RT 230

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RT 230

• Unit A-
• Indication, Setup and Monitoring of CMV

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Indications for CMV

• Apnea
• Acute ventilatory failure A PCO2 of more than
  50mmHg with a pH of less than 7.25
• Impending acute ventilatory failure
• Based on lab data and clinical findings
  indicating that pt is progressing towards
  ventilatory failure
• Quick tip
• acute hypercapnic failure ph drops 0.8 for every
  10mm hg rise in co2
• chronic hupercapnic ph drops 0.03 for every 10
  mmhg rise in co2

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• Clinical problems often resulting in impending
  ventilatory failure
• Pulmonary abnormalities
• RDSRespiratory Distress Syndrome
• Pneumonia
• Pulmonary emboli
• Mechanical ability of lung to move airmuscle
  fatigue
• Ventilatory muscle fatigue
• Chest injury
• Thoracic abnormalitiesscoliosis, kyphoscoliosis
• Neurologic diseaseGB, MG
• Pleural diseasepleurasy

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• Clinical evaluation
• Vital signs Pulse and BP increase
• Ventilatory parameters
• VT decreases
• RR increases
• Accessory muscle use increases
• Paradoxical breathing (abdomen out, rib cage in)
• Retractions may be noted
• Development of impending acute vent failure may
  demonstrate
• Progressive muscle weakness in pt with Neurologic
  disease
• Increasing fatigue

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• ABGs demonstrating a trend toward failure
• 9am 10am 11am 12pm 1pm
• pH 7.58 7.53 7.46 7.38 7.35
• PCO2 22 28 35 42 48
• HCO3 21 22 23 24 24
• PO2 60 55 50 43 40

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Non-responsive hypoxemia

• PaO2 less than 50 on an FIO2 greater than 50
• PEEP is indicated
• REFRACTORY HYPOXEMIA

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Physiologic Effects of Positive Pressure
Ventilation

• Increased mean intrathoracic pressure
• Decreased venous return
• Thoracic pump is eliminated
• Pressure gradient of flow to right side of heart
  is decreased
• Right ventricular filling is impaired
• Give fluid
• Decreased cardiac output
• Caused by decreased venous return
• Give drugs and fluid
• Monitor I and O. Normal urine output 1000-1500
  cc/24 hours

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THORACIC PUMP

• The "thoracic pump" is the thoracic cavity, the
  diaphragm, the lungs, and the heart.
• The diaphragm moves down, pressure in the cavity
  decreases and venous blood rushes through the
  vena cava via the right heart into the lungs.
  Pulmonary blood vessels expand dramatically,
  filling with blood, air and blood meeting across
  the very thin alveolar surface. The deeper the
  inhalation, the more negative the pressure, the
  more blood flows, and the fuller the lungs
  become.

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THORACIC PUMP

• As the diaphragm moves up the pressure in the
  thoracic cavity reverses. Pulmonary blood vessels
  shrink ejecting an equal volume of blood out of
  the pulmonary veins into the left heart. The left
  heart raises the pressure and checks and
  regulates the flow. The more complete the
  exhalation, the more positive the pressure
  becomes and the more blood is ejected from the
  lungs.
• Decrease exhalation, more pressure in cavity
  decrease CO

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Effects of ppv cont.

• Increased intracranial pressure
• Blood pools in periphery and cranium because of
  decreased venous return
• Increased volume of blood in cranium increases
  intracranial pressure
• Decreased urinary output
• PPV could cause 30-50 decrease renal output
• Decreased CO results in decreased renal blood
  flow
• Alters filtration pressures and diminishes urine
  formation
• Decreased venous return and decreased atrial
  pressure are interpreted as a decrease in overall
  blood volume
• ADH is increased and urine formation is decreased

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ADHVASOPRESSIN

• Roughly 60 of the mass of the body is water, and
  despite wide variation in the amount of water
  taken in each day, body water content remains
  incredibly stable. Such precise control of body
  water and solute concentrations is a function of
  several hormones acting on both the kidneys and
  vascular system, but there is no doubt that
  antidiuretic hormone is a key player in this
  process.
• Antidiuretic hormone, also known commonly as
  arginine vasopressin

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• The single most important effect of antidiuretic
  hormone is to conserve body water by reducing the
  loss of water in urine. A diuretic is an agent
  that increases the rate of urine formation.
• high concentrations of antidiuretic hormone cause
  widespread constriction of arterioles, which
  leads to increased arterial pressure.
• Retention of fluids will cause EDEMA

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Effects of ppv cont.

• Decreased work of breathing
• Force to ventilate is provided by the ventilator
• Increased deadspace ventilation
• Positive pressure distends conducting airways
  inhibits venous return
• The portion of VT that is deadspace increases
• Greater percentage of ventilation goes to apices
• Increased intrapulmonary shunt
• Ventilation to gravity dependent areas is
  decreased
• Perfusion to gravity dependent areas increase
• Shunt fraction increases from 2-5 to 10

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A pulmonary shunt is a physiological condition
which results when the alveoli of the lung are
perfused with blood as normal, but ventilation
(the supply of air) fails to supply the perfused
region. In other words, the ventilation/perfusion
ratio (the ratio of air reaching the alveoli to
blood perfusing them) is zero. A pulmonary shunt
often occurs when the alveoli fill with fluid,
causing parts of the lung to be unventilated
although they are still perfused. Intrapulmonary
shunting is the main cause of hypoxemia
(inadequate blood oxygen) in pulmonary edema and
conditions such as pneumonia in which the lungs
become consolidated.
The shunt fraction is the percentage of blood put
out by the heart that is not completely
oxygenated. A small degree of shunt is normal and
may be described as 'physiological shunt'. In a
normal healthy person, the physiological shunt is
rarely over 4 in pathological conditions such
as pulmonary contusion, the shunt fraction is
significantly greater and even breathing 100
oxygen does not fully oxygenate the blood.1
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Effects of ppv cont.

• Respiratory rate, VT, Inspiratory time, and flow
  rate can be controlled
• May cause stress ulcers and bleeding in GI tract

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Complications of Mechanical Ventilation

• Complications related to pressure
• Ventilator-associated lung injury (VALI)
• High pressures are associated with barotrauma
• Pneumothorax, pneumomediastinum,
  pneumopericardium, subcutaneous emphysema
• Pneumothorax has decreased chest movement,
  hyperresonance to percussion, on affected side
• If tension pneumothorax medical emergency
• Relieved by needle insertion, then chest tube
• Use 100 oxygen to speed reabsorption.

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Placing patient on CMV

• Establish airway
• Select VT 8-12ml/kg of ideal body weight
• Select mode - a/c sensitivity at minimal to not
  self cycle
• Set pressure limit 10cmH2O above delivery
  pressure
• Set sigh volume 1-1/2 to 2 times VT
• Sigh pressure 10cmH2O above sigh delivery
  pressure
• Rate as ordered
• PEEP as ordered exp. resist, insp. hold, etc.
• Set spirometer 100 cc less than patient volume
• check for function (turn on)

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Modes

• Control
• All of WOB is taken over by ventilator
• Sedation is required
• Control mode is useful
• During ARDS, especially if high PEEP is required
  or inverse IE ratio
• Assist
• Patient is able to control ventilatory rate
• Should not be used for continuous mechanical
  ventilation if pt is apneic

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• Assist/control
• Pt able to control vent rate as long as
  spontaneous rate gt backup rate
• Machine performs majority of WOB
• Sedation is often required to prevent
  hyperventilation
• Is useful during early phase of vent support
  where rest is required
• Useful for long term for pt not ready to wean
• SIMV
• In between positive press breaths pt can breathe
  spontaneously
• Useful for long term for pt not ready to wean
• Used as weaning technique for short-term vent
  dependent pt

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• PS
• Vent functions as constant pressure generator
• Positive pressure is set
• Pt initiates breath, a predetermined pressure is
  rapidly established
• Pt ventilates spont, establishes own rate, VT,
  peak flow and IE
• Can be used independently/CPAP/SIMV
• Indicated to reduce work imposed by ETT, 5 to
  20cm H2O
• Can be used for weaning
• A set IPS (12ml/kg VT) achieved by adjusting IPS
  level then slowly reducing as clinical status
  improves
• To overcome resistance of ETT, IPS should meet
  Raw
• To determine amount of PS needed (PIP Plateau
  pressure) / Ventilatory inspiratory flow x
  spontaneous peak inspiratory flow

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• IBWEstimated ideal body weight in (kg)Males
  IBW 50 kg 2.3 kg for each inch over 5
  feet.Females IBW 45.5 kg 2.3 kg for each
  inch over 5 fee.
• 1 Kilogram 2.20462262 Pounds

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Monitoring CMV

• Observation
• Look at patient!
• Make a good visual assessment
• Start with patient, trace circuit back to
  ventilator
• Check and drain tubing
• Check connections
• Check patient
• Suctioning, position, etc.
• BP
• Spontaneous RR
• Heart rate and all vital signs

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• Check machine settings
• VT (set, exhaled, corrected)
• f (assisted, set, spontaneous)
• Pressure limit 10 above delivery pressure
• PEEP if applicable Check BP!
• Peak Insp. Pressure (PIP) Keep as low as
  possible
• IE ratio for proper flow
• FiO2 Keep as low as possible to prevent Oxygen
  Toxicity yet keep them adequately oxygenated
• Check all apnea alarms and settings.
• Check set VT to exhaled VT for any lost volumes
• If difference is greater than 100 cc, check for
  leak.

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Compliance

• Measures distensibility of lung how much does
  the lung resist expansion.
• Relationship between Volume and Pressure
• High compliance equals lower PIP thus easier
  ventilation and less side effects of CMV

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• Disease states resulting in low compliance
  include the Adult Respiratory Distress Syndrome
  (ARDS), pulmonary edema, pneumonectomy, pleural
  effusion, pulmonary fibrosis, and pneumonia among
  others.
• Emphysema is a typical cause of increased lung
  compliance.

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You must know

• Dynamic VT (corrected or exhaled)
• PIP PEEP
• Always subtract out PEEP
• Consistently use exhaled or corrected VT
• Used to assess volume/pressure relationships
  during breathing any changes in RR will effect
  it
• CDYN decreases as RR increases which may cause
  V/Q mismatch which may cause hypoxemia
• May reflect change due to change in flow due to
  turbulence instead of compliance
• Normal 30 40 cmH2O

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Very important

• Static VT (corrected or exhaled)
• Plateau PEEP
• Always subtract out PEEP
• Always consistently use either VT exhaled or VT
  corrected
• Will not change due to change in flow, more
  accurate
• Measured pressure to keep airways open with no
  gas flow.
• Normal values very with pt, but usually above 80
  cmh2o will show lung overdistention

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• Importance
• to follow trends in patient compliance
• Decreased C stiffer lung less compliant
  higher ventilating pressures you need a
  ventilator with high internal resistance to
  deliver volumes using square wave.
• High compliance possible Emphysema

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Static vs Dynamic Compliance

• Decrease in CDYN with no change in CST indicates
  worsening airway resistance
• Causes
• Bronchospasm
• Secretions
• Kinked/Occluded ETT
• Inappropriate flow and/or sensitivity settings
• If both CDYN and CST worsen, not likely to be an
  airway problem
• Causes
• Pulmonary Edema
• ARDS
• Tension Pneumothorax
• Atelectasis
• Fibrosis
• Pneumonia
• Obesity
• Patient Position

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• RAW PIP Pplat
• Flow (L/sec.)
• Airway Resistance
• Impedance to ventilation by movement of gas
  through the airways thus the smaller the airway
  the more resistance which will increase WOB
  (causing respiratory muscle and patient fatigue)
• Example ETT, Ventilator Circuit, Bronchospasm

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• Airway Resistance Compliance
• Decreased Compliance Increased Airway
• Resistance High PIP, Decreased Volumes and
  significant increase in WOB
• Very difficult to wean a patient until problems
  are resolved

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Patient stability

• Vital signs
• Pulse normal, weak, thready, bounding, rate,
  etc.
• BP hypo/hypertensive directly related to CO
• Respirations tachypnea, bradypnea, hyperpnea,
  hypopnea, rate, etc.
• Color dusky, pale, gray, pink, cyanotic
• Auscultation - bilateral, etc.
• Are they bilateral, amount of air moving, rales,
  rhonchi or wheezing
• Are they Vesicular (normal) or Adventitious
  (abnormal)
• Describe what you hear fine, course,
  high-pitched, low-pitched, etc.
• And the location where you heard it bilateral
  bases, posterior bases, right upper anterior
  lobe, laryngeal, upper airway, etc.

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Hemodynamic monitoring

• BTFDC
• Also known as
• Balloon Tipped Flow Directed Catheter
• Swan-Ganz Catheter
• Pulmonary Artery Catheter
• Done by inserting a BTFDC into R atrium, thru R
  ventricle, and into pulmonary artery
• SvO2 is drawn from the distal port of a BTFDC
• Used to monitor tissue oxygenation and the amount
  of O2 consumed by the body

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Catheters and Insertion Sites
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PA Pressure Waveforms
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• CVP 
• Monitors fluid levels, blood going to the right
  side of heart
• Normal 2 6 mmHg (4 12 cmH2O)
• Increased CVP right sided heart failure (cor
  pulmonale), hypervolemia (too much fluid)
• Decreased CVP hypovolemia (too little fluid),
  hemorrhage, vasodilation (as occurs with septic
  shock)

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• PAP
• Pulmonary Artery Pressure B/P lungs
• Monitors blood going to lungs via Swan-Ganz
  catheter (BTFDC)
• Normal 25/8 (mmHg)
• Increased PAP COPD, Pulmonary Hypertension, or
  Pulmonary Embolism
• PCWP
• Pulmonary Capillary Wedge Pressure monitors blood
  moving to the L heart
• Balloon is inflated to cause a wedge
• Normal PCWP 8 mmHg
• Range is 4 12 mmHg
• Increased PCWP L heart failure, CHF
• Measure backflow resistance

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• Cardiac Output
• Expressed as QT or CO (QT Greek alphabet, 1050
  BC scientist used qt had cardiac output
  expression)
• Normal 5 LPM
• Range 4 8 LPM
• Decreased CO CHF, L heart failure, High PEEP
  effects
• I O
• Needs to be monitored closely to prevent fluid
  imbalance due to increased ADH production and
  decreased renal perfusion
• Fluid imbalance can develop into pulmonary edema
  and hypertension

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(No Transcript)
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Cardiac Output (CO)

• The amount of blood pumped out of the left
  ventricle in 1 minute is the CO
• A product of stroke volume and heart rate
• Stroke volume amount of blood ejected from the
  left ventricle with each contraction
• Normal stroke volume from 60 to 130 ml
• Normal CO from 4 to 8 L/min at rest
• Fick CO Vo2/Cao2-Cvo2
• C(a-v)O2 could decrease if CO is increased due to
  less oxygen needs to be extracted from each unit
  of blood that passes

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Fick MethodThe Fick method requires that you be
able to measure the A-V oxygen content difference
and requires that you be able to measure the
oxygen consumption. An arterial blood gas from a
peripheral artery provides the blood for the CaO2
measurement or calculation while blood from the
distal PA port of a Swan-Ganz catheter provides
the blood for the CvO2 measurement or calculation
Dilution methods mathematically calculate (using
calculus) the cardiac output based on how fast
the flowing blood can dilute a marker substance
introduced into the circulation normally via a
pulmonary artery catheter. (injecting a dye in
prox port of Swanz. Not really used anymore due
to infections
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Measures of Cardiac Output and Pump Function

• Cardiac index (CI)
• Determined by dividing the CO by body surface
  area
• Normal CI is 2.5 to 4.0 L/min/m2
• CI measurement allows a standardized
  interpretation of the cardiac function
• True cardiac output compared to each persON

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Measures of Cardiac Output and Pump Function
(contd)

• Cardiac work
• A measurement of the energy spent ejecting blood
  from the ventricles against aortic and pulmonary
  artery pressures
• It correlates well with the amount of oxygen
  needed by the heart
• Normally cardiac work is much higher for the left
  ventricle

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Measures of Cardiac Output and Pump Function
(contd)

• Ventricular stroke work
• A measure of myocardial work per contraction
• It is the product of stroke volume times the
  pressure across the vascular bed
• Ventricular volume
• Estimated by measuring end-diastolic pressure

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Measures of Cardiac Output and Pump Function
(contd)

• Ejection fraction
• The fraction of end-diastolic volume ejected with
  each systole normally 65 to 70 drops with
  cardiac failure

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Determinants of Pump Function

• Preload
• Created by end-diastolic volume
• The greater the stretch on the myocardium prior
  to contraction the greater the subsequent
  contraction will be
• When preload is too low, SV and CO will drop
• This occurs with hypovolemia
• Too much stretch on the heart can also reduce SV

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Determinants of Pump Function

• Afterload
• Two components peripheral vascular resistance
  and tension in the ventricular wall
• Created by end systolic volume
• Increases with ventricular wall distention and
  peripheral vasoconstriction
• As afterload increases, so does the oxygen demand
  of the heart
• Decreasing afterload with vasodilators may help
  improve SV but can cause BP to drop if the blood
  volume is low

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Ventilation Patient Parameters

• Spontaneous VT
• Is it adequate for patient?
• Spontaneous volumes should be between 5 8 ml/Kg
  of Ideal Body Weight (IBW)
• Spontaneous VC
• 10 15 ml/Kg IBW
• NIF/MIP/MIF/NIP
• -20 to -25 cmH2O within 20 seconds

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ABGs

• PaO2 represents oxygenation adjust with PEEP or
  FiO2
• PaCO2 represents ventilation adjust with VT or
  RR
• pH represents Acid/Base status
• pH acid High CO2 (respiratory cause) or low HCO3
  (Metabolic cause)
• pH alkaline Low CO2 (respiratory cause) or high
  HCO3 (Metabolic cause)

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• Draw ABGs
• To stabilize
• With any change in ventilator settings change
  only one vent setting at a time
• With any change in patient condition

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Ventilator alarms

• Appropriate for each patient
• Usually 10 higher/lower than set parameter
• For pressure and RR settings
• VT alarms 100 ml higher/lower than set VT
• Adjust all alarms for patient safety.

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X-ray when indicated for

• Tube placement 2 4 cm above carina
• Possible pneumothorax
• To check for disease process reversal, or lack
  of, for treatment purposes and weaning

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Frequency of ventilator checks

• Must be done as often as required by the patients
  condition unstable patients continuous to hourly
• In general patients and ventilators need
  evaluation Q1-Q4h
• With every vent check, patient assessment should
  take place
• Use VT exhaled for calculations.
• Corrected VT exhaled vt-tubing lost volume
• Tubing volume lost factor 1-8 cc x pressure
• Exhaled vt 650 pip-peep x (3) 60
• 650-60590 corrected vt

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Waveform Analysis

• Three wave forms typically presented together
• Pressure
• Flow
• Volume
• Plotted versus time
• Horizontal axis is time
• Vertical axis is variable
• Other common wave forms
• Pressure vs Volume
• Flow vs Volume

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• Pressure vs Time Assessment
• Patient Effort Negative pressure deflection at
  beginning of inspiration indicates patient
  initiated breath
• Peak Plateau Pressures
• Adequacy of inspiratory flow If pressure rises
  slowly, or if curve is concave, flow is
  inadequate to meet patients demand.
• Flow vs Time Assessment
• Inspiratory flow patterns
• Air Trapping a.k.a. AutoPEEP expiratory flow
  fails to reach baseline prior to delivery of next
  breath

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• Airway Resistance
• Lower slope (smaller angle) indicative of high
  resistance to flow
• Steeper slope (greater angle) indicative of lower
  resistance to flow
• Also increased resistance manifests itself as
  decreased peak expiratory flowrate (depth of
  expiratory portion of flow pattern) with more
  gradual return to baseline as expiratory flow
  meets with resistance
• Bronchodilator increased peak expiratory flow
  rate with quicker return to baseline

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• Volume vs Time Assessment
• VT peak value reached during inspiration
• Air Trapping fails to reach baseline before
  commencement of next breath
• Identifying breath type
• Larger volumes mechanical breaths
• Smaller volumes spontaneous breaths

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• Pressure vs Volume Loop
• Volume on vertical axis
• Pressure on horizontal axis
• Positive pressure on right of vertical axis
• Indicates mechanical breath
• Application of positive pressure to the lung
• Tracing is in a counter-clockwise rotation

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• Subambient pressure to the left of the vertical
  axis
• Indicates a spontaneous breath
• Spontaneous inspiration is to the left of the
  vertical axis subatmospheric pressure at start
  of inspiration (Intrapulmonary pressure -3
  cmH2O)
• Spontaneous expiration is to the left of the
  vertical axis 3 cmH2O intrapulmonary pressure
  on expiration
• Tracing is in a clockwise rotation
• Useful in helping diagnosing
• Alveolar Overdistension looks like birds beak,
  or the Partridge Family symbol
• Increased RAW looks pregnant or fat
• Decreased compliance looks lazy or like its
  lying down

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• Flow vs Volume Loop
• Helpful in assessing changes in RAW, such as
  after the administration of a bronchodilator
• Flow on vertical axis
• Volume on horizontal axis
• Inspiration is top part of loop, expiration on
  bottom
• When RAW improved, expiratory flows are greater
  and the slope of the expiratory flow is greater

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• To determine patient effort, use the following
  curves
• Pressure vs Time
• Pressure vs Volume Loop
• Volume vs Time
• All show subambient drops in pressure/volume when
  patient initiates the breath

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• To determine Auto-PEEP, use
• Volume vs Time
• Flow vs Time
• Pressure vs Volume Loop
• For all curves, ask does the exhalation reach
  baseline before the next breath starts
• To determine the adequacy of inspiratory flow
• Pressure vs Time concave or slow rise to
  pressure means inadequate flow on inspiration
• Volume vs Time Too slow flow increased I
  Time decreased E-Time AutoPEEP
• Volume vs Pressure Slope is shallow, may look
  similar to loop associated with increased RAW

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• If you detect the patient actively working during
  mechanical breath, increase the flow to help meet
  the patients demand and decrease the WOB
• To assess changes in compliance, use
• Pressure vs Volume Loop
• Steeper slope increased compliance, or larger
  volume at lower pressure
• Shallow slope decreased compliance, or smaller
  volume at higher pressure

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• To assess changes in RAW, use
• Pressure vs Volume Loop
• Space hysteresis between inspiratory and
  expiratory portions of loop
• Bowed appearance inspiratory portion more
  rounded and distends toward the pressure axis
• Flow vs Volume Loop
• Observe peak flow on Flow-Volume Loop
• Increased RAW Decreased Peak Flow

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UNIT B

• Acute Critical Care

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PEEP/CPAP

• PEEP Positive End Expiratory Pressure
• Definition
• Application of pressure above atmospheric at the
  airway throughout expiration
• Goal
• To enhance tissue oxygenation
• Maintain a PaO2 above 60 mmHg with least amount
  of supplemental oxygen
• Recruit alveoli
• DECREASE (PA-a)02
• Dont forget (PA-a)02 will increase with v/q or
  shunt

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HOW TO ACHIVE CPAP/PEEP

• A. Exhaling through a spring tension diaphragm
• B. Exhaling through a column of water
• C. Exhaling through a partially inflated
  exhalation valve (mushroom type)
• D. A continuous flow through the circuit

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• Indications
• Cardiogenic pulmonary edema
• Left sided heart failure
• Prevents transudation of fluid
• Improves gas exchange
• ARDS
• Increases lung compliance
• Decreases intrapulmonary shunting
• Increases FRC
• Refractory hypoxemia
• PaO2 lt 50 mmHg with an FIO2 gt50
• Increase FRC
• Opens collapsed alveoli
• Increases reserve

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• Contraindications
• Unilateral lung disease
• Hypovolemia
• Hypotension
• Untreated pneumothorax
• Increased ICP
• Hazards
• All of the effects of CMV are magnified
• Increased intrathoracic pressure
• Decreased venous return
• Increased ADH
• Decreased blood pressure
• Decreased cardiac output
• Loss of thoracic pump
• Barotrauma

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• Physiological effects
• Baseline pressure increases
• Increased intrapleural pressures
• Increased FRCrecruiting collapsed alveoli
• Dead spaceincreased in non-uniform lung disease
  and healthy lungs by distending alveoli
• Increased alveolar volumes
• Can increase compliance
• Cardiovascular
• Decrease venous return
• Decrease cardiac output
• Decrease blood pressure

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• Decreases intrapulmonary shunt
• Increases mixed venous value (PvO2)--Drawn from
  pulmonary artery via Swan-Ganz
• Increased intracranial pressures
• Decrease in A-a gradient (A-a DO2)
• Increased PaO2
• Decrease in FIO2, which causes a decrease in PAO2

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Initiation and monitoring of PEEP

• Start off at 5 cmH2O and increase by 3 to 5 cmH2O
  increments
• Adjust sensitivity
• With an increase in baseline pressure the
  sensitivity must be increased or the patient will
  have to increase inspiratory effort to initiate a
  breath
• Monitor
• Blood pressure First thing you look at when
  adding PEEP
• Cardiac output Goal is least cardiac
  embarrassment with the best PaO2 and least FIO2
• Pulse
• If the patient is hypoxemic their heart rate is
  probably increased
• With addition of PEEP the hypoxemia should
  resolve and pulse should decrease to normal level
• PaO2 Goal is best PaO2 with the lowest possible
  FIO2

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Maintenance level of PEEP

• PEEP trial
• Used to determine best level of PEEP
• This is the pressure at which cardiac output and
  total lung compliance is maximized,the VD/VT is
  minimal, and the best PaO2 and PvO2, and the
  lowest P(A-a)O2 are obtained
• Optimal Peep
• Level at which physiological shunt (Qs/Qt) is
  lowest without detrimental drop in cardiac output
• A C(A-V)O2 of less than 3.5 vol should reflect
  adequate CO
• Ficks law CO VO2/C(a-v)O2
• Cardiac output and C(a-v)O2 are inversely related
• Best oxygenation with lease cardiac issues

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CPAP

• Physiologically the same as PEEP
• Used in spontaneously breathing patients
• Maintains continuous positive airway pressure
  during inspiration and expiration
• Accomplished by a continuous flow of gas or a
  demand valve
• System flow must be enough to meet patients peak
  inspiratory demands
• Used to treat OSA
• CPAP delivered via mask or nasal pillows
• No machine breaths, all spontaneous ventilation

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NPPV (BiPAP)

• Similar to CPAP
• Delivers two levels of pressure during the
  inspiratory-expiratory cycle
• Delivers higher pressure on inspiration
• Delivers lower pressure on exhalation
• Less resistance to exhalation

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• Two levels of pressure
• EPAP
• Constant pressure delivered during exhalation
• Same as CPAP
• Adjust for oxygenation
• IPAP
• Constant pressure delivered during inspiration
• Same as IPPB
• Adjust for ventilation
• The difference between the two pressures is known
  as pressure support

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• Used to treat OSA
• Better tolerated than traditional CPAP
• Delivered with mask or nasal pillows
• Used in acute respiratory failure
• Can prevent or delay intubation and CMV
• Improves ventilation and oxygenation
• Improves patient comfort

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Rules of putting patient on PEEP

• Obtain order
• Set-up PEEP and make additional changes (i.e.,
  sensitivity)
• Monitor patient for hazards, BP, CO if available
• Monitor for "optimal/best PEEP"
• 60-60 Rule to improve oxygenation increase fio2
  to 60 then start adding peep (to prevent o2
  toxicity). To remove peep go down to 60 and
  then start removing peep

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IMV/SIMV

• Definitions
• IMV Intermittent Mandatory Ventilation
• Patient receives set number of mechanical breaths
  from the ventilator. In between those breaths,
  the patient can take their own spontaneous
  breaths at a rate and VT of their choice.
• SIMV Synchronized Intermittent Mandatory
  Ventilation
• Same as IMV, except the mechanical breaths are
  synchronized with the patients spontaneous
  respiratory rate. Helps improve
  patient/ventilator synchrony and helps prevent
  breath stacking (where the vent delivers the
  machine set VT on top of the patients
  spontaneous VT)

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• IMV
• Advantages
• Prevents muscle atrophy makes patient assume an
  increasing, self-regulating role in their own
  respirations, helping to rebuild respiratory
  muscles
• Allows patient to reach baseline ABGs baseline
  means the patients baseline ABGs
• Chronic CO2 retainer ABGs do not have a normal
  PaCO2 of 40
• Decreases mean intrathoracic pressure the lower
  the IMV/SIMV rate, the lower the intrathoracic
  pressure
• Avoids decreased venous return lower
  intrathoracic pressure greater venous return
• Avoids cardiac embarrassment greater venous
  return less decrease in cardiac output and
  blood pressure

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• May avoid positive fluid balance
• Allows normalization of ADH production
• Helps avoid cardiac embarrassment
• Psychological encouragement
• Some patients may exhibit anxiety, especially
  those who have been on the vent for several days
  or weeks
• Do not tell the patient they will never need the
  vent again
• Some patients become encouraged by progress,
  being able to do more for themselves
• Weaning gradually re-evaluate if weaning takes
  several days

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• May allow decreased use of pharmacological agents
  e.g., morphine, diprivan, versed, etc.
• If patient is too sedated, wont be able to
  breathe spontaneously and participate in weaning
• May be the only way to correct respiratory
  alkalosis on patient who is over-breathing the
  vent in A/C mode
• Patients spontaneous VT will most likely be
  smaller than that of the set VT on mechanical
  ventilator

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Candidates for IMV/SIMV

• IMV/SIMV is great for weaning patient from CMV
• Allows patient to assume increased responsibility
  for providing own respirations, with diminishing
  mechanical support
• Allows patient to re-build respiratory muscle
  strength
• Patient must be stable. Not ideal for unstable
  patient. Consider patient unstable if
• Fever causes increased O2 consumption and
  increased CO2 production, thereby increasing WOB
• Unstable cardiac status
• Unresolved primary problem that caused them to be
  on the vent in the first place

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• Problems of IMV
• Fighting the ventilator patient becomes out of
  phase or synch with the ventilator
• Stacking of breaths is not necessarily a problem
• Patient will normally synchronize self with
  ventilator rate
• Patient disconnection from gas source (with
  external IMV circuit)
• Other problems of CMV

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• Benefits of SIMV Synchronized IMV
• Prevents stacking of breaths (pt can breath
  spontaneously through demand valve)
• May help patient to become in phase with vent
• Breath stacking could be prevented just by
  increase inspiratory flow

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Inspiratory Pressure Support (IPS)

• Commonly referred to simply as Pressure Support
• During spontaneous breathing, the ventilator
  functions as a constant pressure generator
• Pressure develops rapidly in the ventilator
  system and remains at the set level until
  spontaneous inspiratory flow rates drop to 25 of
  the peak inspiratory flow (or specific flow rate)
• This mode may be used
• Independently
• With CPAP
• With SIMV
• With any spontaneous ventilatory mode
• Not with any full support modes, such as Control
  or A/C

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• PS is used to overcome the increased resistance
  of the ET tube and vent circuit
• Pouiselles Law decrease the diameter of a tube
  by ½, increase the resistance of flow through
  that tube by 16 times
• If you apply/use PS, do not set less than 5 cmH2O
  of PS least amount needed to overcome
  resistance of ET tube and vent circuit
• If PS is set at a level higher than RAW, you will
  be adding to patient volumes, rather than just
  helping overcome the increased resistance from
  the ET tube and vent circuit
• Can be used to help wean patient from vent and
  help rebuild respiratory muscle strength

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Management of ventilators by ABGs

• Pressure Control Ventilation
• Can be used as CMV or SIMV
• In SIMV mode, the machine breaths are delivered
  at the preset pressure while the spontaneous
  breaths are delivered with PS
• PC-CMV (a.k.a., PCV) used to decrease shear
  forces that damage alveoli whenever the peak or
  plateau pressures meet or exceed 35cm H2O
• Help prevent damage to alveoli from excessively
  high ventilating pressures
• Shear forces damage alveoli when they collapse
  (because closing volumes are above FRC) and then
  are forced back open again with the next breath.
  Damage occurs as this cycle is repeated over
  time alveoli collapses, then is reinflated,
  collapses, reinflated, etc.

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• Also used when permissive hypercapnia is desired
  (treatment of ARDS)
• When the PaCO2 is allowed to rise through a
  planned reduction in PPV, which allows for a
  reduction in the mean intrathoracic pressure,
  which results in less incidence of barotrauma and
  other commonly associated complications of PPV
• The gradual increase in PaCO2 is accomplished by
  a reduction of the mechanical VT (by decreasing
  the pressure) and usually does not affect the
  oxygenation

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• PC-IRV Pressure Controlled Inverse Ratio
  Ventilation
• Pressure controlled ventilation with an IE ratio
  gt 11.
• Causes mean airway pressure to rise with the IE
  ratio
• Usually used on patients with severe hypoxemia
  where high FIO2s and PEEP have failed to improve
  oxygenation
• Causes intrinsic PEEP (a.k.a. auto-PEEP), which
  is what causes the mean airway pressure to
  increase, which is the mechanism for alveolar
  recruitment and improved arterial oxygenation

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• While an increase in oxygenation does occur at
  the lung, a resultant decrease in cardiac output
  (due to the increased mean intrathoracic
  pressures) may result in an overall decrease in
  tissue oxygenation. Care must be exercised to
  maintain adequate cardiac output in order to
  maintain adequate tissue oxygenation
• Because its not a natural way to breath
  (backwards from the way we normally breath), most
  patients must be either heavily sedated
  (Diprivan, Versed) or must be paralyzed with a
  paralytic drug (such as Pavulon or Norcuron)

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• APRV Airway Pressure Release Ventilation
• Related to PC-IRV except that patient breathes
  spontaneously throughout periods of raised and
  lowered airway pressure.
• APRV intermittently decreases or releases the
  airway pressure from an upper CPAP (IPAP) level
  to a lower CPAP (EPAP) level
• The airway pressure release usually lasts 1.5
  seconds or shorter, allowing the gas to passively
  leave the lungs to eliminate CO2
• IE ratio is usually gt 11, but differs from
  PC-IRV in that it allows spontaneous breathing
• Because patient is breathing spontaneously, there
  is less need for sedation

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• Usually has lower peak airway pressure than
  PC-IRV
• Originally proposed as a treatment for severe
  hypoxemia, but appears to be more useful in
  improving alveolar ventilation rather than
  oxygenation.

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End Tidal CO2 Monitoring (PETCO2)

• Measures CO2 level at end exhalation, when CO2
  levels are highest in exhaled breath
• Two methods of collection
• Sidestream typically used for non-intubated
  patients
• Mainstream typically used for intubated
  patients and more commonly seen and used
• Probe is placed between the patient wye of vent
  tubing and the patients ETT
• Infrared light measures CO2 levels
• Inspired gas should have value of zero
• PETCO2 content should be within 2 5 mmHg of
  patients PaCO2
• Difference will be greater on a patient with
  larger amounts of air trapping, e.g. Emphysema

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Capnometry (cont.)
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• End-tidal CO2 monitoring is for trending
• Not absolutecan vary from breath to breath
  similar to pulse oximetry
• Look at the trend. Is the patients PETCO2
  increasing or decreasing over a period of time?
  Similar activity should then be also occurring
  with the PaCO2
• When setup, correlate the PETCO2 readings with
  current ABGs PaCO2. This will give you an idea of
  how much less the PETCO2 is reading than the
  PaCO2, giving you a good idea of future trends of
  the PETCO2 will relate to the PaCO2

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Chest Tube Drainage Systems

• Chest tube placed high in thoracic cavity to
  drain air
• Second or third intercostal space at
  midclavicular line
• Incision made right over the rib
• Chest tube advanced towards anterior apex of
  lung.
• Chest tube placed low in thoracic cavity to drain
  fluid (e.g., pleural effusion)
• Placement is in fourth intercostal space (or
  lower) at midaxillary line
• Patient is placed lying on side with affected
  side up
• Once incision is made, tube is advanced
  posteriorly, toward the base of the lung so
  gravity can help drain the fluid

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• Three chamber chest tube drainage system is most
  common
• Left chamber is the suction control chamber
• Level of water determines how much suction is
  applied to the chest cavity, regardless of how
  much the suction is set on the suction regulator
  on the wall
• Middle chamber is the water seal chamber
• Usually no more than 2 cmH2O
• Too much and you increase difficulty of air or
  fluid to drain
• Too little and you risk an air leak

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• Bubbles in water seal indicate that a leak in the
  lung is still present
• Spontaneous breathing patients with leak will
  have bubbles on exhalation
• Intubated, mechanically ventilated patients with
  leak will have bubbles on inspiration
• Continuous bubbling could be a sign of a leak in
  your chest tube drainage system and must be
  corrected immediately!
• Clamp chest tube briefly where it exits patients
  chest. If bubbling stops, leak is in your patient
  (intrathoracic).
• If bubbling persists, then you must check your
  chest tube drainage system for leaks
• Move clamp down tubing in 10cm (approx. 4 inch)
  increments (working from patient to chest tube
  drainage system), briefly clamping as you go
  until bubbling stops
• Right chamber is the drainage collection chamber
• This is where the fluid drained from the patient
  is collected

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ALIAcute lung injury or ARDS

• Definition agreed upon in 1994 at the American
  European Consensus Conference on ARDS

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• ALI Definition a syndrome of acute and
  persistent lung inflammation with increased
  vascular permeability. Characterized by
• Bilateral radiographic infiltrates
• A ratio PaO2/FIO2 between 201 and 300 mmHg,
  regardless of the level of PEEP. The PaO2 is
  measured in mmHg and the FIO2 is expressed as a
  decimal between 0.21 and 1.00
• No clinical evidence of an elevated left atrial
  pressure. If measured, the PCWP is 18 mmHg or
  less

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• ARDS Definition same as ALI, except the hypoxia
  is worse. Requires a PaO2/FIO2 ratio of 200 mmHg
  or less, regardless of the level of PEEP. ARDS is
  ALI in its most extreme state
• Mortality rate between 40 and 60 --varies from
  source to source
• Down from about 20 years ago when ARDS was almost
  certain death sentence with approximately 90
  mortality rate.

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• Current Protective Lung Strategies
• Lower VTs with ALI/ARDS patients about 6 ml/Kg
  IBW to avoid volutrauma from alveolar over
  distension
• Sufficient PEEP to prevent alveolar collap