Entropy and bispectral index for assessment of sedation, analgesia and the effects of unpleasant stimuli in critically ill patients: an observational study

INTRODUCTION: Sedative and analgesic drugs are frequently used in critically ill patients. Their overuse may prolong mechanical ventilation and length of stay in the intensive care unit. Guidelines recommend use of sedation protocols that include sedation scores and trials of sedation cessation to minimize drug use. We evaluated processed electroencephalography (response and state entropy and bispectral index) as an adjunct to monitoring effects of commonly used sedative and analgesic drugs and intratracheal suctioning. METHODS: Electrodes for monitoring bispectral index and entropy were placed on the foreheads of 44 critically ill patients requiring mechanical ventilation and who previously had no brain dysfunction. Sedation was targeted individually using the Ramsay Sedation Scale, recorded every 2 hours or more frequently. Use of and indications for sedative and analgesic drugs and intratracheal suctioning were recorded manually and using a camera. At the end of the study, processed electroencephalographical and haemodynamic variables collected before and after each drug application and tracheal suctioning were analyzed. Ramsay score was used for comparison with processed electroencephalography when assessed within 15 minutes of an intervention. RESULTS: The indications for boli of sedative drugs exhibited statistically significant, albeit clinically irrelevant, differences in terms of their association with processed electroencephalographical parameters. Electroencephalographical variables decreased significantly after bolus, but a specific pattern in electroencephalographical variables before drug administration was not identified. The same was true for opiate administration. At both 30 minutes and 2 minutes before intratracheal suctioning, there was no difference in electroencephalographical or clinical signs in patients who had or had not received drugs 10 minutes before suctioning. Among patients who received drugs, electroencephalographical parameters returned to baseline more rapidly. In those cases in which Ramsay score was assessed before the event, processed electroencephalography exhibited high variation. CONCLUSIONS: Unpleasant or painful stimuli and sedative and analgesic drugs are associated with significant changes in processed electroencephalographical parameters. However, clinical indications for drug administration were not reflected by these electroencephalographical parameters, and barely by sedation level before drug administration or tracheal suction. This precludes incorporation of entropy and bispectral index as target variables for sedation and analgesia protocols in critically ill patients.

Titration and implementation of neurally adjusted ventilatory assist in critically ill patients

BACKGROUND: Neurally adjusted ventilatory assist (NAVA) delivers assist in proportion to the patient's respiratory drive as reflected by the diaphragm electrical activity (EAdi). We examined to what extent NAVA can unload inspiratory muscles, and whether unloading is sustainable when implementing a NAVA level identified as adequate (NAVAal) during a titration procedure. METHODS: Fifteen adult, critically ill patients with a Pao(2)/fraction of inspired oxygen (Fio(2)) ratio < 300 mm Hg were studied. NAVAal was identified based on the change from a steep increase to a less steep increase in airway pressure (Paw) and tidal volume (Vt) in response to systematically increasing the NAVA level from low (NAVAlow) to high (NAVAhigh). NAVAal was implemented for 3 h. RESULTS: At NAVAal, the median esophageal pressure time product (PTPes) and EAdi values were reduced by 47% of NAVAlow (quartiles, 16 to 69% of NAVAlow) and 18% of NAVAlow (quartiles, 15 to 26% of NAVAlow), respectively. At NAVAhigh, PTPes and EAdi values were reduced by 74% of NAVAlow (quartiles, 56 to 86% of NAVAlow) and 36% of NAVAlow (quartiles, 21 to 51% of NAVAlow; p < or = 0.005 for all). Parameters during 3 h on NAVAal were not different from parameters during titration at NAVAal, and were as follows: Vt, 5.9 mL/kg predicted body weight (PBW) [quartiles, 5.4 to 7.2 mL/kg PBW]; respiratory rate (RR), 29 breaths/min (quartiles, 22 to 33 breaths/min); mean inspiratory Paw, 16 cm H(2)O (quartiles, 13 to 20 cm H(2)O); PTPes, 45% of NAVAlow (quartiles, 28 to 57% of NAVAlow); and EAdi, 76% of NAVAlow (quartiles, 63 to 89% of NAVAlow). Pao(2)/Fio(2) ratio, Paco(2), and cardiac performance during NAVAal were unchanged, while Paw and Vt were lower, and RR was higher when compared to conventional ventilation before implementing NAVAal. CONCLUSIONS: Systematically increasing the NAVA level reduces respiratory drive, unloads respiratory muscles, and offers a method to determine an assist level that results in sustained unloading, low Vt, and stable cardiopulmonary function when implemented for 3 h.

Resource use and outcome in critically ill patients with hematological malignancy: a retrospective cohort study

INTRODUCTION: The paucity of data on resource use in critically ill patients with hematological malignancy and on these patients' perceived poor outcome can lead to uncertainty over the extent to which intensive care treatment is appropriate. The aim of the present study was to assess the amount of intensive care resources needed for, and the effect of treatment of, hemato-oncological patients in the intensive care unit (ICU) in comparison with a nononcological patient population with a similar degree of organ dysfunction. METHODS: A retrospective cohort study of 101 ICU admissions of 84 consecutive hemato-oncological patients and 3,808 ICU admissions of 3,478 nononcological patients over a period of 4 years was performed. RESULTS: As assessed by Therapeutic Intervention Scoring System points, resource use was higher in hemato-oncological patients than in nononcological patients (median (interquartile range), 214 (102 to 642) versus 95 (54 to 224), P < 0.0001). Severity of disease at ICU admission was a less important predictor of ICU resource use than necessity for specific treatment modalities. Hemato-oncological patients and nononcological patients with similar admission Simplified Acute Physiology Score scores had the same ICU mortality. In hemato-oncological patients, improvement of organ function within the first 48 hours of the ICU stay was the best predictor of 28-day survival. CONCLUSION: The presence of a hemato-oncological disease per se is associated with higher ICU resource use, but not with increased mortality. If withdrawal of treatment is considered, this decision should not be based on admission parameters but rather on the evolutional changes in organ dysfunctions.

Excellent outcome after surgical treatment of massive pulmonary embolism in critically ill patients

OBJECTIVE: Treatment of central and paracentral pulmonary embolism in patients with hemodynamic compromise remains a subject of debate, and no consensus exists regarding the best method: thrombolytic agents, catheter-based thrombus aspiration or fragmentation, or surgical embolectomy. We reviewed our experience with emergency surgical pulmonary embolectomy. METHODS: Between January of 2000 and March of 2007, 25 patients (17 male, mean age 60 years) underwent emergency open embolectomy for central and paracentral pulmonary embolism. Eighteen patients presented in cardiogenic shock, 8 of whom had cardiac arrest and required cardiopulmonary resuscitation. All patients underwent operation with mild hypothermic cardiopulmonary bypass. Concomitant procedures were performed in 8 patients (3 coronary artery bypass grafts, 2 patent foramen ovale closures, 4 ligations of the left atrial appendage, 3 removals of a right atrial thrombus). Follow-up is 96% complete with a median of 2 years (range, 2 months to 6 years). RESULTS: All patients survived the procedure, but 2 patients died in the hospital on postoperative days 1 (intracerebral bleeding) and 11 (multiorgan failure), accounting for a 30-day mortality of 8% (95% confidence interval: 0.98-0.26). Four patients died later because of their underlying disease. Pre- and postoperative echocardiographic pressure measurements demonstrated the reduction of the pulmonary hypertension to half of the systemic pressure values or less. CONCLUSION: Surgical pulmonary embolectomy is an excellent option for patients with major pulmonary embolism and can be performed with minimal mortality and morbidity. Even patients who present with cardiac arrest and require preoperative cardiopulmonary resuscitation show satisfying results. Immediate surgical desobstruction favorably influences the pulmonary pressure and the recovery of right ventricular function, and remains the treatment of choice for patients with massive central and paracentral embolism with hemodynamic and respiratory compromise.