Otto Schoch, PD Dr.

Leitender Arzt

Pneumologie und Zentrum für Schlafmedizin Kantonsspital St.Gallen

Obesity-Hypoventilation and Sleep-Apnea

• WHO Grad I = BMI 30-35 kg/m2

• WHO Grad II = BMI 35-40 kg/m2

• WHO Grad III = BMI >40 kg/m2

Definition Obesity

Stunkard: obese > Silhouette 6

Obesity 2012

• Major ‚public health‘ Problem• Since1980 > Adipositas has dobbeled:

more CV Diseases, Diabetes, Arthrosis, Carcinoma

• 5. frequent cause of death world wide• Risks increase with BMI• Energy imbalance between calories

consumed and calories expended

WHO facts sheet 5/ 2012

Prevalence of BMI >30 kg/m2: <1% to >25%Switzerland 2010: 14%

OSAS patients KSSG (1756): 51%European Sleep Apnea Database (5103): 50.7%(OSAS KSSG >35 kg/m2: 25%)

Otto SchochKantonsspital St.Gallen

Otto SchochKantonsspital St.Gallen

AJRCCM 2012; 185: 241-3

Am J Respir Crit Care Med Vol 179. pp 320–327, 2009

Weight and AHI: Study from Finland mild OSAS, AHI 5-15/h

81 of 630 referrals weight reduction: if > -15 kg: 85% cured !

Sutherland K et al. Thorax 2011;66:797-803

©2011 by BMJ Publishing Group Ltd and British Thoracic Society

Surface reconstructions (CT scans) before and after weight loss

(A) head and neck region

(B) the upper airway.

-19 kg Gewicht (18% KG) + 5.1 cm3 Volumen Pharynx AHI: 55.9 /h auf 15.1 /h.

> Korrektur der Apnoen> CO2 Anfall reduziert

Sullivan CE, Berthon-Jones M, Issa F, Eves L.

Obstructive Sleep Apnea: CPAP

Keeps upper airway openConstant pressure during breath cycle

http://www.nejm.org/doi/full/10.1056/NEJMicm1212352?query=TOC

CPAP for OSAS:Results KSSG

• Adherence at 10y related to OSAS severity and symptoms (ESS)

• BMI does not perdict adherence

(n=1756)unpublished

CPAP for OSAS: Adherence

• Psychological factors: Stepwise approach• Type of mask, mask fit, face masks• Technical: Humidification• Expiratory pressure release• Support interventions, eg Telemedicine• Regular follow-up checks, technical

• Effectivity: Pulse oximetry, CO2

Obesity Hypoventilation OHSHypoventilation =

Wach-PaCO2 > 6 kPa (>45mmHg)

• OHS = BMI > 30kg/m2 + Hypoventilation• No pulmonary or neuromuscular disease• Increase in prevalence with increase in BMI• BMI >50 kg/m2 = > 50% OHS• Prodromal stage: Nocturnal Hypoventilation

Amanda Piper, Ronald Grunstein: AJCCM 2011,183: 292-8

AJCCM 2011,183: 292-8; Respirology 2012, 17: 402–411

J Appl Physiol 2010,108: 199–205,

AJCCM 2011,183: 292-8

OHS

Eucapnic Obesity

Thorax 2009; 64: 719–25

Expiratory Flow Limitation and intrinsic PEEP. CPAP abolishes PEEPi and reduces neural respiratory drive

Ventilatory drive (VD) in OHS

• VD in increased in obesity vs normal weight• No correlation of VD with BMI• OHS: hypercapnic & hypoxic VD markedly

reduced (wake)• Reduction parallels HCO3- elevation• Sleep deprivation: reduced ventilatory response

to hypercapnia• 2 weeks of CPAP improve VD• Acetazolamide increases VD

Respirology (2012) 17, 402–411

Respir Care 2010;55(11):1442–1448

BMI Terzilen: 30-36, 36-42, 42-60 kg/m2

HCO3 Terzilen:26-31, 31-37, 37-44 mmol/L HCO3-

Mit / ohne Acetazolamid(Diamox)

Ventilatory drive in OHS

Anesthesiology 2012; 117:188 –205

Anesthesiology 2012; 117:188 –205

Anesthesiology 2012; 117:188 –205

Prognosis of OHS

Screening for OHS OSAS patients at diagnosis

BMI 30-40 kg/m2: 10% OHS

BMI 40-50 kg/m2: 20% OHS

BMI >50 kg/m2: 50% OHS

Pulsoxy <92%

aBGA in OHS: PaO2 <70 mm Hg (10kPa)

HCO3 >27 mEq/L: Sensitivity 92%, specificity 50%

continuous transcutaneous CO2 Monitoring

very sensitive > Prodromal stage of OHS (eg in REM)

Positive Airway Pressure for OHS

• CPAP: High pressure levels to overcome ‚upper airway resistance‘

• Oxymetry in the first night: 30-50% of OHS still at SpO2 <90%

• Adherence is a better predictor of paCO2 decrease than CPAP vs bilevel NIV J Clin Sleep Med 2006;2:57–62

NIV for OHS: Technical issues• CPAP vs NIV• Supplemental Oxygen• NIV Mode: S / ST / T• How to define optimal frequency ?• How to define optimal EPAP level /

Automatic EPAP?• Role of Average Volume Assured PS with

IPAP range (Storre, Chest 2006)

> Need for measuring PSG / PG / ptCO2

CPAP or bilevel NIV ?1 Radomized controlled trial

Thorax 2008;63:395–401.

CPAP or bilevel NIV ?Thorax 2008;63:395–401.

Supplemental O2 for OHS

• „Double-edged sword“

• Risk of CO2 increase with O2

• MV decreases considerably with 100% O2

• Assess reason for low O2

– Pulmonary hypertension, CTEPH, COPD– Heart failure

• Monitor effect on CO2 and HCO3

• Consider Acetazolamide if HCO3 highCHEST / 139 / 5 / MAY, 2011: 975 f

Long term results: NIV for OHS

CHEST 2010; 138(1):84–90

OHS with and without supplemental O2

CHEST 2010; 138(1):84–90

S-Mode / ST-Mode low back-up / ST-Mode high back-up ?

A: Central Apnea Hypopnea Index (N/hour); B: Mixed Apnea Hypopnea Index

Chest 2012, e-pub

A- Central hypopnea under NPPV in “S/T” mode with high BURR (RR: 20/min). Note disappearance of thoraco-abdominal movements during the event and resumption of flow with resumption of respiratory movements; ventilator switches to BURR and continues to pressurise, inducing small spikes on the flow curve. Drop in SpO2 ensues. Chest 2012, e-pub

B- Obstructive hypopnea under NPPV in “S/T” mode with low BURR (RR: 11/min.). Flow decreases drastically in spite of persistent pressurisations by the ventilator, which has switched to BURR. Thoracic and abdominal movements show phase opposition and a gradual increase in inspiratory efforts until airflow resumes. The event induces a drop in SpO2. Chest 2012, e-pub

C- Mixed apnea under NPPV in “Spontaneous mode”. Two consecutive events associated with drops in SpO2. Total interruption of airflow, with cessation of thoraco- abdominal movements during the initial part of the event (central component), followed by resumption of thoraco-abdominal movements with phase opposition (obstructive component). No pressurisation occurs during the event because ventilator is in “S” mode. Chest 2012, e-pub

Treating chronic OHS: how I do it

• Always start with nasal or oronasal CPAP• Re-assess after 1 month of treatment:

adherence and night-time oximetry

• If night-SpO2 <92%: aBGA, LuFu, 6MWT, PG/PSG under CPAP with ptCO2, Echo

• Refractory OHS: Switch to NIV, Consider Acetazolamide

• PAH suspected: Right heart catheter, antikoagulation, (specific treatment?)

Haemodynamic effects of non-invasive ventilation in patients with OHS

• 30 OHS patients • Echo: 43% systolic pulmonary hypertension• 6 months NIV• sPAP from 58±11 to 44±12 mmHg (p<0.05)• 6MWT from 350±110 to 426±78m (p<0.01)

Respirology. 2012 Nov;17(8):1269-74