Heart lung interaction
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This document discusses the relationship between heart and lung function and the interaction between intrathoracic pressures, lung volumes, and blood flow. It begins by explaining that the cardiovascular and pulmonary systems function to link metabolizing cells to oxygen sources. It then discusses how intrathoracic and intramural pressures impact blood flow through collapsible tubes based on principles of fluid dynamics. Changes in surrounding pressures, such as pleural or pericardial pressure, can impact lung volumes, cardiac preload and afterload, and venous return. Understanding these complex interactions is important for critical care.
Heart lung interaction
- 1. Heart lung interaction 8EDLGXU 5DKDPDQ 6HQLRU 5HVLGHQW &&0 6*3*,06 /XFNQRZ ,QGLD
- 2. “The primary function of the cardiovascular- pulmonary system is to link metabolizing cells with energy sources in the environment” “Mother Nature is the meanest management Guru in terms of cost effectiveness” Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 3. Relatonship between FLOW and PRESSURE P1 intra mural pressure P2 P1> P2 Pressure gradient (∆P) = P1-P2 At a constant ∆P flow depends upon RESISTANCE to that flow Resistance (Poiseuille equation) ⁿ= viscosity of fluid, L= length of tube, r= radius of tube Force driving flow (F) = ∆P/ R Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 4. Relatonship between FLOW and PRESSURE Radius (r) of any collapsible tube depends on distending pressure TRANSMURAL PRESSURE Psur Pim Psur Transmural Pressure = intramural pressure – surrounding pressure (Ptm = Pim – Psur) Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 5. In a collapsible tube if volume is not allowed to change Change in Psur will bring about similar change in Pim so that Ptm will remain unchanged 4 1 10 7 4 1 Ptm = 10-4=6 Ptm = 7-1=6 Volume will remain unchanged only when Ptm remains unchanged Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 6. Analogous scenario if lung volume is not allowed to change, then transpulmonarypressure will not change and relationship between airway pressure and pleural pressure will remain constant muller’s maneuver or valsalva maneuver change in pleural pressure will bring identical change in airway pressure so that lung volume remains constant Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 7. Surround pressure for intrathoracic vascular structures outside the alveoli and their vessels is JUXTACARDIAC PLEURAL PRESSURE which is defined as INTRATHORACIC PRESSURE (ITP) changes in ITP will bring about similar changes in Pim of vascular structures (so that Ptm remains constant) and this change will be measured by device (which measure it relative to Patm) this is easily appreciable in patients with arterial line during coughing (causing increased ITP) increased arterial pressure could be seen on monitor Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 8. another analogy “Ship in the water appearing to rise and fall as it is acted upon by passive waves when viewed from shore. The same ship, however does not change its relationship to water, and as for as the ship is concerned is quiet stable in the sea, and is not forever sinking and rising again” Cardiopulmonary interaction, Pinsky, Cardiopulmonary Critical Care, W.B. Saunders Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 9. What we routinely measure Pim in relation to Patm ITP Pim ITP Arterial Pressure Central venous pressure Ppa/Ppao For Transmural pressure We need Pleural pressure or pericardial pressure Measurement of Pleural pressure or pericardial pressure is difficult and tricky Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 10. For heart Psur is pericardial pressure (Ppc) Ttm = Pim – Ppc Pericardium high extensibility at lowlevel of stress with an abrupt transition to relative inextensibility at higher stress therefore it exerts a restraining effect on volume of heart Physiologic role of normal pericardium Matthew W. Watkins, Martin M. LeWinter, annu. Rev. Med 993;44:171-180 Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 11. When heart is not distended and pericardium is not diseased Ppc = Ppl but Ppc >> Ppl if heart is distended primarycardiac disease or ventricular interdependence) (pericardium exerts restraining effect) pericardium is diseased pericardial fluid or decreased pericardial compliance overdistension of lung or massive pleural effusion or tension pneumothorax compressing heart in cardiac fossa Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 12. All we talked about is mechanical factors but there are other factors which simultaneously and dependently play role Mural smooth muscle ( vascular, cardiac) Neuro-humoral factors effecting these smooth muscles Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 13. Transient effects: mechanical Periodic changes induced by respiratory cycle (phasic effects) or unsustained effects of various respiratory manoeuvres like coughing, straining, recruitment manoeuvre Steady state effects: mechanical and neuro-humoral Impact of sustained alterations of respiratory conditions: PEEP, CPAP, weaning Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 14. Changes In Lung Volume Neuro-humoral interactions Autonomic tone Respiratorysinus arrhythmia (normal autonomic responsiveness) Lung inflation at Vt >15 ml/kg ↓ heart rate by sympathetic withdrawal Reflex vasodilation with lung hyperinflation Humoral factors Sustained hyperinflation induces fluid retention by ↑ plasma norepinephrine and renin and↓ Atrial natriuretic peptide (ANP) Mechanical interactions compression of heart in cardiac fossa by juxtacardiac ITP and Lung Volume ↑PVR (by hyperinflation) Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 15. Primary difference in NPV and PPV Negative pressure ventilation primary change is in pleural pressure which leads to change in airway pressure Positive pressure ventilation primary change is in airway pressure which leads to change in pleural pressure Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 16. Surrounding Pressures of Circulatory System Ppl Ppl Palv Ppc Patm Patm Ppl Ppl Pabd Pabd Patm Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India Patm= 0 Ppl= -2 to -5 Pabd = <5
- 17. PLEURAL PRESSURE Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 18. P-V curve of Lung, Chest wall and Respiratory system Chest wall Lung TLC Vital capacity % 100 Chest wall and Lung ( respiratory system) 75 50 25 FRC RV 0 -20 0 20 Pressure ( cm H2O) Ppl, Pcw, Prs Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 19. Resting Volume of Respiratory system Negative pleural pressure Elastic force of LUNG = Elastic force of CHEST WALL At End Expiration Functional Residual Capacity (FRC) Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 20. Pleural space is only a potential space Pressure is difficult to measure But can be estimated from distal esophageal pressure ( in posterior mediastinum where esophagus lies between two pleural recesses) Pleural pressure is not uniform throughout the pleural space Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 21. Effect of gravity + weight of lung Vertical gradient in Ppl and TTP Dependent alveoli have lesser volume than non dependent alveoli Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 22. This truth remains true when lung volume is increasing Change in Pleural Pressure is NOT UNIFORM When lung is inflating Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 23. Heart and great vessels In cardiac fossa TRAPPED AND COMPRESSED Greater change in Ppl Lateral chest wall moves outward Less change in Ppl Diaphragm most compliant Least change in Ppl Pleural pressure change juxta cardiac > lateral chest wall > diaphragm Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 24. In different pathological states Obesity compliance of lateral chest wall decreases Greater change in Ppl Intra abdominal hypertension compliance of diaphragmatic pleura decreases Greater change in Ppl Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 25. Change = +3 Change = +2 Change = +5 Change = +10 Cardiopulmonary interaction, Pinsky, Cardiopulmonary Critical Care, W.B. Saunders Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 26. Pleural pressure has to be defined accordingly Lung compliance lateral chest wall pleural pressure Hemodynamic juxta cardiac pleural pressure Diaphragmatic work diaphragmatic pleural pressure Eosophageal pressure estimates diaphragmatic pleural pressure Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 27. Relationship between PLEURAL PRESSURE, LUNG VOLUME and AIRWAY PRESSURE Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 28. Relation betweenAlveolar pressure and Pleural pressure ∆ITP / ∆Palv = 1/(1+Ccw/CL ) In healthy subjects, Ccw=CL, during normal tidal volumes ∆ITP / ∆Palv = ½ Half of applied PEEP would be expected to be transmitted to ITP Decrease in CL will decrease the transmission Clinical review: positive end expiratory pressure and cardiac output Thomas Luecke, Palolo Pelosi. Crit Care 2005,9:607-621 Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 29. Relationship between PLEURAL PRESSURE, LUNG VOLUME and AIRWAY PRESSURE in normal and diseased lung ALI control Cardiopulmonary effect of positive pressure ventilation during acute lung injury. Romand JA, Shi W, Pinsky MR. Chest 1995;108:1041-1048 Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 30. Relationship between PLEURAL PRESSURE, LUNG VOLUME and AIRWAY PRESSURE in normal and diseased lung ALI control Cardiopulmonary effect of positive pressure ventilation during acute lung injury. Romand JA, Shi W, Pinsky MR. Chest 1995;108:1041-1048 Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 31. Primary determinant of increases in Pleural Pressure during PPV is change in LUNG VOLUME, not change in airway pressure If tidal volume is kept constant, pleural pressure will increase equally, independent of the mechanical properties of lung Decreased compliance/ higher airway resistance higher Paw required to generate similar tidal volume Presumably pericardial pressure does not increase as much as ITP because increasing lung volume reduces filling of ventricles, decreasing their size inside cardiac fossa It is difficult to estimate changes in pleural pressure or pericardial pressure that will occur in patient as PEEP is increased. Heart lung interactions. Pinsky MR, Textbook of Critical Care, 5th edition, Elsvier Saunders Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 32. Surrounding Pressures of Circulatory System Patm Patm Ptm = Pim - Patm Ppl Ppl Ptm = Pim - Ppl RA LV RV LA Ppl Ppl Ptm = Pim - Ppl Ppl Ppl Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 33. Change in ITP independent of change in lung volume Changes in Ptm will be similar with any change in ITP for all intrathoracic structures No change in RV afterload gradient to flowin Pulmonarycirculation LV preload Except those continuing as extra thoracic structureAorta and great veins Gradient to flow Venous return and cardiac ejection Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 34. VR and ITP Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 35. VR and ITP Increased ITP Increased MSFP increased Pim of RA Increased Resistance to VR Decreased VR Decreased Pim of RA Decreased Ptm of RA Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 36. Trend recording of RA pressure, juxta cardiac Pleural pressure and RA transmural pressure Cardiopulmonary interaction, Pinsky, Cardiopulmonary Critical Care, W.B. Saunders Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 37. LV afterload and ITP Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 38. LV afterload and ITP increase ITP---- increase Pim Aorta Intrathoracic aorta Ptm unchanged ( Ptm= Pim – ITP) Extrathoracic aorta Ptm increased (Ptm=Pim- Patm) sensed by carotid baroreceptors Decreased Pim Intrathoracic aorta Decreased Ptm of intrathoracic aorta LV Ptm required to open A also decreased V Decreased LV wall stress vasodialation Decreased Pim Ptm came to baseline value Decreased LV afterload Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 39. Reflex vasodilatation Reflex vasoconstriction Cardiopulmonary interaction, Pinsky, Cardiopulmonary Critical Care, W.B. Saunders Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 40. Concept of AFTERLOAD Wall tension = Transmural pressure radius of curvature / wall thickness T = Ptm r / h ( Laplace’s Law) Of any given volume, geometrical shape, with smallest radius of curvature is SPHERE Most stable geometrical shape, of any volume Air bubbles acquire spherical shape Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 41. LV ejects blood into Aorta when A opens V A opens when LV Ptm exceeds Aortic Ptm V LV Ptm is generated (isovolumetric contraction) To generate this Ptm, tension is generated in muscle fibre (isometric contraction) This Tension generation requires ATP WORK OF PUMPING Increased ITP Aortic Ptm is decreased AFTERLOAD IS DECREASED STROKE VOLUME IS INCREASED LV Ptm required, to open A also decreased V, DEREASESD WORK OF PUMPING Tension generated in muscle fibre also decreased Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 42. LV PRESSURE VOLUME CURVE d-AVC 150 C-AVO LVESPVR b-MVC d a-MVO 50 Isovolemic contraction c isovolemic relaxation LV Pressure 100 a LVESDVR b LV volume 50 130 Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 43. CARDIAC MUSLCE LENGTH TENSION CURVE Isometric contraction Isometric relaxation Muscle tension End systolic length End diastolic length Muscle length Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 44. LV PRESSURE VOLUME CURVE LVESPVR 150 Afterload = 90 mm Hg SV = 80 ml Afterload = 70 mm Hg LV Pressure 100 SV = 105 ml 50 LVESDVR LV volume 25 50 130 Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 45. CARDIAC MUSLCE LENGTH TENSION CURVE Muscle tension Peak isometric tension Resting tension Muscle length Decreased muscle tension Decreased wall stress Decreased work Decreased oxygen requirement Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 46. Clinical implications This increase or decrease in afterload will have marked effect in LV dysfunction poor frank starling curve Marked variation in pleural pressure esp negative lung airway and parenchymal disease Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 47. RV afterload, Pulmonary circulation, LV preload & Lung volume Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 48. PVR lung volume and PVR (RV afterload) (bimodal relation) RV FRC Lung volume Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India TLC
- 49. West zones of pulmonary circulation Pa=Pulmonary arterial pressu PA=Alveolar pressure Pv=Pulmonary venous pressu PA >Pa >Pv Pa >PA >Pv Pa >Pv >PA Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 50. Ventricular Interdependence Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 51. pericardium RV LV Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 52. For heart Psur is pericardial pressure (Ppc) Ttm = Pim – Ppc Pericardium high extensibility at lowlevel of stress with an abrupt transition to relative inextensibility at higher stress therefore it exerts a restraining effect on volume of heart Physiologic role of normal pericardium Matthew W. Watkins, Martin M. LeWinter, annu. Rev. Med 993;44:171-180 Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 53. RV & LV mechanically coupled common septum & circumferential fibres expansion of both ventricles constrained by a common pericardium (pericardial constraint) Diastolic filling of one ventricle has to be at the cost of another diastolic filling of one ventricle will affect the geometry and stiffness of another PARELLEL INTERDEPENDENCE Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 54. Changes in RVEDV, changed LV diastolic compliance RV end diastolic volume 50 LV pressure (mmHg) 20 35 10 5 10 20 30 40 LV end diastolic volume (ml) Heart lung interactions. Pinsky MR, Textbook of Critical Care, 5th edition, Elsvier Saunders Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India 20 0
- 55. Output of RV is preload of LV SERIES INTERDEPENDENCE Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 56. Myocardial contractility is not significantly affected by ITP Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
- 57. So This was …… heart……. .lung……………… Is our interaction still preserved? Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India interaction
- 60. ……..Thank You