Which action will the nurse take to prevent respiratory failure when caring for an obese patient?

Acute hypoxemic respiratory failure is defined as severe hypoxemia (PaO2 < 60 mmHg) without hypercapnia. It is caused by intrapulmonary shunting of blood with resulting in ventilation-perfusion (V/Q) mismatch due to airspace filling or collapse (eg, cardiogenic or non-cardiogenic pulmonary edema, pneumonia, pulmonary hemorrhage) or possibly airway disease (eg, sometimes asthma, COPD); or by intracardiac shunting of blood from the right- to the left-sided circulation. Findings include dyspnea and tachypnea. Diagnosis is by arterial blood gas measurement and chest x-ray. Treatment usually requires mechanical ventilation.

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Symptoms and Signs of AHRF
What assessment finding would the nurse identify in a patient experiencing respiratory failure?
Which action should the nurse start to reduce the risk for ventilator associated pneumonia quizlet?
Which therapy would the nurse incorporate into the plan of care for a patient with acute respiratory distress syndrome?

Airspace filling in acute hypoxemic respiratory failure (AHRF) may result from

Increased alveolar capillary permeability, as occurs in any of the conditions predisposing to acute respiratory distress syndrome (ARDS)

ARDS is divided into 3 categories of severity: mild, moderate, and severe based on oxygenation defects and clinical criteria (see table Berlin Definition of ARDS Berlin Definition of ARDS

). The mild category corresponds to the previous category termed acute lung injury (ALI).

In ARDS, pulmonary or systemic inflammation leads to release of cytokines and other proinflammatory molecules. The cytokines activate alveolar macrophages and recruit neutrophils to the lungs, which in turn release leukotrienes, oxidants, platelet-activating factor, and proteases. These substances damage capillary endothelium and alveolar epithelium, disrupting the barriers between capillaries and airspaces. Edema fluid, protein, and cellular debris flood the airspaces and interstitium, causing disruption of surfactant, airspace collapse, ventilation-perfusion mismatch, shunting, and pulmonary hypertension Pulmonary Hypertension Pulmonary hypertension is increased pressure in the pulmonary circulation. It has many secondary causes; some cases are idiopathic. In pulmonary hypertension, pulmonary vessels may become constricted... read more . The airspace collapse more commonly occurs in dependent lung zones. This early phase of ARDS is termed exudative. Later, there is proliferation of alveolar epithelium and fibrosis, constituting the fibro-proliferative phase.

Causes of ARDS may involve direct or indirect lung injury.

Common causes of direct lung injury are

Acid aspiration

Less common causes of direct lung injury are

Common causes of indirect lung injury include

Trauma with prolonged hypovolemic shock

Less common causes of indirect lung injury include

Drug overdose (eg, aspirin, cocaine, opioids, phenothiazines, tricyclics)
Cardiopulmonary bypass
Neurogenic pulmonary edema due to stroke, seizure, head trauma, anoxia
Radiographic contrast (rare)

Symptoms and Signs of AHRF

Chest x-ray and arterial blood gas (ABG) measurement
Clinical definition (see table )

Hypoxemia is usually first recognized using pulse oximetry. Patients with low oxygen saturation should have a chest x-ray and ABGs and be treated with supplemental oxygen while awaiting test results.

If supplemental oxygen does not improve the oxygen saturation to > 90%, right-to-left shunting of blood should be suspected. An obvious alveolar infiltrate on chest x-ray implicates alveolar flooding as the cause, rather than an intracardiac shunt. However, at the onset of illness, hypoxemia can occur before changes are seen on x-ray.

Once AHRF is diagnosed, the cause must be determined, considering both pulmonary and extrapulmonary causes. Sometimes a known ongoing disorder (eg, acute myocardial infarction Acute Myocardial Infarction (MI) Acute myocardial infarction is myocardial necrosis resulting from acute obstruction of a coronary artery. Symptoms include chest discomfort with or without dyspnea, nausea, and/or diaphoresis... read more

, pancreatitis Overview of Pancreatitis Pancreatitis is classified as either acute or chronic. Acute pancreatitis is inflammation that resolves both clinically and histologically. Chronic pancreatitis is characterized by histologic... read more , sepsis Sepsis and Septic Shock Sepsis is a clinical syndrome of life-threatening organ dysfunction caused by a dysregulated response to infection. In septic shock, there is critical reduction in tissue perfusion; acute failure... read more ) is an obvious cause. In other cases, history is suggestive; pneumonia Overview of Pneumonia Pneumonia is acute inflammation of the lungs caused by infection. Initial diagnosis is usually based on chest x-ray and clinical findings. Causes, symptoms, treatment, preventive measures, and... read more is suspected in an immunocompromised patient, and alveolar hemorrhage is suspected after bone marrow transplantation or in a patient with a connective tissue disease. Frequently, however, critically ill patients have received a large volume of IV fluids for resuscitation, and high-pressure AHRF (eg, caused by ventricular failure or fluid overload) resulting from treatment must be distinguished from an underlying low-pressure AHRF (eg, caused by sepsis or pneumonia).

When ARDS is diagnosed but the cause is not obvious (eg, trauma, sepsis, severe pulmonary infection, pancreatitis), a review of drugs and recent diagnostic tests, procedures, and treatments may suggest an unrecognized cause, such as use of a radiographic contrast agent, air embolism Air embolism Nonthrombotic sources of pulmonary embolism include air, fat, amniotic fluid, infected material, foreign bodies, and tumors. Pulmonary embolism (PE) can arise from nonthrombotic sources. PE... read more , or transfusion Transfusion-related acute lung injury (TRALI) The most common complications of transfusion are Febrile nonhemolytic reactions Chill-rigor reactions The most serious complications, which have very high mortality rates, are Acute hemolytic... read more . When no predisposing cause can be uncovered, some experts recommend doing bronchoscopy with bronchoalveolar lavage to exclude alveolar hemorrhage and eosinophilic pneumonia Overview of Eosinophilic Pulmonary Diseases Eosinophilic pulmonary diseases are a heterogeneous group of disorders characterized by the accumulation of eosinophils in alveolar spaces, the interstitium, or both. Peripheral blood eosinophilia... read more and, if this procedure is not revealing, a lung biopsy to exclude other disorders (eg, hypersensitivity pneumonitis Hypersensitivity Pneumonitis Hypersensitivity pneumonitis is a syndrome of cough, dyspnea, and fatigue caused by sensitization and subsequent hypersensitivity to environmental (frequently occupational or domestic) antigens... read more

, acute interstitial pneumonitis).

Prognosis is highly variable and depends on a variety of factors, including etiology of respiratory failure, severity of disease, age, and chronic health status. Overall, mortality in ARDS was very high (40 to 60%) but has declined in recent years to 25 to 40%, probably because of improvements in mechanical ventilation and in treatment of sepsis. However, mortality remains very high (> 40%) for patients with severe ARDS (ie, those with a PaO2:FIO2 < 100 mm Hg). Most often, death is not caused by respiratory dysfunction but by sepsis and multiorgan failure. Persistence of neutrophils and high cytokine levels in bronchoalveolar lavage fluid predict a poor prognosis. Mortality otherwise increases with age, presence of sepsis, and severity of preexisting organ insufficiency or coexisting organ dysfunction.

Pulmonary function returns to close to normal in 6 to 12 months in most ARDS patients who survive; however, patients with a protracted clinical course or severe disease may have residual pulmonary symptoms, and many have persistent neuromuscular weakness.

Noninvasive oxygenation support
Mechanical ventilation if oxygen saturation is < 90% on high-flow oxygen

If noninvasive oxygenation support does not result in oxygen saturation > 90%, mechanical ventilation probably should be considered. Specific management varies by underlying condition.

Pressure support ventilation can also be used (with similar levels of PEEP). The initial inspiratory airway pressure delivered should be sufficient to fully rest the respiratory muscles as judged by subjective patient assessment, respiratory rate, and accessory muscle use. Typically, a pressure support level of 10 to 20 cm H2O over PEEP is required.

Nearly all patients with ARDS require mechanical ventilation, which, in addition to improving oxygenation, reduces oxygen demand by resting respiratory muscles. Targets include

Plateau alveolar pressures 30 cm H2O (factors that potentially decrease chest wall and abdominal compliance considered)
Tidal volume 6 mL/kg ideal body weight to minimize further lung injury
FIO2 as low as is allowed to maintain adequate oxygen saturation to minimize possible oxygen toxicity

PEEP Ventilator settings should be high enough to maintain open alveoli and minimize FIO2 until a plateau pressure of 28 to 30 cm H2O is reached. Patients with moderate to severe ARDS are the most likely to have mortality reduced by use of higher PEEP.

NIPPV Noninvasive positive pressure ventilation (NIPPV) is occasionally useful with ARDS. However, compared with treatment of cardiogenic pulmonary edema, higher levels of support for a longer duration are often required, and EPAP of 8 to 12 cm H2O is often necessary to maintain adequate oxygenation. Achieving this expiratory pressure requires inspiratory pressures > 18 to 20 cm H2O, which are poorly tolerated; maintaining an adequate seal becomes difficult, the mask becomes more uncomfortable, and skin necrosis and gastric insufflation may occur. Also, NIPPV-treated patients who subsequently need intubation have generally progressed to a more advanced condition than if they had been intubated earlier; thus, critical desaturation is possible at the time of intubation. Intensive monitoring and careful selection of patients for NIPPV are required.

Conventional mechanical ventilation in ARDS previously focused on normalizing arterial blood gas values. It is clear that ventilating with lower tidal volumes reduces mortality. Accordingly, in most patients, tidal volume should be set at 6 mL/kg ideal body weight (see sidebar Initial Ventilator Management in ARDS Initial Ventilator Management in ARDS

). This setting necessitates an increase in respiratory rate, even up to 35/minute, to produce sufficient alveolar ventilation to allow for adequate carbon dioxide removal. On occasion, however, respiratory acidosis Respiratory Acidosis Respiratory acidosis is primary increase in carbon dioxide partial pressure (Pco2) with or without compensatory increase in bicarbonate (HCO3−); pH is usually low but may be near... read more develops, some degree of which is accepted for the greater good of limiting ventilator-associated lung injury and is generally well tolerated, particularly when pH is ≥ 7.15. If pH drops below 7.15, bicarbonate infusion or tromethamine may be helpful. Similarly, oxygen saturation below "normal" levels may be accepted; target saturation of 88 to 95% limits exposure to excessive toxic levels of FiO2 and still has survival benefit.

Because hypercapnia or low tidal volume alone may cause dyspnea and cause the patient to breathe in a fashion that is not coordinated with the ventilator, analgesics (fentanyl or morphine) and sedatives (eg, propofol initiated at 5 mcg/kg/minute and increasing to effect up to 50 mcg/kg/minute; because of the risk of hypertriglyceridemia, triglyceride levels should be checked every 48 hours) may be needed. Sedation is preferred to neuromuscular blockade because blockade still requires sedation and may cause residual weakness.

PEEP Ventilator settings improves oxygenation in ARDS by increasing the volume of aerated lung through alveolar recruitment, permitting the use of a lower FIO2. The optimal level of PEEP and the way to identify it have been debated. Routine use of recruitment maneuvers (eg, titration of PEEP to maximal pressure of 35 to 40 cm H2O and held for 1 minute) followed by decremental PEEP titration was found to be associated with an increased 28-day mortality (5 Treatment references Acute hypoxemic respiratory failure is defined as severe hypoxemia (PaO2 (See also Overview of Mechanical Ventilation.) Airspace filling in acute hypoxemic respiratory failure (AHRF) may result... read more

). Therefore, many clinicians simply use the least amount of PEEP that results in an adequate arterial oxygen saturation on a nontoxic FIO2. In most patients, this level is a PEEP of 8 to 15 cm H2O, although, occasionally, patients with severe ARDS require levels > 20 cm H2O. In these cases, close attention must be paid to other means of optimizing oxygen delivery and minimizing oxygen consumption.

Some investigators believe pressure control ventilation protects the lungs better, but supportive data are lacking, and it is the peak pressure rather than the plateau pressure that is being controlled. With pressure control ventilation, because the tidal volume will vary as the patient's lung compliance evolves, it is necessary to continually monitor the tidal volume and adjust the inspiratory pressure to ensure that the patient is not receiving too high or too low a tidal volume.

Optimal fluid management in patients with ARDS balances the requirement for an adequate circulating volume to preserve end-organ perfusion with the goal of lowering preload and thereby limiting transudation of fluid in the lungs. A large multicenter trial has shown that a conservative approach to fluid management, in which less fluid is given, shortens the duration of mechanical ventilation and length of stay in the intensive care unit when compared with a more liberal strategy. However, there was no difference in survival between the 2 approaches, and use of a pulmonary artery catheter also did not improve outcome (8 Treatment references Acute hypoxemic respiratory failure is defined as severe hypoxemia (PaO2 (See also Overview of Mechanical Ventilation.) Airspace filling in acute hypoxemic respiratory failure (AHRF) may result... read more

). Patients not in shock Shock Shock is a state of organ hypoperfusion with resultant cellular dysfunction and death. Mechanisms may involve decreased circulating volume, decreased cardiac output, and vasodilation, sometimes... read more are candidates for such an approach but should be monitored closely for evidence of decreased end-organ perfusion, such as hypotension, oliguria, thready pulses, or cool extremities.

A definitive pharmacologic treatment for ARDS that reduces morbidity and mortality remains elusive. Inhaled nitric oxide, surfactant replacement, activated protein C (drotrecogin alfa), and many other agents directed at modulating the inflammatory response have been studied and found not to reduce morbidity or mortality. Some small studies suggest that systemic corticosteroids may be beneficial in late-stage (fibroproliferative) ARDS, but a larger, prospective, randomized trial found no reduction in mortality. A recent unblinded clinical trial of dexamethasone administered early in moderate to severe ARDS suggested improvements in ventilator free days and mortality, but the trial was stopped early due to slow enrollment, which may magnify the treatment effects (9 Treatment references Acute hypoxemic respiratory failure is defined as severe hypoxemia (PaO2 (See also Overview of Mechanical Ventilation.) Airspace filling in acute hypoxemic respiratory failure (AHRF) may result... read more

). Thus the role of corticosteroids in ARDS remains uncertain and more data are needed.

1. Frat JP, Thille AW, Mercat A, et al: High-flow oxygen through nasal cannula in acute hypoxemic respiratory failure. N Engl J Med 372:2185–2196, 2015. doi: 10.1056/NEJMoa1503326
2. Patel BK, Wolfe KS, Pohlman AS, et al: Effect of noninvasive ventilation delivered by helmet vs face mask on the rate of endotracheal intubation in patients with acute respiratory distress syndrome: A randomized clinical trial. J AMA 315(22):2435–2441, 2016. doi: 10.1001/jama.2016.6338
3. Grieco DL, Menga LS, Cesarano M, et al: Effect of helmet noninvasive ventilation vs high-flow nasal oxygen on days free of respiratory support in patients With COVID-19 and moderate to severe hypoxemic respiratory failure: The HENIVOT randomized clinical trial. JAMA 325(17):1731–1743, 2021. doi: 10.1001/jama.2021.4682
4. Bellani G, Laffey JG, Pham T, et al: Noninvasive ventilation of patients with acute respiratory distress syndrome. Insights from the LUNG SAFE study. Am J Respir Crit Care Med 195(1):67–77, 2017. doi: 10.1164/rccm.201606-1306OC
6. Guérin C, Reignier J, Richard JC, et al: Prone positioning in severe acute respiratory distress syndrome. N Engl J Med 368(23):2159–2168, 2013. doi: 10.1056/NEJMoa1214103
7. Scholten EL, Beitler JR, Prisk GK, et al: Treatment of ARDS with prone positioning. Chest 151:215–224, 2017. doi: 10.1016/j.chest.2016.06.032. Epub 2016 Jul 8
9. Villar J, Ferrando C, Martinez D, et al: Dexamethasone treatment for the acute respiratory distress syndrome: a multicentre, randomised controlled trial. Lancet Respir Med 8: 267–276, 2020. doi: 10.1016/S2213-2600(19)30417-5

Click here for Patient Education

What assessment finding would the nurse identify in a patient experiencing respiratory failure?

Clinical indicators of acute respiratory failure include: partial pressure of arterial oxygen (Pao₂) below 60 mm Hg, or arterial oxygen saturation as measured by pulse oximetry (Spo₂) below 91% on room air. Paco₂ above 50 mm Hg and pH below 7.35.

Which action should the nurse start to reduce the risk for ventilator associated pneumonia quizlet?

To decrease the risk for ventilator-associated pneumonia, which action will the nurse include in the plan of care? Elevate head of bed to 30 to 45 degrees. A patient with acute respiratory distress syndrome (ARDS) who is intubated and receiving mechanical ventilation develops a right pneumothorax.

Which therapy would the nurse incorporate into the plan of care for a patient with acute respiratory distress syndrome?

The most common treatment for ARDS is oxygen therapy. This involves delivering extra oxygen to patients, through a mask, nasal cannula (two small tubes that enter the nose), or a tube inserted directly into the windpipe.

Which action will the nurse take to prevent respiratory failure when caring for an obese patient?

Symptoms and Signs of AHRF

What assessment finding would the nurse identify in a patient experiencing respiratory failure?

Which action should the nurse start to reduce the risk for ventilator associated pneumonia quizlet?

Which therapy would the nurse incorporate into the plan of care for a patient with acute respiratory distress syndrome?

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