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.

National survey of central venous catheter flushing in the intensive care unit.

BACKGROUND: Evidence is needed on the best solution for flushing central venous catheters. OBJECTIVE: To understand current flushing practices for short-term central venous catheters among critical care nurses before implementation of a randomized, controlled trial comparing physiological saline with heparin solution for flushing to maintain catheter patency. METHODS: A 6-item survey including demographic data was mailed to 2000 practicing critical care nurses in the United States. An additional 316 surveys were completed at the annual conference of the American Association of Critical-Care Nurses. RESULTS: Most (71.5%) of the 632 respondents who completed the survey were staff nurses. Most respondents (64.6%; 95% CI, 60.86%-68.34%) reported using physiological saline exclusively to flush central venous catheters and maintain patency. For heparin-containing solutions, the concentration and volume used varied. The most commonly reported volumes for flushing were 10 mL for saline (63%; 95% CI, 59.18%-66.82%) and 3 mL for heparin (50.2%; 95% CI, 43.5%-56.9%). CONCLUSION: Flushing practices for central venous catheters vary widely. A randomized controlled trial is needed to determine the optimal flushing solution to maintain short-term patency.

Systems biology in critical-care nursing.

Systems biology applies advances in technology and new fields of study including genomics, transcriptomics, proteomics, and metabolomics to the development of new treatments and approaches of care for the critically ill and injured patient. An understanding of systems biology enhances a nurse's ability to implement evidence-based practice and to educate patients and families on novel testing and therapies. Systems biology is an integrated and holistic view of humans in relationship with the environment. Biomarkers are used to measure the presence and severity of disease and are rapidly expanding in systems biology endeavors. A systems biology approach using predictive, preventive, and participatory involvement is being utilized in a plethora of conditions of critical illness and injury including sepsis, cancer, pulmonary disease, and traumatic injuries.

Gastric residual volume and aspiration in critically ill patients receiving gastric feedings.

BACKGROUND: The helpfulness of bedside assessment of gastric residual volume in the prediction of aspiration has been questioned, as has the volume that signals increased risk of aspiration. OBJECTIVE: To describe the association between gastric residual volumes and aspiration of gastric contents. METHODS: In a prospective study of 206 critically ill patients receiving gastric tube feedings for 3 consecutive days, gastric residual volumes were measured with 60-mL syringes every 4 hours. Measured volumes were categorized into 3 overlapping groups: at least 150 mL, at least 200 mL, and at least 250 mL. Patients were categorized as frequent aspirators if 40% or more of their tracheal secretions were positive for pepsin and as infrequent aspirators if less than 40% of their secretions were positive for pepsin. Gastric residual volumes were compared between the 2 aspiration groups. RESULTS: Approximately 39% of the 206 patients had 1 or more gastric residual volumes of at least 150 mL, 27% had 1 or more volumes of at least 200 mL, and 17% had 1 or more volumes of at least 250 mL. Large-bore tubes identified most of the high volumes. Eighty-nine patients were frequent aspirators. Volumes less than 150 mL were common in both aspiration groups. However, the frequent aspirators had a significantly greater frequency of 2 or more volumes of at least 200 mL and 1 or more volumes of at least 250 mL. CONCLUSIONS: No consistent relationship was found between aspiration and gastric residual volumes. Although aspiration occurs without high gastric residual volumes, it occurs significantly more often when volumes are high.

Improved extubation rates and earlier liberation from mechanical ventilation with implementation of a daily spontaneous-breathing trial protocol.

BACKGROUND: Daily spontaneous-breathing trials (SBTs) are promulgated as the best method for assessing readiness for discontinuation of mechanical ventilation. SBT protocols have also been shown to improve outcomes as opposed to wild-type implementation of daily SBT recommendations. Here we determine whether implementation of a mandatory, protocol-driven daily SBT on all ventilated patients in the ICU improves extubation rates and accelerates liberation from mechanical ventilation. STUDY DESIGN: A daily 30-minute SBT protocol was introduced into an academic surgical ICU in July 2005 and followed through September 2006. Decisions about next steps (continued mechanical support versus liberation) after each trial were recorded. Owing to the low liberation rate, physicians began (in January 2006) recording the reasons for continuing mechanical ventilation after a passing SBT. Differences in patient outcomes were compared for the first and last 8 weeks of the study period, corresponding to similar times in the academic and calendar years. RESULTS: Four hundred eighty-eight patients experienced 547 mechanical ventilation episodes from July 2005 to September 2006. A total of 2,835 safety evaluations for SBTs were completed. Rate of extubations of passing patients after the first 8 weeks of implementation (n = 73 patients) was 27% (35 extubations of 131 passed trials). This rate improved in the last 8 weeks to 42% (42 of 101) (p < 0.02) (n = 57 patients). Reintubation rate was similar at 6% for the first 8 weeks and 8% for the final 8 weeks (p = 0.65), including self-extubations. CONCLUSIONS: Implementation of a daily SBT protocol resulted in improvement of extubation rates during the year of implementation without a change in the reintubation rate. Requesting that physicians enumerate reasons for continuing mechanical ventilation in the face of a passing breathing trial was associated with a sustained improvement in extubation rate.

Comparison of forehead and digit oximetry in surgical/trauma patients at risk for decreased peripheral perfusion.

OBJECTIVE: Measurement of pulse oximetry (Spo(2)) is often impaired in critically ill patients. Forehead reflectance oximetry, the Max-Fast (Nellcor, Pleasanton, CA), may be less susceptible to poor tissue perfusion and could improve accuracy of oxygen saturation measurement. The objective of this study was to evaluate the use of forehead oximetry measures in critically ill surgical/trauma patients. METHODS: A prospective interventional study of 30 critically ill surgical/trauma patients at risk for decreased peripheral perfusion, as evidenced by need for vasopressor support (24 patients), transfusion of more than 6 unit packed cells in 24 hours (two patients), or an inability to obtain consistent saturation from a digit sensor (four patients), compared forehead and digit-based oximeter Spo(2) readings with co-oximetry (Sao(2)) measurements from arterial blood samples. Sao(2) values were converted to functional oxygen saturation (SO(2)) measurements for the final comparison. Patients were fitted with forehead (Nellcor Max-Fast) and digit (Nellcor Max A; digit 1) sensors connected to Nellcor OxiMax N-595 oximeters and a digit sensor (Nellcor Max A; digit 2) connected to a multiparameter monitor (Philips CMS [Andover, MA]). Three measurements of Sao(2) were obtained from each subject over a 24-hour time period, and simultaneous measurements of Spo(2) were recorded from the three monitors. RESULTS: The three Spo(2) measurements (forehead, digit 1, and digit 2) were compared with SO(2) values using the Bland-Altman method to assess agreement. Forehead measurements demonstrated a mean bias of -1.39, whereas digit 1 was -2.61 and digit 2 was -3.84. Pearson correlations (r) for forehead, digit 1, and digit 2 with SO(2) were .834, .433, and .254, respectively. There were fewer unsuccessful measurements with the forehead oximetry technique. CONCLUSIONS: Forehead sensors improve measurement of oxygen saturation in critically ill surgical/trauma patients at risk for decreased peripheral perfusion.

Physicians' estimates of cardiac index and intravascular volume based on clinical assessment versus transesophageal Doppler measurements obtained by critical care nurses.

OBJECTIVES: To compare physicians' estimates of cardiac index and intravascular volume with transesophageal Doppler measurements obtained by critical care nurses, to assess the overall safety of transesophageal Doppler imaging by critical care nurses, and to compare hemodynamic measurements obtained via transesophageal Doppler imaging with those obtained via pulmonary artery catheterization. METHODS: Data were collected prospectively on 106 patients receiving mechanical ventilation. Physicians estimated cardiac index and intravascular volume status by using bedside clinical assessment; critical care nurses, by using transesophageal Doppler imaging. In 24 patients, Doppler measurements were obtained within 6 hours of placement of a pulmonary artery catheter and recording of cardiac output and pulmonary artery occlusion pressure. RESULTS: With Doppler measurements as the reference, physicians correctly estimated cardiac index in 46 (43.8%) of 105 patients, underestimated it in 24 (22.9%), and overestimated it in 35 (33.3%). They correctly estimated volume status in 31 patients (29.5%), underestimated it in 16 (15.2%), and overestimated it in 58 (55.2%). Doppler measurements of cardiac output correlated with those obtained via pulmonary artery catheterization (r = 0.778; P < .001). Two patients had minor complications: dislodgement of a nasogastric tube and inability to obtain a Doppler signal. CONCLUSION: Physicians' assessment of cardiac index and intravascular volume in patients receiving mechanical ventilation is correct less than half of the time. Transesophageal Doppler imaging by critical care nurses appears to be a safe method for measuring cardiac index and estimating intravascular volume. Measurements obtained via Doppler imaging correlate well with those obtained via pulmonary artery catheterization.

Will my patient survive this cardiac arrest?

The authors describe how capnography is used to predict patient outcomes during cardiopulmonary resuscitation.