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Respiratory Failure and Mechanical Ventilation: A Quick Overview

Contact Hours: 6

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Contact Hours: 6

This educational activity is credited for 6 contact hours at completion of the activity.

Course Purpose

The purpose of this course is to provide healthcare professionals with a brief overview of the mechanism of action of acute respiratory failure and respiratory mechanics. It also explains the indications, modes, settings, complications, and nursing considerations of non-invasive and invasive mechanical ventilation.

Overview

Acute respiratory failure is a complex and life-threatening condition that requires a comprehensive and effective management strategy to ensure timely intervention, optimize oxygenation, and mitigate the risk of tissue and organ damage. Acute respiratory failure is often treated with the use of non-invasive and invasive mechanical ventilation to improve patient clinical outcomes. This course examines the mechanism of action of acute respiratory failure and respiratory mechanics. It also explains the indications, modes, settings, complications, and nursing considerations of non-invasive and invasive mechanical ventilation.

Course Objectives

Upon completion of this course, the learner will be able to:

  • Define hypoxic (Type 1) and hypercapnic (Type 2) respiratory failure, their causes, common conditions associated with each.
  • Review non-invasive mechanical ventilation (NIV) types and their suggestions for use according to The American Thoracic Society/European Respiratory Journal guidelines.
  • Review invasive mechanical ventilation and its indications for use.
  • Understand the pathophysiology of respiratory mechanics, and how  respiratory mechanics are influenced by mechanical ventilation.
  • Understand the modes, settings, and complication risks associated with mechanical ventilation.

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This activity has been planned and implemented in accordance with the policies of FastCEForLess.com.

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Definitions
AcidosisA condition in which there is excess acid in the body fluids.
Acute Respiratory Distress Syndrome (ARDS)Occurs when fluid accumulates in the tiny air sacs (alveoli) within the lungs. 
Acute Respiratory FailureA condition in which the lungs have a hard time loading the blood with oxygen or removing carbon dioxide.
Alveolar-Capillary MembraneThe gas exchanging region of the lungs.
AlveoliAny of the many tiny air sacs of the lungs which allow for rapid gaseous exchange.  
Arterial Oxygen Tension (PaO2)A critical parameter that reflects the oxygen pressure in arterial blood.
Assisted ModeDelivers a minimum number of preset mandatory breaths by the ventilator, but the patient can also trigger assisted breaths.
AsthmaA long-term disease of the lungs that causes inflammation and narrowing of the airways.
AtelectasisA condition where lungs collapse partially or completely. 
BarotraumaPhysical damage to body tissues caused by a difference in pressure between a gas space inside, or contact with, the body and the surrounding gas or liquid. 
Bilevel Positive Airway Pressure (BiPAP)A mechanical breathing device with a mask that is used to treat sleep apnea and other health conditions.
CapillariesThe smallest blood vessels in the body, connecting the smallest arteries to the smallest veins.
Carbon DioxideA chemical compound with the chemical formula CO2.
Cardiac OutputThe amount of blood the heart pumps in one minute.
Chronic Obstructive Pulmonary Disease (COPD)A chronic inflammatory lung disease that causes obstructed airflow from the lungs.
Continuous Positive Airway Pressure (CPAP)A chronic inflammatory lung disease that causes obstructed airflow from the lungs.
Dynamic HyperinflationA phenomenon that occurs when a new breath begins before the lung has reached the static equilibrium volume. 
Endotracheal IntubationA life-saving procedure that involves inserting a tube into the airway of a person who cannot breathe on their own.
Endotracheal TubeA tube constructed of polyvinyl chloride (PVC) that is placed between the vocal cords through the trachea to provide oxygen to the lungs.
ExhalationThe flow of the breath out of an organism. 
FibrosisA lung disease that occurs when lung tissue becomes damaged and scarred.
Flow RateRate of a fluid passing through a cross sectional area per unit time.
Fraction of Inspired Oxygen (FiO2)An estimation of the oxygen content a person inhales and is thus involved in gas exchange at the alveolar level.
Helmet VentilationTransparent latex-free hood originally designed for the administration of a specific gas concentration in hyperbaric oxygen therapy.
HypercapniaPresence of higher than normal level of carbon dioxide in the blood.
Hypercapnic Respiratory FailureDefined as an increase in arterial carbon dioxide (PaCO2) > 45 mmHg with a pH < 7.35 due to respiratory pump failure and/or increased CO2 production. 
HypotensionA blood pressure reading below the specified limit (90/60 mmHg).
HypoventilationBreathing at an abnormally slow rate, resulting in an increased amount of carbon dioxide in the blood.  
Hypoxemic Respiratory FailureSevere hypoxemia without hypercapnia.
InhalationThe action of inhaling or breathing in.
Inspiratory Flow RateThe maximal flow generated during a forced inspiratory maneuver. 
Inspiratory/Expiratory (I/E) RatioThe ratio of the duration of inspiratory and expiratory phases.
Interstitial EdemaSwelling caused by fluid buildup in the tiny spaces between tissues or organs.
Interstitial Lung DiseaseDescribes a large group of disorders, most of which cause progressive scarring of lung tissue. 
Intrinsic PEEPOccurs when the expiratory time is shorter than the time needed to fully deflate the lungs, preventing the lung and chest wall from reaching an elastic equilibrium point.
Lung ComplianceThe total compliance of both lungs, measuring the extent to which the lungs will expand.
Mechanical VentilationThe medical term for using a machine called a ventilator to provide artificial ventilation fully or partially.
Minute VentilationAlso known as total ventilation, is a measurement of the amount of air that enters the lungs per minute and is calculated as respiratory rate (RR) times tidal volume. 
Nasal MaskA small mask that covers the nose and provides continuous positive airway pressure, often used in conditions like sleep apnea.
Nasal PillowA type of continuous positive airway pressure mask that goes directly into the nostrils.
Non-Invasive Mechanical Ventilation (NIV)Delivery of oxygen (ventilation support) via a face mask and therefore eliminating the need of an endotracheal airway.
Oxygen ToxicityA condition resulting from the harmful effects of breathing molecular oxygen at increased partial pressures.
Partial Pressure Of Carbon Dioxide (PaCO2)The measure of carbon dioxide within arterial or venous blood.
Peak Airway PressureThe pressure that is generated by the ventilator to overcome both airway resistance and alveolar resistance. 
PerfusionThe passage of fluid through the circulatory or lymphatic system to an organ or a tissue, usually referring to the delivery of blood to a capillary bed in tissue. 
Physiological Dead SpaceThe sum of the anatomical dead space and the alveolar dead space.
PneumoniaAn infection of the air sacs in one or both the lungs. Characterized by severe cough with phlegm, fever, chills, and difficulty in breathing.
PneumatocelesThin-walled, air-filled cysts that develop within the lung parenchyma. 
PneumothoraxAn abnormal collection of air in the pleural space between the lung and the chest wall.
Positive End-Expiratory Pressure (PEEP)The alveolar pressure above atmospheric pressure that exists at the end of expiration.
Positive Pressure VentilationThe process of either using a mask or, more commonly, a ventilator to deliver breaths and to decrease the work of breathing in a critically ill patient.
Pulmonary EmbolismA dangerous condition where a blood clot blocks an artery in the lung, reducing oxygen and damaging the organ.
Reactive Oxygen Species (ROS)Highly reactive chemicals formed from diatomic oxygen (O2), water, and hydrogen peroxide. 
Respiratory Rate (RR)The number of breaths a person takes in one minute. 
ShuntA pathological alternate pathway of circulation.
SensitivityWhat determines how much effort (negative pressure) the patient must generate in order to trigger a breath to be delivered. 
SinusitisAn inflammation of the tissue lining the sinuses that can be caused by various factors, such as the common cold, allergies, or fungal infections.
Sleep ApneaA breathing disorder that causes repeated pauses in breathing during sleep.
Tidal Volume (TV)The amount of air that moves in or out of the lungs with each respiratory cycle.
Tracheal StenosisNormal narrowing of the trachea that restricts the ability to breathe normally.
Tracheal-Esophageal FistulaOccurs when there is a defective connection between the trachea and esophagus.
Trigger SensitivityA setting that determines how easy or difficulty it is for a patient to initiate a breath on a ventilator.
VentilationExchange of air between the lungs and the air (ambient or delivered by a ventilator).
Ventilation-Perfusion MismatchMismatched distribution of ventilation and perfusion, with some lung units receiving disproportionately high ventilation and others receiving disproportionately high perfusion.
Ventilator-Associated Lung Injury (VALI)An acute lung injury that develops during mechanical ventilation and is termed ventilator-induced lung injury (VILI) if it can be proven that the mechanical ventilation caused the acute lung injury. 
Ventilator-Associated Pneumonia (VAP)A lung infection that develops in a person who is on a ventilator.
Vocal Cord InjuryOccurs when one or both vocal cords are not able to move. 
Introduction

Acute respiratory failure is a complex and life-threatening condition that requires a comprehensive and effective management strategy to ensure timely intervention, optimize oxygenation, and mitigate the risk of tissue and organ damage. In the United States, pre-pandemic, the incidence of respiratory failure was about 1,275 cases per 100,000 adults. However, during the pandemic, up to 79% of hospitalized patients developed respiratory failure.1 Globally, acute respiratory failure is the most common postoperative pulmonary complication, with studies showing incidences after major surgery up to 23%. Additionally, findings suggest acute respiratory failure increases the length of a patient’s stay in the hospital by 13 to 17 days, and one in five affected patients will succumb from conditions related to acute respiratory failure.2

Mechanical ventilation is a critical intervention in the continuum of care for individuals in acute settings, ultimately safeguarding patients’ respiratory function and promoting positive clinical outcomes. Therefore, it is essential for healthcare providers to understand its various modes, adjustable settings, potential complications, and the nuances of patient management to deliver optimal and individualized care tailored to the specific needs of patients experiencing acute respiratory failure. This course examines the mechanism of action of acute respiratory failure and respiratory mechanics. It also explains the indications, modes, settings, complications, and nursing considerations of non-invasive and invasive mechanical ventilation.

Acute Respiratory Failure Definition

Acute respiratory failure is a medical condition characterized by the sudden and severe inability of the respiratory system to maintain adequate oxygenation of the blood and/or removal of carbon dioxide in previously healthy patients. This failure can result from various underlying causes and may manifest as a life-threatening emergency. There are two primary types of acute respiratory failure: hypoxemic respiratory failure and hypercapnic respiratory failure.3,4

Hypoxemic respiratory failure, also known as Type 1 respiratory failure, occurs when the oxygen levels in the blood (arterial oxygen tension or PaO2) are significantly low, less than 60mmHg with normal or decreased partial pressure of carbon dioxide (PaCO2). There are four main causes of hypoxemic respiratory failure: hypoventilation, ventilation-perfusion mismatch, shunt, and diffusion impairment. In conditions like acute respiratory distress syndrome (ARDS) or pneumonia, the alveolar-capillary membrane, which facilitates the exchange of oxygen and carbon dioxide, becomes compromised. This can be due to inflammation, fluid accumulation, or damage to the membrane, reducing the efficiency of oxygen diffusion into the bloodstream. Also, certain regions of the lungs may receive inadequate ventilation, leading to a mismatch between ventilation and perfusion. Ventilation refers to the air reaching the alveoli, while perfusion is the blood flow to the capillaries. When these are mismatched, oxygenation is impaired.4,5

If blood bypasses ventilated alveoli, it can lead to a shunting effect where the blood does not undergo proper oxygenation in the lungs. Alternatively, conditions involving interstitial edema (accumulation of fluid in the lung tissue), or fibrosis (scarring) can disrupt the normal architecture of the lungs. This interferes with the diffusion of oxygen across the alveolar-capillary membrane. In severe pneumonia or conditions causing lung collapse (atelectasis), the total lung volume available for gas exchange is reduced. This leads to a decreased surface area for oxygen transfer. Widespread inflammation in the lungs can cause alveolar collapse, reducing the number of functional alveoli available for oxygen exchange. In the case of a pulmonary embolism, a blood clot or other material obstructs pulmonary vessels. This impedes blood flow to ventilated regions of the lungs, causing a significant reduction in oxygen exchange.5,6

Hypercapnic respiratory failure, also known as Type 2 respiratory failure, occurs when there is an inability to adequately eliminate carbon dioxide, leading to an increase in arterial carbon dioxide tension (PaCO2). This can result from various factors affecting the respiratory system. Conditions such as drug overdose, central nervous system depression, or neuromuscular injury can diminish the respiratory drive, leading to insufficient effort in breathing. This results in inadequate ventilation and the retention of carbon dioxide. Conditions like chronic obstructive pulmonary disease (COPD) or asthma cause airway narrowing and obstruction. This increases the resistance to airflow, making it harder to exhale and eliminate carbon dioxide. In diseases affecting the neuromuscular system, such as myasthenia gravis or muscular dystrophy, or situations where respiratory muscles are required to work harder for extended periods, such as in severe asthma exacerbations or prolonged respiratory distress, respiratory muscles can weaken, or fatigue may set in. This weakness impairs the ability to ventilate adequately, leading to carbon dioxide retention.4,7

In some lung diseases or conditions like pneumonia, parts of the lung may receive blood without proper ventilation (ventilation-perfusion mismatch). This increases physiological dead space, reducing the efficiency of carbon dioxide elimination. Conditions causing lung fibrosis, such as interstitial lung disease, reduce lung compliance. Reduced lung compliance makes it difficult to expand the lungs during inhalation and expel carbon dioxide during exhalation. Conditions like sepsis, fever, or hypermetabolic states can increase the body’s metabolic rate, leading to an elevated production of carbon dioxide. If the respiratory system cannot match the increased demand for carbon dioxide elimination, hypercapnia can result. Dysfunction of the central respiratory centers in the brain, which normally respond to elevated carbon dioxide levels, can lead to a blunted or inadequate ventilatory response. This dysfunction may also be seen in certain neurological conditions.4,8

Non-invasive Mechanical Ventilation

Non-invasive mechanical ventilation (NIV) refers to the administration of ventilatory support without the need for an artificial airway inserted into the trachea. The American Thoracic Society/European Respiratory Journal guidelines support the use of NIV in patients with acute respiratory distress or failure who can still maintain their airways on their own. Non-invasive ventilation is advantageous as it avoids the need for intubation, reduces the risk of complications associated with invasive ventilation, and allows the patient to participate in oral intake, speech, and other activities.9

Various types of face masks, such as nasal masks, face masks, nasal pillows, and helmet ventilation, are employed for non-invasive ventilation. A nasal mask covers the nose and is secured using straps. It is suitable for patients who can breathe through their noses and is often used for conditions like sleep apnea or acute respiratory failure. A face mask covers both the nose and mouth. It is useful when nasal breathing is not feasible or for patients who are mouth breathers. Nasal pillows are small, soft prongs that fit directly into the nostrils. They are a less intrusive option for patients who find traditional masks uncomfortable. Helmet ventilation can be used to deliver NIV. It covers the entire head, providing a sealed environment for positive pressure ventilation. This method is particularly useful in patients with facial trauma or those who find masks claustrophobic.10

Invasive Mechanical Ventilation

Invasive mechanical ventilation involves the insertion of an artificial airway, typically an endotracheal tube, to provide ventilatory support. This method is employed when non-invasive approaches are insufficient or contraindicated. Invasive mechanical ventilation provides precise control over the respiratory support delivered to the patient. It is commonly used in critical care settings, surgery, or situations where there is a risk of airway compromise. However, it comes with potential complications and requires sedation to ensure patient comfort and prevent discomfort associated with the artificial airway.11-14

The key steps in invasive mechanical ventilation are: 3,4,14

  1. Endotracheal intubation by placing an endotracheal tube through the mouth or nose into the trachea. It is often done under direct visualization using laryngoscopy. The tube is then secured in place to prevent accidental dislodgment.
  2. Connect to the mechanical ventilator. The ventilator delivers positive pressure breaths to support the patient’s respiratory efforts.
  3. Adjust ventilator settings based on the patient’s respiratory needs.
  4. Continuous monitoring, which is essential during invasive mechanical ventilation. This includes assessing oxygenation, ventilation, and other parameters. Arterial blood gas analysis helps in adjusting ventilator settings to maintain optimal oxygen and carbon dioxide levels.

Indications for Mechanical Ventilation

Mechanical ventilation is initiated based on specific indications related to respiratory function and gas exchange. This includes any of the following conditions: 1-4

  • Respiratory Rate > 30/minute. A high respiratory rate may indicate increased breathing work and respiratory distress. Mechanical ventilation can assist in reducing the respiratory rate and improving overall respiratory efficiency.
  • The inability to maintain arterial oxygen saturation > 90% with fractional inspired oxygen (FiO2) > 0.60. When a patient’s oxygen saturation drops below a critical level despite high levels of supplemental oxygen, mechanical ventilation is initiated to provide better control over oxygenation.
  • A pH < 7.25 (acidosis) suggests a disturbance in the body’s acid-base balance, which can compromise various physiological functions. Mechanical ventilation can help improve ventilation and correct acidosis.
  • Partial pressure of carbon dioxide (PaCO2) > 50 mmHg unless chronic and stable. Elevated PaCO2 levels, also known as hypercapnia, may result from respiratory failure or inadequate ventilation. Mechanical ventilation assists in removing carbon dioxide from the body and maintaining appropriate levels.

These criteria are often used as guidelines, but the decision to initiate mechanical ventilation is based on a comprehensive assessment of the patient’s clinical condition, underlying disease process, and response to initial interventions. Additionally, the patient’s overall clinical trajectory, comorbidities, and individualized goals of care play a crucial role in determining the appropriateness of mechanical ventilation. It is important to note that mechanical ventilation is a complex medical intervention. Decisions regarding its initiation and management are typically made by a multidisciplinary team involving physicians, respiratory therapists, and critical care specialists, and nurses. The goal is to provide the necessary support while minimizing complications and ensuring the patient’s overall well-being. 1-4

Respiratory Mechanics

Respiratory mechanics refers to the study of how the respiratory system components, such as the lungs and chest wall, interact to generate airflow. Understanding key parameters in respiratory mechanics is crucial in managing mechanical ventilation and assessing lung function. These parameters include peak airway pressure, resistive pressure, elevated resistive pressure, elastic pressure, elevated elastic pressure, positive end-expiratory pressure (PEEP), and intrinsic PEEP.15,16

Peak airway pressure is the maximum pressure generated in the airways during inspiration. It includes pressure needed to overcome airway resistance and inflate the lungs. Monitoring peak airway pressure helps prevent lung injury and barotrauma, damage caused by changes in pressure. Resistive pressure is the pressure required to overcome airway resistance during inspiration. Elevated resistive pressure may indicate issues with the endotracheal tube, obstructions in the airways, or conditions like bronchospasm. Monitoring this pressure helps identify and address potential issues. Elastic pressure is the force needed to overcome the elastic recoil of the lungs and chest wall. It is associated with the compliance of the respiratory system. Increased elastic pressure is associated with decreased lung compliance, often seen in conditions like acute respiratory distress syndrome (ARDS). It reflects the difficulty in expanding the lungs during inspiration.15

Positive end-expiratory pressure (PEEP) is the positive pressure maintained in the airways at the end of the respiratory cycle, preventing alveolar collapse. Positive end-expiratory pressure improves oxygenation but must be carefully managed to avoid over-distention of the lungs. Intrinsic PEEP, also known as auto-PEEP or breath-stacking, occurs when insufficient time is allowed for complete exhalation before the next breath begins. This leads to an unintentional increase in end-expiratory pressure. It can cause dynamic hyperinflation and compromise cardiac output. Monitoring all these parameters provides valuable insights into the functioning of the respiratory system and guides adjustments in mechanical ventilation settings. Regular assessment helps maintain optimal ventilation, prevent complications, and enhance patient outcomes.15

Modes of Ventilation

Mechanical ventilation offers various modes to support patients with respiratory failure, and the choice of mode depends on the individual’s clinical condition and underlying respiratory pathology. These modes include mandatory mode or assisted mode. In mandatory mode, ventilation enables partial mechanical assistance with a set number of breaths at a fixed tidal volume. While the machine typically triggers the breath, it does allow the patient to trigger a spontaneous breath with the volume determined by the patient’s effort. Assisted mode allows the patient to contribute to minute ventilation, reducing the need for sedation. Assisted control also decreases the risk of barotrauma, improves intrapulmonary gas distribution, and prevents muscle atrophy.16,17

There are three types of assisted or assist-control (A/C) ventilation: volume-cycled, pressure-cycled, and a combination of volume and pressure-cycled. Volume-cycled ventilation delivers a predetermined tidal volume with each breath, providing consistency but variable peak airway pressures. This mode includes volume-control (V/C) ventilation and synchronized intermittent mechanical ventilation (SIMV). Synchronized intermittent mechanical ventilation blends mandatory and spontaneous breaths, thereby allowing some patient-initiated breaths and offering a balance between ventilator support and patient control. These modes are suitable for patients with variable lung compliance as they ensure a set volume of air is delivered with each breath, accommodating changes in lung characteristics and reducing the work of breathing. However, it is not suitable for patients with restrictive lung diseases, as the variable peak airway pressures may lead to barotrauma and worsen lung damage.16-18

Assisted pressure-cycled ventilation maintains constant pressure during each breath while varying volume, limiting peak airway pressure and minimizing barotrauma risk. It includes pressure-controlled ventilation (PCV), pressure support ventilation (PSV), and non-invasive positive pressure ventilation (NIPPV), which uses a tight-fitting face mask, promoting respiratory support without the need for invasive measures. Assisted pressure-cycled ventilation is effective for patients with restrictive lung diseases because it allows for better control of pressure, which is crucial in conditions where lung compliance is consistently low. However, it is not recommended for patients with acute respiratory failure from obstructive lung diseases, such as chronic obstructive pulmonary disease (COPD), where increased airway resistance can result in inadequate tidal volumes and ineffective ventilation. A combination of volume and pressure-cycled modes includes pressure support ventilation (PSV) and synchronized intermittent mechanical ventilation (SIMV). Pressure support ventilation delivers a set pressure to augment patient-initiated breaths, assisting spontaneous breaths. It is useful during weaning, mimicking natural breathing patterns. 16-18

All these modes are tailored using adjustable ventilator settings, each one able to be fine-tuned to provide optimal respiratory support to patients undergoing mechanical ventilation. The respiratory rate, a fundamental parameter, determines the number of breaths delivered per minute, striking a balance between providing adequate ventilation and preventing complications such as barotrauma. Tidal volume, the volume of air delivered with each breath, is meticulously adjusted to ensure optimal oxygenation while avoiding potential harm associated with overdistension. Trigger sensitivity is a critical setting influencing the responsiveness of the ventilator to a patient’s spontaneous breath, allowing for synchronization and patient-ventilator interaction. Flow rate, another adjustable parameter, governs the rate at which the gas is delivered, impacting the inspiratory phase’s dynamics. The waveform, representing the graphical display of pressure, volume, or flow over time, aids clinicians in assessing the effectiveness and synchrony of ventilation. The inspiratory/expiratory (I/E) ratio, determining the duration of inspiration relative to expiration, is fine-tuned to optimize gas exchange and prevent complications such as air trapping. Each of these adjustable ventilator settings requires careful consideration and individualization to meet the specific needs of the patient, reflecting the nuanced nature of respiratory care in the realm of mechanical ventilation.15,16

Continuous positive airway pressure (CPAP) and bilevel positive airway pressure (BiPAP) are specific modes within the pressure-cycled ventilation category. Continuous positive airway pressure maintains a constant positive pressure throughout the respiratory cycle, prevents airway collapse, and is commonly used for conditions like sleep apnea and acute respiratory failure. Bilevel positive airway pressure provides two different pressure levels during the respiratory cycle, assisting inhalation and reducing pressure during exhalation. These modes are often employed in conditions like chronic obstructive pulmonary disease (COPD) exacerbations and congestive heart failure. Indications for CPAP and BiPAP include respiratory distress, hypoxemia, and conditions requiring ventilatory support. Advantages include improved oxygenation, decreased breathing work, and avoidance of intubation in certain cases. However, disadvantages may include patient discomfort, mask-related issues, and the need for patient cooperation. Careful consideration of patient characteristics and clinical context is essential in selecting the most appropriate ventilation mode for optimal outcomes.19,20

Ventilator Settings

Ventilator settings play a crucial role in tailoring mechanical ventilation to meet the specific needs of patients with respiratory failure. These settings include respiratory rate (RR), tidal volume (TV), inspiratory flow rate, sensitivity, fraction of inspired oxygen (FiO2), positive end-expiratory pressure (PEEP), and inspiratory to expiratory (I:E) ratio. The respiratory rate determines the number of breaths delivered per minute. It is adjusted to maintain appropriate minute ventilation and is often influenced by the patient’s respiratory status. Tidal volume represents the volume of air delivered with each breath. It is typically set based on the patient’s ideal body weight and respiratory condition, aiming to provide adequate ventilation without causing lung injury. Inspiratory flow rate, also known as flow rate, regulates the speed at which gas is delivered during inspiration. Controlling inspiratory flow helps optimize gas exchange and minimizes the risk of barotrauma. Sensitivity, also known as trigger sensitivity, refers to the level of effort or inspiratory flow required to initiate a breath. Adjusting sensitivity ensures that the ventilator responds effectively to the patient’s respiratory efforts, enhancing patient-ventilator synchrony. 11,12,15

The fraction of inspired oxygen represents the percentage of oxygen in the inspired air. Fraction of inspired oxygen  is adjusted to maintain adequate oxygenation and is often initiated at a higher level, gradually titrated down as the patient’s condition improves. Positive end-expiratory pressure is positive pressure applied at the end of expiration, preventing alveolar collapse and improving oxygenation. It is adjusted to maintain adequate lung recruitment and oxygenation. The I:E ratio establishes the duration of inspiration compared to expiration during each respiratory cycle. It is crucial for optimizing gas exchange and can be adjusted based on the patient’s condition and  work of breathing.11,12,15

Complications of Mechanical Ventilation

Mechanical ventilation, while a life-saving intervention, can be associated with various complications. These complications can be broadly classified into those related to the endotracheal intubation procedure and those associated with the mechanical ventilation process itself. Endotracheal intubation can result in ventilator-associated pneumonia (VAP), tracheal stenosis, vocal cord injury, tracheal-esophageal or tracheal-vascular fistula, and sinusitis.

Ventilator-associated pneumonia (VAP) is defined as a lung infection that develops after 48 hours of mechanical ventilation and occurs because the artificial airway provides a pathway for bacteria to enter the lower respiratory tract. Ventilator-associated pneumonia holds considerable clinical significance as it is associated with significant morbidity and mortality rates, particularly exacerbating respiratory compromise in critically ill patients. Prompt diagnosis and intervention are imperative to manage this complication effectively.

Tracheal stenosis is characterized by the narrowing of the trachea resulting from the presence of the endotracheal tube. The tube can cause persistent irritation, inflammation, and damage to the tracheal tissues, leading to the formation of scar tissue. The scar tissue may progress to airway obstruction, compromising respiratory function. Patients with tracheal stenosis may experience increased difficulty breathing and may require medical intervention to alleviate the obstruction. Intubation or prolonged intubation procedures can directly stress and damage the vocal cords, leading to vocal cord injury. This type of injury can adversely affect both speech and airway function. Patients who experience vocal cord injury may exhibit changes in their voice, including hoarseness or difficulty speaking. Additionally, the injury can impact the coordination of the vocal cords, potentially leading to respiratory complications.21-23

Tracheal-esophageal or tracheal-vascular fistula refers to abnormal connections between the trachea and either the esophagus or blood vessels. While these occurrences are extremely rare, they have been linked to prolonged intubation, which can irritate and apply pressure to these anatomical structures. Clinically, this complication is a serious concern as it can lead to the passage of air, fluid, or even food between the trachea and adjacent structures, posing risks of respiratory compromise or other vascular complications.

Sinusitis refers to the inflammation of the sinuses, characterized by the irritation and swelling of the sinus lining. In mechanical ventilation, sinusitis may arise due to direct trauma during the intubation procedure or as a consequence of prolonged intubation, leading to compromised sinus drainage. While it may contribute to patient discomfort, sinusitis typically poses a minor concern compared to other more significant complications.24,25

Complications related to mechanical ventilation include pneumothorax and pneumatoceles, oxygen toxicity, hypotension, and ventilator-associated lung injury (VALI). Pneumothorax and pneumatoceles see air in the pleural space and air-filled cavities in the lung tissue, respectively. Positive pressure generated during mechanical ventilation may cause alveolar overdistension, leading to the rupture of alveoli and subsequent escape of air into the pleural space or lung tissue. This can result in respiratory distress for the patient, leading to lung collapse and impaired oxygenation. Both conditions may necessitate intervention, such as chest tube insertion for pneumothorax to evacuate accumulated air or, in severe cases, surgical measures.

Oxygen toxicity refers to lung damage from prolonged exposure to high levels of supplemental oxygen, which forms reactive oxygen species (ROS) that are known to induce inflammation. Oxygen toxicity can cause oxidative stress, impair lung function, and lead to potential long-term damage.26,27

Hypotension, characterized by low blood pressure, can occur as a clinical consequence of positive pressure ventilation, which affects cardiovascular function. Patients with pre-existing cardiovascular conditions or those who may be hemodynamically unstable are more susceptible to experiencing hypotension during ventilation, necessitating careful monitoring and prompt intervention. Ventilator-associated lung injury (VALI) encompasses lung injury associated with mechanical ventilation, which can damage delicate lung tissues. While VALI can potentially exacerbate existing lung damage, compromising respiratory function and impeding recovery, it may be a necessary risk, depending on the patient’s overall condition. Therefore, healthcare professionals must tailor ventilation protocols to each patient’s condition, while considering factors such as lung compliance and underlying respiratory pathology to mitigate the impact of mechanical ventilation on lung tissue and promote optimal patient outcomes.27,28

Nursing Considerations

In cases of respiratory failure and mechanical ventilation, nursing considerations play a crucial role in ensuring comprehensive care and positive patient outcomes. Continuous monitoring is a critical component of nursing care. This involves the vigilant observation of key vital signs such as respiratory rate, heart rate, blood pressure, oxygen and carbon dioxide (CO2) saturation, temperature, neurological changes, and fluids to promptly identify early deviations from baseline, address emerging issues, and prevent acute respiratory failure. Respiratory rate, a fundamental parameter, is continuously assessed to detect signs of distress or the need for adjustments in ventilator settings. Heart rate and blood pressure monitoring ensure early recognition of cardiovascular compromise, especially in the context of potential hemodynamic instability, and prompt response to fluctuations. Continuous monitoring of oxygen saturation provides real-time insights into the patient’s oxygenation status, allowing nurses to maintain it within the target range for adequate tissue oxygenation. Capnography, measuring end-tidal CO2, is particularly crucial for intubated patients, helping identify issues like airway obstruction or respiratory distress. Temperature monitoring assesses for fever or hypothermia and indicators of potential complications. Neurological assessments encompass evaluating consciousness, pupil reactions, and responses to stimuli to detect any neurological changes that may indicate inadequate oxygenation or central nervous system complications. Overall, continuous monitoring ensures a comprehensive understanding of the patient’s physiological status, enabling nurses to detect early signs of deterioration and provide timely, tailored interventions to optimize care.1,3,9,11

Nurses also play a vital role in managing ventilator settings for patients undergoing mechanical ventilation. It is imperative for them to be intimately familiar with the prescribed ventilator parameters and to conduct regular checks to ensure their alignment with the patient’s needs. Monitoring ventilator settings involves assessing parameters such as tidal volume, respiratory rate, sensitivity, inspiratory-to-expiratory (I/E) ratio, inspiratory flow rate, fraction of inspired oxygen (FiO2), and positive end-expiratory pressure (PEEP). Continuous monitoring of these parameters allows nurses to identify any deviations from the desired targets and promptly intervene by adjusting ventilator settings, ensuring optimal respiratory support and preventing complications related to mechanical ventilation. In addition, nurses must be aware of the development of any complications associated with mechanical ventilation. Rigorous adherence to infection control measures is paramount in minimizing the risk of serious issues such as ventilator-associated pneumonia. This involves meticulous attention to hygiene practices, proper maintenance of ventilator equipment, and regular assessment for signs of infection.16,17

During mechanical ventilation, nurses must also regularly assess breath sounds. This assessment is a fundamental component of patient care, aiming to detect any signs of respiratory distress promptly. Nurses listen for specific breath sounds, including wheezing, crackles, or diminished breath sounds, as alterations in these sounds may indicate underlying complications. Wheezing, for instance, could suggest narrowed airways, while crackles may signal the presence of fluid in the lungs. Diminished breath sounds could be indicative of reduced air movement. Early identification of these changes enables nurses to initiate timely interventions and communicate effectively with the healthcare team to address emerging issues. If necessary, nurses are also responsible for implementing effective airway through suctioning as indicated by the patient’s condition. This involves using a sterile technique to minimize the risk of introducing infections into the airway. Timely and appropriate suctioning not only helps prevent airway obstruction but also contributes to the overall respiratory hygiene of the patient. Nurses must be skilled in assessing the need for suctioning, performing the procedure with precision, and monitoring the patient’s response to ensure optimal airway management.21-28

Another aspect of patient care during invasive mechanical ventilation is patient positioning. Nurses should ensure proper positioning to optimize ventilation and prevent potential complications, including pressure ulcers. Regular turning and repositioning of the patient are essential strategies to mitigate the adverse effects associated with prolonged immobility. These maneuvers not only contribute to maintaining skin integrity but also aid in preventing complications such as ventilator-associated pneumonia and atelectasis. Nurses need to be vigilant in assessing the patient’s comfort and the condition of pressure points during positioning, implementing strategies to distribute pressure evenly.21-28

Patient and family education is a critical component of nursing care. Effective communication is crucial for patients undergoing mechanical ventilation, as they may encounter challenges expressing their needs and concerns. Nurses address these communication barriers by employing alternative methods, such as writing notes or using communication boards to facilitate understanding between the healthcare team and the patient. This approach ensures that patients can actively participate in decision-making regarding their care, express discomfort, or convey essential information about their well-being. Nurses should regularly assess the patient’s communication abilities and adapt their strategies accordingly. Nurses should also explain the purpose and necessity of mechanical ventilation to patients’ families. This includes discussing the potential complications associated with the procedure and outlining the overall plan of care. By offering clear and comprehensible information, nurses help alleviate anxiety and foster a better understanding of the treatment process. Empowering patients and their families with knowledge will encourage active participation in the care journey, promoting a collaborative and informed approach to managing the challenges of mechanical ventilation.

Conclusion

Acute respiratory failure is a complex and life-threatening condition that demands comprehensive strategies to prevent and address its underlying mechanisms. Mechanical ventilation emerges as a pivotal intervention when caring for the critically ill patient by safeguarding respiratory function and contributing to positive clinical outcomes. From volume-cycled and pressure-cycled ventilation to SIMV, CPAP and BiPAP, it is critical for healthcare providers to have a clear understanding of the various modes, respiratory mechanics, and adjustable ventilator settings to ensure ventilation is tailored to the needs of their patients.

Given the array of complications associated with mechanical ventilation, it is also important to prioritize vigilant monitoring, meticulous nursing care, and interdisciplinary collaboration. Nurses, respiratory therapists, physicians, and specialists must work together effectively and engage in open communication to refine strategies, address challenges, and optimize patient outcomes. Nursing considerations, in particular, cover a broad spectrum of responsibilities, from regular assessment of key clinical indicators and breath sounds to prioritizing airway clearance and emphasizing appropriate patient positioning.

Ultimately, clear and accessible communication is fundamental in providing a patient-centered approach to preventing acute respiratory failure and caring for those undergoing mechanical ventilation. Through shared insights and timely interventions, healthcare providers can navigate the complexities of respiratory failure and mechanical ventilation, ensuring the highest standards of care and improving the overall patient experience.

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