-operatively, 49 (55.7 %) with open surgical repair, and 18 (20.5 %) with endovascular repair. The in-hospital mortality rate was 17.1 % (15/81) and there were no deaths in the endovascular repair group. The mean follow-up period was 39.9 ± 44.2 months. The survivors of blunt aortic injury had lower ISS, RTS, TRISS, and serum creatinine level and lower rate of massive blood transfusion, shock, and intubation than the patients who died, despite higher rates of endovascular repair, hemoglobin, and GCS on presentation. The degree of aortic injury, different therapeutic options, GCS, shock presentation, and intubation on arrival all had significant impacts on outcome.

CONCLUSIONS

Shock, aortic injury severity, coexisting trauma severity, and different surgical approaches impact survival. Endovascular repair achieves a superior mid-term result and is a reasonable option for treating BTAI.

Current knowledge of acute lung injury and acute respiratory distress syndrome

Acute lung injury/acute respiratory distress syndrome (ALI/ARDS) continues to be a major cause of mortality in adult and pediatric critical care medicine. This article discusses the pulmonary sequelae associated with ALI and ARDS, the support of ARDS with mechanical ventilation, available adjunctive therapies, and experimental therapies currently being tested. It is hoped that further understanding of the fundamental biology, improved identification of the patient's inflammatory state, and application of therapies directed at multiple sites of action may ultimately prove beneficial for patients suffering from ALI/ARDS.

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.

Resolution of organ functional scores to predict the outcome in adult acute respiratory distress syndrome patients receiving high-frequency oscillatory ventilation

BACKGROUND

High-frequency oscillatory ventilation (HFOV) may be used as a rescue therapy for adults with acute respiratory distress syndrome who have failed conventional ventilation (CV). We undertook a prospective study to investigate the determinants of mortality and the sequential evolution of organ failures in HFOV-treated adult acute respiratory distress syndrome patients.

METHODS

The indication for HFOV was severe oxygenation failure (PaO2/FiO2 <120 mm Hg) while receiving aggressive CV support (defined by either PaO2 ≤65 mm Hg with FiO2 ≥0.6 when positive end-expiratory pressures >10 cmH2O or plateau airway pressure ≥35 cm H2O). Demographic, clinical, and physiologic data were collected prospectively (May 2007-July 2009). Organ System Failure (OSF), Sequential Organ Failure Assessment (SOFA), and Multiple Organ Dysfunction (MOD) scores were recorded during and after HFOV application. Additional outcome measures included HFOV successful weaning rate, cause of failure, complications, survival rate, and cause of death.

RESULTS

The intensive care unit mortality rate was 62% (21 of 34). Survivors had a significantly shorter CV time before HFOV than nonsurvivors (32.8 hours ± 16.7 hours vs. 47.9 hours ± 26.2 hours, p = 0.049). Survivors had significantly lower baseline lung injury scores, OSF, SOFA, and MOD scores than nonsurvivors. After HFOV, the OSF, SOFA, and MOD scores were significantly decreased for survivors, particularly from day 3 onward.

CONCLUSIONS

Survivors had early improvements in OSF scores after HFOV application. Organ failure system scoring may be used for deciding on HFOV initiation and for evaluating the effects of HFOV.

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.

Clinical application of ventilator modes: Ventilatory strategies for lung protection

INTRODUCTION

Identification of the mortality reducing effect of lung protective ventilation using low tidal volumes and pressure limitation is one of the biggest advances in the application of mechanical ventilation. Yet studies continue to demonstrate low adoption of this style of ventilation. Critical care nurses in Australia and New Zealand have a high level of responsibility and autonomy for mechanical ventilation and weaning practices and therefore require in-depth knowledge of ventilator technology, its clinical application and the current evidence for effective ventilation strategies.

AIM

To present an overview of current knowledge and research relating to lung protective ventilation.

METHOD

A multidatabase literature search using the terms protective ventilation, open lung, high frequency oscillatory ventilation, airway pressure release ventilation, and weaning.

RESULTS

Based on clinical trials and physiological evidence lung protective strategies using low tidal volumes and moderate levels of PEEP have been recommended as strategies to prevent tidal alveolar collapse and overdistension in patients with ALI/ARDS. Evidence now suggests these strategies may also be beneficial in patients with normal lungs. Lung protective ventilation may be applied with either volume or pressure-controlled ventilation. Pressure-controlled ventilation allows regulation over injurious peak inspiratory pressures; however no study has identified the superiority of pressure-controlled ventilation over low tidal volume strategies using volume-control. Other lung protective ventilation strategies include moderate to high positive-end expiratory pressure, recruitment manoeuvres, high frequency oscillatory ventilation, and airway pressure release ventilation though definitive trials identifying consistently improved patient outcomes are still needed. No ventilation strategy can be more lung protective than the timely discontinuation of mechanical ventilation. Despite the above recommendations, evidence suggests the decision to commence weaning and attempt extubation continue to be delayed. Critical care nurses play a vital role in the recognition of patients capable of spontaneous breathing and ready for extubation. Organisational interventions such as weaning protocols as well as computerised weaning systems may have less effect when nurses are able to manage weaning processes effectively.

CONCLUSIONS

Lung protective ventilatory strategies are not consistently applied and weaning and extubation continue to be delayed. Critical care nurses need to establish a strong knowledge base to promote effective and appropriate management of patients requiring mechanical ventilation.

High-frequency oscillatory ventilation in adults: clinical considerations and management priorities

Recently, there has been renewed interest in high-frequency oscillatory ventilation (HFOV) as a lung-protective strategy in adults. It limits overdistension and prevents cyclic collapse by maintaining end-expiratory lung volume. Studies have shown that HFOV is safely tolerated in the adult population and may offer more benefit if applied early in the course of disease. These findings have implications for clinicians as the use of HFOV may increase in the coming decade. Gas transport mechanisms, ventilator settings, patient monitoring, and clinical considerations for HFOV are substantially different from conventional mechanical ventilation. This article reviews management strategies and monitoring priorities currently recommended for management of adults receiving HFOV.

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

BACKGROUND

Severe pulmonary contusions are a common cause of acute respiratory distress syndrome (ARDS) and are associated with significant morbidity. High frequency oscillatory ventilation (HFOV) is a ventilatory mode that employs a lung protective strategy consistent with the ARDSNet low tidal volume ventilation strategy and may result in reduced morbidity. The objective of this report is to examine the impact of HFOV on blunt trauma patients with severe pulmonary contusions who failed or were at a high risk of failing conventional mechanical ventilation.

METHODS

We undertook a retrospective chart review of all patients at our institution who received HFOV for severe pulmonary contusions. Patients were placed on HFOV when their mean airway pressure (mP(aw)) surpassed 30 cm H2O and their FIO2 was greater than 0.6. Baseline demographic data including injury severity score (ISS), length of time requiring HFOV, total ventilator days, and inhospital mortality were collected. Serial determinations of oxygenation index (OI) and the PaO2/FIO2 ratio (P/F) were made up to 72 hours after initiation of HFOV. A linear mixed model was used to analyze the slope (beta) of the regression line of P/F versus time and that of OI versus time.

RESULTS

Seventeen patients were identified who underwent HFOV for ARDS due primarily to pulmonary contusions. Mean ISS was 36.6, mean APACHE II score was 21.7, and the mean time before initiation of HFOV was 2.0 days. P/F increased significantly after HFOV was initiated (beta = 12.1; 95% confidence interval 7.9 to 16.4, p < 0.001). OI significantly decreased after HFOV implementation (beta = -1.8; 95% confidence interval -2.3 to -1.3, p < 0.001). Mortality rate was 17.6%.

CONCLUSIONS

The early use of HFOV appears to be safe and efficacious in blunt trauma patients sustaining pulmonary contusions, and results in a rapid improvement in OI and the P/F ratio.

High frequency oscillatory ventilation in children: experience of a medical center in Taiwan

BACKGROUND/PURPOSE

Data about the effectiveness of high frequency oscillatory ventilation (HFOV) in children with respiratory failure are limited. This study investigated the efficacy and prognostic factors of this treatment.

METHODS

Children between 2 months and 18 years of age who received HFOV between January 2000 and September 2006 in a tertiary care center were enrolled in this retrospective study.

RESULTS

Thirty-six HFOV treatments were given to 33 patients (twice in one patient and three times in another patient) at a mean age of 5.4 +/- 5.0 years. HFOV was used as a rescue after conventional mechanical ventilation (CMV) for 4.4 +/- 4.2 days. The mean duration of HFOV was 7.6 +/- 7.9 days. The most common indication for HFOV was oxygenation failure, which was due to pneumonia with acute respiratory distress syndrome in 15 (45.5%), severe lobar pneumonia in nine (27.3%), pulmonary hemorrhage in eight (24.2%) and pneumothorax in one (3%). PaCO2 was significantly improved 4 hours after HFOV and the PaO2/FiO2 ratio increased significantly 12 hours later. The oxygenation index and alveolar-arterial oxygen difference P(A-a)O2, however, did not change markedly. Four (12%) patients needed further extracorporeal life support and two of these survived. The overall survival rate was 45.5%. Patients with heavier body weight (p less than 0.05) and of the male gender (p less than 0.05) had a higher risk of mortality.

CONCLUSION

As a relatively late rescue therapy after failure of CMV, HFOV may improve PaCO2 and PaO2/FiO2 in children with respiratory failure. However, it carries an increased mortality rate in patients with heavier body weight and male gender.