Optimum expression of adult lung function based on all-cause mortality: results from the Reykjavik study

A variety of reference curves are used to derive predicted values for adult lung function, even within ethnically similar populations. Alternatives to percentage predicted value are sometimes used to allow for height in research. Strength of association with total mortality can be used to choose the optimal expression, between forced expiratory volume in 1s (FEV(1)) divided by height(2), FEV(1)/height(3), FEV(1)% predicted and difference from predicted. Data from the Reykjavik Study cohort, 1976-2002, included 5544 men and 8062 women randomly selected from the population. Total mortality was analysed by Cox proportional hazards regression in relation to each height-adjusted measure, allowing for age group, period of recruitment and body mass index, and smoking before or at baseline. FEV(1)/height(2) and FEV(1)/height(3) had stronger associations with mortality than FEV(1)% predicted and difference from predicted in men and in women. There were similar findings for forced vital capacity (FVC) in non-smokers and in women. FEV(1)/height(2) was slightly better predictive than FEV(1)/height(3) in men, but distributions of FEV(1)/height(3) in men and women were closer than those of FEV(1)/height(2). Clinical practise and epidemiological research would benefit from agreement on how to adjust lung function for height. Replication of these analyses in other cohort studies would inform the choice between FEV(1)/height(2) and FEV(1)/height(3).     

Effects and Side-Effects of Surgery for Snoring and Obstructive Sleep Apnea – A Systematic Review

Study Objectives:

Many patients undergo surgery for snoring and sleep apnea, although the efficacy and safety of such procedures have not been clearly established. Our aim was systematically to review studies of the efficacy and adverse effects of surgery for snoring and obstructive sleep apnea.

Design:

Systematic review.

Measurements:

PubMed and Cochrane databases were searched in September 2007. Randomized controlled trials of surgery vs. sham surgery or conservative treatment in adults, with daytime sleepiness, quality of life, apnea-hypopnea index, and snoring as outcomes were included. Observational studies were also reviewed to assess adverse effects. Evidence of effect required at least two studies of medium and high quality reporting the same result.

Results:

Four studies of benefits and 45 studies of adverse effects were included. There was no significant effect on daytime sleepiness and quality of life after laser-assisted uvulopalatoplasty and radiofrequency ablation. The apnea-hypopnea index and snoring was reduced in one trial after laser-assisted uvulopalatoplasty but not in another trial. Subjective snoring was reduced in one trial after radiofrequency ablation. No trial investigating the effect of any other surgical modality met the inclusion criteria. Persistent side-effects occurred after uvulopalatopharyngoplasty and uvulopalatoplasty in about half the patients and difficulty in swallowing, globus sensation and voice changes were especially common.

Conclusions:

Only a small number of randomized controlled trials with a limited number of patients assessing some surgical modalities for snoring or sleep apnea are available. These studies do not provide any evidence of effect from laser-assisted uvulopalatoplasty or radiofrequency ablation on daytime sleepiness, apnea reduction, quality of life or snoring. We call for research of randomized, controlled trials of surgery other than uvulopalatopharyngoplasty and uvulopalatoplasty, as they are related to a high risk of long-term side-effects, especially difficulty swallowing.

Citation:

Franklin KA; Anttila H; Axelsson S; Gislason T; Maasilta P; Myhre KI; Rehnqvist N. Effects and side-effects of surgery for snoring and obstructive sleep apnea – a systematic review. SLEEP 2009;32(1):27–36.     

Use of selective cyclooxygenase-2 inhibitors and nonselective nonsteroidal antiinflammatory drugs in high doses increases mortality and risk of reinfarction in patients with prior myocardial infarction

The selective cyclooxygenase-2 (COX-2) inhibitors and other nonselective nonsteroidal antiinflammatory drugs (NSAIDs) have been associated with increased cardiovascular risk, but the risk in patients with established cardiovascular disease is unknown. In the present study, we analyzed the risk of rehospitalization for acute myocardial infarction (re-MI) and death related to the use of NSAIDs including selective COX-2 inhibitors in patients with a prior myocardial infarction (MI). We included 58,432 patients discharged alive after a first MI, and subsequent use of all NSAIDs was identified from a nationwide register of drug dispensing from pharmacies. We found a dose-dependent increase in risk of death for both the selective COX-2 inhibitors and the nonselective NSAIDs (all of the drugs tested). There were trends for increased risk of re-MI associated with the use of both the selective COX-2 inhibitors and the nonselective NSAIDs (high dosages). Selective COX-2 inhibitors in all dosages and nonselective NSAIDs in high dosages should be used with particular caution in patients with a prior MI.     

Comparison of different methods for measuring intra-abdominal pressure

OBJECTIVE: Intra-abdominal pressure (IAP) can be measured in different ways but is usually measured indirectly via the urinary bladder. The aim of the study was to: 1) compare urinary bladder pressure, femoral vein pressure, and inferior caval vein pressure with IAP at different levels of IAP; and 2) try to find an optimal amount of fluid to be instilled into the urinary bladder before measurement of the bladder pressure, and to compare changes in blood flow in the femoral vein with that in the caval vein at different pressure levels. DESIGN: Experimental study. SETTING: Animal research laboratory. SUBJECTS: Eight domestic swine of both sexes, weighing 30.6+/-2.9 kg (mean+/-SD). INTERVENTIONS: Catheters connected to pressure transducers were placed into the urinary bladder, the inferior caval vein, the femoral vein, and the superior caval vein. Transit time flow probes were placed around the inferior caval vein and the femoral vein. After a stabilizing period, the abdominal pressure was increased stepwise by instillation of Ringer's solution into the abdomen and then decreased. Thereafter, we instilled fluid into the bladder at an IAP of 8 mmHg and at 20 mmHg and measured the amount of fluid needed to elevate the intra-vesical pressure by 2 mmHg. RESULTS: The pressures recorded in the urinary bladder, the inferior caval vein, and the femoral vein reflected the pressure in the abdominal cavity very well. The fluid volume needed to increase the bladder pressure by 2 mmHg was significantly lower at 20 mmHg IAP than at 8 mmHg. Blood flow in the femoral vein and the inferior caval vein showed a similar pattern and decreased when the intra-abdominal pressure increased. CONCLUSIONS: In our porcine model, and increasing the IAP by means of instillation of Ringer's solution, a reliable estimation of the IAP was obtained by measuring the pressure in the urinary bladder, the femoral vein or the inferior caval vein. The IAP estimated indirectly as the urinary bladder pressure is affected by the amount of fluid in the bladder, which should not exceed 10-15 ml. The decrease in femoral vein blood flow reflects the changes in inferior caval vein flow during increased IAP.     

Nocturnal nasal obstruction is frequent and reduces sleep quality in patients with obstructive sleep apnea

The prevalence and consequences of nasal obstruction in untreated obstructive sleep apnea patients are not known. The study objectives were to investigate the frequency of subjective and objective nasal obstruction in untreated sleep apnea patients and the associations with sleep and quality of life. Patients in the Icelandic Sleep Apnea Cohort were subjected to a type 3 sleep study, answered questionnaires and had their nasal dimensions measured by acoustic rhinometry. In total, 810 patients participated (including 153 females), aged 54.5 ± 10.6 years [mean ± standard deviation (SD)] with an apnea/hypopnea index 44.7 ± 20.7 h^?1. Nocturnal nasal obstruction (greater than or equal to three times per week) was reported by 35% of the patients. These patients had smaller nasal dimensions measured by the minimum cross‐sectional area within the smaller nasal valve (0.42 ± 0.17 versus 0.45 ± 0.16 cm², P = 0.013), reported more daytime sleepiness (Epworth Sleepiness Scale score 12.5 ± 4.9 versus 10.8 ± 5.0; P < 0.001) and slightly lower mental quality of life than patients without nocturnal nasal obstruction. Nocturnal nasal obstruction is reported in one‐third of the sleep apnea patients and they are more likely to suffer from daytime sleepiness and slightly reduced quality of life than other sleep apnea patients.