Respiratory_management_and_mechanical_ventilation

Chapter 19: Respiratory Management and Mechanical Ventilation

Introduction

Oxygen is a tasteless, colorless gas that makes up approximately 21% of atmospheric air. It plays a vital role in cellular oxygenation necessary for metabolic processes within the body. Oxygen therapy is essential in treating various acute and chronic respiratory conditions, such as COPD, pneumonia, and acute respiratory distress syndrome (ARDS). The primary goal of oxygen therapy is to maintain arterial oxygen saturation (SaO2) levels between 95% and 100% using the minimal amount of oxygen necessary to avoid complications such as oxygen toxicity. Mechanical ventilation becomes crucial for patients who are unable to breathe spontaneously due to severe respiratory disease, traumatic injuries, surgery-related anesthesia, or certain neurological conditions.

Oxygen Delivery Devices

Supplemental Oxygen

Oxygen delivery systems are primarily determined by the fraction of inspired oxygen (FiO2) required by the patient. Continuous monitoring of vital signs and SaO2 is essential during oxygen therapy to assess patient needs and prevent complications.

Low-Flow Oxygen Delivery Systems

Nasal Cannula

• Description: Comprises tubing with two prongs that are inserted into the nares (nostrils).

• FiO2: Provides 24% to 44% oxygen at flow rates of 2 to 6 liters per minute (L/min).

• Advantages: It is safe, easy to apply, and comfortable for long-term use; allows patients to eat, talk, and ambulate.

• Disadvantages: FiO2 can vary significantly with patient breathing patterns; prolonged use can lead to skin breakdown and drying of mucous membranes.

• Nursing Actions: Regularly assess nares for patency; apply water-soluble gel to prevent dryness; humidify the oxygen if flow rates exceed 4 L/min to reduce irritation.

Simple Face Mask

• Description: A mask that covers both the nose and mouth.

• FiO2: Delivers 40% to 60% oxygen at flow rates of 5 to 10 L/min.

• Advantages: Easy to apply and generally more comfortable than a nasal cannula for many patients.

• Disadvantages: Flow rates below 5 L/min can cause CO2 rebreathing; patients cannot eat or drink while wearing the mask.

• Nursing Actions: Ensure a snug fit to prevent air leaks; encourage switching to a nasal cannula during mealtimes to facilitate eating.

Partial Rebreather Mask

• FiO2: Offers 40% to 70% oxygen at flow rates of 6 to 10 L/min.

• Advantages: This device allows for the rebreathtaking of exhaled air, which is rich in oxygen.

• Disadvantages: It requires careful monitoring to ensure the reservoir bag remains inflated and may cause discomfort for anxious patients.

• Nursing Actions: Keep the reservoir bag sufficiently inflated; monitor the patient’s skin condition and comfort frequently.

Nonrebreather Mask

• FiO2: Provides 80% to 90% oxygen at flow rates of 10 to 15 L/min.

• Advantages: This is the highest concentration of oxygen that can be delivered non-invasively while maintaining the ability to breathe spontaneously; features a one-way valve that prevents room air entry.

• Disadvantages: Requires maintaining mask integrity and may be poorly tolerated by patients who experience anxiety or claustrophobia.

• Nursing Actions: Ensure the reservoir bag is fully inflated before use; frequently check skin integrity under the mask to prevent pressure injuries.

High-Flow Oxygen Delivery Systems

Venturi Mask

• FiO2: Delivers precise oxygen concentration ranging from 24% to 50% at flow rates of 4 to 12 L/min.

• Advantages: Provides precise control of oxygen concentration without the need for additional humidification, thus beneficial in patients with fluctuating respiratory needs.

• Disadvantages: Typically more expensive than standard masks and is also more complex to use.

• Nursing Actions: Regularly assess the accuracy of the flow rates set on the mask and check for kinks or blockages in tubing to ensure adequate oxygen delivery.

Aerosol Mask/Face Tent/Tracheostomy Collar

• FiO2: Can deliver between 30% to 100% oxygen depending on the flow rate, starting at flow rates greater than 10 L/min.

• Advantages: Suitable for patients who cannot tolerate standard masks, often used for those with facial injuries, burns, or for patients with tracheostomies.

• Disadvantages: Because these systems can produce high humidity, they require frequent monitoring of the condensation and humidification aspects to prevent airway obstruction.

• Nursing Actions: Regularly empty condensation from the tubing and ensure the humidification canister is adequately filled.

Oxygen Therapy Indications

• Hypoxemia: Refers to low oxygen levels in the blood, often caused by conditions such as hypoventilation, pulmonary embolism, or low blood volume.

• Hypoxia: Indicates decreased oxygen availability in tissues, which may lead to symptoms such as tachycardia, altered mental status, and visible skin pallor.

Considerations and Client Care

Preparation of the Client

Ensure thorough explanation of procedures to the client while positioning them in a semi-Fowler’s or Fowler’s position, as this promotes better breathing mechanics and improved oxygenation.

Ongoing Care

Provide oxygen therapy at the lowest effective flow rate that achieves desired oxygenation levels. Regularly monitor respiratory rate, rhythm, and effort; assess lung sounds for changes; and check SaO2 levels frequently.Ensure good oral hygiene practices; facilitate lung expansion through methods such as incentivizing spirometry and promoting deep breathing exercises.

Monitoring for Complications

• Oxygen Toxicity: Can result from high concentrations of oxygen over time, potentially leading to symptoms like dry cough, chest pain, and in severe cases, lung damage.

• Respiratory Depression: Vigilance is required for signs of decreased respiratory rate or compromised consciousness; adjust oxygen delivery to maintain appropriate ventilation.

• Position the client to maximize lung ventilation; maintain emotional support to alleviate anxiety associated with oxygen therapy.

• Combustion Risk: Oxygen is a flammable substance; it is imperative to display proper warning signs and educate clients on fire safety practices to reduce the risk of fire hazard associated with the use of oxygen.

Noninvasive Positive Pressure Ventilation

Continuous Positive Airway Pressure (CPAP)

Delivers a constant positive pressure throughout the entire respiratory cycle, effectively aiding patients with obstructive sleep apnea and other conditions requiring airway support.

Bi-level Positive Airway Pressure (BiPAP)

A technique that provides varying pressures for inhalation and exhalation; it is particularly beneficial for patients with chronic obstructive pulmonary disease (COPD) who require additional ventilatory assistance to maintain adequate breathing.

Transtracheal Oxygen Therapy

This approach involves a small, transtracheally placed catheter that minimizes visible skin irritation while delivering oxygen directly to the lungs, improving comfort for long-term oxygen therapy patients.

Endotracheal Intubation

Indications

Emergency airway management is necessary for situations such as acute severe asthma or anaphylaxis. Intubation can either be oral or nasal, depending on the individual patient's needs and conditions.

Nursing Actions

Include securing all necessary equipment before the procedure, vigilant monitoring of vital signs throughout intubation, and confirming correct tube placement with a chest X-ray following the procedure. Assess for bilateral breath sounds and equal symmetric chest movements, critical indicators of proper airway placement.

Mechanical Ventilation

Mechanical ventilation provides vital respiratory support, delivering 100% oxygen and ensuring adequate tidal volume and gas exchange in situations where patients cannot maintain adequate spontaneous ventilation. Common modes of mechanical ventilation include

Mechanical Ventilation Modes

1. Assist-Control (AC)

   • Description: Assist-Control mode is designed to support patients who may not be able to initiate their breaths effectively. In this mode, the ventilator delivers a preset tidal volume for each breath initiated by the patient, ensuring minimum ventilation levels are met. If the patient does not initiate a breath within a set timeframe, the ventilator automatically provides a breath.

   • Indications: This mode is typically used for patients with weak respiratory muscles due to conditions like neuromuscular disorders or in the immediate postoperative period.

   • Benefits: Provides full ventilatory support, can help to prevent fatigue, and allows for patient comfort, where the patient can breathe spontaneously alongside machine-supported breaths.

   • Considerations: Monitor for hyperventilation risk if the patient is anxious and breaths rapidly, which may cause excess ventilatory support.

2. Synchronized Intermittent Mandatory Ventilation (SIMV)

   • Description: SIMV allows for a combination of mandatory and spontaneous breaths. The ventilator delivers a set number of mandatory breaths at a predetermined tidal volume while also allowing the patient to breathe spontaneously, using their own tidal volume if they choose to do so in between the mandatory breaths.

   • Indications: This mode is commonly used for patients who are weaning off mechanical ventilation, as it encourages spontaneous breathing and helps the patient take more control over their ventilation.

   • Benefits: Facilitates the transition from full ventilator support to spontaneous respiration and helps improve respiratory muscle strength. The synchronization with the patient's own breathing pattern minimizes respiratory work during spontaneous breaths.

   • Considerations: Ongoing assessment is necessary to ensure that the patient’s needs are being met during their breaths and that they are not experiencing discomfort or fatigue during the weaning process.

3. Positive End Expiratory Pressure (PEEP)

   • Description: PEEP is a mode used in conjunction with other ventilatory support modes where a predetermined pressure is maintained in the airways at the end of expiration. This prevents complete lung collapse (atelectasis) and improves oxygenation by increasing functional residual capacity (FRC).

   • Indications: It is particularly useful for patients with conditions like ARDS, where improved lung recruitment can be critical for adequate gas exchange.

   • Benefits: Enhances ventilation-perfusion matching, increases overall lung volume, and can reduce the work of breathing for the patient. Additionally, it may help prevent repetitive opening and closing of alveoli, which can lead to further lung injury.

   • Considerations: Excessive PEEP can lead to decreased cardiac output and potential barotrauma; therefore, careful monitoring of hemodynamics and oxygenation response is essential. Adjustments may be required based on the patient's clinical situation and response to treatment.

Complications and Nursing Actions for Mechanical Ventilation Modes:

• Barotrauma and Volutrauma: Monitor for signs of lung overdistension indicating barotrauma and ensure ventilator settings are appropriate to prevent lung injury from excessive volumes.

• Ventilator-Associated Pneumonia (VAP): Implement infection control measures, such as proper oral care, head-of-bed elevation, and regular assessment of the need for continued sedation or neuromuscular blockade to reduce the risk of VAP.

• Patient Comfort: Maintain effective communication with the patient, addressing any discomfort associated with the mechanical ventilation process and ensuring all comfort measures are implemented to support patient wellbeing during therapy. Monitor psychological needs and be prepared to manage anxiety or agitation effectively.

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Complications and Nursing Actions

Monitor for complications such as barotrauma (lung overdistension) and volutrauma (lung injury due to excessive air volume); observe for signs like respiratory distress or decreased urine output, which may indicate complications.Manage risk factors for aspiration by keeping the head of the bed elevated at least 30 to 45 degrees and routinely checking residuals for enteral feeding before administering further feedings.Implement interventions focused on preventing gastrointestinal stress ulcers in at-risk patients, regularly assess lung sounds, and maintain thorough documentation of ventilatory settings and patient responses during mechanical ventilation.