Correlation of urinary excretion of sodium with severity of sleep-disordered breathing in children: a preliminary study

Nocturnal enuresis is associated with moderate-to-severe obstructive sleep apnea in children with snoring

BACKGROUND

Conflicting data suggest that prevalence of monosymptomatic primary nocturnal enuresis (NE) increases with increasing severity of obstructive sleep apnea (OSA) in childhood and especially in girls. We hypothesized that NE is associated with increased risk of moderate-to-severe OSA (obstructive apnea-hypopnea index (AHI) >5 episodes/hour) among children with snoring.

METHODS

Data of children (≥5 y old) with snoring who were referred for polysomnography over 12 y were reviewed.

RESULTS

Data of 525 children with mean age (±SD) 7.5 (± 2.2) y and median obstructive AHI (10th-90th percentiles) 1.9 (0.4-7.3) episodes/hour were analyzed. Three hundred and fifty-five children (67.6%) had NE and 87 (16.6%) had moderate-to-severe OSA. There was no interaction between NE and gender regarding the association with moderate-to-severe OSA (P > 0.05). NE was associated significantly with presence of moderate-to-severe OSA after adjustment for tonsillar hypertrophy, obesity, gender, and age (adjusted odds ratio = 1.92 (1.08-3.43); P = 0.03). Presence of NE had high sensitivity (78.2%) and low positive predictive value (19.2%) for detecting moderate-to-severe OSA and low specificity (34.5%) and high negative predictive value (88.8%) for ruling it out.

CONCLUSION

Children with snoring and without NE referred for polysomnography are less likely to have moderate-to-severe OSA compared to those with NE.

Angiotensin II Type 1 Receptors and Systemic Hemodynamic and Renal Responses to Stress and Altered Blood Volume in Conscious Rabbits

We examined how systemic blockade of type 1 angiotensin (AT(1)-) receptors affects reflex control of the circulation and the kidney. In conscious rabbits, the effects of candesartan on responses of systemic and renal hemodynamics and renal excretory function to acute hypoxia, mild hemorrhage, and plasma volume expansion were tested. Candesartan reduced resting mean arterial pressure (MAP, -8 ± 2%) without significantly altering cardiac output (CO), increased renal blood flow (RBF, +38 ± 9%) and reduced renal vascular resistance (RVR, -32 ± 6%). Glomerular filtration rate (GFR) was not significantly altered but sodium excretion (U(Na+)V) increased fourfold. After vehicle treatment, hypoxia (10% inspired O(2) for 30 min) did not significantly alter MAP or CO, but reduced heart rate (HR, -17 ± 6%), increased RVR (+33 ± 16%) and reduced GFR (-46 ± 16%) and U(Na+)V (-41 ± 17%). Candesartan did not significantly alter these responses. After vehicle treatment, plasma volume expansion increased CO (+35 ± 7%), reduced total peripheral resistance (TPR, -26 ± 5%), increased RBF (+62 ± 23%) and reduced RVR (-32 ± 9%), but did not significantly alter MAP or HR. It also increased U(Na+)V (803 ± 184%) yet reduced GFR (-47 ± 9%). Candesartan did not significantly alter these responses. After vehicle treatment, mild hemorrhage did not significantly alter MAP but increased HR (+16 ± 3%), reduced CO (-16 ± 4%) and RBF (-18 ± 6%), increased TPR (+18 ± 4%) and tended to increase RVR (+18 ± 9%, P = 0.1), but had little effect on GFR or U(Na+)V. But after candesartan treatment MAP fell during hemorrhage (-19 ± 1%), while neither TPR nor RVR increased, and GFR (-64 ± 18%) and U(Na+)V (-83 ± 10%) fell. AT(1)-receptor activation supports MAP and GFR during hypovolemia. But AT(1)-receptors appear to play little role in the renal vasoconstriction, hypofiltration, and antinatriuresis accompanying hypoxia, or the systemic and renal vasodilatation and natriuresis accompanying plasma volume expansion.