Changes in nocturnal oximetry after treatment of exacerbations in cystic fibrosis

Sleep-disordered breathing in cystic fibrosis

Sleep-disordered breathing (SBD) is an under recognized comorbidity in the cystic fibrosis (CF) population across the lifespan. Nocturnal hypoxemia, obstructive sleep apnea, and nocturnal hypoventilation are respiratory abnormalities that occur commonly during sleep in patients with lung disease, and have deleterious consequences to the quality of life in people with CF. Effective screening for these abnormalities is needed to allow for timely initiation of treatment, which has been reported to be efficacious. Lack of treatment leads to worsened pulmonary, cardiovascular, and metabolic outcomes in patients. In this review, we give an overview of SBD for the CF clinician, including prevalence, treatment, and suggestions for future research. We strongly encourage the CF community to incorporate evaluation for SBD in CF clinical care so that outcomes for the subset of the CF patients with comorbid SBD improve.

Nocturnal oximetry in children with obstructive lung disease or sleep-disordered breathing

OBJECTIVES

Although progress has been made in the standardized interpretation of nocturnal oximetry in children with obstructive sleep-disordered breathing (SDB), no evidence exists on oximetry abnormalities in other respiratory disorders. We aimed to compare obstructive lung disease (OLD) and SDB regarding nocturnal oximetry parameters.

METHODS

We analyzed oximetry recordings from children with (i) OLD (obliterative bronchiolitis; cystic fibrosis); (ii) snoring and adenotonsillar hypertrophy (SDB); and (iii) no respiratory disorder (controls). The three groups were compared regarding: (i) oxygen desaturation of hemoglobin index (SpO₂ drops ≥3%/h-ODI3) and (ii) basal SpO₂ (average SpO₂ between SpO₂ drops). The associations of oximetry parameters (natural logarithm) with study group were tested using linear regression including age as covariate.

RESULTS

Data of 16 subjects with OLD (median age: 7.3 years; Q25, Q75: 5.4, 12), 22 children with SDB (6.3 years; 4, 9) and 22 controls (6.8 years; 5.6, 10.3) were analyzed. Children with OLD or SDB had significantly lower basal SpO₂ than controls (91.9% [90.8, 93.4] vs 96.3% [96, 97.4] vs 97.6% [97.1, 97.9]; P < 0.01). No subjects in the SDB or control groups had basal SpO₂  < 95%. Children with SDB had significantly higher ODI3 than children with OLD or controls [8.4 episodes/h (6.2, 16.6) vs 4.4 episodes/h (3.6, 6.6) vs 2 episodes/h (1.3, 2.7); P < 0.01]. OLD had the greatest negative effect on basal SpO₂ (R²  = 0.62; P < 0.001) and SDB the greatest positive effect on ODI3 (R²  = 0.34; P < 0.001).

CONCLUSION

OLD is associated mostly with reduced basal SpO₂ , whereas SDB is characterized by elevated ODI3.

Predictors of sleep hypoxemia in children with cystic fibrosis

OBJECTIVES

To identify the determinants of nocturnal hypoxemia in children with CF using clinical parameters, polysomnography (PSG), and lung function.

HYPOTHESIS

Sleep hypoxemia in children with CF is predicted by both apnea hypopnea index (AHI) and percent predicted forced expiratory volume in one second (pFEV1).

DESIGN

Retrospective case series.

METHODS

Children aged 5-18 years were included based on (i) a diagnosis of CF; and (ii) availability of concurrent PSG and pFEV1 data. The impact of (i) demographic and clinical parameters; and (ii) PSG and pFEV1, on the total sleep time spent with arterial oxygen saturation below 90% (TSpO₂  < 90) was measured using regression analysis. P-value <0.05 was considered significant.

RESULTS

The mean age was 11.6 years (95% confidence interval: 9.5, 13.1). Twenty of 35 (57%) were boys and the mean body mass index percentile was 42.1 (31.5, 52.6). The most common ethnicity was white (66%). OSA was diagnosed in 50%. Neither demographic predictors nor clinical variables predicted the severity of hypoxemia (R²  = 0.23, P = 0.09). While pFEV1 and PSG variables accounted for significant proportion of the overall variance in TSpO₂  < 90 (R²  = 0.53, P < 0.001), pFEV1 was identified as the single best predictor of sleep hypoxemia. A pFEV1 cut-off of 53% indicated a sensitivity of 0.80 and a specificity of 0.87 in predicting sleep hypoxemia.

CONCLUSIONS

pFEV1 is the best predictor of sleep hypoxemia in children with CF and referred for PSG. No demographic or clinical predictors of hypoxemia were identified in this population.

Mucoviscidose : du bon usage des explorations fonctionnelles respiratoires

INTRODUCTION

Neonatal screening for cystic fibrosis (CF) leads to early dedicated specialist care for all patients.

BACKGROUND

Pulmonary function tests (PFT) are mandatory for routine monitoring of CF patients. The aim of this article is to review the current guidelines for PFTs in CF, particularly the type of test, the age and the clinical status of the patient.

VIEWPOINT

The regular use of spirometry is generally accepted. Many other tests are used but their clinical value in the routine follow-up of CF patients remains to be established.

CONCLUSION

Further efforts should be made to evaluate the value of PFTs in CF, particularly in very young children.

Sleep disordered breathing in cystic fibrosis

Cough, sleep fragmentation and oxyhaemoglobin desaturation have all been documented during sleep in patients with cystic fibrosis (CF). It has been proposed that repeated episodes of nocturnal hypoxia act as a stimulus for the development of pulmonary hypertension and right ventricular failure, a complication that is associated with a poor prognosis. In addition, sleep disturbance from these events could lead to poor daytime function and quality of life. This review provides a detailed description of the mechanisms underlying sleep disordered breathing in this population, what is known regarding its effects upon daytime function and current treatment options. Most importantly, we review what is needed from future research in this challenging area of care in patients with CF.

Predictability of oxygen desaturation during sleep in patients with cystic fibrosis : clinical, spirometric, and exercise parameters

BACKGROUND

The purpose of this study was to determine how common sleep-related desaturation with preserved awake resting pulse oximetric saturation (SpO(2)) was in a large cohort of adult cystic fibrosis (CF) patients with variable degrees of pulmonary disease. We then determined whether nocturnal desaturation could reliably be predicted from standard clinical and exercise parameters.

METHODS

Seventy CF patients participated in the study (mean [SD] age, 27.3 [8.7] years; women, 54%; percent predicted FEV(1) [%predFEV(1)], 55.7% [23.9%]). Nocturnal, resting, and exercise SpO(2) were measured. Nocturnal oximetry was measured in the patient's home. Maximal oxygen capacity (Vo(2)max) was determined from a graded exercise test on a stationary bicycle ergometer. The Shwachman-Kulczycki (S-K) illness severity score was calculated incorporating categories of functional capacity, physical examination, nutrition, and chest radiograph.

RESULTS

Multivariate analysis reported significant differences (p < 0.0001) between pulmonary disease severity and overall distribution of nocturnal SpO(2), with the main difference being for patients with severe pulmonary disease (%predFEV(1) of < 50%) compared to patients with mild or moderate disease in the SpO(2) intervals of 100 to 96% (p < 0.0001) and 90 to 86% (p = 0.0001). Pulmonary function, S-K clinical scores, f1.gif" BORDER="0">O(2)max, and resting and maximal SpO(2) correlated significantly (p < 0.05) with nocturnal SpO(2) levels. Stepwise discriminant analysis identified %predFEV(1) (or S-K scores) and resting SpO(2) as the parameters that could best discriminate patients not likely to experience nocturnal desaturation. Specifically, our equation could predict 91% of cases less likely to nocturnally desaturate, but could only modestly predict those more likely to desaturate (i.e., 26% of cases).

CONCLUSIONS

Spirometric parameters and measurements of awake resting oxygenation are of limited utility in predicting nocturnal desaturation. Nocturnal oximetry should be considered in patients with moderate to severe lung disease even with preserved awake resting SpO(2).

Nocturnal oximetry in infants with cystic fibrosis

AIM

To investigate whether children with cystic fibrosis under 3 years of age have disordered breathing and episodes of oxygen desaturation during sleep.

METHODS

We studied 19 infants (9 boys and 10 girls) with cystic fibrosis, mean age 13.1 months (range 3-36 months) and 20 age and sex matched healthy subjects. Patients and controls underwent an overnight polysomnographic study and respiratory function testing on the following morning.

RESULTS

Seven patients with ongoing respiratory tract inflammation had disordered breathing and episodes of oxygen desaturation during sleep. Pulse oximetry showed a significantly lower mean oxygen saturation (SaO(2)) and a higher percentage of total sleep time spent with SaO(2) less than 93% in symptomatic children than in controls.

CONCLUSION

Results suggest that infants and young children with cystic fibrosis and mild airways inflammation (rhinitis, cough, red throat) have episodes of oxygen desaturation during sleep.

Tolerance, pharmacokinetics and efficacy of once daily amikacin for treatment of Pseudomonas aeruginosa pulmonary exacerbations in cystic fibrosis patients

Twenty cystic fibrosis patients aged 1.8-22 years (mean +/- SD: 9.6 +/- 4.8 years) with Pseudomonas aeruginosa pulmonary exacerbations were treated with amikacin (AM) (35 mg/kg/day in one daily 30 min infusion) associated with either ceftazidime (200 mg/kg/day in 3 i.v. injections) (n = 19) or imipenem (n = 1) at the same dose. Glomerular and tubular functions (creatinine clearance, 24-h proteinuria, beta 2 microglobulinuria, lysozymuria) and audiometry remained within normal ranges from day 0 to day 14. A peak concentration of AM of 83 +/- 19 mg/l and a trough concentration of 0.8 +/- 0.5 mg/l were observed in blood while AM levels in sputum were above the minimal inhibitory concentration 50 from 30 min to 16 h. No serum accumulation of AM was observed during the treatment. From day 0 to day 14, the following changes were observed: weight/height ratio: 96%-100% (P < 0.001); daily energy intake: 111%-128% of RDA (P < 0.001); prealbumin: 195-290 mg/l (P < 0.001); forced vital capacity (FVC): 66%-81% (P < 0.01); forced expiratory volume in 1 s: 60%-75% (P < 0.01); forced expiratory flow between 25% and 75% of FVC: 42%-56% (P < 0.01); nocturnal SaO2 also improved significantly; cardiac rate decreased from 89 +/- 18/min to 76 +/- 16/min (P < 0.001); respiratory rate decreased from 31 +/- 15/min to 26 +/- 10/min (P < 0.05); inflammatory parameters (white blood cells, polymorphonuclear cells, erythrocyte sedimentation rate) also improved.

CONCLUSION

Once daily amikacin administration associated with ceftazidime is well tolerated for the treatment of Pseudomonas aeruginosa pulmonary exacerbations in cystic fibrosis patients. Serum peak levels and diffusion in sputum are higher than with a conventional schedule.

Obstructive lung disease and sleep

There is a significant interaction between obstructive lung disease and sleep--sleep is associated with clinical deterioration in obstructive lung disease, and vice versa. Knowledge of the pathophysiology of deterioration in obstructive lung disease during sleep is essential to the understanding of the management of this problem. Recent information has helped to clarify this pathophysiology and has led to more aggressive treatment for deterioration of obstructive lung disease during sleep. Whether this newer and more aggressive treatment strategy improves survival or morbidity in these conditions is a challenge for future research.