Increased peripheral chemosensitivity via dopaminergic manipulation promotes respiratory instability in lambs

Edwards, Bradley A.; Sands, Scott A.; Skuza, Elizabeth M.; Stockx, Elaine Maria; Brodecky, Vojta; Wilkinson, Marcia; Berger, Philip J.

doi:10.1016/j.resp.2008.09.003

Cited by 30 publications

(36 citation statements)

References 76 publications

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“…Our study did not have a similar period. The magnitude of feedback control, or "loop gain," is a major determinant of CSA, and with an increase in loop gain there is a resulting increase in CSA index (15)(16)(17). Periodic breathing decreases with acclimatization to moderate altitude.…”

Section: Discussionmentioning

confidence: 99%

Effects of Positive Airway Pressure on Patients with Obstructive Sleep Apnea during Acute Ascent to Altitude

et al. 2015

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Rationale: In acute ascent to altitude, untreated obstructive sleep apnea (OSA) is often replaced with central sleep apnea (CSA). In patients with obstructive sleep apnea who travel to altitude, it is unknown whether their home positive airway pressure (PAP) settings are sufficient to treat their obstructive sleep apnea, or altitude-associated central sleep apnea.Methods: Ten participants with positive airway pressure-treated obstructive sleep apnea, who reside at 1,320 m altitude, underwent polysomnography on their home positive airway pressure settings at 1,320 m and at a simulated altitude of 2,750 m in a hypobaric chamber. Six of the participants were subsequently studied without positive airway pressure at 2,750 m.Measurements and Main Results: At 1,320 m, all participants' sleep apnea was controlled with positive airway pressure on home settings; at 2,750, no participants' sleep apnea was controlled. At higher altitude, the apnea-hypopnea index was higher (11 vs. 2 events/h; P , 0.01), mostly due to hypopneas (10.5 vs. 2 events/h; P , 0.01). Mean oxygen saturations were lower (88 vs. 93%; P , 0.01) and total sleep time was diminished (349 vs. 393 min; P = 0.03). Four of six participants without positive airway pressure at 2,750 m required supplemental oxygen to prevent sustained oxygen saturation (as determined by pulse oximetry) less than 80%. Positive airway pressure also was associated with reduced central sleep apnea (0 vs. 1; P = 0.03), improved sleep time (358 vs. 292 min; P = 0.06), and improved sleep efficiency (78 vs. 63%; P = 0.04).Conclusions: Acute altitude exposure in patients with obstructive sleep apnea treated with positive airway pressure is associated with hypoxemia, decreased sleep time, and increased frequency of hypopneas compared with baseline altitude. Application of positive airway pressure at altitude is associated with decreased central sleep apnea and increased sleep efficiency.

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Section: Discussionmentioning

confidence: 99%

Effects of Positive Airway Pressure on Patients with Obstructive Sleep Apnea during Acute Ascent to Altitude

et al. 2015

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“…Duty ratio (DR) was calculated as a surrogate for loop gain (Edwards et al, 2008;Sands et al, 2011), using methods described elsewhere (Andrews et al, 2012). Briefly, apneas were scored as a drop in the peak signal excursion by ≥90% of pre-event baseline using the oro-nasal sensor for ≥10 s with associated absent inspiratory effort throughout the entire period of absent airflow, and hypopneas scored as a peak signal excursion drop by ≥30% of pre-event baseline using nasal pressure for ≥10 s with a ≥3% oxygen desaturation from pre-event baseline, unless the apneas or hypopneas occurred as a segment of continuous periodic breathing, in which case the entire duration of the respiratory event was taken.…”

Section: Data Analysis and Statistical Measuresmentioning

confidence: 99%

“…Briefly, apneas were scored as a drop in the peak signal excursion by ≥90% of pre-event baseline using the oro-nasal sensor for ≥10 s with associated absent inspiratory effort throughout the entire period of absent airflow, and hypopneas scored as a peak signal excursion drop by ≥30% of pre-event baseline using nasal pressure for ≥10 s with a ≥3% oxygen desaturation from pre-event baseline, unless the apneas or hypopneas occurred as a segment of continuous periodic breathing, in which case the entire duration of the respiratory event was taken. DR was calculated as mean time (in seconds) of hyperpnea/(hyperpnea + apnea) (Edwards et al, 2008;Andrews et al, 2012).…”

Section: Data Analysis and Statistical Measuresmentioning

confidence: 99%

Bed rest and hypoxic exposure affect sleep architecture and breathing stability

et al. 2017

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“…Central apnea length (CAL) in sec, ventilatory 14 The duty ratio has been assessed experimentally in lambs by Edwards et al in 2008 by using a modified mathematical linearization model of the oscillatory breathing pattern of periodic breathing and the apneic threshold where an increase in loop gain results in a decrease in DR. 15 The same "duty ratio" [DR] method has also been used by Sands et al…”

Section: Respiratory Cycle Measurementmentioning

confidence: 99%

Ventilatory Cycle Measurements and Loop Gain in Central Apnea in Mining Drivers Exposed to Intermittent Altitude

Castro

Liendo²,

Ortiz

et al. 2017

Journal of Clinical Sleep Medicine

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Study Objectives: By measuring the apnea length, ventilatory phase, respiratory cycle length, and loop gain, we can further characterize the central apneas of high altitude (CAHA). Methods: Sixty-three drivers of all-terrain vehicles, working in a Peruvian mine located at 2,020 meters above sea level (MASL), were evaluated. A respiratory polygraph was performed in the first night they slept at high altitude. None of the subjects were exposed to oxygen during the test or acetazolamide in the preceding days of the test. Results: Sixty-three respiratory polygraphs were performed, and 59 were considered for analysis. Forty-six (78%) were normal, 6 (10%) had OSA, and 7 (12%) had CAHA. Key data from subjects include: residing altitude: 341 ± 828 MASL, Lake Louise scoring: 0.4 ± 0.8, Epworth score: 3.4 ± 2.7, apneahypopnea index: 35.7 ± 19.3, CA index: 13.4 ± 14.2, CA length: 14.4 ± 3.6 sec, ventilatory length: 13.5 ± 2.9 sec, cycle length: 26.5 ± 4.0 sec, ventilatory length/CA length ratio 0.9 ± 0.3 and circulatory delay 13.3 ± 2.9 sec. Duty ratio media [ventilatory duration/cycle duration] was 0.522 ± 0 0.128 [0.308-0.700] and loop gain was calculated from the duty ratio utilizing this formula: LG = 2π / [(2πDR-sin(2πDR)]. All subjects have a high loop gain media 2.415 ± 1.761 [1. 175-6.260]. Multiple correlations were established with loop gain values, but the only significant correlation detected was between central apnea index and loop gain. Conclusions: Twelve percent of the studied population had CAHA. Measurements of respiratory cycle in workers with CAHA are more similar to idiopathic central apneas rather than Hunter-Cheyne-Stokes respiration. Also, there was a high degree of correlation between severity of central apnea and the degree of loop gain. The abnormal breathing patterns in those subjects could affect the sleep quality and potentially increase the risk for work accidents. Keywords: driver, sleep, central apnea, high altitude, loop gain Citation: Rey de Castro J, Liendo A, Ortiz O, Rosales-Mayor E, Liendo C. Ventilatory cycle measurements and loop gain in central apnea in mining drivers exposed to intermittent altitude.

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Increased peripheral chemosensitivity via dopaminergic manipulation promotes respiratory instability in lambs

Cited by 30 publications

References 76 publications

Effects of Positive Airway Pressure on Patients with Obstructive Sleep Apnea during Acute Ascent to Altitude

Effects of Positive Airway Pressure on Patients with Obstructive Sleep Apnea during Acute Ascent to Altitude

Bed rest and hypoxic exposure affect sleep architecture and breathing stability

Ventilatory Cycle Measurements and Loop Gain in Central Apnea in Mining Drivers Exposed to Intermittent Altitude

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