Risk Factors for the Mortality of Pneumocystis jirovecii Pneumonia in Non-HIV Patients Who Required Mechanical Ventilation: A Retrospective Case Series Study.

BACKGROUND: The risk factors for the mortality rate of Pneumocystis jirovecii pneumonia (PCP) who required mechanical ventilation (MV) remained unknown. METHODS: A retrospective chart review was performed of all PCP patients admitted to our intensive care unit and treated for acute hypoxemic respiratory failure to assess the risk factors for the high mortality. RESULTS: Twenty patients without human immunodeficiency virus infection required mechanical ventilation; 19 received noninvasive ventilation; and 11 were intubated. PEEP was incrementally increased and titrated to maintain FIO2 as low as possible. No mandatory ventilation was used. Sixteen patients (80%) survived. Pneumothorax developed in one patient with rheumatoid arthritis (RA). Median PEEP level in the first 5 days was 10.0 cmH2O and not associated with death. Multivariate analysis showed the association of incidence of interstitial lung disease and increase in serum KL-6 with 90-day mortality. CONCLUSIONS: We found MV strategies to prevent pneumothorax including liberal use of noninvasive ventilation, and PEEP titration and disuse of mandatory ventilation may improve mortality in this setting. Underlying disease of interstitial lung disease was a risk factor and KL-6 may be a useful predictor associated with mortality in patients with RA. These findings will need to be validated in larger studies.

Pressure-controlled inverse ratio ventilation as a rescue therapy for severe acute respiratory distress syndrome.

PURPOSE: Low tidal volume ventilation improves the outcomes of acute respiratory distress syndrome (ARDS). However, no studies have investigated the use of a rescue therapy involving mechanical ventilation when low tidal volume ventilation cannot maintain homeostasis. Inverse ratio ventilation (IRV) is one candidate for such rescue therapy, but the roles and effects of IRV as a rescue therapy remain unknown. METHODS: We undertook a retrospective review of the medical records of patients with ARDS who received IRV in our hospital from January 2007 to May 2014. Gas exchange, ventilation, and outcome data were collected and analyzed. RESULTS: Pressure-controlled IRV was used for 13 patients during the study period. Volume-controlled IRV was not used. IRV was initiated on 4.4 ventilation days when gas exchange could not be maintained. IRV significantly improved the PaO2/FiO2 from 76 ± 27 to 208 ± 91 mmHg without circulatory impairment. The mean duration of IRV was 10.5 days, and all survivors were weaned from mechanical ventilation and discharged. The 90-day mortality rate was 38.5 %. Univariate analysis showed that the duration of IRV was associated with the 90-day mortality rate. No patients were diagnosed with pneumothorax. CONCLUSIONS: Pressure-controlled IRV provided acceptable gas exchange without apparent complications and served as a successful bridge to conventional treatment when used as a rescue therapy for moderate to severe ARDS.

Roles of neurally adjusted ventilatory assist in improving gas exchange in a severe acute respiratory distress syndrome patient after weaning from extracorporeal membrane oxygenation: a case report.

BACKGROUND: Patient-ventilator asynchrony is a major cause of difficult weaning from mechanical ventilation. Neurally adjusted ventilatory assist (NAVA) is reported useful to improve the synchrony in patients with sustained low lung compliance. However, the role of NAVA has not been fully investigated. CASE PRESENTATION: The patient was a 63-year-old Japanese man with acute respiratory distress syndrome secondary to respiratory infection. He was treated with extracorporeal membrane oxygenation for 7 days and survived. Dynamic compliance at withdrawal of extracorporeal membrane oxygenation decreased to 20 ml/cmH2O or less, but gas exchange was maintained by full support with assist/control mode. However, weaning from mechanical ventilation using a flow trigger failed repeatedly because of patient-ventilator asynchrony with hypercapnic acidosis during partial ventilator support despite using different types of ventilators and different trigger levels. Weaning using NAVA restored the regular respiration and stable and normal acid-base balance. Electromyographic analysis of the diaphragm clearly showed improved triggering of both the start and the end of spontaneous inspiration. Regional ventilation monitoring using electrical impedance tomography showed an increase in tidal volume and a ventilation shift to the dorsal regions during NAVA, indicating that NAVA could deliver gas flow to the dorsal regions to adjust for the magnitude of diaphragmatic excursion. NAVA was applied for 31 days, followed by partial ventilatory support with a conventional flow trigger. The patient was discharged from the intensive care unit on day 110 and has recovered enough to be able to live without a ventilatory support for 5 h per day. CONCLUSION: Our experience showed that NAVA improved not only patient-ventilator synchrony but also regional ventilation distribution in an acute respiratory distress patient with sustained low lung compliance.

Safety and efficacy of bronchoalveolar lavage using a laryngeal mask airway in cases of acute hypoxaemic respiratory failure with diffuse lung infiltrates.

Objective Fibre-optic bronchoscopy with bronchoalveolar lavage (FOB-BAL) is an important tool for diagnosing and selecting treatment for acutely hypoxaemic patients with diffuse lung infiltrates. However, FOB-BAL carries a risk of significant hypoxaemia and subsequent tracheal intubation during and after the procedure. The application of FOB-BAL using a laryngeal mask airway (LMA) in combination with continuous positive airway pressure (CPAP) may minimize the incidence of hypoxaemia; however, the safety and efficacy of this procedure have not been investigated. Methods A retrospective chart review was performed from April to September 2013. Data regarding the recovered volume of BAL fluid, incidence of tracheal intubation within eight hours after the completion of FOB-BAL, respiratory and haemodynamic parameters and treatment modifications were collected for the evaluation. Results Ten trials of FOB-BAL using an LMA and CPAP were performed in nine patients with severe acute hypoxaemia associated with diffuse lung infiltrates. The BAL fluid recovery rate was 56%, and the procedure was completed without subsequent complications. In addition, the percutaneous arterial oxygen saturation decreased to 95.7%±3.8%, although it was never lower than 90.0% during the procedure, and no patients required intubation. Furthermore, the arterial blood pressure significantly but transiently decreased due to sedation, and the procedure yielded diagnostic information in all nine patients. Conclusion FOB-BAL using LMA and CPAP appears to be safe and effective in patients who develop severe acute hypoxaemia.

[Anesthetic management of a patient with Swyer-James syndrome].

Swyer-James syndrome (SJS) shows the constellation of radiographic findings of a small, hyper lucent lung, with an ipsilateral, diminished peripheral vasculature, air trapping, and a lack of peripheral fill on bronchography. We report a case of 70-year-old woman with SJS who underwent pulmonary resection of the normal side lung for lung tumor. Because of this syndrome, we could predict the hypoxia during one-lung ventilation. In fact, about ten minutes after beginning of one-lung ventilation, Sp(O2) decreased from 100% to 90%. As we could not improve the hypoxia in spite of increasing FI(O2), O2 administration to the operating side lung was started. Sp(O2) recovered after O2 administration. For anesthetic management of a patient with SJS in the normal-side-lung, it is essential to prevent the hypoxia during one-lung ventilation.

Phosphatidylcholine vesicle-mediated decomposition of hydrogen peroxide.

The decomposition of hydrogen peroxide (H2O2) was examined in aqueous solution (50 mM Tris-HCl buffer, pH 7.4, containing 100 mM NaCl) at 25 degrees C in pure buffer or in the presence of either vesicles or micelles formed from various phosphatidylcholines (PCs). In the absence of PCs, more than 90% of the initially added H2O2 (1.0 mM) remained intact after incubation for 120 h. The effect of the PCs on the decomposition of H2O2 was studied by using different PCs that varied in terms of number of carbon atoms in the two acyl chains n as well as in terms of the degree of unsaturation. PCs with short hydrocarbon chains (n = 4, 6-8) were dissolved in the buffer solution in the form of nonassociated monomers or as micelles in equilibrium with monomers at a fixed PC concentration of 10 mM. The presence of these short-chain PCs slightly enhanced the H2O2 decomposition rate. Micelles formed by non-lipid detergents (sodium cholate, Triton X-100, and sodium dodecylsulfate) had a similar effect. In marked contrast, PCs with long hydrocarbon chains (n > or = 10) dispersed in buffer solution as vesicles (liposomes) significantly enhanced the rate of H2O2 decomposition, with the most effective PC being 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) at 25 degrees C. This indicates that the packing density of the PC molecules influences the reactivity, presumably through the direct interaction of the PC assemblies with H2O2 molecules. Furthermore, in the case of vesicles formed from PCs with unsaturated acyl chains (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, POPC; 1,2-dioleoyl-sn-glycero-3-phosphocholine, DOPC), carbon-carbon double bond oxidation did not occur extensively under the conditions used. This indicates that the observed effect of PCs on the decomposition of H2O2 is indeed related to the assembly structure (vesicle vs micelles vs monomers) and is clearly not related to the presence of unsaturated hydrocarbon chains. Fluorescence polarization measurements of two fluorescent probes embedded either in the acyl chain region of the vesicles (DPH, 1,6-diphenyl-1,3,5-hexatriene) or on the surface of the vesicles (TMA-DPH, 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene iodide) show that the presence of H2O2 leads to a decrease in the fluidity of the lipid-water surface and not to a change in the fluidity of the hydrophobic region of the vesicle bilayer. This indicates that the decomposition of H2O2 is triggered through interactions between H2O2 and the polar head group area of PC vesicles.

Glucose oxidation catalyzed by liposomal glucose oxidase in the presence of catalase-containing liposomes.

A catalase-containing liposome (CAL) was prepared and characterized in terms of stability during storage and catalysis of the decomposition of hydrogen peroxide (H2O2) that was initially added or produced in the oxidation of glucose catalyzed by the glucose oxidase-containing liposomes (GOL). The reactors used were a test tube and an external loop airlift bubble column as the static liquid and circulating liquid flow systems, respectively. The free catalase (CA) at low concentrations was unstable during storage at 4 degrees C as a result of dissociation of the tetrameric CA subunits. On the other hand, the deactivation of the CA activity in the CAL was depressed because of the high CA concentration in the CAL liposome. The CAL effectively catalyzed the repeated decompositions at 25 degrees C with 10 mM H2O2 added initially, whereas the free CA was significantly deactivated during the repeated reactions. The high stability of the CAL was attributed to the moderately depressed reactivity, which was essentially derived from the diffusion limitation of the CAL membrane to H2O2 in the liquid bulk. In the GOL-catalyzed prolonged oxidation of 10 mM glucose at 40 degrees C in the static liquid in a test tube, both the free CA and CAL could continuously catalyze the decomposition of H2O2 produced. This was because the glucose oxidation rate was small due to the limited reactivity of the GOL to glucose with its low permeability through the GOL membrane. In the glucose oxidation catalyzed by the GOL with the free CA or the CAL in the airlift, much larger oxidation rates were observed compared to those in the test tube because the permeability of the GOL membrane to glucose was increased in the gas-liquid two phase flow in the airlift. The GOL/CAL system in the airlift operated in an acidic condition, which was preferable to the GO activity, gave the largest oxidation rate with negligible accumulation of the H2O2 produced. On the other hand, the GOL/free CA system gave an oxidation rate smaller than that of the GOL/CAL system even under the acidic condition due to an unfavorable interaction of the free CA molecules with the GOL membranes leading to the decreased reactivity of the GOL.

Mechanism for high stability of liposomal glucose oxidase to inhibitor hydrogen peroxide produced in prolonged glucose oxidation.

Glucose oxidase (GO) was encapsulated in the liposomes composed of POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) to increase the enzyme stability through its decreased inhibition because of hydrogen peroxide (H(2)O(2)) produced in the glucose oxidation. The GO-containing liposomes (GOLs) were completely free of the inhibition even in the complete conversion of 10 mM glucose at 25 degrees C because the H(2)O(2) concentration was kept negligibly low both outside and inside liposomes throughout the reaction. It was interestingly revealed that the H(2)O(2) produced was decomposed not only by a slight amount of catalase originally contained in the commercially available GO but also by the lipid membranes of GOL. As compared to the GOL-catalyzed reaction, the free GO-catalyzed reaction more highly accumulated H(2)O(2) because of the more rapid glucose conversion despite containing free catalase, leading to the completely inhibited GO before reaching a sufficient glucose conversion. This suggested that only the liposomal catalase could continue to catalyze the H(2)O(2) decomposition. The effect of the glucose oxidation rate, i.e., the H(2)O(2) production rate on the liposomal GO inhibition, was also examined employing the various GOLs with different permeabilities to glucose present in their external phase. It was concluded that the liposomal GO free of the inhibition could be obtained when the GOL-catalyzed H(2)O(2) formation rate was limited by such a suitable lipid bilayer as POPC membrane so that the rate was well-balanced with the sum of the above two H(2)O(2) decomposition rates. The highly stable GOL obtained in the present paper was shown to be a useful biocatalyst for the prolonged glucose oxidation.