The use of high-frequency percussive ventilation after cardiac surgery significantly improves gas exchange without impairment of hemodynamics.

OBJECTIVE: Respiratory failure represents a significant source of morbidity and mortality for surgical patients. High-frequency percussive ventilation (HFPV) is emerging as a potentially effective rescue therapy in patients failing conventional mechanical ventilation (CMV). Use of HFPV is often limited by concerns for potential effects on hemodynamics, which is particularly tenuous in patients immediately after cardiac surgery. In this manuscript we evaluated the effects of HFPV on gas exchange and cardiac hemodynamics in the immediate postoperative period after cardiac surgery, in comparison with CMV. METHODS: Twenty-four consecutive cardiac surgery patients were ventilated in immediate postoperative period with HFPV for two to four hours, then they switched to a CMV using the adaptive support ventilation mode for weaning. Arterial blood gases were performed during the first and second hour on HFPV, and at 45 minutes after initiation of CMV. Respiratory settings and invasive hemodynamic data (mixed venous oxygen saturation, central venous pressure, systemic and pulmonary blood pressure, cardiac output and index) were collected utilizing right heart pulmonary catheter and arterial lines during HFPV and CMV. Primary outcome was improvement in the ratio between partial pressure of oxygen to fraction of inspired oxygen (P/F ratio) and changes in hemodynamics. RESULTS: Analysis of data for 24 patients revealed a significantly better P/F ratio during the first and second hour on HFPV, compared with a P/F ratio on CMV (420.0 ± 158.8, 459.2 ± 138.5, and 260.2 ± 98.5 respectively, p < 0.05), suggesting much better gas exchange on HFPV than on CMV. Hemodynamics were not affected by the mode of the ventilation. CONCLUSIONS: Improvement in gas exchange, reflected in a significantly improved P/F ratio, wasn't accompanied by worsening in hemodynamic parameters. The significant gains in the P/F ratio were lost when patients were switched to conventional ventilation. This data suggest that HFPV provides significantly better gas exchange compared with CMV and can be safely utilized in postoperative cardiac patients without any significant effect on hemodynamics.

Mechanical ventilatory support in potential lung donor patients.

Lung transplantation reduces mortality in patients with end-stage lung disease; however, only approximately 21% of lungs from potential donor patients undergo transplantation. A large number of donor lungs become categorized as unsuitable for lung transplantation as a result of lung injury around the time of brain death. Limiting this injury is key to increasing the number of successful lung procurements and subsequent transplants. This narrative review by a working group of pulmonologists, respiratory therapists, and lung transplant specialists elucidates principles of mechanical ventilatory support that can be used to limit lung injury in potential lung donor patients and examines the implementation of protocolized strategies in enhancing the procurement of donor lungs for transplantation.

Severe hypoxemic respiratory failure: part 2--nonventilatory strategies.

ARDS is characterized by hypoxemic respiratory failure, which can be refractory and life-threatening. Modifications to traditional mechanical ventilation and nontraditional modes of ventilation are discussed in Part 1 of this two-part series. In this second article, we examine nonventilatory strategies that can influence oxygenation, with particular emphasis on their role in rescue from severe hypoxemia. A literature search was conducted and a narrative review written to summarize the use of adjunctive, nonventilatory interventions intended to improve oxygenation in ARDS. Several adjunctive interventions have been demonstrated to rapidly ameliorate severe hypoxemia in many patients with severe ARDS and therefore may be suitable as rescue therapy for hypoxemia that is refractory to prior optimization of mechanical ventilation. These include neuromuscular blockade, inhaled vasoactive agents, prone positioning, and extracorporeal life support. Although these interventions have been linked to physiologic improvement, including relief from severe hypoxemia, and some are associated with outcome benefits, such as shorter duration of mechanical ventilation, demonstration of survival benefit has been rare in clinical trials. Furthermore, some of these nonventilatory interventions carry additional risks and/or high cost; thus, when used as rescue therapy for hypoxemia, it is important that they be demonstrated to yield clinically significant improvement in gas exchange, which should be periodically reassessed. Additionally, various management strategies can produce a more gradual improvement in oxygenation in ARDS, such as conservative fluid management, intravenous corticosteroids, and nutritional modification. Although improvement in oxygenation has been reported with such strategies, demonstration of additional beneficial outcomes, such as reduced duration of mechanical ventilation or ICU length of stay, or improved survival in randomized controlled trials, as well as consideration of potential adverse effects should guide decisions on their use. Various nonventilatory interventions can positively impact oxygenation as well as outcomes of ARDS. These interventions may be considered for use, particularly for cases of refractory severe hypoxemia, with proper appreciation of potential costs and adverse effects.

Severe hypoxemic respiratory failure: part 1--ventilatory strategies.

Approximately 16% of deaths in patients with ARDS results from refractory hypoxemia, which is the inability to achieve adequate arterial oxygenation despite high levels of inspired oxygen or the development of barotrauma. A number of ventilator-focused rescue therapies that can be used when conventional mechanical ventilation does not achieve a specific target level of oxygenation are discussed. A literature search was conducted and narrative review written to summarize the use of high levels of positive end-expiratory pressure, recruitment maneuvers, airway pressure-release ventilation, and high-frequency ventilation. Each therapy reviewed has been reported to improve oxygenation in patients with ARDS. However, none of them have been shown to improve survival when studied in heterogeneous populations of patients with ARDS. Moreover, none of the therapies has been reported to be superior to another for the goal of improving oxygenation. The goal of improving oxygenation must always be balanced against the risk of further lung injury. The optimal time to initiate rescue therapies, if needed, is within 96 h of the onset of ARDS, a time when alveolar recruitment potential is the greatest. A variety of ventilatory approaches are available to improve oxygenation in the setting of refractory hypoxemia and ARDS. Which, if any, of these approaches should be used is often determined by the availability of equipment and clinician bias.

Transthyretin as a marker to predict outcome in critically ill patients.

BACKGROUND: A determination of serum Transthyretin (TTR, Prealbumin) level is an objective method of assessing protein catabolic loss of severely ill patients and numerous studies have shown that TTR levels correlate with patient outcomes of non-critically ill patients. We evaluated whether TTR level correlates with the prevalence of PEM in the ICU and evaluated serum TTR level as an indicator of the effectiveness of nutrition support and the prognosis in critically ill patients. METHODS: We studied PEM prevalence in 118 patients admitted to a community hospital's medical intensive care unit and the association between TTR, low albumin (ALB) concentration and high-risk disease (HRD), i.e., sepsis, inability to take in oral nutrients, etc. Serum TTR was measured on the day of admission, day 3 and day 7 of their ICU stay. APACHE II and SOFA score was assessed on the day of admission and the nutritional status and nutritional requirement was assessed for their entire ICU stay. Patients were divided into three groups based on initial TTR level and the outcome analysis was performed for APACHE II score, SOFA score, ICU length of stay, hospital length of stay, and mortality. RESULTS: TTR showed excellent concordance with patients classified with PEM or at high malnutrition risk, and followed for 7 days, it is a measure of the metabolic burden. TTR levels decline from day 1 to day 7 in spite of providing nutritional support. Patients were classified in 3 categories with respect to the level of TTR: more than 170 mg/L, twenty-five patients (group 3); 100-170 mg/L, forty-eight patients (group 2); less than 100 mg/L, forty-five patients (group 1). TTR level correlated with ICU length of stay, hospital length of stay, and APACHE II score, and predicts mortality. CONCLUSIONS: TTR identified patients at highest risk for metabolic losses associated with stress hypermetabolism as serum TTR levels did not respond early to nutrition support because of the delayed return to anabolic status. It is particularly helpful in removing interpretation bias, and it is an excellent measure of the systemic inflammatory response concurrent with a preexisting state of chronic inanition.

Update on pleural diseases--2007.

BACKGROUND: New information is available on pleural diseases. The authors selected articles to make recommendations on diagnostic and treatment aspects of pleural diseases. MATERIALS AND METHODS: Eleven articles published in the English language between 2004 and 2007 were chosen. The basis of selection of the articles was the impact on daily practice, change in prior thinking of a disease process or specific treatment modality, as well as proper design and execution of the study. 5-Amino-laevulinic acid with fluorescent light combined with white light may allow further diagnostic yield in undiagnosed pleural disease. FDG-PET may allow prognostication of patients with pleural tumors. Utilizing ultrasound by trained Emergency Department physicians is a rapid and effective technique to evaluate non-traumatic pleural effusions in symptomatic patients. Serum osteopontin levels may distinguish patients exposed to asbestos with benign disease from those with pleural mesothelioma. Administration of streptokinase in patients with empyema does not need for surgical drainage, length of hospital stay, or mortality as compared to conventional treatment with chest tube drainage and intravenous antibiotics. Silver nitrate may be an alternative agent to talc for producing pleurodesis. Routine use of graded talc (50% particles greater than 25 microns) is recommended to reduce the morbidity associated with talc pleurodesis. Study design does not permit us to conclude that aspiration of spontaneous pneumothorax is as effective as chest tube drainage. Pleural catheter may prove to be an important palliative modality in treating debilitated patients or patients with trapped lung who show symptomatic improvement with drainage; however, at the present time, these catheters cannot be considered a first line treatment option for patients with malignant pleural effusion. One of the studies reviewed showed no significant difference in tract metastasis in patients with malignant mesothelioma undergoing an invasive pleural procedure with or without irradiation to the procedure site. However, the design of the trial does not allow us to make this conclusion at the present time.