Weaning/HS (nurse)

This article is intended for students of secondary and higher vocational schools of nursing.

Explanation of terms

• Weaning – weaning, weaning.
• Discontinuation – termination, disconnection.
  • Successful disconnection – disconnection from the ventilator and spontaneous ventilation for at least 48 hours without the need for ventilatory support.
  • Successful extubation/decannulation.
  • Disconnection failure – necessity to restart the patient's UPV after previous disconnection within 48-72 hours of spontaneous ventilation.
    • On average in about 20% of patients, in patients with CNS impairment up to 33%.
• Simple disconnection – the patient tolerates the first SBT and is successfully extubated – 70% of patients.
• Difficulty Weaning – First Spontaneous Breathing Trial (SBT) failed, 2-3 SBTs required for successful weaning or within 7 days of first SBT.
• Prolonged disconnection - Failed at least 3 SBTs or lasted more than 7 days since the first SBT.
• Spontaneous Breathing Trial (SBT) - Spontaneous breathing on low pressure support (5-7 cm H 2 O)/ATC or Ayer 'T' at FiO 2 0.5.
  • Closer monitoring is needed for the first few minutes → most problems occur during this period.
  • The test lasts a minimum of 30 minutes, but no more than 120 minutes.

Method

1. 1. Income.
   2. Treatment of respiratory failure.
   3. Readiness for disconnection.
   4. Unplugging.
   5. SBT.
   6. Extubation.
   7. Release.

It is necessary to consider the termination of ventilation support from the moment of its initiation!

• • Switch to a mode with elements of spontaneous ventilation as soon as possible.
  • Support of spontaneous breathing activity (outside the critical phase).
  • Test the ability to breathe spontaneously.
  • Elimination/reduction of sedation.
  • Guidelines – protocol of the department.
  • Type of patients, experience, ventilator types, nurse/patient ratio.

Approaches

1. 1. Clinical approach - physician-directed approach .
      • The attending physician assesses the patient's condition and decides on the initiation of disconnection and the method of disconnection.
   2. Protocol (nurse) driven approach .
      • The procedure established by the protocol.
      • Routine disconnection "readiness" screening:
        • Nurse, respiratory technician, resident;
        • part of the office of the responsible doctor.

Ayer's T

• • Minimum resistance.
  • Excellent tolerance test - 30'-120'.
  • Absence of ventilator monitoring.
  • Absence of backup ventilation.
  • The need for supervision.
  • Very fast transition to spontaneous breathing.

Weaning via ASB

• • The patient regulates f, Vi and VT himself.
  • Fan synchronization, WOB reduction.
  • PEEPint compensation in COPD (COPD).
  • Optimal f 25–30/m.
  • Unsuitable unstable respiratory drive.
• Tachypnea (autoPEEP).
  • Auto-trigger (leak).
  • Apnoeic pauses during excessive inspiratory pressure!!!

Risks of extending UPV

• • Infection (VAP).
  • UPV lung damage.
  • Need for sedation.
  • Respiratory tract injury.
  • Costs.

Risks of premature termination of UPV

• • Loss of control of airway patency.
  • Cardiovascular stress - circulatory failure.
  • Insufficient gas exchange.
  • Excessive strain and fatigue of respiratory muscles.

Reintubation

• • Reintubation is an independent risk factor for the development of nosocomial pneumonia and higher mortality.
  • Internal and neurological patients → longer hospitalization, more frequent tracheostomy, higher mortality.
  • Positive fluid balance.
  • Positive culture of tracheobronchial secretions in patients with COPD within 72h after extubation.
  • Amount of sputum - suction > 2 x hour, sputum > 2.5 ml/h.
  • Tidal volumes – Vt >4–5 ml/kg, df < 30/min.

Cause of disconnection failure

• • Respiratory tract: Aspiration (gastric nutrition, suction NG body position), secretion in the respiratory tract, swelling of the respiratory tract.
  • Outside the respiratory tract: Respiratory insufficiency due to other causes, cardiac failure, impaired consciousness, uncooperative patient.

Failure factors

• Decreased activity of the respiratory center: Lack of sleep, general fatigue, encephalopathy of various etiology, excessive sedation, metabolic alkalosis (compensation of chronic RAC).
• Increased work of breathing: Hyperventilation - CNS damage, increased dead space ventilation, withdrawal syndrome; difficult expiration – PEEPi,airway obstruction, COPD; inappropriate ventilation mode; increased production of CO 2 – increased intake of energy (sugars), hypermetabolism, hyperthermia; raised diaphragm – high intra-abdominal pressure.
• Central and peripheral nervous system - ventilatory failure.
• Respiratory system: Oxygenation failure - cause at the level of blood gas exchange through the alveolocapillary membrane (pneumonia, fibrosis,...); ventilation failure – malfunction of the ventilation pump.
• Cardiovascular system: Changes in intrathoracic pressure during disconnection; increased respiratory muscle demands; heart failure; imbalance between the supply and consumption of oxygen by the myocardium - myocardial ischemia.
• Psychological cause.
• Weakness and fatigue of respiratory muscles.
• Malnutrition, respiratory muscle catabolism.
• Muscular atrophy, neuromyopathy of critically ill patients.
• Mineral breakdown (hypophosphatemia, hypomagnesemia).
• Muscle ischemia during excessive exercise.
• Paresis of the phrenic nerve.
• Polyneuritis, myasthenia.
• muscle relaxation.

Clinical monitoring

• • Subjective shortness of breath.
  • Involvement of auxiliary respiratory muscles.
  • Perspiration.
  • Tachycardia.
  • Abdominal paradoxical breathing.
  • Subjective discomfort.

Disconnect criteria

1. 1. Adequate oxygenation (more permissive).
      • PaO 2 /FiO 2 > 150 to 200 mm Hg; PEEP < 5–8 cm H 2 O; FiO 2 < 0.4 to 0.5; pH > 7.25.
   2. Hemodynamic stability.
      • Absence of acute myocardial ischemia.
      • Absence of significant hypotension (0/ or only low-dose dopamine / dobutamine <5μg/kg/min), heart rate <140/min.
   3. Improvement of clinical condition.
      • Afebrile < 38 °C, no RAc and Ral, Hgb 80–100 g/l, GCS > 13, no continuous sedation, stable metabolic conditions (electrolytes).

Prerequisites for successful extubation

• • Airway patency.
  • Reflexes of the cranial nerves (coughing, swallowing, expectoration).
  • Absence of excessive secretion from the respiratory tract.
  • Consciousness (minimizing sedation, responding to challenge).
  • No risk of post-extubation stridor.
  • Test for determining the risk of post-extubation airway obstruction (air leakage around the deflated cuff of the tracheal tube).

SBT failure procedure

• • Connection to a ventilator (adequate ventilation support),
  • The need to identify the cause of the failure.
  • Repetition of SBT is recommended no earlier than in 24 hours, performing several times a day is not demonstrably associated with shortening the duration of ventilatory support.
  • In selected situations where SBT fails due to a quickly correctable cause, it is considered to repeat it earlier.
  • Gradual reduction of ventilatory support.

Disconnection tolerance criteria

• • RR > 35/min, SpO 2 < 88%, PaO 2 60 mmHg, VT below 4 ml/kg.
  • Tachycardia.
    • Lower values ​​can be tolerated for a maximum of minutes.
• Signs of respiratory distress (at least 2):
  • • significant involvement of auxiliary respiratory muscles;
    • paradoxical abdominal breathing;
    • perspiration;
    • subjective feeling of dyspnea.

Patients who are difficult to detach

• • Failure after 14-21 days of repeated attempts.
  • Irreversible addiction (neurological dg.1–5%).
  • High spinal cord lesion, ALS,...

→

• • Freight patients.
  • Higher morbidity & mortality (only 25% discharge).
  • Specialized rehab centers.
  • At least a 3-month limit to declare permanent dependence.

Links

• Artificial pulmonary ventilation/SŠ (nurse)

Source

• MUDR. VOJTÍŠEK, Petr. Weaning [lecture for subject Modul UPV, specialization Sestra pro intenzivní péči – postgraduální studium, Vyšší odborná škola zdravotnická škola Střední a vyšší zdravotnická škola Ústí nad Labem]. Ústí nad Labem. 16.12. 2012. 

• DOSTÁL, Pavel, et al. Základy umělé plicní ventilace. 2., rozšířené edition. Praha : Maxdorf Jessenius, 2005. ISBN 80-7345-059-3.