Update on research using the impedance
threshold device (ITD) technology for treating
a variety of clinical conditions relevant to
space flight
Victor A. Convertino, PhD
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Disclaimer: The opinions or assertions contained herein are the private views of the author and are not to be construed as official or as
reflecting the views of the Department of the Army or the Department of Defense
What’s the Problem?
Cardiac Arrest
• ~165,000 out-of-hospital cardiac arrests
annually
• ~ 5% to 10% survival to discharge
Orthostatic Instability or Intolerance (Fainting)
• > 500,000 civilians
• 40%-50% of astronauts
• > 10,000 annual cases of syncope in military
Hemorrhagic Shock due to Trauma
• ~40% of civilian deaths
• ~85% of ‘potentially survivable’ deaths on
the battlefield
Central Hypovolemia & Hypotension
Objectives
 Discuss how cardiac and respiratory
interactions impact perfusion
 Describe how inspiratory resistance can
improve circulation and tissue perfusion
 Describe how application of inspiratory
resistance is providing clinical benefits
Moreno AH, Burchell AR, van der Woude R, Burke JH. Respiratory
regulation of splanchnic and systemic venous return.
Am J Physiol 213:455-465, 1967.
Inspiration
Crew of Mission STS-40
Spacelab Life Sciences-1
Buckey, JC, Gaffney FA, Lane LD, Levine BD, Watenpaugh DE, Wright SJ,
Yancy CW, Meyer DM, Blomqvist CG: Central venous pressure in space.
J Appl Physiol 81:19-25, 1996
LVIDD
LVIDD (cm)
5.5
5.0
4.5
4.0
Preflight
Supine
Inflight
14
12
10
8
6
4
2
0
CVP (cm H2O)
CVP
Videbaek R, Norsk P: Atrial distension in humans during microgravity
induced by parabolic flight. J Appl Physiol 83:1862-1866, 1997
Videbaek R, Norsk P: Atrial distension in humans during microgravity
induced by parabolic flight. J Appl Physiol 83:1862-1866, 1997
1G
μG
8
6
*
*
4
2
*
0
-2
-4
-6
CVP
mmHg
LAD
cm
ITP
mmHg
Cardio-Pulmonary Interaction
- Intrathoracic Pressure (vacuum)
⇒
⇑ Preload (Cardiac Filling)
Treatment for
Cardiac Arrest
Decompression Phase
• Small vacuum (negative
pressure) forms in the chest
relative to atmospheric pressure
and draws blood back into the
chest and heart.
•  preload leads to  cardiac
output.
Lurie KG, Coffeen PR, Shultz JJ, McKnite SH, Detloff BS: Improving active
compression-decompression cardiopulmonary resuscitation with an
inspiratory impedance valve. Circulation 91:1629-1632, 1995
Impedance Threshold Device (ITD)
Decompression
Phase
Air
Flow
Ventilation Port
Silicone Diaphragm
Resistance Valve
Patient Port
More Negative
ITP
In Patient
Baseline Hemodynamics
Convertino VA, Ratliff DA, Ryan KL, Cooke WH, Doerr DF, Ludwig DA,
Muniz GW, Britton DL, Clah SD, Fernald KB, Ruiz AF, Idris AH, Lurie KG:
Effects of inspiratory impedance on the carotid-cardiac baroreflex
response in humans. Clin Auton Res 14:240-248, 2004
Convertino VA, Ratliff DA, Ryan KL, Doerr DF, Ludwig DA, Muniz GW, Britton
DL, Clah SD, Fernald KB, Ruiz AF, Idris AH, Lurie KG: Hemodynamics
associated with breathing through an inspiratory impedance threshold
device in human volunteers. Crit Care Med 32(Suppl):S381-S386, 2004
Sham ITD
Active ITD
125
120
115
110
105
100
†
140
130
120
110
100
90
80
†
Cardiac Output, liters/min
150
130
Stroke Volume, ml
Systolic Blood Pressure, mmHg
N = 20
10
9
8
7
6
†
FDA-Cleared
ITD Circulatory Enhancer
Aufderheide TP, Pirrallo RG, Provo TA, Lurie KG. Clinical evaluation of an
inspiratory impedance threshold device during standard cardiopulmonary
resuscitation in patients with out-of-hospital cardiac arrest.
Circulation 33:734-740, 2005
Effects of ITD on Cardiac Arrest Outcomes
Sham ITD (n = 56)
50
Active ITD (n = 49)
*
Percent
40
*
30
*
20
10
0
1-h Survival
ICU Admission
24-h Survival
Device/Drug
Class
Recommendation
Impedance Threshold
Device
IIa
Vest CPR
IIb
Epinephrine
IIb
Amiodarone
IIb
Vasopressin
Indeterminate
Lidocaine
Indeterminate
Atropine
Indeterminate
Critical Care Medicine 32:S345-S351, 2004
American Heart Association
(AHA)
Impact on BLS (CPR) Training
Airway, Breathing, Circulation (ABC)
Circulation, Airway, Breathing (CAB)
First ‘ITD’ Baby
Name: Serenity
DOB: July 11, 2009
(CPR + ITD on face mask + AED) + cooling + ICU care
Index Case
1987
Saved by a
Household Plunger
San Francisco
General Hospital
ResQTrial: CPR Methods Compared
Standard CPR (S-CPR)
ACD CPR + ITD (ACD+ITD)
Survival to Hospital Discharge with
Favorable Neurologic Outcome
10
8.9%
Percent
8
6
5.8%
*53% improvement
P = 0.019
4
N=813
N=840
2
0
S-CPR ACD+ITD
CPR
Orthostatic Hypotension
Orthostatic Intolerance
In Astronauts
Convertino VA, Ratliff DA, Crissey J, Doerr DF, Idris AH, Lurie KG: Effects
of inspiratory impedance on hemodynamic responses to a squat-stand
test: implications for treatment of orthostatic hypotension.
Eur J Appl Physiol 94:392-399, 2005
Orthostatic Challenge
Squat-Stand Test
Total Peripheral Resistance % Δ
Response to Squat-Stand
100
90
80
70
60
50
Squat
Stand
Orthostatic Hypotension
Arterial Pressure =
Heart Rate
X
Stroke Volume
X
Peripheral Resistance
Convertino VA, Ratliff DA, Crissey J, Doerr DF, Idris AH, Lurie KG: Effects
of inspiratory impedance on hemodynamic responses to a squat-stand
test: implications for treatment of orthostatic hypotension.
Eur J Appl Physiol 94:392-399, 2005
Responses to Squat-Stand
STROKE VOLUME
CARDIAC OUTPUT
%Δ
10
8
6
4
2
0
-2
-4
-6
-8
-10
-12
-14
P = 0.002
MEAN BLOOD PRESSURE
Δ mmHg
%Δ
35
P = 0.041
10
30
P = 0.032
0
25
20
-10
15
-20
10
-30
5
0
Sham
ITD
-40
Sham
ITD
Sham
ITD
Convertino VA, Ratliff DA, Crissey J, Doerr DF, Idris AH, Lurie KG: Effects
of inspiratory impedance on hemodynamic responses to a squat-stand
test: implications for treatment of orthostatic hypotension.
Eur J Appl Physiol 94:392-399, 2005
Subject Perceived Rating (SPR)
P = 0.03
Sham ITD
Active ITD
2
SPR
1
10 sec
1 min
Time
Cooke WH, Lurie KG, Rohrer MJ, Convertino VA: Human autonomic and
cerebrovascular responses to inspiratory impedance.
J Trauma 60:1275-1283, 2006
Transcranial Doppler
Cerebral Blood Flow
Mean CBF Velocity, cm/sec
Cooke WH, Lurie KG, Rohrer MJ, Convertino VA: Human autonomic and
cerebrovascular responses to inspiratory impedance.
J Trauma 60:1275-1283, 2006
80
70
60
50
40
30
On ITD
0
100
Off ITD
200
Time, sec
300
400
Convertino VA, Cooke WH, Lurie KG: Inspiratory resistance as a potential
treatment for orthostatic intolerance and hemorrhagic shock.
Aviat Space Environ Med 76:319-325, 2005
Interaction between Intrathoracic Pressure
and Intracranial Pressure
ITD on
ITD off
Use of the ITPR to Improve Cerebral Perfusion
Pressure in Patients with Brain Injury
Intracranial Pressure (n = 9 patients)
40
ICP (mm Hg)
35
30
25
20
15
10
5
0
Baseline
ITD
Mean ↓ ICP = 24%
Tissue Perfusion =
Arterial Blood Pressure
minus
Venous Blood Pressure
Cerebral Perfusion =
Arterial Blood Pressure
minus
Cerebral Blood Pressure
Sublingual Microscopy of a
Septic Pig with 40% Hemorrhage
Improved Tissue Perfusion
Control
ITD
ConvertinoAVA, Ryan KL, Rickards CA, Cooke WH, Idris AH,
Metzger A, Holcomb JB, Adams BD, Lurie KG. Inspiratory
resistance maintains arterial pressure during central
hypovolemia: implications for treatment of patients with severe
hemorrhage. Crit Care Med 35:1145-1152, 2007
Human Model of Hemorrhage
Stroke Volume, ml
100
90
80
70
60
50
40
0
20
40
60
LBNP, mmHg
80
Convertino VA, Ryan KL, Rickards CA, Cooke WH, Idris AH,
Metzger A, Holcomb JB, Adams BD, Lurie KG. Inspiratory
resistance maintains arterial pressure during central
hypovolemia: implications for treatment of patients with severe
hemorrhage. Crit Care Med 35:1145-1152, 2007
Kaplan-Meier Analysis
Tolerance, %
100
75
50
Sham ITD
Active ITD
25
0
0
490
980
1470
1960
Cumulative Blood Loss Index
2450
Treatment for Clinical
Hypotension
Chronic Fatigue Syndrome Patient
An Evaluation of an Impedance Threshold Device to Improve
Hemodynamic Function During Orthostatic Rehabilitation in
Burn Patients
CoTCCC Recommendations
5 August 2009
• “the ITD (ResQPOD) is good for CPR, but has not yet been
shown to be of benefit in trauma patients, especially those
with non-compressible hemorrhage.”
• “Several CoTCCC members noted that the ITD may prove to
be beneficial if the appropriate studies are performed,
especially in . . . patients with hemorrhagic shock . . . “
Optimizing the Respiratory Pump in the
Treatment of Hypotensive Patients with
Hemorrhage and Trauma
Pre ITD
Active ITD
Systolic Blood Pressure,
mmHg
120
†
†
†
100
† P < 0.001
Diastolic Blood Pressure,
mmHg
80
†
†
†
50
†
†
†
40
60
80
Pulse Pressure,
mmHg
30
40
60
40
20
0
All Patients Hemorrhage
Trauma
20
20
10
0
0
All Patients Hemorrhage
Trauma
All Patients Hemorrhage
Trauma
Optimizing the Respiratory Pump in the
Treatment of Hypotensive Patients with
Hemorrhage and Trauma
Secondary Outcomes
• Average tolerance was 1.0 on a scale of 0 (no
difficulty) to 4 (unable to tolerate)
• Duration of use 22.5 minutes (range 3 t0 50 min)
• 213 of 255 (84%) felt ‘better’
• No adverse events recorded
Damage Control Resuscitation?
1st Case Report of a ‘Save’ in Iraq
Keith, Ted, Terry:
Just a quick note about a "save" today.
Actually used it twice –1st time for GSW head with CPR (sadly did not make it)
2nd case : Soldier with GSW to pelvis, came in shock with IABP of 36/16, HCT of
8, Base Def of 26. Had trouble with CVL access so no blood or IVF x 13 mins; so
gave epi, vaso, atropine via ETT. Still no change. Placed (ITD) and got a
palpable pressure (70+ by IABP).
Finally got lines, 16+ units of blood (6 whole) and damage control surgery. Now
off OR table in stabilized condition!
Again, thanks for your support!
LTC Bruce Adams, MC, USA
Chief of Emergency Medicine and Primary Care 228th Combat Support Hospital
OIF Theater Consultant for Emergency Medicine FOB Diamondback, APO AE
09334 Operation Iraqi Freedom
Optimizing the Respiratory Pump
with Inspiratory Resistance
Summary
• Targets primary mechanism(s)
• Non-invasive and nonpharmacological
• Small cube (size; wt < 150 g) and
inexpensive
• It’s simple!
Optimizing the Respiratory Pump
with with Inspiratory Resistance
Summary of Potential Benefits
• Improves survival from cardiac arrest.
• Protects against hypotension
(particularly secondary to
hypovolemia).
• May delay the onset of hemorrhagic
shock.
“. . . modern medicine is
built on teamwork between
physicians, scientists, and
engineers.”
Dr. Gary Seick, Ph.D.
Physiologist, Mayo Clinic
2009 APS President
V.A. Convertino, K.G. Lurie, D.F. Doerr, A.H. Idris
Space Technology Hall of Fame Induction
Colorado Springs, Colorado – April 10, 2008
“Just give me tomorrow”