Mechanical

1
Mechanical
Ventilation
Kitty Chan School of Nursing,The Hong Kong
Polytechnic University Email hskittyc_at_inet.polyu.
edu.hk Date 2005
2
Objectives

• Upon completion of the module, the students
  should be able to
• Have a basic understanding of the mechanics and
  physiology of respiration
• develop a fundamental concept of noninvasive and
  invasive mechanical ventilation
• appreciate the clinical significance of various
  modes of ventilatory support
• understand the basics of providing nursing care
  to clients with mechanical ventilation.

3
Indicative Readings
Wiegand, L-M D. J. Carlson, K. K. (Eds.)
(2005). American Association of Critical-Care
Nurses AACN Procedure Manual for Critical Care.
(5th ed.). Philadelphia W B Saunders. Section 4
4
Introduction

• Gaseous exchanges may be improved by using
  mechanical ventilation, thereby relieving acute
  respiratory distress and reversing hypoxemia or
  acidosis.
• Furthermore, the oxygen consumption may be
  minimized the sedatives administration is
  allowed in case of a flail chest or increased
  intracranial pressure. This is achieved by
  manipulating the following elements
• Alveolar Ventilation
• Lung Volume
• End Expiration
• Functional Residual Capacity
• Reduced Work of Breathing

5
In this module, we will explore the above
physiological parameters as well as their effect
on the cardiopulmonary system. Since various
modes are available with different or the latest
models of ventilators, the emphasis is placed on
the principles of the basic ventilation
strategies. Familiarize yourself with the
conventional ventilation modes and the related
nursing care. If you are interested, you are
highly encouraged to further study the latest
ventilation modes and their application are
highly encouraged. Cardiopulmonary assessments
and arterial blood gas are the key to evaluating
the patients clinical outcome. Hence, the module
on Oxygenation Monitoring closely related to this
one. It is imperative to relate the materials in
these 2 modules with the clinical scenarios that
you encounter.
6
Mechanics of Respiration 1

• 1. Pulmonary Airway Resistance (R)
• This is the pressure difference between the
  atmospheric pressure at the mouth and the
  alveolar pressure
• ( flow of gas per time limit)

• Inspiration Bronchioles stretched ? flow
  resistance ?
• Expiration Bronchioles recoil
• ? airways become narrow
• flow resistance ?

7
Mechanics of Respiration 2

• Factors causing ? Airway Resistance
• Bronchospasm
• ? secretions
• Foreign bodies
• Tumour or stenosis
• Oedema
• Emphysema

8
Mechanics of Respiration 3

• 2. Compliance (C)
• This is the Elasticity Expansibility of the
  lungs
• (inversely proportional to elastic recoil)

Low Compliance
High Compliance
? Overdistension ? Volutrauma (Barotrauma) -
structural damage to alveoli - capillary
compression ? ? perfusion
9
Mechanics of Respiration 4

• Factors causing ? in Compliance
• Adult Respiratory Distress Syndrome (ARDS)
• Pulmonary oedema
• Atelectasis
• Fibrosis
• Pneumothorax
• Aspiration

? Compliance e.g. in emphysema ? loss of lung
parenchyma ? ? recoil / lung elasticity ? ?
transpleural pressure ? small airways collapse ?
? expiratory flow ? ? work of breathing (WOB) to
produce adequate inspiratory flow
10
Mechanics of Respiration 5

• 2. Compliance (contd)
• Static Compliance (CST)
• Measurement of Lung Tissue Compliance ( small
  airways alveoli Elastic)
• No Gas Flow into or out of the lungs
• CST Exhale Tidal Volume/Plateau pressure - PEEP
• Normal 70-100ml/cmH20

11
Mechanics of Respiration 6

• 2. Compliance (contd)
• Dynamic Compliance (CDYN)
• Measurement of Lung Tissue Compliance AND
  Resistance to Gas Flow (Chest wall Airways
  Non-Elastic)
• CDYN Exhale Tidal Volume/Peak Inspiratory
  Pressure - PEEP
• Normal 50-80ml/cmH20

• Airway Resistance The ONLY abnormality (e.g.
  bronchospasm)
• ? CDYN change independently
• No corresponding CST ?
• Always compare trends of CDYN ? or CST ?
  independently

12
Mechanics of Respiration 7

• 3. Work of Breathing (WOB)
• WOB Pressure x Area x Distance
• Pressure x Volume
• ? WOB

• Restrictive Ventilation
• ? Compliance e.g., pulmonary oedema
• ? ? elastic work
• (flow resistance unchanged)

• Obstructive Ventilation
• Narrow airways e.g., COPD
• ? ? flow resistance (Friction work)

13
Physiology of Gaseous Exchange

• Adequacy of pulmonary gaseous exchange depends
  on
• 1. Alveolar Ventilation (V) 4L/min
• 2. Diffusion
• The alveolar-capillary membrane make up the
  diffusion surface of the lungs for gaseous
  exchange
• Amount of O2 diffusion reduced if this surface
• ? size
• ? thickness
• 3. Perfusion (Q) at the alveolar capillary level
• Cardiac Output (CO) 5L/min

?
e.g., destroyed alveolar-capillary interface in
emphysema
?
?Regional differences exist in ventilation
perfusion
14
Gravity-Dependent Nature of Pulmonary Blood Flow
Vertical Gradient of Lung Zones ERECT/
UPBRIGHT Most Dependent Lung Region at the bases
of the lung ?

• Greatest Blood Flow
• SUPINE posterior lung zones
• LATERAL dependent side

15
Matching of Ventilation Perfusion
Overall V/Q ratio 4/5 0.8
16
V/Q Mismatch Dead Space

• Ventilation in EXCESS of Perfusion V gt Q
• Alveolar Ventilation (Vt - Vd)
• Functional/Physiological Dead Space (Vd)
• NO sufficient gas exchange Vd 2ml/KgBW
• (total 20-200ml in adults)
• Anatomical Dead Space nasopharynx, trachea,
  large conduct airways ? NO Ventilation to
  perfused areas
• Alveolar Dead Space 20-30 of total ventilation
  (Vt) Ventilation without/insufficient perfusion
• Vd /Vt ? gt 0.5 ? Hypoxemia / Hypercarbia

17
Anatomical Dead Space
? NO VENTILATION TO PERFUSED AREAS 2 of
cardiac output flow in areas without alveolar
ventilation units e.g., bronchial veins
pleural veins
18
Alveolar Dead Space

• Anatomical Dead Space remains unchanged
• ? Alveolar Dead Space
• ? Functional/Physiological Dead space

VENTILATION WITHOUT PERFUSION

• ? RR ? ? minute volume (Vt x f )
• ? ? alveolar ventilation (Vt - Vd) x f
• WOB ? with escalating dead space ventilation gt
  0.7- 0.8 ? Spontaneous breathing failure to
  exhale ? CO2

19
V/Q Mismatch Shunting

• Shunting V/Q lt 1.0
• Perfusion WITHOUT ventilation (?V), or Perfusion
  in EXCESS of Ventilation (?Q)
• Blood from or through non-ventilated areas
• Normal Shunt
• Perfusion of Right Lung Zone Left Lung Zone
• Shunting equals bilaterally (20-30 VT)
• True Shunt ? Anatomical Shunt
• Total Absence of Gaseous Exchange in the
  Alveolar-Capillary Unit (V/Q 0)

20
V/Q Mismatch Shunting

• True (Absolute) Shunt Intrapulmonary
  Right-to-Left Shunt
• Significance

Shunting gt 30 O2 Output exerts little change
in arterial oxygenation with ? FIO2 ? ? FIO2 to
minimal required level if there is no improvement
in PaO2 ? ? Risk of oxygen toxicity
21
True Shunt 1
NO VENTILATION
Blood flows through the lungs WITHOUT Significant
Gaseous Exchange pathology includes
atelectasis, bronchospasm (similar to blood
bypassing the pulmonary circuit from the right to
left ventricle)
22
Hypoventilation
?
? HYPOVENTILATION TO PERFUSED AREAS generalized ?
gas flow ? ? total ventilation ? impaired
gaseous exchange VltQ ? V/Q lt 1
Pulmonary Vein suboptimal oxygenation
23
True Shunt 2
Perfusion WITHOUT Significant Gaseous Exchange in
the fluid-filled alveolar-capillary unit e.g.,
consolidative-infiltrative diseases, pulmomary
oedema
24
Hypoxic Pulmonary Vasoconstriction

• Intrinsic Mechanisms in maintaining V/Q Balance
• Reflex narrowing of vascular systems where blood
  automatically shunts from a poorly ventilated
  region to an adequately ventilated zone
• Inhibiting factors to the self-regulation of V/Q
  
• O2 THERAPY ? ? Blood flow to poorly ventilated
  regions
• Vasodilators
• Hypocapnia ? Alkalosis ? Vasodilatation
• Pneumococcal Infection

25
Regional Hypoxic Vasoconstriction
NO VENTILATION
Vasoconstriction ?
The V/Q ratio is balanced through regional
hypoxic vasoconstriction ? Hemoglobin
Oxygenation is maximized If this mechanism fails
? a right-to-left shunt occurs
26
Strategies to Minimize V/Q Inequlities

• Treat Underlying Causes
• Alveolar Pulmonary Capillary Pressures
  Adjustment
• Medications
• Mechanical Ventilation
• Body Positioning Gravity-dependent nature of
  perfusion
• ?Would you turn a patient laterally with good
  lung down or bad lung down to optimize the
  gaseous exchange? How about to prone position?

27
Acute Respiratory Distress or Failure

• Hypoxemic Respiratory Failure (Failure to
  Oxygenate)
• Hypoventilation
• Pulmonary Disorders
• Oxygen Delivery Uptake Imbalance (DO2/VO2
  Imbalance)
• Hypercapnic Respiratory Failure (Failure to
  Ventilate)
• Exhaustion of Respiratory Muscles
• Gas trapping Hyperinflation due to Airway
  Obstruction
• Impaired CNS Respiratory Drive
• Loss of Hypoxic Drive

28
Common Intrapulmonary Causes of Respiratory
Failure
29
Clinical Presentation of Respiratory Failure
Early Indicators Dyspnoea Restlessness ?BP Tachycardia Dysrhythmias Cool Dry Skin Anxiety Headache Fatigue
Intermediate Indicators Tachypnoea Hypotension (? Vasodilation) Dysrhythmias Confusion Lethargy
Late Indicators Cyanosis Diaphoresis Coma Respiratory Arrest
30
Cardinal Signs Symptoms of Respiratory Failure

• PaO2 lt 6.7KPa/60mmHg (spontaneous breaths in
  room air)
• PaO2 lt 8.0KPa (FiO2 gt 0.5)
• PCO2 gt 7.3KPa/50mmHg (increasing trend)
• Tachypnoea gt 35 -45/minute Laboured or
  Irregular Pattern
• VT 3- 5mL/KgBW or Vital Capacity lt 15mL/Kg

31
Mechanical Ventilation

• Non-invasive Positive Pressure Ventilation
  (NIPPV)
• Negative Pressure Ventilator
• CPAP Circuit
• BiPAP
• Invasive Mechanical Ventilation
• Positive Pressure Ventilator (Conventional IPPV)
• High-Frequency Ventilator
• Liquid Ventilator

32
Appropriate Ventilation Support
associated with Vital Capacity
Mishoe S C Welch M A Jr 2002 Critical Thinking
in Respiratory Care A Problem-Based Learning
Approach. New York McGraw Hill.
33
Non-Invasive Positive Pressure Ventilation BiPAP
This is a comedy to stimulate your ideas. Please
focus on the application of the helmet and the
mask of the BiPAP discuss the scenario according
to the next slide.
Courtesy from Chan K M, Chan S M, Chan S W V,
Lee K M, Ngan S F, Yip N S, Yeung S K, Lai L T
2003 BiPAP Theory and ABG Interpretation. Drama
in Unpublished Student Project School of
Nursing, The Hong Kong Polytechnic University.
34
Specific Nursing Care to Clients on BiPAP

• With regard to the drama, explore the relevant
  nursing care for clients on BiPAP in relation to
  the following
• Appropriate choice of mask
• Application of BiPAP machine
• Client assessment and safe nursing care
• Ventilator assessment
• Potential complications related interventions
• Ongoing psychological support communication

35
Various Types of BiPAP Masks
Photos used with permission from Kwong, D., Nurse
Specialist ICU PMH (2005)
36
Full Face Mask
Photos used with permission from Kwong, D.,
Nurse Specialist ICU PMH (2005)
37
Full Face Mask
Plateau valve
Sizing guage
Photos used with permission from Kwong, D., Nurse
Specialist ICU PMH (2005)
38
? Please note that bacterial filter has to be
connect connected between the mask and the
exhaust valve
39
BiPAP Candidates

• Alert cooperative
• No upper airway obstruction
• No facial trauma, surgery nor burn
• No excessive pulmonary secretions/ vomiting
• Airway protection by intubation not required
• Haemodynamically stable
• Properly fitted mask

40
Noninvasive Positive Pressure Ventilation 1

• Indications
• Decrease in Work of Breathing
• Regular or Continuous Management for Ventilatory
  Dependent Clients
• Acute or Emergency Ventilatory Support where when
  intubation is inappropriate
• Hypoxemic Respiratory Failure
• Hyppercarbia e.g., in Exacerbations of COAD
• Weaning from Mechanical Ventilation
• Sleep Apnoea

41
Noninvasive Positive Pressure Ventilation 2

• Candidates with Undesirable Outcome
• Severe acidosis
• Poor pre-morbid state
• Presence of complications
• Little or No improvement in respiratory distress
  or acidosis within the initial trial of NIPPV
• Uncooperative
• Relatively contraindicated in infectious
  diseases e.g., in SARS

42
BiPAP Advantages

• Intubation Not Required
• Improves the Efficacy of Spontaneous Respiration
• Permits Optimal Synchrony with Assisted Breathing
  Patient Effort
• Matches Patient Volume Duration of Inspiration
• Reduce Time Lag Between Patient Inspiration Gas
  Flow Delivery, Hence, Decreases WOB
• Promotes Comfort Better Tolerance
• Minimizes Complications

43
BiPAP Modes

• Spontaneous Mode
• Flow-Triggered Inspirations (40mL/sec)
• IPAP initiated until inspiratory flow the leak
  flow (or 180msec)
• Spontaneous/Timed (S/T) Mode Controlled Breaths
  Synchronized with Time-triggered Inspirations
• Timed Mode (T) IPAP Time determines the
  Breaths per Minute

44
BiPAP Modes

• BiPAP PS CPAP
• Pressure Support (PS) IPAP
• CPAP EPAP

Expiration ?
? Inspiration
CPAP Spontaneous Respiration
45
BiPAP IPAP EPAP Waveform

• BiPAP IPAP EPAP

BiPAP Spontaneous Respiration
46
Clinical Parameters Monitoring 1

• Ventilator Settings
• Mask Adjustment
• Air Leak (patient leak circuit leak)
• Choice of mask exhalation port
• Skin Necrosis
• Gas Exchange Responses
• Patients Subjective Responses
• Mental Status
• Comfort
• Dyspnoea

47
Clinical Parameters Monitoring 2

• Gas Exchange Responses
• Objective Data
• SpO2 ABG
• Rate Pattern of Respiration ( Trigger)
• Respiratory Distress
• Chest Expansion
• Secretions
• Heart Rate
• CXR
• Abdominal Distension

48
Invasive Mechanical Ventilation
49
Indications for Mechanical Ventilation

• Acute Respiratory Distress or Failure
• Stabilization of Chest Wall e.g., Flail Chest
• Prevention of Atelectasis
• ? ICP Maintaining Constant CPP

50
Mechanism of Cycling in Positive Pressure
Ventilator
? Inspiration ends when the preset controlled
variable is attained
51
Conventional Ventilatory Modes
52
Pressure-Time Waveform
Inflation Hold
Alveoli Inflation
53
Pressure-Time Waveforms

• Peak Inspiratory Pressure (PIP) depends on
• Resistance
• Compliance
• Inspiratory flow
• Tidal volume

54
Mandatory Breaths Flow-Time Waveform
55
Pressure Control Flow-Time Waveform
56
Volume-Time Waveform
57
Ventilation Modes CMV

• Indications for absolute control
• No or minimal respiratory effort
• Sedation neuromuscular blockage to suppress
  respiration
• Intrinsic Respiration ? Impaired gaseous
  exchange or oxygenation e.g., in flail chest
• Patients comfort WOB compromised
• When triggering effort occurs, ventilator alarms
  (usually a high pressure alarm signifying an ?
  in airway pressure or resistance) inspiration
  will be terminated.
• This is called fighting of the ventilator
• Interventions such as sedation or switching to
  other ventilation modes may be necessary as
  appropriate

58
CMV Waveform Basic Features

• Preset
• Breath Frequency (RR/minute)
• Tidal Volume
• Time Intervals of Machine Breaths
• Spontaneous breath triggered machine breaths
  are NOT ALLOWED

? Asynchronization or Fighting of the
Ventilator occurs if spontaneous breaths emerge.
This drastically impairs the gaseous exchange
since inspiration will be aborted by the machine
once the peak airway pressure reaches the set
high pressure limit (usually 50L/min). The
underlying cause must be identified and the
interventions must be appropriate.
59
ACMV Waveform Basic Features

• Patient may Trigger Additional Breaths
• Spontaneous Breaths with Preset Tidal Volume
• Minute Volume varies
• Minimal preset rate volume guaranteed
• ? WOB inspiratory demand met
• Sense of comfort promoted
• Close monitoring of sensitivity, flow rate
  acid-base status

60
SIMV Basic Features

• Preset (Same as ACMV)
• Breath Frequency (RR/minute)
• Tidal Volume
• Time Intervals of Machine Breaths
• Spontaneous breath ALLOWED Spontaneous VT
  Varies
• Total RR Preset RR Spontaneous RR
• Total MV Preset RR x VT (preset) Spontaneous
  MV

61
SIMV Waveform Basic Features

• Assisted Breaths Synchronized Spontaneous
  Breaths that fall on Mandatory Machine Breaths
• TVassist TVpreset
• TVassist usually gt TVspont

• Back up Apnoea Parameter between Preset RR
  Interval

62
Ventilation Modes PS

• Description
• AUGMENT Spontaneous Respiration with preset
  amount of inspiratory positive pressure
• PS can be used-
• independently
• in conjunction with SIMV
• ? PS inactive in mandatory breaths
• Onset triggered by patient
• Flow-cycled, pressure-limited ventilation
• VT RR are determined by the patient

63
Pressure Support (PS) Waveform Basic Features
64
SIMV PS
Mandatory Breath ?
Pressure Supported Breaths ? ?
Assisted Breaths Mandatory Spontaneous Breaths
Synchronized TV as preset PS Inactivated
PS Activated TV in Spontaneous Breaths Augmented
? TVAugmented gt TVSpont
65
Ventilation Modes CPAP

• Description
• Constant gas flow at a preset pressure
• Demand valve circuit-
• considerable trigger effort is required to open
  the demand valve ? ? WOB
• Continuous flow circuit-
• Flow-triggering provides a continuous flow of
  gas
• Time lag reduced ? ? WOB
• Use in combination with Pressure Support
  further ? WOB

• Differentiates between CPAP PEEP
• CPAP is an independent ventilation
  mode/non-invasive ventilation circuit
• PEEP is used in conjunction with other
  ventilation modes

66
PEEP Adjunct Features

• Improves Oxygenation
• Prevents the collapse of small airways
  atelectasis
• Prevents repeated small airways from opening and
  closing
• ? ? lung injury
• ? Functional Residual Capacity ? Better V/Q
  Matching
• ? WOB

• ? Caution
• PEEP ? intrathroracic pressures (impedes
  lymphatic drainage) ? Pulmonary Oedema
• There is NO reduction in post-cardiac surgery
  mediastinal bleeding (transmural pressure is
  transmitted across the walls of the blood vessel
  but is not reduced)

67
Lung Volumes PEEP
68
ACMV PEEP
? Original baseline WITHOUT PEEP is at zero

• When PEEP is implemented, the baseline at the
  end of theexpiration (i.e., the beginning of
  next inspiration) is raised to the set PEEP level.

For instance PEEP 5cmH2O
Negative
inspiratory pressure if remain unchanged
2cmH2O, the level during the trigger actually
drops by 2cmH2O below the PEEP, i.e. to 3cmH20
( NOT TO -2cmH2O) The sensitivity that is set at
2cmH2O will automatically adjust itself deliver
synchronized breaths once the inspiratory force
attains the designated set pressure
69
Pressure Support (PS) PEEP
70
Effect of PEEP Application on the Alveoli
PEEP Pulmonary Perfusion will be further
compromised
Pierce L N B 1995 Guide to Mechanical Ventilation
and Intensive Respiratory Care. Philadelphia W B
Saunders.
71
Optimal PEEP

• Goal Least amount of PEEP titrate according to
  ABG
• SaO2 ? 92
• PaO2 ? 60mmHg
• FiO2 lt 0.6

• ? Caution
• Cardiac Output or Venous Return Compromised
• Haemodynamic Instability
• Auto-PEEP
• Taper PEEP to complete withdrawal to avoid the
  sudden collapse of small airways ? Hypoxemia
• An in-line suction catheter should be used to
  prevent the ventilator circuit from disconnecting
• The PEEP valve should be used in a manual
  bag-valve mask in a portable ventilator

72
Auto-PEEP/ Intrinsic PEEP

• Definition Spontaneous development of PEEP ?
  insufficient expiratory time
• Total PEEP Set PEEP Auto-PEEP
• Air trapping occurs when
• IE ratio ? (I gt E)
• There is incomplete Exhalation with normal IE
  (12 to 14)
• Auto-PEEP ? ? WOB

73
Unintentional Auto-PEEP

• Same physiological effect as set/extrinsic PEEP
• A triggering effort to overcome auto-PEEP is
  required to generate spontaneous breaths
• ? Risk of barotrauma

• ? Caution Detect unintentional PEEP to avoid
  potential adverse effects
• The pressure at the end of expiration using the
  expiratory hold should return to baseline (to
  either Zero cmH2O or the preset PEEP Level)
• Hint excessive inspiratory trigger ? RR
• Adjust ventilator settings
• ? inspiratory time (IE ratio) or ? peak flow
• ? preset RR or VT

74
Basic Ventilator Parameter Settings
75
Nursing Management

• Mechanical Ventilation-Specific Monitoring
  Interventions
• Improve Ventilation Oxygenation
• Acid-Base, Electrolyte Fluid Balance
• Care of ETT Ventilator Circuit
• Troubleshooting of Common Ventilator Alarms
• Cardio-Pulmonary Assessments
• Pharmacotherapy
• Sedation
• Bronchodilators
• Vasoactive Drug

76
Nursing Management

• Early Detection of Complications
• Hypoxemia
• Pneumothorax
• Nosocomial Pneumonia
• ETT Blockage
• Pulmonary Embolism
• Broncho-fistula

77
ETT Ventilator Circuit Management

• Patency
• Proper Placement Connection
• Infection Control
• Frequency of Circuit Change /?Disposable Circuit
  
• ?Scavenging System of Expired Gas
• Oral Hygiene
• Humidification Temperature
• Heat Moist Exchanger (HME)
• Suctioning
• ?Close-Suction Technique/Bagging

78
ETT Ventilator Circuit Management

• Familiarize yourself with the particular model of
  ventilator that is in use in your unit
• Perform ongoing assessments of the
  patient-ventilator system to ensure the patients
  safety, which is based on the patients response
  to the machine. Check that
• Alarm limits are appropriate
• Ventilator settings are consistent with the
  physicians orders
• Troubleshooting timely interventions to
  ventilator alarms and after the ventilator
  parameter changes
• ? NEVER ignore or disable the alarms or leave
  patient unattended when the alarm silence is
  activated. Be alert for potential problems

79
Common Alarms Possible Causes Actions
High Pressure Limit Suction for secretions Check for ETT blockage or biting of the tube Note the patency of the ventilator tubings or condensation of water if applicable Check the breath sounds for bronchial spasms Check Minute Volume Sp02 for adequate ventilation oxygenation Evaluate the adequacy of sedation if applicable Assess the level of consciousness or cooperation
Low Inspiratory Pressure Check for leaks or disconnections Assess the exhale TV whether there is adequate chest expansion or air entry
High Rate Check the total RR (Preset Spontaneous) Evaluate hypoxia or metabolic acidosis Assess increased metabolic demand or sepsis Note the anxiety level of the client or whether there is irritation from the artificial airway secretions Review the set sensitivity level
80
Common Alarms Possible Causes Actions
Low Exhaled Volume or Low Minute Volume Check for air leaks Note the volume that is associated with Mandatory/Assist/Spontaneous Breaths for poor inspiratory effort or fatigue during weaning Set a low exhale tidal volume limit in relation to spontaneous breaths
High PEEP Level Check the baseline pressure at the end of expiration or use an expiration hold Check the IE ratio for sufficient expiration time
Apnoea Evaluate poor respiratory effort. Assess brain stem dysfunction due to drug poisoning or increase intracranial pressure Check apnoea parameters intervals See if this is associated with sleep
? Check the alarm limit settings whether the ventilator has malfunctioned if appropriate interventions have been used on the patients all other causes have been ruled out ? Check the alarm limit settings whether the ventilator has malfunctioned if appropriate interventions have been used on the patients all other causes have been ruled out
81
General Nursing Management

• Oral Care
• Alternate ETT to bilateral mouth corners
• Note ulcers protect with duoderm, particularly
  when cotton tapes is used for fixation where
  copious secretions exist
• Be c,autious of throat irritation which triggers
  an gag reflex, coughing abundant secretions

82
General Nursing Management

• Nutrition
• Hypermetabolic Status Impairs Respiratory muscle
  structure function
• ? CO2 Production ? ? Ventilatory Workload
• Physical Mobility Comfort
• Nurse-Client-Family Interactions
  Decision-Making

83
ETT Ventilator Circuit Management

• Ventilator Standby
• (with a Heat Moist Exchanger HME, close
  suctioning catheter Steri-cath test lung)

84
ETT Ventilator Circuit Management
High-Quality Bacterial Filter in the Heat--Moist
Exchanger HME
Disposable Ventilator Tubing
Close-Suction Catheter
? In clients with infectious diseases such as
Severe Acute Respiratory Syndrome (SARS), these
devices are preferred to conventional ventilator
accessories such as humidifier cascades or the
open-suction method
85
Oral Endotracheal Tube Care
86
Conventional Humidification Cascade

• The designs of humidifiers vary in different
  ventilator models. Basically gas is bubbled
  through a water reservoir with filter heated to
  the desired temperature.
• Nosocomial infection is prevented by using
  sterile water.
• However, a heating wire in the inspiratory limb
  to prevent water condensation, refilling water in
  a humidifier emptying the condensed moisture is
  required.
• HME Humidifier will not be used at the same
  time!

87
Conventional Humidification Cascade
Sterile Water for Irrigation may be set up with
an infusion set attached in here for refilling
to minimize having to disconnect the circuit
In this model, filter paper will be used
wrapped around this heating device
88
Conventional Humidification Cascade
Suction can be applied to this opening to vacuum
away condensed water to avoid having to
disconnect the circuit
89

• Principles of the Heat Moist Exchanger HME
• The material in the HME has formed a large
  surface area, trapping heat moisture from the
  exhaled gases that pass through it. This is
  retained or condensed in the device and
  rebreathed by the patient.

Advantages Disadvantages
Simple to use can be applied with disposable ventilator tubing, also cost-effective HME increases the dead space of the ventilation circuitry as well as the flow resistance
Minimizes water condensation in the circuit Not suitable for clients with hypothermia, dehydration or tenacious secretions
90
(No Transcript)
91
Common Hazards Complications associated with
Mechanical Ventilation
92
Weaning Stages Progression
Lynn-McHale D J Carlson K K (ed) 2001 AACN
Procedure Manual for Critical Care. 4th ed
Philadelphia W B Saunders.
93
Weaning Extubation Criteria
94
Weaning Strategies

• Balance the WOB the Rest of the Respiratory
  Muscles
• Enhance the Strength Endurance of the
  Respiratory Muscles by high pressure-low volume
  work
• Alternatie weaning trials (e.g. CPAP or T-piece/
  Flow-by) complete rests for the ventilatory
  muscle (e.g. SIMV or High Level PS)
• Progressively lengthen supported ventilation
  from Absolute Ventilator-dependent Modes
• Exercise to avoid muscle fatigue
• Determine Weaning Trial Tolerance

• Abrupt Termination of Ventilatory Support
• Client on Mechanical Ventilation for a
  relatively short period
• Client substantial recovered from respiratory
  failure

95
Extubation

• Adequate Airway Protection
• Desired Level of Consciousness
• Manual Resuscition Re-intubation Equipment
  Standby
• Monitor Persistent Adverse Signs Respiratory
  Status (despite appropriate interventions)
• Tachypnea or Breathing Difficulties
• Desaturation (SpO2 ? 90)
• Tachycardia or BP gt 110 Baseline
• Paradoxical or Asymmetric Chest Movements
• Stridor

• Planned Extubation indicators to assess
  successful extubation
• Unplanned Extubation criteria to assist
  decision-making on Re-intubation

96
Further Readings on Ventilation Modes Strategies
In Hong Kong, clients on mechanical ventilation
may be nursed in general acute care settings in
some of the hospitals. Therefore, it is extremely
important for us to familiarize ourselves with
conventional mechanical ventilation salient
nursing care. Understanding the basic
ventilation principles relating clinical
progress to the diversified ventilation mechanism
may help to justify nursing assessment actions.
97
Sophisticated ventilation modes strategies have
advanced rapidly to meet the needs of clients
optimize clinical outcomes. Different ventilator
models vary or have distinct ventilation modes
are available, particularly in the critical care
arena, you have to familiarize yourself with the
corresponding ventilator type that used in your
particular unit. The following part of this
module is a brief outline of miscellaneous
ventilation modes for pressure control in
critical care unit. Broaden your scope of
learning by exploring the application of these
ventilation modes if you are interested.
98
Other Ventilation Modes
99
Pressure Control

• Key Features
• Flow cycled
• Constant preset pressure
• VT varies
• Preset minute volume to determine minimal
  ventilation support
• IRV - Inverse IE ratio (1.11 or 1.71)
  attained by setting the inspiration time or
  inspiration inspiration pause time
• Sensitivity is set where spontaneous breaths are
  NOT ALLOWED
• Basic ventilation modes could be applied
  (depending on the ventilator models), e.g.,
  PCA/C
• Preset the amount of augment pressure for
  spontaneous breaths

100
Pressure Control Inverse Ratio Ventilation 1
101
Pressure Control Inverse Ratio Ventilation 2
102
Special Ventilation Modes
103
Special Ventilation Therapies
104
References

• Chang D W 2001 Clinical Application of
  Mechanical Ventilation. 2nd ed. Africa Delmar
  Thomson Learning.
• Cairo J M Pilbeam S P 1999 Mosbys Respiratory
  Care Equipment. 6th ed. St Louis Mosby.
• Darovic G O 2002 Haemodynamic Monitoring
  Invasive and Noninvasive Clinical Application.
  3rd ed. Philadelphia W B Saunders.
• French W A 2000 Case Profiles in Respiratory
  Care. 2nd ed. Africa Delmar Thomson Learning.
• Hudak C M, Gallo B M Morton P G (ed) 2002
  Critical Care Nursing A Holistic Approach. 7th
  ed Philadelphia Lippincott.
• Milano J (ed)1998 Applied physiology in
  respiratory mechanics. New YorkSpringer-Verlag.

105
References

• Marino P L 1998 The ICU Book. 2nd ed Baltimore
  Lippincott.
• Mishoe S C Welch M A Jr 2002 Critical Thinking
  in Respiratory Care A Problem-Based Learning
  Approach. New York McGraw Hill.
• MuirJ F, Ambrosino N Simonds A K (ed) 2001
  Noninvasive Mechanical Ventilation. European
  Respiratory Society.
• Pierce L N B 1995 Guide to Mechanical
  Ventilation and Intensive Respiratory Care.
  Philadelphia W B Saunders.
• Wiegand, L-M D. J. Carlson, K. K. (Eds.)
  (2005). American Association of Critical-Care
  Nurses AACN Procedure Manual for Critical Care.
  (5th ed.). Philadelphia W B Saunders.

106
e-Book

• Lippincott Clinical Choice
• Harwood-Nuss, A., Wolfson, A. B., Linden, C.
  H., Shepherd, S. M. Stenklyft, P. H. (ed)
  (2001) The Clinical Practice of Emergency
  Medicine. Philadelphia Lippincott Williams
  Wilkins.
• Chapter 130 Acute respiratory insufficiency
• Marino, P. L. (1998) The ICU Book. (2nd ed)
  Philadelphia Lippincott Williams Wilkins.
• Section VI, Chapter 21-25 Acute Respiratory
  Failure
• Section VII, Chapter 26-29 Mechanical Ventilation

107
Journals

• Acton R, Hotchkiss J R Jr Dries D J 2002
  Noninvasive Ventilation. TRAUMA Vol 53 (3)
  593-601
• Berry B E Pinard A E 2002 Assessing tissue
  oxygenation. Critical Care Nurse. Vol 22 (3)
  22-34
• Boyer A, Thiéry G, Lasry S, Pigné E, Salah A, de
  Lassence A, Dreyfuss D Ricard J 2003 Long-term
  mechanical ventilation with hygroscopic heat and
  moisture exchangers used for 48 hours A
  prospective clinical, hygrometric, and
  bacteriologic study. Critical Care Medicine Vol 3
  (3) 823-829
• Brochard L 2002 Noninvasive Ventilation for
  Acute Respiratory Failure. JAMA Vol 288 (8)
  932-935
• Bresnahan M 2000 Liquid ventilation a future
  modality? AUSTRALIAN CRITICAL CARE Vol 1 (3)
  104-108
• Dries D J 1997 Weaning form Mechnical
  Ventilation. TRAUMA Vol 43 (2) 372-384

108
Journals

• Evans T 2000 Neuromuscular blockade When and
  how. RN Vol 63 (5) 56-61
• Grove P 2000 Endotracheal tube stability in the
  resuscitation environment. AUSTRALIAN CRITICAL
  CARE Vol 13 (1) 6-8
• Hess D 2001 Ventilator Modes Used in Weaning.
  CHEST Vol 120 (6) Supplement 474-476S
• Horne C Derrico D 1999 Mastering ABGs.
  American Journal of Nursing Vol 99 (8) 26 32
• Henderson N 1999 Mechanical Ventilation. Nursing
  Standard Vol 13 (44) 49-54
• Jevon P Ewens B 2001 Assessment of a
  breathless patient. Nursing Standard Vol 15 (16)
  48 -55

109
Journals

• LHer E 2003 Noninvasive mechanical ventilation
  in acute cardiogenic pulmonary edema. Current
  Opinion in Critical Care Vol 9 (1) 67-71
• Mutlu G M Mutlu E A 2001 GI Complications in
  Patients Receiving Mechanical Ventilation.
  CHEST, Vol 119 (4) pp1222-1241
• Navalesi P Costa R 2003 New modes of
  mechanical ventilation Proportional assist,
  neurally adjusted ventilatory assist, and fractal
  ventilation. Current Opinion in Critical Care Vol
  9 (1) 51-58
• Perkins L Shortall S P 2000 Ventilation
  Without Intubation. RN Vol 63 (1) 34-39
• Spritzer C J 2003 Unravelling the mysteries of
  mechanical ventilation A helpful step-by-step
  guide. Journal of Emergency Nursing Vol 29 (1)
  29-36
• Sasidhar M, Papa-Kanaan, J Waxman A 2003
  Haemodynamic Impact of Mechanical Ventilation in
  the Acute Respiratory Distress Syndrome. Clinical
  Pulmonary Medicine Vol 10 (3) 154-161

110
Journals

• Sasidhar M, Papa-Kanaan, J Waxman A 2003
  Haemodynamic Impact of Mechanical Ventilation in
  the Acute Respiratory Distress Syndrome. Clinical
  Pulmonary Medicine Vol 10 (3) 154-161
• Thomas L 2003 Clinical Management of Stressors
  Perceived by Patients on Mechanical Ventilation.
  AACN Clinical Issues Vol 14 (1) 73-81
• Takeuchi M, Willians P, Hess D Kacmarek R 2002
  Continuous Positive Airway Pressure in
  New-generation Mechanical Ventilators A Lung
  Model Study. Anesthesiology Vol 96 (1) 162-172
• Murray T A Patterson L A 2002 Prone
  positioning of trauma patients with acute
  respiratory distress syndrome and open abdominal
  incisions. Critical Care Nurse. Vol 22 (3) 52-58
• Weisman I 1999 Advances in Respiratory
  Monitoring During Mechanical Ventilation. CHEST
  Vol 116 (5) 1416-1425

111
Acknowledgements

• Special thanks to the undergraduates in the
  part-time Bachelor of Science in Nursing in the
  School of Nursing of The Hong Kong Polytechnic
  University. They kindly offered the clinical
  photos in their project presentation for use in
  this module
• . Chan K M, Chan S M, Chan S W V, Lee K M, Ngan S
  F, Yip N S, Yeung S K, Lai L T 2003 BiPAP
  Theory and ABG Interpretation. Unpublished
  Student Project School of Nursing, The Hong Kong
  Polytechnic University
• I would like to extend my thank to the
  undergraduate students, Mr On Sai Lok, Mr Wong
  Ting Fai Yu Chit. They role-modelled clinical
  photos also in the Close-Circuit Suction
  video. Further to this, special thanks to the
  Schools laboratory technician Ms So Kit Ying in
  her effort to facilitate the process.
• Their effort contribution greatly facilitate
  learning in this subject.