Ventilators

1
Ventilators

• Kindred Hospital Louisville
• Education Module

2
Learning Objectives

• Identify the mechanics of breathing
• Identify indicators for mechanical ventilation
• Identify two types of ventilators
• Identify the Modes of Ventilation
• Discuss the Adjuncts to Mechanical Ventilation
• Identify the components of Ventilator Settings
• Describe the Nursing Care of the Mechanically
  Ventilated Patient
• Discuss Arterial Blood Gases

3
Components of Respiratory System

• Nasal Oral Cavities
• Nasopharynx
• Oropharynx
• Epiglottis
• Larynx
• Trachea
• Left Right Bronchus
• Left Right Lung
• Alveoli

4
Pathophysiology of Breathing

• During breathing, air is inhaled through the
  airway into millions of tiny sacs where gas
  exchange takes place (alveoli). Then the air
  mixes with the carbon dioxide-rich gas coming
  from the blood. This air is then exhaled back
  through the same airways to the atmosphere.
  Normally this pattern repeats itself from 12 - 20
  times a minute, but can increase or decrease to
  meet our bodys needs.
• The gas exchange that takes place as described
  above is the main function of the lungs. It is
  required to supply oxygen to the blood for
  distribution to the cells of the body, and to
  remove the carbon dioxide that the blood has
  collected from the cells of the body.

5
Pathophysiology of Breathing

• Gas exchange in the lungs occurs only in the
  smallest airways and the alveoli. It does not
  take place in the conducting airways (pathways)
  that carry the gas from the atmosphere. The
  volume of these conducting airways is called the
  anatomical dead space because it does not
  participate directly in the gas exchange.
• Gas is carried through the conducting airways
  through a process called convection.
• Gas is exchanged between the alveoli and the
  blood through diffusion.
• In normal, healthy lungs the drive to breathe
  comes from the need to regulate carbon dioxide
  levels in the blood, not from a desire to inhale
  oxygen.

6
Pathophysiology Contd

• One of the biggest factors that determines
  whether breathing is producing enough gas
  exchange to keep a person adequately oxygenated
  is the ventilation that each breath is
  producing.
• Ventilation is expressed as the volume of gas
  entering or leaving the lungs in a given amount
  of time. It can be calculated by multiplying the
  inhaled (or exhaled) volume of a gas (Tidal
  Volume) times the breathing rate.
• For example A person breathing in 0.5 Liters
  per respiration, who breathes 12 times a minute,
  has a volume of 6 Liters/minute

7
Pathophysiology Contd

• During normal breathing, the body selects a
  combination of tidal volume that is large enough
  to clear the dead space and add fresh gas to the
  alveoli, and a breathing rate that ensures the
  correct amount of ventilation is produced.
• There are two sets of forces that can cause the
  lungs and chest wall to expand the forces that
  are produced by the muscles of respiration when
  they contract and the force produced by the
  difference between the pressure at the airway
  opening and the pressure on the outer surface of
  the chest wall.
• In normal respiration, the muscular force is the
  only one that comes into play, when the
  respiratory muscles do the needed work to expand
  the chest wall, decreasing the pressure on the
  outside of the lungs so they expand, which draws
  air into the lungs.

8
Pathophysiology Contd.

• When respiratory muscles are not able to do the
  work required for ventilation, the pressure at
  the airway opening, and/or the pressure at the
  outer surface of the chest wall can be
  manipulated to produce breathing movements.
• When altering either of those pressures, you can
  do so in one of two ways. Either increase the
  pressure at the mouth and nose, so that air is
  forced into the lungs or lower the pressure on
  the chest wall external surface.

9
Breathing Pathophysiology

• Remember that an alteration in any of the areas
  associated with breathing/gas exchange can
  produce undesirable effects in your patients
  oxygenation.
• Within the chest wall, there is normally a
  constant negative pressure that facilitates
  respiration. If this negative pressure is
  disrupted, ventilation and oxygenation are
  disrupted.

10
Lung Anatomy
11
Indications for Mechanical Ventilation

• Acute dyspnea
• Significant respiratory acidosis
• Acute or impending ventilator failure (elevated
  PaCO2 gt50 mmHg with a pH lt 7.30)
• Severe oxygenation deficit despite high
  supplemental oxygen delivery (PaO2 lt 60 mmHg on
  FiO2 gt 60)
• Secretion/Airway Control
• Apnea, Respiratory Arrest

12
Common Diseases Requiring Mechanical Ventilation

• Acute Obstructive Disease acute severe asthma
  airway mucosal edema)
• Altered Ventilatory Drive hypothyroidism
  intracranial hemorrhage dyspnea-related anxiety
• Cardiopulmonary Problems CHF Pulmonary
  Hemorrhage
• Chronic Obstructive Pulmonary Disease emphysema,
  chronic bronchitis, asthma cystic fibrosis
  bronchiectasis
• Neuromuscular Disease ALS Guillian-Barre
  Cancer Malnutrition Infections
• Atelectatic Disease ARDS Pneumonia

13
Other Common Conditions Requiring Mechanical
Ventilation

• Burns and Smoke Inhalation inhalation injury,
  surface burns
• Chest Trauma Blunt injury flail chest
  Penetrating Injuries
• Fatigue/Atrophy Muscle overuse disuse
• Head/Spinal Cord Injury Meduallary brainstem
  injury Cheyne-Stokes breathing Neurogenic
  Pulmonary Edema
• Postoperative Conditions Cardiac Thoracic
  Surgeries
• Pharmacological Agents/Drug Overdose Muscle
  relaxants barbiturates Ca channel blockers
  long-term adrenocorticosteroids aminoglycoside
  antibiotics

14
Two Approaches to Mechanical Ventilation

• POSITIVE PRESSURE VENTILATION
• Uses the technique of applying positive pressure
  (relative to atmospheric pressure) to the airway
  opening

• NEGATIVE PRESSURE VENTILATION
• Uses the technique of applying negative pressure
  (relative to atmospheric pressure) to the
  external body surface

15
Positive Pressure Ventilators Simplified

• For safe operation of the ventilator, the
  following things are required
• Patient Interface The ventilator delivers gas
  to the patient through a set of flexible tubes
  called a patient circuit. This can have one or
  two tubes. The circuit typically connects the
  ventilator to the patient to either an
  endotracheal tube or tracheostomy tube.
• Power Sources Typically these are powered by
  electricity or compressed gas. The ventilator is
  usually connected to separate sources of
  compressed air and compressed oxygen. Because
  compressed gas has all the moisture removed, a
  humidifier is needed to moisten the gases being
  delivered to the patient.
• Control System This ensures the patient
  receives the desired breathing pattern. It
  involves setting the parameters of the size of
  the breath, how fast it is brought in out, and
  how much effort the patient must exert to signal
  the ventilator to start a breath.
• Monitors A pressure monitor, as well as volume
  and flow sensors to provide alarms if readings
  are outside the desired range.

16
Negative Pressure Ventilators Simplified

• For safe operation of the automatic ventilator,
  the following things are required
• Patient Interface The patient is placed inside
  a chamber with his or her head extending outside
  the chamber. The chamber may encase the entire
  body except the head(iron lung) or it may enclose
  just the rib cage and abdomen (cuirass
  pronounced cure-ahs). It is sealed to the body
  where the body where the body extends outside the
  chamber.
• Power Sources Electricity powered, to run a
  vacuum pump that periodically evacuates the
  chamber to produce the required negative
  pressure.
• Control System Sets breathing patterns.
• Monitors Alarms.

17
Modes of Mechanical Ventilation

• Controlled Mandatory Ventilation (CMV) The
  patient receives a set respiratory rate at set
  time intervals with a consistent tidal volume.
  This is generally only used with much sedation or
  paralytics, because patient efforts do not
  trigger the delivery of a breath by the machine.
  This is used when the patient must not expend
  energy to breathe.

18
Modes of Mechanical Ventilation

• Assist Control (AC) The patient receives a set
  respiratory rate at set time intervals with a
  consistent tidal volume, but when the patient
  initiates a breath on their own, the preset tidal
  volume is delivered. This decreases the
  patients effort of breathing, and ensures volume
  delivery.

19
Modes of Mechanical Ventilation

• Synchronized Intermittent Mandatory Ventilation
  (SIMV) The patient receives a preset
  respiratory rate at a set tidal volume, but the
  machine allows for the patient to breathe
  spontaneously during the machine breaths. If the
  patient breathes near the time that the machine
  is prepared to deliver the preset volume, the
  machine will deliver the preset tidal volume.
  The breaths that the patient initiates in between
  the machine breaths are not supplemented by the
  machine. It is usually tolerated well by the
  patient, because of the synchronicity involved.

20
Modes of Mechanical Ventilation

• Continuous Positive Airway Pressure (CPAP) Used
  either intermittently during long-term weaning as
  a way to strengthen the muscles, or as a final
  step before removing the patient from the
  ventilator, to see how they tolerate the lack of
  ventilatory assistance. All breaths are
  generated by the patient, and the patients
  effort determines the tidal volume. The machine
  simply provides a continuous airway pressure,
  supplemental oxygen, and apnea alarms. The
  continuous airway pressure makes the effort of
  breathing easier for the patient.

21
Modes of Ventilation

• Pressure Support (PS) When this mode is used,
  the patient initiates the breath, and the
  inspiration ends when a preset flow amount is
  delivered. The positive pressure is applied
  throughout inspiration and helps to increase the
  amount of tidal volume the patient pulls in and
  decreases the energy the patient has to use.

22
Adjuncts to Mechanical Ventilation

• Positive End Expiratory Pressure (PEEP)
• PEEP is the application of continuous airway
  pressure throughout expiration. The presence of
  this pressure in the airway prevents the complete
  collapse of the alveoli, and helps maintain that
  pressure until the next inspiration cycle begins.

23
Mode Review
24
Components of Ventilator Settings

• Rate
• Tidal Volume
• Percentage Oxygen
• Peep or Pressure Support

25
Rate

• The rate is the number of times the ventilator is
  set to provide a breath to the patient. This may
  vary from 8-20 breaths per minute.

26
Tidal Volume

• Tidal volume is the amount of gas the the
  ventilator is to provide to the patient with each
  breath. This volume will vary based on each
  patients height, weight, and gender. To
  calculate a very rough estimate of tidal volume,
  you can use 10 - 15cc per kilogram of body
  weight. So a 75lb. patient might have an ordered
  tidal volume of 750cc.

27
Percentage of Oxygen

• The percentage of oxygen supplied to the patient
  with every breath. This can be as low as 40 to
  as much as 100. Higher oxygen percentages for
  long periods of time increase the patients risk
  for oxygen toxicity and other pulmonary
  complications.

28
PEEP

• PEEP can be added to the regular ventilator
  settings, to provide the positive end expiratory
  pressure that helps to prevent the complete
  collapse of the alveoli.

29
Pressure Support

• The patient initiates the breath, and the
  inspiration ends when the preset flow target is
  delivered. The tidal volume will vary, depending
  on the patient. The positive pressure is applied
  throughout inspiration and helps the patient to
  pull in the tidal volume, and reduces their
  energy expenditure.

30
Nursing Care of the Mechanically Ventilated
Patient

• Nursing care of patients who are being
  mechanically ventilated requires some special
  considerations.
• Some special considerations relate specifically
  to the type of tube via which the patient is
  being ventilated (i.e. endotracheal or
  tracheostomy) and others related to the patient,
  and the ventilator itself.

31
Nursing Care of the Patient with an Tracheostomy
Tube

• Trach care should be performed at least every
  shift, and as needed as ordered by the patients
  Physician.
• The patient should always be pre-oxygenated with
  100 oxygen prior to suctioning.
• Saline should not be routinely instilled into the
  airway. Saline installation has been shown to
  increase infection rates and to cause decreased
  oxygen levels for longer periods of time than
  suctioning without it.

32
Nursing Care of the Mechanically Ventilated
Patient

• Pulmonary assessment is perhaps never as
  important as it is in the mechanically ventilated
  patient.
• These patients require frequent reassessments on
  a schedule and on an as needed basis.
• Further assessments can be documented in Protouch
  under Reassessments.

33
Nursing Assessment Components Breath Sounds

• Breath sounds should be assessed at least every
  four hours, and more frequently as needed.
• Both the anterior and the posterior chest need to
  be auscultated bilaterally.
• Clearly document any adventitious breath sounds
  that are heard, and report significant
  alterations to the Physician.

34
Nursing Assessment Components Rate Volume

• Make sure to assess and document the patients
  spontaneous respiratory rate and tidal volume.
  This information tells you a lot about the
  patients respiratory functioning.
• Note any changes in this area, and report
  significant findings to the patients Physician.

35
Nursing Assessment ComponentsPulse Oximetry

• Pulse oximetry is a useful monitoring tool, but
  provides minimal indication of the patients
  ventilatory or acid-base status.
• Readings can be affected by abnormal hemoglobins,
  vascular dyes, and poor perfusion.
• Plus, the machine cant distinguish between
  normal and abnormal hemoglobins, so a patient
  with carbon monoxide poisoning could have a pulse
  ox reading of 100.

36
Nursing Assessment ComponentsSputum

• A respiratory system assessment should include
  documentation of any sputum.
• Note the color tenacity odor frequency
  quantity of sputum for a thorough assessment.
• Note if the patient is able to expectorate
  his/her own sputum, or if suctioning is required
  to remove it.

37
Complications of Mechanical Ventilation

• One of the reasons for such a frequent and
  thorough assessment of the pulmonary system while
  patients are being mechanically ventilated is due
  to the many complications that can occur with the
  use of mechanical ventilation.
• Thorough assessments can lead to the early
  discovery of potential complications, heading off
  more serious complications later.

38
Complications of Mechanical Ventilation

• Positive Pressure Ventilation
• can cause hypotensiondecreased venous
  returndecreased cardiac output
• Other complicationspneumothoraxsubcutaneous
  emphysemaair emboluslocalized pulmonary
  hyperinflationnosocomial infectionsincreased
  intracranial pressure (cerebral edema)

39
ABG Overview

• Understanding ABGs are critical to understanding
  the respiratory status of the patient.
• As a nurse, it is essential you have a working
  knowledge of ABGs. That responsibility cannot
  be delegated to R.T.

• ABG Components
• pH
• PCO2
• HCO3
• Base Excess/Deficit
• PaO2

40
pH

• pH is the relative acidity or baseness of the
  blood.
• Normal human blood pH ranges from 7.35 - 7.45
• Less than 7.35 is considered acidotic and greater
  than 7.45 is considered alkalotic

41
pH

• Conditions that alter the pH of blood fall into
  one of four processes.
• One or more of these processes may be present in
  a patient with an abnormal acid-base status.

• Four Processes
• Metabolic Acidosis
• Metabolic Alkalosis
• Respiratory Acidosis
• Respiratory Alkalosis

42
Metabolic Processes

• Metabolic processes are those that primarily
  alter the bicarbonate concentration in the blood.
  A decrease in the blood concentration of
  bicarbonate leads to metabolic acidosis, while an
  increase in serum bicarbonate levels leads to
  metabolic alkalosis.

43
Respiratory Processes

• Respiratory processes alter the pH of the blood,
  by changing the carbon dioxide levels. Carbon
  dioxide that accumulates in the blood causes an
  acid state (carbonic acid).
• As respirations increase or decrease in rate, the
  level of carbon dioxide in the blood varies.
  Faster respirations cause decreased blood carbon
  dioxide levels, and slower respirations cause
  less carbon dioxide to be blown off, causing an
  increased serum carbon dioxide level.

44
Respiratory Processes

• Respiratory alkalosis occurs when respirations
  increase, leaving less carbon dioxide in the
  blood, and when respirations decrease, the carbon
  dioxide level in the blood increases, which can
  lead to respiratory acidosis.

45
PCO2

• PCO2 is the partial pressure of dissolved carbon
  dioxide in the blood.
• Most is excreted by the lungs, some is excreted
  in the kidneys as HCO3.
• Normal level is 35 - 45 mmHg.
• PCO2 level is a direct indicator of the
  effectiveness of ventilation
• As PCO2 rises, the blood becomes more acidic and
  the pH drops
• As PCO2 decreases the blood becomes more alkaline
  an pH rises
• If a change in the PCO2 level is the primary
  alteration, then a respiratory problem exists

46
HCO3

• Bicarbonate is the primary buffer in the body.
  Buffers neutralize acids.
• Normal range is 22 - 26 mmHg.
• As the HCO3 level rises, the blood becomes more
  alkaline and the pH increases.
• As the HCO3 level falls, the blood becomes more
  acidic and the pH decreases.
• If a change in HCO3 is the primary alteration,
  then a metabolic problem exists.

47
Base Excess/Deficit

• Measures the excess amount of acid or base
  present in blood. This is independent of changes
  in PCO2, so its a measure of metabolic acid-base
  balance.
• Increased HCO3 base excess (alkalosis)
• Decreased HCO3 base deficit (acidosis)

48
PO2

• The amount of oxygen dissolved in plasma
• Normal is 80 - 100 mmHg in healthy people
  breathing room air at sea level.
• Normal PO2 will decrease with altitude and aging.
• PO2 gt 60mmHg may be considered acceptable in
  critically ill, mechanically ventilated adults.
• Adequacy of PO2 must be weighed against the
  potential for oxygen toxicity

49
Analyzing Blood Gas Results

• Use the following simple four step process to
  interpret ABGs.
• Practice this until you are completely
  comfortable with it.
• Keep a cheat sheet with this information
  written down and refer to it!
• Practice, Practice, Practice!!!

50
Interpreting ABGs
51
Interpreting ABGs
52
Other Considerations

• Consider the patients overall health and disease
  processes.
• For every year past age 60, the normal value for
  pO2 drops by 1 mmHg.
• Oxygen the person is receiving.
• Hemoglobin level

• Chronic lung conditions
• Recent ventilator changes.
• Recent changes in patient status (i.e. codes,
  decannulation, etc. )

53
Case Study

• Mr. Hill has been on the ventilator for 24 hours.
  You volunteered to care for him today, since you
  know him from yesterday. The settings ordered by
  the pulmonologist after intubation were as
  follows A/C, rate 14, VT 700, FIO2 60. Since
  0700, Mr. Hill has been assisting the ventilator
  with a respiratory rate of 24 (Its now 1100).

54
Problem 1

• Describe Mr. Hills ventilator settings.

55
Problem 2

• You notice that Mr. Hills pulse oximetry has
  been consistently documented as 100 since
  intubation. You also notice that his respiratory
  rate is quite high and that hes fidgety, doesnt
  follow commands, and doesnt maintain eye contact
  when you talk to him. He hasnt had any sedation
  for 24 hours.

• Which lab test should you check to find out what
  his true ventilatory status is?

56
Problems 3 4

• 3
• Which two parameters on the ABG will give you a
  quick overview of Mr. Hills status?

• 4
• What are some possible causes of Mr. Hills
  increased respiratory rate?
• Give the nursing interventions you would do
  because of the possible causes too!

57
Case Study Continued

• Mr. Hill didnt have an ABG done this morning, so
  you get an order from the pulmonologist to get
  one now (1130). When it comes back, the PaCO2 is
  28, the pH is 7.48, and the PaO2 is 120 (normals
  PaCO2 35-45 mm Hg, pH 7.35-7.45 mm Hg, PaO2
  80-100 mm Hg).

58
Problem 5

• Based on the ABG, the pulmonologist changes the
  vent settings to SIMV, rate 10, PS 10, FIO2 40.
  The VT remains 700. Why? And, how will these new
  settings help Mr. Hill?

59
Wrap Up

• Always remember that without an intact,
  functioning respiratory system, you have no
  patient.
• BEWARE of the words Keep Previous under your
  nursing assessmentalways document what YOU
  heard, saw, smelt, felt, etc. Dont use Keep
  Previous!
• Turn in your answers to your nurse manager!