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1
OXYGEN THERAPY
& ARTIFICIAL
VENTILATION
Department of
Anaesthesiology & Intensive Medicine
Šafárik University Faculty of Medicine, Košice
MUDr. Jozef Firment, PhD.
2
REASONS OF HYPOXEMIA
IN POSTOPERATIVE PERIOD
• FiO2 decrease?
• V/Q disturbances – the most frequent
• Lung shunts – secretions, atelectases
• Hypoventilation – anesthesia efects
• Difussion disturbances – interstitial lung
oedema
• Hypoxia from difusion N2O 40 x > N2
3
PREDISPOSITION FACTORS
FOR RETENTION OF SECRETIONS
• Surgery site (thoracic, epigastrium >
hypogastrium)
• Preexist respiratory disease (infection,
hypersecretion)
• Smoking
• Obesity (FRC, WOB)
4
BRONCHIAL SECRETIONS
RETENTION IN POSTOPERATIVE
PERIOD
• Expectoration insufficiency (painful wound,
sedation, muscle weakness K+, P)
• bronchial ciliary activity (dry inspir. gases,
anesthetics)
• Antisialogic medicaments (premedication)
• Infection (washing mechanisms failure)
= atelectases, WOB, hypoxemia,
global respir. insuficiency
5
CONSEQUENCES OF
SECRETION RETENTION • Atelectasis:
during 24 h post surgery, fever 38-39oC,
tachycardia, tachypnoe, cough, cyanosis?, x-
ray - spot obscuration
• Bronchopneumonia:
Unusual lobar, elder pats., slower onset than
in atelectatic cause, fever, tachypnoe, x-ray –
more dense obscuration, especially basally
6 Duggan M., Kavanagh BP: Pulmonary Atelectasis. A Pathogenic Perioperative Entity.
Anesthesiology 2005; 102:838–54
7
Duggan M., Kavanagh BP: Pulmonary Atelectasis. A Pathogenic Perioperative Entity. Anesthesiology 2005; 102:838–54
8
LABORATORY
INVESTIGATIONS
• paO2, pcO2, pvO2 (ABR + pO2)
• possible mistakes and artefacts
steady state, taking of blood samples,
storage, laboratory
9
CHANGES OF FRC AND PaO2
IN POSTOPERATIVE TIME
10
POOSTOPERATIVE
PNEUMONIA TREATMENT
• ATB according to sputum cultivation
• Oxygen FiO2 0,3-0,4 according to ABB
• Artif. ventilat., non-responders to O2 and
activation of auxiliary respiratory
muscles, paO2, paCO2
11
GAS
EXCHANGE
DURING HYPO-
VENTILATION
Aitkenhead
12
WE
ST‘S
LU
NG
ZO
NE
S
Soni-O
HM
ED
A F
irm
ent
13
VENTILATORY MECHANICS
Evita 2 dura Dräger 1999
ARTIFICIAL BREATHING ATELECTASES
zone > ventilation
zone > perfusion
SPONTANEOUS BREATHING
14
SITUATIONS FOR LONGER OXYGEN
THERAPY DURING
POSTOPERATIVE PERIOD
• Hypotension
• IHD
• C.O.
• Anaemia
• Obesity
• Shivering
• Hypothermia
• Hyperthermia
• Lung oedema
• Airway
obstruction
• After large
procedures
15
OXYGEN CASCADE
16
OXYGEN THERAPY
• Every pt. 10 min after general
anaesthesia should obtain 100% oxygen
• Cave:
Recovery room
Postoperative dpt., ICU...
17
HYPERBAROXIA
http://www.hyperbarickecentrum.sk/podstata.html
18
HYPERBAROXIA
1. Air or Gas Embolism
2. Carbon Monoxide Poisoning
3. Clostridal Myositis and Myonecrosis (Gas Gangrene)
4. Crush Injury, Compartment Sy, & Acute Traumatic Ischemias
5. Decompression Sickness
6. Enhancement of Healing in Selected Problem Wounds
7. Exceptional Blood Loss (Anemia)
8. Intracranial Abscess
9. Necrotizing Soft Tissue Infections
10. Osteomyelitis (Refractory)
11. Delayed Radiation Injury (Soft Tissue and Bony Necrosis)
12. Skin Grafts & Flaps (Compromised)
13. Thermal Burns
http://www.uhms.org/Indications/indications.htm, http://www.oxynet.org/
19
EQUIPMENT FOR OXYGEN
THERAPY
Spont inspiration - Peak Inspiratory Flow = 20 - 30 l/min
• Nasal sonds
• Oxygen „eye-glasses“
• Face mask
• Venturi mask 4l 28%, 8l 40%, 15l 60%)
• CPAP 10 cmH20
• Artifitial ventilation
20
VENTI MASK
Cam
pbell
21
Campbell O2 FiO2 VT x f
l/min %
adult: 13 85-100 1000 x 15
- “ - 4 >40 dtto
child 5 85-100 300 x 20
- “ - 2 >40 dtto
Inflow O2 10 - 13 l/min
SELF-EXPANDING BAG
WITH O2
22
NECESSITY OF FiO2 CONTROL
• Normaly inspiratory force is regulated
by PaCO2 level (5,3 kPa)
• Patients regulated insiratory force by
paO2 (chronic bronchitis), 1-2 l/min O2,, 28% O2
• ARDS: paO2/FiO2 = shunt amount
23
RE
SP
ON
SE
Pa
O2
TO
OX
YG
EN
AD
MIN
IST
RA
TIO
N norma = 3 - 8%
13,3
24
PO
SIT
ION
OF
A. &
V.
PO
INT
S IN
VA
RIO
US
pH
A
itkenhead
25
Regulation of inspiratory
force by PaO2 decrease
In higher FiO2 threat
respiratory depresion
POSITION OF A. & V. POINTS
(PAT’S WITH CHRON. RESPIR. DISEASE)
26
BYPASS OF NASAL CAVITY Water vapour content r.h. 100% in 37oC = 44 mg/l
V = 10 l/min 0,4 ml H2O/min, i.e. 24 ml H2O/hod
600 ml/24 hod
+ hyperventilation !
+ fever !
Inspiration of dry air =
= losses 700-1000 ml/day
Aim: humidification to 100% r.h.
warming 37oC
27
CONSEQUENCES OF INSUFFICIENT
HUMIDIFICATION OF INSPIRATORY
GASES
• Losses of clear water from airway
• Concentration of secretions in airway
– failureof mucociliary transport
– airway obstruction
– development of atelektases
– airway infection
28
AIMS OF VENTILATORY
SUPPORT
• Bypassing of critical time during illness.
• Achievement of acceptible oxygenation
and ventilation paremeters.
• Elimination of side effects of artifitial
ventilation.
29
PHYSIOLOGICAL AIMS
1. Alveolar ventilation, paCO2, pH,
2. Oxygention support, paO2 above 8 kPa,
SaO2 above 90%, CaO2. Transport blood
capacity for oxygen (HB x SaO2 x C.O.)
3. Increase of lung volume (FRC) - PEEP
(against athelectases, improving of
oxygenation, ARDS, postoperative cases)
4. Decreasing work of respiratory muscles.
30
CLINICAL AIMS 1. Treatment and reverse of hypoxaemia
2. Treatment of acute respiratory acidosis
3. Solution od respiratory distress
4. Prophylaxy and treatment of atelectases
5. Help for respiratopry muscle weakness
6. Permision of pts. sedation / relaxtion
7. Systemic and / or myocardial decreasing of oxygen consumption (cardiogenic shock, ARDS)
8. Decreasing of ICP through paCO2.
9. Thoracic wall stabilisation (flail chest)
31
INDICATIONS FOR
ARTIFICIAL VENTILATION • Mechanics: f above 35/min, VC below 15
ml/kg, Insp.neg pressure below 25 cmH20.
• Oxygenation: paO2 below 70 mmHg at FiO2 0,4 by mask, AaDO2 above 350 mmHg at FiO2 1,0 or Qs/Qt above 20% (paO2/FiO2 below 200)
• Ventilation: Apnoe, paCO2 above 55 mmHg (except pat with chron. hyperkapnia), Vd/Vt above 0,60.
• Crucial are clinical findings!
32
PHYSIOLOGICAL AND
PATHOPHYSIOLOGICAL PRINCIPLES
OF ARTIFITIAL VENTILATION
• Airway securing during ventilation
• Apparatuses and equipment used
during ventilation
• Tactics of ventilation, ventilatory modes
• Monitoring of ventilation
• Complications of ventilation
• Weaning from ventilator
33
SOME PARAMETERS USED AS
INDICATORS OF ARTIFICIAL
VENTILATION
Parameter Physiologic
al values
Indications
for artificial
support
Vital capacity (ml/kg)
VD/VT
Inspiratory force (cmH2O)
Lung shunt (%) (Qs/Qt)
paO2 (kPa) (at FiO2 = 0,21)
p(A – a)DO2 (kPa) (at FiO2 = 0,21)
paO2/FiO2 (kPa)
paO2/FiO2 (mmHg)
paCO2 (kPa)
pH
Respiratory frequency
60 – 70
0,3
– (80 – 100)
5
13
1,3 – 4
> 40
> 300
5,3
7,35 – 7,45
12 – 18
10 – 15
0,6
< – 20
> 15
< 6,6
> 350
< 40
< 300
7,3 – 8
< 7,25
> 35 – 40
34
35
AYRE T-PIECE
FGF < 2 x MV
Face mask Tube - orotracheal
- nasotracheal
- tracheostomy
22/15 mm
22 mm (20 cm 80ml)
Atmosphere Inlet O2
36
• I:E Peak Flow %Ti
• Pause (%) Tip (s) from total respir. cycle
(S)CMV, Assist Control
37 Oh -
Firm
ent
38
BLOOD GASES INFLUENCE BY
ARTIFICIAL VENTILATION
paCO2
• alveolar
ventilation
(VT, f, Pinsp ...)
paO2
• FiO2
• mean Paw
(PEEP,
I:E Peak Flow %Ti,
Pause (%) Tip (s) )