ABG Analysis: A Step-by-Step Guide
This approach focuses on five key components of blood to analyze ABGs.
Arterial blood gas (ABG) analysis is complex and challenging, but a step-by-step approach focusing on five key components of blood can help nurses interpret sample results.
“Strategies for Interpreting Arterial Blood Gases,” in Nursing2024, details steps for understanding ABGs and emphasizes the importance of practice to build interpretation skills and provide appropriate care.
Each blood component relates to a parameter for assessing a patient’s oxygenation status, compensation level, and whether there is an acid-base disturbance that’s respiratory or metabolic. The five components are oxygen saturation (SaO2), dissolved oxygen (PaO2), blood acidity or alkalinity (pH), dissolved carbon dioxide (PaCO2) and bicarbonate concentration (HCO3-).
The article describes a seven-step approach using the example of a patient with ABG results as follows: pH 7.52, PaCO2 30 mm Hg, HCO3- 24 mEq/L, PaO2 89 mm Hg and SaO2 96%.
- Examine PaO2 and SaO2 levels to determine if hypoxemia exists and intervene if necessary.
- Review the pH value and label it as acidic (below 7.4), alkaline (above 7.4) or partially one of those based on the ranges. The 7.52 pH indicates a clear alkalosis.
- Examine PaCO2 to determine if it indicates acidosis (above 45 mm Hg) or alkalosis (below 35 mm Hg). The PaCO2 in this example points toward respiratory alkalosis.
- Review HCO3- for acidosis (below 22 mEq/L) or alkalosis (above 26 mEq/L). In this case, the value is within normal limits.
- Identify the origin of acid-base imbalance (respiratory or metabolic). The low PaCO2 matches the high pH, indicating respiratory alkalosis.
- Determine compensation by checking whether pH is within normal limits and if the values for respiratory and metabolic components are outside normal ranges but in opposite directions.
- Combine the analysis from the previous steps. In this case, the patient has an uncompensated respiratory alkalosis with normal oxygenation.
The article includes five other practice cases, noting that “the best way to gain skill and accuracy in interpreting ABGs is to practice working through many examples, looking at all the components.”
Patient Safety Concerns 2024
Transitioning new clinicians to practice tops ECRI’s patient safety concerns.
Transitioning new clinicians to practice tops the list of patient safety concerns, with lost learning opportunities due to COVID-19 leaving many new nurses less prepared to practice alone.
“Top 10 Patient Safety Concerns 2024,” from ECRI, notes that 96% of new nurses found employment, a much higher rate than clinicians in general, but many less experienced nurses report being insufficiently prepared based on a range of disruptions. “Without sufficient preparation, support, and training, new clinicians can experience loss of confidence, burnout, and reduced mindfulness around culture of safety. The combination of these factors may lead to preventable harm,” adds the annual report.
Safety concerns about transitions to practice are due to a shortage of educational programs and educators, a loss of experienced practitioners because of retirement, and burnout from work overload, the report adds. “At a time when new clinicians are relatively inexperienced, they are asked to do more and work longer, without enough senior clinicians in their network for support, guidance, and mentorship.”
Other safety concerns include:
- Barcode medication administration systems
- Unintended consequences of adopting technology
- Healthcare workers’ declining physical and emotional well-being
“Organizations must calculate each item’s risk score and conduct a gap analysis to evaluate their current practices against our recommendations,” the report notes.
AACN resources to improve transitions for new nurses include the New Nurse Orientation Pathway, an extensive competency program that offers bundling with the AACN Knowledge Assessment Tool and Essentials of Critical Care Orientation, as well as supplemental tools for specific practice areas. AACN also provides several staffing resources, such as advocacy efforts, best practice recommendations and many articles.
In addition, “AACN Standards for Appropriate Staffing in Adult Critical Care,” the specialty’s first, action-oriented staffing standards, are now available. Each of the seven standards includes actions for organizational leaders, clinical leaders and direct care nurses, as well as suggested exemplars, tools and resources.
Mobile Lifts Benefit Ventilated ICU Patients
The use of mobile lifts helped patients on ventilators stand earlier.
Ventilated ICU patients who received rehabilitation with a mobile lift were able to stand earlier and achieve higher Functional Status Scores (FSS) than those using standard protocols.
“Early Mobilization Using a Mobile Patient Lift in the ICU: A Randomized Controlled Trial,” in Critical Care Medicine, notes the first trial of its type met the primary and secondary goals of potential new strategies for using machinery to counteract muscle weakening.
“Using mobile patient lifts for ICU patients on mechanical ventilation may improve their physical function during ICU admission by accelerating the standing process,” the trial notes.
Conducted at a single center in Japan, the trial included 41 patients in the control group and 39 in the intervention group, with the latter receiving assistance to sit, stand, transfer and walk with the mobile patient lift. The intervention group averaged one day for standing on their own to meet the criteria for rehabilitation, compared with three days for the control group.
Patients in the intervention group had higher FSS in the ICU at discharge, averaging 20.4 compared with 17.9 for the control group, and higher ICU mobility scores, averaging 6.0 compared with 4.0 in the control group. “This study suggests that lifting may effectively result in home discharge, as the mean FSS-ICU score was greater than 19 in the intervention group.”
“Early Mobilization in the ICU,” a related article in Chest Critical Care, reviews studies on the effect of mobilization on minimizing ICU-acquired weakness. The review shows that patients have a shorter length of stay, return to independent functional status earlier, and have a shorter duration of delirium. Although some other recent studies have produced mixed results, this review of different timing, duration and method protocols shows that “using an EM [early mobilization] protocol in the context of a quality improvement initiative can enhance patient outcomes.”
In addition, AACN’s website offers many resources on mobility, including CSI projects, journal articles and NTI recorded sessions.
Comparing SBT Methods: Pressure Support Better Than T-Piece
It is the largest review to date that compares weaning methods.
A review comparing protocols for weaning patients off mechanical ventilation finds that pressure support (PS) leads to more successful extubation than T-piece spontaneous breathing trials (SBTs), without increasing the risk of reintubation.
“Spontaneous Breathing Trial Techniques for Extubating Adults and Children Who Are Critically Ill: A Systematic Review and Meta-Analysis,” in JAMA Network Open, compares results from more than 40 trials involving 6,716 critically ill adults and children. The review includes nine new trials, nearly doubling the number of patients from a similar 2017 study.
Low-quality evidence (14 trials, 4,459 patients) reveals that neither method is particularly better than the other. However, when one outlying trial was excluded, findings show that PS patients are 9% more likely to pass an SBT compared with T-piece patients. In addition, PS patients have a 7% greater chance of being successfully extubated without increased risk of reintubation.
While it’s unlikely that any single SBT technique will be optimal for all intubated patients, the review suggests that the PS method facilitated extubation decision-making for unselected critically ill adults or children.
“As such, even if PS SBTs underestimate postextubation work of breathing, successful completion of a PS SBT may offset clinician reluctance to extubate, enabling more timely and successful extubation,” the review notes.
To date, it is the largest review to compare weaning methods, and the findings are strengthened by an extensive search of relevant trials and reliable analysis of different patient groups.
Several limitations are included: The quality of trials reviewed wasn’t always consistent, differences existed in how patients were chosen for SBT, and some studies lacked daily screening that may have delayed SBT attempts.
“Future investigations should include these findings and compare SBT techniques that maximize differences in inspiratory support.”
Updated Guidelines for Brain Death Evaluation
Critical care nurses should understand the guidelines, since BD/DNC evaluations are held in ICUs.
Revised guidelines for brain death/death by neurologic criteria (BD/DNC) aim to ensure a clear and reliable approach to evaluate patients of all ages, thereby strengthening public trust in the medical community’s ability to determine death.
Highlights relevant to critical care are covered in a feature article in Critical Care Medicine, which notes the guidelines should be used to update hospital protocols and determine clinical practice. The 2023 guidelines were compiled jointly by the American Academy of Neurology, American Academy of Pediatrics, Child Neurology Society and Society of Critical Care Medicine.
“Because BD/DNC evaluations are conducted in the ICU, it is essential for members of the critical care community to familiarize themselves with these guidelines,” the article notes, adding that the fundamental concept of BD/DNC has not changed.
“BD/DNC is permanent loss of function of the brain as a whole, including the brain stem, resulting in coma, brainstem areflexia, and apnea in the setting of an adequate stimulus.”
The guidelines provide for a thorough neurological examination, and they list detailed responses consistent with brain death. The protocol explains how to perform apnea testing safely, including modifications for patients on extracorporeal membrane oxygenation.
Other elements in the guidelines include:
- Maintaining a sufficient observation period to ensure there’s no chance of recovery
- Ruling out potentially confounding conditions such as hypothermia, hypotension, severe metabolic disturbances or medication effects
- Providing specific recommendations for patients who received therapeutic hypothermia or medical-surgical interventions to manage intracranial hypertension
- Addressing controversial matters such as consent, BD/DNC evaluation in pregnancy, preservation of neuroendocrine function, and primary posterior fossa injuries
“By adhering to these guidelines, critical care clinicians can confidently navigate the challenging aspects of BD/DNC determination,” the article adds.
Women Still Underrepresented in Heart Failure Trials
The number of women in HF clinical trials needs to be increased.
Although heart disease is the leading cause of death for women, their underrepresentation in clinical trials leaves an ongoing gap in understanding many of the disparities, risk factors and preferred therapies.
“Focus on Heart Failure | Heart Failure in Women: Understanding the Differences to Change the Paradigm,” in Cardiology, notes that interventions are needed to combat declining awareness of the risk of heart disease and heart failure (HF), including increases in incidence among women, especially racial and ethnic minorities.
“Thus, an intentional multifaceted approach that includes a sex-specific focus on primary prevention, deconstructing implicit bias and other barriers to care, ensuring adequate access to and implementation of tailored risk stratification and management regimens, and finally, the enrollment of women in adequate numbers in HF clinical trials, is necessary to balance the scales in sex disparities in HF,” the article adds.
Sex differences that impact risk include physiology, immune responses, hormones and higher likelihood of nonischemic causes among women. The risk factors of obesity and diabetes are more prevalent in women, and social determinants of health and pregnancy can lead to worse outcomes.
Women also may demonstrate different responses to medications and potential adverse effects. The risk for women is underrepresented because of the prevalence of men in clinical trials testing the impact of the medications. Women are less likely to receive referrals for advanced therapies or to receive devices such as implantable cardioverter defibrillators or left ventricular assist devices, the article adds.
The imbalance in available research results in less understanding and knowledge. For example, heart transplants, which are three times as likely to go to men, often fail in women. “Women who do receive a heart transplant against these odds have similar survival to male heart transplant recipients but with increased morbidity particularly regarding graft rejection, again signifying the need for sex-specific studies in post-transplant management.”
NTI at 50: Meet a Learner, Educator, Leader
For 25 years, nursing executive Doug Houghton has ranked among NTI’s most popular session facilitators, presenting on antibiotics and infection, ethics, APRN leadership and more. In this interview, Houghton discusses his NTI experience and his path as a lifelong learner and educator.