Ventilator weaning By. Mr. Kim Monteiro. R.N. B.Sc N Dual role nurse practitioner
Respiratory weaning :- The process of withdrawing the patient from dependence on the ventilator.
It takes place in three stages: <ul><li>The patient is gradually removed :- </li></ul><ul><li>from the ventilator, </li></ul><ul><li>from the tube, </li></ul><ul><li>finally from oxygen. </li></ul>
Weaning is started when the patient is recovering from the acute stage of medical and surgical problems and when the cause of respiratory failure is sufficiently reversed . When is weaning initiated ?????
Criteria for Weaning Careful assessment is required to determine whether the patient is ready to be removed from mechanical ventilation.
Weaning indices to be assessed:- • Vital capacity : the amount of air expired after maximum inspiration. Used to assess the patient’s ability to take deep breaths. Vital capacity should be 10 to 15 mL/kg to meet the criteria for weaning. • Maximum inspiratory pressure (MIP): used to assess the patient’s respiratory muscle strength. It is also known as negative inspiratory pressure and should be at least −20 cm H2O. • Tidal volume : volume of air that is inhaled or exhaled from the lungs during an effortless breath. It is normally 7 to9 mL/kg. • Minute ventilation : equal to the respiratory rate multiplied by tidal volume. Normal is about 6 L/min. • Rapid/shallow breathing index : used to assess the breathing pattern and is calculated by dividing the respiratory rate by tidal volume. Patients with indices below 100 breaths/min/L are more likely to be successful at weaning .
Other indices :- <ul><li>a PaO2 of greater than 60 mm Hg with an FiO2 of less than 40%. </li></ul><ul><li>Stable vital signs and arterial blood gases </li></ul>
Patient Preparation Physiological consideration :- #The nurse must consider the patient as a whole, taking into account factors that impair the delivery of oxygen and elimination of carbon dioxide as well as those that increase oxygen demand (sepsis, seizures, thyroid imbalances) or decrease the patient’s overall strength (nutrition,neuromuscular disease). Psychological consideration:- # The nurse explains what will happen during weaning and what role the patient will play in the procedure. The nurse emphasizes that someone will be with or near the patient at all times, and answers any questions simply and concisely.
Proper preparation of the patient can reduce the weaning time
Assist–control mode:- <ul><li>Assist–control may be used as the resting mode for patients undergoing weaning trials. </li></ul><ul><li>This mode provides full ventilatory support by delivering a preset tidal volume and respiratory rate; if the patient takes a breath, the ventilator delivers the preset volume. The cycle does not adapt to the patient’s spontaneous efforts. </li></ul><ul><li>The nurse assesses patients being weaned on this mode for the following signs of distress: rapid shallow breathing, use of accessory muscles, reduced level of consciousness, increase in carbon dioxide levels, decrease in oxygen saturations, and tachycardia. </li></ul>
Intermittent mandatory ventilation (IMV) <ul><li>The patient on intermittent mandatory ventilation (IMV) can increase the respiratory rate, but each spontaneous breath receives only the tidal volume the patient generates. </li></ul><ul><li>Mechanical breaths are delivered at preset intervals and a preselected tidal volume, regardless of the patient’s efforts. </li></ul><ul><li>IMV allows patients to use their own muscles of ventilation to help prevent muscle atrophy. </li></ul><ul><li>IMV lowers mean airway pressure, which can assist in preventing barotraumas . </li></ul>
Synchronized intermittent mandatory ventilation (SIMV) <ul><li>Synchronized intermittent mandatory ventilation (SIMV) delivers a preset tidal volume and number of breaths per minute. </li></ul><ul><li>Between ventilator-delivered breaths, the patient can breathe spontaneously with no assistance from the ventilator on those extra breaths. </li></ul><ul><li>As the patient’s ability to breathe spontaneously increases, the preset number of ventilator breaths is decreased and the patient does more of the work of breathing . </li></ul><ul><li>SIMV is indicated if the patient satisfies all the criteria for weaning but cannot sustain adequate spontaneous ventilation for long period. </li></ul>
NURSING INTERVENTIONS IN IMV & SIMV:- <ul><li>Nursing interventions for both of these include:- </li></ul><ul><li>1. Monitoring progress by recording respiratory rate, minute volume, spontaneous and machine-generated tidal volume, FiO2, </li></ul><ul><li>2. Arterial blood gas levels. </li></ul>
PSV+SIMV <ul><li>The pressure support ventilation (PSV) mode assists SIMV by applying a pressure plateau to the airway throughout the patient triggered inspiration to decrease resistance by the tracheal tube and ventilator tubing. Pressure support is reduced gradually as the </li></ul><ul><li>patient’s strength increases. </li></ul>
NURSES ROLE IN PSV <ul><li>The nurse must closely observe the patient’s respiratory rate and tidal volumes on initiation of PSV. </li></ul><ul><li>It may be necessary to adjust the pressure support to avoid tachypnea or large tidal volumes. </li></ul>
The proportional assist ventilation (PAV) mode <ul><li>The proportional assist ventilation (PAV) mode of partial ventilatory support allows the ventilator to generate pressure in proportion to the patient’s efforts. </li></ul><ul><li>With every breath, the ventilator synchronizes with the patient’s ventilatory efforts . (Giannouli, Webster, Roberts & Younes, 1999). </li></ul>
Nursing assessment in PAV mode:- <ul><li>Nursing assessment should include :- </li></ul><ul><li>Careful monitoring of the patient’s respiratory rate, </li></ul><ul><li>Arterial blood gases, </li></ul><ul><li>tidal volume, </li></ul><ul><li>minute ventilation, </li></ul><ul><li>Breathing pattern. </li></ul>
Continuous positive airway pressure (CPAP) mode <ul><li>The continuous positive airway pressure (CPAP) mode allows the patient to breathe spontaneously , while applying positive pressure throughout the respiratory cycle to keep the alveoli open and promote oxygenation . </li></ul><ul><li>Providing CPAP during spontaneous breathing also offers the advantage of an alarm system and may reduce patient anxiety if the patient has been taught that the machine is keeping track of breathing. </li></ul><ul><li>It also maintains lung volumes and improves the patient’s oxygenation status. </li></ul><ul><li>CPAP is often used in conjunction with PSV. </li></ul>
NURSES ROLE IN CPAP MANAGMENT <ul><li>Nurses should carefully assess for :- </li></ul><ul><li>tachypnea, </li></ul><ul><li>tachycardia, </li></ul><ul><li>reduced tidal volumes, </li></ul><ul><li>decreasing oxygen saturations, </li></ul><ul><li>increasing carbon dioxide levels. </li></ul>
Weaning trials using a T-piece <ul><li>Weaning trials using a T-piece or tracheostomy mask are normally conducted with the patient disconnected from the ventilator , receiving humidified oxygen only, and performing all work of breathing. </li></ul><ul><li>Patients who do not have to overcome the resistance of the ventilator may find this mode more comfortable,or they may become anxious as they breathe with no support from the ventilator. </li></ul>
NURSING ASSESSMENTS <ul><li>The Nurse monitors the patient closely and provides encouragement. </li></ul><ul><li>This method of weaning is usually used when the patient is awake and alert, is breathing without difficulty, has good gag and cough reflexes, and is hemodynamically stable. </li></ul><ul><li>During the weaning process, the patient is maintained on the same or a higher oxygen concentration than when on the ventilator. </li></ul>
NURSING ASSESSMENTS:- <ul><li>While on the T-piece, the patient should be observed for signs and symptoms of hypoxia, increasing respiratory muscle fatigue, or systemic fatigue. </li></ul><ul><li>These include restlessness ,increased respiratory rate greater than 35 breaths/min, </li></ul><ul><li>use of accessory muscles, tachycardia with premature ventricular contractions,and paradoxical chest movement (asynchronous breathing, chest contraction during inspiration and expansion during expiration). </li></ul><ul><li>Fatigue or exhaustion is initially manifested by an increased respiratory rate associated with a gradual reduction in tidal volume; later there is a slowing of the respiratory rate. </li></ul>
If the patient appears to be tolerating the T-piece trial, a second set of arterial blood gas measurements is drawn 20 minutes after the patient has been on spontaneous ventilation at a constant FiO2 pressure support ventilation. (Alveolar–arterial equilibration takes 15 to 20 minutes to occur.) Signs of exhaustion and hypoxia correlated with deterioration in the blood gas measurements indicate the need for ventilatory support. The patient is placed back on the ventilator each time signs of fatigue or deterioration develop. If clinically stable, the patient usually can be extubated within 2 or 3 hours of weaning and allowed spontaneous ventilation by means of a mask with humidified oxygen .
Successful weaning from the ventilator is supplemented by intensive pulmonary care. The following are continued: • Oxygen therapy • Arterial blood gas evaluation • Pulse oximetry • Bronchodilator therapy • Chest physiotherapy • Adequate nutrition, hydration, and humidification • Incentive spirometry Successful weaning from the ventilator is supplemented by intensive pulmonary care
Weaning From the Tube:- Weaning from the tube is considered when the patient can breathe spontaneously, maintain an adequate airway by effectively coughing up secretions, swallow, and move the jaw. If frequent suctioning is needed to clear secretions, tube weaning may be unsuccessful (Ecklund, 1999)
Weaning From Oxygen The patient who has been successfully weaned from the ventilator, cuff, and tube and has adequate respiratory function is then weaned from oxygen. The FiO2 is gradually reduced until thePaO2 is in the range of 70 to 100 mm Hg while the patient is breathing room air. If the PaO2 is less than 70 mm Hg on room air, supplemental oxygen is recommended. .
Nutrition <ul><li>Success in weaning the long-term ventilator-dependent patient requires early and aggressive but judicious nutritional support. </li></ul><ul><li>The respiratory muscles (diaphragm and especially intercostals) become weak or atrophied after just a few days of mechanical ventilation, especially if nutrition is inadequate. </li></ul><ul><li>Fat kilocalories produce less carbon dioxide than carbohydrate kilocalories. For this reason, a high-fat diet may assist patients with respiratory failure who are being weaned from mechanical ventilation. </li></ul><ul><li>A high-fat diet may provide as much as 50% of the total daily kilocalories. </li></ul>
Nutrition <ul><li>Adequate protein intake is important in increasing respiratory muscle strength. Protein intake should be approximately 25% of total daily kilocalories, or 1.2 to 1.5 g/kg/day. </li></ul><ul><li>a high-carbohydrate diet can lead to increased carbon dioxide production and retention, total carbohydrate intake should not exceed 25% of total daily kilocalories, or 2 g/kg/day in patientsbeing weaned from mechanical ventilation. </li></ul>
NUTRITION <ul><li>Care must be taken not to overfeed patients because excessive intake can raise the demand for oxygen and the production of carbon dioxide. </li></ul><ul><li>Total daily kilocalories should be closely monitored (Lutz &Prytulski, 2001). </li></ul>