Clinical Adult Literature Updates from December 2018

Comparison of apnoea–hypopnoea index and oxygen desaturation index when identifying obstructive sleep apnoea using type‐4 sleep studies.

Current gold-standard approaches for obstructive sleep apnea (OSA) detection and diagnosis are intrusive, have logistical and financial constraints and can affect the patient’s sleep quality. Type-4 devices have been increasingly used in the setting of resource limitations.


The authors aimed to investigate the correlation (Kappa coefficient) between flow based apnea-hypopnea index (AHIflow50%) and oxygen desaturation index 3% (ODI3%) when concurrently measured using a two-channel ApnealinkTM portable sleep study device in a sample of patients from the general population. They sought to determine if both indices can be used interchangeably.


296 out of an initial 772 patients that had both airflow and oxygen saturation recordings of at least 4 hours were included for analysis. The mean age was 53 years, mean body mass index (BMI) of 29 kg/m2, with 48% being male. Results yielded a median AHIflow50% of 5 (interquartile range 2,10) and median ODI3% of 9 (interquartile range 4,15). The authors found that the AHIflow50% based on airflow alone tended to underestimate obstructive sleep apnea compared to ODI3%. The concordance between AHIflow50% and ODI3% for the diagnosis of OSA and severity classification was 0.32 (moderately discordant), with variations when gender and BMI subgroups were analyzed (worse for increasing BMI and worse for females). The authors suggested caution when using ODI3% as the measure of choice for Type-4 portable sleep studies until further evidence emerges.”


DOI: 10.1111/jsr.12804

Risk factors for admission after shoulder arthroscopy

This retrospective review of all consecutive shoulder arthroscopy procedures performed during a 10 year period used a 2:1 control-case matching technique and univariate and multivariate analysis to identify variables associated with admission. Of the 5,598 arthroscopic procedures, 4.2% required admission. The most common reason for admission was respiratory monitoring, OSA increased the odds (OR 1.90) for admission after shoulder surgery. Increasing body mass index, increased age, COPD, diabetes and increased operative times were risk factors for admission. The absence of general anesthesia reduced the risk of admission.

Risk factors for opioid-induced respiratory depression in surgical patients: a systematic review and meta-analyses

This systematic review and meta-analysis included 12 observational studies. The incidence of postoperative opioid-induced respiratory depression (OIRD) was 5.0 cases per 1000 anesthetics. Eight-five percent of OIRD occurred within the first 24 hours after surgery. Risk factors for OIRD included pre-existing cardiac disease, pulmonary disease, and obstructive sleep apnea. The morphine equivalent daily dose of the postoperative opioids was higher in the OIRD than the control groups.

Hypercapnia impaired cognitive and memory functions in obese patients with obstructive sleep apnoea

In this prospective study, 39 obese patients (BMI ≥ 30) with moderate to severe OSA were enrolled. All patients underwent polysomnography, had an arterial blood gas and completed neurocognitive tests before treatment of OSA. Fifteen patients were found to be hypercapneic and considered to have obesity hypoventilation syndrome. These patients had deficits in logical memory and attention and increased reaction times when compared to non-hypercapneic patients with OSA.