4 - Cardio-Pulmonary System

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Cardio-Pulmonary System James H. Philip, M.E.(E.), M.D. Anesthesiologist and Director of Technology Assessment Brigham and Women's Hospital Medical Liaison, Department of Biomedical Engineering Partners HealthCare System Associate Professor of Anaesthesia Harvard Medical School I have a financial interest in Gas Man ® and Med Man Simulations, Inc. I have performed research on some of the drugs or devices described © , James H Philip, all rights reserved.

Objectives - Cardio-pulmonary System Why we need it What it is What it does How it does it How we measure it now How we will measure it

Why Oxygen is inhaled by the lungs Oxygen (and sugar) are transported to tissues, cells, and then mitochondria Mitochondria O CHO -> H 2 O + 2CO 2 + Energy Carbon dioxide is transported from mitochondria, cells, tissues to lungs Carbon dioxide is exhaled by the lungs

Cardio-Pulmonary system Lungs Tissues

Why did I lump systems? Cardiac Vascular Pulmonary Three systems Combine to allow life All are necessary Monitoring often involves them all

What it is (Cardio-Pulmonary system) Heart is a pump Lungs bring oxygen from air into blood Circulation transports: lungs tissues Oxygen to tissues Carbon dioxide from tissues Lungs bring carbon dioxide from blood into air

Heart, opened for clarity

Heart, schematized for more clarity

Heart Chambers RA RV LA LV

Heart Chambers RA RV LA LV Right Atrium Left Atrium Left Ventricle Right Ventricle

Venous return from tissues RA RV LA LV

SVC Superior Vena Cava RA RV LA LV IVC Inferior Vena Cava

RA -> RV RA RV LA LV

PA Pulmonary artery RA RV LA LV

Lungs RA RV LA LV

Heart, opened for clarity

RA RV

Heart, opened for clarity RA RV Tricusped Valve

Heart, opened for clarity RA RV Tricusped Valve Pulmonic Valve

Heart, opened for clarity

LA LV

Heart, opened for clarity LA LV Mitral valve (2 cusps)

Heart, opened for clarity LV Aorta

Heart, opened for clarity LV Aorta Aortic valve

Lungs

Trachea

Lungs Trachea Mainstem bronchi

Lungs Trachea Mainstem bronchi R L

Lungs Trachea Mainstem bronchi R L Smaller Bronchi Bronchioles Alveoli

Alveolus

Pulomnary artery blood Pulmonary vein blood

Alveolus Pulomnary artery blood Pulmonary vein blood High CO 2 Low O 2

Alveolus Pulomnary artery blood Pulmonary vein blood High CO 2 Low O 2 loses CO 2 gains O 2

Alveolus Pulomnary artery blood Pulmonary vein blood High CO 2 Low O 2 Low CO 2 High O 2

Alveolus Oxygen diffuses into blood

Alveolus Carbon dioxide diffuses out of blood

Nomenclature Mostly jargon Not done to intentionally convuse But usually does so, anyway Start with COCardiac Output

Cardiac Output How much blood the heart pumps in one minute must equal blood which returned from tissues Paradox Return or Pumping capability can limit! Useful physiologic variable Ocasionally doesn’t give the whole answer

Abbreviations BSABody Surface Area IndexParameter / BSA CICardiac Index (= CO / BSA) COCardiac Output MAPMean Arterial Pressure MPAPMean Pulmonary Artery Pressure PCWPPulmonary Capillary Wedge Pressure LVEDPLeft Ventricular End-Diastolic Pressure LAPLeft Atrial Pressure PVRPulmonary Vascular Resistance RAPRight Atrial Pressure R/L VSWIRight / Left Ventricular Stroke Work Index R/L CWRight / Left Cardiac Work SVStroke Volume SVIStroke Volume Index (=SV/BSA) SVRSystemic Vascular Resistance

Filling Pressures

Pulmonary Vessels LA LV Lungs PA PC Pulmonary Capillaries

Pulmonary Artery Pressure PAP LA

Pulmonary Capillary Wedge Pressure PCWP

Pulmonary Capillary Wedge Pressure PCWP ≈ PA diastolic pressure

Schematic View

Central Circulation LA LVAo PVPA RA RV SVC IVC PC

Right Ventricle LA LVAo PVPA RA RV SVC IVC PC RVEDP = Right Ventricular End-Diastolic Pressure

Right Ventricle LA LVAo PVPA RA RV SVC IVC PC RVEDP = Right Ventricular End-Diastolic Pressure = Pressure in RV before it contracts = Starting pressure = pre-lad

Right Atrium LA LVAo PVPA RA RV SVC IVC PC RAP = RVEDP

Right Atrium LA LVAo PVPA RA RV SVC IVC PC RAP = RVEDP End of diastole, the A-V valves are open Pressures are equal =

Right Atrium LA LVAo PVPA RA RV SVC IVC PC CVP = RAP Central Venous Pressure = Right Atrial Pressure

CVP = RAP = RH Filling Pressure LA LVAo PVPA RA RV SVC IVC PC CVP = RAP Central Venous Pressure = Right Atrial Pressure = Right Heart Filling Pressure

R Heart Filling Pressure is Easy to measure LA LVAo PVPA RA RV SVC IVC PC CVP = RAP Central Venous Pressure = Right Atrial Pressure = Right Heart Filling Pressure

R Heart Filling Pressure is Easy to measure LA LVAo PVPA RA RV SVC IVC PC CVP = RAP Central Venous Pressure = Right Atrial Pressure = Right Heart Filling Pressure Neck vein (internal jugular IJ)

L Heart Filling Pressure LA LVAo PVPA RA RV SVC IVC PC Neck vein (internal jugular IJ) Can’t get there from here

L Heart Filling Pressure LA LVAo PVPA RA RV SVC IVC PC Neck vein (internal jugular IJ) Can’t get there from anywhere

L Heart Filling Pressure LA LVAo PA RA RV SVC IVC PC Neck vein (internal jugular IJ) PV Wedge a balloon in the a capillary

L Heart Filling Pressure LA LVAo PA RA RV SVC IVC PC Neck vein (internal jugular IJ) PV Wedge a balloon in the a capillary Produce Pulmonary Capillary Wedge Pressure PCWP

L Heart Filling Pressure LA LVAo PA RA RV SVC IVC PC Neck vein (internal jugular IJ) PV Wedge a balloon in the a capillary Produce Pulmonary Capillary Wedge Pressure PCWP = LAP

PCWP = L Heart Filling Pressure LA LVAo PA RA RV SVC IVC PC Neck vein (internal jugular IJ) PV Wedge a balloon in the a capillary Produce Pulmonary Capillary Wedge Pressure PCWP = LAP

By-the-stroke analysis Cardiac Output = (Heart Rate) x (Stroke Volume) CO = HR x SV Units: Cardiac Output = [strokes/min] x [mL / stroke] = mL / min CO = HR x SV —> SV = CO / HR Example CO = 5 L / min = 5,000 mL / min; HR = 50 / min SV = [ 5,000 mL / min ] / [ 50 / min ] = 100 mL

Cardiac Work Stroke Work = (Pressure rise) x (Stroke Volume) Stroke Work = ∆ P x ∆ V ∆ P = pressure after chamber - pressure before chamber LV: MAP - LVEDP = MAP - PCWP

Some Cardiovascular Parameters Cardiac Output = (Heart Rate) x (Stroke Volume) Units: Cardiac Output = strokes/min x mL / stroke = mL / min = flow rate Left Ventricular Stroke Work = LVSW = SV (MAP - PCWP) Left Ventricular Stroke Work IndexLVSWI = SV (MAP-PCWP)/BSA Right Ventricular Stroke Work IndexRVSWI = SV (MPAP-RAP)/BSA Left Cardiac WorkLCW = CO MAP / BSA Right Cardiac WorkRCW = CO MPAP / BSA

Pressure - Flow relationship V (voltage) = I (current) x R (resistance) P (pressure) = F (flow or CO) x R (resistance) P = F x R; R = P / F = ∆ P / F Pulmonary Vascular Resistance PVR = (MPAP-PAWP) / CO Systemic Vascular Resistance SVR = (MAP-RAP) / CO

Pressure - Flow relationship V (voltage) = I (current) x R (resistance) P (pressure) = F (flow or CO) x R (resistance) P = F x R; R = P / F = ∆ P / F Pulmonary Vascular Resistance PVR = (MPAP-PAWP) / CO Systemic Vascular Resistance SVR = (MAP-RAP) / CO

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