What is pharyngeal critical pressure?

Pharyngeal critical pressure was derived from the relationship between maximal inspiratory flow and nasal pressure, Pcrit representing the extrapolated pressure at zero flow. Upper airway resistance (Rus) was determined as the reciprocal of the slope (DeltaPn/DeltaVImax cm H2O/L/s) in the regression equation.

What is P crit?

The passive critical closing pressure (Pcrit) technique is the gold standard for measuring upper-airway collapsibility during sleep.

How do you measure Pcrit?

Methods: Pcrit was determined through the use of a noninvasive positive/negative pressure (CPAP/CPNP) ventilator(with independent intellectual property rights) during stageⅡ of non-rapid eye movement sleep. For the direct measurement, Pcrit was the pressure below which the upper airway occluded.

What is considered the diagnostic hallmark of upper airway resistance syndrome?

Diurnal sleepiness remains the main diagnostic criteria, which is often confounded with tiredness in women. UARS patients may also report insomnia and symptoms that closely resemble those of the functional somatic syndromes.

What is high loop gain?

A high loop gain promotes recurrent apnoeas as a response to an initial disturbances, such as a sigh, because it is over compensated, while a low loop gain dampens subsequent oscillations in breathing.

What is loop gain sleep apnea?

Loop gain is an engineering method used to measure the stability of the negative feedback chemoreflex control system. The overall loop gain of the ventilatory system reflects the ratio of the ventilatory response to the disturbance that elicited the response (LG = ventilatory response/ventilatory disturbance).

What is upper airway restriction?

Upper airway resistance syndrome (UARS) happens when the soft tissue in your throat relaxes and doesn’t allow proper airflow while you sleep. It’s similar to obstructive sleep apnea (OSA) but not as severe. Some experts classify UARS as a condition that falls somewhere between snoring and sleep apnea.

What is respiratory loop gain?

How does sleep apnea measure loop?

Loop gain was calculated by dividing ‘the response’ (the overshoot in ventilation after CPAP pressure was restored) by ‘the stimulus’ (the difference between ventilation during the induced hypopnoea and the calculated zero ventilation) which the authors used as a surrogate for the physiological stimuli to ventilation.

What is plant gain?

Plant gain is represented by the effect of a ventilatory response on arterial oxygen and carbon dioxide tensions. If a patient has low dead space, a low metabolic rate, a low functional residual capacity, or a high PaCO2, the effect of ventilatory changes is more marked, resulting in a higher plant gain.