Congenital dyserythropoietic anemia type II — a case report of two siblings in a family

Two children out of three siblings of a family presented with tiredness, fatigue, and breathlessness for more than 6 months. Examination of peripheral blood smear, bone marrow aspirate, and a positive acidified serum test (HEMPAS) revealed these children to be a case of congenital dyserythropoietic anemia type II. This case is reported because of its rarity.     

End-expiratory lung volume decreases during REM sleep despite continuous positive airway pressure

Sleep and Breathing - Patients with obstructive sleep apnea (OSA) may experience apneas and hypopneas primarily during stage R (REM) sleep when end-expiratory lung volume (EELV) reaches its nadir....     

Markers of lung disease in exhaled breath: nitric oxide

Management of airway inflammation requires proper monitoring and treatment to improve long-term outcomes. However, achieving this goal is difficult, as current methods have limitations. Although nitric oxide (NO) was first identified 200 years ago, its physiological importance was not recognized until the early 1980s. Many studies have established the role of NO as an essential messenger molecule in body systems. In addition, studies have demonstrated a significant relationship between changes in exhaled NO levels and other markers of airway inflammation. The technique used to measure NO in exhaled breath is noninvasive, reproducible, sensitive, and easy to perform. Consequently, there is growing interest in the use of exhaled NO in the management of asthma and other pulmonary conditions. The purpose of this review is to promote a basic understanding of the physiologic actions of NO, measurement techniques, and ways that research findings might translate to future application in clinical practice. Specifically, the article will review the role of exhaled NO in regard to its historical background, mechanisms of action, measurement techniques, and implications for clinical practice and research.     

A Method for Determining Optimal Mean Airway Pressure in High-Frequency Oscillatory Ventilation

Background

“Optimal” mean airway pressure (MAP) during high-frequency oscillatory ventilation (HFOV) can be defined as the pressure that allows for maximal alveolar recruitment while minimizing alveolar overdistension. Choosing a MAP near or just below the point of maximal curvature (PMC) of the volume–pressure characteristics of the lung can serve as a guide to avoid overdistention during HFOV, while simultaneously preventing derecruitment. The purpose of this study was to assess whether optimal MAP at the PMC can be determined by using measures of PaO₂ in patients with acute respiratory distress syndrome (ARDS) undergoing HFOV.

Methods

We prospectively studied seven patients with ARDS who underwent HFOV after failed conventional ventilation. In addition, 11 healthy subjects were studied to validate measurements of changes in end-expiratory lung volume (?EELV) using magnetometers. Using this validated method, plots of ?EELV and MAP were constructed during decremental changes in MAP following a recruitment maneuver in seven ventilated patients with ARDS. The PMC was defined as the point where the slope of the ?EELV versus MAP curve acutely changed. The MAP at the PMC was compared to that determined from plots of PaO₂ versus MAP.

Results

In the healthy cohort, measurements of ?EELV obtained by magnetometry approximated the line of identity when compared to those obtained by spirometry. The MAP determined using either the ?EELV or PaO₂ techniques were identical in all seven HFOV ventilated patients. Additionally, there was a significant correlation between the MAP associated changes in PaO2 and the MAP associated changes in ?EELV (p < 0.001).

Conclusions

The finding that MAP at the PMC is the same whether determined by measures of ?EELV or PaO₂ suggest that bedside measures PaO₂ may provide an acceptable surrogate for measures of EELV when determining “optimal” MAP during HFOV.     

Exhaled carbon monoxide as a biomarker of inflammatory lung disease

Carbon monoxide (CO) can be detected on the exhaled breath of humans. Exhaled CO (E-CO) originates from the inspiration of ambient CO and from endogenous metabolic sources that include heme metabolism catalyzed by heme oxygenase (HO) enzymes. HO occurs in both constitutive (HO-2) and inducible (HO-1) forms; the latter responds to pro-inflammatory or pro-oxidative stimuli. E-CO may arise in the airways from inducible HO-1 activity in the bronchial epithelium, alveolar macrophages and other lung cell types, as a consequence of local inflammation, and from the alveolae in equilibrium with carboxyhemoglobin (Hb-CO) in the pulmonary circulation. Elevations in Hb-CO in turn may reflect increases in ambient CO, as well as increased HO activity in systemic tissues. E-CO increases dramatically in active smokers and can be used to monitor the smoking habit. Elevations in E-CO have been observed in critically ill or post-surgical patients and those with various pulmonary diseases associated with inflammation, including chronic obstructive pulmonary disease (COPD), asthma, cystic fibrosis and infections. Despite improvements in the standardization and sensitivity of methods to detect E-CO, the predictive value of this measurement as a diagnostic tool remains unclear.     

Carbon monoxide and human disease

Carbon monoxide is produced endogenously in humans through the breakdown of hemoglobin by heme oxygenase. Although originally thought to be a superfluous by-product of heme catabolism, carbon monoxide is now known to play a central role in many aspects of human health and disease. The functions of carbon monoxide that have been described to date are myriad, including blood pressure regulation, maintenance of organ-specific vascular tone, neurotransmission, stress response, platelet activation, and smooth muscle relaxation. This review outlines what is known to date about carbon monoxide as it relates to human disease.     

The Maximal Expiratory-to-Inspiratory Pressure Ratio and Supine Vital Capacity as Screening Tests for Diaphragm Dysfunction

Purpose

The change in vital capacity from the seated to supine position (?VC-supine) is used to screen for diaphragm dysfunction (DD), but some individuals are unable to tolerate the supine position. Since expiratory muscle function is often preserved in patients with isolated DD and inspiratory strength is reduced, the purpose of this study was to examine if the ratio of maximal expiratory pressure to maximal inspiratory pressure (MEP/MIP) may provide an alternative to ?VC-supine when screening patients for DD.

Methods

We performed a cross-sectional analysis on 76 patients referred for evaluation of unexplained dyspnea and possible DD. MEP and MIP were measured in the seated position as well as the percent change in VC from the seated to supine position (?VC-supine %). The presence of unilateral diaphragm paralysis (UDP), bilateral diaphragm paralysis (BDP), or normal diaphragm function (N) was confirmed by ultrasound.

Results

Of the 76 patients, 23 had N, 40 had UDP, and 13 had BDP. MEP/MIP was significantly greater for UDP compared to N (2.1(1.2–5.7) and 1.5(0.7–2.2), respectively) (median and interquartile range) and for BDP compared to UDP (4.3(2.3–7.5) and 2.1(1.2–5.7), respectively) (p < 0.001). The area (AUC) under the receiver-operating characteristic curve for MEP/MIP between N and UDP was 0.84 (95% confidence interval (CI) 0.74–0.94) and between UDP and BDP was 0.90 (95% CI 0.80–0.99). MEP/MIP had a strong monotonic relationship with ?VC-supine % (Spearman’s ρ = 0.68, p < 0.001).

Conclusions

The MEP/MIP ratio provides a method with comparable sensitivity and specificity to ?VC-supine % that can be used to screen patients with suspected isolated phrenic neuropathy and alleviates the need for measuring supine pulmonary function.

     

Recommendations for Evaluating Temporal Trends of Persistent Organic Pollutants in Breast Milk

Background:

Biomonitoring data of persistent organic pollutants (POPs) in breast milk are increasingly collected and available for quantitative analysis of levels and time trends. A common approach is to apply log-linear regression to calculate doubling and halving times of the POP concentrations based on the temporal trend observed in breast milk. However, there are different, sometimes conflicting interpretations of these doubling and halving times.

Objectives:

We provide a mechanistic understanding of doubling and halving times where possible. Five recommendations are proposed for dealing with POP concentration trends in breast milk during three distinct periods (pre-ban, transition, post-ban period).

Discussion:

Using temporal trends of BDE-47 and PCB-153 in breast milk data, we show which information can be gained from the time-trend data. To this end, we analyzed time trends of hypothetical POPs for different periods with time-variant exposure and different intrinsic elimination half-lives, using a dynamic population-based pharmacokinetic model. Different pieces of information can be extracted from time-trend data from different periods. The analysis of trends of short-lived POPs is rather straightforward and facilitates extraction of the intrinsic elimination half-lives from the breast milk data. However, trends of slowly eliminated POPs only provide indications for the exposure time trend.

Conclusions:

Time-trend data of rapidly eliminated POPs provide information on exposure time trends and elimination half-lives. Temporal trends of slowly eliminated POPs are more complicated to interpret, and the extraction of exposure time trends and elimination half-lives require data sets covering several decades.

Citation:

Gyalpo T, Scheringer M, Hungerbühler K. 2016. Recommendations for evaluating temporal trends of persistent organic pollutants in breast milk. Environ Health Perspect 124:881–885; http://dx.doi.org/10.1289/ehp.1510219     

Cataract surgical coverage and outcome in the Tibet Autonomous Region of China

BACKGROUND: A recently published, population based survey of the Tibet Autonomous Region (TAR) of China reported on low vision, blindness, and blinding conditions. This paper presents detailed findings from that survey regarding cataract, including prevalence, cataract surgical coverage, surgical outcome, and barriers to use of services. METHODS: The Tibet Eye Care Assessment (TECA) was a prevalence survey of people from randomly selected households from three of the seven provinces of the TAR (Lhoka, Nakchu, and Lingzhr), representing its three main environmental regions. The survey, conducted in 1999 and 2000, assessed visual acuity, cause of vision loss, and eye care services. RESULTS: Among the 15,900 people enumerated, 12,644 were examined (79.6%). Cataract prevalence was 5.2% and 13.8%, for the total population, and those over age 50, respectively. Cataract surgical coverage (vision <6/60) for people age 50 and older (85-90% of cataract blind) was 56% overall, 70% for men and 47% for women. The most common barriers to use of cataract surgical services were distance and cost. In the 216 eyes with cataract surgery, 60% were aphakic and 40% were pseudophakic. Pseudophakic surgery left 19% of eyes blind (<6/60) and an additional 20% of eyes with poor vision (6/24-6/60). Aphakic surgery left 24% of eyes blind and an additional 21% of eyes with poor vision. Even though more women remained blind than men, 28% versus 18% respectively, the different was not statistically significant (p = 0.25). CONCLUSIONS: Cataract surgical coverage was remarkably high despite the difficulty of providing services to such an isolated and sparse population. Cataract surgical outcome was poor for both aphakic and pseudophakic surgery. Two main priorities are improving cataract surgical quality and cataract surgical coverage, particularly for women.