FLOW-i Modes of Ventilation Pocket Guide Rev A Aug 2012

EMPTY Table of contents 1 2 3 4 5 6 7

Introduction | Important ventilatory settings | Volume Control (VC) | Pressure Control (PC) | Pressure Regulated Volume Control (PRVC) | Pressure Support (PS) | Synchronized Intermittent Mandatory Ventilation (SIMV) |

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INTRODUCTION Introduction

The FLOW-i anesthesia system offers a number of ventilation modes which clinicians can tailor to their patients' needs. The aim of this pocket guide is to provide information about these modes, and to present some of the most important ventilatory settings. It is however important to remember that it only covers selected topics and cannot replace the user’s manual and the service manual. For detailed information, always refer to these manuals. Details about the modes of ventilation, for example, can be found in the relevant FLOW-i user's manual.

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INTRODUCTION Summary of FLOW-i's mechanical ventilation modes Controlled modes

Supported modes

Combined modes

VC PC PRVC

PS

SIMV: VC + PS PC + PS

In addition, it is also possible to ventilate patients manually by using the manual ventilation system (MAN), or in case of emergency by using the emergency ventilation system (see below). An option on the FLOW-i is the Additional Fresh Gas Outlet (AFGO), which allows connection of breathing systems such as a Jackson-Rees, Bain or Mapleson system.

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INTRODUCTION Examples of flow patterns in mechanical ventilation Flow pattern in Volume Control (VC)

Pressure

The flow is constant during inspiration in Volume Control and SIMV (VC). During the pause time the flow is zero. At the beginning of expiration, flow is large. It gets smaller and smaller and reaches zero by the end of expiration.

P

Peak pressure Plateau pressure

Presistance Pcompliance

End expiratory pressure

time (s) V

Flow

End inspiratory flow

Inspiratory volume End expiratory flow

Expiratory volume

time (s)

Volume

V

time (s) Inspiration phase

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Expiration phase

INTRODUCTION Flow pattern in Pressure Control (PC)

Pressure

In Pressure Control, Pressure Regulated Volume Control (PRVC), Pressure Support, and SIMV (PC) with Pressure Support, the flow is decelerating and the pressure is constant. P

Peak pressure

time (s)

Flow

V

End inspiratory flow

Volume

End expiratory flow

Inspiratory volume

time (s) Expiratory volume

V

time (s) Inspiration phase

Expiration phase

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INTRODUCTION Ventilating patients with FLOW-i In addition to the mechanical ventilation modes listed above, the user may also choose to ventilate a patient manually.

The MAN/AUTO switch

The MAN/AUTO switch sets the status of the FLOW-i to either manual (MAN) or automatic (AUTO) ventilation. When the switch is set to MAN, the manual ventilation valve opens and the manual ventilation bag is connected to the breathing system. This setting will also enable APL regulation via the APL (Adjustable Pressure Limit) valve. Some machines also have an optional Additional Fresh Gas Outlet (AFGO) that allows connection of special breathing circuits. Manual ventilation is described under the next subheading.

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INTRODUCTION When the switch is set to AUTO, the manual ventilation valve closes and the manual ventilation bag is disconnected from the breathing system. The APL valve is then also disabled. The screen shot below shows how to select a mechanical ventilation mode after turning the MAN/AUTO switch to AUTO.

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INTRODUCTION The next two screen shots below illustrate the settings for Volume Control, together with an example showing this mode activated and running on the FLOW-i.

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INTRODUCTION Manual ventilation

Select the correct breathing bag and tube depending on the patient category. The pressure limit is set with the help of the APL valve. The pressure can be set anywhere between a value corresponding to a fully open valve (for spontaneous breathing) and 80 cmH2O.

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INTRODUCTION At values above 30 cmH2O, an increased tactile resistance can be felt and a slight click can be heard at every 5 cmH2O interval. The set pressure limit (APL) is displayed at the bottom left of the screen.

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INTRODUCTION Emergency ventilation

The FLOW-i anesthesia system's emergency ventilation includes: the emergency ventilation on/off switch the O2 gas supply knob and flowmeter the emergency APL valve regulator clear and simple instruction for accessing this function In case of a total power (mains power and battery) or system failure, the patient can be manually ventilated using the emergency ventilation system. The system is activated by turning on the activation switch and adjusting the oxygen flow, which can be set to up to 10 l/min. The pressure level is adjusted by the mechanical APL regulator. The patient is ventilated with the help of the manual ventilation bag. If the emergency ventilation system is activated while the anesthesia system is in operation, the anesthesia system will be shut down.

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IMPORTANT VENTILATORY SETTINGS Important ventilatory settings PEEP Positive End Expiratory Pressure (PEEP) can be set in the range of 0 - 50 cmH2O. A positive end expiratory pressure is maintained in the airways and may prevent collapse of the alveoli.

P cm H2O

5 PEEP 0 time

Auto PEEP If the respiratory rate is set high or the expiratory time is not long enough there is a risk for auto PEEP. The patient does not have enough time to exhale and it is evident on the flow curve that flow will not return to zero before the next breath starts.

. V

time

There are different ways to check on the FLOW-i whether the patient has an auto PEEP. The expiratory flow will not go back to zero before the next inspiration starts, as shown on the curve above. The measured value

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ee is not zero.

IMPORTANT VENTILATORY SETTINGS Inspiratory rise time Inspiratory rise time is the time taken to reach peak inspiratory flow or pressure at the start of each breath, expressed either as a percentage of the respiratory cycle time or in seconds. The flow and pressure rise time can be adapted to suit the patient. The inspiratory rise time has to be set to a comfortable value for the patient and can be evaluated by the shape of the flow and pressure curves.

Insp rise time P

0

time 100%

V

0 time

Note: The inspiratory rise time is shown in seconds (0-0.4 s) if: the FLOW-i is configured to show inspiratory time in seconds the patient is being ventilated in Pressure Support mode The inspiratory rise time is shown as a percentage (0-20%): in all controlled modes of ventilation if the FLOW-i is configured for the I:E ratio

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IMPORTANT VENTILATORY SETTINGS

Inspiratory cycle off Inspiratory cycle off is the point at which inspiration changes to expiration in Pressure Support.

Important: Set the inspiratory cycle off correctly to avoid hyperinflation of the lungs and increased work of breathing. It is possible to set the inspiratory cycle off from 1% to 80% of inspiratory peak flow for both adults and infants (default values are 50% for adults and 50% for infants). If the inspiratory cycle off cuts off inspiration too early, the patient will not get enough tidal volume. If the pressure increases 3 cmH2O above the set Pressure Support level above PEEP, ventilation switches from inspiration to expiration.

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IMPORTANT VENTILATORY SETTINGS Trigger sensitivity Trigger sensitivity determines the level of patient effort needed to trigger the FLOW-i to deliver an inspiration. Trigger sensitivity can be set as either flow triggering or pressure triggering. Important: The trigger level should be set as sensitively as possible without causing autotriggering. During expiration, the FLOW-i continuously delivers a fresh gas flow of 2 l/min (approx. 33 ml/s) for adults and 0.5 l/min (approx. 8.25 ml/s) for infants. When the difference between the inspiratory and expiratory flows reaches the preset flow trigger level, the FLOW-i will start to deliver a new inspiration. V Exp

< 2l/min (adult) < 0.5 l/min (infant)

V Insp

2l/min (adult) 0.5 l/min (infant)

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IMPORTANT VENTILATORY SETTINGS Examples of flow and pressure triggering The flow trigger sensitivity setting is divided into steps of 10%, with each step increasing the trigger sensitivity. In the red area the patient only has to inhale a very small part of the trigger flow to trigger a breath and there is therefore a risk for autotriggering.

TRIGG. FLOW -20

-20

-2 0

0

TRIGG. FLOW -20

TRIGG. PRESSURE

1

7 0

The pressure trigger sensitivity can be set within the range 0-(-20) cmH2O. To initiate a breath the patient has to create the negative pressure that is set as trigger sensitivity. The higher the negative trigger pressure set on the FLOW-i, the more work of breathing the patient must perform. The trigger level should be set as sensitively as possible without causing self-triggering – autotriggering.

If an external gas analyzer is connected to the system, the trigger sensitivity may need adjusting to avoid autotriggering. 18 1.8

IMPORTANT VENTILATORY SETTINGS

When the patient triggers a breath, "Triggering" appears above the pressure curve or flow curve in the waveform display area. A section of the pressure or flow curve also changes color to indicate that the patient is triggering the breath. Notes: 1. If the breath is flow-triggered, then the color change is seen on the flow curve. 2.

If the breath is pressure-triggered, then the color change is seen on the pressure curve.

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VOLUME CONTROL (VC) Volume Control (VC)

In this controlled mode of ventilation the FLOW-i delivers the preset tidal volume with a constant flow during the preset inspiratory time with the preset pause time and at the preset respiratory rate. The peak pressure can vary from breath to breath if the patient's compliance and/or resistance change. In a system with no leakage, the inspired tidal volume should be the same as the expired tidal volume. The time for inspiration and expiration can be configured so that it is set either as the I:E ratio or as inspiration time in seconds.

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VOLUME CONTROL (VC) When using the FLOW-i anesthesia system, you can choose whether you want to set the tidal volume (as in the screen shot above) or the minute volume. The flow during Volume Control ventilation is constant. The inspiratory rise time in % is seen in the information area in the "Set ventilation mode" menu. Inspiratory rise time: time to peak inspiratory flow at the start of each breath as a percentage of the respiratory cycle time. It is very important to set a sensitive triggering level so as to allow the patient to breathe spontaneously as soon as possible. If the patient is making an inspiratory effort during the expiratory phase, an assisted breath is delivered with the same tidal volume as set on the ventilator. Immediate sensing of inspiratory effort by the patient is crucial to synchrony between patient and machine.

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