very important

1. DR.BIKAL LAMICHHANE
INTERNAL MEDICINE
NAMS
INVASIVE VENTILATION-
INDICATIONS AND WEANING

2. INVASIVE VENTILATION
 Invasive mechanical ventilation is defined as the delivery of positive
pressure to the lungs via an endotracheal or tracheostomy tube.
 During mechanical ventilation, a predetermined mixture of air (ie,
oxygen and other gases) is forced into the central airways and then
into the alveoli.
 As the lungs inflate, the intra-alveolar pressure increases
termination signal (usually flow or pressure) eventually causes the
ventilator to stop forcing air into the central airways  central airway
pressure decreases Expiration follows passively, with air flowing
from the higher pressure alveoli to the lower pressure central
airways.

5. INDICATIONS :

6. INDICATIONS:-

8. General Care Of Mechanically Ventilated
Patients
 Sedation, analgesia, and delirium management
 Hemodynamic monitoring
 Nutritional support

 Glycemic control
 Measures to prevent ventilator-associated pneumonia
 Venous thromboembolism prophylaxis
 Gastrointestinal prophylaxis for stress ulcers
 Venous or arterial access (eg. central venous access)

9.  PATHOPHYSIOLOGIC CONSEQUENCES OF MECHANICAL VENTILATION :
 Pulmonary Effects:
 Barotrauma : pneumothorax, subcutaneous emphysema, pneumomediastinum, and
pneumoperitoneum.
 Ventilator-associated lung injury
 Auto-PEEP - Intrinsic PEEP
 Heterogeneous ventilation
 Ventilation/perfusion mismatch - worsen dead space but improve shunt.
 Diaphragm : Diaphragmatic muscle atrophy, a phenomenon called ventilator induced
diaphragmatic dysfunction(VIDD)
 Respiratory muscles : Respiratory muscle atrophy in (VIDD).
 Mucociliary motility : Impair mucociliary motility  retention of secretions and
pneumonia.

10.  Hemodynamics — Decreases cardiac output  hypotension.
 Gastrointestinal :Gastrointestinal bleeding due to stress ulceration
 Renal : Acute renal failure
 Central nervous system :Increases intracranial pressure (ICP)
 Weakness :Systemic muscular weakness
 Immune system :Induce inflammation
 Sleep : Disordered sleep "atypical sleep" or "pathological
wakefulness"

11. Discontinuing Mechanical Ventilation
 Three step process:-
Readiness testing : During readiness testing , the clinical criteria
and weaning predictors are evaluated to determine whether a
patient is ready to begin weaning.
Weaning : Weaning is the process of decreasing ventilator support
and allowing patients to assume a greater proportion of their
ventilation.
Extubation : considered once the patient demonstrates the ability to
breathe without the ventilator and both airway patency and airway

12. Weaning :-
 Weaning is the process of decreasing ventilator support and allowing patients
to assume a greater proportion of their ventilation.
 It may involve either an immediate shift from full ventilatory support to a period
of breathing without assistance from the ventilator (ie, a spontaneous
breathing trial [SBT]) or a gradual reduction in the amount of ventilator
support.
 Simple wean – Patients are considered to have undergone a simple wean when
they pass their first weaning trial, typically a spontaneous breathing trial (SBT).
 Difficult-to-wean – Patients are considered difficult-to-wean if they fail their first
SBT and then require up to three SBTs or seven days to pass an SBT
 Prolonged weaning – Patients are considered to have undergone prolonged
weaning if they fail at least three SBTs or require more than seven days to pass an
SBT

13.  Clinical evidence :

14. CHOOSING A WEANING METHOD
 For patients who have been intubated for more than 24 hours and have
been deemed as ready to wean  weaning trial.
 Preferred method : Daily spontaneous breathing trials (SBTs) with
inspiratory pressure support : efficient, safe, and effective
 Older methods : progressive decreases in the level of pressure support
during pressure support ventilation (PSV) and progressive decreases in
the number of ventilator-assisted breaths during intermittent mandatory
ventilation (IMV).
 Newer weaning methods : computer-driven automated PSV weaning
and early extubation with immediate use of post extubation noninvasive
ventilation (NIV)

15. Daily spontaneous breathing trials (SBTs)
 For patients with acute respiratory failure on mechanical ventilation - SBT preferred
as the initial weaning strategy.
 Patient breaths spontaneously through the endotracheal tube (ETT) for a set
period of time, typically 30 minutes to two hours.
 Choosing ventilatory support - SBT with some form of ventilatory support is
preferred (eg, low-level PSV, automatic tube compensation [ATC] or continuous
positive airway pressure [CPAP; eg, 5 cm H2O]) rather than no ventilatory support
(eg, using a T-piece).
 Recommendations of the American College of Chest Physicians/American
Thoracic Society  PSV (eg, inspiratory pressure augmentation of 5 to 8 cm
H2O), When using PSV-SBT, the positive end-expiratory pressure (PEEP) remains
at 5 cm H2O and the fraction of inspired oxygen (FiO2) at 0.4 or lower.
 T-piece may be more appropriate in patients at risk for acute cardiogenic
pulmonary edema and patients with acute hypercapnia from obstructive lung
disease.

17. Trial duration :-
 Duration of MV <24 hours : Generally do not require an SBT,
although a 30-minute SBT is unlikely to be harmful (eg, following
surgery or for airway protection).
 Duration of MV 1 to <10 days : Initial SBT of 30 minutes duration is
generally sufficient.
 Duration of MV ≥10 days : Trials of 30 minutes may still be sufficient
.However, in many cases trials extended for up to two hours.
 Subsequent SBTs after failed initial SBT : Longer than 30 minutes,
up to two hours

18.  Alternative methods : no longer typically used as an initial weaning strategy.
 Pressure support weaning : Pressure support may be initially set between 12
and 18 cm H2O (to target a spontaneous respiratory rate ≤25 breaths per
minute). PSV is then reduced, if possible, by 2 to 4 cm H2O at least twice a day
until a pressure support of 5 to 8 cm H2O is reached for two hours or more (ie,
typically over a 24 hour period). More rapid reductions in PSV weaning have
also been described. PEEP of up to 4 or 5 cm H2O is usually applied.
 Intermittent mandatory ventilation : Ventilator rate may be initially set at 8 to
12 breaths per minute. The IMV rates is then decreased usually by 2 to 4
breaths per minute, if possible, at least twice a day until four or five breaths per
minute or less is reached for two hours or more.
 Extubation to noninvasive ventilation — For selected patients who fail the
initial SBT (eg, patients with COPD or chronic hypercapnic respiratory failure).

19.  ASSESSMENT OF WEANING SUCCESS OR FAILURE
 Clinical assessment :
 Monitor vital signs and ventilator parameters such as the tidal volume and
respiratory rate (ie, minute ventilation).
 Assess for respiratory distress and mental status changes, and if alert and
responsive, ask about the presence of dyspnea and chest pain.
 Telemetry monitors : ST changes
 Electrocardiography to look for cardiac ischemia.
 Arterial or venous blood gas (ABG, VBG) in those at risk of developing acute
hypercapnia during weaning (eg, patients with chronic obstructive pulmonary
disease [COPD], patients who underwent prolonged mechanical ventilation,
patients with known or suspected neuromuscular weakness).

21.  Weaning success :
 When a patient successfully passes a weaning trial, they should be
evaluated for safety of extubation by assessment of the volume of
respiratory secretions as well as airway patency and protection (ie,
has a sufficient cough and adequate level of consciousness)
 Weaning failure :
 Patients who fail a weaning trial should be placed back on their
previous ventilator settings. No further attempts at weaning are
typically made for another 24 hours.

22. Etiologies of the difficult-to-wean patient

23. Etiologies of the difficult-to-wean patient

24. THANK YOU