Post on 13-Jan-2017
WEANING AND DISCONTINUATIO
N Presented byAnn Mary Jose,
OBJECTIVES Rationale for weaning
Predictors of Weaning success or failure
Methods of weaning
Weaning failure
WEANING The transition process from total ventilatory support to
spontaneous breathing trial.
This period may take many forms ranging from abrupt withdrawal to gradual withdrawal from
ventilatory support.
CATEGORIES• First SBT trial successful, extubation successful.
SIMPLE WEANING
• Fails first SBT, requires upto 3 SBTs before successful (7 days or less from 1st SBT to successful SBT)
DIFFICULT WEANING
• Fails atleast 3 SBTs or requires > 7 days from 1st SBT to successful SBT
PROLONGED WEANING
WHEN SHOULD WEANING COMMENCE ?• Evaluation of weanability should commence with decision to intubate, ventilate.
• Patient should be tested for reduced support when it is safe.
• Physicians must relay on clinical judgement.
• Consider when the reason for IPPV is stabilized and the patient is improving and haemodynamically stable
• Daily screening may reduce the duration of MV and ICU cost
DOUBLE EDGED SWORD !!!! Unnecessary delays in this discontinuation process increase the complication rate from mechanical ventilation (e.g., pneumonia, airway trauma) as well as the cost
!! Premature discontinuation carries its own set of problems, including difficulty in re-establishing artificial airways and compromised gas exchange.
DAILY SCREENING• Resolution/improvement of patient’s underlying problem
• Patient able to initiate an inspiratory effort.
• Normal state of consciousness
• Absence of fever, temperature < 38C
• Correction of metabolic and electrolyte disorders
• Adequate hemoglobin concentration, > 8-10 g/dl
PHYSIOLOGICAL PARAMETERS
Ventilatory performance and muscle strength
VC > 15mL/kg
VE < 10 to 15 l/min
VT > 4 to 6 ml/kg
f < 35 breaths per minf/VT < 60 to105 breaths/min/L
PImax < -20 to -30 cm H2O
Measure of drive to breath
P0.1 > -6cm H20
Measure and estimation of WOB
WOB < 8J/L
Cdyn > 25mL/cm H2O
VD/VT < 0.6
CROP index > 13 mL/breaths/min
Measurement of adequacy of oxygenationPaO2 > 60 mm Hg
PEEP < 5 to 8 cm H2OPaO2/FiO2 > 250 mm
HgPaO2/PAO2 > 0.47
P(A-a)O2 < 350 mm Hg
%QS/QT < 20% to 30%
Patients receiving MV for respiratory failure should undergo a formal assessment of discontinuation potential if the criteria are satisfied.
Reversal of cause, adequate oxygenation, haemodynamic stability, capability to initiate
respiratory effort. The decision must be individualized.
Search for all the causes that may contribute to ventilator dependence in all patients with longer than 24hrs of MV support, particularly who has fail attempts. Reversing all possible causes should be an integral part of discontinuation process.
PREDICTORS OF THE OUTCOME OF WEANING
Patient parameters Awake, alert and cooperative Haemodynamically stable RR < 30/min No effect of sedation/neuromuscular blockade Minimal secretions Nutritional status good
Burton GG Respir Care 1997, Caruso P 1999 Chest Girault C. 1994 Monaldi Arch Chest Dis, TobinMJ. 1990 Eur Respir J, Yang
KL.1991 N Engl J Med
Ventilator parameters Spontaneous TV > 5 - 8 ml/kg , VC > 10 - 15 ml/kg , PEEP requirement < 5 mm of H2O
Static compliance > 30 ml/cm of H2O MV < 10 L VD/VT < 60 %
MIP < -30 cm H2O NIF
Burton GG Respir Care 1997, Caruso P 1999 Chest Girault C. 1994 Monaldi Arch Chest Dis, TobinMJ. 1990 Eur
Respir J, Yang KL.1991 N Engl J Med
Oxygenation criteria PaCO2 < 50 mm of Hg with Normal pH PaO2 > 60 at FiO2 0.4 or less SaO2 > 90 % at FiO2 0.4 or less PaO2/FiO2 > 200 Qs/QT < 20 % P(A-a)O2 < 350 mm of Hg at FiO2 of 1.0Burton GG Respir Care 1997, Caruso P 1999 Chest
Girault C. 1994 Monaldi Arch Chest Dis, TobinMJ. 1990 Eur Respir J, Yang KL.1991 N Engl J Med
None of the variables demonstrate more
than modest accuracy in predicting weaning outcome
The removal of the artificial airway from a patient who has successfully been discontinued from ventilatory support should be based on assessment of airway patency and the ability of the patient to protect the airway.
PARAMETERS THAT ASSESS AIRWAY PATENCY AND PROTECTION
1. Maximal expiratory pressure
2. Peak expiratory flow rate
3. Cough strength
4. Secretion volume
5. Suctioning frequency
6. Cuff leak test
7. Neurological function (GCS)
METHODS OF WEANING
Spontaneous
breathing with t-
piece
SIMV
Newer Modes
PSV
GRADUAL V/S SUDDEN
WEANING ??? No data available Most trials have used
sudden weaning using Spontaneous breathing trial with T-piece, PSV or CPAP
However if a patient fails recurrent weaning attempts gradual weaning strategy is advocated
Respir Care 2002; 47: 69-90
SPONTANEOUS BREATHING TRIAL• Communicate with patient, weaning is about to begin, allow patient to express fear whenever possible
• Obtain baseline value and monitoring clinical parameters; vital signs, distress, gas exchange, arrhythmia
• Ensure a calm atmosphere, avoid sedation
• Fit T-tube with adequate flow, observe for 2 hrs.
Esteban et al compared a 30 min to a 120min T-piece trial
No reported difference in the rate of re-intubation
between groups.
Patients who were randomized to the
shorter T-piece trial benefited from
statistically significant reductions in ICU and
hospital lengths of stay (2 days and 5 days
shorter, respectively)
The criteria to assess patient tolerance during SBTs are respiratory pattern, gas exchange, hemodynamics stability and patient comfort. The tolerance of SBTs lasting 30 to 120 minutes should prompt for permanent ventilator discontinuation.
PRESSURE SUPPORT PROTOCOL
Esteban et al compared 2-h trials of unassisted breathing
using PS of 7 cm H2O v/s a T-pieceA smaller proportion of patients in the PS group
(14%) failed to tolerate the weaning and to achieve
extubation at the end of the 2-h trial than in the T-pieceReintubation rates were similar
A superior weaning technique among the threemost popular modes, T-piece, pressure support
ventilation, or synchronized intermittent mandatory ventilation cannot be identified
SIMV may lead to a longer duration of the weaning process than either T-piece or PSV
The most effective mode of ventilation for weaning still needs to be determined and
more work is required in this area.
FAILED TO WEAN
Patients receiving MV who fail an SBT should have the cause determined. Once causes are corrected, and if the patient still meets the criteria , subsequent SBTs
should be performed every 24 hours.
Early detection
Record vs. physical
exam
Obtain an ABG if
possible
Put back previous settings
Identify causes
SIGNS AND SYMPTOMS OF WEANING FAILURE
Subjective Indices
• Agitation and anxiety• Diaphoresis • Cyanosis • Accessory muscle use• Facial sign of distress• Dyspnea
Objective Measurements• PaO2 ≤50-60 mmHg on FiO2 ≥ 0.5
• SaO2 < 90%• PaCO2 > 50mm Hg• pH < 7.3• f/Vt > 105 breaths/min/L• RR > 35bpm• SBP ≥ 180mmHg or increase of
≥ 20%• SBP < 90mmHg• Cardiac arrhythmias
RR > 10 breaths/min
HR > 20 beats/minSPB > 30 mmHg
Associated with intrinsic lung disease
Associated with prolonged critical illness
Incidence approximately 20%
Increased risk in patient with longer duration of mechanical ventilation
Increased risk of complications, mortality
Patients receiving MV for respiratory failure who fail an SBT should receive a stable, non fatiguing, comfortable form of ventilatory
support.
Rest 24 hours
Correct the causes
Retry weaning
Retry with gradual modes
Tracheostomy long term ventilation
ROLE OF TRACHEOSTOMY
Click icon to add picture
Tracheostomy should be considered after period of stabilization on the ventilator when it becomes apparent that the patient will require prolonged MV. Tracheostomy should be performed when the patient appears likely to gain one or more benefits from the procedure
• Improved patient comfort• More effective airway suctioning• Decreased airway resistance • Enhanced patient mobility• Increased opportunities for articulated speech• Ability to eat orally, a more secure airway • Accelerated weaning from mechanical ventilation• Ability to transfer ventilator-dependent patients from ICU
Unless there is evidence for clearly irreversible disease, a patient requiring prolonged MV should not be considered permanently ventilator-dependent until 3 months of weaning attempts have failed.
SUMMARY• The ventilator discontinuation process is a critical component of ICU care.
• Daily wean screen and subsequent SBT should be done in all patients recovering from respiratory failure.
• Early extubation with backup ventilation of NIPPV is usefull especially in COPD
• Role of newer modes unclear – require more studies.
•Managing the patients who fails the SBT - determine the reasons for failure.
REFERENCE1. Neil R. Maclntyre, Mechanical Ventilation: 2nd edition; Chapter 18,
Discontinuing Mechanical Ventilation; pg.no. 317-322.
2. Lynelle N. B. Pierce, Management of the mechanically ventilated Patient: 2nd edition; Chapter 11, Weaning from Mechanical Ventilation; pg.no. 378-398.
3. Susan P. Pilbeam, Mechanical Ventilation: 5th edition; Part 7: Discontinuation from Ventilation and Long term Ventilation; pg.no. 402 – 452
THANK YOU