WHY THE INTEREST IN NIV?• It avoids the need for endotracheal intubation/sedation/NMB• It reduces the occurrence of complications such as Nosocomial infection and tracheal stenosis• It decreases intensive care unit (ICU) stay and overall cost of hospitalization in selected patients• Achieves alveolar ventilation and gas exchange parameters similar to IMV• Permits removal of secretions, eating and speech Brochard L, Mancebo J, Elliott MW. Noninvasive ventilation for acute respiratory failure. Eur Respir J 2002;19(4):712-721.
DEFINITION OF NIV• Noninvasive ventilation is the delivery of ventilatory support without the need for an invasive artificial airway (an endotracheal or tracheostomy tube)• NPPV typically is administered through a nasal or an oral mask ARFC Consensus Conference: non-invasive positive pressure ventilation: consensus statement, Respir Care 42:362, 1997
Continuous Positive Airway Pressure (CPAP)• Provides a constant pressure, but no ventilatory support. So CPAP is not considered as a form of ventilation• More effective in hypoxemic than in hypercapnic states.• It requires a spontaneously breathing patient and is unable to support in the case of apnea.• Improves alveolar edema and increases functional residual capacity• Main uses are: OSA pt Congestive heart failure Am J Respir Crit Care Med 2001;163: 283–291
Noninvasive Positive Pressure Ventilation• Both pressure-cycled and volume-cycled modes are available.• Pressure-cycled ventilation is the preferred mode. In this mode, a preset pressure is applied with inspiration and expiration known as IPAP and EPAP
IPAP – Inspiratory positive airway pressure• Reduces the work of breathing – Alleviates respiratory distress – Unloads respiratory muscles – Improves respiratory muscle function Augments alveolar ventilation Reduces dead space ventilation Reduces rate related auto PEEP dynamic hyperinflation• Improves gas exchange: hypoxemia and hypercapnia Antonelli M et al, Crit Care 2000
EPAP – Expiratory positive airway pressure• Improves gas exchange: by alveolar recruitment and corrects hypoxemia• Increases FRC by preventing end exp collapse• Improves respiratory muscle fn : reduces dynamic hyperinflation advantage to the diaphragm and intercostals• Auto PEEP (Inspiratory threshold load) : Offsets intrinsic PEEP, aids triggering• Reduces re-breathing• Enhances the delivery of bronchodilators to distal bronchial tree
DIFFERENT MODES• Continuous positive airway pressure• Pressure support ventilation( IPAP alone)• Bilevel positive airway pressure: BiPAP (IPAP+ EPAP)• Proportional assist ventilation(PAV)• Assist-controlled ventilation (mask IPPV) Craig TH, Emerg Med 2002 Mehta Set al, AJRCCM 2001
CHOICE OF INTERFACES• Currently available interfaces include nasal, oronasal and facial masks, mouthpieces and helmets.• For treatment of acute respiratory failure, facial masks are most commonly used (70% of cases), followed by nasal masks (25%) and nasal pillows (5%)
NASAL MASKS• More air leakage through the mouth so fail to deliver air pressures to the lungs reliably• Better tolerance, less claustrophobia• Small dead space (104 ml vs. 250 ml facial mask)• Better ability to vocalize, expectorate, eat and drink• Resistance of the nasal passages. Limited effectiveness when the nasal resistance exceeds 5 cm H2O/L per second
ORO NASAL MASKS OR FULL FACE MASKS• It permits mouth breathing and reduce air leaks through the mouth• They may be preferred by acutely dyspneic patients who are “mouth breathers.”• They interfere more with speech, eating, and expectoration and may contribute more to claustrophobic reactions and dead space than nasal masks. Crit Care Med 2003 Vol. 31, No. 2,468-473
face mask group nasal mask groupA face mask should be the first-line strategy in the initialmanagement of hypercapnic acute respiratory failure withNIPPV. However, if NIPPV has to be prolonged, switching toa nasal mask may improve comfort by reducing face maskcomplications.
HUMIDIFICATIONS MOUTH LEAK Unidirectional inspiratory nasal airflow DRYING OF NASAL MUCOSA RELEASE OF INFLAMM. MEDIATOR INCREASE NASAL RESISTANCEDifferent types include heated or unheated Passover devices, passthrough devices, and HME, however with pressure-targetedventilators only pass-over humidifiers should be applied, sincepass through devices, and HME may compromise pressure andflow delivery and triggering.
INDICATIONS FOR ACUTE NON- INVASIVE VENTILATIONRecommended: first choice for ventilatory support in selected patients. Guideline: canbe used in appropriate patients, but careful monitoring is advised.Option: suitable for a very carefully selected and monitored minority of patients.b Best evidence for severe COPD with pH < 7.35.c In most recent review, no evidence of survival benefit
INDICATIONS FOR ACUTE NON- INVASIVE VENTILATION
INDICATIONS FOR ACUTE NON- INVASIVE VENTILATIONAmbrosino N, Vagheggini G. Noninvasive positive pressure ventilation in the acute caresetting : where are we? Eur Respir J 2008;31:874–886; and Hill NS, Brennan J,Garpestad E, Nava S. Noninvasive ventilation in acute respiratory failure . Cri t CareMed 2007; 35:2402–2407
NIPPV AND AE-COPD• NPPV has been proposed as the first-line ventilatory strategy for treatment of acute- on-chronic respiratory failure due to AECOPD.
Non-invasive positive pressure ventilation to treat respiratory failureresulting from AE-COPD Cochrane systematic review and meta-analysis
What studies showed? • A lower mortality rate (RR 0.41;95% CI 0.26–0.64) • Less need for endotracheal intubation(RR 0.42; 95% CI 0.31–0.59) • A lower rate of treatment failure (RR0.51; 95% CI 0.38–0.67) • Greater improvements in the 1-hour post treatment pH and PaCO2 levels • A lower respiratory rate • A shorter length of stay in the hospitalLightowler JV, Wedzicha JA, Elliott MW, Ram FS. Cochrane systematicreview and meta-analysis. BMJ 2003; 326:185.
USE OF NIPPV AND DIFFERENT SEVERITY OF ARFEur Respir J 2008; 31: 874–886
IDENTIFICATION OF PATIENT SUB GROUP IN AE-COPD Ann Intern Med. 2003;138:861-870This meta-analysis of 15 trials found that addingNPPV to standard care reduced rates ofendotracheal intubation, length of hospital stay, andin-hospital mortality rates in patients with AE-COPD
Selection Guidelines for NIV in the Acute Setting• Appropriate diagnosis with potential reversibility• Establish need for ventilatory assistance Moderate-to-severe respiratory distress Tachypnea (respiratory rate > 24/min for COPD, 30/min for CHF) Accessory muscle use or abdominal paradox Blood gas derangement (pH <7.35, Paco2 > 45 mm Hg, or Pao2/Fio2 <200)
Do not use this therapy if the patient Has• Respiratory arrest• Is medically unstable (hypotensive shock, uncontrolled cardiac ischemia or arrhythmias)• Cannot protect the airway (impaired cough or swallowing mechanism)• Has excessive secretions• Is agitated or uncooperative• Has facial trauma, burns, or surgery, or anatomic abnormalities interfering with mask fit• Has an Acute Physiology and Chronic Health Evaluation (APACHE) score > 29 RESPIR CARE 1997; 42:364–369 EUR RESPIR J 2005; 25:348–355; THORAX 2002; 57:192–211.
Predicting NIV Failure in COPD: Chart of Failure (baseline and 2 hrs)
CONSEQUENCES OF AUTO-PEEP• Increases the work of breathing• Worsens gas exchange• Can cause hemodynamic compromise . Reduces the preload of the right and left ventricles, decreases LV compliance and can increase RV after load by increasing PVR.Can lead to inappropriate treatment Misinterpretation of CVP AND PCWP measurements Erroneous calculations of static respiratory compliance: The true value of static compliance will be underestimated Inappropriate fluid administration or unnecessary vasopressor therapy
Auto-positive end-expiratory pressure: Mechanisms and treatment CLEVELAND CLINIC JOURNAL OF MEDICINE
CARDIOGENIC PULMONARY EDEMA The 3CPO Trial N Engl J Med 2008;359:142-51.
Primary Outcome: MortalityStandard Oxygen Therapy versus Non-invasive Ventilation Cumulative Survival 1.0 0.9 Non-invasive Ventilation Standard Oxygen Therapy P=0.685 0.8 0 10 20 30 Days
OUTCOME OF 3CPO Trial• CPAP or NIPPV was significantly better than standard oxygen therapy in the first hour of treatment in terms of the Dyspnea score Heart rate Acidosis Hypercapnia. However, there were no significant differences between groups in the 7- or 30-day mortality rates, the rates of intubation, rates of admission to the critical care unit, or in the mean length of hospital stay.
CARDIOGENIC PULMONARY EDEMA• NIV and CPAP equally and safely improve vital signs and gas exchange• To date, no trial has been sufficiently powered to confirm a mortality benefit from either technique.• At this time we cannot conclude that NIV offers any advantages over CPAP.
Potential Mechanisms of Action of CPAP and NIV in Patients With Acute CPE• CPAP Increased functional residual capacity Reduced atelectasis Reduced right-to-left intrapulmonary shunt Reduced work of breathing from improved pulmonary compliance Increased cardiac output from reduced pre-load and after-load Reduced mitral regurgitation• NIV Same benefits as CPAP Unloads the respiratory muscles Respir Care 2009;54(2):186 –195
Causes significant decrease in the heart rate due to parasympathetic tone (by CPAP induced lung inflation)Anesthesiology 2005; 103:419–28
DIASTOLIC HEART FAILURE• CPAP improves oxygenation and ventilatory parameters in all kinds of CPE.• In patients with preserved LV contractility, the hemodynamic benefit of CPAP results from a decrease in LV end-diastolic volume (preload)• CPAP, by decreasing respiratory work in patients with cardiopulmonary edema, unloads the heart from the large amount of cardiac output that supplies the respiratory muscles and improves oxygen delivery for other tissues. Chest 2005; 127:1053–1058
WHEN TO USE NIV IN ACPE?• GRAY ET AL noninvasive ventilation (CPAP or NIPPV) be considered as “adjunctive therapy” in patients with acute cardiogenic pulmonary edema who have severe respiratory distress or whose condition does not improve with pharmacologic therapy Start with CPAP•If persisting dyspnea or hypercapnia with CPAP alone, add pressure support
Respiratory Failure in ImmunocompromisedPatients RCTs have found decreased intubation shorter ICU lengths of stay and Decreased ICU mortality rates The reduced mortality is likely related to reduced infectious complications associated with NIV use VAP, other nosocomial infections, and septic shock Antonelli et al JAMA 2000; 283:235 Hilbert G, et al: N Engl J Med 2001; 344: 481
Am J Respir Crit Care Med Vol168. pp 70–76, 2003Intubated patients who met criteria to proceed in the weaningattempt but had failed a spontaneous breathing trial for 3consecutive days were considered eligible for the study
Noninvasive Ventilation during Persistent Weaning FailureA Randomized Controlled TrialMiquel Ferrer at al Am J Respir Crit Care Med Vol 168. pp 1438–1444,2003 NIV NIV
Am J Respir Crit Care Med Vol 168. pp 70–76, 2003
MECHANISMS OF IMPROVEMENT• Because patients with unsuccessful weaning are likely to develop a rapid and shallow breathing pattern, the ability of NIV to improve hypoxemia and hypercapnia by correcting such an abnormal breathing pattern might explain the benefits of NIV in these patients• Decrease period on MV will reduce the complications associated with it
OUTCOME Earlier extubation with NIV results in shorter• Mechanical ventilation• length of stay• less need for tracheotomy• lower incidence of complications, and improved survival
HYPOXAEMIC RESPIRATORY FAILURE• Several diseases may lead to hypoxaemic ARF which is defined by a PaO2/FIO2 ratio ≤300 mmHg• Result is conflicting due to heterogeneous group of clinical conditions, ARDS, pneumonia and thoracic trauma.
NIV in Acute Hypoxemic Respiratory Failure Respir Care 2009;54(12):1679 –1687
RECOMMENDATIONS IN DIFFERENT SUBGROUPSCrit Care Med 2007;35:2402–2407
RECOMMENDATIONS IN DIFFERENT SUBGROUPS• NIV cannot be recommended as routine therapy for ALI/ARDS• A cautious trial in highly selected patients with a Simplified Acute Physiology Score II ≤34 and readiness to promptly intubate if oxygenation fails to improve sufficiently within the first hour.• Trial should always be done in ICU
Predictors for failure in hypoxaemic respiratory failure• No or minimum rise in the ratio of PaO2/FIO2 after 1–2 h• Patients older than 40 years (one study)• Simplified acute physiology score >34 at admission• Presence of ARDS• CAP with or without sepsis, and multiorgan system failure
NIV IN ASTHMA• According to the British Thoracic Society Standards of Care Committee Statements:• ‘‘NPPV should not be used routinely in acute asthma, but a trial might be considered in patients not promptly responding to standard treatments’
POST OPERATIVE RESPIRATORY FAILURE• Respiratory insufficiency in patients undergoing major surgery, especially of the chest or upper abdomen, is relatively common.• After abdominal surgery, respiratory complications occur in approximately 10% of patients, and reintubation represents 30% of those complications.• Pain, splinting, and respiratory muscle dysfunction, atelectasis are likely contributors to hypoxemia and respiratory insufficiency.
POST OPERATIVE RESPIRATORYFAILURE: prevention and treatment Anesthesiology 2010; 112:453– 61
MECHANISMS OF IMPROVEMENTAlthough multiple studies support this application, further studiesneed to focus on the use of NIV following specific surgical proceduresbefore firmer recommendations can be made
Portable vs critical care ventilatorsLiesching T et al , Chest 2003
Critical care versus portable ventilators• The elaborate alarms may be counter-productive since they frequently indicate very minor air leaks that are common during NIV and not of clinical significance• Use of single limb circuits in the portable devices, which may have an effect upon CO2 elimination• While home ventilators can adequately compensate large gas leaks, ICU ventilators are not able to cope with large leaks Eur Respir J 2002; 20: 1029–1036
COMPLICATIONS• Masks- pressure ulceration on the bridge of the nose or above the ears (due to mask straps/headgear).• Conjunctival irritation may be associated with air leak around the mask.• Nasal congestion, oral or nasal dryness and insufflation of air into the stomach.• Claustrophobia
COMPLICATIONS• More serious complications include aspiration pneumonia, haemodynamic compromise associated with increased intrathoracic pressures and pneumothorax.• The occurrence of each of these more serious complications, however, has been identified as less than 5% (Hill 2006).
COMPLICATIONS• Significant air leak for most bi level devices is 0.4L/sec above intentional leak• Decreased effectiveness of ventilation (NIPSV)– Inability to maintain optimal pressures (CPAP)– Sleep fragmentation– Inability to trigger ventilator– Prolonged inspiratory time– Greater oxygen requirementLeak Monitoring in Noninvasive Ventilation Arch Bronconeumol 2004;40(11):508-17
EXTUBATION FAILURE• USE OF NIV routinely after extubation for reducing extubation failure not recommended• Can be recommended in high risk patients after extubation Age>65 APACHEII>12 at the time of ext. Cardiac failure at the time of intub.KHILNANI ET AL, IJCCM,2006GUIDELINES FOR NIV IN ARF
PREDICTORS OF FAILURE b likelihood of failure 50% if any 3 and 82% if all 4 present at baseline; 75% if any three and 99% if all four present after 2 hrs of NIV. Ambrosino Thorax ’94 Confalonieri, Rana, Antonelli ICM 2001, Antonelli ,CCM 2006
WEANING METHODS• SBT after 48hrs stabilization on MV• FAIL SBT>STABILIZE WITH FULL MV SUPPORT FOR 1 HR> EXTUBATE AND PUT ON NIVGUIDELINES FOR NIV IN ARFIJCCM,2006