High-frequency oscillatory ventilation for adult acute respiratory distress syndrome: a decade of progress.
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High-Frequency Ventilation↗
Biomedical subjects
Stephen Derdak
Publications and source records attributed to Stephen Derdak.
High-frequency oscillatory ventilation in adults: respiratory therapy issues.
OBJECTIVE: To summarize clinical information and assessment techniques relevant to respiratory therapists caring for adult patients on high-frequency oscillatory ventilation (HFOV). DATA SOURCE: Review of observational studies, controlled trials, case reports, institutional experience, and hospital HFOV guidelines for adult patients. DATA SUMMARY: Respiratory therapists require unique physical assessment skills and knowledge in managing patients on HFOV. Respiratory therapy procedures relevant to HFOV include setting endotracheal tube cuff leaks, performing lung recruiting maneuvers, endotracheal suctioning, and monitoring ventilator parameters. Respiratory therapists serve as essential team members in the creation and implementation of written HFOV guidelines (e.g., algorithms) to optimize patient care. CONCLUSION: Respiratory therapy assessment and procedural skills are essential in providing optimal care to adult patients on HFOV.
High-Frequency Ventilation↗
High-frequency oscillatory ventilation: lessons learned from mechanical test lung models.
OBJECTIVE: Review data obtained from high-frequency oscillatory ventilation (HFOV) and mechanical test lung models with respect to delivered tidal volume, distal pressure transmission, endotracheal tube cuff leaks, and simulated clinical conditions. DESIGN: Review of selected studies from PubMed, published abstracts, and institutional mechanical test lung data. RESULTS: Tidal volume delivery during HFOV is altered by oscillatory pressure amplitude (DeltaP), frequency (Hz), percent inspiratory time (IT%), and patient variables. Distal (carinal) oscillatory pressure amplitude transmission is directly correlated with endotracheal tube diameter and peripheral airway resistance. Endotracheal tube cuff leaks promote egress of tracheal gas while attenuating distal oscillatory pressure amplitude and tidal volume transmission. Simulated clinical conditions (e.g., increased distal airway resistance, mainstem intubation) may increase observed DeltaP, whereas mean airway pressure is decreased with air leaks. CONCLUSION: Mechanical test lung and artificial trachea simulations may provide useful information on the interaction of HFOV with altered lung mechanics and may contribute to the formulation of HFOV clinical strategies. Important limitations of these models include absence of gas exchange, histologic and biologic markers, or hemodynamic data.
High-Frequency Ventilation↗
Acute respiratory distress syndrome in pregnancy.
OBJECTIVE: To summarize the pathophysiology and treatment of acute lung injury and acute respiratory distress syndrome (ARDS) during pregnancy. DATA SOURCE: Review of select articles from MEDLINE, including published abstracts, case reports, observational studies, controlled trials, review articles, and institutional experience. DATA SUMMARY: ARDS occurs in pregnancy and may have unique causes. Despite extensive clinical research to improve the management of ARDS, mortality remains high, and few strategies have shown a mortality benefit. Furthermore, in most published studies, pregnancy is an exclusionary criterion, and thus, few treatments have been adequately evaluated in obstetric populations. The treatment of ARDS in pregnancy is extrapolated from studies performed in the general ARDS patient population, with consideration given to the normal physiologic changes of pregnancy. In general, the best support of the fetus is support of the mother. From the age of viability (24-26 wks at most institutions) until full term, decisions regarding delivery should be made based primarily on the standard obstetric indications. CONCLUSIONS: Little evidence exists regarding the management of ARDS specifically in pregnancy, and thus, treatment approaches must be drawn from studies performed in a general patient population. A multidisciplinary approach involving maternal-fetal medicine, neonatology, anesthesiology, and intensivist clinicians is essential to optimizing maternal and fetal outcomes.
Critical Care↗
Images in clinical medicine. Buffalo chest.
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Humans↗
High-frequency oscillatory ventilation for acute respiratory distress syndrome in adult patients.
INTRODUCTION: High-frequency oscillatory ventilation (HFOV) using an open-lung strategy has been demonstrated to improve oxygenation in neonatal and pediatric respiratory failure, without increasing barotrauma. Animal studies using small (<4 mm) endotracheal tubes have shown reduced histopathologic evidence of lung injury and inflammatory mediator release, suggesting reduced ventilator-induced lung injury. CLINICAL STUDIES: During the last decade, case reports and observational studies of HFOV in patients failing conventional ventilation strategies have suggested improved oxygenation in adult patients with severe acute respiratory distress syndrome. These reports have also suggested that early (2 days) initiation of HFOV is more likely to result in survival than delayed initiation (>7 days). A recently published randomized, controlled trial in acute respiratory distress syndrome patients (n = 148) comparing HFOV with a pressure-control ventilation strategy (Pao(2)/Fio(2) ratio of 10 cm H(2)O) demonstrated early (<16 hrs) improvement in Pao(2)/Fio(2) (p =.008) in the HFOV group but no significant difference in oxygenation index between the two groups during the initial 72 hrs of treatment. Thirty-day mortality was 37% in the HFOV group and 52% in the conventional ventilation group (p =.102). There was no significant difference between treatment groups in the prevalence of barotrauma, hemodynamic instability, or mucus plugging. This study suggests that HFOV is as effective and safe as the conventional strategy to which it was compared. CLINICAL APPLICATION: For clinical use in adults, a trial of HFOV may be considered when Fio(2) requirements exceed 60% and mean airway pressure is approaching 20 cm H(2)O or higher (or, alternatively, positive end-expiratory pressure of >15 cm H(2)O). It is currently unknown whether initiating HFOV at a lower severity threshold would result in reduced ventilator-associated lung injury or mortality. FUTURE DIRECTIONS: Future studies should compare different algorithms of applying HFOV to determine the optimal techniques for achieving oxygenation and ventilation, while minimizing ventilator-associated lung injury. The potential role of adjunctive therapies used with HFOV (e.g., prone ventilation, inhaled nitric oxide, aerosolized vasodilators, liquid ventilation) will require further research.
Adult↗
High-frequency oscillatory ventilation for acute respiratory distress syndrome in adults: a randomized, controlled trial.
Observational studies of high-frequency oscillatory ventilation in adults with the acute respiratory distress syndrome have demonstrated improvements in oxygenation. We designed a multicenter, randomized, controlled trial comparing the safety and effectiveness of high-frequency oscillatory ventilation with conventional ventilation in adults with acute respiratory distress syndrome; 148 adults with acute respiratory distress syndrome (Pa(O2)/fraction of inspired oxygen <or= 200 mm Hg on 10 or more cm H2O positive end-expiratory pressure) were randomized to high-frequency oscillatory ventilation (n = 75) or conventional ventilation (n = 73). Applied mean airway pressure was significantly higher in the high-frequency oscillation group compared with the conventional ventilation group throughout the first 72 hours (p = 0.0001). The high-frequency oscillation group showed early (less than 16 hours) improvement in Pa(O2)/fraction of inspired oxygen compared with the conventional ventilation group (p = 0.008); however, this difference did not persist beyond 24 hours. Oxygenation index decreased similarly over the first 72 hours in both groups. Thirty-day mortality was 37% in the high-frequency oscillation group and was 52% in the conventional ventilation group (p = 0.102). The percentage of patients alive without mechanical ventilation at Day 30 was 36% and 31% in the high-frequency oscillation and conventional ventilation groups, respectively (p = 0.686). There were no significant differences in hemodynamic variables, oxygenation failure, ventilation failure, barotraumas, or mucus plugging between treatment groups. We conclude that high-frequency oscillation is a safe and effective mode of ventilation for the treatment of acute respiratory distress syndrome in adults.
APACHE↗
Minimally invasive hemodynamic monitoring for the intensivist: current and emerging technology.
OBJECTIVE: To review minimally invasive cardiac output monitoring devices currently available for use in the intensive care unit. DATA SOURCES: Medline search from 1966 to present plus cited reference studies and abstracts from available product literature. STUDY SELECTION: Selection criteria included published reports and abstracts comparing the accuracy of minimally invasive cardiac output monitors to a "gold standard." DATA SYNTHESIS: Many reports have been published on the accuracy of individual minimally invasive cardiac output monitors, but cumulative data reviewing each type of monitor have not been synthesized and made available to the clinician. CONCLUSIONS: Emerging noninvasive or minimally invasive means of cardiac output monitoring are based on varied physiologic principles and can be used for following hemodynamic trends. Each of these methods has advantages and disadvantages; it is important for the clinician to understand the strengths and limitations of each device to effectively use the information derived.
Cardiac Output↗