Download presentation
Presentation is loading. Please wait.
1
Applied physiology – II: Respiration, oxygen therapy Molnár Zsolt AITI
2
Anatomy, physiology - the missing link…
3
Upper airway The nose: Clears Heats (32-36) humidifies (90%)
4
The larynx Which is the narrowest part?
5
The larynx Which is the narrowest part? Cricoid and acute surgery
6
The larynx Which is the narrowest part? Cricoid and acute surgery
Epiglottis Tracheostomy
7
Anatomy - thorax Breathing Intrapleural pressure:
Inspiration: active Expiration: passive End expiratory pause Intrapleural pressure: Normal value: ±2-3 cmH2O Coughing, sneezing: > 60 cmH2O Peak inspiratory flow (PIF) PIF at rest ~ l/min
8
Gas exchange Function of breathing Acute respiratory failure
Oxigenation CO2-elimination Acute respiratory failure Type I: hypoxic Type II: hypercapnic Mixed or global
9
Alveolar oxygenation Molnár ‘99 PAO2=FiO2 x [(PB-PH2O) – PaCO2/R]
PiO2~ 150 mmHg PvO2=40 mmHg PAO2=FiO2 x [(PB-PH2O) – PaCO2/R] PAO2 120 mmHg PaO2~100 mmHg PA-aO2 20 mmHg Molnár ‘99
![Alveolar oxygenation Molnár ‘99 PAO2=FiO2 x [(PB-PH2O) – PaCO2/R]](http://slideplayer.com/slide/8773126/26/images/9/Alveolar+oxygenation+Moln%C3%A1r+%E2%80%9899+PAO2%3DFiO2+x+%5B%28PB-PH2O%29+%E2%80%93+PaCO2%2FR%5D.jpg "PiO2~ 150 mmHg. PvO2=40 mmHg. PAO2=FiO2 x [(PB-PH2O) – PaCO2/R] PAO mmHg. PaO2~100 mmHg. PA-aO2 20 mmHg. Molnár ‘99.")
10
Venous admixture Molnár ‘99 PvO2=40 mmHg 120
PaO2 = (120+40)/2 = 80 mmHg PA-aO2 = 40 mmHg Molnár ‘99
11
Closing capacity (CC) Normal lungs: ALI/ARDS: CC in ERV FRC>CC
CC in VT FRC<CC VT ERV FRC CC CC RV
12
Atelectasis and venous admixture
PvO2=40 mmHg 120 mmHg PaO2 = (120+40)/2 = 80 mmHg Molnár ‘99
13
Atelectasis and venous admixture
PvO2=40 mmHg 180 Hgmm PaO2 = (120+40)/2 = 80 mmHg instead PaO2 = (180+40)/2 = 120 mmHg Molnár ‘99
14
Degree of venous admixture
5% 10% 400 15% 20% „Iso-shunt” diagram Nunn JF. Appl. Resp Physiol., 1993 300 PaO2 Hgmm 25% 200 30% 100 50% 0,2 0,6 1,0 FiO2 Molnár ‘99
15
Oxygen therapy
16
O2 therapy - indications
Respiratory distress (resp. rate>24/min or laboured breathing) Asthmatic attack Hypotension (RRsyst < 100 mmHg) Signs of abnormal heart function Metabolikc acidosis (act HCO3 < 18 mmol/l) Suspected AMI Severe trauma and/or severe blood loss Sepsis Altered level of consciousness Drug overdose with confusion Smoke, CO, toxic gas inhalation Complications during labour Transport of the critically ill Every postoperative condition A hipovolémia során a keringő vérmennyiség csökkenése a … Molnár ‘99
17
Variable performance devices
10 10
18
Features Breathing cycle Peak inspiratory flow (PIF):
Inspiration – expiration – end expiratory pause Peak inspiratory flow (PIF): At rest ~ l/min Forced inspiration >60 l/min Variable performance devices Fresh gas flow < PIF Performance depends on patient’s breathing pattern Types Nasal specs - Face mask – Mask with reservoire balloon Molnár ‘99
19
O2-rotameter 3 O2 ports/bed Flow:0-16 L/min Molnár ‘99
A hipovolémia során a keringő vérmennyiség csökkenése a … Molnár ‘99
20
Nasal specs FiO2 ~ 30% Flow: 2-6 L/min Comfortable, cheap
Dries nasal mucous tissues Molnár ‘99
21
Face mask Increases dead space Flow: 5-10 L/min FiO2 ~ 50%
Humidification unsolved Molnár ‘99
22
Mask with a reservoire Flow: 5-15 L/min Balloon FiO2 ~ 80%
Humidification unsolved Molnár ‘99
23
Oxygen therapy Fix performance devices 10 10
24
Features Independent from patient’s breathing pattern Reason: Types
High fresh gas flow > PIF Types Venturi-masks Anaesthetic breathing curcuits: Mapleson-systems Respirators Molnár ‘99
25
Daniel Bernoulli Bernoulli’s principle
„…increase in the speed of the fluid occurs simultaneously with a decrease in pressure or a decrease in the fluid's potential energy” Molnár ‘99 1738
26
Giovanni Battista Venturi
Venturi’s principle and injector „…fluid velocity must increase through the constriction to satisfy the equation of continuity, the gain in kinetic energy is balanced by a drop in pressure or a pressure gradient force” Molnár ‘99
27
Giovanni Battista Venturi
Venturi’s principle and injector „…fluid velocity must increase through the constriction to satisfy the equation of continuity, the gain in kinetic energy is balanced by a drop in pressure or a pressure gradient force” 8 LPM 50% O2 100* X*21 = (8+X)*50 4 = 0.3X 13 = X Fresh gas flow = = 21 LPM Molnár ‘99
28
From Venturi to Vinturi
21st century: Molnár ‘99
29
Venturi’s injector + humidification
Air 20-50% FiO2 60-30 L/min Bernoulli effect Humidification Warm water container Heating wire A hipovolémia során a keringő vérmennyiség csökkenése a … Molnár ‘99
30
Side effects of oxygen therapy
Insignificant comparing to the benefits Claustrophoby Dry mucous membranes Respiratory depression (COPD) Hyperoxia A hipovolémia során a keringő vérmennyiség csökkenése a … Molnár ‘99
31
Monitoring 10 10
32
Pulsoximetry Pletismograph and Oximeter Molnár ‘99
A hipovolémia során a keringő vérmennyiség csökkenése a … Molnár ‘99
33
The pulsoximeter Continuous Doesn’t replace blood gas tests Molnár ‘99
A hipovolémia során a keringő vérmennyiség csökkenése a … Molnár ‘99
34
The pulsoximeter Reliability Reaction time
SaO2 ~ % (inaccuracy < 5%) SpO2 > 94% ~ SaO2>90% Van de Louw A et al. Intensive Care Med 2001; 27: 1606 Reaction time 5-8s Desaturation reaction time: Ear probes: Finger probes: On toes: Bishop ML. Anesthessiol Review 1994; 256: 1017 Molnár ‘99
35
First move in the care of a critically ill: Give oxygen!
Motto First move in the care of a critically ill: Give oxygen! 10 10
Similar presentations
