3936599.ppt
- 1. An introduction to Intrathoracic Pressure Regulation Therapy 49-2057-000, 01
- 3. What is Intrathoracic Pressure Regulation? Intrathoracic Pressure Regulation (IPR) is a therapy that enhances negative pressure in the chest and has been shown in studies to effectively improve circulation of blood to the brain and other vital organs.1
- 4. Pressure and Natural Physiology
- 5. Intrathoracic Pressure The body continually regulates the circulation of blood by using positive and negative pressures inside the thoracic cavity to maintain equilibrium.
- 6. Positive vs. Negative Pressure PUSHES air away Inhibits blood return Principle behind CPAP therapy The thoracic cavity is like a bellows… Creates a vacuum PULLS fluid and air in Principle behind IPR therapy Negative Pressure Positive Pressure
- 7. Normal Physiology Conversely when you inhale (inspiration), you create a slight negative pressure, which… Pulls air into lungs Returns blood to the chest Lowers ICP When you exhale (exhalation), you create a slight positive pressure, which… Forces air out Inhibits blood return to the heart Increases intracranial pressure (ICP)
- 8. Moreno et al. Respiratory regulation of splanchnic and systemic venous return. Am J Physiol 1967;213:455-465. Effect of Intrathoracic Pressure on Blood Flow Intrathoracic Pressure (cmH2O) Blood Flow, Abdominal Vena Cava (l/min-1) Respiration and circulation are closely linked. Dating back to 1967, we have known there is an inverse relationship between intrathoracic pressure and blood flow. As intrathoracic pressure decreases... blood flow increases.
- 9. 2 Seconds per Division 5 -10 0 mmHg 55 mmHg 75 35 -5 cmH2O 5 -15 55 mmHg 75 35 Aortic Pressure Intracranial Pressure Intrathoracic Pressure Cerebral Perfusion Pressure Pressures with No Intervention Intrathoracic Pressure and ICP Linked Convertino et al. Resp Care 2011;56:846-857. Animal Model with 40% Bleed - No Intervention
- 11. Normal Physiology - Compensation The body regulates pressures as part of its normal compensatory response. Under stress, such as when exercising, one breathes harder, faster, deeper; this… • Enhances negative pressure in the thoracic cavity • Lowers intracranial pressure (ICP) to improve blood flow to the brain
- 12. However, sometimes a body is unable to adequately compensate. Example: Shock 1. Heart rate increases in an effort to maintain sufficient blood flow 2. Intrathoracic pressure is modulated in an effort to increase perfusion 3. Eventually, body is unable to adequately compensate and blood pressure drops Result: Insufficient perfusion to protect the brain and other vital organs. Body in Trouble
- 13. Intrathoracic Pressure Regulation (IPR)
- 14. Positive Pressure Results: 1. Drives fluid out of the lungs 2. Decreases preload 3. Decreases cardiac output 4. Decreases blood pressure Continuous positive airway pressure (CPAP) and positive pressure ventilation (PPV) are common and well accepted therapies for pulmonary edema.
- 15. IPR = Negative Pressure IPR leverages negative intrathoracic pressure to enhance perfusion; studies1 have shown that it... Enhances negative intrathoracic pressure2 (i.e. increases the vacuum in the chest), which... ① Draws more blood back to the heart3,7 (i.e. increases preload), which leads to increased cardiac output and blood pressure and ① Decreases intracranial pressure (ICP)4,5,6 which makes it easier to get blood into and out of the brain (i.e. increases cerebral perfusion)
- 16. Intrathoracic Pressure Regulation (IPR) Normal Breathing IPR Therapy Enhances Negative Pressure (Increased cardiac output) (Decreased cardiac output)
- 18. IPR Therapy is simply using the “other side of pressure,” enhancing negative pressure to improve perfusion. Studies1 show that IPR Therapy: Enhances negative intrathoracic pressure2 Increases preload3 Increases cardiac output3 Increases blood pressure7 Lowers ICP4,5 Results in more forward cerebral blood flow, better perfusion of the brain.6 Impact of IPR ResQGARD ITD ResQPOD ITD
- 19. Intrathoracic Pressure Regulation Therapy helping the body help itself Intrathoracic Pressure
- 20. Impedance Threshold Devices (ITDs) Deliver IPR ResQGARD ITD ResQPOD ITD Studies Show1 How it Works Enhances circulation in patients undergoing CPR during cardiac arrest (profound shock) Prevents the influx of air during chest wall recoil to enhance negative intrathoracic pressure Enhances circulation in spontaneously breathing patients with low blood pressure (shock) Creates a slight amount of therapeutic resistance during inhalation to enhance negative intrathoracic pressure
- 21. The Evidence
- 22. 2 Seconds per Division Aortic Pressure Intracranial Pressure Intrathoracic Pressure Cerebral Perfusion Pressure No IPR 5 -10 0 mmHg 55 mmHg 75 35 -5 cm H2O 5 -15 55 mmHg 75 35 With IPR Impact of IPR on Pressures Convertino et al. Resp Care 2011;56:846-857. Animal Model with 40% Bleed
- 23. Time (secs) Mean CBF Velocity (cm/sec) IPR On IPR Off 400 300 200 100 0 30 40 50 60 70 80 Cooke et al. Human autonomic and cerebrovascular responses to inspiratory impedance. J Trauma 2006;60:1275-1283. Cerebral Blood Flow ON / OFF Effect of IPR
- 25. References 1. The generally cleared indication for the ResQPOD and ResQGARD ITDs available for sale in the United States is for a temporary increase in blood circulation during emergency care, hospital, clinical, and home use. Research is ongoing in the United States (US) to evaluate the longer-term benefits of the ResQPOD and ResQGARD for other specific indications. The studies listed here are not intended to imply specific outcomes-based claims not yet cleared by the US FDA. 2. Lurie KG, Zielinski T, McNite S, Aufderheid T, Voelckel W. Use of an inspiratory impedance valve improves neurologically intact survival in a porcine model of ventricular fibrillation. Circulation 2002; 105(1):124-129. 3. Lurie, KG, Voelckel WG, Zielinski T, et al. Improving standard cardiolpulmonary resuscitation with an inspiratory impedance threshold valve in a porcine model of cardiac arrest. Anesth Analg 2001;93:649- 55. 4. Aufderheide TP, Alexander C, Lick C, et al. from laboratory science to 6 emergency medical services systems: new understanding of the physiology of cardiopulmonary resuscitation increases survival rates after cardiac arrest. Crit Care Med 2008;36(11):S397-S404. 5. Alexander C, Yannopoulos D, Aufderheide T, et al. Dual mechanism of blood flow augmentation to the brain using an impedance threshold device in a pediatric model of cardiac arrest. Circulation 2007; 116(16):II-433. 6. Lurie KG, Mulligan KA, McNite S, Detloff B, Lindstrom P, Lindner KH. Optimizing standard cardiopulmonary resuscitation with an inspiratory impedance threshold valve. Chest 1998;113(4):1084- 1090. 7. Pirrallo RG, Aufderheide TP, Provo TA, Lurie KG. Effect of an inspiratory impedance threshold device on hemodynamics during conventional manual cardiopulmonary resuscitation. Resuscitation 2005;66:13-20.
Editor's Notes
- #6: As part of normal physiology our body regulates pressures in the chest all the time to keep the body in equilibrium. By regulating pressures inside the chest our body regulates the interactions that occur between three critical body systems: the respiratory, circulatory and nervous systems.
- #8: The body uses POSTIVE and NEGATIVE pressures to influence air and fluid movement within the body every minute of every day. Let’s begin with an example of the BODY AT REST. As we exhale, our diaphragm moves up and the chest wall moves in. This creates a slight positive pressure inside the chest that forces air out of the lungs and blood away from the chest. It also increases ICP. When we inhale, the opposite occurs; our diaphragm moves down and the chest wall moves out. This creates a slight vacuum (negative pressure) inside the chest that draws air into the lungs and lowers ICP. This positive pressure also makes it harder to return blood to the chest.
- #9: This physiology is not new. This study, published in 1967, shows the relationship between intrathoracic pressure and blood flow through the abdominal vena cava. You can see that when you enhance the negative pressure (vacuum) in the chest during inspiration, the result is a rise in blood flow; and as the intrathoracic pressure then rises, blood flow is diminished.
- #10: Data from Convertino’s study show the relationship between intrathoracic pressure, intracranial pressure and aortic and cerebral perfusion pressures.
- #12: The body regulates intrathoracic pressure as part of normal physiology to compensate when it becomes stressed. For example, when we exert ourselves through strenuous exercise, there are increased metabolic demands. The body helps itself by increasing the heart rate, and enhancing the positive and negative pressures by breathing harder and deeper. These compensatory moves increase tidal volume and cardiac output, and lower ICP during inspiration, making it easier to get blood to the brain. The body makes similar adjustments to compensate when it is going into shock.
- #13: When the compensatory mechanisms fail, as in the case of shock, the blood pressure begins to fall.
- #15: Regulating Intrathoracic pressure to treat patients is not new. With positive pressure ventilation we are able to drive fluids out of the lungs and decrease preload, cardiac output and blood pressure. What happens if we regulate negative Intrathoracic pressure?
- #16: Intrathoracic Pressure Regulation, or IPR, enhances negative Intrathoracic pressure to treat patients in states of low blood flow. Contrary to CPAP, enhancing the vacuum in the chest helps to increase preload, cardiac output and blood pressure. In addition, IPR lowers intracranial pressure by influencing the fluid filled sinuses that run along the spinal column that allow us to transmit pressure in the chest to the head. Think about it…have you ever had a bear hug by someone and felt the increased pressure in our head? That’s an example of chest pressure being transmitted to the head.
- #17: Now let’s talk about how IPR Therapy can help the body when it’s in trouble. IPR Therapy enhances negative intrathoracic pressure, resulting in enhanced blood flow.
- #18: ITDs help to further enhance the vacuum in the chest. For the circulatory system, this vacuum increases preload and thus cardiac output. For the nervous system, this vacuum lowers ICP, making it easier to get blood into and out the head, thus improving cerebral blood flow. The net result is improved perfusion to vital organs.
- #19: Intrathoracic Pressure Regulation (or IPR) Therapy is delivered today via impedance threshold devices or ITDs. These devices enhance negative intrathoracic pressure to help patients in states of low blood flow like shock and sudden cardiac arrest. Studies show that IPR Therapy increases preload, cardiac output and blood pressure; decreases ICP and allows for more forward blood flow to the brain.
- #21: Today, IPR is delivered through ITDs. In patients undergoing CPR, an ITD can be applied to the ventilation circuit breathing circuit. It selectively prevents air from being drawn in during chest wall recoil and wiping out the vacuum. For patients in shock, an ITD can be applied with a facemask to create slight resistance to breathing and in turn enhances negative intrathoracic pressure.
- #22: So how do we know IPR works?
- #23: This animal study by Convertino et al shows the correlation between negative intrathoracic pressure, intracranial pressure, aortic pressure and cerebral blood flow. When negative Intrathoracic pressure is enhanced, aortic pressure increases, ICP is lowered, and cerebral perfusion is enhanced.
- #24: This study does a nice job of showing the effect that IPR has on cerebral blood flow. Here you see that cerebral blood flow velocity rises as soon as IPR is applied, and then decreases when it is removed. Now let’s look at how IPR works in shock and cardiac arrest and assess the clinical data that support it in those applications.