PRVC mode of ventilation

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PRVC(PRESSURE REGULATED VOLUME CONTROL
VENTILATION)
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How PRVC works

• PRVC is a form of an adaptive pressure controlled
  ventilation in which tidal volume is used as a
  feed back control to continuously adjust the
  pressure limit.
• This adaptive mode of ventilation targets the
  lowest inspiratory pressures to achieve the set
  tidal volume.
• Adaptive targeting system in PRVC is a great
  asset in our ventilator toolbox. In most cases,
  PRVC can deliver the desired tidal volume at the
  lowest pressures, using the Adaptive targeting
  scheme as a feedback method.

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How PRVC works

• Assist-control ventilation ventilator initiated
  (control breath) patient initiated (assist
  breath)
• Pressure limit is set within that set pressure
  limit tidal volume is delivered.
• ventilator adjusts pressure from breath to
  breath, as patient's airway resistance and
  respiratory system compliance changes, in order
  to deliver the set tidal volume
• ventilator monitors each breath and compares the
  delivered tidal volume with the set tidal volume.
  If the delivered volume is too low it increases
  the inspiratory pressure on the next breath. If
  it is too high it decreases the pressure

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How PRVC Works
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How Works

• The maximum allowed inspiratory pressure is 5 cm
  H2O below the upper pressure alarm limit
• The duration of inspiration is determined by the
  respiratory rate and the IE ratio or inspiratory
  time (ie this is a time-cycled mode of
  ventilation)

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Set Tidal Volume Varying Pressure during delivery
of TV
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Settings

• Respiratory Rate
• Pts spontaneous RR lt set rate machine
  gives additional control breaths
• to make up difference ,pts spontaneous
• rate gt
• set rate no control breaths

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Target tidal volume

• Initial setting 6-8 ml/kg Ideal body weight
  based on height

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PRESSURE
Ventilator delivers pressure of up to 5 cm H2O
below upper pressure alarm limit set to 35-40 cm
H2O to ensure "safe" pressures do not exceed
this setting without consulting an ICU specialist
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FIO2

• Initially 100 except in case of some disease
  where oxygen is contraindicated.FIO2 can be
  tapered off according to Po2

IE ratio

• Initial setting 12 (inspiratory time of 33)
  ,consider longer inspiratory time if there is no
  intrinsic PEEP, no bronchospasm and oxygenation
  is poor

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PEEP

• initial setting 5-10 cm H2O

• Trigger Sensitivity

• According to Situation

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Introduction to various modes of mechanical
ventilation
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Pressure - Volume Curve
Increased Compliance
Increased Resistance
Overdistension
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Pressure - Time Curve
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Table 1 Physiological variables during the two
modes of mechanical ventilation,
pressure-regulated pressure control (PRVC) and
volume control (VC) PRVC (n 44) VC (n
44) P PIP (cmH2O) 20 (19-23) 24 (23-27) lt
0.0001 MAIP (cmH2O) 10 (9-11) 10 (9-11) ns PaO2
(mmHg) 98 (93-111) 96 (92-108) ns PaCO2 (mmHg) 43
(40-46) 43 (40-46) ns pH 7.38 (7.11-7.65) 7.38
(7.10-7.65) ns MAP (mmHg) 76 (73-83) 77
(74-84) ns Values are means (95 confidence
limits). PIP peak inspiratory pressure MAIP
mean airway pressure PaO2 partial pressure of
arterial oxygen PaCO2 partial pressure of
arterial carbon oxide MAP me
US National Library of Medicine National
Institutes of Health
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Table 2 Results of the general trial
PRVC (n 22) VC (n
22) P Days on ventilator 7.0 (3.8-10.3) 6.2
(3.8-8.5) ns Failing 0/22
2/22
ns Survival 12/22 11/22
ns Days on ventilator median
(95 confidence limits) number of days spent on
mechanical ventilation Failing number of
patients failing the assigned mode of
ventilation Survival survival in the two
groups.
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Advantages

• Decelerating inspiratory flow pattern with
  automatic adjustment of the inspiratory pressure
  for changes in compliance and resistance
  resulting in a guaranteed tidal volume

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References 1 R.L. Chatburn, E. Mireles-Cabodevil
aClosed-loop control of mechanical ventilation
description and classification of targeting
schemes Respir. Care, 56 (1) (2011),
pp. 85-102 CrossRefGoogle Scholar 2 R.D. Branson
, R.L. ChatburnControversies in the critical care
setting. Should adaptive pressure control modes
be utilized for virtually all patients receiving
mechanical ventilation? Respir.
Care, 52 (4) (2007), pp. 478-485 discussion
485-478 View Record in ScopusGoogle
Scholar 3 H. Guldager, S.L. Nielsen, P. Carl, M.
B. SoerensenA comparison of volume control and
pressure-regulated volume control ventilation in
acute respiratory failure Crit. Care (Lond.
Engl.), 1 (2) (1997), pp. 75-77 View Record in
ScopusGoogle Scholar 4 S. Jaber, J.M. Delay, S. 
Matecki, M. Sebbane, J.J. Eledjam,  L. BrochardVol
ume-guaranteed pressure-support ventilation
facing acute changes in ventilatory
demand Intensive Care Med., 31 (9) (2005),
pp. 1181-1188 pp. 1623-1631
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• Slustsky AS. ACCP consensus conference
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