niv updated

Non-invasive ventilationUpdated.

Dr Mohammed AL-Shamsi.R5

Outlines

Definition of NIV.Brief Historical review.Mechanism of action Indications & contraindications. CPAP versus BiPAP. NIV and the evidence. Conclusion.

NIV: Definition

• Non-invasive ventilation (NIV) is provision of ventilatory assistance without the need for airway invasion, has seen increasing use in critical care units to avoid endotracheal intubation and its attendant complications

Historical review

Calif Med. 1951 July

USE OF THE ROCKING BED TO AUGMENT VENTILATION IN PATIENTS WITH POLIOMYELITIS

• The rocking bed will give artificial respiration in cases of respiratory weakness, but will not provide enough tidal air for the patient with paralysis of the muscles of respiration.

Pressure ventilation vs. volume Pressure ventilation vs. volume ventilationventilationPressure-cycled modes deliver a fixed pressure at variable volume (neonates)

Volume-cycled modes deliver a fixed volume at variable pressure (adults)

•Pressure-cycled modes(P fixed, Vt variable)

•Pressure Support Ventilation (PSV)•Pressure Control Ventilation (PCV)•CPAP•BiPAP

•Volume-cycled modes (Vt fixed, P variable)

•Control•Assist•Assist/Control• Intermittent Mandatory Ventilation

(IMV)•Synchronous Intermittent Mandatory

Ventilation (SIMV)

Peak- end expiratory pressure(PEEP)

Contraindications Respiratory arrest Airway obstruction Facial trauma or burn. Severe acidosis pH <7.2. Hypotension , SBP< 90 mmHg. Uncontrolled arrhythmias, AMI Inability to cooperate( severe agitation, impaired

mental status) Excessive airway secretion and vomiting Recent upper airway of GI surgerypneumothorax

Patients selection

17

Modes of NIPPV

• 3 modes

1- continuous positive airway pressure ventilation (CPAP)

2- Bilevel positive airway pressure ventilation (S/T)

3- Proportional Assist Ventilation (PAV): (optional mode)

CPAP Improve oxygenation by increasing

FRC and recruiting collapsed alveoli

It provides certain positive airway pressure throughout all phases of spontaneous ventilation

It is similar to breathing with your head stuck out of a moving car

CPAP PEEP

CPAP reduces preload and afterload. Hence it is a very effective for treatment of pulmonary oedema.

Pressures are usually limited to 5-12 cm of H2O, since higher pressure tends to result in gastric distension requiring continual aspiration through a nasogastric tube.

Pressure Waveform CPAP

0

BiPAP

• IPAP + EPAP( CPAP)• The higher pressure augments alveolar

ventilation and CO2 clearance• The lower pressure maintains alveolar

recruitment

- IPAP: assists in improving tidal volume, thus decreasing CO2

- EPAP : improve FRC, helps recruit more alveoli, thus increasing O2. may reduce work of

breathing associated

with autopeep

20

10

0

IPAP = 12

EPAP = 4

PS = 8

BiPAP

NIV - Changes in EPAP Pressure

5 cm

Delta P 10 cm

10 cm

15 cm

Delta pressure 5 cm

EPAP increased to 10 cm

IPAP increased to 20 cm

Delta P returned to 10 cm

PRESSURE

Decreasing delta pressure will usually result in lower Vt

• Differential in pressure between inspiration and expiration allows for better patient-ventilator synchrony and thus more comfort

• EPAP CPAP PEEP• IPAP PS

– Augments TV – Reduces Atelectasis– Reduces WOB

PAV

• New Assist Mode of Ventilation– Fundamentally different concept

• Ventilator Generates Pressure in Proportion to Patient Effort– Follows and adjusts to patient changes

PatientEffort

Pressure

PSV PAV

From Pressure Support to PAV

Non-invasive PAV for Acute Respiratory Insufficiency

• Peter Gay and coll, Am J Respir Crit Care• General ICU

• COPD patients with acute exacerbation

• 44 patients were randomized to receive NPPV with PAV or Pressure Support (PS)

Mortality and intubation rate were similar but refusal rate was Mortality and intubation rate were similar but refusal rate was lower with PAVlower with PAV

Reduction in respiratory rate was more rapid with PAV and Reduction in respiratory rate was more rapid with PAV and there were fewer complications in the PAV groupthere were fewer complications in the PAV group

28

• Plug into AC mains & Connect to 50 psi gas source

• Connect BiPAP circuit - don’t cap• Power switch RU corner on back panel – ON

Initial ventilator settings and adjustments

Dispos-able inlet filter

Fuses

O2

module

29

30

Power-on-self-test (POST) initiates

31

After POST, Start “Test Exhalation Port”

32

Follow steps on screen, block circuit, “Start Test”.

Exhalation (castle) port

33

Exhalation port test in progress

34

Test Complete, press Monitoring to exit.

Monitoring

35

Monitoring

Parameters

Mode

Alarms

Alarm Silence

Alarm Reset

21%

options

SB

IPAP 8

EPAP 3

Rate 12

Pt DataDisplayArea

Scale Fz/UnFz

Mode/MessagesALARMS

36

To change Mode, press Mode, then parameter soft key to adjust, and then

“Activate New Mode” soft key

1

2

3

37

To change settings, press Parameters – then soft key next to parameter and

adjust with knob.

Soft keysSoft keys

KnobKnob

Ranges

• CPAP range 4- 20 cmH2O • O2 % range: Change 4% from 21- 25%, 5%

from 25- 100% • IPAP 4-40 cmH2O • EPAP 4 -20 cmH2O • Rate 4-40 can’t exceed 1:1 ratio • Inspiratory Time 0.5- 3 seconds • Rise Time 0.05- 0.4 seconds (0.05, 0.1, 0.2, &

0.4 sec)

Initial IPAP/EPAP settingsStart at 10 cm water/5 cm waterPressures less than 8 cm water/4 cm water not advised as this may be inadequateInitial adjustments to achieve tidal volume of 5-7 mL/kg (IPAP and/or EPAP)

Subsequent adjustments based on arterial blood gas values Increase IPAP by 2 cm water if persistent hypercapniaIncrease IPAP and EPAP by 2 cm water if persistent hypoxemiaMaximal IPAP limited to 20-25 cm water (avoids gastric distension, improves patient comfort)Maximal EPAP limited to 10-15 cm waterFIO2 at 1.0 and adjust to lowest level with an acceptable pulse oximetry valueBack up respiratory rate 12-16 breaths/minute

Hospital NPPV Protocol1- Identify candidates for NPPV

2- Choose appropriate mask , keep bed up at 45 degree, explain to the patient what you are doing and what to expect

3- Turn on he NPPV and choose the appropriate mode according to diagnosis

4- Adjust the NPPV:Initial setting: S/T mode:IPAP =10 (pressures above 20 cm H2O are usually not well tolerated)

EPAP=4 ( the more hypoxic the patient, the higher the initial EPAP setting may need to be)

Backup rate: 10-12 bpm

FiO2 : start low and adjust based upon SaO2( minimum FiO2 to keep SpO2> 90%).

Timed Inspiration: for a timed breath only (mechanical breath)

CPAP: For patients with cardiogenic pulmonary oedema without hypercapnia, CPAP 8 – 15 cm water via face mask can be tried. The FiO2 can be adjusted according to the arterial blood gases and SpO2

5- Apply the mask– Without ventilator hose attached– Elicit patient help if possible to hold the mask– Allow two fingers to be easily inserted between the mask and the

patient's face– Do not fit the mask too tight– Apply ventilator hose to mask

6- Change the setting to Optimize synchrony, Optimize Vt and /or PCO2, spo2, minimize accessory muscle use , Alleviate dyspnea and decrease RR.

• Adjust IPAP by incements of 2 cm H2O q 5 mits optimize Vt , decrease PCO2 and relieve respiratoy distress symptoms

• Adjust EPAP in incements of 2cm H2O to increase SpO2. (Note: When increasing EPAP, increase IPAP by same amount to maintain same level of Pressure Support)

• Adjust Rise Time (Rise Time determines how fast the ventilator rises from the baseline/EPAP to the target pressure/IPAP ) to achieve pt comfort and patient/ventilator synchrony

7- Set alarms to appropriate levels

8-Monitor patients:• ABGs , SpO2 • Respiratoy symptoms Improvement shold be seen withi ½ h

• Pt tolerance and comfort

9-help pt accept therapy

• Involve patients

• Be supportive( support the pt until he/she feels comfortable with the therapy)

• Be encouraging

• Be attentive

First hour……..

• Titrate settings and FiO2

• Close monitoring ( WOB /RR, pt comfort and tolerance, mental status)

• Monitor blood gases initially q 30 min to 1 hour then prn

• Minimal sedation may be usedMorphine 2 mg

• Intubate if worsening

Initial Assessment• Items reflecting increased success

- younger age- good dentition , less air leak- normal mental status , less secretion- adequate cooperation , - ability to achieve synchrony with the ventilator- lower acuity of illness

- PH >7.1 , pco2 < 92- improvement in clinical and laboratory parameters within 1-2 hours of treatment initiation ( PH , Pco2 , RR)

Discontinuation of Therapy

• Indictors of NIV failure- patient intolerance for NIV- deterioration of vital sign- failure to improve after 1-2 hours in NIV- progressive confusion or sedation- inability to handle secretions- chest pain- arrhythmia- apnea

NIPPV and EBM

• Evidence has been rapidly accumulating to support many applications of NIV in the acute setting

NIPPV in COPD

Meta-analysis of fourteen RCT • Decreased mortality (Relative Risk 0.52; 95%CI 0.35 to 0.76) • Decreased need for intubation (RR 0.41; 95%CI 0.33 to 0.53) • Reduction in treatment failure (RR 0.48; 95%CI 0.37 to 0.63)• Less complications associated with treatment (RR 0.38;

95%CI 0.24 to 0.60) • Shorter hospital stay ( -3.24 days; 95%CI -4.42 to -2.06)

• “Data from good quality randomised controlled trials show benefit of NPPV as first line intervention as an adjunct therapy to usual medical care in all suitable patients for the management of respiratory failure secondary to an acute exacerbation of COPD.”

Cochrane Database Syst Rev. 2004

NIPPV &COPD

• Noninvasive ventilation is most effective in patients with moderate-to-severe disease

• Hypercapnic respiratory acidosis may define the best responders (pH 7.20-7.30).   – Noninvasive ventilation is also effective in patients

with a pH of 7.35-7.30, but no added benefit is appreciated if the pH is greater than 7.35.

– The lowest threshold of effectiveness is unknown, but success has been achieved with pH values as low as 7.10.

Respir Care. 2005 May• NIV in pts with milder COPD exacerbations: RCT.• Patients with mild COPD + pH of >7.30 were eligible .• MEASUREMENTS: Borg dyspnea index at baseline, 1

hour, and daily, Length of hospital stay, endotracheal intubation, hospital survival

• RESULTS : NPPV was poorly tolerated, sig. decrease in dyspnea at 1 hour and 2 days, No differences were seen for any measured variable.

• CONCLUSIONS: The effectiveness and cost-effectiveness of the addition of NPPV to standard therapy in milder COPD exacerbations remains unclear.

NIPPV & Cardiogenic pulmonary edema

• There are clear benefits in meta-analysis of randomized trials for CPAP– risk of mortality 0.59

• 95%CI 0.38-0.90– risk of intubation 0.44

• 95%CI 0.29-0.66

Peter JV, Moran JL, Phillips-Hughes J, Graham P, Bersten AD. Effect of non-invasive positive pressure ventilation (NIPPV) on mortality in patients with acute cardiogenic pulmonary oedema: a meta-analysis. Lancet 2006; 367: 1155–1163.

Rasanen 1985

Finland

40 patients CPAP (20)

V Control (20)

Intubation

Mortality

6/20 v 12/20 17/20 v 14/20

NS

NS

Bersten 1991

Australia

39 patients CPAP (19)

V Control (20)

Intubation

Mortality

0/19 v 7/20

2/19 v 4/20

<0.005

NS

Lin 1991

Taiwan

55 patients CPAP (25)

V Control (30)

Intubation

Mortality

7/25 v 17/30

2/25 v 4/30

<0.05

NS

Lin 1995

Taiwan

100 patients CPAP (50)

V Control (50)

Intubation

Mortality

8/50 v 18/50

4/50 v 6/50

<0.01

NS

Takeda 1998 Japan

22 patients CPAP (11)

V Control (11)

Intubation

Mortality

2/11 v 8/11

1/11 v 7/11

<0.03

0.02

• In CPAP group all studies showed a significant improvement in :

Respiratory status

Cardiovascular parameters

Blood gas analysis

• No reported complications in any study

CPAP or BiPAP ?

• BiPAP group : improvement in PaC02, pH, HR, RR

(p <0.05)

• CPAP group : improvement in RR only (p <0.05)

Mehta 1997 USA

27 patients BiPAP (14)

V CPAP (13)

Intubation

Mortality

MI

1/14 v 1/13

1/14 v 2/13

10/14 v 4/13

NS

NS

0.05

CPAP VS BIPAP

Risk ratio of acute myocardial infarction

Annals of Emergency Medicine 2007

• prospective multicenter RCT , 3 emergency departments

• The main outcome was a combined criterion (tracheal intubation, death, or MI )

• 109 patients were analyzed, 59 in the CPAP arm and 50 in the BiPAP arm.

Results• After 1 hour of ventilation and at the end of the

ventilation period, clinical parameters of respiratory distress and blood gas exchange significantly improved in each treatment arm.

• No significant differences were observed between the CPAP and BiPAP arms for the combined criterion and also for severe complications, duration of ventilation duration of hospitalization .

• Similar results were obtained among hypercapnic patients (PaCO2 >45 mm Hg).

• Whatever the ventilation support used, the combined criterion and severe complications were more frequently observed among hypercapnic patients.

Conclusion

• Both CPAP and BiPAP appeared effective in rapidly improving respiratory distress even in hypercapnic patients, but they were not different in terms of patient outcome.

Efficacy and safety of non-invasive ventilation in the treatment of acute cardiogenic pulmonary

edema – meta-analysis: critical care, 2006 17 articles were reviewed. In a pooled analysis, 10 studies of CPAP compared to

standard medical therapy (SMT) showed a significant 22% absolute risk reduction (ARR) in NETI and 13% in mortality .

Seven studies of BiPAP compared to CPAP showed a non-significant 3% ARR in NETI (95%CI, -4% to 9%) and 2% in mortality (95%CI, -6% to 10%). None of these methods increased AMI risk. In a subgroup analysis, BiPAP did not lead to better outcomes than CPAP in studies including more hypercapnic patients.

Ann Emerg Med 2006

• Collins et al.

• Meta-analysis of 494 patients and the use of NIV in the ED for acute CPE

• Results : NIV significantly reduced hospital mortality (relative risk [RR] 0.61, 95% confidence interval [CI] 0.41–0.91).

N Engl J Med 2008; 359:142-151July 10, 2008

• Prospective, randomized, controlled trial, 26 EDs in UK.• Patients were assigned to standard oxygen therapy,

CPAP , or NIPPV .• The primary end point for the comparison between

noninvasive ventilation and standard oxygen therapy was death within 7 days after the initiation of treatment, and

• The primary end point for the comparison between NIPPV and CPAP was death or intubation within 7 days.

• A total of 1069 patients were randamized.• oxygen therapy (367 patients), CPAP (346 patients), or

NIPPV (356 patients).• Results: No significant difference in 7-day mortality between

patients receiving standard oxygen therapy (9.8%) and those undergoing noninvasive ventilation (9.5%, P=0.87).

There was no significant difference in the combined end point of death or intubation within 7 days between the two groups of patients undergoing noninvasive ventilation (11.7% for CPAP and 11.1% for NIPPV, P=0.81).

• Noninvasive ventilation was associated with greater mean improvements at 1 hour after the beginning of treatment in patient-reported dyspnea , heart rate , acidosis and hypercapnia

• No treatment-related adverse events.

CPAP or PAV

Intensive Care Med (2008)

• A prospective multicenter randomized study in the medical ICUs of three teaching hospitals.

• 36 patients with ACPE randomized to undergo either CPAP or PAV

Asthma &NIPPV

• Number of studies investigating the use of NPPV in acute asthma exacerbations is limited

• Available data suggests that it is safe .• There are some studies to support the use of

BiPAP for acute asthma exacerbations in the pediatric population .

• Lot of papers that address the question there are

• Only 3 completed RCTs and all these have relatively small numbers.

Addition of NIV in treating status asthmaticus is safe and well tolerated.

NIV shows promise as a beneficial adjunct to conventional medical treatment.

further prospective investigation is warranted

Conclusion

Addition of NIV in treating status asthmaticus is safe and well tolerated.

NIV shows promise as a beneficial adjunct to conventional medical treatment.

further prospective investigation is warranted .

MECH ON ACTION

• May have a direct bronchodilating effect

• Offset intrinsic PEEP,

• Recruit collapsed alveoli,

• Improve ventilation–perfusion mismatch

• Reduce the work of breathing

NIPPV & Pneumonia

– Noninvasive ventilation not established to be beneficial

– Secretions may be limiting factor– Improvement with noninvasive ventilation best

achieved in patients also with COPD– Hypercapnic respiratory acidosis may define

group likely to respond– Decrease in intubation rate and mortality may

be limited to those also with COPD

Conclusions• Indications for NIV in the acute setting have been broadening• Choosing the right pt for the NIV is very important for success (patients

who do not require emergent intubation and lack contraindications to NPPV).

• The best-established indications remain acute exacerbations of COPD ( BiPAP- grade 1A level of evidence) and acute pulmonary edema( CPAP, BiPAP- grade 1A).

• In ACPE , The greatest benefits are realized in relief of symptoms and dyspnea, but the decrease in intubation and mortality rates is not a universal experience

• Strong evidence supports the use of NIV for immunocompromised patients with acute respiratory failure.

• Weaker evidence supports use in selected patients with acute exacerbations of asthma( grade 1B) , cystic fibrosis, pneumonia , and deteriorating obstructive sleep apnea.

.

• Higher quality clinical trials are needed to confirm that NPPV is beneficial to patients with severe asthma exacerbations (A trial of NPPV prior to invasive mechanical ventilation seems reasonable for patients having a severe asthma exacerbation despite initial bronchodilator therapy, if they do not require immediate intubation and have no contraindications to NPPV)

• In asthma, NIV showed Improvement in spirometry (main outcome measure) , Fewer admissions with NIV ; but intubation not an outcome measure

• NIPPV needs close attention and monitoring

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