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میترا حکمت افشار

دانشجوی ترم دوم کارشناسی ارشد مراقبت های ویژه

پرستاری

1389اردیبهشت

Email :m.hekmatafshar@yahoo.com

جناب آقای رحمانی استاد راهنما:

Ventilator settings

Modes of ventilation

Monitoring of the patient

Trouble shooting

•Negative-pressure ventilators (“iron lungs”)

•Non-invasive ventilation first used in Boston Children’s Hospital in 1928

•Used extensively during polio outbreaks in 1940s – 1950s

•Positive-pressure ventilators

• Invasive ventilation first used at Massachusetts General Hospital in 1955

•Now the modern standard of mechanical ventilation

VENTILATOR VENTILATOR SETTINGSSETTINGS

Ventilator mode Respiratory rate Tidal volume or pressure

settings Inspiratory flow I:E ratio PEEP FiO2 Inspiratory trigger

• What is the pt actual rate demand?

Set as:% of respiratory cycle RR:10 I:E =1/2 Total respiratory

time=60/10 TCT=6 SecI:E ratio

Expiratory time not setRemaining time after inspiration

before next breath

Maximum volume/pressure to achieve good ventilation and oxygenation without producing alveolar overdistention

Max cc/kg? = 10 cc/kg

Some clinical exceptions

Varies with the Vt, I:E and RR

Normally about 35-45 l/min

1:2

Prolonged at 1:3, 1:4, …

Inverse ratio

The usual goal is to use the minimum Fio2 required to have a PaO2 > 60mmhg or a sat >90%

Start at 100%

Oxygen toxicity normally with Fio2 >40%

2 modes:

Airway pressureFlow triggering

What is PEEP?

What is the goal of PEEP?

Improve oxygenation

Diminish the work of breathing

BarotraumaDiminish cardiac output

Regional hypoperfusionNaCl retentionAugmentation of I.C.P.?Paradoxal hypoxemia

Contraindication:No absolute CI

BarotraumaAirway traumaHemodynamic instabilityI.C.P.?Bronchospasm?

WHAT PEEP DO YOU WANT?

Usually, 5-10 cmH2O

determines speed of rise of flow (volume control mode) or pressure (pressure control and pressure regulated volume control modes)

very short rise times may be more uncomfortable for the patient

long rise times may result in a lower tidal volume being delivered (pressure control mode) or higher pressure being required (volume control and pressure regulated volume control modes)

•Ventilation vs. Oxygenation

•Pressure Cycling vs. Volume Cycling

The goal of ventilation is to facilitate CO2 release and maintain normal PaCO2

•Minute ventilation

(MV)

•Total amount of gas

exhaled/min.

•VE = (RR) x (TV)

•VE comprised of 2

factorsV/Q Matching. Zone 1 demonstrates dead-space ventilation (ventilation without perfusion). Zone 2 demonstrates normal perfusion. Zone 3 demonstrates shunting (perfusion without ventilation).

The primary goal of oxygenation is to maximize O2 delivery to blood (PaO2)

•Alveolar-arterial O2 gradient (PAO2 – PaO2)

•Oxygenation in context of ICU

•V/Q mismatching• Patient position (supine)• Airway pressure, pulmonary

parenchymal disease, small-airway disease

•Adjustments: FiO2 and PEEP

V/Q Matching. Zone 1

demonstrates dead-space

ventilation (ventilation without

perfusion). Zone 2 demonstrates

normal perfusion. Zone 3

demonstrates shunting (perfusion

without ventilation).

Pressure-cycled modes deliver a fixed

pressure at variable volume (neonates)

Volume-cycled modes deliver a fixed

volume at variable pressure (adults)

•Pressure-cycled modes• Pressure Support Ventilation (PSV)• Pressure Control Ventilation (PCV)• CPAP• BiPAP

•Volume-cycled modes• Control• Assist• Assist/Control• Intermittent Mandatory Ventilation (IMV)• Synchronous Intermittent Mandatory Ventilation (SIMV)

Volume-cycled modes have the inherent risk of volutrauma.

Patient determines RR, VE, inspiratory time – a purely spontaneous mode

•Parameters• Triggered by pt’s own

breath• Limited by pressure• Affects inspiration only

•Uses• Complement volume-cycled

modes (i.e., SIMV)

• PSV alone• Used alone for recovering

intubated pts who are not quite ready for extubation

• Augments inflation volumes during spontaneous breaths

• BiPAP (CPAP plus PS)

PSV is most often used together with other volume-cycled modes. PSV provides sufficient pressure to overcome the resistance of the ventilator tubing, and acts during inspiration only.

Ventilator determines inspiratory time – no patient participation

•Parameters•Triggered by time•Limited by pressure•Affects inspiration only

•Disadvantages•Requires frequent adjustments to maintain adequate VE

•Pt with noncompliant lungs may require alterations in inspiratory times to achieve adequate TV

CPAP is essentially constant PEEP; BiPAP is CPAP plus PS

•Parameters CPAP – PEEP set at 5-10 cm H2O BiPAP – CPAP with Pressure Support (5-20 cm

H2O) Shown to reduce need for intubation and

mortality in COPD pts

Indications When medical therapy fails (tachypnea,

hypoxemia, respiratory acidosis) Use in conjunction with bronchodilators,

steroids, oral/parenteral steroids, antibiotics to prevent/delay intubation

Weaning protocols Obstructive Sleep Apnea

•Control Mode•Pt receives a set number of

breaths and cannot breathe between ventilator breaths

•Similar to Pressure Control

•Assist Mode•Pt initiates all breaths, but

ventilator cycles in at initiation to give a preset tidal volume

•Pt controls rate but always receives a full machine breath

•Assist/Control Mode•Assist mode unless pt’s

respiratory rate falls below preset value

•Ventilator then switches to control mode

•Rapidly breathing pts can overventilate and induce severe respiratory alkalosis and hyperinflation (auto-PEEP)

Ventilator delivers a fixed volume

•IMV•Pt receives a set number of

ventilator breaths

•Different from Control: pt can initiate own (spontaneous) breaths

•Different from Assist: spontaneous breaths are not supported by machine with fixed TV

•Ventilator always delivers breath, even if pt exhaling

•SIMV•Most commonly used mode

•Spontaneous breaths and mandatory breaths

• If pt has respiratory drive, the mandatory breaths are synchronized with the pt’s inspiratory effort

      

FIGURE 7-10 Synchronized intermittent mandatory ventilation (SIMV) with pressure support (PS) ventilation. In SIMV and PS, mandatory breaths of a preset tidal volume are administered in the fashion of SIMV. In this figure the square waveform is applied to the mandatory breaths. Only spontaneous breaths are pressure supported ,and not the mandatory breaths.

•PEEP • Increases FRC

• Prevents progressive atelectasis and intrapulmonary shunting

• Prevents repetitive opening/closing (injury)

•Recruits collapsed alveoli and improves V/Q matching

• Resolves intrapulmonary shunting

• Improves compliance

•Enables maintenance of adequate PaO2 at a safe FiO2 level

•Disadvantages• Increases intrathoracic pressure.

• May lead to ARDS.

• Rupture: PTX, pulmonary edema.Oxygen delivery (DO2), not PaO2, should be used to assess optimal PEEP.

•Respiratory rate•Max RR at 35 breaths/min

•Efficiency of ventilation decreases with increasing RR

•Decreased time for alveolar emptying

•TV

•Goal of 10 ml/kg

•Risk of volutrauma

RR and TV are adjusted to maintain VE and PaCO2

•I:E ratio• Increasing inspiration time

will increase TV, but may lead to auto-PEEP

•PIP•Elevated PIP suggests need

for switch from volume-cycled to pressure-cycled mode

•Maintained at <45cm H2O to minimize barotrauma

•Plateau pressures•Pressure measured at the

end of inspiratory phase•Maintained at <30-35cm

H2O to minimize barotrauma

Spontaneous inspiratory efforts

trigger the ventilator to provide

a variable flow of gas in order to

attain a preset airway pressure.

Can be used in adjunct with

SIMV.

MONITORING OF THE PATIENT

Time

Pre

ssu

re

Time

Pre

ssu

re

which pressure is going up

Ppeak is up

Look at your Pplat

If your Pplat is high, you are faced with a COMPLIANCE problem

If your Pplat is N, you are faced with a RESISTIVE problem

Remove pt from ventilator

Initiate manual ventilation

Perform P/E and assess monitoring indices

Check patency of airway

Type of patient Tidal Volume RR PEEP FIO2 Ins. Flow I:E Note Note

Normal 10 cc/kg 10 to 12 0 to 5 100%. 35-45 1:2.

ARDS 6 cc/kg 10 to 12 5 to 15 100%. 35-45 1:2. 2:1 3:1

COPD 6 cc/kg 10 to 12 5 to 10 100%. ↑normal 1:3 to 1:4 PH>7.2PCO2 <80 mmhgTrigger to consider

Trauma 10 cc/kg 10 to 12 0. 100%. 35-45 1:2.

Pediatric 8-10 cc/kg Varies age 3 to 5 100%. 35-45 1:2. Trigger to consider

Ventilator settings

Monitoring of the patient

Trouble shooting

REFERENCE Critical care nursing patricia gonce morton 2009. Aaccn essential of critical care nursing marian chaly 2006. The icu book marino 2007. Critical care nursing jaya 2007.

کاربردهای فیزیولوزیکی و کلینیکی تنفس مکانیکی:دکتر شمس زاده امیری1375.

. 1379 تنفس مکانیکی در بخشهای مراقبت ویژه –دکتر مسعود صابری مراقبت های پرستاری در بخشicu,ccu , 1381دیالیز معصومه ذاکری 1377مراقبت پرستاری در ای سی یو مالحت نیکروان-حسین شیری. مراقبت پرستاری ویژهICU,CCU, دیالیز-شیوا بستام پور-احمد اسدی

1384نوقابی

Chronic Obstructive Pulmonary Disease and Weaning of Difficult-to-wean Patients from Mechanical Ventilation: Randomized Prospective Study .Croat Med J 2007;48:51-58

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