ventilation

The Role of Mechanical Ventilation in ARF Management

by ICU Ventilator

Mechanical ventilation plays a critical role in addressing the pathophysiological mechanisms underlying acute respiratory failure (ARF). By correcting gas exchange abnormalities, reducing respiratory muscle workload, and preventing complications, it provides essential support for patients in critical conditions (1,5,7,8). Below, specific mechanisms of mechanical ventilation are linked to the pathophysiological issues they target to enhance clarity and coherence.

Correction of Hypoxemia

One of the primary goals of mechanical ventilation in ARF is to address hypoxemia caused by mechanisms such as ventilation-perfusion (V/Q) mismatch, shunting, or diffusion impairment.

  • Mechanism: Mechanical ventilation increases the fraction of inspired oxygen (FiO₂), ensuring higher oxygen availability in the alveoli, which is crucial for patients with reduced oxygenation due to pneumonia, ARDS, or pulmonary embolism.
  • PEEP (Positive End-Expiratory Pressure): PEEP prevents alveolar collapse during exhalation by maintaining positive pressure in the lungs, thereby improving functional residual capacity (FRC). This is particularly effective in conditions involving alveolar instability, such as ARDS or atelectasis.
  • Link to Pathophysiology: In cases of shunting, where blood bypasses ventilated alveoli, PEEP recruits collapsed alveoli and redistributes ventilation, reducing hypoxemia.

Removal of Hypercapnia

Hypercapnia in ARF arises from hypoventilation or increased dead space, as seen in conditions like COPD exacerbations or severe obesity hypoventilation syndrome.

  • Mechanism: Mechanical ventilation increases minute ventilation by optimizing tidal volume (VT) and respiratory rate. By enhancing the removal of carbon dioxide, it normalizes arterial pH and relieves respiratory acidosis.
  • Pressure-Control Ventilation (PCV): PCV is particularly beneficial in hypercapnic ARF as it delivers preset pressure during inspiration, ensuring adequate ventilation while minimizing airway pressures.
  • Link to Pathophysiology: In hypoventilation-related hypercapnia, increasing ventilatory support reduces carbon dioxide retention, reversing acidemia and preventing hemodynamic instability.

Reduction of Work of Breathing

ARF often places a high workload on respiratory muscles, leading to fatigue and eventual failure, especially in conditions like COPD exacerbations or severe asthma.

  • Mechanism: Mechanical ventilation reduces the effort required to breathe by delivering positive pressure during inspiration. Modes like pressure support ventilation (PSV) and assist-control ventilation (ACV) enable respiratory muscle rest while maintaining adequate ventilation.
  • Link to Pathophysiology: By decreasing the work of breathing, mechanical ventilation prevents respiratory muscle exhaustion, a key contributor to hypercapnic ARF.

Alveolar Recruitment and Stabilization

Alveolar recruitment strategies are critical for restoring effective gas exchange in conditions like ARDS, where alveolar collapse and severe V/Q mismatch are common.

  • Mechanism: PEEP and lung-protective ventilation strategies, such as low tidal volumes, recruit and stabilize alveoli, increasing the surface area available for gas exchange.
  • Link to Pathophysiology: In ARDS, where alveolar collapse exacerbates shunting, PEEP opens collapsed alveoli, improving oxygenation and reducing the severity of hypoxemia.

Prevention of Secondary Complications

Mechanical ventilation provides controlled respiratory support that reduces the risk of secondary complications such as aspiration, ventilator-associated pneumonia (VAP), or multi-organ failure.

  • Mechanism: Secure airway management with invasive mechanical ventilation protects against aspiration, while precise ventilator settings minimize barotrauma and ventilator-induced lung injury (VILI).
  • Link to Pathophysiology: By addressing hypoxemia and hypercapnia, mechanical ventilation prevents systemic complications like hypoxia-induced multi-organ failure and maintains hemodynamic stability.

Mechanical ventilation compensates for the physiological disruptions seen in ARF by targeting specific mechanisms like V/Q mismatch, diffusion impairment, and increased work of breathing. Each intervention, whether optimizing oxygenation, reducing carbon dioxide levels, or stabilizing alveolar function, is tailored to the patient’s underlying pathology.

This ensures effective management of ARF while minimizing complications, emphasizing the indispensable role of mechanical ventilation in critical care settings (1-8,10).

Types of Mechanical Ventilation

Mechanical ventilation is classified into invasive and non-invasive methods, each with specific applications based on the patient’s condition and therapeutic needs (9-11). Both types play a vital role in the management of acute respiratory failure (ARF), with the choice determined by the severity of respiratory dysfunction and the clinical response to treatment (10).

Non-Invasive Ventilation (NIV)

Non-invasive ventilation delivers respiratory support through a mask or nasal interface, avoiding the need for intubation. It is particularly effective in patients with mild to moderate ARF who are conscious and able to protect their airway.

  • Mechanism: NIV enhances oxygenation and ventilation using positive airway pressure, which prevents alveolar collapse and reduces the work of breathing.
  • Common Modes:
    • Continuous Positive Airway Pressure (CPAP): Maintains constant positive airway pressure throughout the respiratory cycle, improving oxygenation in conditions such as cardiogenic pulmonary edema.
    • Bilevel Positive Airway Pressure (BiPAP): Alternates between inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP), facilitating both oxygenation and ventilation, particularly in hypercapnic ARF seen in COPD exacerbations.
  • Clinical Application: NIV is widely used in exacerbations of chronic conditions like COPD, mild ARDS, and heart failure, where it can stabilize gas exchange and reduce the need for intubation.

Invasive Mechanical Ventilation (IMV)

In cases where non-invasive ventilation fails to stabilize ARF or is contraindicated, invasive mechanical ventilation provides controlled respiratory support through an endotracheal or tracheostomy tube.

  • Mechanism: IMV directly accesses the airway, ensuring precise delivery of oxygen, removal of carbon dioxide, and reduction of respiratory muscle workload. It also facilitates better protection against aspiration in patients with altered mental status or significant secretions.
  • Common Modes:
    • Assist-Control Ventilation (ACV): Delivers a preset tidal volume or pressure with every breath, whether initiated by the patient or the ventilator. ACV provides full respiratory support, ideal for patients with severe ARF and minimal respiratory effort.
    • Synchronized Intermittent Mandatory Ventilation (SIMV): Combines mandatory ventilator-delivered breaths with the patient’s spontaneous breaths. It is frequently used during weaning to encourage respiratory muscle activity.
    • Pressure Support Ventilation (PSV): Supports spontaneous breathing by delivering a set inspiratory pressure. It is commonly employed during recovery or as a step-down mode in the weaning process.
  • Clinical Application: IMV is indicated in severe ARF with refractory hypoxemia, hypercapnia unresponsive to NIV, or conditions like ARDS, where invasive strategies like lung-protective ventilation and high PEEP are essential.

Non-invasive ventilation often serves as the first-line treatment in ARF. However, in some cases, such as persistent hypoxemia, rising carbon dioxide levels, or respiratory distress that worsens despite NIV, transitioning to invasive mechanical ventilation becomes necessary to ensure adequate respiratory support and prevent further deterioration (9–11). The specific criteria and clinical scenarios guiding this transition will be examined in a subsequent section.

By tailoring the type of mechanical ventilation to the patient’s condition and response, clinicians can optimize outcomes while minimizing complications.

Modes of Mechanical Ventilation for ARF Treatment

The choice of mechanical ventilation mode in acute respiratory failure (ARF) is determined by the underlying pathology, severity of respiratory compromise, and patient-specific factors (11,12). Optimizing the mode of ventilation is essential to ensure adequate gas exchange while minimizing complications (12). Below, the most commonly used modes are outlined, with an emphasis on their applications and clinical significance.

Assist-Control Ventilation (ACV)

ACV provides full respiratory support by delivering a preset tidal volume (VT) or pressure with each breath, regardless of whether the breath is initiated by the patient or the ventilator.

  • Application: This mode is typically used in severe ARF, particularly in conditions such as ARDS or pneumonia, where patients may have minimal or absent spontaneous respiratory effort.
  • Advantages: Guarantees consistent ventilation and simplifies management in critically ill patients.

Synchronized Intermittent Mandatory Ventilation (SIMV)

SIMV delivers a set number of mandatory breaths, synchronized with the patient’s spontaneous respiratory efforts, allowing for unassisted breaths in between.

  • Application: Often employed as an intermediate step in patients transitioning from full ventilatory support to spontaneous breathing, such as during the weaning process.
  • Advantages: Promotes respiratory muscle activity while providing a safety net of mandatory ventilator breaths.

Pressure Support Ventilation (PSV)

PSV augments spontaneous breathing by providing a preset level of inspiratory pressure, reducing the effort required for inspiration.

  • Application: Commonly used in patients with preserved respiratory drive, such as those recovering from ARF or during non-invasive ventilation (NIV).
  • Advantages: Improves patient comfort, reduces work of breathing, and facilitates weaning from invasive ventilation.

Volume-Controlled and Pressure-Controlled Ventilation (VCV/PCV)

  • Volume-Controlled Ventilation (VCV) delivers a preset tidal volume, with airway pressure varying depending on lung compliance and resistance.

    Application: Used in patients requiring precise control of minute ventilation, such as those with hypercapnia.
  • Pressure-Controlled Ventilation (PCV) delivers a preset pressure during inspiration, with tidal volume varying based on lung compliance.

    Application: Beneficial in patients with reduced lung compliance, such as in ARDS, to limit peak airway pressures and reduce the risk of barotrauma.

High-Frequency Oscillatory Ventilation (HFOV)

HFOV delivers very small tidal volumes at high frequencies, maintaining continuous positive airway pressure.

  • Application: A rescue strategy for refractory hypoxemia in ARDS when conventional ventilation fails.
  • Advantages: Minimizes ventilator-induced lung injury (VILI) by preventing alveolar overdistension.

Clinical Significance

The selection of the appropriate mode of mechanical ventilation in ARF is crucial for optimizing outcomes and minimizing complications. For instance, lung-protective ventilation strategies, such as low tidal volume ventilation in ARDS, reduce the risk of ventilator-induced lung injury (11).
Modes like SIMV and PSV play key roles in facilitating weaning and restoring spontaneous respiratory function (11). By tailoring ventilation modes to the individual needs of patients, clinicians can address the specific pathophysiological challenges of ARF while improving survival and recovery rates (11-15).

Advanced Modes of Mechanical Ventilation: ASV, SAV, and NAVA

With the evolution of mechanical ventilation, advanced modes like Adaptive Support Ventilation (ASV), SmartCare/Automated Ventilation (SAV), and Neurally Adjusted Ventilatory Assist (NAVA) have emerged as pivotal tools in modern respiratory care. These modes leverage intelligent algorithms and neural control mechanisms to enhance patient outcomes, improve synchronization, and simplify clinical workflows. Below is a comprehensive discussion of each mode and its clinical significance (23-25).

Adaptive Support Ventilation (ASV)

  • What is ASV?
     ASV is an intelligent mode of mechanical ventilation that automatically adjusts ventilatory support based on the patient’s respiratory mechanics and effort. It uses algorithms to calculate the ideal tidal volume and respiratory rate based on the patient’s predicted body weight, lung compliance, and airway resistance (22-25).
  • How ASV Works:
    • ASV continuously monitors the patient’s spontaneous breathing.
    • It dynamically adjusts the inspiratory pressure and ventilatory rate to meet the patient’s metabolic demand while preventing over-distension or atelectasis.
    • This mode ensures minimal work of breathing while maintaining target minute ventilation.
  • Benefits of ASV:
    • Automatically reduces support as the patient’s respiratory effort improves, facilitating a smooth transition from controlled to spontaneous breathing.
    • Decreases the risk of hyperventilation, barotrauma, and ventilator-induced lung injury (VILI) (23,24).
    • Improves patient-ventilator synchrony, reducing discomfort and sedation requirements (24).
  • Evidence and Clinical Applications:
    • Studies have shown ASV to be effective in both acute and chronic respiratory failure. For example, research published in Critical Care (Arnal et al., 2008) demonstrated that ASV reduced ventilation duration compared to traditional modes in post-operative ICU patients (26).
    • It is widely used in settings requiring dynamic adaptation, such as weaning and managing variable lung mechanics in conditions like ARDS or COPD exacerbations (27).

SmartCare/Automated Ventilation (SAV)

  • What is SAV?
     SmartCare/Automated Ventilation is a closed-loop ventilation system designed primarily to automate the weaning process. It uses an artificial intelligence algorithm to assess and adjust ventilatory support based on real-time patient parameters (25,28-31).
  • How SAV Works:
    • SAV continuously monitors the patient’s respiratory rate, tidal volume, and end-tidal carbon dioxide (EtCO₂).
    • Based on these parameters, it adjusts pressure support levels to ensure adequate ventilation and oxygenation.
    • When the algorithm determines that the patient can sustain spontaneous breathing, it suggests readiness for extubation.
  • Benefits of SAV:
    • Speeds up the weaning process by reducing the need for manual adjustments (22-31).
    • Prevents premature or delayed extubation by following evidence-based criteria.
    • Reduces the workload for ICU staff and standardizes the weaning process.
  • Evidence and Clinical Applications:
    • Clinical trials, such as those published in Intensive Care Medicine (Lellouche et al., 2006), have shown that SmartCare reduces the duration of mechanical ventilation and ICU stay while improving extubation success rates (31).
    • SAV is especially useful in ICUs with high patient volumes or variability in care protocols (24-31).

Neurally Adjusted Ventilatory Assist (NAVA)

  • What is NAVA
    Neurally Adjusted Ventilatory Assist (NAVA) is an advanced mode of mechanical ventilation that directly uses the patient’s neural respiratory drive to control ventilatory support. Unlike traditional modes that rely on airway pressure or flow triggers, NAVA is driven by electrical activity in the diaphragm (Edi), offering highly personalized and precise ventilation (25-34).
  • How NAVA Works?

    Edi Catheter:
    A specialized nasogastric catheter detects electrical signals from the diaphragm during the patient’s spontaneous breathing efforts.

    Signal Processing:
    These signals (Edi) are analyzed in real-time to determine the timing, duration, and intensity of inspiratory effort.

    Ventilator Response:
    The ventilator delivers pressure support proportional to the patient’s effort, ensuring optimal synchronization and avoiding over-assistance or under-assistance.
  • Advantages of NAVA

    Improved Patient-Ventilator Synchrony:
    NAVA directly responds to the patient’s neural respiratory signals, eliminating delays and mismatches that occur with pressure or flow triggering.
    Reduces asynchrony-related complications, such as ineffective efforts, double triggering, and patient discomfort.

    Reduction in Sedation Needs:
    By providing natural, synchronized support, NAVA minimizes the discomfort associated with mechanical ventilation, reducing the need for sedatives.

    Enhanced Respiratory Muscle Protection:
    Unlike traditional modes that can over-assist, leading to respiratory muscle atrophy, NAVA ensures the diaphragm remains active, maintaining muscle strength and endurance.

    Personalized Ventilation:
    Adapts dynamically to the patient’s changing respiratory demands, particularly in conditions like ARDS, COPD, or neuromuscular disorders.
  • Clinical Applications of NAVA

    ARDS and Acute Respiratory Failure (ARF):
    NAVA provides lung-protective ventilation by avoiding overdistension and barotrauma while maintaining synchrony (38).

    Neonatal and Pediatric Ventilation:
    Especially useful in premature infants and pediatric patients, where synchrony challenges are common with traditional modes (36-37,39-43).

    Weaning:
    Facilitates a gradual reduction in ventilatory support by responding to the patient’s natural efforts (44-45).

    NAVA represents a significant advancement in mechanical ventilation, focusing on precision and patient-centric care by using the diaphragm’s electrical activity to guide support. Its ability to enhance patient-ventilator synchrony, reduce sedation needs, and protect respiratory muscles makes it an invaluable mode in both adult and pediatric populations. When combined with other modes like ASV and SAV, NAVA provides a versatile and comprehensive approach to managing acute respiratory failure.

When to Transition from Non-Invasive Mechanical Ventilation (NIMV) to Invasive Mechanical Ventilation (IMV) in ARF

Non-invasive mechanical ventilation (NIMV) is often the first-line treatment for acute respiratory failure (ARF) in specific conditions like COPD exacerbations or mild-to-moderate hypoxemia. However, in some cases, NIMV may fail to provide adequate support, requiring a transition to invasive mechanical ventilation (IMV) to prevent further deterioration. Here are the key indicators and clinical scenarios to consider transitioning:

1. Worsening Gas Exchange Despite NIMV

  • Signs:
    • Persistent or worsening hypoxemia (PaO₂ < 60 mmHg on FiO₂ ≥ 0.6).
    • Rising PaCO₂ (> 50 mmHg) with associated respiratory acidosis (pH < 7.25).
  • Reason: Indicates that NIMV is insufficient to meet oxygenation or ventilation demands.

2. Severe Respiratory Distress

  • Signs:
    • Increased respiratory rate (> 35 breaths/min).
    • Use of accessory muscles, paradoxical breathing, or nasal flaring.
    • Inability to speak in full sentences due to dyspnea.
  • Reason: Suggests that the patient’s work of breathing has exceeded the support provided by NIMV, risking respiratory muscle fatigue and collapse.

3. Altered Mental Status

  • Signs:
    • Confusion, agitation, or inability to cooperate with NIMV.
    • Progression to somnolence or coma (indicating hypercapnia or hypoxemia affecting cerebral function).
  • Reason: Neurological impairment reduces the ability to maintain spontaneous breathing or adhere to NIMV.

4. Hemodynamic Instability

  • Signs:
    • Hypotension (systolic blood pressure < 90 mmHg) unresponsive to fluid resuscitation.
    • Shock or signs of reduced cardiac output.
  • Reason: Indicates systemic compromise that requires better oxygenation and ventilation control via IMV.

5. Risk of Aspiration or Airway Protection Issues

  • Signs:
    • Inability to clear secretions or significant mucus plugging.
    • Frequent vomiting or risk of aspiration (e.g., altered consciousness).
  • Reason: IMV is necessary to secure the airway with an endotracheal tube to prevent aspiration-related complications.

6. Failure to Tolerate NIMV

  • Signs:
    • Poor mask seal due to facial anatomy or agitation.
    • Skin breakdown or discomfort causing discontinuation of therapy.
  • Reason: Intolerance to NIMV can reduce adherence, rendering it ineffective.

7. No Clinical Improvement Within 1–2 Hours of NIMV

  • Signs:
    • Lack of improvement in respiratory rate, gas exchange, or oxygenation after 1–2 hours of optimal NIMV.
  • Reason: Delaying the switch to IMV increases the risk of respiratory arrest and worsens outcomes.

The decision to switch from NIMV to IMV in ARF should be guided by clinical judgment, monitoring of gas exchange, respiratory mechanics, and overall patient stability. Early recognition of NIMV failure and timely intubation improve outcomes and prevent complications associated with delayed intervention (12-14, 16-21).

References

  1. Kapil S, Wilson JG. Mechanical Ventilation in Hypoxemic Respiratory Failure. Emerg Med Clin North Am. 2019;37(3):431-444. doi:10.1016/j.emc.2019.04.005
  2. Delerme S, Ray P. Acute respiratory failure in the elderly: diagnosis and prognosis. Age Ageing. 2008;37(3):251-257. doi:10.1093/ageing/afn060
  3. Antro C, Merico F, Urbino R, Gai V. Non-invasive ventilation as a first-line treatment for acute respiratory failure: “real life” experience in the emergency department. Emerg Med J. 2005;22(11):772-777. doi:10.1136/emj.2004.018309
  4. Piraino T. Noninvasive Respiratory Support in Acute Hypoxemic Respiratory Failure. Respir Care. 2019;64(6):638-646. doi:10.4187/respcare.06735
  5. Abellan C, Bertin C, Fumeaux T, Carrel L. Insuffisance respiratoire aiguë : prise en charge hospitalière non invasive [Acute respiratory failure : non-invasive hospital management]. Rev Med Suisse. 2020;16(705):1636-1644.
  6. Munshi L, Mancebo J, Brochard LJ. Noninvasive Respiratory Support for Adults with Acute Respiratory Failure. N Engl J Med. 2022;387(18):1688-1698. doi:10.1056/NEJMra2204556
  7. Pisani L, Corcione N, Nava S. Management of acute hypercapnic respiratory failure. Curr Opin Crit Care. 2016;22(1):45-52. doi:10.1097/MCC.0000000000000269
  8. Liu YJ, Zhao J, Tang H. Non-invasive ventilation in acute respiratory failure: a meta-analysis. Clin Med (Lond). 2016;16(6):514-523. doi:10.7861/clinmedicine.16-6-514
  9. Pham T, Brochard LJ, Slutsky AS. Mechanical Ventilation: State of the Art. Mayo Clin Proc. 2017;92(9):1382-1400. doi:10.1016/j.mayocp.2017.05.004
  10. Tobin MJ, Laghi F, Jubran A. Ventilatory failure, ventilator support, and ventilator weaning. Compr Physiol. 2012;2(4):2871-2921. doi:10.1002/cphy.c110030
  11. Tobin, M. J. (2013). Principles and practice of mechanical ventilation, 3e. McGraw-Hill Education LLC.
  12. Pinsky MR. Toward a better ventilation strategy for patients with acute lung injury. Crit Care. 2000;4(4):205-206. doi:10.1186/cc695
  13. Rochwerg B, Brochard L, Elliott MW, et al. Official ERS/ATS clinical practice guidelines: noninvasive ventilation for acute respiratory failure. Eur Respir J. 2017;50(2):1602426. Published 2017 Aug 31. doi:10.1183/13993003.02426-2016
  14. Torres A, Niederman MS, Chastre J, et al. International ERS/ESICM/ESCMID/ALAT guidelines for the management of hospital-acquired pneumonia and ventilator-associated pneumonia: Guidelines for the management of hospital-acquired pneumonia (HAP)/ventilator-associated pneumonia (VAP) of the European Respiratory Society (ERS), European Society of Intensive Care Medicine (ESICM), European Society of Clinical Microbiology and Infectious Diseases (ESCMID) and Asociación Latinoamericana del Tórax (ALAT). Eur Respir J. 2017;50(3):1700582. Published 2017 Sep 10. doi:10.1183/13993003.00582-2017
  15. Oczkowski S, Ergan B, Bos L, et al. ERS clinical practice guidelines: high-flow nasal cannula in acute respiratory failure. Eur Respir J. 2022;59(4):2101574. Published 2022 Apr 14. doi:10.1183/13993003.01574-2021
  16. Luo F, Annane D, Orlikowski D, et al. Invasive versus non-invasive ventilation for acute respiratory failure in neuromuscular disease and chest wall disorders. Cochrane Database Syst Rev. 2017;12(12):CD008380. Published 2017 Dec 4. doi:10.1002/14651858.CD008380.pub2
  17. Blumenthal JA, Duvall MG. Invasive and noninvasive ventilation strategies for acute respiratory failure in children with coronavirus disease 2019. Curr Opin Pediatr. 2021;33(3):311-318. doi:10.1097/MOP.0000000000001021
  18. Shang P, Zhu M, Baker M, Feng J, Zhou C, Zhang HL. Mechanical ventilation in Guillain-Barré syndrome. Expert Rev Clin Immunol. 2020;16(11):1053-1064. doi:10.1080/1744666X.2021.1840355
  19. Davidson AC, Banham S, Elliott M, et al. BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults [published correction appears in Thorax. 2017 Jun;72(6):588. doi: 10.1136/thoraxjnl-2015-208209corr1]. Thorax. 2016;71 Suppl 2:ii1-ii35. doi:10.1136/thoraxjnl-2015-208209      
  20. Kress JP, O’Connor MF, Schmidt GA. Clinical examination reliably detects intrinsic positive end-expiratory pressure in critically ill, mechanically ventilated patients. Am J Respir Crit Care Med. 1999;159(1):290-294. doi:10.1164/ajrccm.159.1.9805011
  21. Rittayamai N, Katsios CM, Beloncle F, Friedrich JO, Mancebo J, Brochard L. Pressure-Controlled vs Volume-Controlled Ventilation in Acute Respiratory Failure: A Physiology-Based Narrative and Systematic Review. Chest. 2015;148(2):340-355. doi:10.1378/chest.14-3169
  22. Brunner JX, Iotti GA. Adaptive Support Ventilation (ASV). Minerva Anestesiol. 2002;68(5):365-368.
  23. Dai YL, Hsu RJ, Huang HK, et al. Adaptive support ventilation attenuates postpneumonectomy acute lung injury in a porcine model. Interact Cardiovasc Thorac Surg. 2020;31(5):718-726. doi:10.1093/icvts/ivaa157
  24. Buiteman-Kruizinga LA, Mkadmi HE, Schultz MJ, Tangkau PL, van der Heiden PLJ. Comparison of Mechanical Power During Adaptive Support Ventilation Versus Nonautomated Pressure-Controlled Ventilation-A Pilot Study. Crit Care Explor. 2021;3(2):e0335. Published 2021 Feb 15. doi:10.1097/CCE.0000000000000335
  25. Fernández J, Miguelena D, Mulett H, Godoy J, Martinón-Torres F. Adaptive support ventilation: State of the art review. Indian J Crit Care Med. 2013;17(1):16-22. doi:10.4103/0972-5229.112149
  26. Arnal JM, Wysocki M, Nafati C, et al. Automatic selection of breathing pattern using adaptive support ventilation. Intensive Care Med. 2008;34(1):75-81. doi:10.1007/s00134-007-0847-0
  27. Zhu F, Gomersall CD, Ng SK, Underwood MJ, Lee A. A randomized controlled trial of adaptive support ventilation mode to wean patients after fast-track cardiac valvular surgery. Anesthesiology. 2015;122(4):832-840. doi:10.1097/ALN.0000000000000589
  28. Rose L, Schultz MJ, Cardwell CR, Jouvet P, McAuley DF, Blackwood B. Automated versus non-automated weaning for reducing the duration of mechanical ventilation for critically ill adults and children. Cochrane Database Syst Rev. 2014;2014(6):CD009235. Published 2014 Jun 10. doi:10.1002/14651858.CD009235.pub3
  29. Rose L, Schultz MJ, Cardwell CR, Jouvet P, McAuley DF, Blackwood B. Automated versus non-automated weaning for reducing the duration of mechanical ventilation for critically ill adults and children: a cochrane systematic review and meta-analysis. Crit Care. 2015;19(1):48. Published 2015 Feb 24. doi:10.1186/s13054-015-0755-6
  30. Wysocki M, Jouvet P, Jaber S. Closed loop mechanical ventilation. J Clin Monit Comput. 2014;28(1):49-56. doi:10.1007/s10877-013-9465-2
  31. Lellouche F, Mancebo J, Jolliet P, et al. A multicenter randomized trial of computer-driven protocolized weaning from mechanical ventilation. Am J Respir Crit Care Med. 2006;174(8):894-900. doi:10.1164/rccm.200511-1780OC
  32. Shah SD, Anjum F. Neurally Adjusted Ventilatory Assist (NAVA). In: StatPearls. Treasure Island (FL): StatPearls Publishing; May 22, 2023.
  33. Navalesi P, Longhini F. Neurally adjusted ventilatory assist. Curr Opin Crit Care. 2015;21(1):58-64. doi:10.1097/MCC.0000000000000167
  34. Sheng Y, Shao W, Wang Y, Kang X, Hu R. Zhonghua Wei Zhong Bing Ji Jiu Yi Xue. 2023;35(11):1229-1232. doi:10.3760/cma.j.cn121430-20230222-00101
  35. Vahedi NB, Ramazan-Yousif L, Andersen TS, Jensen HI. Implementation of Neurally Adjusted Ventilatory Assist (NAVA): Patient characteristics and staff experiences. J Healthc Qual Res. 2020;35(4):253-260. doi:10.1016/j.jhqr.2020.03.008
  36. Mandyam S, Qureshi M, Katamreddy Y, et al. Neurally Adjusted Ventilatory Assist Versus Pressure Support Ventilation: A Comprehensive Review. J Intensive Care Med. 2024;39(12):1194-1203. doi:10.1177/08850666231212807
  37. Sugunan P, Hosheh O, Garcia Cusco M, Mildner R. Neurally-Adjusted Ventilatory Assist (NAVA) versus Pneumatically Synchronized Ventilation Modes in Children Admitted to PICU. J Clin Med. 2021;10(15):3393. Published 2021 Jul 30. doi:10.3390/jcm10153393
  38. Umbrello M, Antonucci E, Muttini S. Neurally Adjusted Ventilatory Assist in Acute Respiratory Failure-A Narrative Review. J Clin Med. 2022;11(7):1863. Published 2022 Mar 28. doi:10.3390/jcm11071863
  39. Beck J, Emeriaud G, Liu Y, Sinderby C. Neurally-adjusted ventilatory assist (NAVA) in children: a systematic review. Minerva Anestesiol. 2016;82(8):874-883.
  40. Minamitani Y, Miyahara N, Saito K, Kanai M, Namba F, Ota E. Noninvasive neurally-adjusted ventilatory assist in preterm infants: a systematic review and meta-analysis. J Matern Fetal Neonatal Med. 2024;37(1):2415373. doi:10.1080/14767058.2024.2415373
  41.  Fang SJ, Su CH, Liao DL, et al. Neurally adjusted ventilatory assist for rapid weaning in preterm infants. Pediatr Int. 2023;65(1):e15360. doi:10.1111/ped.15360
  42. Rossor TE, Hunt KA, Shetty S, Greenough A. Neurally adjusted ventilatory assist compared to other forms of triggered ventilation for neonatal respiratory support. Cochrane Database Syst Rev. 2017;10(10):CD012251. Published 2017 Oct 27. doi:10.1002/14651858.CD012251.pub2
  43. Stein H, Beck J, Dunn M. Non-invasive ventilation with neurally adjusted ventilatory assist in newborns. Semin Fetal Neonatal Med. 2016;21(3):154-161. doi:10.1016/j.siny.2016.01.006
  44. Liu L, Xu X, Sun Q, et al. Neurally Adjusted Ventilatory Assist versus Pressure Support Ventilation in Difficult Weaning: A Randomized Trial. Anesthesiology. 2020;132(6):1482-1493. doi:10.1097/ALN.0000000000003207
  45. Yuan X, Lu X, Chao Y, et al. Neurally adjusted ventilatory assist as a weaning mode for adults with invasive mechanical ventilation: a systematic review and meta-analysis. Crit Care. 2021;25(1):222. Published 2021 Jun 29. doi:10.1186/s13054-021-03644-z

Biobite_Etco2

What is EtCO₂?

by BioBites

EtCO₂ (End-Tidal Carbon Dioxide) refers to the measurement of the carbon dioxide concentration in exhaled air at the end of expiration. It is typically expressed in millimeters of mercury (mmHg) and measured using a capnography device. It provides critical insights into the respiratory system, cardiac circulation, and metabolism.

At the end of the respiratory cycle, during exhalation, EtCO₂ represents the peak concentration of carbon dioxide (CO₂) in the exhaled gas. This value forms the basis of EtCO₂ monitoring. By reflecting the interaction between the respiratory system, circulation, and metabolism, it plays a crucial role in assessing the patient’s overall condition.

Normal EtCO₂ Values

The normal EtCO₂ level typically ranges between 35 and 45 mmHg.

  • Low EtCO₂: May indicate conditions such as hyperventilation, low cardiac output, or pulmonary embolism.
  • High EtCO₂: May suggest hypoventilation, excessive metabolic activity, or inadequate ventilator settings.

Monitoring EtCO₂ levels with mechanical ventilators plays a critical role in evaluating a patient’s respiratory status and the effectiveness of ventilation. This monitoring is performed using capnography devices, which are often integrated into the ventilator system.

EtCO₂ Monitoring Methods

  1. Mainstream Capnography
    • How It Works: The sensor is placed between the endotracheal or tracheostomy tube and the breathing circuit. The patient’s exhaled air passes directly through the sensor, and CO₂ concentration is measured in real-time.
    • Advantages: Provides instantaneous and accurate measurements with minimal delay during exhalation.
    • Disadvantages: The sensor’s weight and heat may cause discomfort, particularly for small children or frail patients.
  2. Sidestream Capnography
    • How It Works: A small gas sample is drawn from the breathing circuit and delivered to the analyzer within the device. This method can also be used for non-intubated patients.
    • Advantages: Compatible with various breathing circuits and suitable for patients who do not require intubation.
    • Disadvantages: Condensation may accumulate in the sampling line, potentially affecting measurement accuracy.

Ventilation Efficiency Through EtCO₂ Monitoring

EtCO₂ monitoring is a direct method to evaluate ventilation efficiency. It demonstrates how effectively the respiratory system eliminates carbon dioxide (CO₂) and assesses the efficiency of CO₂ removal produced through metabolic processes via ventilation. Ventilation efficiency is evaluated in various clinical conditions using EtCO₂ levels and capnogram analyses.

  1. Hypoventilation (Decreased Ventilation):
    • EtCO₂ Level: Increased (typically > 45 mmHg).
    • Cause: Inadequate elimination of CO₂ by the lungs.
    • Clinical Conditions: Respiratory depression, sedation, neuromuscular blockade, obesity hypoventilation syndrome.
    • Effect: Elevated EtCO₂ levels indicate the need to enhance ventilation.
  2. Hyperventilation (Increased Ventilation):
    • EtCO₂ Level: Decreased (typically < 35 mmHg).
    • Cause: Excessive elimination of CO₂.
    • Clinical Conditions: Anxiety, pain, response to hypoxia, compensatory mechanisms.
    • Effect: A reduction in ventilation rate or tidal volume may be necessary.
  3. Increased Alveolar Dead Space:
    • EtCO₂ Level: Decreased, but arterial CO₂ (PaCO₂) remains elevated.
    • Cause: Reduced pulmonary perfusion or ventilation-perfusion (V/Q) mismatch.
    • Clinical Conditions: Pulmonary embolism, low cardiac output, shock.
    • Effect: The difference between EtCO₂ and PaCO₂ increases (EtCO₂-PaCO₂ gradient).
  4. Circulatory Failure:
    • EtCO₂ Level: Decreased.
    • Cause: Reduced cardiac output decreases the amount of CO₂ delivered to the alveoli.
    • Clinical Conditions: Cardiac arrest, low-perfusion shock.
    • Effect: Used to monitor the effectiveness of CPR; an increase in EtCO₂ indicates the restoration of circulation.

FAQs

  1. What is the normal EtCO₂ value?
    The normal range is between 35-45 mmHg.
  2. What does low EtCO₂ mean?
    Low EtCO₂ refers to a condition where the carbon dioxide level in exhaled air is below normal. This may indicate issues related to ventilation, perfusion, or metabolism. EtCO₂ levels below 35 mmHg are typically referred to as hypocapnia.
  3. What are the causes of low EtCO₂ on a ventilator?
    Low EtCO₂ is commonly caused by factors such as hyperventilation, hypoperfusion, airway issues, or decreased metabolic activity.

References

  • Aminiahidashti, Hamed, et al. “Applications of end-tidal carbon dioxide (ETCO2) monitoring in emergency department; a narrative review.” Emergency 6.1 (2018).
  • Trilĺo, Giulio, Martin von Planta, and Fulvio Kette. “ETCO2 monitoring during low flow states: clinical aims and limits.” Resuscitation 27.1 (1994): 1-8.
  • Miner, James R., William Heegaard, and David Plummer. “End‐tidal carbon dioxide monitoring during procedural sedation.” Academic Emergency Medicine 9.4 (2002): 275-280.
  • Paiva, Edison F., James H. Paxton, and Brian J. O’Neil. “The use of end-tidal carbon dioxide (ETCO2) measurement to guide management of cardiac arrest: a systematic review.” Resuscitation 123 (2018): 1-7.
Non-Invasive Ventilation Blog Cover Photo

Advancement in Non-Invasive Ventilation

by with No Comment Uncategorized

Dated to the 1940s, Non-invasive Ventilation has been undergoing a series of changes with various modifications in designs and techniques. This improvement in ventilator modes has exceeded imaginations and has brought a lot of technical healthcare solutions to diverse medical problems.

Evolution of Non-Invasive Ventilation Technology

NIV as a mode of ventilation has a great impact in the intensive care unit, as it provides a life-changing option that produces more positive outcomes. In addition, its impact on humanity is much more than an invention but one with immeasurable support and medical advancement that comes with a decrease in problems associated with intubation. 

This article shall discuss some of the clinical importance of non-invasive ventilation in comparison with the invasive method, its impact on patient outcomes, its various technical and clinical benefits, alongside some of the future trends NIV possesses.

Non-Invasive Ventilation photo

What’s Non-Invasive Ventilation?

One of the special modes of ventilation that does not require the use of a penetrating apparatus (endotracheal intubation) to aid respiration is known as Non-invasive ventilation (NIV). This is a unique method that is often employed to reduce complications associated with invasive ventilation eg. acute respiratory failure, airway disorder, etc. It is a technique with various forms of suitable designs and modifications that help in maintaining chronic respiratory conditions.

What Are The Clinical Benefits And Patient Outcomes of Positive Pressure Ventilation (NIV)?

Assisted ventilation in humans comes in various ways, one of which is the process of using positive pressure to aerate the lungs. This mode of ventilation is often called Positive pressure ventilation. In most cases, this method is always utilized in a non-invasive ventilation system with diverse advantages and benefits compared to others. 

non invasive ventilation photo 2

Medical Benefits and Technological Advancement of Non-invasive Ventilation

  1. Special Treatment Provision: Non-invasive ventilation in the healthcare system serves as a special equipment that is used for the treatment of diverse chronic and mild conditions. Oftentimes, this positive pressure ventilation device in the BiPAP method serves as a standard unique treatment method recommended for some specific respiratory failure and occasional health safety (OHS) e.g. AHRF, pneumonia, etc.
  2. Used for Obstructive sleep apnea: Due to NIVs’ evolving features (i.e. a developed user interface), it is often utilized in many chronic and acute respiratory cases such as the treatment of obstructive sleeping apnea (OSA). This evolution has produced facial and nasal means of breathing pressure (CPAP) aimed at treating sleep-related respiratory disorders.
  3. Chronic Respiratory Management: Currently, NIV is a ventilator mode used as a proven treatment for patients with COPD problems and related chronic respiratory problems like neuromuscular abnormalities. 
Non Invasive Ventilation

 Technological Advancement of NIV Ventilator Mode

  1. Advanced Human Interface: More effective mask designs that have stronger sealing qualities, and air-leakage reduction which improve patient comfort are some NIV distinct attributes. These features mostly allow usage by a wide range of patient demography (young babies, adults, pregnant women, etc.)
  2. Automated Monitoring System: With the help of a modern detector and monitoring system, it ensures an accurate pressure setting. This integrated detector also supplies real-time data collections that assist medical professionals to track patients’ progress and modify treatment plans.
  3. Telehealth Implementation: Some technical advancements in NIV ventilator mode such as telehealth integration have been an advantage for most healthcare providers to monitor their patient health status remotely.

Non-Invasive Ventilation Patient’s Outcome

The impact of non-invasive ventilation on life has gained remarkable attention and patients with a range of breathing complications have been greatly helped and their health alongside their quality of life have improved. Below are some patient outcomes of non-invasive ventilation:

  1. Enhanced Respirational Ability: Oftentimes, patients with respiratory complications after being placed on NIV positive pressure ventilation, usually have an improved ability to respire. Appropriate amounts of oxygen have been obtained and various breathing complications are lessened.
  2. Reduction in Death Rate: According to studies, the impact of these modes of ventilation on life has caused a considerable reduction in mortality rate. Most cases like COPD can be managed leading to auspicious survival results: an effect orchestrated by non-invasive ventilation initiation. 
  3. Decreased Rates of Intubation: The use of positive pressure ventilation can help avoid or reduce the requirement for invasive ventilation mechanisms. Patients who avoid intubation face fewer of the risks that come with invasive procedures.
  4. Improved Comfort and Adherence of Patients: Non-invasive ventilation (NIV) offers a higher degree of patient comfort. It Improves patient compliance with recommended therapies and serves as a direct result of increased comfort, which guarantees long-term therapy advantages.

    Clinical Advantages of NIV over Invasive Ventilation

    Clinically and technically, Non-invasive ventilation has an edge over invasive ventilation. It possesses a lot of features that are of great remark. The advantages of non-invasive ventilation are beyond measures in the medical application and we have some as follows:

    • Reduce cost: When considering extended hospital stays and the requirement for critical care services, NIV is frequently linked to decreased healthcare expenditures compared to invasive ventilation.
    • Decreased Infection Risk: By doing away with intrusive procedures like intubation, Non-invasive ventilation lowers the risk of pneumonia and other ventilator-associated illnesses.
    • Reduction in Barotrauma Risk: The risk of barotrauma, in which high pressure damages the lungs, exists with invasive respiration. However, diminished pressure settings in NIV lessen this danger and diminish the possibility of lung damage brought on by the ventilator.
    • Promotes Oral Health and Communication: Compared to patients with endotracheal tubes, patients under NIV have greater ease of communication, eating, and oral hygiene, which improves patient wellness and overall quality of life.
    • Use at home is possible: You can use the NIV mode of ventilation with no need for airway skills. Its usage requires less medical prowess compared to invasive ventilation.

    Future Trends in Non-Invasive Respiratory Support

    In the medical field, there are a series of expected developments in technological modifications of clinical equipment. One of these devices that has been a major concern is the non-invasive ventilator (NIV). This appliance has been an incredible device linked with improving patient outcomes with its possible future trends. These future trends are said to optimize ventilation settings and improve personalized healthcare, with the integration of exceptional features such as:

    • Algorithm and Artificial Intelligence
    • Portable Design
    • Wearable device format
    • Improved Telehealth System
    • Biocompatible
    • Enhanced User interface etc.

    References