Haitham S. Al Ashry

Humidification during Mechanical Ventilation in the Adult Patient

Humidification of inhaled gases has been standard of care in mechanical ventilation for a long period of time. More than a century ago, a variety of reports described important airway damage by applying dry gases during artificial ventilation. Consequently, respiratory care providers have been utilizing external humidifiers to compensate for the lack of natural humidification mechanisms when the upper airway is bypassed. Particularly, active and passive humidification devices have rapidly evolved. Sophisticated systems composed of reservoirs, wires, heating devices, and other elements have become part of our usual armamentarium in the intensive care unit. Therefore, basic knowledge of the mechanisms of action of each of these devices, as well as their advantages and disadvantages, becomes a necessity for the respiratory care and intensive care practitioner. In this paper, we review current methods of airway humidification during invasive mechanical ventilation of adult patients. We describe a variety of devices and describe the eventual applications according to specific clinical conditions.

Incidence of ventilator associated pneumonia in burn patients with inhalation injury treated with high frequency percussive ventilation versus volume control ventilation: A systematic review

BACKGROUND Pneumonia increases mortality in burn patients with inhalation injuries. We evaluated whether the use of High Frequency Percussive Ventilation (HFPV) in burn patients with inhalation injuries can decrease rates of Ventilator Associated Pneumonia (VAP) compared to Volume Control Ventilation (VCV). METHODS Data were gathered from PubMed, EMBASE, Web of Science, reference lists, and hand search. For unpublished data we searched ClinicalTrials.gov and RePORTER. We included observational and Randomized Controlled Trials (RCTs) that compared rates of VAP with the use of HFPV and VCV in adult burn patients with inhalation injury. Two reviewers independently extracted data from the retrieved studies and assessed them for eligibility, methodology, and quality. RESULTS 281 abstracts were reviewed, of which 4 studies (540 patients) were included. Two were observational and two were RCTs. All studies had moderate risk of bias. One study had low external validity while others had moderate external validity. The two observational studies found non-concordant results. One study found a 24% statistically significant reduction in the rates of VAP while the other found no difference. The two RCTs had small sample sizes. There was no significant difference in VAP rates between HFPV and VCV. The VCV arms of the four studies were heterogeneous. Only one study used low tidal volumes, whereas the rest used high tidal volumes in the VCV arm. CONCLUSION Evidence about decreased incidence of VAP in burn patients with inhalation injuries who are on HFPV compared to those on VCV is inconclusive. Although enhanced airway clearance by HFPV was thought to play a role in decreasing VAP in this population, high tidal volume in the VCV arms could be a confounding factor that should be eliminated in future studies before a firm conclusion can be reached. More RCTs comparing HFPV to low tidal volume VCV are needed.

COPD in individuals with the PiMZ alpha-1 antitrypsin genotype

Since the discovery of severe alpha-1 antitrypsin deficiency as a genetic risk factor for emphysema, there has been ongoing debate over whether individuals with intermediate deficiency with one protease inhibitor Z allele (PiMZ, or MZ) are at some risk for emphysema. This is important, because MZ individuals comprise 2–5% of the general population. In this review we summarise the evidence about the risks of the MZ population to develop emphysema or asthma. We discuss the different study designs that have tried to answer this question. The risk of emphysema is more pronounced in case–control than in population-based studies, perhaps due to inadequate power. Carefully designed family studies show an increased risk of emphysema in MZ smokers. This is supported by the rapid decline in lung function of MZ individuals when compared to the general population after massive environmental exposures. The risk of asthma in MZ subjects is less studied, and more literature is needed before firm conclusions can be made. Augmentation therapy in MZ individuals is not supported by any objective studies. MZ smokers are at increased risk for emphysema that is more pronounced when other environmental challenges are present. MZ smokers are at increased risk for emphysema http://ow.ly/ur6f30fufZ1

Emergency Department Blood Gas Utilization and Changes in Ventilator Settings

BACKGROUND: Mechanically ventilated patients increasingly spend hours in emergency department beds before ICU admission. This study evaluated the performance of blood gases in mechanically ventilated subjects in the emergency department and subsequent changes to mechanical ventilation settings. METHODS: This was a multi-center, prospective, observational study of subjects ventilated in the emergency department, conducted at 3 academic emergency departments from July 2011 to March 2013. We measured the rate of arterial blood gas (ABG) and venous blood gas (VBG) analysis, and we assessed the associations between the conditions of hypoxemia, hyperoxia, hypercapnia, or acidemia and changes to mechanical ventilator settings. RESULTS: Of 292 ventilated subjects, 17.1% did not have a blood gas sent in the emergency department. Ventilator changes were made significantly more frequently for subjects who had an ABG as the initial blood gas sent in the emergency department (odds ratio 2.70, 95% CI 1.46–4.99, P = .002). However, findings of hypoxemia, hyperoxia, hypercapnia, or acidemia were not correlated with ventilator adjustments. CONCLUSIONS: In this prospective observational study of subjects mechanically ventilated in the emergency department, the majority had a blood gas checked while in the emergency department. While ABGs were associated with having changes made to ventilator settings in the emergency department, clinical findings of hypoxemia, hyperoxia, hypercapnia, and acidemia were not. Inattention to blood gas results may lead to missed opportunities in guiding ventilator changes in the emergency department.

Sequencing Alpha-1 MZ Individuals Shows Frequent Biallelic Mutations

Rationale Individuals with a single Z mutation in the SERPINA1 gene that codes for alpha-1 antitrypsin (AAT) are at increased risk for COPD if they have ever-smoked. Whether additional variants alter the risk for COPD in this population remains unknown. Objectives To determine whether additional SERPINA1 variants impact COPD development in a previously identified MZ (carrier) cohort. Methods Individuals with prior MZ results and AAT serum level <16uM were recruited from the Alpha-1 Coded Testing study and Alpha-1 Foundation Research Registry. Participants completed smoking history, demographics, and COPD Severity Score (Range 0-33) using REDCap data capture. At-home finger-stick tests were performed for next generation sequencing (NGS) at the Biocerna LLC laboratory. A genetic counselor reviewed records and interviewed participants with additional variants by NGS. A Wilcoxon Rank Sum test was used to assess correlation between variants and the COPD severity score. Results A second SERPINA1 variant of known or possible significance was identified in 6 (5.8%) participants. One each of ZZ, SZ, FZ, ZSmunich, ZM2obernburg, and Z/c.922G>T genotypes were identified. ZZ, SZ, and FZ are known pathogenic genotypes. Smunich is a likely pathogenic variant. M2obernburg and c.922G>T are variants of uncertain significance. The ZZ individual was on augmentation therapy when determined MZ by protease inhibitor (Pi) phenotyping; the others had limited targeted genotyping with MZ results. These six participants with biallelic variants had positive COPD severity scores >1. Presence of additional variants was not significantly associated with COPD symptoms in this small sample size. Conclusions Some diagnosed MZ individuals instead have biallelic variants. Larger studies are needed to determine COPD-risk liability of variants. Accurate diagnosis impacts medical management and familial risk assessment. Pi phenotyping can be confounded by augmentation therapy and liver transplantation. Because a normal M allele may be reported in the absence of tested mutation(s) in AATD genotyping, clinicians should consider clinical circumstances and laboratory methods when selecting and interpreting AATD tests. Advanced testing, including NGS, may be beneficial for select individuals with prior MZ results. Clinical Trial Registration This study was registered with clinicaltrials.gov (NCT NCT02810327).

Duration of Mechanical Ventilation in the Emergency Department

Introduction Due to hospital crowding, mechanically ventilated patients are increasingly spending hours boarding in emergency departments (ED) before intensive care unit (ICU) admission. This study aims to evaluate the association between time ventilated in the ED and in-hospital mortality, duration of mechanical ventilation, ICU and hospital length of stay (LOS). Methods This was a multi-center, prospective, observational study of patients ventilated in the ED, conducted at three academic Level I Trauma Centers from July 2011 to March 2013. All consecutive adult patients on invasive mechanical ventilation were eligible for enrollment. We performed a Cox regression to assess for a mortality effect for mechanically ventilated patients with each hour of increasing LOS in the ED and multivariable regression analyses to assess for independently significant contributors to in-hospital mortality. Our primary outcome was in-hospital mortality, with secondary outcomes of ventilator days, ICU LOS and hospital LOS. We further commented on use of lung protective ventilation and frequency of ventilator changes made in this cohort. Results We enrolled 535 patients, of whom 525 met all inclusion criteria. Altered mental status without respiratory pathology was the most common reason for intubation, followed by trauma and respiratory failure. Using iterated Cox regression, a mortality effect occurred at ED time of mechanical ventilation > 7 hours, and the longer ED stay was also associated with a longer total duration of intubation. However, adjusted multivariable regression analysis demonstrated only older age and admission to the neurosciences ICU as independently associated with increased mortality. Of interest, only 23.8% of patients ventilated in the ED for over seven hours had changes made to their ventilator. Conclusion In a prospective observational study of patients mechanically ventilated in the ED, there was a significant mortality benefit to expedited transfer of patients into an appropriate ICU setting.

Cardiac Invasion by a Mixed Germ Cell Tumor

CASE PRESENTATION A 34-year-old man presented with acute-onset chest pain and respiratory distress. Electrocardiogram showed inferolateral ST elevation, and bedside echocardiogram revealed a moderate pericardial effusion. Emergent coronary angiogram did not demonstrate coronary lesions. Pericardiocentesis was performed and a bloody effusion was drained. Computed tomography angiography of the aorta was obtained to assess for aortic dissection as a cause of hemopericardium, but no dissection was identified. Instead, a 15-cm heterogeneous mediastinal mass was found, causing severe compression of the right atrium and right pulmonary artery. Figure A demonstrates the mass invading the right atrium and Figure B shows the compressed right pulmonary artery. The mass’s Hounsfield units ranged from 30-50, raising concern for mediastinal hematoma. Emergent surgical exploration revealed an actively bleeding anterior mediastinal mass invading the right atrium. Biopsy confirmed a mixed germ cell tumor with 85% nonseminomatous components. Alpha fetoprotein was 1,162 IU/mL. Testicular ultrasound and computed tomography scans of abdomen and pelvis showed

Response to Letter to the Editor regarding “Incidence of ventilator associated pneumonia in burn patients with inhalation injury treated with high frequency percussive ventilation versus volume control ventilation: A systematic review”

We appreciate the valuable commentary by Graham and Huzar on our recently published article [1]. Graham and Huzar mentioned that High Frequency Percussive Ventilation (HFPV) is safe and effective in treating inhalation injuries and then cited Reper et al. paper that showed improvement of gas exchange [2]. While we agree that gas exchange may improve with HFPV, this is not the same as clinical safety or efficacy. That being said, our systematic review was specifically looking at the incidence of pneumonia when HFPV was used in comparison to Volume Controlled Ventilation (VCV). They stated that HFPV decreases the incidence of pneumonia citing the study by Cioffi et al. [3]. This study compared a group of five patients that received VCV and then was switched to HFPV to a group of eight patients prospectively treated with HFPV. We didn’t include this study in our analysis for various reasons. The most obvious reason is that the first group that comprised five patients had three children (ages 1–5). In our review one of our exclusion criteria was studies that included children. Our aim was to focus on adults since outcomes of burn injuries differ between adults as compared to children. In fact, some studies suggest that mortality from burn injuries is much higher in the pediatric population especially for ages less than 4 years [4,5]. We actually included studies with larger sample size than Cioffi et al., so we are not against HFPV as what might be understood from the letter by Graham and Huzar. We clearly pointed out that the results of Chung et al. study that is included in our analysis might have changed more in favor of HFPV if they didn’t have nine patients crossed over from the VCV to the HFPV arm [6]. Saying that the evidence of decreased incidence of pneumonia with HFPV when compared to VCV is inconclusive is not like saying it doesn’t decrease pneumonia. As reported in our paper, more studies are needed. In three of the four studies we included in our systematic review the duration of mechanical ventilation was not statistically different between HFPV and VCV. In the fourth study the duration of mechanical ventilation was not reported. The letter’s authors stated that a randomized trial would be “difficult to obtain clinical equipoise” at many centers because HFPV is typically the “usual practice . . . ”. We respectfully disagree. The intensive care field has had numerous examples of “usual practice” that have proven to be useless or even harmful; as a real example (of so many), the Swan-Ganz catheter, which was the “usual practice” for many years. In conclusion, the results of our systematic review are robust and demonstrate that there is equipoise for future studies. If we want to provide the best care to our burn patients, we ought to aim for the best evidence: more randomized clinical trials comparing HFPV to low tidal volume VCV.

Effect of Compliance With a Nurse-Led Intensive Care Unit Checklist on Clinical Outcomes in Mechanically and Nonmechanically Ventilated Patients:

Background: Use of checklists brings about improvements in a variety of patient outcomes. Nevertheless, whether compliance with a nurse-led intensive care unit (ICU) checklist produces the same effect is currently unknown. Methods: This is a retrospective analysis of data obtained during the implementation of a quality improvement project consisting of the utilization of a nurse-led ICU checklist. A consecutive series of checklists obtained from patients admitted in our ICU during 7 consecutive months were included. The ICU stay, hospital stay, and ventilator stay were compared between patients whose practitioners completed or did not complete the checklist. Variables were analyzed using Mann-Whitney U tests for continuous variables and Fisher exact tests for categorical variables. A 2-tailed P < .05 was considered statistically significant. Results: One thousand checklists, corresponding to 346 eligible patients, were collected over 7 months. Mechanical ventilation was used in 203 (59%) patients. Completed checklists were observed for 37.6% (n = 130) of all patients and 38.9% (n = 79) of mechanically ventilated patients. After adjusting for age, Acute Physiology and Chronic Health Evaluation II (APACHE II), body mass index, reason for admission, and type of ICU, completion of the checklist was associated with a 20% increase in the number of days in the ICU compared with the group with incomplete lists. In mechanically ventilated patients, completion of the checklist was associated with a 31% increase in hospital length of stay, a 34% increase in the number of ICU days, and a 32% increase in mechanical ventilation days. Conclusion: Compliance with completion of a nurse-led ICU checklist was associated with prolonged ICU stay, hospital stay, and ventilator stay.