VENTILATOR VS THEIR INDICATION, TYPES, PARAMETER, COMPLICATIONS AND NURSING RESPONSIBILITY

 DEFINATION OF MECHANICAL VENTILATION

 Meaning of Mechanical Ventilation In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing.

INDICATIONS

  Protection of airway 

 Respiratory arrest or rate < 8/min

  Tachypnoea > 35/min 

 Inability to tolerate oxygen mask/CPAP/NIV, e.g. agitation,confusion  Removal of secretions 

 Hypoxaemia (Pa O2 < 8 kPa (< 60 mmHg); Sp O2 < 90%),despite CPAP with F iO2 > 0.6

 Hypercapnia if conscious level impaired or risk of raised intracranial pressure

  Worsening respiratory acidosis  Vital capacity falling below 1.2 L in patients with neuromuscular disease

  Removing the work of breathing in exhausted patients

 CLINICAL CONDITIONS

  Post-operative • e.g. After major abdominal or cardiac surgery

 Respiratory failure

  ARDS

  Acute severe asthma 

 Pneumonia 

 Aspiration

  COPD 

 Smoke inhalation, burns

  Circulatory failure 

 Low cardiac output: cardiogenic shock  Following cardiac arrest 

Pulmonary oedema

  Neurological disease 

Coma of any cause

  Status epilepticus 

 Drug overdose 

Respiratory muscle failure (e.g. Guillain– Barré syndrome, poliomyelitis, myasthenia gravis)

  Head injury: to avoid hypoxaemia and hypercapnia, and reduce intracranial pressure 

 Bulbar abnormalities causing risk of aspiration (e.g. cerebrovascular accident, myasthenia gravis

Types Of MECHANICAL Ventilation 

1.INVASIVE 

2. NON INVASIVE

Invasive ventilation 

• Mechanical ventilation via artificial airways which can either be endotracheal intubation or tracheostmy tube

Non invasive ventilation 

• It refers to the delivery of mechanical ventilation to the lungs using techniques that do not require an invasive artificial airway(ETT, TT) 

• It provide breathing support through CPAP,BiPAP.

Classification of positive-pressure ventilators 

• Ventilators are classified according to how the inspiratory phase ends. The factor which terminates the inspiratory cycle reflects the machine type.

 • They are classified as: 

 Volume cycled ventilators 

 Pressure cycled ventilators 

 Time cycled ventilators17. 

1- Volume-cycled ventilator

 • The ventilator delivers a preset tidal volume (VT), and inspiration stops when the preset tidal volume is achieved.

 • Most commonly used in adult.

 2- Pressure-cycled ventilator

 • In which inspiration is terminated when a specific airway pressure has been reached.

 3- Time-cycled ventilator

 • In which inspiration is terminated when a preset inspiratory time, has elapsed. 

• Time cycled machines are not used in adult critical care settings. They are used in pediatric intensive care areas.

Ventilator mode 

The way the machine will ventilate the patient in relation to the patient’s own respiratory efforts

Various modes of mechanical ventilators

  Controlled mandatory ventilation (CMV) 

 Assist/control (AC)

  Intermittent mandatory ventilation (IMV) 

 Synchronized intermittent mandatory ventilation (SIMV)

  Positive end-expiratory pressure (PEEP)

  Continuous positive airway pressure (CPAP) 

 Bilevel positive airway pressure (BiPAP)

  Pressure support ventilation (PSV) 

 Volume ventilation plus (VV1) 

 Pressure-controlled ventilation (PCV)

  Airway pressure release ventilation (APRV) 

 Inverse ratio ventilation (IRV)

  High-frequency oscillatory Ventilation (HFOV)

  Proportional assist ventilation (PAV) 

 Pressure-regulated volume control (PRVC)

Settings of Mechanical Ventilation

 • Mechanical Ventilator Settings regulates the rate, depth and other characteristics of ventilation.

 Settings are based on the patient’s status (ABGs, Body weight, level of consciousness and muscle strength)

PARAMETERS OF MECHANICAL VENTILATION ARE

  Respiratory Rate (f) :-Normally 10-20b/m

  Tidal Volume (VT) :-5-15ml/kg

  Oxygen Concentration(FIO2):-b/w 21-90% 

I:E Ratio:-1:2 

Flow Rate:-40-100L/min Sensitivity/Trigger:- 0.5-1.5 cm H2O Pressure Limit:-10-25cm H2O

  PEEP :- Usually, 5-10 cmH2O12. 

TERMINOLOGY OF VENTILATION PARAMETERS 

A. Lung Volumes 

1. Basic volumes: 

a. Tidal Volume (VT, TV): 

volume of gas exchanged each breath; can change as ventilation pattern changes .(500 ml) 

b. Inspiratory Reserve Volume (IRV): maximum volume that can be inspired, starting from the end inspiratory position (potential volume increase at the end of inspiration).(3000ml) 

c. Expiratory Reserve Volume (ERV): maximum volume that can be expired, starting from the end expiratory position (potential volume decrease at the end of expiration)(1200ml) 

d. Residual Volume (RV): 

volume remaining in the lungs and airways following a maximum expiratory effort (1300 ml)19. 

2. Capacities:combined volumes 

a. Vital Capacity (VC): 

maximum volume of gas that can be exchanged in a single breath VC = TV + IRV + ERV (4700 ml) 

b. Total Lung Capacity (TLC): maximum volume of gas that the lungs(and airways) can contain TLC = VC + RV = TV + IRV + ERV + RV (6000 ml) 

c. Functional Residual Capacity (FRC): volume of gas remaining in the lungs (and airways) at the end expiratory position FRC = RV + ERV (2500 ml) d. Inspiratory capacity (IC): maximum volume of gas that can be inspired from the end expiratory position . IC = TV + IRV (3500 ml)20. 

OTHER TERMINOLOGY 

a. Peak velocity 

(e.g. peak expired flow rate) normal value 400-600 liters/minute 

b. Timed vital capacity: 

volume of gas that can be expired from the lungs with maximum effort in a given time . 1) Usually expressed as a fraction of the total volume expired in a maximum effort, the Forced Vital Capacity (FVC) 2) Normal value of FEV1 / FVC ≥ 80%

c. Fraction of inspired oxygen (FiO2) The concentration of O in the inspired gas, usually between 0.21 (room air) and 1.0 (100% O )17. 

• Tidal volume (VT) - 

The amount of air delivered to the patient per breath. It is customarily expressed in milliliters. • A starting point for the VT setting is 8 to 10ml/kg of ideal weight18.

 • Respiratory rate/frequency (f)

  The number of breaths per minute. This can be from the ventilator, the patient, or both.

 The RR is set as near to physiological rates (14 to 20 breaths/min) as possible.19. 

• Minute ventilation (V E) 

The product of V and respiratory frequency (VT• f). It is usually expressed in liters/minute.20. 

• Exhaled Tidal Volume 

It is the amount of gas that comes out of the patients lungs on exhalation.

 This is the most accurate measure of the volume received by the patient  If the EVT deviates from the set VT by 50ml or more, troubleshoot the system to identify the source of gas loss.21.

 • Inspiratory to Expiratory ratio 

The I:E ratio is usually set to mimic the pattern of spontaneous ventilation. Generally the I:E ratio is set at 1:2, that is 33% of the respiratory cycle is spent in inspiration and 66% in the expiratory phase.

• Inverse Inspiratory to Expiratory ratio 

I:E ratios such as 1:1,2:1 and 3:1 are called inverse I:E ratios

 Inverse I:E ratio allows unstable alveoli time to fill and also prevents collapse by shortened expiratory phase.

• Positive end-expiratory pressure (PEEP) 

 The amount of positive pressure that is maintained at end-expiration. 

Typical settings for PEEP are 5 to 20 cm H2O 

 PEEP increases oxygenation by preventing collapse of small airways It increases the functional residual capacity of the lungs

• SIGH - A sigh is a mechanically set breath with greater volume than the preset VT, usually 1.5 to 2 times the VT28. 

• Peak airway pressure (Paw): The pressure that is required to deliver the VT to the patient. It has a unit of centimeters of water (cm H2O).

 • Plateau pressure (Pplat): The pressure that is needed to distend the lung. This pressure can only be obtained by applying an endinspiratory pause. It also has a unit of cm H2O30. 

• Peak inspiratory flow: The highest flow that is used to deliver VT to the patient during inspiratory phase. It is usually measured in liters/minute. Usual setting 40-80L/min

• Mean airway pressure: The time-weighted average pressure during the respiratory cycle. It is expressed in cm H2O

Connection to Ventilators

 • Face Mask 

• Airway

• Laryngeal Mask

 • Tracheal Intubation

 • Tracheostomy

Complications of Mechanical 

Ventilation

 I- Airway Complications 

II- Mechanical complications 

III- Physiological Complications

 IV- Artificial Airway Complications

Airway Complication 

1- Aspiration 

2- Decreased clearance of secretions

 3- Nosocomial or ventilator-acquired pneumonia 

Mechanical complications 

1- Hypoventilation 

2- Hyperventilation 

3- Barotrauma 

4- Alarm “turned off” 

5- Failure of alarms or ventilator

 6- Inadequate nebulization or humidification 

7- Overheated inspired air, resulting in hyperthermia

Physiological Complications 

1- Fluid overload with humidified air and sodium chloride (NaCl) retention 

2- Depressed cardiac function and hypotension 

3- Stress ulcers 

4- Paralytic ileus 

5- Gastric distension 

6- Starvation Artificial Airway Complications 

• Complications related to Endotracheal Tube 

• Complications related to Tracheostmy Tube

PATIENT CARE VS VENTILATOR 

Nursing Management How to keep the Ventilator ready to receive the case ? 

*Check the Air and oxygen connections Connect the Ventilator tubes to ventilator

*Connect the chest lung to the ventilator tubing's Make sure that you correctly connected the tubing's and check for any looseness

* Connect the servo guard (From the patient) Connect the filter (To the Patient)

*Check the tubing’s for any leakage » Change the Bacteria filter

*Change the bacteria filter

 Patient Goals VS ventilator :

 • Patient will have effective breathing pattern. 

• Patient will have adequate gas exchange. 

• Patient’s nutritional status will be maintained to meet body needs. 

• Patient will not develop a pulmonary infection. 

• Patient will not develop problems related to immobility.

 • Patient and/or family will indicate understanding of the purpose for mechanical ventilation

• Observe changes in respiratory rate and depth; observe for the use of accessory muscles.

 • Observe for tube misplacement- note and post cm. Marking at lip/teeth after x-ray confirmation

 • Prevent accidental extubation by taping tube securely, checking q.2h.; restraining/sedating as advised 

• Inspect thorax for symmetry of movement. Determines adequacy of breathing pattern; asymmetry may indicate hemothorax or pneumothorax. . Measure tidal volume and vital capacity. • Asses for pain 

• Monitor chest x-rays • Maintain ventilator settings as ordered.

• Elevate head of bed 60-90 degrees. This position moves the abdominal contents away from the diaphragm, which facilitates its contraction. 

• Monitor ABG’s. Determines acid-base balance and need for oxygen. 

• Observe skin color and capillary refill. Determine adequacy of blood flow needed to carry oxygen to tissues

 • Observe for tube obstruction; suction; ensure adequate humidification.

 • Provide nutrition as ordered, e.g. TPN, lipids or parental feedings. 

• Use disposable saline irrigation units to rinse in-line suction; ensure ventilator tubing changed q. 7 days, in-line suction changed q. 24 h.; ambu bags changes between patients and whenever become soiled.

 • Assess for GI problems. Preventative measures include relieving anxiety, antacids or H2 receptor antagonist therapy, adequate sleep cycles, adequate communication system. 

• Maintain muscle strength with active/active-assistive/passive ROM and prevent contractures with use of span-aids or splints

 • Explain purpose/mode/and all treatments; encourage patient to relax and breath with the ventilator; explain alarms; teach importance of deep breathing; provide alternate method of communication; keep call bell within reach; keep informed of results of studies/progress; demonstrate confidence

Which we should not forget 

• Suctioning

 •  Mouth care 

•Nebulization

Plan of care for Ventilated Patients 

To provide effective breathing pattern to the patient. 

To ensure adequate gas exchange. Maintain nutritional status to achieve body needs of the patient. 

To prevent pulmonary, circulatory or bed- rest complications.

 Patient and/or family will indicate the understanding of the purpose for mechanical ventilation.

EARLY MOBILIZATION 

It can also be performed in sedated or unconscious patients. Protocols include- semirecumbent positioning with the head positioned at 45degrees, frequent changes in postures, daily sessions of joint passive movement, and passive bed cycling and electrical stimulation

MANAGEMENT OF AIRWAY SECRETIONS 

Immobilised patients may suffer from atelectasis, impaired cough mechanism, inability to expel secretions, weakness to expiratory muscles, etc. So, helping airway clearance in these patients is necessary. 

POSTURAL DRAINAGE:

 It includes gravity- assisted positions, deep breathing exercise, chest clapping, shaking or vibration, and incentivized cough to move secretions toward the upper airways.

PROPER POSITIONING

INSUFFLATION-EXUFFLATION 

Cough assists such as a mechanical insufflator/exsufflator clears secretions by gradually applying a positive pressure to the airway then rapidly shifts to negative pressure, producing a high expiratory flow. By contrast, direct tracheal suction applies negative pressure to a small, localized area.

ROTATIONAL THERAPY

 Continuous rotational therapy uses special beds to turn patients along the longitudinal axis up to 60degrees on each side, with preset degree and speed of rotation. It can reduce the risk of sequential airway closure and pulmonary atelectasis, resulting in reduction of the incidence rate of lower respiratory tract infection and pneumonia, and the duration of endotracheal intubation and length of hospital stay.