Satoshi Yamaga

Tracheal intubation of a difficult airway using Airway Scope, Airtraq, and Macintosh laryngoscope: a comparative manikin study of inexperienced personnel.

BACKGROUND:The Airway Scope (AWS) (Pentax-AWS®, Hoya Corp., Tokyo, Japan) and the Airtraq® (ATQ) (Prodol, Vizcaya, Spain) have similarities in the novel structures of their blades. In this study, we evaluated the ease of use of the AWS and ATQ compared with the Macintosh laryngoscope (ML) by inexperienced personnel in a simulated manikin difficult airway. METHODS:Twenty-four fifth-year medical students with no previous experience in tracheal intubation participated in this study. We used an advanced patient simulator (SimMan®, Laerdal Medical, Stavanger, Norway) to simulate difficult airway scenarios including cervical spine rigidity, limited mouth opening, and pharyngeal obstruction. The sequences in selecting devices and scenarios were randomized. Success rates for tracheal intubation, and the time required for visualization of the glottis, tracheal intubation, and inflation of the lungs, and the number of optimization maneuvers and dental click sounds were analyzed. The 3 different intubation devices were tested in 4 different scenarios by 24 students. RESULTS:Both the AWS and ATQ had very high success rates of tracheal intubation compared with the ML (AWS 100%*; ATQ 98%*; and ML 89%; *P < 0.05 AWS, ATQ versus ML). The time to intubation with the AWS was significantly shorter than with the ATQ and ML (AWS 11 ± 6 seconds; ATQ 16 ± 12 seconds; and ML 16 ± 11 seconds; *P < 0.05 AWS versus ATQ, ML). The number of optimization maneuvers with the AWS was significantly lower than with the ATQ and ML. There were significantly more audible dental click sounds with the ML than with the AWS and ATQ. CONCLUSION:Both the AWS and ATQ may be suitable devices for difficult intubation by inexperienced personnel in this manikin simulated scenario. Further studies in a clinical setting are necessary to confirm these findings.

Is transpulmonary pressure-guided PEEP titration really optimal?

Dear Editor, In a recent issue of Intensive Care Medicine, we read with interest the article by Baedorf Kassis and colleagues [1], who investigated the utility of positive end-expiratory pressure (PEEP) titration according to transpulmonary pressure via esophageal manometry in acute respiratory distress syndrome (ARDS). The authors analyzed 56 of the original 61 patients enrolled in the EPVent study [2] and demonstrated that transpulmonary pressure-guided PEEP titration improved elastance and transpulmonary driving pressures were possibly associated with an improved 28-day mortality. We appreciate their results, which may lead to a change in our daily practice. However, several factors potentially affecting the current results should be addressed. First, it remains uncertain whether the PEEP levels at higher levels or titrated according to the transpulmonary driving pressure were really optimal. Briel et al. demonstrated in their systematic review and meta-analysis that higher levels of PEEP were associated with improved survival in patients with moderate to severe ARDS with partial pressure arterial oxygen/fraction of inspired oxygen (PaO2/FIO2) ratio <200 [3]. The applied FIO2 and PEEP on day 1 were 0.51 and 15.3 cmH2O in the higher PEEP group and 0.61 and 9.0 cmH2O in the lower PEEP group, respectively. However, the applied PEEP in the control group of the current study was determined according to the ARDSnet table [4], which was similar to the lower PEEP group reported by Briel, suggesting that the setting of PEEP in the control group of the current study, in which mean PaO2/FIO2 ratio was 142, was too low. The comparison of the transpulmonary pressure-guided strategy with the higher PEEP strategy [3] would be suggested. Second, the authors showed a potential association between decreased driving pressure at 24 h and the improved 28-day mortality. However, therapeutic regimens including corticosteroids, antibiotics, and fluid management, which can potentially affect 28-day mortality, were not assessed in this study. In particular, the presence or absence of spontaneous breathing could have largely affected the PEEP titration according to the transpulmonary pressure guidance [5]. Therefore, information on the use of sedative agents and/or neuromuscular blockers is important for the precise evaluation of the transpulmonary pressure-guided PEEP titration. In addition, data describing patients’ conditions and therapeutic regimens between 24 h and 28 days from enrollment would be helpful. In summary, we applaud the current results provided by Baedorf Kassis and colleagues. However, we suggest that the authors provide additional data for better understanding of the potential benefit of transpulmonary pressure-guided PEEP titration in ARDS.

Sera from Septic Patients Contain the Inhibiting Activity of the Extracellular ATP-Dependent Inflammasome Pathway

Immunoparalysis is a common cause of death for critical care patients with sepsis, during which comprehensive suppression of innate and adaptive immunity plays a significant pathophysiological role. Although the underlying mechanisms are unknown, damage-associated molecular patterns (DAMPs) from septic tissues might be involved. Therefore, we surveyed sera from septic patients for factors that suppress the innate immune response to DAMPs, including adenosine triphosphate (ATP), monosodium urate, and high mobility group box-1. Macrophages, derived from THP-1 human acute monocytic leukemia cells, were incubated with each DAMP, in the presence or absence of sera that were collected from critically ill patients. Secreted cytokines were then quantified, and cell lysates were assayed for relevant intracellular signaling mediators. Sera from septic patients who ultimately did not survive significantly suppressed IL-1β production only in response to extracellular ATP. This effect was most pronounced with sera collected on day 3, and persisted with sera collected on day 7. However, this effect was not observed when THP-1 cells were treated with sera from survivors of sepsis. Septic sera collected at the time of admission (day 1) also diminished intracellular levels of inositol 1,4,5-triphosphate and cytosolic calcium (P < 0.01), both of which are essential for ATP signaling. Finally, activated caspase-1 was significantly diminished in cells exposed to sera collected on day 7 (P < 0.05). In conclusion, the sera of septic patients contain certain factors that persistently suppress the immune response to extracellular ATP, thereby leading to adverse clinical outcomes.

Regional Negative Pressure Pulmonary Edema with Pulmonary Thromboembolism

A 33-year-old woman with a body mass index of 43 presented with progressing severe dyspnea. Her oxygen saturation was 73% with room air, and contrast-enhanced computed tomography (CT) showed a deficit in the pulmonary artery (allow), suggesting pulmonary thromboembolism (Picture 1A) with regional ground-glass opacities in both lung fields (Picture 1B). Bronchoalveolar lavage fluid was serous, and no bacterial organisms were detected. High inspiratory effort during dyspneic breathing that occurs in obese patients with obstructed sleep apnea may have caused excess negative pressure in the alveoli, leading to pulmonary edema (1, 2). The blood-perfused lesions on lung scintigraphy (Picture 2A) were consistent with the ground-glass opacity lesions on three-dimensional reconstructed CT images of the lungs (Picture 2B), suggesting the negativepressure pulmonary edema was limited to the perfused le-

Confounders for interpreting the benefit of a biomarker-based strategy in early discontinuation of empirical antifungal therapy

Initial correspondence from Drs. Yamaga, Ohshimo and Shime We would like to discuss factors that potentially affect the results of a biomarker-based antifungal therapeutic algorithm in a recent issue of Intensive Care Medicine [1]. First, the Clinical Practice Guideline of the Infectious Diseases Society of America states that β-d-glucan testing is useful for excluding invasive candidiasis in the ICU setting, based on a meta-analysis presenting its high negative predictive value [2]. The authors’ algorithm, however, uses empirical antifungal therapy solely with positive anti-mannan testing, regardless of negative β-d-glucan tests, which could have resulted in overuse of antifungal therapy. Second, patients in the control group were treated until day 14, regardless of the results of serological biomarkers at days 0 and 4, which seemed to be inappropriately long as routine care. The aforementioned guideline recommends that empirical antifungal therapy should be discontinued in patients with no clinical response, no subsequent evidence of invasive candidiasis, or negative serological fungal biomarkers at 4–5 days [2]. Additionally, the long duration of antifungal therapy could have increased the cost, resulting in incorrect interpretation of the cost analysis. Third, fluconazole was the most frequently used (50%) initial antifungal therapy. This, however, is not concordant with the recommendation of the European Society of Clinical Microbiology and Infectious Diseases guidelines, in which echinocandins, but not fluconazole, are recommended for initial treatment of candidemia [3]. The reasons for the dissociation could be discussed. Finally, provision of adjunctive treatment including source control and central vascular catheter removal would be appreciated because they are also significant mortality risk factors in invasive Candida infection.

Risk factors for sepsis-associated encephalopathy

Initial correspondence from Drs. Yamaga and Shime Dear Editor, We would like to discuss factors potentially affecting the results of “modifiable factors for sepsis-associated encephalopathy (SAE)” [1]. First, the authors defined SAE solely by a Glasgow coma scale (GCS) less than 15 or features of delirium at admission to the intensive care unit using retrospectively collected data. The authors might fail to exclude several factors causing impaired conscious level, namely primary metabolic disturbances, such as hypoglycemia or hypernatremia [2], withdrawal of psychoactive drugs or alcohol, or Wernicke’s encephalopathy [3], in the assessment of SAE. This could have resulted in significantly higher numbers of SAE cases (1341/2513 = 53%), biasing analysis of risk factors. Second, the authors showed that 541 of 1341 (40%) SAE patients had GCS of 3–8 (Online resource 8), indicating that the cohort included more severe patients than a previous study, in which 26% patients of SAE had GCS 3–8 [2]. Given that 1230 (92%) patients with SAE had septic shock and 935 (70%) had severe hypoxemia, a considerable portion of deterioration in consciousness could be due to shock-induced cerebral hypoperfusion or hypoxemia, rather than encephalopathy. Third, a significant association between SAE and increased mortality seems only to demonstrate a relationship between the GCS and mortality, which is not surprising. The term “sepsis-associated encephalopathy” could be replaced by “sepsis-induced unconsciousness”. Finally, selection of parameters that were included in multivariate analysis was not well defined. Provision of the rationale for inclusion of microorganisms or infectious foci would be appreciated because these are theoretically unlikely to be significant risk factors for encephalopathy.