Guidelines for the use of an insulin infusion for the management of hyperglycemia in critically ill patients

Objective: To evaluate the literature and identify important aspects of insulin therapy that facilitate safe and effective infusion therapy for a defined glycemic end point. Methods: Where available, the literature was evaluated using Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) methodology to assess the impact of insulin infusions on outcome for general intensive care unit patients and those in specific subsets of neurologic injury, traumatic injury, and cardiovascular surgery. Elements that contribute to safe and effective insulin infusion therapy were determined through literature review and expert opinion. The majority of the literature supporting the use of insulin infusion therapy for critically ill patients lacks adequate strength to support more than weak recommendations, termed suggestions, such that the difference between desirable and undesirable effect of a given intervention is not always clear. Recommendations: The article is focused on a suggested glycemic control end point such that a blood glucose ≥150 mg/dL triggers interventions to maintain blood glucose below that level and absolutely <180 mg/dL. There is a slight reduction in mortality with this treatment end point for general intensive care unit patients and reductions in morbidity for perioperative patients, postoperative cardiac surgery patients, post-traumatic injury patients, and neurologic injury patients. We suggest that the insulin regimen and monitoring system be designed to avoid and detect hypoglycemia (blood glucose ≤70 mg/dL) and to minimize glycemic variability. Important processes of care for insulin therapy include use of a reliable insulin infusion protocol, frequent blood glucose monitoring, and avoidance of finger-stick glucose testing through the use of arterial or venous glucose samples. The essential components of an insulin infusion system include use of a validated insulin titration program, availability of appropriate staffing resources, accurate monitoring technology, and standardized approaches to infusion preparation, provision of consistent carbohydrate calories and nutritional support, and dextrose replacement for hypoglycemia prevention and treatment. Quality improvement of glycemic management programs should include analysis of hypoglycemia rates, run charts of glucose values <150 and 180 mg/dL. The literature is inadequate to support recommendations regarding glycemic control in pediatric patients. Conclusions: While the benefits of tight glycemic control have not been definitive, there are patients who will receive insulin infusion therapy, and the suggestions in this article provide the structure for safe and effective use of this therapy.

End-tidal carbon dioxide measurements as a prognostic indicator of outcome in cardiac arrest.

PURPOSE: To evaluate the use of end-tidal carbon dioxide values in predicting survival in cardiopulmonary arrest. BACKGROUND: The decision about when to terminate resuscitative efforts for patients with cardiopulmonary arrest is often subjective. End-tidal carbon dioxide values have been suggested as potential objective criteriafor making this decision. METHODS: This study was a cooperative effort of the St Louis chapter of the American Association of Critical-Care Nurses and its members and involved 6 hospitals and an air evacuation service. All adult patients who had a cardiopulmonary arrest were eligiblefor the study. Once a patient with cardiac arrest was intubated, end-tidal carbon dioxide and cardiac rhythms were measured and recorded every 5 minutes for 20 minutes or until resuscitation efforts were terminated. Patients' survival at the time of the arrest, survival 24 hours after the arrest, and discharge status were followed up. RESULTS: A total of 127 patients were enrolled in the study. All but 1 patient with end-tidal carbon dioxide values less than 10 mm Hg died before discharge. End-tidal carbon dioxide values greater than 10 mm Hg were associated with various degrees of survival. Overall survival to discharge was less than 14%, regardless of the end-tidal carbon dioxide value. CONCLUSION: Measurements of end-tidal carbon dioxide can be used to accurately predict nonsurvival of patients with cardiopulmonary arrest. End-tidal carbon dioxide levels should be monitored during cardiopulmonary arrest and should be considered a useful prognostic value for determining the outcome of resuscitative efforts.

Comparison of pulmonary artery and central venous pressure waveform measurements via digital and graphic measurement methods.

BACKGROUND: Techniques to measure pulmonary artery (PA) pressure waveforms include digital measurement, graphic measurement, and freeze-cursor measurement. Previous studies reported the inaccuracy of digital and freeze-cursor measurements. However, many of the previous studies were small and did not thoroughly examine the circumstances of when digital measurements might be inaccurate. OBJECTIVES: To compare digital measurements and graphic measurements of PA and central venous pressure (CVP) waveforms in patients with a variety of respiratory patterns, and to compare digital measurements and graphic measurements of CVPs in patients with abnormal or right ventricular waveforms. METHODS: A total of 928 patients were enrolled in this study. Waveforms from the PA and CVP were collected from each patient. The monitor pressure value (digital measurement) printed on the recorded waveform was compared with the pressure value obtained by a graphic strip recording and measured by one of the primary investigators (graphic measurement). RESULTS: Digital measurements were found to be inaccurate in measuring waveforms in all respiratory categories and in measuring right ventricular waveforms. PA diastolic values and CVP values were the most inaccurately measured waveforms. Digital errors of more than 4 mm Hg were common. CONCLUSION: There were instances in which the monitor's digital measurement was substantially different from the graphically measured value. This difference has the potential to mislead interpretation of clinical situations. The monitor's ability to occasionally give digital measurement values similar to the graphic measurements may lead to a false sense of security in clinicians. Because the accuracy of the monitor is inconsistent, the bedside clinician should interpret waveforms through use of a graphic recording rather than rely on the digital measurement on the monitor.

Hemodynamic applications of capnography.

The measurement of the pressure of exhaled carbon dioxide (PetCO2) via capnography has several useful hemodynamic applications. This article discusses integrating PetCO2 values with hemodynamic assessment. Capnography can be applied to hemodynamic assessment in three key ways: (1) identification of end-expiration during pulmonary artery and central venous pressure measurements, (2) assessment of pulmonary perfusion and alveolar deadspace, (3) assessment of cardiopulmonary resuscitative efforts. The article presents research, sample waveforms for end-expiration identification, and case examples.

Point of care testing in critical care.

POCT is rapidly expanding in today's critical care areas. Nurses need to be involved in the implementation and evaluation process of POCT at every step. Each institution must determine which bedside tests are indicated based on an in-depth analysis of test accuracy, positive clinical impact, and cost-benefit ratio. Generally speaking, the progress in technology over the last two decades has resulted in highly accurate tests used for POCT. However, accuracy of the test is contingent on correct calibration and correct usage by the test performer. Reduced TAT, particularly therapeutic time, is the major advantage to POCT. The clinician identifies the need for a blood analysis and within seconds to minutes has a measurement upon which to change or implement an intervention. For the critically ill patient this can potentially save lives and allow for rapid titration of medications or mechanical ventilation, as well as decrease intubation times and ICU length of stay. Reduction in blood loss for the patient is the second major advantage of POCT. POCT requires 2 drops of blood for analysis versus 3 mL or greater for a test sent to the laboratory for analysis. The cost-benefit examination needs to occur from many views. The cost of education, supplies, and personnel of POCT versus laboratory testing are a few key aspects. However, because different testing techniques exist, it is difficult to do absolute cost comparisons. In addition, cost savings of faster ventilator weaning or decreased ICU length of stay are also important factors to include. Lastly, costs are not just financial costs. In addition, clinicians should examine the cost to patients regarding comfort and quicker discharge. These are quality indicators from the patient's perspective. POCT offers many advantages, but surrounding the implementation of this technology is a multitude of questions that each institution must answer prior to undertaking a POCT program.

Clinical application. Using oxygenation profiles to manage patients.

Cellular oxygenation is dependent on both tissue oxygenation and pulmonary oxygenation. The use of profiles can help to make the assessment of tissue and pulmonary oxygenation more thorough. Although oxygenation profiles have limitations, an understanding of them can provide useful information to the critical care nurse. Oxygenation profiles enable the nurse to trend a patient's progress and response to nursing and medical interventions. A sophisticated assessment relies not merely on physical assessment alone but incorporates continuous mixed venous oxygenation and oxygenation profiles to assess a patient's tissue and pulmonary oxygenation status.