Test 3 Information
Mechanical Ventilator
A positive or negative pressure breathing device that can maintain ventilation and breathing for a prolonged period
Tracheostomy
A tracheotomy is a surgical procedure in which an opening is made into the trachea. The indwelling tube inserted into the trachea is called a tracheostomy tube. A tracheostomy (the stoma that is the product of the tracheotomy) may be either temporary or permanent A tracheotomy is used to bypass an upper airway obstruction, to allow removal of tracheobronchial secretions, to permit the long-term use of mechanical ventilation, to prevent aspiration of oral or gastric secretions in the unconscious or paralyzed patient (by closing off the trachea from the esophagus), and to replace an endotracheal tube A fenestrated tube, which allows patient to talk, has a small hole in the tubing between the cuff (inside the pt) and the collar that holds the trache in place A double-cuffed tube has two inner cuffs and inflating the two cuffs alternately can help prevent tracheal damage
Candidates for NIPPV
Acute/chronic respiratory failure Acute pulmonary edema COPD Chronic heart failure (CHF) Sleep-related breathing disorder Can be used at home to improve tissue oxygenation and to rest respiratory muscles while pt sleeps End of life Short/long term ventilation but refused intubation
Cardiac Function Changes
Alterations in cardiac output may occur as a result of positive-pressure ventilation. The positive intrathoracic pressure during inspiration compresses the heart and great vessels, thereby reducing venous return and cardiac output. This is usually corrected during exhalation when the positive pressure is off. The patient may have decreased cardiac output and resultant decreased tissue perfusion and oxygenation.
Diagnostic Testing
Arterial blood gases (ABGs): hypoxemia and initially, respiratory alkalosis as a result of tachypnea. Later, respiratory acidosis results Chest x-ray: bilateral fluffy infiltrates Pulmonary function tests SaO2 monitoring Plasma brain natriuretic peptide (BNP): helpful in distinguishing ARDS from cardiogenic pulmonary edema Echocardiography (transthoracic?): used if BNP isn't conclusive Pulmonary artery catheterzation A normal PCWP (pulmonary capillary wedge pressure) is less than 18 mm Hg and helps to distinguish ARDS from left atrial hypertension (where the PCWP would be elevated) Lab work can help determine the triggering event: CBC, BMP, coagulation studies, serum lacate level, blood urine, bronchial cultures, toxicology screen, serum amylase
Nursing management of patients with acute respiratory failure
Assisting with intubation Maintaining mechanical ventilation Assesses the patient's respiratory status by monitoring the level of responsiveness, arterial blood gases, pulse oximetry, and vital signs. In addition, the nurse assesses the entire respiratory system and implements strategies (e.g., turning schedule, mouth care, skin care, range of motion of extremities) to prevent complications
Anticholingergic Bronchodilators
Block cholinergic-induced bronchoconstriction and thereby relax the area
ARDS Recovery Phase
Clinically, the patient is thought to be in the recovery phase if the hypoxemia gradually resolves, the chest x-ray improves, and the lungs become more compliant
Treatment/Care for ARDS
Close monitoring in ICU and frequent assessment oxygen administration, nebulizer therapy, chest physiotherapy, endotracheal intubation or tracheostomy, mechanical ventilation, suctioning, bronchoscopy Positioning is important. Frequent turning improves ventilation, perfusion, and enhances secretion drainage. HOWEVER, there can be a deterioration in oxygenation with changes in position. Oxygenation is sometimes improves in prone position
Most Commonly used Ventilator Modes
Continuous mandatory ventilation (CMV): Provides full ventilatory support by delivering a preset tidal volume and respiratory rate. This mode of ventilation is indicated for patients who are apneic. Assist-control (A/C) ventilation: Similar to CMV in that the ventilator will deliver preset tidal volumes at a preset rate of respirations. However, if the patient initiates a breath between the machine's breaths, the ventilator delivers at the preset volume (assisted breath). Therefore, every breath is the preset volume Intermittent mandatory ventilation (IMV): provides a combination of mechanically assisted breaths and spontaneous breaths. Mechanical breaths are delivered at preset intervals and a preselected tidal volume, regardless of the patient's efforts. Although the patient can increase the respiratory rate by initiating inspiration between ventilator-delivered breaths, these spontaneous breaths are limited to the tidal volume generated by the patient. IMV allows patients to use their own muscles for ventilation to help prevent muscle atrophy. It lowers mean airway pressure, which can assist in preventing barotrauma. However, "fighting the ventilator" or "bucking the ventilator" may be increased. Synchronized intermittent mandatory ventilation (SIMV): Delivers a preset tidal volume and number of breaths per minute. Between ventilator-delivered breaths, the patient can breathe spontaneously with no assistance from the ventilator on those extra breaths. Because the ventilator senses patient breathing efforts and does not initiate a breath in opposition to the patient's efforts, fighting the ventilator is reduced. As the patient's ability to breathe spontaneously increases, the preset number of ventilator breaths is decreased and the patient does more of the work of breathing. Like IMV, SIMV can be used to provide full or partial ventilatory support. Nursing interventions for patients receiving IMV or SIMV include monitoring progress by recording respiratory rate, minute volume, spontaneous and machine-generated tidal volume, FiO2, and arterial blood gas levels. Pressure support ventilation (PSV): Applies a pressure plateau to the airway throughout the patient-triggered inspiration to decrease resistance within the tracheal tube and ventilator tubing. Pressure support is reduced gradually as the patient's strength increases. An SIMV backup rate may be added for extra support. The nurse must closely observe the patient's respiratory rate and tidal volumes on initiation of PSV. It may be necessary to adjust the pressure support to avoid tachypnea or large tidal volumes. Airway pressure release ventilation (APRV): A time-triggered, pressure-limited, time-cycled mode of mechanical ventilation that allows unrestricted, spontaneous breathing throughout the ventilatory cycle. The inflation period is long, and breaths may be initiated spontaneously as well as by the ventilator. APRV allows alveolar gas to be expelled through the lungs' natural recoil. APRV has the important advantages of causing less ventilator-induced lung injury and fewer adverse effects on cardiocirculatory function and being associated with lower need for sedation and neuromuscular blockade
Promoting Effective Airway Clearance
Continuous positive-pressure ventilation increases the production of secretions regardless of the patient's underlying condition. The nurse assesses for the presence of secretions by lung auscultation at least every 2 to 4 hours. Measures to clear the airway of secretions include suctioning, CPT, frequent position changes, and increased mobility as soon as possible. Sputum is not produced continuously or every 1 to 2 hours but as a response to a pathologic condition. Therefore, there is no rationale for routine suctioning of all patients every 1 to 2 hours. Although suctioning is used to aid in the clearance of secretions, it can damage the airway mucosa and impair cilia action. The sigh mechanism on the ventilator may be adjusted to deliver at least 1 to 3 sighs per hour at 1.5 times the tidal volume if the patient is receiving A/C ventilation. Periodic sighs prevent atelectasis and the further retention of secretions. Because of the risk for hyperventilation and trauma to pulmonary tissue from excess ventilator pressure (barotrauma, pneumothorax), the sigh feature is not used frequently. If the SIMV mode is being used, the mandatory ventilations act as sighs because they are of greater volume than the patient's spontaneous breaths.
Reasons for Mechanical Ventilation
Control patient's respirations during surgery/treatment Oxygenate blood when pt's efforts are inadequate Rest respiratory muscles Evidence of respiratory failure or compromised airway Apnea that isn't readily reversible And more Conditions such as thoracic or abdominal surgery, drug overdose, neuromuscular disorders, inhalation injury, COPD, multiple trauma, shock, multisystem failure, and coma may lead to respiratory failure and the need for mechanical ventilation.
High-Frequency Oscillatory Support Ventilators
Deliver very high respiratory rates (180-900 BPM) that are accompanied by very low tidal volumes and high airway pressures Used to open alveoli in situations characterized by closed small airways (such as atelectasis, ARDS) Also thought to protect the lung from pressure injury
Pressure-cycled Ventilators
Delivers a flow of air (inspiration) until it reaches a preset pressure, cycles off, and expiration occurs Major limitation is the volume of air/O2 can vary as the pt's airway indications for mechanical ventilation resistance/compliance changes. So, tidal volume delivered may be inconsistent, possibly compromising ventilation
Chart 21-12 Initial Ventilator Settings
Done in collaboration with manufacturer's instructions, the respiratory therapist, ((and probably HCP)) 1. Set machine to deliver required tidal volume (10-15 mL/kg) 2. Adjust to deliver lowest concentration of O2 required to maintain normal PaO2 (80-100 mm Hg) --Setting tends to be high at first but is gradually reduced based on ABGs 3. Record peak inspiratory pressure 4. Set mode and rate according to HPC's order. Set PEEP and pressure support if ordered 5. Adjust sensitivity so pt can trigger ventilator with minimal effort (usually 2 mm Hg negative inspiratory force) 6. Record minute volume and obtain ABGs to measure CO2 partial pressure (PaCO2), pH, and PaO2 after 20 minutes of continuous ventilation 7. Adjust settings (FiO2 and rate) according to ABG analysis to provide normal values or those set by HCP 8. If there's poor coordination between breathing rhythms of pt and ventilator (fighting/bucking the vent.), assess for hypoxia and manually ventilate on 100% O2 with a resuscitation bag
Adjusting the Ventilator
Done so that the pt is comfortable and breathing with the machine. If it's adjusted appropriately then there is little to no cardiovascular compromise and satisfactory ABGs
Concepts/Modules: Professional behaviors Quality Improvement Infection Oxygenation
Exemplars: Commitment to profession: work ethics Root cause analysis, breach of care Septicemia ARDS
FASTHUG and BANDAIDS
F-eeding A-nalgesia S-edation T-hrombosis prevention H-ead of bed elevation (more than 45 degrees unless prone) U-lcer prevention G-lucose control B-owels addressed daily A-ctivity addressed/increased daily N-ighttime rest D-isability prevention and discharge planning A-ggressive alveolar maintenance I-nfection prevention D-elirium assessment and treatment S-kin and spiritual care
Acute upper airway obstruction may be caused by
Food particles, vomitus, blood clots Enlargement of tissue in the wall of the airway, as in epiglottitis, obstructive sleep apnea, laryngeal edema, laryngeal carcinoma, or peritonsillar abscess Thick secretions Pressure on airway walls, as occurs in retrosternal goiter, enlarged mediastinal lymph nodes, hematoma around the upper airway, and thoracic aneurysm
Complications Related to Cuff Pressure
High: Tracheal bleeding Ischemia Pressure necrosis Low: Risk for aspiration pneumonia Routine deflation isn't recommended because there's an increased risk of aspiration and hypoxia
Treatment for PEEP caused Hypovolemia
Hypovolemia must be carefully treated without causing further overload. Inotropic or vasopressor agents may be required. Additional treatments may include: Prone positioning High-frequency oscillatory ventilation Low-dose corticosteroids that are administered within the first 14 days of the onset of manifestations
Spontaneous Removal of Endotracheal Tube
Inadvertent removal of an endotracheal tube can cause laryngeal swelling, hypoxemia, bradycardia, hypotension, and even death.
Positive Pressure Ventilators
Inflate that lungs by exerting pressure on the airway, pushing air in (like a bellows), and forcing the alveoli to expand during inspiration Expiration is passive Endotracheal intubation or tracheostomy is usually necessary Widely used in hospital setting and increasingly used in home settings for pts with primary lung disease
Signs and Symptoms of ARDS
Initially, ARDS closely resembles severe pulmonary edema. Acute phase of ARDS is marked by a rapid onset of severe dyspnea that usually occurs less than 72 hours after the precipitating event Arterial hypoxemia that doesn't respond to supplemental O2 Chest x-ray findings: similar tp cardiogenic pulmonary edema and are visible as bilateral infiltrates that quickly worsen Acute lung injury progresses tp fibrosing alveolitis with persistent, severe hypoxemia Increased alveolar dead space (ventilation to alveoli but poor perfusion) Intercostal retractions and crackles possible Anxious and agitated
Endotracheal intubation
Involves passing an endotracheal tube through the mouth or nose into the trachea Usually passed with the aid of a laryngoscope by specifically trained medical, nursing, or respiratory personnel. Once the tube is inserted, a cuff is inflated to prevent air from leaking around the outer part of the tube in order to minimize the possibility of aspiration and secure the tube Cuff pressure needs to be between 15-20 mm Hg May be used no longer than 14-21 days. Tracheostomy considered to decrease irritation and trauma to tracheal lining, reduce incidence of vocal cord paralysis, and decrease work of breathing
Chart 21-11 Indications for Mechanical Ventilation
Lab Values: PaO2: <55 mm Hg PaCO2: <55 mm Hg pH: <7.32 Vital capacity: <10 mL/kg Negative inspiratory force: <25 cm H2O FEV1: <10 mL/kg Clinical manifestations: Apnea or bradypnea Respiratory distressed with confusion Increased work of breathing not relieved by other interventions Confusion with need for airway protection Circulatory shock
Mucolytic agents
Liquefy secretions Nursing management: Assessment of adequate cough reflex, sputum characteristics, and improvement in incentive spirometry Side effects: Nausea and vomiting Bronchospasm Stomatitis (oral ulcers) Urticaria Rhinorrhea (runny nose)
Humidification
Maintained to help liquefy secretions so that they're more easily removed
Oxygenation Module Readings
Med Surg: pg 596-598 Endotracheal intubation: pg 504-506 Mechanical ventilation: pg 493, 509-520
Noninvasive Positive-Pressure Ventilation (NIPPV)
Method of positive-pressure ventilation that can be given via facemasks, nasal marks, nasal pillow (nasal cannula that seals around the nares to maintain pressure) Eliminates need for endotracheal intubation or tracheostomy and decreases risk of nosocomial infections Most comfortable mode is pressure controlled ventilation with pressure support which eases the work of breathing and enhances gas exchange Ventilator can be set with a minimum backup rate for pts with periods of apnea
Cuff Pressure
Monitored every 6 to 8 hours to maintain the pressure at less than 25 mm Hg (optimal cuff pressure is 15 to 20 mm Hg). The nurse assesses for the presence of a cuff leak at the same time.
Adrenergic Bronchodilators
Mostly inhaled Work by stimulating the beta receptor sites, mimicking the effects of epinephrine in the body Desired effect is smooth muscle relaxation which dilates the constricted bronchial tubes
Pharmacologic Therapy
No specific pharm treatment for ARDS Neuromuscular blocking agents, sedatives, and analgesics may be used to improve patient-ventilator synchronization and help to decrease severe hypoxemia Inhaled nitric oxide (an endogenous vasodilator) may help to reduce ventilation-perfusion mismatch and improve oxygenation Sedatives that may be used are lorazepam (Ativan), midazolam (Versed), dexmedetomidine (Precedex), propofol (Diprivan), and short-acting barbiturates Examples of neuromuscular blocking (paralytic) agents include pancuronium (Pavulon), vecuronium (Norcuron), atracurium (Tracrium), and rocuronium (Zemuron) With paralysis, the patient appears to be unconscious; loses motor function; and cannot breathe, talk, or blink independently. However, the patient retains sensation and is awake and able to hear. The nurse must reassure the patient that the paralysis is a result of the medication and is temporary. Paralysis should be used for the shortest possible time and never without adequate sedation and pain management
Bilevel Positive Airway Pressure (BiPAP)
Offers independent control of inspiratory and expiratory pressures while providing pressure support ventilation (PSV) It delivers two levels of positive airway pressure provided via a nasal or oral mask, nasal pillow, or mouthpiece with a tight seal and a portable ventilator. Each inspiration can be initiated either by the patient or by the machine if it is programmed with a backup rate. The backup rate ensures that the patient receives a set number of breaths per minute. Most often used for patients who require ventilatory assistance at night, such as those with severe COPD or sleep apnea. Tolerance is variable; BiPAP usually is most successful with highly motivated patients.
Nutrition and ARDS
Patients with ARDS require 35 to 45 kcal/kg/day to meet caloric requirements. Enteral feeding is the first consideration; however, parenteral nutrition also may be required
Classification of Ventilators
Positive pressure: --Four types total-- Three types of positive-pressure ventilators are classified by the method of ending the inspiratory phase of respiration: volume cycled, pressure cycled, and high-frequency oscillatory support. The fourth type, noninvasive positive-pressure ventilation (NIPPV), does not require intubation Negative pressure: older modes, rarely used (iron lungs, chest cuirass)
Proportional Assist Ventilation (PAV)
Provides partial ventilatory support in which the ventilator generates pressure in proportion to the patient's inspiratory efforts. With every breath, the ventilator synchronizes with the patient's ventilatory efforts. The more inspiratory pressure the patient generates, the more pressure the ventilator generates, amplifying the patient's inspiratory effort without any specific preselected target pressure or volume. It generally adds "additional muscle" to the patient's effort; the depth and frequency of breaths are controlled by the patient
Continuous Positive Airway Pressure (CPAP)
Provides positive pressure throughout the respiratory cycle Can be used as an adjunct to mechanical ventilation with a cuffed endotracheal tube or tracheostomy tube to open alveoli and can also be used with a leak-proof mask to keep alveoli open and prevent respiratory failure Most effective treatment for obstructive sleep apnea (because the +pressure acts as a splint and keeps upper airway and trachea open during sleep) Pt must be breathing independently
Disadvantages of Endotracheal and Tracheostomy Tubes
Pt discomfort Cough reflex depressed because glottis closure is hindered Secretions are thicker because upper respiratory tract is bypassed (handles warming and humidifying) Swallowing reflexes depressed (glottic, pharyngeal, and laryngeal reflexes) because of prolonged disuse and mechanical trauma Increases risk of aspiration/micro aspiration and ventilator-associated pneumonia (VAP) Ulceration and stricture of larynx or trachea may develop Unintentional or premature removal of the tube is a potentially life-threatening complication of endotracheal intubation. Removal of the tube is a frequent problem in intensive care units (ICUs) and occurs mainly during nursing care or by the patient.
ARDS
Severe inflammatory process that causes diffuse alveolar damage that results in sudden and progressive pulmonary edema, increasing bilateral infiltrates on chest x-ray, hypoxemia unresponsive to oxygen supplementation regardless of the amount of PEEP, and the absence of an elevated left atrial pressure Acute exudative phase: Lasts up to a week Associated with damage to alveolar cells and flooding of alveoli. This inactivates surfactant Proliferative phase: Lasts up to 3 weeks Marked by resolution of Acute phase and initial repair of the lung. May recover fully or move on to third phase Fibrotic phase: Fibrotic tissue replaces normal long structure causing progressive vascular occlusion and pulmonary hypertension Many in this stage require long term support with mechanical ventilation and supplemental O2
Contradictions for NIPPV
Those who have experienced respiratory arrest Serious dsyrhythmias Cognitive impairment Head/facial trauma
Bronchodilators
Used to dilate the bronchioles in those with acute lung injury or COPD Classified as adrenergic or anticholinergic
Positive end-expiratory pressure (PEEP)
Ventilator PEEP support is used to treat ARDS Helps to increase functional residual capacity and reverse alveolar collapse by keeping alveoli open. Improves arterial oxygenation and reduction in the severity of ventilation-perfusion imbalance Goal is a PaO2 (partial pressure arterial oxygen) greater than 60 mm Hg or an O2 sat level of >90% at the lowest possible FiO2 (fraction of inspired oxygen) Using PEEP, a lower FiO2 may be required High levels of PEEP therapy can cause systemic hypotension in ARDS (result of hypovolemia secondary to leakage of fluid into interstitial spaces and depressed cardiac output) PEEP is an unnatural pattern of breathing that feels strange to the pt. They may be anxious and "fight" the ventilator. Problems with the vent can cause anxiety as well: tube blockage by kinking or retained secretions, other acute respiratory problems (e.g., pneumothorax, pain), a sudden decrease in the oxygen level, the level of dyspnea, or ventilator malfunction If the PEEP level cannot be maintained despite the use of sedatives, neuromuscular blocking agents (paralytic agents) may be administered to paralyze the patient
Central Venous Line Bundle
What are the five key elements of the central venous line bundle? • Elevation of the head of the bed (30-45 degrees) • Daily "sedation vacations" and assessment of readiness to extubate • Peptic ulcer disease prophylaxis (with histamine-2 receptor antagonists, such as ranitidine [Zantac]) • Deep venous thrombosis (DVT) prophylaxis • Daily oral care with chlorhexidine (0.12% oral rinses)
Monitoring the Ventilator
When monitoring the ventilator, the nurse notes the following: • Controlling mode (e.g., A/C ventilation, SIMV) • Tidal volume and rate settings (tidal volume is usually set at 6 to 12 mL/kg [ideal body weight]; rate is usually set at 12 to 16 breaths/min) • FiO2 setting • Inspiratory pressure reached and pressure limit (Normal is 15 to 20 cm H2O; this increases if there is increased airway resistance or decreased compliance.) • Sensitivity (A 2-cm H2O inspiratory force should trigger the ventilator.) • Inspiratory-to-expiratory ratio (usually 1:3 [1 second of inspiration to 3 seconds of expiration] or 1:2) • Minute volume (tidal volume × respiratory rate, usually 6 to 8 L/min) • Sigh settings (usually set at 1.5 times the tidal volume and ranging from 1 to 3 per hour), if applicable • Water in the tubing, disconnection or kinking of the tubing • Humidification (humidifier filled with water) and temperature • Alarms (turned on and functioning properly) • PEEP and pressure support level, if applicable (with PEEP usually set at 5 to 15 cm H2O)
Respiratory Care Modalities (Mechanical Ventilation)
airway pressure release ventilation (APRV): mode of mechanical ventilation that allows unrestricted, spontaneous breaths throughout the ventilatory cycle; on inspiration the patient receives a preset level of continuous positive airway pressure, and pressure is periodically released to aid expiration assist-control (A/C) ventilation: mode of mechanical ventilation in which the patient's breathing pattern may trigger the ventilator to deliver a preset tidal volume; in the absence of spontaneous breathing, the machine delivers a controlled breath at a preset minimum rate and tidal volume chest drainage system: the use of a chest tube and closed drainage system to re-expand the lung and to remove excess air, fluid, and blood chest percussion: manually cupping hands over the chest wall and using vibration to mobilize secretions by mechanically dislodging viscous or adherent secretions in the lungs chest physiotherapy (CPT): therapy used to remove bronchial secretions, improve ventilation, and increase the efficiency of the respiratory muscles; types include postural drainage, chest percussion, and vibration continuous mandatory ventilation (CMV): mode of mechanical ventilation in which the ventilator completely controls the patient's ventilation according to preset tidal volumes and respiratory rate; because of problems with synchrony, it is rarely used except in paralyzed or anesthetized patients continuous positive airway pressure (CPAP): positive pressure applied throughout the respiratory cycle to a spontaneously breathing patient to promote alveolar and airway stability; may be administered with endotracheal or tracheostomy tube or by mask endotracheal intubation: insertion of a breathing tube through the nose or mouth into the trachea fraction of inspired oxygen (FiO2): concentration of oxygen delivered (1.0 = 100% oxygen) hypoxemia: decrease in arterial oxygen tension in the blood hypoxia: decrease in oxygen supply to the tissues and cells incentive spirometry: method of deep breathing that provides visual feedback to help the patient inhale deeply and slowly and achieve maximum lung inflation intermittent mandatory ventilation (IMV): mode of mechanical ventilation that provides a combination of mechanically assisted breaths and spontaneous breaths mechanical ventilator: a positive- or negative-pressure breathing device that supports ventilation and oxygenation pneumothorax: partial or complete collapse of the lung due to positive pressure in the pleural space positive end-expiratory pressure (PEEP): positive pressure maintained by the ventilator at the end of exhalation (instead of a normal zero pressure) to increase functional residual capacity and open collapsed alveoli; improves oxygenation with lower fraction of inspired oxygen postural drainage: positioning the patient to allow drainage from all lobes of the lungs and airways pressure support ventilation (PSV): mode of mechanical ventilation in which preset positive pressure is delivered with spontaneous breaths to decrease work of breathing proportional assist ventilation (PAV): mode of mechanical ventilation that provides partial ventilatory support in proportion to the patient's inspiratory efforts; decreases the work of breathing respiratory weaning: process of gradual, systematic withdrawal or removal of ventilator, breathing tube, and oxygen synchronized intermittent mandatory ventilation (SIMV): mode of mechanical ventilation in which the ventilator allows the patient to breathe spontaneously while providing a preset number of breaths to ensure adequate ventilation; ventilated breaths are synchronized with spontaneous breathing thoracotomy: surgical opening into the chest cavity tracheostomy tube: indwelling tube inserted directly into the trachea to assist with ventilation tracheotomy: surgical opening into the trachea vibration: a type of massage administered by quickly tapping the chest with the fingertips or alternating the fingers in a rhythmic manner, or by using a mechanical device to assist in mobilizing lung secretions
Clinical Evidence/Diagnostics Supporting Ventilation
continuous decrease in oxygenation (PaO2), an increase in arterial carbon dioxide levels (PaCO2), and a persistent acidosis (decreased pH); however, if the patient's status appears emergent, then waiting for these laboratory results prior to ensuring these ventilator support measures is imprudent ((not caring/rash))
Normal Arterial Blood Gas Values
pH: 7.35-7.45 PaCO2: 35-45 mm Hg PaO2: 80-95 mm Hg HCO3: 22-26 mEq/L O2 Sat: 95-99% Base Excess/Deficit (BE): +/- 1
Partly Compensated Metabolic Acidosis
pH: <7.35 PaCO2: <35 HCO3: <22
Partly Compensated Respiratory Acidosis
pH: <7.35 PaCO2: >45 HCO3: >26
Acute Respiratory Acidosis
pH: <7.35 PaCO2: >45 HCO3: Normal
Acute Metabolic Acidosis
pH: <7.35 PaCO2: Normal HCO3: <22
Partly Compensated Respiratory Alkalosis
pH: >7.45 PaCO2: <35 HCO3: <22
Acute Respiratory Alkalosis
pH: >7.45 PaCO2: <35 HCO3: Normal
Partly Compensated Metabolic Alkalosis
pH: >7.45 PaCO2: >45 HCO3: >26
Acute Metabolic Alkalosis
pH: >7.45 PaCO2: Normal HCO3: >26
Compensated Metabolic Acidosis
pH: Normal PaCO2: <35 HCO3: <22
Compensated Respiratory Alkalosis
pH: Normal PaCO2: <35 HCO3: <22
Compensated Metabolic Alkalosis
pH: Normal PaCO2: >45 HCO3: >26
Compensated Respiratory Acidosis
pH: Normal PaCO2: >45 HCO3: >26
Potential ARDS Causes
• Aspiration (gastric secretions, drowning, hydrocarbons) • Drug ingestion and overdose • Hematologic disorders (disseminated intravascular coagulopathy, massive transfusions, cardiopulmonary bypass) • Prolonged inhalation of high concentrations of oxygen, smoke, or corrosive substances • Localized infection (bacterial, fungal, viral pneumonia) • Metabolic disorders (pancreatitis, uremia) • Shock (any cause) • Trauma (pulmonary contusion, multiple fractures, head injury) • Major surgery • Fat or air embolism • Sepsis -Excessive use of resuscitation fluids Major cause of death in ARDS is nonpulmonary MODS, often with sepsis. ____Direct____ o GI aspiration o Pneumonia o Chest trauma o Embolism o O2 toxicity o Inhalation of irritant o Near drowning ____Indirect____ o Sepsis o Massive trauma o Pancreatitis o Anaphylaxis o CABG o DIC o Multiple Blood transfusions o Severe head injury o Shock
Potential Complications
• Ventilator problems (increase in peak airway pressure or decrease in pressure or loss of volume) • Alterations in cardiac function • Barotrauma (trauma to the trachea or alveoli secondary to positive pressure) and pneumothorax • Pulmonary infection • Sepsis
