Effect of continuous positive airway pressure on maximal exercise capacity in patients with obstructive sleep apnea: a systematic review and meta-analysis

STUDY OBJECTIVES

Exercise capacity is impaired in obstructive sleep apnea (OSA). There are conflicting reports on the effect of continuous positive airway pressure (CPAP) on maximal exercise capacity. The objective of this review was to determine if there is a change in exercise capacity and anaerobic threshold following CPAP treatment in OSA patients.

METHODS

We conducted a systematic review and meta-analyses to summarize the changes in peak rate of oxygen uptake (V̇O₂ peak) or maximum rate of oxygen uptake (V̇O2 max) and anaerobic threshold (AT) during cardiopulmonary exercise testing following CPAP intervention in patients with OSA. A systematic literature review was conducted to identify published literature on markers of V̇O₂ peak, V̇O₂ max, and AT pre- vs post-CPAP using a web-based literature search of PubMed/MEDLINE, Embase, CINAHL, and Cochrane review (CENTRAL) databases. Two independent reviewers screened the articles for data extraction and analysis.

RESULTS

The total search of all the databases returned 470 relevant citations. Following application of eligibility criteria, 6 studies were included in the final meta-analysis for V̇O₂ peak, 2 studies for V̇O₂ max, and five studies for AT. The meta-analysis showed a mean net difference in V̇O₂ peak between pre- and post-CPAP of 2.69 mL·kg^-1·min^-1, P = .02, favoring treatment with CPAP. There was no difference in V̇O₂ max or AT with CPAP treatment (mean net difference 0.66 mL·kg^-1·min^-1 [P = .78] and -144.98 mL·min^-1 [P = .20] respectively).

CONCLUSIONS

There is a paucity of high-quality studies investigating the effect of CPAP on exercise capacity. Our meta-analysis shows that V̇O₂ peak increases following CPAP treatment in patients with OSA, but we did not observe any change in V̇O₂ max or AT. Our findings should be considered preliminary and we recommend further randomized controlled trials to confirm our findings and to clarify the peak and maximum rates of oxygen uptake adaptations with CPAP therapy.

Offline eLearning for undergraduates in health professions: A systematic review of the impact on knowledge, skills, attitudes and satisfaction

BACKGROUND

The world is short of 7.2 million health-care workers and this figure is growing. The shortage of teachers is even greater, which limits traditional education modes. eLearning may help overcome this training need. Offline eLearning is useful in remote and resource-limited settings with poor internet access. To inform investments in offline eLearning, we need to establish its effectiveness in terms of gaining knowledge and skills, students' satisfaction and attitudes towards eLearning.

METHODS

We conducted a systematic review of offline eLearning for students enrolled in undergraduate, health-related university degrees. We included randomised controlled trials that compared offline eLearning to traditional learning or an alternative eLearning method. We searched the major bibliographic databases in August 2013 to identify articles that focused primarily on students' knowledge, skills, satisfaction and attitudes toward eLearning, and health economic information and adverse effects as secondary outcomes. We also searched reference lists of relevant studies. Two reviewers independently extracted data from the included studies. We synthesized the findings using a thematic summary approach.

FINDINGS

Forty-nine studies, including 4955 students enrolled in undergraduate medical, dentistry, nursing, psychology, or physical therapy studies, met the inclusion criteria. Eleven of the 33 studies testing knowledge gains found significantly higher gains in the eLearning intervention groups compared to traditional learning, whereas 21 did not detect significant differences or found mixed results. One study did not test for differences. Eight studies detected significantly higher skill gains in the eLearning intervention groups, whilst the other 5 testing skill gains did not detect differences between groups. No study found offline eLearning as inferior. Generally no differences in attitudes or preference of eLearning over traditional learning were observed. No clear trends were found in the comparison of different modes of eLearning. Most of the studies were small and subject to several biases.

CONCLUSIONS

Our results suggest that offline eLearning is equivalent and possibly superior to traditional learning regarding knowledge, skills, attitudes and satisfaction. Although a robust conclusion cannot be drawn due to variable quality of the evidence, these results justify further investment into offline eLearning to address the global health care workforce shortage.

Why are East Asians more susceptible to several infection-associated cancers (carcinomas of the nasopharynx, stomach, liver, adenocarcinoma of the lung, nasal NK/T-cell lymphomas)?

There are at least five cancers with uniquely high incidence amongst East and Southeast Asian ethnic groups - namely nasopharyngeal carcinoma (NPC); gastric carcinoma; hepatocellular carcinoma (HCC); adeno-carcinoma of the lung in female non-smokers and nasal NK/T-cell lymphomas. They all appear to be related to an infective cause (Epstein Barr Virus, Helicobacter pylori, hepatitis B virus). We hypothesize that a genetic bottleneck 30,000years ago at the Last Glacial Maximum could have resulted in unique genetic polymorphisms in Toll-like receptor 8, making East Asians more vulnerable to these infective associated cancers. This bottleneck could have been caused by the presence of malaria in the southern Himalayan conduit between central and East Asia; and only those with an attenuated innate immune response to the malarial parasite (perhaps reflected by the TLR8 polymorphism) were spared the ravages of cerebral malaria; allowing these people to cross into east Asia, but then rendering them susceptible to later endemic infections and their associated cancers.

Why are East Asians more susceptible to several infection-associated cancers (carcinomas of the nasopharynx, stomach, liver, adenocarcinoma of the lung, nasal NK/T-cell lymphomas)?

There are at least five cancers with uniquely high incidence amongst East and Southeast Asian ethnic groups - namely nasopharyngeal carcinoma (NPC); gastric carcinoma; hepatocellular carcinoma (HCC); adeno-carcinoma of the lung in female non-smokers and nasal NK/T-cell lymphomas. They all appear to be related to an infective cause (Epstein Barr Virus, Helicobacter pylori, hepatitis B virus). We hypothesize that a genetic bottleneck 30,000years ago at the Last Glacial Maximum could have resulted in unique genetic polymorphisms in Toll-like receptor 8, making East Asians more vulnerable to these infective associated cancers. This bottleneck could have been caused by the presence of malaria in the southern Himalayan conduit between central and East Asia; and only those with an attenuated innate immune response to the malarial parasite (perhaps reflected by the TLR8 polymorphism) were spared the ravages of cerebral malaria; allowing these people to cross into east Asia, but then rendering them susceptible to later endemic infections and their associated cancers.