ジンコウ コキュウ カンリ ト ハイ ソンショウ

Mechanical ventilation is essential to take care of critically ill patients, and it has been saving a lot of lives. On the other hand, it is apparent that mechanical ventilation promotes lung injury. NIH trial proved that low tidal volume ventilation to avoid ventilator-induced lung injury （VILI） improved the mortality of acute lung injury （ALI） and acute respiratory distress syndrome （ARDS）. When we take care of mechanically ventilated patients, we should be careful to minimize VILI. To achieve it, it is prudent to understand the mechanisms of VILI. In humans, the extent to which mechanical ventilation exacerbates antecedent lung injury in ALI/ARDS is hard to evaluate, and the lung injury related to mechanical ventilation is called ventilator-associated lung injury （VALI）. The clinical value of ventilatory strategy to avoid alveolar overdistension was demonstrated in NIH trial. Low tidal volume ventilation reduced mortality of ALI/ARDS by ２０ percent. The strength of this finding has changed practice, and low tidal volume ventilation has become the standard of care in ALI/ARDS. No doubt the benefit is related to a decrease in VALI. Many animal studies supported a variety of methods to minimize VILI. In ARDS widespread atelectasis is common, and shear forces are created to distend the adjacent lung units that remain open. A rabbit model demonstrated that cyclical atelectasis promoted VILI, and that PEEP prevented the development of VILI. The ideal level of PEEP in ARDS is not known. Body position also influenced the development of VILI in animal studies. Prone position was protective against VILI. High inspiratory flow also injured the lungs. Unfortunately these modalities have not been proved to be effective in humans. The mortality of ALI/ARDS decreased significantly in the last decade, it is still high. When we take care of mechanically ventilated patients, lung protective strategies are essential. We should search for safer ventilatory strategies to improve the mortality of ALI/ARDS

Change in Ratio of Observed-to-Expected Deaths in Pediatric Patients after Implementing a Closed Policy in an Adult ICU That Admits Children

Backgrounds. We examined the effect on the prognosis of critically ill pediatric patients after a closed ICU policy was implemented into an adult ICU that admitted children. Materials and Methods. We assessed the Pediatric Index of Mortality 2 (PIM2) score of pediatric patients (≤15 y.o.) admitted to the ICU from 2001 to 2009. In our teaching hospital, the department for intensive care was established in January 2004. Since then, for critical care patients, we have followed a closed ICU policy with full-time intensivists. We subsequently compared PIM2 scores and the ratio of observed-to-expected deaths (O/E ratio) for three three-year periods: 2001–2003 (before closed policy), 2004–2006, and 2007–2009. Results. Data was collected from 532 pediatric patients. While the PIM2 score statistically significantly increased from 0.066 ± 0.130 for 2001–2003 to 0.114 ± 0.239 for 2004–2006 and 0.086 ± 0.147 for 2007–2009, the O/E ratio decreased from 1.49 for 2001–2003 to 0.82 for 2004–2006 and remained at 0.82 for 2007–2009. Conclusion. The O/E ratio for critically ill pediatric patients improved after the establishment of a closed policy in an adult ICU that admitted children

Humidification Performance of Heat and Moisture Exchangers for Pediatric Use

Background. While heat and moisture exchangers (HMEs) have been increasingly used for humidification during mechanical ventilation, the efficacy of pediatric HMEs has not yet been fully evaluated. Methods. We tested ten pediatric HMEs when mechanically ventilating a model lung at respiratory rates of 20 and 30 breaths/min and pressure control of 10, 15, and 20 cmH2O. The expiratory gas passed through a heated humidifier. We created two rates of leakage: 3.2 L/min (small) and 5.1 L/min (large) when pressure was 10 cmH2O. We measured absolute humidity (AH) at the Y-piece. Results. Without leakage, eight of ten HMEs maintained AH at more than 30 mg/L. With the small leak, AH decreased below 30 mg/L (26.6 to 29.5 mg/L), decreasing further (19.7 to 27.3 mg/L) with the large leak. Respiratory rate and pressure control level did not affect AH values. Conclusions. Pediatric HMEs provide adequate humidification performance when leakage is absent

Upper limb muscle atrophy associated with in-hospital mortality and physical function impairments in mechanically ventilated critically ill adults : a two-center prospective observational study

Background: Lower limb muscle atrophy is often observed in critically ill patients. Although upper limb muscles can undergo atrophy, it remains unclear how this atrophy is associated with clinical outcomes. We hypothesized that this atrophy is associated with mortality and impairments in physical function. Methods: In this two-center prospective observational study, we included adult patients who were expected to require mechanical ventilation for > 48 h and remain in the intensive care unit (ICU) for > 5 days. We used ultrasound to evaluate the cross-sectional area of the biceps brachii on days 1, 3, 5, and 7 and upon ICU discharge along with assessment of physical functions. The primary outcome was the relationship between muscle atrophy ratio and in-hospital mortality on each measurement day, which was assessed using multivariate analysis. The secondary outcomes were the relationships between upper limb muscle atrophy and Medical Research Council (MRC) score, handgrip strength, ICU Mobility Scale (IMS) score, and Functional Status Score for the ICU (FSS-ICU). Results: Sixty-four patients (43 males; aged 70 ± 13 years) were enrolled. The Acute Physiology and Chronic Health Evaluation (APACHE) II score was 27 (22–30), and in-hospital mortality occurred in 21 (33%) patients. The decreased cross-sectional area of the biceps brachii was not associated with in-hospital mortality on day 3 (p = 0.43) but was associated on days 5 (p = 0.01) and 7 (p < 0.01), which was confirmed after adjusting for sex, age, and APACHE II score. In 27 patients in whom physical functions were assessed, the decrease of the cross-sectional area of the biceps brachii was associated with MRC score (r = 0.47, p = 0.01), handgrip strength (r = 0.50, p = 0.01), and FSS-ICU (r = 0.56, p < 0.01), but not with IMS score (r = 0.35, p = 0.07) upon ICU discharge. Conclusions: Upper limb muscle atrophy was associated with in-hospital mortality and physical function impairments; thus, it is prudent to monitor it

Does the tube-compensation function of two modern mechanical ventilators provide effective work of breathing relief?

OBJECTIVE: An endotracheal tube (ETT) imposes work of breathing on mechanically ventilated patients. Using a bellows-in-a-box model lung, we compared the tube compensation (TC) performances of the Nellcor Puritan-Bennett 840 ventilator and of the Dräger Evita 4 ventilator. MEASUREMENTS AND RESULTS: Each ventilator was connected to the model lung. The respiratory rate of the model lung was set at 10 breaths/min with 1 s inspiratory time. Inspiratory flows were 30 or 60 l/min. A full-length 8 mm bore ETT was inserted between the ventilator circuit and the model lung. The TC was set at 0%, 10%, 50%, and 100% for both ventilators. Pressure was monitored at the airway, the trachea, and the pleura, and the data were recorded on a computer for later analysis of the delay time, of the inspiratory trigger pressure, and of the pressure–time product (PTP). The delay time was calculated as the time between the start of inspiration and minimum airway pressure, and the inspiratory trigger pressure was defined as the most negative pressure level. The same measurements were performed under pressure support ventilation of 4 and 8 cmH(2)O. The PTP increased according to the magnitude of inspiratory flow. Even with 100% TC, neither ventilator could completely compensate for the PTP imposed by the ETT. At 0% TC the PTP tended to be less with the Nellcor Puritan-Bennett 840 ventilator, while at 100% TC the PTP tended to be less with the Dräger Evita 4 ventilator. A small amount of pressure support can be equally effective to reduce the inspiratory effort compared with the TC. CONCLUSION: Although both ventilators provided effective TC, even when set to 100% TC they could not entirely compensate for a ventilator and ETT-imposed work of breathing. The effect of TC is less than that of pressure support ventilation. Physicians should be aware of this when using TC in weaning trials

Change in diaphragm and intercostal muscle thickness in mechanically ventilated patients : a prospective observational ultrasonography study

Background: Diaphragm atrophy is observed in mechanically ventilated patients. However, the atrophy is not investigated in other respiratory muscles. Therefore, we conducted a two-center prospective observational study to evaluate changes in diaphragm and intercostal muscle thickness in mechanically ventilated patients. Methods: Consecutive adult patients who were expected to be mechanically ventilated longer than 48 h in the ICU were enrolled. Diaphragm and intercostal muscle thickness were measured on days 1, 3, 5, and 7 with ultrasonography. The primary outcome was the direction of change in muscle thickness, and the secondary outcomes were the relationship of changes in muscle thickness with patient characteristics. Results: Eighty patients (54 males and 26 females; mean age, 68 ± 14 years) were enrolled. Diaphragm muscle thickness decreased, increased, and remained unchanged in 50 (63%), 15 (19%), and 15 (19%) patients, respectively. Intercostal muscle thickness decreased, increased, and remained unchanged in 48 (60%), 15 (19%), and 17 (21%) patients, respectively. Decreased diaphragm or intercostal muscle thickness was associated with prolonged mechanical ventilation (median difference (MD), 3 days; 95% CI (confidence interval), 1–7 and MD, 3 days; 95% CI, 1–7, respectively) and length of ICU stay (MD, 3 days; 95% CI, 1–7 and MD, 3 days; 95% CI, 1–7, respectively) compared with the unchanged group. After adjusting for sex, age, and APACHE II score, they were still associated with prolonged mechanical ventilation (hazard ratio (HR), 4.19; 95% CI, 2.14–7.93 and HR, 2.87; 95% CI, 1.53–5.21, respectively) and length of ICU stay (HR, 3.44; 95% CI, 1.77–6.45 and HR, 2.58; 95% CI, 1.39–4.63, respectively) compared with the unchanged group. Conclusions: Decreased diaphragm and intercostal muscle thickness were frequently seen in patients under mechanical ventilation. They were associated with prolonged mechanical ventilation and length of ICU stay

Effects of reduced rebreathing time, in spontaneously breathing patients, on respiratory effort and accuracy in cardiac output measurement when using a partial carbon dioxide rebreathing technique: a prospective observational study

INTRODUCTION: New technology using partial carbon dioxide rebreathing has been developed to measure cardiac output. Because rebreathing increases respiratory effort, we investigated whether a newly developed system with 35 s rebreathing causes a lesser increase in respiratory effort under partial ventilatory support than does the conventional system with 50 s rebreathing. We also investigated whether the shorter rebreathing period affects the accuracy of cardiac output measurement. METHOD: Once a total of 13 consecutive post-cardiac-surgery patients had recovered spontaneous breathing under pressure support ventilation, we applied a partial carbon dioxide rebreathing technique with rebreathing of 35 s and 50 s in a random order. We measured minute ventilation, and arterial and mixed venous carbon dioxide tension at the end of the normal breathing period and at the end of the rebreathing periods. We then measured cardiac output using the partial carbon dioxide rebreathing technique with the two rebreathing periods and using thermodilution. RESULTS: With both rebreathing systems, minute ventilation increased during rebreathing, as did arterial and mixed venous carbon dioxide tensions. The increases in minute ventilation and arterial carbon dioxide tension were less with 35 s rebreathing than with 50 s rebreathing. The cardiac output measures with both systems correlated acceptably with values obtained with thermodilution. CONCLUSION: When patients breathe spontaneously the partial carbon dioxide rebreathing technique increases minute ventilation and arterial carbon dioxide tension, but the effect is less with a shorter rebreathing period. The 35 s rebreathing period yielded cardiac output measurements similar in accuracy to those with 50 s rebreathing