Challenging Cases in Pediatric Polysomnography

Fauziya Hassan, MBBS, MS

Assistant Professor

Pediatric Pulmonary and Sleep

Conflict of Interest

• None pertaining to this topic

• Will be using some slides from Respironics

Outline

• Physiology of CO2 monitoring

• Challenges of neuromuscular disorders

• Central hypoventilation

End Tidal CO2 monitoring

• In a normal lung CO2 rapidly diffuses across the capillary alveolar membrane with ventilation and perfusion well matched

• EtCO2 reading is the PCO2 equivalent to airway CO2 concentration at the end of exhalation which approximates arterial PCO2 (slightly higher than by 4 mm Hg)

End Tidal CO2 Errors

• Increase in dead space ventilation-underestimates arterial PCO2

• Incomplete exhalation before next mechanical breath-small airways obstruction

• Smaller tidal volumes among children

• Leaks

• Increase in physiologic dead space

- low cardiac output states e.g. PE, blood loss

- hypothermia

- hyperventilation

Conditions for End Tidal CO2 monitoring

• Neuromuscular diseases

Duchenne muscular dystrophy

myotonic dystrophy

SMA

diaphragmatic paralysis

cerebral palsy

poliomyelitis

congenital muscle diseases

PSG in Infant

5 year old boy born full term was transferred from OSH for evaluation of rapid weight gain and sleep apnea

Sleep study within the first year showed minor issues may need adenotonsillectomy

Healthy until age 4 years. He gained 66 pounds in 10 months. Hyperphagia noted. Loud snoring with gasping and snorting arousals

History Of Present Illness

PSG- obstructive sleep apnea and T&A done in October 2011. Slight improvement after T&A; he still snores and has pauses in breathing

PSG with ETCO2 monitoring (2012), demonstrates severe OSA (AHI of 30.8) Minimum oxygen saturation was 61%

He also has hypoventilation with the sleep study, ETCO2 more than 50 mmHg (414.2 minutes out of total sleep time of 615.5 minutes)

History Of Present Illness

Titration study (July 2012) - did not respond well to CPAP. Switched to bi-level support with some improvement with pressure of 14/8 cm of water . However, severe treatment emergent central apnea rapidly developed. Further adjustment in the pressure made no difference

Initial BiPAP setting 20/15 cm of water and with oxygen 3 liters per minute. Three weeks later, his sleep doctor lower his BiPAP setting to 14/8 with oxygen supplementation of 2 liters per minute

History of Present Illness

Sleep Study UMHS

Venous blood gas - PCO2 of 62 mm Hg and pH of 7.21

Split night study (TCO2) monitoring. Baseline portion of the study - severe OSA and hypoventilation with paradoxical respiration, worse during REM sleep.

Initial baseline oxygen saturation was low (82-84%) and oxygen via nasal cannula was added at 0.5 LPM.

TCO2 values prior to oxygen supplementation was between 52-63 mm Hg and increased to 67-71 mm Hg. The ETCO2 spot checks at 53 mm Hg and TCO2 values at 67 mm Hg

Modes of Non-Invasive Ventilation

Non –invasive positive pressure ventilation

BiPAP (bi-level positive airway pressure)

BiPAP with ST mode (spontaneous-timed)

BiPAP with T mode (timed)

BiPAP with PC mode (pressure control)

Average Volume Assured Pressure Support (AVAPS) ® with ST mode

AVAPS with PC mode

Trigger to IPAP

BiPAP in PC vs. ST mode

Triggered

breaths

BiPAP with Inability to Trigger IPAP

BiPAP with Inability to Trigger IPAP

BiPAP with ST Mode

BiPAP with ST (Lower Tidal Volume with Spontaneous Breaths)

Next Case

• New patient 49 yr old male OSA, CSA (diagnosed 2000), pulmonary hypertension, hyperlipidemia, central hypoventilation syndrome

• Persistent daytime fatigue and sleepiness despite using backup rate of 18. Excellent compliance noted on ASV. Now has difficulty with maintaining oxygen saturations during day and night time oxygen desaturations to 70s noted

• Excessive daytime fatigue and sleepiness, currently sleeping about 10 to 12 hours every night and also taking Nuvigil 250 milligrams daily and Ritalin 10 milligrams twice daily

Next Case

• He was started on BiPAP with O2, initially, he was on 2 liters of oxygen, which was recently changed to 4 liters per minute

• Currently, on ASV machine with EPAP min 5 cm, max of 12 cm, pressure support 6 -13, maximum pressure of 18 and a backup rate of 18 with Bi-Flex of 2 and 3 liters of oxygen during the day and 4 liters at home

• Last ABG - pCO2 of 72 mm Hg. Last titration (December 2014) with total sleep time of 215 minutes and his apnea-hypopnea index on that study was 3.1, baseline oxygen saturation of 92.8% (nadir O2 of 78%)

• PFT - FEV1 98%, FVC - 90% FEV1/FVC ratio 80% O2 saturation 96% at rest on room air

AVAPS

• AVAPS (Average Volume Assured Pressure Support) is available in

S (spontaneous)

S/T (spontaneous/timed)

PC (pressure control)

T (timed) modes

• Helps maintain the tidal volume by automatically controlling the pressure support by varying the IPAP between the IPAP minimum and IPAP maximum settings

Indications

• Patients with hypoventilation-either central or peripheral –

congenital central hypoventilation syndrome

(CCHS) or acquired hypoventilation

neuromuscular diseases - muscular dystrophy,

spinal muscular atrophy (SMA) amyotrophic

lateral sclerosis (ALS)

restrictive lung disease - neuromuscular scoliosis

• AVAPS is also indicated in patients with COPD and obesity hypoventilation

Confidential Sector, MMMM dd, yyyy, Reference

Target Vt

EPAP

IPAP

IPAP min

IPAP max

Averaged Volume Assured Pressure Support

AVAPS automatically adjusts the pressure support according to

the patient’s needs to maintain an average tidal volume.

AVAPS

Confidential Internal use only

AVAPS automatically adapts pressure support to patient needs to

guarantee an average ventilation

What is AVAPS

?

IPAP Max

IPAP Min

EPAP

Vte = Vt patient

< 1 cmH2O/min

Target Vt

Averaged Volume Assured Pressure

Support

Next Case

• New patient 49 yr old male OSA, CSA (diagnosed 2000), pulmonary hypertension, hyperlipidemia, central hypoventilation syndrome

• Persistent daytime fatigue and sleepiness despite using backup rate of 18. Excellent compliance noted on ASV. Now has difficulty with maintaining oxygen saturations during day and night time oxygen desaturations to 70s noted

• Excessive daytime fatigue and sleepiness, currently sleeping about 10 to 12 hours every night and also taking Nuvigil 250 milligrams daily and Ritalin 10 milligrams twice daily

Next Case

• He was started on BiPAP with O2, initially, he was on 2 liters of oxygen, which was recently changed to 4 liters per minute

• Currently, on ASV machine with EPAP min 5 cm, max of 12 cm, pressure support 6 -13, maximum pressure of 18 and a backup rate of 18 with Bi-Flex of 2 and 3 liters of oxygen during the day and 4 liters at home

• Last ABG - pCO2 of 72 mm Hg. Last titration (December 2014) with total sleep time of 215 minutes and his apnea-hypopnea index on that study was 3.1, baseline oxygen saturation of 92.8% (nadir O2 of 78%)

• PFT - FEV1 98%, FVC - 90% FEV1/FVC ratio 80% O2 saturation 96% at rest on room air

Thank you