Transcript Slide 1

Understanding the Impact of Obesity
on Breathing and Sleep
Scot Jones, BA, RRT-ACCS, RCP
Is Obesity a Problem?
of adults in the United
States, or 60 million
people, are obese
From CDC.gov
Is Obesity a Problem?
Children
worldwide are obese
From World Health
Organization
Is Obesity a Problem?
of diabetes
of ischemic heart disease
certain cancers
From World Health
Organization
Is Obesity a Problem?
of United States medical
costs may be directly
related to obesity
From CDC.gov
Is Obesity a Problem?
Yes.
A Few Statements
• Poking fun? I think not.
• Respect the person, analyze the behavior.
• Health professionals should have a (basic)
understanding of obesity’s effects on how we
deliver care.
FACT
or
FICTION?
Obese people tend to be lazier
than people who are thinner.
FACT AND FICTION!
Sedentary lifestyle practices do
contribute to obesity, but
there are many people who
are sedentary, but not obese
FACT
or
FICTION?
Obese people eat too much.
FACT AND FICTION!
Overeating does contribute to
obesity, but it is more
complicated than just that
FACT
or
FICTION?
Obese people are
less intelligent
FICTION!
Obvious? Maybe not socially!
FACT
or
FICTION?
Obese people have control
over their weight
FACT AND FICTION!
Weight control is very complex.
Calories In
Weight
Calories Out
Where are we heading?
• Understanding some terminology
• Lung Mechanics
• Comorbidities
– Obesity Hypoventilation Syndrome
• Strategies
– Socioeconomic considerations
– Critical care considerations
• Noninvasive, airway, ventilatory, weaning/extubation
How to Define
Obesity
Methods of Measurement
• Body Mass Index (BMI) - calculation
• Hydrostatic weight
% Body Fat
• Body calipers
Body Mass Index
Body Weight (kg)
Height (m2)
Flaws
•Indirect Measurement
•Doesn’t take muscle into
account
Strengths
•Noninvasive
•Simple and effective
when used in context
BMI – NIH/NHLBI Table
BMI
< 18.5
19-24
25-29
30-34
35-39
40+
Below normal weight
Normal weight
Overweight
Class I Obesity
Class II Obesity
Class III Obesity
National Institutes of Health (NIH), National Heart, Lung, and Blood Institute (NHLBI). The
practical guide: identification, evaluation, and treatment of overweight and obesity in adults.
Bethesda: National Institutes of Health. 2000, NIH publication 00-4084.
Lung Mechanics
and
Obesity
• Diaphragm is pushed
upward
• Weight on chest wall
restricts, and prevents
diaphragmatic
excursion
• Adipose requires
blood/oxygen
• Increased risk of
obstructed upper
airway
Systemic Proinflammatory State
Oversimplified:
Proinflammatory molecules lead to a number of
metabolic and cardiovascular complications
of obesity, which may lead to airway
inflammation (think Asthma)
Related
Diseases and Disorders
Obstructive Sleep Apnea
From Washington.edu
Classifying Severity
Apnea Hypopnea Index
(AHI)
OSA Severity
OSA Score
6-20
Mild
1
21-40
Moderate
2
> 41
Severe
3
Adapted from Gross, JB, Bachenber, KL, and Benumof, JL, et al.
Practice guidelines for the perioperative management of patients
with obstructive sleep apnea. Anesthesiology 2006; 104:1081.
Hypertension
Traffic/
Workplace
Accidents
Insulin
Resistance
OSA
Cardiac
(HF,
Rhythm,
MI)
Stroke
Memory
problems
Obesity and OSA
• 1-SD increase in BMI = 4x increased risk for
OSA (Young, et. Al)
• BMI > 40 = 40-90% prevalence (Rajala, et. Al)
• 10% change in body weight = 30% change in
AHI
BMI
OSA Prevalence
Fat Distribution and OSA
• Male > Female
• Distribution (central pattern around
neck/trunk/abdominal)
Schwartz, et al. Annals of the ATS, Feb 2008
Obesity Hypoventilation Syndrome
Respiratory
Load
Drive &
Strength
Mechanisms of Ventilatory Failure
•Lung and Chest Wall Elastic
Loads
•Lung CL
•Insp Threshold
Respiratory
Drive
&
•Chest Wall
Mechanics
•Supine Position
Load
Strength
•Resistive Loads
•Upper AW Obstruction
•Lower AW Obstruction
•Other Loads
Mechanisms of Ventilatory Failure
•Increased CO2 Production
•Increased Deadspace
•Decreased Drive
•Blunted drive in OHS
•Resp Depression (Meds)
•Sleep Deprivation
Respiratory
•Hypothyroidism
Load
•CNS disease
Drive &
Strength
•Decreased Strength
•Deconditioning and
atrophy from acute illness
•Medications
•Metabolic
Disorders of Ventilatory Failure
Mechanisms
•Myopathic Effects
Apnea/Hypopnea
Event
↑ PaCO2
PaCO2/pH
return to
baseline
 pH
OSA
Renal Compensation
↑ HCO3
Depression of Ventilation
Apnea/Hypopnea
Event
↑ PaCO2
PaCO2/pH
fails to
return
 pH
OHS
Strategic Considerations
Meta-Analysis
• LOS / BMI are directly related statistically
• > BMI may have a “protective effect”
• > LOS may be due to > difficulty in dx and tx,
not mobilizing pt as often
• > LOS = > Mortality (long-term)
BMI and Disease Risk
Sociocultural Question #1
As a Health Professional,
is it your responsibility
to be concerned with a
patient’s weight?
Sociocultural Question #2
As a Health Professional, is it
your responsibility to counsel
patients on their weight
status
(overweight or underweight)
“Sir, You’re Fat.”
A Few Cautions
• Most people are already aware that they are
obese
• Many people are sensitive about their weight
• Most people will not (can not?) make major,
sweeping changes
• Consider your own motives and attitudes
about people who are obese
Dilemmas in Diagnostics
• Diagnostics become increasingly difficult –
everything:
– The X-Ray
– CT Scanning
– Ultrasound
– Access for blood-related lab tests
– Clinical confusion of multiple comorbidities
+
The Airway
Bergler, et al., 1997
The Airway
The Ideal Airway
Airway Strategies
• Assess the physiology
• Proactive use of “difficult airway equipment”
• Consider back-up plan – what will you do if
you cannot intubate?
• Consider NOT using paralytics or heavy
sedation if possible
• Consider trial of noninvasive ventilation
Nutrition
• Actual Body Weight may overestimate (HarrisBenedict Equation)
• Consider Indirect Calorimetry
• Consider in context of failure-to-wean
The Nutrition Balance
• Caloric Restrictions
– Catabolic-induced muscle loss impairs wound
healing
– Weakens diaphragmatic muscles – delays
ventilator weaning
– Moderate restriction may be okay
• Excessive Calories
– Increases production of CO2 which will increase
minute ventilation (tachypnea) -> failed SBT ->
potential delays in weaning
Noninvasive vs. Invasive
• Treat OSA and OHS
• Pre-intubation
– PaO2 higher with NPPV preparation.
Futier, et. Al, Anesthesiology, Vol 114(6), 1354-1363
• Post-extubation
– Support earlier extubation attempts by extubating
directly to NPPV
To Trach or Not to Trach
• Unable to Wean, repeated intubations, longterm needs
• CPAP failure with OSA
• BiPAP failure with OHS
(opportunity for
ventilatory support at night)
To Trach or Not to Trach
• Controlled environment (OR)
• Trach changes
may be a challenge
• Specialized trachs
• Early Tracheostomy
Positioning
• Consider Reverse Trendelenberg (sitting
upward while lying down)
Early Mobility
• Laying in a hospital bed quickly results in
muscle wasting, and it is much more difficult
to get it back once it is gone
• Early mobilization is a key (yes, even if the
patient is in the ICU, and on a vent, and on
high FIO2, and on high PEEP)
• Use of adapted mobility equipment
Ventilation Strategies
• What we know:
– High pressures hurt the lungs
– Large volumes hurt the lungs
– There is a greater incidence of later-onset ARDS in
patients who are obese than there are in leaner
patients (Gong, et al.; Thorax. 2010;65(1):44-50)
Ventilation Strategies
The Big Question:
Appropriate VT should be set by:
a.)
b.)
c.)
d.)
Height
Weight
Waist circumference
Whatever feels right
How do we offset, then, the weight on the chest?
Ventilation Strategies
Answer: Using Applied (or therapeutic) PEEP
Consider starting point of . . .
+8 to +10 cmH2O
+15?
+20?
Ventilator Pressures
Lung Protective Strategy:
Maintain Pplat < 30 cmH2O
Obese Patients:
There can be a battle between maintaining safe
pressures and maintaining adequate ventilation.
Consideration: Watch pressures carefully: Consider
measuring transpulmonary pressures and
maintaining < 35 cmH2O
Weaning Considerations
•
•
•
•
Adequate Support
Provide adequate hemodynamic support
Consider tracheostomy with subsequent wean
Consider specialized unit and systemized
approach
• Future direction of weaning
Medication Considerations
• Pain/Sedation + adipose storage = prolonged
period of recovery
• Significant concern of ventilatory depression
with adequate pain management (loss of
airway!)
• Medication administration by IBW, TBW, or
DW?
Obesity is not just a
comorbidity.
It is a disease.
Clinical Diagnosis is
Complicated
So is recovery.
When the
body is BIG
The lungs are not