Dr.Hasanul Arifin SpAn. Departemen/SMF Anestesiologi dan Reanimasi FK-USU/RSUP.H. ADAM MALIK

Transkripsi

1 VENTILATION PERFUSION RELATION SHIPS Dr.Hasanul Arifin SpAn Departemen/SMF Anestesiologi dan Reanimasi FK-USU/RSUP.H. ADAM MALIK MEDAN 1

2 PROSES PERNAFASAN Gabungan mekanisme yang berperan dalam suplai oksigen keseluruh sel dan eliminasi karbon dioksida KOMPONEN YANG BERPERAN Ventilasi Difusi Perfusi 2

3 3 Processes: 1. Ventilation -movement of air in & out -- depends on system of open (clear) airways & movement of respiratory muscles, primarily the diaphragm which is innervated by the phrenic nerve. 2. Diffusion -exchange & transport gases (need perfusion/pulmonary circulation) 3. Perfusion HUBUNGAN VENTILASI/PERFUSI 1. Ventilasi : jumlah dari semua volume udara yang diekshalasi dalam 1 menit Minute Volume = VT X Frek. Nafas Ventilasi Alveolar = Frek. Nafas x (VT VD) DEAD SPACE Non Respirasi (Anatomik Dead Space) Non Perfusi (Alveolar Dead Space) Physiological Dead Space 3

4 VENTILASI Jumlah udara/gas yang mengadakan pertukaran dalam alveoli setiap menit Dipengaruhi oleh : Patensi jalan nafas Posisi tubuh Volume paru Dead space Shunting 4

5 Patensi Jalan Nafas : obstruksi Infeksi tumor Posisi Tubuh : tegak terlentang miring Volume Paru : otot pernafasan penyakit paru space occupying lesion tekanan intra abdominal nyeri, obat The effect of gravity on alveolar compliance in the upright position. 5

6 VENTILATION Proses transport gas antara alveolus dan atsmosfir Pertukaran gas ini akan berkurang pada ; obstructive restrictive combined ventilation disorders Contoh : Laparotomi abdomen atas COPD (Chronic Obstructive Pulmonary Disease) Status Asthmaticus CNS dan obat- obatan : sedation, intoxication Neuromuscular : myasthenia gravis, muscle relaxant PERFUSION Aliran darah paru yang bertanggung jawab membawa CO 2 ke alveoli dan sebaliknya membawa O 2 dari alveoli ke jantung Perfusion disorder : Pulmonary embolism Sumbatan pada mikrosirkulasi paru karena agregasi platelet dan granulosit : septicemia peritonitis acute pancreatitis Extra pulmonary : reduced CO pada gagal jantung, atau pada kondisi syok 6

7 Bronkiolus terminalis Bronkiolus respiratorius Alveoli Pori-pori Kohn 7

8 SIRKULASI PULMONER Sifat : Tekanan pembuluh darah rendah, MAP 8-15 mmhg Mudah mengembang (distensible) Resistensi rendah Dalam keadaan istirahat, perfusi pulmoner, sekitar = 70 ml x 80 x/mnt = 5,6 L/mnt Pintasan Fisiologis = jumlah darah yang melintas dari kanan ke kiri tanpa mendapat oksigenisasi dan dekarboksilasi paru (sekitar 5 % curah jantung) The three-zone model of the lung. A: Upright position. B: Supine position. 8

9 Diffusion Transport of gases between the alveoli and (pulmonary) capillaries and eventually from the capillaries to the tissues diffusion dependent on perfusion and the partial pressure (pp) exerted by each gas (each gas in a mixture of gases exerts a partial pressure, a property determined by the concentration of the gas) gases diffuse from area of conc. (pp) to conc. (pp) concentration pp of gas diffusion CO 2 more soluble more soluble than O 2, therefore it diffuses faster 9

10 MEMBRAN ALVEOLO-KAPILER: -adalah permukaan antar alveolidan endotel kapiler -Tempat O 2 berdifusi dari alveolike kapiler darah /CO 2 berdifusi dari kapiler ke alveol 10

11 The pulmonary interstitial space, with a capillary passing between the two alveoli. The capillary is incorporated into the thin (gas-exchanging) side of the alveolus on the right. The interstitial space is incorporated into the thick side of the alveolus on the left. (Redrawn and reproduced, with permission, from Nunn JF: Applied Physiology, 4th ed. Butterworth, 1993.) Factors Affecting Diffusion surface area in the lung (e.g., lobectomy, atelectasis, emphysema) thickness of alveolar-capillary membrane (e.g., edema, pneumonia) differences in partial pressure of gases on either side Characteristics of the gas (CO 2 diffuses faster) 11

12 PERTUKARAN GAS Oxygenation UDARA BEBAS: PiO 2 : 21% x 760 = 160 mmhg PiCO 2 : 0.04 % x 760 = 0.3 mmhg PiN 2 : 78.6 % x 760 = 597mmHg PiH 2 O : 0.46 % x 760 = 3.5 mmhg PROSES DIFUSI N 2 PAN 2 : 573 mmhg H 2 O PAH 2 O: 47 mmhg ALVEOLUS KAPILER PARU Pulmonary Artery O 2 PvO 2 : 40 mmhg PAO 2 : 104 mmhg O 2 PACO 2 : 40 mmhg CO 2 CO 2 CO 2 PcCO 2 : 45 PcCO 2 : 40 mmhg PcO2: 100 mmhg mmhg Pulmonary Vein PaO 2 O 2 PAO 2 PcO 2 12

13 SHUNT DAN DEAD SPACE Airway VENTILASI Alveoli DIFUSI PERFUSI Kapiler darah 13

14 Airway Sumbatan No VENTILASI Alveoli PERFUSI Blood flow Kapiler darah SHUNT UNIT (PERFUSION WITHOUT VENTILATION) SHUNT UNIT 14

15 The distribution of / ratios for the whole lung (A) and according to height (B) in the upright position. Note that blood flow increases more rapidly than ventilation in dependent areas. (Reproduced, with permission, from West JB: Ventilation/Blood Flow and Gas Exchange, 3rd ed. Blackwell, 1977.) A three-compartment model of gas exchange in the lungs, showing dead space ventilation, normal alveolar capillary exchange, and shunting (venous admixture).(modified and reproduced, with permission, from Nunn JF: Applied Respiratory Physiology, 5th ed. Lumb A [editor]. Butterworth-Heinemann, 2000.) 15

16 SHUNTING (Intrapulmonary Right-to-Left Shunt) ANATOMICAL Bronchial Pleural Thabesian CHD (Congenital Heart Disease) Tumor Paru Arteriovenous Anastomosis FUNCTIONAL Atelectasis Pneumothorax Hematothorax Pleural effusion Pulmonary edema Pneumonia Acute Respiratory Failure (ARDS) SHUNT % % 10% PaO % 30% FiO 2 50%

17 DEAD SPACE Volume udara yang di hirup dalam satu kali bernafas yang tidak turut berdifusi dalam alveolus FUNCTIONAL DEAD SPACE ANATOMICAL ALVEOLAR Airway VENTILASI Alveoli NO PERFUSI Kapiler darah No Blood flow DEAD SPACE UNIT (VENTILATION WITHOUT PERFUSION) 17

18 DEAD SPACE UNIT Hubungan Ventilasi (V) dan Perfusi (Q) TRAKEA ANATOMICAL DEAD SPACE KAPILER PARU V/Q = V/Q > 1 V/Q = 1 V/Q < 1 V/Q = 0 ALVEOLAR DEAD SPACE NORMAL VENOUS ADMIXTURE (SHUNT) PHYSIOLOGICAL DEAD SPACE MECHANICAL DEAD SPACE: TUBE CONNECTOR ET CO2 BREATHING CIRCUIT 18

19 19

20 20

21 ~0.8 21

22 Components of the normal venous admixture.(reproduced, with permission, from Nunn JF: Applied Respiratory Physiology, 5th ed. Lumb A [editor]. Butterworth-Heinemann, 2000.) 22

23 Optimum gas exchange requires: Ventilation/perfusion match (high V/Q ratio) In healthy lungs this ratio is close to 1:1 Perfusion greater in dependent areas of the lung Ventilation also greater in dependent areas of the lung Measure adequacy of V/Q match through ABGs V/Q mismatches In areas where perfusion > ventilation, a shuntexists. Blood bypasses the alveoli without gas exchange occurring (e.g., pneumonia, atelectasis, tumor, mucus plug) All cause obstruction in the distal airways, decreasing ventilation 23

24 In areas where ventilation > perfusion, dead space results. The alveoli do not have an adequate blood supply for gas exchange to occur (e.g., pulmonary emboli, pulmonary infarct, cardiogenic shock). In areas where both perfusion and ventilation are limited or absent, a silent unit exists (e.g., pneumothorax, severe ARDS). 24

25 MEASURED PARAMETERS CALCULATED PARAMETERS Arterial Oxygen Tension (PaO 2 ) Arterial Carbon Dioxide Tension (PaCO 2 ) Arterial Oxygen Saturation (SaO 2 or SpO 2 ) Mixed Venous Oxygen Saturation (SvO 2 ) Venous Oxygen Tension (PvO 2 ) Hemoglobin (Hgb) Cardiac Output (CO) Pulmonary Capillary Oxygen Content (CcO 2 ) Arterial Oxygen Content (CaO 2 ) Venous Oxygen Content (CvO 2 ) Arterial-Venous Oxygen Content Difference (Ca-vO 2 ) Oxygen Utilization Coefficient (OUC) Oxygen Delivery Index (DO 2 I) Oxygen Consumption Index (VO 2 I) Intrapulmonary Shunt (Qs/Qt) Cardiac Index (CI) 6 Key steps in oxygen cascade O 2 Uptake in the Lung Haemoglobin Oxygenation Carrying capacity PaO 2 SaO 2 - Ht CaO 2 DO 2 Delivery Cardiac Output Flow rate - ø Organ distribution Autoregulation Nervous Syst Humoral Local Control Diffusion TISSUE OXYGENATION Distance TISSUE OXYGENATION Cellular use Mitochondria VO 2 Contraction 25

26 Oksigen ditranspor ke jaringan dalam 2 bentuk Terlarut dalam plasma Berikatan dengan hemoglobin OXYGEN DELIVERY DO2 = CO X CaO2 (ml/ menit) (ml O2 / 100 ml Blood) = 1000 ml O2 / menit CaO2 = (SaO2 x Hb x 1,341) + (PaO2 x 0,0003) = 20 ml O2 / 100 ml Blood DO 2 = oxygen delivery VO 2 = oxygen consumption SaO 2 = arterial oxygen saturation SvO 2 = mixed venous oxygen saturation Q = cardiac output Hb = hemoglobin concentration PaO 2 = arterial oxygen tension PvO 2 = mixed venous oxygen tension 26

27 Oxygen Content dalam darah = Hb bound plus dissolved CaO 2 = [Hb] x 1.34 x % saturation + PO 2 x ml O 2 / dl / mm Hg Kurva Disosiasi Hemoglobin 27

28 Oxygen Dissociation Curve Karena pengikatan oksigen jarang menimbulkan masalah, maka perhatian khusus diarahkan terhadap pelepasan oksigen oleh Hb dijaringan. Acidemia, hiperkarbia, dandemam akan menggeser kurva disosiasi ke kanan sehingga akan memperbaiki/mempermudah pelepasan oksigen di jaringan Oxygen Dissociation Curve O 2 Sat (%) , 50% 40, 75% 60, 90% 100, 97% PO 2 (mm Hg) 28

29 O 2 Sat (%) flat portion of curve: large changes of PO 2 result in very small changes in oxygen saturation or content PO 2 (mm Hg) 100 O2 Sat (%) steep portion of curve: small changes of PO 2 result in large changes in oxygen saturation or content. Results in enhanced oxygen release PO2 (mm Hg) 29

30 Four Things Change Oxyhemoglobin Affinity Hydrogen Ion Concentration, [H + ] Carbon Dioxide Partial Pressure, PCO 2 Temperature [2,3-DPG] Hydrogen Ion Inhibited Unloading Better Unloading 30

31 Carbon Dioxide Temperature 31

32 Acute DO 2 Anemia Hypoxemia HR CO If failed O 2 ER = 25% 50% VO 2 SvO 2 50% O 2 return 500 GANGGUAN SISTEM PERNAFASAN & PENYEBAB OTAK SYARAF TRAUMA NARKOTIKA DEPRESSANT / ANESTHETIC INFEKSI, PERDARAHAN GUILLAIN BARRE POLIOMYELITIS, POLINEUROSIS MYASTHENIA GRAVIS OTOT TETANUS RELAXANT / CURARE JALAN NAFAS ALVEOLI RONGGA THORAX ASTHMABRONCHIALE EDEMA PARU ATELEKTASIS FRACTURE COSTAE PNEUMOTHORAX HEMATOTHORAX 32

33 Thank you for listening 33