Respiratory monitoring / Safe weaning of respiratory support

Transcription

1 Respiratory monitoring / Safe weaning of respiratory support Athavudh Deesomchok, MD Pulmonary, Cri9cal care and Allergy Medicine CMU CVT Short course 2013

2 Post- cardiac surgical care Opera9ng room ICU Complica:ons Step down unit Surgical ward Home discharge

3 Postopera:ve pulmonary complica:ons Atelectasis Infec9on: tracheobronchi9s, pneumonia Exacerba9on of underlying chronic lung disease Venous thromboembolism Prolonged mechanical ven9la9on Others: Acute lung injury/ards, phrenic nerve damage, pleural effusion, sternal wound infec9on (medias9ni9s), etc.

4 Incidence of pulmonary complica:ons in cardiac surgical pa:ents Period Pa:ents (n) Median :me to extuba- :on MV > 72 h (%) Reintu- ba:on (%) Tracheo stomy (%) In- hospital mortali- ty (%) 11, d ,863 2 d , h Kaplan s Cardiac Anesthesia 6 th ed p.1047

5 Risk factors for delayed tracheal extuba:on (> 10 hr) Increased age Female Postopera9ve use of intra- aor9c balloon pump Inotropes Bleeding Atrial arrhythmia Risk factors for prolonged ICU LOS (> 48 hr) Those of delayed tracheal extuba9on plus Preopera9ve MI Postopera9ve renal insufficiency Wong DT, et al. Anesthesiology 1999; 91:

6 Monitoring during mechanical ven:la:on

7 Ven:latory effects arer cardiothoracic surgery Hypoxic pulmonary vasoconstric9on (inhala9on anesthe9cs) Blun9ng of hypoxemic and hypercapnic ven9latory drive (IV narco9cs) Decrease lung volume Atelectasis Diaphragma9c dysfunc9on (phrenic n. injury)

8 Monitoring during mechanical ven:la:on Signs of respiratory distress Level of consciousness Gas exchange (ABGs, pulse oximetry, capnography) Lung mechanics Ability to cough and deep breath Fluid balance and hemodynamics

9 Signs of respiratory distress Tachypnea Tachycardia or arrhythmia Hypo- or Hypertension Diaphoresis Retrac9on of suprasternal, supraclavicular, intercostal space Nasal flaring Use of accessory muscles and abdominal paradox

10 Arterial blood gases Gas exchange Oxygena9on, alveolar ven9la9on, acid- base Pulse oximetry Oxygen satura9on of arterial blood (SpO 2 ) Capnography: CO 2 in expired gas (PETCO 2 ) To es9mate PaCO 2, To detect changes in pulmonary blood flow or dead space ven9la9on

11 Pulse oximetry (SpO 2 = [oxyhb/(oxyhb+deoxyhb)] x 100 Inaccurate reading: mo9on ar9fact, abnormal Hb (COHb, methb), intravascular dyes (methylene blue), low perfusion state, skin pigmenta9on, nail polish, low SpO 2, Insensi9ve to changes in PaO 2

12 Capnography Decreased PETCO 2 Increased PETCO 2 Increased CO 2 produc9on: fever, sepsis, bicarbonate administra9on, increased metabolic rate, seizure Decreased alveolar ven9la9on: RC depression, muscle paralysis, hypoven9la9on, COPD Equipment malfunc9on: rebreathing, exhausted CO 2 absorber, leak in ven9lator circuit Decreased CO 2 produc9on: hypothermia, pulmonary hypoperfusion, cardiac arrest, pulmonary embolism, pulmonary hymorrhage, hypotension Increased alveolar ven9la9on: hyperven9la9on Equipment malfunc9on: ven9lator disconnect, esophageal intuba9on, complete airway obstruc9on, poor sampling, leak around ET tube cuff

13 Capnograph

14 Lung mechanics Compliance: sta9c, dynamic Resistance Ven9lator waveform

15 Resis9ve proper9es! Respiratory system compliance! Inspiratory pause > 0.5 s Sta:c respiratory system compliance = V T / (P plat PEEP) Airway resistance = (PIP P plat ) / Flow

16 High Ppeak due to high airway resistance (w/o propor:onal Pplat) Coughing Mucus plug Bi9ng on ET tube Bronchospasm Ven9lator circuit obstructed by condensed water High Ppeak due to low sta:c compliance (with propor:onal Pplat) Tension pneumothorax Pulmonary edema ET 9p in right main bronchus Inverse I:E ra9o Resist posi9ve pressure breath Excessive V T

17 Flow starva9on Auto- PEEP

18 Weaning and Extuba:on

19 Process of weaning Ven9lator support Readiness for weaning Spontaneous breathing trial (SBT) Extuba9on

20 Ven:la:on management goal during the ini:al trial of weaning from extuba:on Ini:al ven:la:on parameters: V T 8-10 ml/kg, RR 10-12/min, PEEP 5 cmh 2 O Maintain ABGs: ph , PaCO mmhg, PaO 2 > 90 mmhg, SaO 2 > 95% Extuba:on criteria: ABGs as above, awake and alert, stable hemodynamics, no ac9ve bleeding (< 400 ml/ 2 hr), Temp > 36 o C, return of muscle strength (head lim > 5 s, strong handgrip) Kaplan s cardiac anesthesia 6 th ed, 2011.

21 Readiness to wean Clinical assessment Adequate cough Absence of excessive tracheobronchial secre9on Resolu9on of disease acute phase Eur Respir J 2007;29:

22 Objec:ve measurement Clinical stability Cardiovascular: HR < 140/min, SBP mmhg, no or minimal vasopressors Metabolic Adequate oxygena:on: SaO 2 > 90% on FiO 2 < 0.4 (or P/F ra9o > 150), PEEP < 8 cmh 2 O Adequate pulmonary func:on: RR < 35/min, MIP < cmh2o, V T > 5 ml/kg, VC > 10 ml/kg, f/v T < 105, no significant respiratory acidosis Adequate menta:on: no seda9on or adequate menta9on on seda9on (or stable neurologic pa9ent) Eur Respir J 2007;29:

23 Spontaneous breathing trial (SBT) CPAP 5 cmh 2 O, PS 5-7 cmh 2 O, or T- piece Assessment of pa9ent tolerance Respiratory papern Adequacy of gas exchange Hemodynamic stability Subjec9ve comfort Tolerance of SBT las9ng min è consider permanent ven9lator discon9nua9on (success > 77%)

24 Failure criteria of SBT Clinical assessment Agita9on and anxiety Depressed mental status Diaphoresis Evidence of increasing effort: increased accessory muscle ac9vity, facial signs of distress, dyspnea Objec:ve measurement PaO 2 < mmhg on FiO 2 > 0.5 or SaO 2 < 90% PaCO 2 > 50 mmhg or increase > 6 mmhg ph < 7.32 or decrease > 0.07 f/vt > 105 RR > 35/min or increase > 50% HR > 140/min or increase > 20% SBP > 180 mmhg or increase > 20% SBP < 90 mmhg Cardiac arrhythmias Eur Respir J 2007;29:

25 Success of extuba:on Cuff leak > 110 ml Capacity to protect airway and to expel secre9on with an effec9ve cough Absence of excessive secre9on or frequency of airway suc9oning Peak cough flow > 160 L/min Chest 2001;120:375S- 395S.

26 ICU LOS, MV 9me 28 day mortality, HAP, reintuba9on J Med Assoc Thai 2005;88:

27 Hemodynamic effects of mechanical insuffla:on RV preload Pulmonary vascular transit 9me ( 3-5 beats) pleural pressure RV ejec9on LV preload transpulmonary pressure RV amerload LV amerload LV ejec9on LV ejec9on LV preload Inspira:on Crit Care 2000;4: Expira:on

28 Mechanical ven:la:on in heart failure LV dysfunc9on with MI or severe CHF, é LV preload, pulmonary edema, ê cardiac output, hypoxemia and é WOB In the presence of LV dysfunc9on with é preload, PEEP elevates intrathoracic pressure ê venous return (ê preload) PEEP may increase PVR (é RV amerload and ê lem heart filling) PEEP may improve LV amerload

29 Noninvasive ven:la:on To prevent and treat acute respiratory failure following endotracheal extuba9on CPAP (con9nuous posi9ve airway pressure) NPPV (non- invasive posi9ve pressure ven9la9on)

30 Aims of non- invasive ven:la:on To par9ally compensate for affected respiratory func9on by reducing the work of breathing To improve alveolar recruitment with more efficient gas exchange To reduce LV amerload increasing CO and improving hemodynamics

31 Indica:ons for non- invasive ven:la:on in post- anesthe:c care unit (PACU) Prophylac:c Preven9on of airway obstruc9on (OSA, tracheomalacia) Preven9on of atelectasis in high risk surgical pa9ents (bariatric surgery) Therapeu:c Postopera9ve hypoxemia (atelectasis, mucus plugging) Postopera9ve hypercarbia or respiratory weakness Postobstruc9ve pulmonary edema Anesthesiology Clin 2012;32:

32 NIV in postop pa:ents: A systema:c review Intensive Care Med 2011;37:

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