Management of olv

1. DR THANSEEL T H

2.  PRETHORACOTOMY RESPIRATORY ASSESSMENT
 MANAGEMENT OF HYPOXIA DURING OLV

3. Pre-thoracotomy respiratory
assessment
 Respiratory mechanical function:predicted
postoperative (pp0)FEV1(most valid test)
Threshold for increased risk <30-40%
 Lung parenchymal function :ppo DLCO(Diffusing
capacity of CO)(most valid)
Threshold for increased risk <30-40%
 Cardiopumonary reserve :maximal o2 consumption
Threshold for increased risk <15 ml/kg/min

4. 1.Respirtory mechanics:ppo FEV1
ppoFEV1 %=Preoperative FEV1*(1-%Functional tissue
removed/100)
Total subsegments=42
Eg:for left lower lobectomy
Post op FEV1 Decrease =10/42=24%
Preop FEV1(Or DLCO) 75% Or 60%
For left lower lobectomy
Ppo FEV1 (Or DLCO) 57% 46%

6. 3.Cardiopulmonary interaction
 O2 consumption (vo2)-sitting quietly=3.5
ml/kg/min(1 MET)
 Climbing one flight (3 m or 10 feet)of stairs=4METS
 Preop vo2 max <15 ml/kg/min; morbidity /mortality
 Vo2 max <10ml/kg/min; morbidity /mortality
 Calculation of vo2 max in 6 min walk test -450 m
;450/30=15
 Two markers 10 m apart ;<250 m;vo2 <10

8. MANAGEMENT OF OLV
GOALS: To maximize atelectasis in the non- ventilated lung
to improve surgical access AND to avoid atelectasis in the
ventilated lung to optimize gas exchange
 Gas mixture in the non ventilated lug immediately before
OLV has effect on speed of collapse of this lung
 N2- low blood gas solubility, so air-O2 mixture will delay
collapse
 De-nitrogenate the operative lung by ventilating with
oxygen, before lung collapse

9.  N2O is more effective in speeding lung collapse , but
not preferred as most pts have bullae
 Atelectasis will develop in the dependent lung during
TLV before OLV
 Recruitment: Hold the lung at an end inspiratory
pressure of 20 cmH2O for 15- 20 seconds, soon after
start of OLV to decrease atelectasis imp. To prevent
desaturation

10. HYPOXEMIA DURING OLV
 No universally accepted figure for the safest lower limit of
oxygen saturation during OLV
 Saturation >90%( PaO2 > 60 mmHg) is accepted usually
 Brief periods of saturation in the high 80s – acceptable in
pts without significant co- morbidity
 Lowest acceptable saturation is higher in pts with organs
at risk of hypoxia or with limited O2 transport
 COPD patients desaturate more quickly on OLV, during
isovolemic hemodilution than normal pts
 Incidence of hypoxemia on OLV has decreased from 20-
25% to less than 5%: improved lung isolation techniques,
better anaesthetic agents and better understanding of the
pathophysiology of OLV

11. HYPOXEMIA DURING OLV contd..
 Goal during OLV: maximize PVR in the non ventilated
lung and minimize PVR in the ventilated lung
 PVR is correlated with lung volume in a hyperbolic
fashion
 PVR – lowest at FRC and increases as lung volume rises
or falls above or below FRC
 Maintain the ventilated lung as close as possible to
FRC while facilitating collapse of the non ventilated
lung to increase its PVR

12. Ventilation strategies -OLV
 7-8 ml/kg TLV & 5-6 ml/kg during OLV
 RR to target PaCO2 of 40-50/60 mmhg
 PEEP ;Normal lung,5 cmH2O;Obstructive lung,2-5
cmH2O;Restrictive lung,5-10 cmH2O
 Optimum FiO2 to maintain SpO2 >90%
 I:E ratio :normal ,1:2;obstructive lung,1:3-4;restrictive
lung 1:1
 Airway pressure :peak pressure <35 cmH2O
 Ventilation mode VCV or PCV

14. Who will develop hypoxia during
OLV
 Right sided thoracic surgery with right lung collapse
 Normal preop FEV1
 Low PaO2 during TLV
 Morbidly obese
 Previous contralateral lung sx
 Supine position
 High alveolar-arterial co2 gradient
 Patients on chronic vasodilator therapy

16. Management of hypoxia during
OLV

18. Pharmacologic manipulations
 The combination of NO ( 20 ppm) to the non
ventilated lung and an IV infusion of
PHENYLEPHRINE which enhances HPV has
been shown to restore PaO2 values during OLV
 INHALED EPOPROSTENOL (FLOLAN)
 Eliminate known potent vasodilators such as
nitroglycerin & halothane and large doses of other
volatile anaesthetics.