VENTILATION PERFUSION RELATION SHIPS
Dr.Hasanul Arifin SpAn Departemen/SMF Anestesiologi dan Reanimasi FK-USU/RSUP.H. ADAM MALIK MEDAN
PROSES PERNAFASAN Gabungan mekanisme yang berperan dalam suplai oksigen keseluruh sel dan eliminasi karbon dioksida KOMPONEN YANG BERPERAN Ventilasi Difusi Perfusi
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)
Non Respirasi (Anatomik Dead Space)
DEAD SPACE Non Perfusi (Alveolar Dead Space)
Physiological Dead Space
VENTILASI Jumlah udara / gas yang mengadakan pertukaran dalam alveoli setiap menit
Dipengaruhi oleh : Patensi jalan nafas Posisi tubuh Volume paru “Dead space” “Shunting”
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.
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 CO2 ke alveoli dan sebaliknya membawa O2 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
Bronkiolus terminalis
Bronkiolus respiratorius
Alveoli Pori-pori Kohn
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.
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 CO2 more soluble than O2, therefore it diffuses faster
MEMBRAN ALVEOLO-KAPILER: - adalah permukaan antar alveoli dan endotel kapiler
- Tempat O2 berdifusi dari alveoli ke kapiler darah /CO2 berdifusi dari kapiler ke alveol
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 (CO2 diffuses faster)
PERTUKARAN GAS
Oxygenation UDARA BEBAS: PiO2
:
21% x 760 = 160 mmHg
PiCO2 : 0.04 % x 760 = 0.3 mmHg PiN2
ALVEOLUS
: 78.6 % x 760 = 597mmHg
PiH2O : 0.46 % x 760 = 3.5 mmHg
N2
PAN2: 573 mmHg
PROSES DIFUSI
H2O
PAO2: 104 mmHg
Pulmonary Artery O2 PvO2: 40 mmHg
O2 CO2
PAH2O: 47 mmHg PACO2: 40 mmHg
CO2
KAPILER PARU
Pulmonary Vein PaO2 O2
CO2
PcCO2: 45 PcCO2: 40 PcO2: 100 mmHg mmHg mmHg
∴ PAO2 ≈ PcO2
SHUNT DAN DEAD SPACE
Airway
VENTILASI
Alveoli
PERFUSI DIFUSI
Kapiler darah
Airway
Sumbatan
Alveoli
No VENTILASI
PERFUSI
Blood flow
Kapiler darah SHUNT UNIT
(PERFUSION WITHOUT VENTILATION)
SHUNT UNIT
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.)
SHUNTING (Intrapulmonary Right-to-Left Shunt) ANATOMICAL
FUNCTIONAL
Bronchial
Atelectasis
Pleural
Pneumothorax
Thabesian
Hematothorax
CHD (Congenital Heart Disease)
Pleural effusion
Tumor Paru
Pulmonary edema
Arteriovenous Anastomosis
Pneumonia Acute Respiratory Failure (ARDS)
SHUNT % 2-3% 10%
500 400 PaO2 300
20%
200 30%
100 0
21
40 60 FiO2
80
50% 100
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 No Blood flow
Kapiler darah DEAD SPACE UNIT (VENTILATION WITHOUT PERFUSION)
DEAD SPACE UNIT
Hubungan Ventilasi (V) dan Perfusi (Q) ANATOMICAL DEAD SPACE
TRAKEA
PHYSIOLOGICAL DEAD SPACE
V/Q = ∝
KAPILER PARU
ALVEOLAR DEAD SPACE V/Q > 1
MECHANICAL DEAD SPACE: TUBE
V/Q = 1
NORMAL
CONNECTOR ET CO2 BREATHING CIRCUIT
V/Q < 1
VENOUS ADMIXTURE (SHUNT) V/Q = 0
~0.8
Components of the normal venous admixture.(Reproduced, with permission, from Nunn JF: Applied Respiratory Physiology, 5th ed. Lumb A [editor]. Butterworth-Heinemann, 2000.)
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 shunt exists. Blood bypasses the alveoli without gas exchange occurring (e.g., pneumonia, atelectasis, tumor, mucus plug) All cause obstruction in the distal airways, decreasing ventilation
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).
MEASURED PARAMETERS
CALCULATED PARAMETERS
Pulmonary Capillary Oxygen Arterial Oxygen Tension (PaO2) Content (CcO2) Arterial Carbon Dioxide Tension Arterial Oxygen Content (CaO2) (PaCO2) Venous Oxygen Content (CvO2) Arterial Oxygen Saturation Arterial-Venous Oxygen Content (SaO2 or SpO2) Mixed Venous Oxygen Saturation Difference (Ca-vO2) Oxygen Utilization Coefficient (OUC) (SvO2) Oxygen Delivery Index (DO2I) Venous Oxygen Tension (PvO2) Oxygen Consumption Index (VO2I) Hemoglobin (Hgb) Intrapulmonary Shunt (Qs/Qt) Cardiac Output (CO) Cardiac Index (CI)
6 Key steps in oxygen cascade O2 Uptake in the Lung
Oxygenation
PaO2
CaO2 Haemoglobin Delivery Organ distribution
DO2
Carrying capacity SaO2 - Ht Cardiac Output
Flow rate - ø Nervous Syst Humoral Local Control
Autoregulation
Distance TISSUE OXYGENATION
Diffusion
Cellular use
Mitochondria
VO2
Contraction
Oksigen ditranspor ke jaringan dalam 2 bentuk Terlarut dalam plasma Berikatan dengan hemoglobin
OXYGEN DELIVERY DO2 = =
CO X (ml / menit)
CaO2 (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 DO2 = oxygen delivery VO2 = oxygen consumption SaO2 = arterial oxygen saturation SvO2 = mixed venous oxygen saturation
Q = cardiac output Hb = hemoglobin concentration PaO2 = arterial oxygen tension PvO2 = mixed venous oxygen tension
Oxygen Content dalam darah = Hb bound plus dissolved
CaO2 = [Hb] x 1.34 x % saturation
+ PO2 x 0.003 ml O2/ dl / mm Hg
Kurva Disosiasi Hemoglobin
Oxygen Dissociation Curve Karena pengikatan oksigen jarang menimbulkan masalah, maka perhatian khusus diarahkan terhadap pelepasan oksigen oleh Hb di jaringan.
Acidemia, hiperkarbia, dan demam akan menggeser kurva disosiasi ke kanan sehingga akan memperbaiki / mempermudah pelepasan oksigen di jaringan
Oxygen Dissociation Curve 100 60, 90% 75 O2 Sat (%)
100, 97%
40, 75%
50
27, 50%
25
10 20
30 40
50 60
70 80
PO2 (mm Hg)
90 100
100 80
O2 Sat (%)
flat portion of curve: large changes of PO2 result in very small changes in oxygen saturation or content.
60 40 20
10
20
30
40
50
60
70
80
PO2 (mm Hg)
90
100
100 80
steep portion of curve: small changes of PO2 result in large changes in oxygen saturation or content. Results in enhanced oxygen release.
O2 Sat 60 (%) 40 20
10
20
30
40
50
60
70
PO2 (mm Hg)
80
90
100
Four Things Change Oxyhemoglobin Affinity Hydrogen Ion Concentration, [H+] Carbon Dioxide Partial Pressure, PCO2 Temperature [2,3-DPG]
Hydrogen Ion
Inhibited Unloading
Better Unloading
Carbon Dioxide
Temperature
Acute ↓ DO2 •Anemia •Hypoxemia •CO↓
HR If failed
O2ER = 50% 25%
SvO2 ↓ 50%
VO2
O2 return ↓ 500
GANGGUAN SISTEM PERNAFASAN & PENYEBAB OTAK
SYARAF
OTOT
TRAUMA NARKOTIKA DEPRESSANT / ANESTHETIC INFEKSI , PERDARAHAN
GUILLAIN BARRE POLIOMYELITIS , POLINEUROSIS MYASTHENIA GRAVIS
TETANUS RELAXANT / CURARE
JALAN NAFAS
ALVEOLI
• ASTHMABRONCHIALE
EDEMA PARU ATELEKTASIS
RONGGA THORAX FRACTURE COSTAE PNEUMOTHORAX HEMATOTHORAX
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