Year in review in Intensive Care Medicine 2012: III. Noninvasive ventilation, monitoring and patient-ventilator interactions, acute respiratory distress syndrome, sedation, paediatrics and miscellanea

Activation of death-associated protein kinase 1 promotes neutrophil apoptosis to accelerate inflammatory resolution in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a uniform progression of overwhelming inflammation in lung tissue with extensive infiltration of inflammatory cells. Neutrophil apoptosis is thought to be a significant process in the control of the resolution phase of inflammation. It has been proved that 5-Aza-2'-deoxycytidine (Aza) can inhibit cancer by activating death-associated protein kinase 1 (DAPK1) to promote apoptosis. However, the effect of DAPK1 on neutrophil apoptosis is unclear, and research on the role of Aza in inflammation is lacking. Here, we investigated whether Aza can regulate DAPK1 expression to influence the fate of neutrophils in ARDS. In vitro, we stimulated neutrophil-like HL-60 (dHL-60) cells with different concentrations of Aza for different durations and used RNA interference to up- or downregulate DAPK1 expression. We observed that culturing dHL-60 cells with Aza increased apoptosis by inhibiting NF-κB activation to modulate the expression of Bcl-2 family proteins, which was closely related to the levels of DAPK1. In vivo, ARDS was evoked by intratracheal instillation of lipopolysaccharide (LPS; 3 mg/kg). One hour after LPS administration, mice were treated with Aza (1 mg/kg, i.p.). To inhibit DAPK1 expression, mice were intraperitoneally injected with a DAPK1 inhibitor. Aza treatment accelerated inflammatory resolution in LPS-induced ARDS by suppressing pulmonary edema, alleviating lung injury and decreasing the infiltration of inflammatory cells in bronchoalveolar lavage fluid (BALF). Moreover, Aza reduced the production of proinflammatory cytokines. However, administration of the DAPK1 inhibitor attenuated the protective effects of Aza. Similarly, the proapoptotic function of Aza was prevented when DAPK1 was inhibited either in vivo or in vitro. In summary, Aza promotes neutrophil apoptosis by activating DAPK1 to accelerate inflammatory resolution in LPS-induced ARDS. This study provides the first evidence that Aza prevents LPS-induced neutrophil survival by modulating DAPK1 expression.

Simulated internal jugular vein cannulation using a needle-guiding device

BACKGROUND

Using a two-dimensional ultrasound-guided approach does not guarantee success during the first attempt at internal jugular vein cannulation. Our randomized, parallel simulation study examined whether a new disposable device could improve the success rate of the first attempt at ultrasound-guided internal jugular vein cannulation of a simulated internal jugular vein.

METHODS

Eighty-eight participants were randomized to perform needle insertion for internal jugular vein cannulation of a phantom using the ultrasound-guided approach with (case group) or without (control group) this new device. The primary outcome was the success rate of the first attempt. The secondary outcome was the frequency of mechanical complications such as arterial puncture and posterior wall puncture, procedure time, and level of difficulty.

RESULTS

Among 44 participants using the device, 33 (75.0%) achieved successful cannulation on the first attempt. However, only 12 (27.3%) of the 44 participants not using the device recorded success during the first attempt (risk difference, 0.477; 95% confidence interval [CI] 0.294-0.661; P<0.001). The number of attempts was significantly lower (risk difference, -3.955; 95% CI, -5.014 to -3.712; P<0.001) when participants performed cannulation with the device (1.63±1.71) than without the device (5.59±5.78). Our study also showed that participants were comfortable when performing the ultrasound-guided approach with the new device (risk difference, -1.955; 95% CI, -2.016 to -1.493; P<0.0001).

CONCLUSIONS

The new disposable device was effective for successful first attempts at needle insertion during ultrasound-guided internal jugular vein cannulation. Future clinical trials are needed to assess the effectiveness of this device.

Domiciliary noninvasive positive airway pressure therapy in children

There has been a dramatic increase in the past few decades in the number of children receiving noninvasive positive airway pressure (PAP) therapy at home. Although PAP therapy was first prescribed for children with obstructive sleep apnea, the indications have rapidly widened to include treatment for central hypoventilation syndromes, neuromuscular and chest wall disorders as well as primary respiratory diseases. Given the rapidly expanding use of PAP therapy in children, pediatric pulmonologists need to be familiar with the indications, technical and safety considerations as well as potential complications and challenges that may arise when caring for children using PAP therapy. This review article covers the definition of PAP therapy, modes, interfaces, devices, indications, contraindications, suggested settings, complications as well as the factors influencing the adherence.

Development and validation of the pediatric risk estimate score for children using extracorporeal respiratory support (Ped-RESCUERS)

PURPOSE

To develop and validate the Pediatric Risk Estimation Score for Children Using Extracorporeal Respiratory Support (Ped-RESCUERS). Ped-RESCUERS is designed to estimate the in-hospital mortality risk for children prior to receiving respiratory extracorporeal membrane oxygenation (ECMO) support.

METHODS

This study used data from an international registry of patients aged 29 days to less than 18 years who received ECMO support from 2009 to 2014. We divided the registry into development and validation datasets by calendar date. Candidate variables were selected for model inclusion if the variable independently changed the mortality risk by at least 2 % in a Bayesian logistic regression model with in-hospital mortality as the outcome. We characterized the model's ability to discriminate mortality with the area under curve (AUC) of the receiver operating characteristic.

RESULTS

From 2009 to 2014, 2458 non-neonatal children received ECMO for respiratory support, with a mortality rate of 39.8 %. The development dataset contained 1611 children receiving ECMO support from 2009 to 2012. The model included the following variables: pre-ECMO pH, pre-ECMO arterial partial pressure of carbon dioxide, hours of intubation prior to ECMO support, hours of admission at ECMO center prior to ECMO support, ventilator type, mean airway pressure, pre-ECMO use of milrinone, and a diagnosis of pertussis, asthma, bronchiolitis, or malignancy. The validation dataset included 438 children receiving ECMO support from 2013 to 2014. The Ped-RESCUERS model from the development dataset had an AUC of 0.690, and the validation dataset had an AUC of 0.634.

CONCLUSIONS

Ped-RESCUERS provides a novel measure of pre-ECMO mortality risk. Future studies should seek external validation and improved discrimination of this mortality prediction tool.

Heart rate variability analysis is more sensitive at identifying neonatal sepsis than conventional vital signs

BACKGROUND

Sepsis remains the largest preventable source of neonatal mortality in the world. Heart rate variability (HRV) analysis and noninvasive cardiac output have been shown to be useful adjuncts to sepsis detection in many patient groups.

METHODS

With Institutional Review Board approval, 4 septic and 6 nonseptic extremely low birth weight patients were enrolled. Data from septic and healthy patients were collected for 5 hours. Electrocardiogram waveform and traditional vital signs were collected and the RR intervals were calculated; then HRV analysis was performed in both the time and frequency domain.

RESULTS

HRV measurements in time domain, heart rate, and pulse oximetry (SpO2) were significantly different in septic patients vs nonseptic controls.

CONCLUSIONS

These results indicate that nonconventional vital signs such as HRV are more sensitive than traditionally used vital signs, such as cardiac output and mean arterial pressure, in the confirmation of sepsis in extremely low birth weight neonates. HRV may allow for earlier identification of septic physiology.

Diffuse alveolar damage associated mortality in selected acute respiratory distress syndrome patients with open lung biopsy

Introduction

Diffuse alveolar damage (DAD) is the pathological hallmark of acute respiratory distress syndrome (ARDS), however, the presence of DAD in the clinical criteria of ARDS patients by Berlin definition is little known. This study is designed to investigate the role of DAD in ARDS patients who underwent open lung biopsy.

Methods

We retrospectively reviewed all ARDS patients who met the Berlin definition and underwent open lung biopsy from January 1999 to January 2014 in a referred medical center. DAD is characterized by hyaline membrane formation, lung edema, inflammation, hemorrhage and alveolar epithelial cell injury. Clinical data including baseline characteristics, severity of ARDS, clinical and pathological diagnoses, and survival outcomes were analyzed.

Results

A total of 1838 patients with ARDS were identified and open lung biopsies were performed on 101 patients (5.5 %) during the study period. Of these 101 patients, the severity of ARDS on diagnosis was mild of 16.8 %, moderate of 56.5 % and severe of 26.7 %. The hospital mortality rate was not significant difference between the three groups (64.7 % vs 61.4 % vs 55.6 %, p = 0.81). Of the 101 clinical ARDS patients with open lung biopsies, 56.4 % (57/101) patients had DAD according to biopsy results. The proportion of DAD were 76.5 % (13/17) in mild, 56.1 % (32/57) in moderate and 44.4 % (12/27) in severe ARDS and there is no significant difference between the three groups (p = 0.113). Pathological findings of DAD patients had a higher hospital mortality rate than non-DAD patients (71.9 % vs 45.5 %, p = 0.007). Pathological findings of DAD (odds ratio: 3.554, 95 % CI, 1.385–9.12; p = 0.008) and Sequential Organ Failure Assessment score on the biopsy day (odds ratio: 1.424, 95 % CI, 1.187–1.707; p<0.001) were significantly and independently associated with hospital mortality. The baseline demographics and clinical characteristics were not significantly different between DAD and non-DAD patients.

Conclusions

The correlation of pathological findings of DAD and ARDS diagnosed by Berlin definition is modest. A pathological finding of DAD in ARDS patients is associated with hospital mortality and there are no clinical characteristics that could identify DAD patients before open lung biopsy.

Association between tidal volume size, duration of ventilation, and sedation needs in patients without acute respiratory distress syndrome: an individual patient data meta-analysis

PURPOSE

Mechanical ventilation with lower tidal volumes (≤6 ml/kg of predicted body weight, PBW) could benefit patients without acute respiratory distress syndrome (ARDS). However, tidal volume reduction could be associated with increased patient discomfort and sedation needs, and consequent longer duration of ventilation. The aim of this individual patient data meta-analysis was to assess the associations between tidal volume size, duration of mechanical ventilation, and sedation needs in patients without ARDS.

METHODS

Studies comparing ventilation with different tidal volume sizes in patients without ARDS were screened for inclusion. Corresponding authors were asked to provide individual participant data. Patients were assigned to three groups based on tidal volume size (≤6 ml/kg PBW, 6-10 ml/kg PBW, or ≥10 ml/kg PBW). Ventilator-free days, alive at day 28, and dose and duration of sedation (propofol and midazolam), analgesia (fentanyl and morphine), and neuromuscular blockade (NMB) were compared.

RESULTS

Seven investigations (2,184 patients) were included in the analysis. The number of patients breathing without assistance by day 28 was higher in the group ventilated with tidal volume ≤6 ml/kg PBW compared to those ventilated with tidal volume ≥10 ml/kg PBW (93.1 vs. 88.6%; p = 0.027, respectively). Only two investigations (187 patients) could be included in the meta-analysis of sedation needs. There were neither differences in the percentage of study days that patients received sedatives, opioids, or NMBA nor in the total dose of benzodiazepines, propofol, opioids, and NMBA.

CONCLUSIONS

This meta-analysis suggests that use of lower tidal volumes in patients without ARDS at the onset of mechanical ventilation could be associated with shorter duration of ventilation. Use of lower tidal volumes seems not to affect sedation or analgesia needs, but this must be confirmed in a robust, well-powered randomized controlled trial.

Ventilation distribution measured with EIT at varying levels of pressure support and Neurally Adjusted Ventilatory Assist in patients with ALI

PURPOSE

The purpose of this study was to compare the effect of varying levels of assist during pressure support (PSV) and Neurally Adjusted Ventilatory Assist (NAVA) on the aeration of the dependent and non-dependent lung regions by means of Electrical Impedance Tomography (EIT).

METHODS

We studied ten mechanically ventilated patients with Acute Lung Injury (ALI). Positive-End Expiratory Pressure (PEEP) and PSV levels were both 10 cm H₂O during the initial PSV step. Thereafter, we changed the inspiratory pressure to 15 and 5 cm H₂O during PSV. The electrical activity of the diaphragm (EAdi) during pressure support ten was used to define the initial NAVA gain (100 %). Thereafter, we changed NAVA gain to 150 and 50 %, respectively. After each step the assist level was switched back to PSV 10 cm H₂O or NAVA 100 % to get a new baseline. The EIT registration was performed continuously.

RESULTS

Tidal impedance variation significantly decreased during descending PSV levels within patients, whereas not during NAVA. The dorsal-to-ventral impedance distribution, expressed according to the center of gravity index, was lower during PSV compared to NAVA. Ventilation contribution of the dependent lung region was equally in balance with the non-dependent lung region during PSV 5 cm H₂O, NAVA 50 and 100 %.

CONCLUSION

Neurally Adjusted Ventilatory Assist ventilation had a beneficial effect on the ventilation of the dependent lung region and showed less over-assistance compared to PSV in patients with ALI.