Number Of Desaturations Research Articles

Quantification of sleep disordered breathing by computerized analysis of oximetry, heart rate and snoring

Intermittent snoring and cyclic oscillations of heart rate and oxyhaemoglobin saturation (Sao2) are characteristic features of the obstructive sleep apnoea syndrome (OSAS). Thus, overnight recordings of laryngeal sounds and heart rate by a portable device (MESAM) and of Sao2 by oximetry are applicable to screen outpatients for the presence of OSAS. Computerized analysis for time intervals of constant heart rate and intervals between snoring sounds is used by MESAM to quantify respiratory disturbances during sleep. Rapid increases in Sao2 during the postapnoeic hyperventilation period together with the number of desaturations are used by a new software for quantitative analysis of oximetry. To elucidate reliability of results from automatically scored MESAM and oximetry recordings, we compared the four computer calculated respiratory disturbance indices from heart rate (RDIH), snoring (RDIS), resaturations (RDIR) and desaturations (RDID) with the apnoea plus hypopnoea index (AHI) from simultaneously performed polysomnography. The study population consisted of 53 snorers with an AHI of 19.0 +/- 2.6 (median +/- SEM; range 0.7-87.8). Whereas both RDI's from MESAM correlated rather weakly with the AHI from polysomnography (RDIH: r = 0.32, p less than 0.05; RDIS: r = 0.33, p less than 0.05), this correlation was much better for the RDI's from oximetry (RDIR: r = 0.951, RDID: r = 0.93; p much less than 0.0001). Accepting a plus/minus 30 percent difference from the AHI, the RDIR classified 77% of patients correctly, the RDID 62%, the RDIS 32% and the RDIH 23%. In conclusion, results from computerized analysis of oximetry for desaturations and rapid resaturations correlate more closely with polysomnography than those from automatic scoring of MESAM recordings.

Termination off Central Sleep Apnea Episodes by Upper Airway Stimulation Using Intermittent Positive Pressure Ventilation

A 52-year-old man presented with pure central sleep apnea syndrome that failed to respond to nasal continuous positive airway pressure (NCPAP) therapy. Intermittent positive pressure stimulation via a nasal mask was instituted using a portable positive pressure ventilator. We found marked reduction in the respiratory disturbance index, number of desaturations, and the number of arousals with this mode of therapy.

Hypoxaemia during Postoperative Recovery using Continuous Pulse Oximetry

Continuous pulse oximetry monitoring was used to determine the incidence of hypoxaemia (arterial oxygen saturation less than or equal to 90%) occurring in the first hour of postoperative recovery. Of 107 patients studied, hypoxaemia was recorded in 80%. Twenty-eight (26%) of these patients had saturations below 80%. The average frequency (i.e., the number of desaturations per patient) and the total duration of these desaturations was 7.7 desaturations and 182 seconds respectively. Intermittent measurements taken preoperatively and at 5 and 30 minutes postoperatively revealed hypoxaemia in 2%, 4% and 6% of patients respectively. In 39 patients who received oxygen therapy throughout the monitoring period, 64% experienced hypoxaemia within the first 15 minutes of recovery as opposed to only 18% in the final 15 minutes monitoring period. Of the factors assessed, only patients with a body mass index greater than 25 had an increased risk of hypoxaemia (P less than 0.01). Four patients required active intervention and ventilatory assistance. We conclude that postoperative hypoxaemia is a particularly common occurrence even in patients otherwise considered healthy. Hence, pulse oximetry should be employed routinely during recovery. Where possible, monitoring should be performed continuously for at least 45 minutes.

Treatment of obstructive sleep apnea with continuous nasal airflow.

Although nasal continuous positive airway pressure (CPAP) is effective therapy for obstructive sleep apnea (OSA), it requires a customfitted nasal appliance and large cumbersome tubing. We therefore designed and tested a new device (NFLOW) to deliver airflow to the nose of patients with OSA. We studied 13 patients the first night without treatment and the following night with NFLOW. The degree of sleep apnea was assessed by the number of desaturations per hour of sleep and the average maximum desaturation per episode. Treatment with NFLOW significantly decreased all parameters (P<0.01) in 9 patients (69%) who tolerated treatment flow rates above 30 LPM. REM sleep time significantly increased with NFLOW use, however, other sleep stage times were not significantly altered. Obstructive apneas ceased in all but 2 of these patients with treatment. Four patients did not tolerate flow rates above 35 LPM and did not improve. We conclude that NFLOW treatment significantly decreases the number of oxyhemoglobin desaturations and improves oxyhemoglobin saturation in patients with OSA who tolerate the procedure.

Arterial Oxygen Desaturation during Sleep in Children with Asthma and Its Relation to Airway Obstruction and Ventilatory Drive

The possibility that arterial oxygen saturation (SaO2) decreases during sleep in children with chronic bronchial asthma was investigated. The relationship between decreases in sleep SaO2 and airflow obstruction and ventilatory drives, as characterized by ventilatory and inspiratory muscle activity responses to hypoxia and hypercapnia was also examined. Sixteen asthmatics on suboptimal bronchodilator therapy and ten healthy children were studied. Both maximum decrease in SaO2 and number of desaturations (decrease in SaO2 greater than or equal to 4%) per hour during sleep were greater in the asthmatics than in the control subjects. Both maximum decrease in SaO2 and number of desaturations per hour asleep were correlated with change in FEV1 and FEF25%-75% over the sleep period. Changes in SaO2 were not related to awake measurements of ventilatory drive. Eight of the asthmatics also were studied when on a more optimal medication regimen. On this program they had less airflow obstruction before and after sleep, and the number and extent of decreases in SaO2 were not different from those of the control subjects. We conclude: (1) decreases in SaO2 occurred during sleep in suboptimally treated asthmatic children; (2) SaO2 changes during sleep were related to the amount of air-flow obstruction that developed during sleep; (3) SaO2 changes during sleep were not related to ventilatory drive measured during wakefulness; and (4) a good therapeutic regimen eliminated abnormal amounts of sleep hypoxemia by improving airflow limitation. However, as the results of this study indicate, when their pulmonary status is unstable, asthmatic children may develop clinically significant hypoxemia during sleep.