Prone Position in ARDS

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The following course content

This course is an overview of nursing interventions and methods used to care for patients experiencing acute respiratory distress syndrome (ARDS) and how to manage ARDS patients in the prone position. Learners will explore factors that influence ARDS progression, care for the patient in the prone position, and management and intervention options. This course is intended for nurses for all specialties and educational backgrounds. 

Defining Acute Respiratory Distress Syndrome (ARDS)

Acute respiratory distress syndrome (ARDS) was first identified in 1967 during the Vietnam War as a distinctively new subset of hypoxemic respiratory failure. ARDS was first defined in 1994 by the Berlin definition as the acute onset of hypoxemia with bilateral frontal infiltrates on chest radiograph and no evidence of left atrial hypertension. In 1994, the American and European Consensus Conference (AECC) established the specific criteria to describe acute lung injury (ALI) and ARDS. These criteria included acute onset, bilateral lung infiltrates of chest x-ray, no evidence of elevated left atrial pressure, and severe hypoxemia, assessed by the arterial oxygen tension to inspired oxygen fraction (PaO2/FiO2) ratio.

According to the above guidelines, ALI existed at a PaO2/FiO2 of =/< 300mmHg, and ARDS was diagnosed when PaO2/FiO2 =/< 200mmHg. In 2011, the European Society of Intensive Care Medicine proposed the Berlin ARDS definition to replace the AECC definition due to the limitation of diagnostic reliability.

Presently, the Berlin definition of ARDS includes (1-10):

1. An acute onset (within 7 days of new or worsening respiratory symptoms)
2. Bilateral radiographical opacities that are not fully explained by effusion, atelectasis, or masses
3. Arterial hypoxemia defined by thresholds:
   1. Mild: 200 < PaO2/FiO2 ratio ≤300 mm Hg, on continuous positive airway pressure (CPAP) or positive end-expiratory pressure (PEEP) ≥5 cm H2O (observed mortality 27%)
   2. Moderate: 100 < PaO2/FiO2 ratio ≤200 mm Hg, on PEEP ≥5 cm H2O (observed mortality 32%)
   3. Severe: PaO2/FiO2 ratio ≤100 mm Hg, on PEEP ≥5 cm H2O (observed mortality 45%)
4. Identified risk factor for ARDS (if no clear risk factor, exclude heart failure as a cause)
5. Not exclusively due to cardiac causes

After years of extensive research, we know now that ARDS is a complicated emergency clinical condition caused by an inflammatory immune response resulting in endothelium permeability, non-cardiogenic pulmonary edema, and atelectasis. While historically ARDS was formally coined as a health condition within the past few decades, ARDS has existed since the beginning of time, as lung injuries have existed for as long as humans have existed. ARDS is a severe medical complication, that, if left untreated, can lead to permanent organ damage, decreased quality of life, and immediate death. Several ARDS patients receive mechanical ventilation, and ARDS has an extremely high mortality of up to 40% depending on its severity. While ARDS is rarely seen in outpatient settings because of its acute nature, many patients who have survived ARDS are seen in outpatient settings for years.

If patients are lucky and are in general good health, they can survive ARDS with no immediate complications. However, ARDS can affect anyone, from children to elderly, causing nurses to be aware of the role of critical care conditions in the acute and chronic health of patients. Also, as COVID-19 and other respiratory pathogens have emerged within the past decade, ARDS clinical guidelines, care practices, and other interventions have shifted. More research is showing that severe respiratory pathogens, such as COVID-19, SARS, and more, can trigger an ALI and contribute to the development of ARDS, even if previously healthy patients.

What’s more is that, as technology advances, more and more patients are recovering from ARDS, a once near-fatal condition with poor prognosis, and receive outpatient care for their pulmonary health in several outpatient clinics nationwide. In particular, emergency rooms, intensive care units (ICUs), and critical care units can see several patients a day with possible ARDS or at risk of having ARDS. Staffing concerns, documentation issues, and poor provider-patient communication can lead to several cases of ARDS being undocumented, under treated, or poorly managed, leading to decreased quality of life and poorer health outcomes for patients (1-10).

While many clients receive acute care for ARDS within ICUs nationwide, as the demands for home health nursing and medical interventions shift, the reality is that many clients receive follow-up for ARDS complications and ARDS sequalae in non-emergent health care settings daily. Nursing care and patient monitoring must be followed to ensure that patients are receiving appropriate nutrition, maintaining good hydration, tolerating pain management options well, showing respiratory health progression, and showing improvements in health and quality of life. In particular, ARDS management, depending on the severity of ARDS and patient health and response to interventions, is not guaranteed to have the same outcome on every client’s health. Some clients can have more severe ARDS management complications, such as possible lung transplant, lifelong immunocompromise, and worsening of client health status. Because there are several types of pharmacological and non-pharmacological ARDS management interventions, including prone positioning, nurses must be aware of the patient response and health status (1-15).

Prevalence

The exact prevalence of ARDS is not known, as several instances of ARDS are undetected and unreported. While it is estimated that there are thousands of patients with ARDS in America, it is also estimated that ARDS is more prevalent in women and among older people. Studies estimate that the incidence of ARDS is 64.2 to 78.9 cases per 100,000 person-years, and cases of ARDS can be found in several ICU and critical care units nationwide. That said, there are possible cases of ARDS that never make it to emergent care for logistic reasons, costs, and immediate death. Since ARDS is an emergent condition, people can die of ARDS without ever being treated for this condition or have this condition be misdiagnosed or undetected at time of death (1-10).

Signs and Symptoms

Common signs and symptoms of ARDS include loss of consciousness, difficulty breathing, hypoxemia, severe chest pain, muscle weakness, difficulty speaking, and loss of responsiveness. Often times, ARDS has no immediate hallmark signs, as many respiratory conditions can also trigger difficulty with breathing and severe chest pain. That said, ARDS is noted for its hypoxemia, pulmonary edema, worsening of client health condition, and increased workload of breathing. While diagnostic testing and examination can rule out other conditions, ARDS should be a condition to be aware of in all patients with risk factors and respiratory complications given the rapid progression of ARDS (1-5).

Risk Factors

The most common risk factor for ARDS is anything that can cause an ALI, such as blunt force trauma, gunshot wound, motor vehicle accident, infection, blood transfusion, surgery, or other similar situations. For instance, blood transfusions are performed daily in several acute health care facilities. But blood transfusions performed on a geriatric client with a history of pneumonia after surgery makes this client in particular more at risk for developing ARDS. No one develops ARDS from regularly breathing, as ARDS is an acute respiratory emergency. However, anyone is at risk of ARDS if they experience an ALI. It is important to remember that ARDS is triggered by something that causes an ALI. Toxic flume inhalation, substance overdose, septic shock, severe aspiration, ventilation complications, COVID-19, SARS, pneumonia, cardiovascular surgery, organ transplant, pneumothorax, excessive fluid in the lungs, traumatic brain injury (TBI), and pancreatitis are some well-known risk factors for ARDS development.

More studies are showing that patients who are female, elderly, consume alcohol, smoke tobacco, undergo radiation therapy, and who are more exposed to highly respiratory pathogens are at increased risk of ARDS and ARDS complications. Some studies also suggest that ARDS progression and development might have a genetic component, but further research is needed. Furthermore, it is estimated that at least 10-23% of mechanically ventilated patients nationwide meet ARDS criteria. Mortality associated with ARDS is 40-58%, where some studies have shown an approximate decrease in mortality by 50% when prone positioning is used (1-15).

Clinical Criteria for Diagnosis

ARDS is not diagnosed with a single blood test or examination hallmark feature. ARDS also does not have a single cure or treatment option, as prone positioning and other pharmacological and non-pharmacological interventions can slow the progression or severity or ARDS. Also, ARDS can be diagnosed via the Berlin ARDS criteria and is often still viewed as a diagnosis of exclusion. For instance, a patient can be treated in a medical-surgical unit for post-cardiac surgery complications and start to develop early symptoms of what could be ARDS or another post-surgical complication. Because there is no single hallmark feature or diagnostic test for ARDS, the Berlin ARDS criterium remains the gold standard.

That said, while the Berlin ARDS criteria is the main standard for ARDS diagnosis, clinician judgment and patient response consider should guide the need for interventions and prone positioning, as patient response and clinical condition with ARDS can vary widely. Prompt and effective ARDS management is essential, as prolonged or under-treated ARDS can lead to permanent organ damage, severe health complications, and death. Consultations with respiratory therapists, surgeons, critical care nurses, pulmonologists, and other specialists can be considered for ARDS management (1-20).

Pathophysiology Breakdown: The Exudative Phase

Before diving into the benefits of the prone position for ARDS patients, it is important to understand the pathophysiology of ARDS and its implications for ARDS progression, management, and nursing interventions. The pathophysiology of ARDS can be broken down into three main phases: exudative, proliferative, and fibrotic. The cause of the ALI ultimately leading to ARDS can be either indirect or direct, influencing the trajectory and severity of ARDS. In direct cases, the injurious agent, such as a gunshot wound, reaches the lung through the airways or by trauma to the chest. In indirect cases, such as an organ transplant complication, the injurious agent arrives at the lungs through the bloodstream. A direct or indirect agent both can injure the alveolar capillary endothelial cells and type I pneumocytes (alveolar epithelial cells). This leads to a loss of the normally tight alveolar barrier to fluid and macromolecules, causing protein-rich edema fluid to accumulate in the interstitial and alveolar spaces (10-20).

Pro-inflammatory cytokines and lipid mediators are increased in this acute phase, leading to the recruitment of leukocytes, especially neutrophils, into the pulmonary interstitium and alveoli. In addition, condensed plasma proteins aggregate in the air spaces with cellular debris and dysfunctional pulmonary surfactant. This forms hyaline membrane whorls, and alveolar edema predominantly involves dependent portions of the lung with diminished aeration. As edema progresses, there is often a collapse of large sections of dependent lung, which, in turn, contributes to decreased lung compliance and possible lung failure. Consequently, intrapulmonary shunting and hypoxemia develop and the work of breathing increases, leading to dyspnea. All of this is then exacerbated by microvascular occlusion that results in reductions in pulmonary arterial blood flow to ventilated portions of the lung (increased dead space! Hello V/Q mismatch!) and in pulmonary hypertension (10-20).

This means that in addition to severe hypoxemia, hypercapnia, secondary to an increase in pulmonary dead space, can be prominent in early ARDS. The exudative phase is typically the first 7 days of exposure to an ARDS risk factor. Symptoms usually present within 12-36 hours of initial insult, but can be delayed by 5-7 days depending on patient response to ALI, patient compensation factors, and other co-existing health conditions. So, what will a patient look like in this phase? Typically, a patient can appear dyspneic with a sensation of rapid shallow breathing and an inability to get enough air. Tachypnea and increased work of breathing may progress rapidly from mild hypoxemia with a low oxygen requirement to severe hypoxemia with progressively increasing oxygen requirement. A patient can also have associated respiratory fatigue leading to respiratory failure and ultimately a need for mechanical ventilation. An early hallmark clinical sign of ARDS is profound hypoxemia that is resistant to oxygen therapy. Not all patients with ARDS require endotracheal intubation, but it should not be delayed if it is clinically indicated (10-20).

Laboratory values are generally nonspecific and are primarily indicative of underlying clinical disorders or true ARDS severity. The chest x-ray will show infiltrates involving up to 75% of the lung fields but is often indistinguishable from cardiogenic pulmonary edema (CPE). It’s possible to have both CPE and ARDS exist concurrently. It is often safer to assume that there is a component of ARDS and initiate therapies to reduce lung injury rather than ignore early radiographic findings. Both CPE and ARDS may share bilateral airspace opacifications, but ARDS is not typically associated with cardiomegaly or cephalization of the pulmonary vasculature.

When trying to differentiate between CPE and ARDS on a basic chest radiograph, cardiogenic pulmonary edema typically begins centrally, and ARDS will typically present with a uniform opacification. Pleural effusions are more often present in CPE and will respond to diuretic therapy; however, pleural effusions in ARDS will persist despite diuresis. Kerley B lines are a common finding in CPE, whereas they are not typically found in a patient with ARDS. Radiographic and physical exam evidence of cardiogenic pulmonary edema, such as pleural effusions, cardiomegaly, peripheral edema, or clinical heart failure, should be considered in patients with bilateral opacities and respiratory failure (10-20).

Overall, in this phase, the patient looks like that patient whom you’re staring at wondering what’s wrong with them. They are obviously ill, but you just can’t figure out why. Lots of nonspecific findings are present, and the patient looks like there is impending doom.

Pathophysiology Breakdown: The Proliferative Phase

The proliferative phase of ARDS typically occurs between days 7-21 of ARDS progression. Patients tend to improve and are frequently extubated from mechanical ventilation during the proliferative phase. In terms of histology, this is where the nurse will see the first signs of improvement. There is the initiation of lung repair, an organization of alveolar exudates, and a shift from neutrophil dense infiltrates to lymphocyte infiltrates. Despite this, some patients continue to experience dyspnea, tachypnea, and hypoxemia. Some patients will also begin to develop progressive lung injury, which is different from ALI, and begin to show signs of pulmonary fibrosis (10-20).

Pathophysiology Breakdown: The Fibrotic Stage

The majority of patients recover from ARDS within approximately three to four weeks. However, some patients develop a fibrotic stage of ARDS that often includes extended mechanical ventilation needs or noninvasive supplemental oxygen requirements. Low tidal volume and high Positive End-Expiratory Pressure (PEEP) mechanical ventilation along with steroids therapy (when appropriate) may prevent or reduce pulmonary fibrosis. Histologically, the alveolar edema and inflammatory exudates that typically resolve convert to extensive alveolar-duct and interstitial fibrosis. This disruption leads to emphysema-like pulmonary changes. The physiologic consequences of ARDS include an increased risk of pneumothorax, reductions in lung compliance, and increased pulmonary dead space. Patients in this late phase experience a substantial burden of excess morbidity (10-20).

How has ARDS management evolved over the past few decades in your place of work? ARDS develops in three stages. What are the features of each stage clinically, radiographically, and at the alveolar level?

Pharmacological Interventions That Can Alter the Progression of ARDS

As explained previously, the majority of the pathological insult in ARDS occurs within the first seven days during the exudative phase. The evolution of pulmonary and systemic inflammation during the first week will dictate the physiological progression from exudative to fibrosis. Patients who fail to improve in their mechanical ventilation requirements (PEEP and PaO2/FiO2 requirements), static lung compliance, and degree of infiltration on chest x-ray by day 7 of mechanical ventilation exhibit persistently high levels of circulating inflammatory markers. These clients also have a higher mortality rate and are at increased risk of ARDS chronic complications.

Since the direction of systemic inflammatory response is established early in the disease, there have been studies evaluating the effects of early administration of methylprednisolone and the effects on disease trajectory. Some literature suggests that prolonged, low-dose methylprednisolone (1mg/kg/day) within 72 hours of diagnosed ARDS can reduce ARDS progression and ICU stay (10-22). Improvement by day 7 also correlated to survival by day 7 and overall hospital survival. While the use of steroids is not the primary method of treating ARDS, there is growing evidence-based research showing that early and prolonged administration of glucocorticoids can lead to more ventilator-free days and decreased overall mortality by preventing the progression to pulmonary fibrosis. It is encouraged for nurses to investigate and be aware of your particular workplace’s policy regarding ARDS and medication administration policies. Evidence-based research also suggests that steroids may help prevent pulmonary fibrosis if given early, but side effects and medication risk profile are factors to consider in patient care overall (10-22).

Case Study 

You are a nurse working in a busy Medical ICU. You are coming in to start your shift, and you receive the sign out on your patients. There was one admission overnight. A 23-year-old male, Shawn, was brought into the emergency department (ED) from a concert venue with severe alcohol intoxication. He just graduated from college and was celebrating too vivaciously with his family and friends at a local concert. 

Per his mom, he went for a run in the morning and came back to get ready for the tailgate. They started drinking around noon, and Shawn ventured off with some friends later in the afternoon. It wasn’t until several hours later that his family started to worry. Eventually, the family got a call from the local ED that Shawn was in their care. He was found by emergency medical services (EMS) to be highly intoxicated, and he was unable to comply with basic procedures. Shawn was then taken to the hospital for further evaluation. 

In the ER, he was given fluids and basic labs were drawn, including a blood alcohol level and toxicology screen. Labs were all within normal limits. His blood alcohol level was 250 mg/dL. Unfortunately, during his otherwise routine stay, Shawn vomited and aspirated. 

Due to his severe intoxication and mental status impairment, Shawn wasn’t able to protect his airway and required intubation. It was at this point that he was admitted to the medical ICU for further care. Since he’s healthy, the initial nursing care plan is to extubate him early in the day once his sedation wears off and he passes a spontaneous breathing trial (SBT). 

Shawn’s Physical Assessment:  

• Vital Signs: Temperature: 37C tympanic, HR 97 bpm, BP 128/90 mmHg, respiratory rate 25, SpO2 93% on volume control (VC) mechanical ventilation with settings of 60% fraction of inspired oxygen (FIO2), RR 18, PEEP 5, tidal volume (TV) 350. 
• HEENT: Pupils are equal, round and reactive to light bilaterally. Moist mucous membranes. Native teeth intact. Ears intact.  
• Cardiovascular: Heart rate and rhythm regular. No murmurs, rubs or gallops. No peripheral edema. Nail beds pink, capillary refill <2 seconds. 
• Pulmonary: Intubated on VC, appears comfortable, tachypneic above set ventilator rate. No evidence of auto-PEEP. Diffuse crackles and rhonchi in all lung fields. 
• Gastrointestinal: Normoactive bowel sounds. Abdomen is symmetric, soft and nontender to palpation. 
• GU: Foley catheter in place draining yellow urine. 
• Skin: Intact. No rashes, lesions. Normal skin turgor. 
• Neurological: Unable to participate in physical examination due to intubation and sedation. No focal deficits noted. Appropriate response to painful stimuli. 

The nurse practitioner (NP) during your shift asks you to hold his sedation and ask the respiratory therapist to transition him to 40% CPAP once he is awake and able to tolerate an SBT. You arrive, and you realize that your patient is failing his SBT. You want to know if this patient should be re-sedated. You call the NP and tell them about the situation. You explain that the patient is now diaphoretic, tachypneic with a respiratory rate of 40/min, SpO2 of 85%, and tachycardic with a HR 127.  

The NP arrives in a few minutes, and they decide to lightly re-sedate him, switch him back to full ventilation and 100% FiO2 to allow for his Spo2 to recover, and order some diagnostic tests. The NP orders basic lab work, such as a complete blood count (CBC), comprehensive metabolic panel (CMP), lactate levels, coagulation studies, and an arterial blood gas (ABG) level. The NP also orders a portable chest x-ray. 

Diagnosing ARDS – The Berlin Criteria (1-10) 

A diagnosis of ARDS is made when a patient meets the Berlin criteria. The Berlin criteria require that all four of the following are met: 

1. Timing: Symptoms have begun within one week of known clinical insult, or the patient has new or worsening respiratory symptoms over the past week. 
2. Chest Imaging: Bilateral infiltrates consistent with diffuse pulmonary edema must be present on either a chest x-ray or chest CT scan that is not explained by pleural effusions, lobar collapse, lung collapse or pulmonary nodules. 
3. Origin of Edema: Respiratory failure must not be fully explained by cardiac failure or fluid overload. A cardiogenic cause of pulmonary edema had to be excluded by pulmonary artery catheterization showing a pulmonary artery occlusion pressure (PAOP) of <18. Since adopting the Berlin criteria, this has been phased out in favor of using an objective study to rule out hydrostatic pulmonary edema, such as an echocardiogram. 
4. Oxygenation: A moderate to severe impairment of oxygenation must be present- as defined by PaO2/FiO2. There is a direct correlation between the severity of hypoxemia and the severity of ARDS diagnosis: 
5. Mild ARDS: The PaO2/FiO2 ratio is > 200, but ≤ 300, on a ventilator with a PEEP or continuous positive airway pressure ≥ 5 cm H2O. This used to be referred to as acute lung injury- this phrase is now replaced with mild ARDS. 
6. Moderate ARDS: The PaO2/ FiO2 ratio is > 100, but ≤ 200 mmHg, on a ventilator with a PEEP ≥ 5 cm H2O. 
7. Severe ARDS: The PaO2/ FiO2 ratio is ≤ 100 on a ventilator with a PEEP ≥ 5 cm H2O. 

Case Study Continued 

The NP receives the lab results, collaborates with the physician in the ICU, and informs you of the results via the patient portal. Labs appear normal aside from a minor value of leukocytosis of 14,000. 

His ABG is as follows: pH 7.45/CO2 26/ HCO3 22/ PaO2 105 on 100% FiO2. Using these numbers, the patient would have a PaO2/FiO2 of 105 which is compatible with moderate ARDS. In this particular patient, it can be assumed that the inciting incident was the episode of aspiration on stomach contents prior to intubation in the ED. Since ARDS is an inflammatory process set off due to an underlying disease process, the health care team in the ICU decides that the focus is to treat the underlying disease (in this case, aspiration pneumonia/pneumonitis) and support the respiratory system through the ARDS process. 

What Do We Do with the Ventilator in ARDS?

Several evidence-based guidelines can be used to determine ventilator settings and patient management for patients on a ventilator. It is also important to check with your workplace regarding ventilator management and to ensure that you are working within your scope of work to perform care and adjust ventilator settings as appropriate within your nursing scope. The cornerstone of ARDS therapies are low tidal volume and high PEEP mechanical ventilation, and the conservative use of intravenous fluids (when there is no organ dysfunction caused by tissue hypoperfusion) in conjunction with the use of diuretics to hasten mechanical ventilation liberation.

The basics of ventilator guidelines that nurses should be aware of include ventilator setup and adjustment, oxygenation goal, plateau pressure goal, and ventilator weaning. As you move forward and read the guidelines associated with ventilation management in the ARDS patient, you will notice that there is an emphasis on low tidal volume ventilation. As a side effect of this guideline, patients are more likely to become hypercarbic and subsequently acidotic. The purpose of ventilator management is to allow the damaged and inflamed lungs to heal. In order for this to be successful, many health care providers use a “permissive hypercapnia” philosophy. This means that evidence shows it is better to have patients who are hypercapnic and acidotic to an extent than to have a normal blood gas with ventilator settings that damage the lungs. The idea is that in ARDS we must allow the lungs to heal, even if the blood gas is not perfect. The focus of ARDS mechanical ventilation should be focused on optimizing the patient’s ventilation while protecting the lungs, and not driven by perfecting the ABG results (10-29).

Part 1: Ventilator Set-up and Management

The goal of mechanical ventilation in ARDS is to minimize inflammation by reducing barotrauma and volutrauma to the lungs. In ARDS, the lungs are stiff, and each ventilator breath causes alveolar shear. This repeated shearing worsens the inflammation and perpetuates the cycle of increased inflammation and decreased gas exchange across the injured alveoli. By reducing tidal volume and increasing PEEP, the goal is to decrease alveolar shear.

To lessen the opportunity of ventilator-associated lung injury, it is recommended to use a low tidal volume ventilation with high PEEP coupled with a high respiratory rate. As a surrogate of lung stiffness, we use plateau pressure. If the plateau pressure is consistently above 30, this is an indicator that there is excessive stretching the injured, stiff lungs, causing further injury.

Below is the step-wise evidence-based approach to achieve adequate ventilation and oxygenation in the ARDS patient without adding insult to injury. You will notice that some of the calculations rely on the patient’s predicted body weight and other health factors (10-29).

1. Calculate predicted body weight (PBW) Males = 50 + 2.3 [height (inches) – 60] and Females = 45.5 + 2.3 [height (inches) -60]
2. Select any ventilator mode
3. Set ventilator settings to achieve initial VT = 8 ml/kg PBW
4. Reduce VT by 1 ml/kg at intervals ≤ 2 hours until VT = 6ml/kg PBW.
5. Set initial rate to approximate baseline minute ventilation (not > 35bpm).
6. Adjust VT and RR to achieve pH and plateau pressure goals below.

pH Goals and Management

Table 1. pH goals and interventions for ventilator management 

Consider the effect of acidosis rather than the absolute number. Some patients may have hypotension, arrhythmias, skin changes, and other clinical manifestations at a pH of 7.2, while others may tolerate a pH of 7.1 without issues. In general, the approach is one of “permissive acidosis,” meaning acidosis is permitted as much as possible in order to ensure lung-protective ventilation is maximized. 

Inspiration to Expiration Ratio Goals 

Inspiration (I) to expiration (E) ratio goal (I:E): Duration of inspiration should be < duration of expiration. 

Pressure Goals and Management 

Plateau pressure goal: ≤ 30 cm H2O 

• The plateau pressure is the amount of pressure applied to the terminal airways and alveoli. It’s measured by using a 0.5 – 1-second inspiratory pause at end-inspiration, with a goal of <30 cm H2O. When titrating ventilator settings, the increasing PEEP coupled with decreased lung compliance can cause increased plateau pressure, leading to a higher risk of alveoli overdistension and lung injury. The use of tidal volumes >6-8 mL/kg can add to the risk of overdistension and ventilator-associated volumtrauma. 
• Check Pplat (0.5 second inspiratory pause), at least q 4h and after each change in PEEP or VT. 
• If Pplat > 30 cm H2O: decrease VT by 1ml/kg steps (minimum = 4 ml/kg). When the tidal volume begins to decrease, especially if using volumes of 4mL/kg, make sure to check frequent ABGs to avoid complications.  
• If Pplat < 25 cm H2O and VT< 6 ml/kg, increase VT by 1 ml/kg until Pplat > 25 cm H2O or VT = 6 ml/kg. 
• If Pplat < 30 and breath stacking or dys-synchrony occurs: may increase VT in 1ml/kg increments to 7 or 8 ml/kg if Pplat remains < 30 cm H2O. 
• Please note that plateau pressures may be artificially elevated it patients are ventilator asynchronous or breathing against the ventilator.  

Oxygenation Goals and Management 

Oxygenation Goal: PaO2 55-80 mmHg or SpO2 88-95% 

• Use a minimum PEEP of 5 cm H2O. Consider the use of incremental FiO2/PEEP combinations to a max FiO2 of 100% and max PEEP of 24 to achieve goal. 
• The physiologic reason behind using high levels of PEEP is to avoid the repetitive opening and closing of the atelectatic alveoli that can induce or worsen ventilator-induced lung injury. The idea is to keep the alveoli open at end-inspiration and to preserve the inspiratory lung recruitment. 

​Part II: Ventilator Weaning 

Part of weaning clients off the ventilator includes conduct a spontaneous breathing trial daily as tolerated (10-29). Conduct a spontaneous breathing trial (SBT) daily when: 

• FiO2 ≤ 0.40 and PEEP ≤ 8 OR FiO2 < 0.50 and PEEP < 5. 
• PEEP and FiO2 ≤ values of previous day. 
• Patient has acceptable spontaneous breathing efforts. (May decrease vent rate by 50% for 5 minutes to detect effort.) 
• Systolic BP ≥ 90 mmHg without vasopressor support. 
• No neuromuscular blocking agents or blockade. 

If all above criteria are met, and the patient has been stable and responsive for at least 12 hours, initiate a SBT of UP TO 120 minutes of spontaneous breathing with FiO2 < 0.5 and PEEP < 5. Follow these steps:  

1. Place on T-piece, trach collar, or CPAP ≤ 5 cm H2O with PS < 5 
2. Assess for tolerance as below for up to two hours. 
   1. SpO2 ≥ 90: and/or PaO2 ≥ 60 mmHg 
   2. Spontaneous VT ≥ 4 ml/kg PBW 
   3. RR ≤ 35/min 
   4. pH ≥ 7.3 
3. No respiratory distress. Distress = 2 or more of the following: 
   1. HR > 120% of baseline 
   2. Marked accessory muscle use 
   3. Abdominal paradox 
   4. Diaphoresis 
   5. Marked dyspnea 
4. If tolerated for at least 30 minutes, consider extubation. 
5. If not tolerated, resume pre-weaning settings. 

Case Study Continued 

Let’s go back to our case study. Remember, Shawn’s ABG values were: pH 7.45/CO2 26/ HCO3 22/ PaO2 105 on 100% FiO2. The PaO2/FiO2 of 105 is compatible with moderate ARDS. The healthcare team decided to focus on treating the underlying disease (Shawn’s aspiration pneumonia/pneumonitis). Now, using the information from the section above, initially, 8mL/kg PBW would be tidal volume of 658 mL. Since 6mL/kg PBW is also acceptable, it is appropriate to start there. The tidal volume can be set to 493 mL, which is still some pretty big breaths! You select AC as your ventilator mode, set the FiO2 to 100% TV to 490, respiratory rate of 20 to start, and turn the PEEP up to 18. You let Shawn rest for 30 minutes and get your first ABG, which is as follows: pH 7.13, CO2 65, HCO3 25, PaO2 76. 

Based on these results, you consult with the provider on site and are advised to increase the ventilator rate and the PEEP to help with persistent hypoxemia. The provider also orders a follow up ABG, and this pattern will be repeated until the pH is >7.3 or the CO2 is <25. For the next several hours, the nurse follows this protocol, but the patient is remaining acidotic. The nurse notices that his PaO2/FiO2 remains low. The nurse tried several times to titrate the PEEP up in order to bring the FiO2 below 100%, but the client’s SpO2 precipitously drops to the low 80% range each time. The PEEP has been titrated up to 24, and the FiO2 remains at 100%. 

After several ABGs with worsening acidosis, the provider and clinical team decide to initiate chemical paralysis to ensure complete control of his ventilation and respiratory effort. At times, adequate sedation is not enough to overpower the body’s innate respiratory drive. Because of this, chemical paralysis is needed to physically take complete control of the patient’s respiratory effort and work towards correcting the profound acidosis. 

The nurse also initiates a steroid regimen since it is early in the disease process and can help decrease the likelihood of ARDS progressing to the fibrotic stage. Shawn is 190 lbs, and the recommended dose of methylprednisolone in ARDS is 1mg/kg/day. This comes out to 86mg/day, which will be scheduled to start this evening. 

Prone Positioning: What Is It, and Why Are We Doing It?

Prone positioning is a therapeutic modality that has been used to aid in oxygenation in patients diagnosed with ARDS. It involves turning the patient completely over onto their stomach in the face-down position. Prone positioning has been used with success for many years in patients who have developed ARDS. There has been growing evidence-based research confirming that oxygenation is significantly improved in patients who are in the prone position rather than in a supine position, particularly for those patients with ARDS. Prone positioning first came into practice in the 1970s after the introduction of CT scanning. It was observed on CT scans that lung consolidation and edema was primarily in the dependent lung regions with the aerated portion of the lung is in the non-dependent areas.

Although there is an improvement in patient arterial oxygen saturation in the prone position, it is likely due to the homogenous redistribution of alveolar stress in the prone position versus the supine position rather the original hypothesis of better aerating nondependent areas of lung. The mechanisms by which prone positioning may benefit patients with ARDS undergoing mechanical ventilation include improving ventilation–perfusion matching, increasing end-expiratory lung volume, and preventing ventilator-induced lung injury by more uniform distribution of tidal volume through lung recruitment and alterations in chest wall mechanics (30-39).

When to Initiate Prone Positioning 

There is no hard and fast rule as to when to initiate prone therapy. There are patient specific factors that must be considered as well as facility resources. It is a resource-intensive process and requires vigorous monitoring. Evidence-based literature suggests that earlier proning may be better for both short and long-term outcomes. Currently, proning is often used as a last resort, whereas it may have more benefit when used early. Proning a client remains an area of great debate, but there is some strong evidence suggesting that earlier proning may be superior, hence this recommendation.  Clinical practices vary, and an individualized choice has to be made for reach patient. It is also important to remember that low-tidal volume, high PEEP therapy is likely synergistic with proning therapy (30-39). 

How Long and How It’s Done 

There is no standard of time that a patient should remain in the prone position; however, most evidence-based literature states that 12-16 hours a day in the prone position with the remaining 8-12 hours in the supine position shows the most benefit. There is suggested evidence that suggests that if the patient has an improvement in PaO2 >10 mmHg within 30 minutes of being placed in the prone position, as evidenced by ABG results, prone positioning is more likely to show prolonged benefit from prone positioning. Length of therapy is dictated by the patient’s tolerance of the physical repositioning procedure, success in improving the patients PaO2, and whether the patient is able to sustain improvements made in the prone position when transitioned back to supine. While this criterion is not the hard and fast rule for stopping prone positioning, it is the criteria that many intensivists use when caring for the proned ARDS patient.  

Contraindications to prone positioning include those patients with increased or risk of increased intracranial pressure, hemodynamic instability, spinal cord injuries, and recent abdominal surgery (30-39). 

Proning: The Process of Placing a Patient in the Prone Position

It is highly recommended that proper forethought be given prior to proning a patient. Ideally, there will be a formal policy along with education for staff members. Complications of proning can include extubation and severe skin breakdown. These complications are increased when the staff is inexperienced and/or untrained (30-39).

In order to safely prone a patient, there needs to be:

• An adequate number of nurses available to watch lines and safely perform the procedure (likely 3-5)
• A respiratory therapist who is solely responsible for the airway
• A provider experienced in ET intubation immediately available in case of tube dislodgement

It is suggested to stop tube feeding for 2 hours prior to the procedure in order to reduce the risk of aspiration. If the patient is not already, place them on 100% Fi02 for 10-20 minutes in order to provide pre-oxygenation. The first step of the procedure is gathering supplies. The patient will need adequate padding for bony prominences and pressure points, a crash cart, including intubation supplies, eye lubricant, and eye shields. The patient should be paralyzed and adequately sedated prior to the procedure. The patient’s eyes should be lubricated and taped shut. Padding should be placed on the face, chest, pelvis, wrist, and anterior leg region at a minimum (30-39).

The procedure varies slightly. If the staff are using a specialized bed, staff will place the patient on the bed at this point. If using a specialty bed, the major difference is that staff will simply turn the patient using the bed, rather than manually. Prior to actually turning, a nurse should be responsible for each line. Each line (such as central line, arterial lines) should be monitored by a dedicated nurse who is not involved in the turning process. A respiratory therapist should be in charge or monitoring the ET tube and to ensure it is not displaced. A provider skilled in ET intubation should be present to oversee the procedure and monitor vital signs. 8-12” of cushioning (typically 2-3 pillows) should be placed on the chest and hip region. These will support the patient and allow for adequate lung expansion. For the turning process, the nurse will need 2-4 additional staff members to physically turn the patient. This must be done slowly and meticulously to prevent line/tube displacement (30-39).

Once the patient is prone, all lines and tubes as well as patient response should be re-assessed. Patient tolerance should be monitored and noted. An ABG within the next 30-60 minutes is compared to one obtained immediately pre-prone positioning. A reverse Trendelenburg position may be used to reduce aspiration risk. Depending on the habitus, the patient may need a pillow placed under their head for positioning and comfort (30-39).

Case Study Continued

Since no other maneuvers are improving the Shawn’s respiratory status, and chemical paralysis did not drastically improve his status, the clinical team decides the best option is to place him prone. The facility doesn’t have the fancy beds here. The fancy beds can cause facial skin breakdown and take up too much room. The nurse reaches out to another ICU nurse to gather supplies and extra hands to manually reposition the client.

The care team discusses this treatment method with his tearful and scared mother, who agrees to do anything necessary to help her son. Yourself and four experienced ICU nurses prepare Shawn by taping and lubricating his eyes, padding bony prominences (knees, elbows, shoulders, ankles) with soft foam pads, moving cardiac wires to a posterior position to decrease skin breakdown, and retaping his ET to prevent skin breakdown from the plastic holster.

You position yourself at the head of the bed along with a respiratory therapist to watch the airway, while the nurses position Shawn onto his stomach. You watch hemodynamics for changes in his heart rate or blood pressure, and the nurses ensure that all his IV lines and tubes are without kinks.

After 30-45 minutes, another ABG is drawn, which shows the following: pH 7.32/ CO2 50/ HCO3 24/ PaO2 140. Since his PaO2 has improved from 115 to 140, and the client is otherwise stable, the care team decides to leave him in the prone position for the next 12 hours. The provider orders ABGs hourly to start, a chest x-ray timed for when he will be placed supine again, and take a sigh of relief that finally there is some improvement.

Case Study Continued 

After four days of proning Shawn for 12-16 hours a day, his ABGs improved to pH 7.42/ CO2 40/ HCO3 22/ PaO2 95 on 40% FiO2. This still meets criteria for mild ARDS, but the PaO2 stopped improving with prone vs supine positioning. The client remained intubated for an additional two days before being extubated to high flow nasal cannula. 

The client’s first words were “I am never drinking again.” The client was ultimately discharged from the hospital with home physical therapy to help him regain overall strength and endurance. 

Special Considerations for ARDS and Prone Positioning for Pediatric Patients

ARDS and prone positioning are not limited to adult patients. In fact, evidence-based research on infants and children with ARDS and prone positioning is a growing pediatric critical care topic, especially during the COVID-19 pandemic. While ARDS is often diagnosed and seen in adults, anyone can experience an ALI, including children, which can then increase their risk for ARDS. ARDS and proning in this population can pose a serious risk to someone’s quality of life, educational accessibility, ability to care (or learn to care) for one’s self, and more. From toddlers to adolescents, pediatric patients have their own unique set of considerations for ARDS and proning.

For instance, prematurity, burns, physical trauma, gunshots, blood transfusions, nerve damage, and more can affect the pediatric population, causing possible ALIs and an increased risk for ARDS. Also, many health care providers might not screen for ARDS initially in pediatric populations depending on the severity of the ALI. For instance, a toddler experienced a blood transfusion after experiencing a car accident might not be the patient deemed most at risk for an ALI leading to ARDS. Likewise, an adolescent could be involved in a fight, leading to a gunshot wound in the chest, leading to ALI and ARDS risks (1-10, 30-39).

Weight, parental consent, medication dosing, frequency of repositioning, cost, accessibility, and patient and caregiver education are all factors to consider when thinking of proning management options in this population. In addition, proning and ARDS severity can greatly depend on the overall health of the patient, any pre-existing health conditions, and pain severity. While there are several stances and guidelines on ARDS management for pediatric populations, there is still much discrepancy among consistent guidelines and evidence-based research on proning. Educating parents, caregivers, and family members about proning is essential, especially if patients are discharged after and given outpatient follow-up regimens to complete. For instance, a new mother might see her premature infant be in the prone position in the neonatal NICU, and then, upon discharge, she thinks it might be OK to place the baby prone during naptimes. Education on safe sleep and why prone positioning was done in the hospital setting versus not to continue this practice outside of the hospital is essential (1-15,30-39).

Proning in pediatric patients also needs to be monitored very carefully, as children in particular use much smaller sizes of tape, pillows, needle sizes, infusion pumps, and vital sign parameters. Unlike adult populations, children might not be unable to verbalize their pain or comfort levels during medical interventions. Despite this, comfort measures and pain medication can be offered and administered, such as music therapy, talk therapy, parental and caregiver involvement, and other non-pharmacological interventions. Taking the time to educate and inform parents about these interventions is essential. Proning in pediatric patients requires a good eye to detail, clear documentation, and excellent patient care since tubes are smaller (can be misplaced easier), vital signs can change much more rapidly, and caregivers are often much more involved (1-15, 30-39).

Special Considerations for ARDS and Prone Positioning for Geriatric Patients 

The geriatric population is one of the largest growing patient populations in America and is continued to increase with the rise of America’s aging population. In addition, the geriatric population is the most likely to experience severe ARDS complications given their likelihood of having more pre-existing health conditions, skin integrity, and decreased immune system response. Elderly patients have several factors that could contribute to the likelihood of developing ARDS and the need for the use of proning. Because of their decreased skin integrity, possible increased mobility issues, and polypharmacy concerns, pain management during proning and extra care for skin integrity during repositioning is a growing concern in health and among evidence-based research guidelines.  

In fact, there are several inconsistencies in proning for elderly patients at times given clinician judgment, workplace dynamics, patient response to therapy, and caregiver intervention, often leaving providers at their own clinical discretion based on resources and patient situation. For instance, an 86-year-old patient might be admitted for a fall in which they land on their chest, causing a broken rib to be diagnosed in the ER. A few days after discharge, this patient is having increasing chest pain while also consuming alcohol daily for the past twenty years. By the time they have reached the ER again, their work of breath is much more, and they collapse in the ER. By the time this patient makes it to the ICU, there are conflicts about power of attorney, caregiver dynamics, and concerns if proning is even an option if the patient does not improve after a few days given their health condition.  

This brief example is just one of many proning consideration cases that occur in ICUs daily, as patient care among elderly, including proning care, can be very delicate and sometimes more risky than beneficial. Like all other patients, patients must be assessed prior to proning to determine the need, extent, duration, frequency, safety, feasibility, and consent (1-15,30-40). 

The Role of Telemonitoring in Inpatient Care for Patients with ARDS

With the rise of at home patient care, telehealth, and remote patient monitoring, several patients receive post-ARDS and proning management with the click of a button. While telemonitoring has expanded significantly in the past decade as a result of the rise of telehealth nursing, technological advances, and more widespread insurance and Internet coverage, ARDS and proning are still managed in critical care settings. But, even within ICUs and critical care settings nationwide, more and more health care facilities are relying and adopting artificial intelligence (AI) technology, telemonitoring, and surveillance to detect possible early changes in patient vital signs. While nothing can replace physical examination and monitoring by a health care professional, as technology progresses, more technology can be used to detect early possible complications of ARDS, prone positioning, or both (1-20).

Nursing Considerations

Nurses remain the most trusted profession for a reason, and nurses are often pillars of patient care in several health care settings. Patients turn to nurses for guidance, education, and support. While there is no specific guideline for the nurses’ role in ARDS management and proning education, here are some suggestions to provide quality care for patients with ARDS in the prone position (1-15,30-39).

The Nurse’s Role in ARDS Care

Obtain a Health History

Obtain a detailed health history of the patient. Often times, vital signs and history taking can be complex, especially in acute settings. Many times, ARDS patients can have complex medical histories, various inpatient consults before being diagnosed with ARDS or being proned, making critical health history notes lost. As nurses, it is important to be involved in the vital signs, history, and assessment to learn about noticing any abnormalities or medical concerns that warrant medical attention. Also, it is important to assess the patient for any skin changes or mobility concerns that can increase further complications with proning. If a patient appears to have issues with their skin, tubes, or vital signs, take the time to assess and reach out to the care team.

Check for Allergies

Clearly read the medical record to see if the patient has any allergies, especially to certain adhesives or medications. Many eye tapes and padding materials can be made of several ingredients, and many ARDS patients are unable to verbalize allergies by the time they are in the prone position or eligible for prone positioning. Pain medications also can be derived from various sources, making them possible to trigger an allergic reaction. Monitor their skin integrity and breathing for any changes as well since patients cannot verbalize possible allergic reaction symptoms.

Provide Education

Educate the caregivers on pain medication administration and non-pharmacological interventions. Take time to answer any questions about the therapies and to confirm the orders as well.

Document Appropriately

Regardless of how long a client has been in the prone position, ensure documentation is up to date and assessments are still regularly performed.

Review Medications

Review medication history at every encounter. Often times, in busy clinical settings, reviewing health records can be overwhelming, especially for patients with a complex medical history and for patients with ARDS and in the prone position. Confirm medications in the IV bags, the tubes are patent, orders are received and documented, and more to avoid medication errors and compromised patient care.

Involve Interdisciplinary Team

Communicate the care plan to other staff involved for continuity of care. For several patients, especially for patients with ARDS and in the prone position, care often involves a team of nurses, specialists, pharmacies, caregivers, and more. Ensure that patients’ records are up to date for ease in record sharing and continuity of care.

Engage in Self-Education

Stay up to date on continuing education related to ARDS and the prone position, as evidence-based information is always evolving and changing. You can then present your new learnings and findings to other health care professionals and educate your patients with the latest information.

Additional Nursing Roles in ARDS Care 

Unfortunately, it is not possible to look at someone with the naked eye and determine if they are a good candidate for proning given the state of their ARDS. Some patients are more visibly deteriorated and can be a good candidate for proning. Other patients need more assessment and evaluation before considering the prone position.  Since management and presentation can vary widely, adequate assessment and nursing judgment are essential in ARDS care. In addition, nurses can answer questions and concerns regarding ARDS and the prone position for caregivers. Nurses can provide quality care by reviewing the health history, observing patient’s during assessments, addressing caregiver’s concerns, and performing diligent care during repositioning a client (1-10, 20-39). 

• Confirm with the medical records or caregivers of any existing medical conditions or concerns (need to identify risk factors) 
• Confirm with the medical records or caregivers of any existing lifestyle concerns, such as alcohol use, other drug use, sleep habits, diet, surgical history, and allergies (need to identify lifestyle factors that can influence likelihood of ARDS and prone position complications) 
• Observe for any changes to the patient’s body, such as changes in breathing, changes in urination, changes in stool, changes in skin texture (potential prone position complication symptoms) 

Research Findings 

There is extensive publicly available literature on ARDS and prone positioning via the National Institutes of Health (NIH) and other evidence-based journals. For clients interested in participating in clinical trial research, they can seek more information on clinical trials from local universities and health care organizations. 

Conclusion 

Prone positioning is here to stay since someone, somewhere will be at risk for experiencing an ALI and having the likelihood of developing ARDS. Because of the nuanced nature of prone positioning, evidence-based research, facility resources, medical guidelines, patient health history, and clinical judgment will determine the role of prone positioning for several ARDS patients nationwide. 

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