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Sleep-related breathing disorders - Pathofysiology respiration during sleep

Q: What is periodic breathing, and how does it relate to high altitude?

Periodic breathing occurs when there are alternating periods of deep and shallow breaths. Common at high altitudes due to lower oxygen levels. Observed on Mount Everest at 5400 m . Mentioned by Lahiri in Resp Physiol 1983 .

Q: How is snoring with periodic obstruction identified in the given chart?

Nasal pressure inspiration : Shows variations, indicating flow changes. Signs of flow limitation and snoring : Observed in initial phase. No flow limitation, no snoring : Detected in later phase. Chest excursions inspiration : Consistent wave patterns.

Q: How does lung volume affect desaturation during apnea?

Smaller lung volumes result in faster desaturation during apnea. Breath hold at Total Lung Capacity (TLC) : 88 seconds, desaturation rate of 0.28%/sec. Breath hold at Functional Residual Capacity (FRC) : 42 seconds, desaturation rate of 0.54%/sec. Breath hold at Residual Volume (RV) : 37 seconds, desaturation rate of 0.82%/sec.

46 important questions on Sleep-related breathing disorders - Pathofysiology respiration during sleep

What is periodic breathing, and how does it relate to high altitude?

Periodic breathing occurs when there are alternating periods of deep and shallow breaths.
Common at high altitudes due to lower oxygen levels.
Observed on Mount Everest at 5400 m.
Mentioned by Lahiri in Resp Physiol 1983.

What happens to ventilation during different sleep stages?

Reduced in NREM sleep
Further diminishes during phasic REM sleep
Reduction of intercostal muscle activity

What conditions lead to hypoventilation during REM sleep?

Impaired diaphragmatic function
Diaphragm paralysis
Obesity
COPD

How is snoring with periodic obstruction identified in the given chart?

Nasal pressure inspiration: Shows variations, indicating flow changes.
Signs of flow limitation and snoring: Observed in initial phase.
No flow limitation, no snoring: Detected in later phase.
Chest excursions inspiration: Consistent wave patterns.

What might cause periodic breathing?

- Resonance in chemoreflex-feedback loop

What factors contribute to increased controller gain in OSA?

Hyperventilation causes PaCO₂ to drop below the apnoea threshold.
Low chemoreflex activity during apnoea reduces activation of dilator muscles:
- Sleep
- Obesity, especially in supine position

How does lung volume affect desaturation during apnea?

Smaller lung volumes result in faster desaturation during apnea.
Breath hold at Total Lung Capacity (TLC): 88 seconds, desaturation rate of 0.28%/sec.
Breath hold at Functional Residual Capacity (FRC): 42 seconds, desaturation rate of 0.54%/sec.
Breath hold at Residual Volume (RV): 37 seconds, desaturation rate of 0.82%/sec.

How does increased plant gain affect oscillation in OSA?

Increased oscillation amplitude in PaO₂ at given ventilation oscillation.
Small lung volume (obesity, supine) leads to fast desaturation during apnoea or hypopnoea.

Explain Obstructive Sleep Apnea (OSA) in the context of periodic breathing.

Example of periodic breathing
Periodic reduction of chemoreflex activity
Periodic reduction of genioglossus activity
Obstructive apnoeas due to upper airway collapse (obesity, lying supine)

What is reduced wakefulness drive's role in OSA?

- The stabilizing influence of wakefulness drive is diminished.

What characterizes periodic breathing in OSA due to increased loop gain?

Periodic Breathing: Alternates between hyperventilation and reduced phasic activity.
Nasal Pressure: Shows distinct patterns of fluctuation.
Rib Cage Movement: Exhibits significant variation.
Desaturation: SaO₂ (%) decreases indicating oxygen drops.

What is Cheyne-Stokes respiration and how can it be affected by CO₂ inhalation according to Lorenzi-Filho et al.?

Cheyne-Stokes respiration involves periods of breathing irregularity.
It often occurs in chronic heart failure patients during sleep.
CO₂ inhalation can abolish this breathing pattern.
The cycle time is approximately 1 minute.

What are the characteristics and effects of high-altitude sleep apnoea?

Hypoxaemia leads to hyperventilation.
Results in fall of PaCO₂ below apnoea threshold.
Causes increased controller gain.
Common in those with increased hypoxic ventilatory response (Lahiri, 1983).
Cycle time is approximately 20 seconds.

What does the CO₂ response curve show regarding apnoeic threshold and PETO₂ levels?

CO₂ response curve illustrates ventilation changes at different PCO₂ levels.
Apnoeic threshold observed near PCO₂ of 40 mmHg.
PETO₂ levels at 40 mmHg and 80 mmHg influence ventilation.
Higher PETO₂ results in increased ventilation slope.

What happens when loop gain equals 1 in a control system?

Achieving loop gain of 1 is labeled impossible.
System shows oscillations in PaCO₂, indicating instability.
Disturbance and response affect cycle time and steady state.
Components include chemoreflex, ventilation, and pulmonary gas exchange.

What does "Loop gain < 1: dampened oscillation" indicate in respiratory control?

Loop gain < 1 indicates stable, dampened oscillation.
Cycle time and real-time response to disturbances depicted.
PaCO₂ levels oscillate between 30-50 mmHg.
G_C: chemoreflex, G_P: pulmonary gas exchange.
Shows interaction between disturbances, response, and ventilation.

What does loop gain represent in the context of chemoreflex and ventilation control?

Loop gain is calculated as controller gain (\(GC\)) multiplied by plant gain (\(GP\)).
Chemoreflex refers to \(GC\).
Pulmonary gas exchange refers to \(GP\).
Disturbance involves \(PAO2\) and \(PACO2\) changes.
Response is the ventilation adjustment.

What is the response of a linear system shown in the diagram?

Input: \(A1\)
Output: \(A2\)
System: Transfers input to output
Gain: Calculated as \( \frac{A2}{A1} \)

What is periodic breathing by resonance in the chemoreflex-feedback loop?

Chemical Disturbance: PAO₂ and PACO₂ levels change.
Controller (Gₐ): Chemoreflex senses disturbance.
Ventilation Adjustment: Increases or decreases.
Response by Plant (Gₚ): Pulmonary gas exchange.
Cycle Continues: Feedback adjusts to maintain balance.

What is the circulation time from the lung to the carotid body?

Average circulation time is approximately 8 seconds.
Pathway includes the lung and heart.
Relevant studies: Jain et al., Clin Sci 1972; Coulter et al., J Physiol 1980; Kobayashi et al., Appl Hum Sci 1996; Younes, J Appl Physiol 2008.

What are the functions and sensitivities of peripheral chemoreceptors located in the carotid bodies?

Location: Carotid bodies
Sensitive to:

1. Hypoxaemia (low PaO₂)

Hypercapnia (high PaCO₂)
Acidosis (low pHa)

Afferent signal: Via nerve IX to nucleus tractus solitarii
Response:

1. Deeper breathing

Vagal bradycardia (only during apnea)
Sympathetic vasoconstriction

What does the graph from Lahiri et al., Respiration Physiology 1983 show regarding high-altitude periodic breathing?

Inhalation of ~3% CO₂ reduces high-altitude periodic breathing.
Ventilation rate (V_T) displays reduced oscillations with CO₂.
Oxygen saturation (SaO₂) stabilizes with CO₂ addition.
Time in seconds indicated for measurement.

What does the study by Lahiri et al. (1983) demonstrate about high-altitude periodic breathing?

Topic: High-altitude periodic breathing
Study Location: Mount Everest, 5400 m
Technique Used: Adding 100% O₂
Effect Observed: Reduced periodic breathing
Measurements Included:
- Tidal volume (Vᵀ)
- Arterial O₂ saturation (SaO₂)
- Electrooculogram (EOG)
- Electrocardiogram (ECG)
- PIO₂ levels

What are the characteristics of nasal pressure and PCO₂ over the 10-minute period?

P nasal (mmHg): Cycles between breathing patterns, with clear pauses.
PCO₂ (mmHg): Fairly stable, without large fluctuations.
Both maintain consistent patterns throughout the 10-minute period.

What factors contribute to the activation of upper airway dilator muscles?

Wakefulness: Leads to tonic activity.
Mechanoreceptors: Triggered by negative intraluminal pressure.
Chemoreceptors: Influence respiratory drive.
Central Pattern Generator: Affects phasic (inspiration).
N. Laryngeus Sup. and N. XII: Contribute to hypoglossal motor nucleus activity.
M. Genioglossus: Affected by the hypoglossal motor nucleus.

Describe the changes in chest movement and SaO₂ over the recorded time.

Chest movement: Alternates between rhythmic breathing and pauses, indicating central apnea.
SaO₂ (%): Remains above 90%, relatively stable but occasionally dips slightly.

What does the MRI study indicate about upper airway collapse in obese adolescents?

Demonstrates upper airway collapse during central sleep apnoeas.
Observes obese adolescents.
Graphs show changes in:

1. Cross-sectional area (mm²).

Mask pressure (cm H₂O).
Biowave displacement (A.U.).

Identify the overall trends in pulse and pulse rate (PR) during the monitoring session.

Pulse: Shows high variability with consistent beats and occasional increased intensity.
PR (min⁻¹): Fluctuates moderately, with a general trend of mild rise and fall.

What factors contribute to keeping the upper airway open?

Dilator muscles: Help maintain patency.
Tracheal stretch: Assists in keeping airway open.

What changes are observed in genioglossal activity during REM sleep compared to NREM sleep?

Decreased genioglossal activity is noted during REM sleep.
Measurement detected using EMG_GGTA (percentage of maximum) and GG_RAW (Volts):
- Higher activity in NREM
- Lower activity in REM.

What factors lead to upper airway closure?

Pressure of soft tissues: Can obstruct airflow.
Negative intraluminal pressure (inspiration): Promotes airway collapse.

What are the characteristics of the upper airway during sleep according to Morell and Badr, J Appl Physiol 1998?

Upper airway shows narrowing at the end of inspiration.
Dilatation occurs at the beginning of expiration.
Changes occur in coordination with sleep cycles.
Graph plots CSA (%) vs. Time (s), highlighting these phases.

What anatomical structures are depicted in the diagram of the retropalatal airway?

Anterior View: Uvula, Soft Palate, Epiglottis
Posterior View: Posterior Pharyngeal Wall
Tracheal Inlet location identified
Labeled Sections: A (Diagram), B (Image)
Source: Morell and Badr, J Appl Physiol 1998

What does the graph show about periodic breathing in obstructive sleep apnea?

Nasal Pressure:
- Shows fluctuations with peaks and troughs.
Rib Cage Movement:
- Mirrors nasal pressure with periodic rises and falls.
- Includes red sections indicating significant deviations.
SaO₂ (%):
- Demonstrates periodic dips.
- Time scale: 1-minute intervals.

What does the graph indicate about REM sleep-related desaturation in unilateral diaphragm paralysis?

REM sleep is associated with desaturation.
Oxygen saturation (SpO₂) drops during REM periods.
Desaturation is evident when lying on the healthy side.
Associated with unilateral diaphragm paralysis.
Study by Baltzan et al., 2012.

What are the components of the respiratory centres in the brainstem?

Pons:
- Kölliker-Fuse
- Parabrachial nucleus (lateral and medial)
- Ventrolateral pons
Medulla oblongata:
- RTN/pFRG
- BotC
- PreBotC
- VRG (rVRG, cVRG)
Additional Structures:
- nu.V and nu.VII
- DRG
- nu. ambiguus
- n.IX, X

What components are involved in the control of respiration according to the diagram?

Motor cortical & other cortical outputs
- Influence respiratory centers.
Pontomedullary rhythm & pattern generators
- Coordinate respiration patterns.
Motoneurones
- Relay signals to respiratory muscles.
Reflexes
- Integrate sensory feedback.
Respiratory muscles
- Execute breathing movements.
Valve & Pump
- Regulate airflow dynamics.

What details are included in the slide about the course on pathophysiology of respiration during sleep?

Title: Pathophysiology of Respiration During Sleep
Course: International Sleep Medicine Course 2022
Presented by: Prof. Joost van den Aardweg
Department: Respiratory Medicine, Amsterdam UMC
Country: Netherlands

What are the differences in breathing patterns during NREM and REM sleep?

NREM: Regular breathing, ventilation ~10% lower than wakefulness.
REM: Irregular pattern, ventilation 8-15% lower, rapid superficial respiration.

What are the factors related to the collapse of a paralyzed upper airway in normal and OSAS awake conditions?

Normal:
- No spontaneous collapse occurs.
- Collapse only if intraluminal pressure < -5 cmH₂O.
OSAS (awake):
- Spontaneous collapse factors:
- Fat
- Smaller bony compartment
- Neck perfusion?
- Posture

How does the contribution of respiratory muscles differ between NREM and REM sleep?

NREM: Increased contribution of intercostal muscles.
REM: Strongly decreased contribution of intercostal muscles.

What does the graph show about REM-sleep related desaturation in severe COPD?

Severe COPD patients experience significant oxygen desaturation during REM sleep.
SaO₂ levels drop below 90%.
Desaturations are frequent during REM periods.
Data from Marrone et al., Int J COPD 2006.

Describe the control systems and their effects on breathing during NREM and REM sleep.

NREM: Decreased 'wakefulness drive', increased tendency for periodic breathing.
REM: More pronounced reduction of chemoreflex sensitivity, lower apnoea threshold.

What does the graph reveal about REM-sleep in obesity-hypoventilation syndrome?

Shows REM-related desaturation
SaO2 (%) decreases during REM
REM period spans 30 minutes
SaO2 levels drop below 90%

What is depicted in the data on rib cage movements during phasic REM sleep?

Inhibition During REM: The rib cage movements are inhibited during phasic REM sleep.
Electrooculogram (EOG): Displays eye movement.
Rib-Cage Signal: Shows reduced movement.
Abdomen Signal: Continues regular movement.
Reference: Millman, J Applied Physiol 1988.

What potential conflicts of interest does the speaker have?

Speaker disclosed potential conflicts of interest.
No conflicts of interest identified.
Part of the International Sleep Medicine Course 2022.

The question on the page originate from the summary of the following study material:

Sleep Medicine Textbook | 9781119789017 | Claudio Basseti, et al

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