Hot in Journal CHEST® December 2018
By: Kamran Boka, MD
December 10, 2018
Each month, we ask our Social Media Co-Editors of CHEST to weigh in on the hot topics in CHEST. It's December, so let's hear from Dr. Boka as he outlines his highlights. After reviewing the issue, be sure to share your hot list on our Facebook wall, tweet with the hashtag #journalCHEST, or discuss in the CHEST LinkedIn group.
Persistently Low ScVO2
One of my favorite questions to ask trainees on rounds is to explain how different clinical scenarios affect the oxygen-carrying capacity of Svo2 vs Scvo2. Not only does this exercise provide an opportunity for residents to review hemodynamics and understand how pathology affects physiology, but it also educates on a commonly used ICU bedside tool for diagnosis.
The curious concept of using central venous oxygenation (Scvo2) (and arguably, mixed venous oxygen saturation, or Svo2) for clinical decision-making in sepsis was showcased with Dr. Rivers’ early goal-directed therapy (EGDT) in septic shock in 2001. Patients in his trial were enrolled with initial Scvo2 levels of 49%. Dr. Rivers’ strategy included medically optimizing patients when initial Scvo2 levels lived below 70%. This was, after all, due to the prevailing theory that low Scvo2 is associated with poor prognosis.
Studies have long since supported and substantiated the nearly 20-year practice since EGDT of targeting Scvo2 levels greater than 70%, and, thus, further upheld this theory. However, the Surviving Sepsis Campaign Guidelines no longer recommend initial targeting of Scvo2 due to the negative results of the three multinational randomized controlled trials: ProCESS, ARISE, and PROMISe.
In this month’s CHEST® issue, the ALBIOS investigators revisited their 2014 data, publishing a retrospective analysis of 1,818 patients with sepsis to determine if there is prognostic value of Scvo2. Seeking a primary 90-day mortality endpoint, the authors found mortality rates to be higher in 35% of the low Scvo2 group (<=70%). Persistently lower Scvo2 (defined as more than 6 hours post-resuscitation) was also associated with higher primary endpoint mortality.
Protti A, Masson J, Latini R, et al. Persistence of central venous oxygen desaturation during early sepsis is associated with higher mortality: a retrospective analysis of the ALBIOS trial.
Chest. 2018. 154(6):1291-1300.
Interestingly, patients with Scvo2 levels <70% had higher levels of serum NT-proBNP and hs-cTnT (N-Terminal-pro Brain Natriuretic Peptide, high sensitivity cardiac troponin T), suggesting that the results could be due to cardiac dysfunction.
Asthma/COPD Overlap
It has been well known that asthma/COPD overlap (ACO) syndrome is a phenotype of COPD and that patients with this diagnosis have a higher mortality as compared with patients who have either COPD or asthma alone. However, risk factors for ACO have been and are still poorly defined.
Investigators studying 2,137 firefighters (previously healthy men) who had dust exposure from the World Trade Center were curious about early predictors of ACO. Aware that these rescue workers eventually had developed obstructive ventilatory defects, airway hyperreactivity, and higher rates of lost lung function, the researchers reviewed the post-9/11 FDNY medical blood biomarkers including postexposure blood eosinophil concentrations, serum IgE, cytokines, and IFN-gamma levels.
Their goal? To uncover potential early predictors of ACO.
Figure 3 A-B, Lung function over time. A, Mean ± SEM (SEM not shown if it is smaller than the size of the symbol) FEV1 % predicted in each year between 9/11/2000 and 9/10/2017 in the asthma/COPD overlap (orange), isolated-COPD (gray), isolated-asthma (blue), and asthma-free and COPD-free (red) groups. The vertical line at 0 represents 9/11/2001. The number of spirometries per year is shown below the x-axis. B, Mean FEV1/FVC ratio in the aforementioned groups in each year, adjusted for race, height, and age, using the same number of spirometries per year as shown in panel A.
Singh A, Liu C, Putnam B, et al. Predictors of asthma/COPD overlap inFDNY firefighters with World Trade Center dust exposure: a longitudinal study. Chest. 2018. 154(6):1301-1310.
They found that high eosinophil concentrations and IL-4 levels may predispose patients with ACO to increased inflammation and risk of airway obstruction. This type of study becomes helpful from an epidemiological perspective as it suggests the patient’s own chemistry may predispose to an environmental triggered condition, in this case, irritant-induced ACO.
Bronchiectasis Prevalence Higher Than Thought
I describe bronchiectactic disease to my outpatients through the following exercise: imagine an upside-down oak tree with abnormally dilated grape clusters for twigs. Of course, repleting the visual metaphorical description with a quick sketch helps most of the time.
As difficult it is for many laypersons to understand this diagnosis, it appears that based on the latest article on the epidemiology of bronchiectasis in older Americans, there exists an even higher than previously thought prevalence of the disease, including misdiagnosis by nonspecialists and nonscreening by most primary care physicians.
By using the Medicare fee-for-service population, Henkle et al reviewed (Chest. 2018. 154[6]:1311-1320) older Americans aged 65 years of age or greater for a pulmonologist-documented billing code of bronchiectasis (non-cystic-fibrosis) and found their suspicions to be true: a higher than previously thought prevalence of non-CF bronchiectasis exists.
Interesting findings included that women were found to have a higher presence of disease.
Learn more in the podcast.