Effect of flumazenil on diaphragm electrical activation during weaning from mechanical ventilation after acute respiratory distress syndrome.

BACKGROUND: Diaphragm electrical activation (EAdi) and the ratio of tidal volume to EAdi (VT/EAdi) may provide clinical information on neuroventilatory efficiency (NVE) in patients being weaned from mechanical ventilation. We tested the hypothesis that residual sedation could interfere with respiratory recovery, by assessing the effects of flumazenil on EAdi and VT/EAdi ratio. METHODS: This observational study included 13 patients breathing with pressure-support ventilation (PSV) after a long period of controlled mechanical ventilation (i.e. >4 days) plus midazolam-based sedation for acute respiratory distress syndrome. EAdi and respiratory patterns were compared before and after a bolus of flumazenil, which was given because neurological status needed to be evaluated. RESULTS: Flumazenil induced a significant increase in EAdi [+71 (41-123)%, P=0.0002] and VT [+17 (8-32)%, P=0.0005], resulting in significantly decreased NVE [-34 (15-43)%]. The increased VT was significantly correlated with the increased EAdi (ρ=0.70, P=0.009). CONCLUSIONS: During weaning from mechanical ventilation, the diaphragmatic contribution to the breathing process may be reduced by residual midazolam-induced ventilatory depression. The increased EAdi with reversal of residual sedation was associated with a proportional increase in VT. These findings should be considered by the attending physician when interpreting daily EAdi and VT changes during weaning from mechanical ventilation.

Neuro-ventilatory efficiency during weaning from mechanical ventilation using neurally adjusted ventilatory assist.

BACKGROUND: Neuro-ventilatory efficiency (NVE), defined as the tidal volume to electrical diaphragm-activity ratio (VT/EAdi) at the beginning and end of the weaning process after acute hypoxaemic respiratory failure, may provide valuable information about patient recovery. METHODS: This observational study included 12 patients breathing with neurally adjusted ventilatory assist (NAVA). When a spontaneous breathing trial (SBT) with pressure support of 7 cm H2O and PEEP was unsuccessful, NAVA was used and the level was adjusted to obtain an EAdi of ∼60% of maximal EAdi during SBT. VT and EAdi were recorded continuously. We compared changes in NVE between NAVA and SBT at the first failed and first successful SBT. RESULTS: When patients were switched from NAVA to SBT, NVE was significantly reduced during both unsuccessful and successful SBT (-56 and -38%, respectively); however, this reduction was significantly lower when SBT was successful (P=0.01). Between the first and last day of weaning, we observed that NVE decreased with NAVA [40.6 (27.7-89.5) vs 28.8 (18.6-46.7); P=0.002] with a significant decrease in NAVA level, whereas it remained unchanged during SBT [15.4 (10.7-39.1) vs 19.5 (11.6-29.6); P=0.50] with significant increases in both EAdi and VT and no difference in respiratory rhythm. CONCLUSIONS: These results suggest that in patients after respiratory failure and prolonged mechanical ventilation, changes in VT and NVE, between SBTs are indicative of patient recovery. Larger clinical trials are needed to clarify whether changes in NVE reliably predict weaning in patients ventilated with NAVA.

Electronic ventilator temperature sensors as a potential source of respiratory tract colonization with Stenotrophomonas maltophilia.

Stenotrophomonas maltophilia (S. maltophilia) is an important cause of nosocomial infection among ventilated and immunocompromised patients, and among patients receiving broad-spectrum antimicrobials. We report a cluster of patients in a surgical intensive care unit who were colonized or infected with S. maltophilia. An epidemiological investigation was initiated after surveillance data revealed that eight patients were culture-positive from sputum for S. maltophilia in the preceding month. Review of respiratory care procedures revealed that when mechanical ventilators were serviced between patients, the electronic temperature probes used with servo-controlled humidifiers were wiped with inadequate disinfection. We collected cultures of case-patient room surfaces, sinks and ventilator equipment. S. maltophilia was recovered from room surfaces, ventilator expiratory circuits and a temperature sensor which had been kept in ambient air after disinfection. Patients and environmental isolates were examined by RAPD-PCR. Three clinical isolates and one environmental isolate had the same profile, which suggests cross-contamination or common source exposure. The outbreak was controlled by adequate disinfection of the temperature sensors. No single epidemic strain was identified but several observations support the conclusion that the temperature probes contributed to the outbreak.

[Changes in kaliemia following rapid sequence induction with succinylcholine in critically ill patients]. / Variation de kaliémie après une induction en séquence rapide avec la succinylcholine chez les patients de réanimation.

OBJECTIVE: Evaluate the changes in potassium following rapid sequence induction with succinylcholine in critically ill-patients and determine whether hospital length of stay could influence the succinylcholine-induced hyperkaliemia. STUDY DESIGN: Prospective and observational study. PATIENTS AND METHODS: After approval by our local ethical committee, we prospectively included 36 patients admitted from more than 24hours in ICU and who required succinylcholine for rapid tracheal intubation (1mg/kg). Serum potassium was measured before, 5 and 30min after succinylcholine. The incidence of life-threatening hyperkaliemia (≥6.5mmol/L) was noted. RESULTS: We could observe significant and transient increase in serum potassium (median increase of 0.45 [0.20-0.80] mmol/L at five minutes). A significant relationship was observed between the ICU length of stay and arterial potassium increase (r=0.37, P<0.05). From the ROC curve, a threshold of 12 days had an 86% sensitivity and 69% specificity in discriminating patients in whom the potassium increase was more than 1.5mmol/L. CONCLUSION: Induction with succinylcholine is followed by significant but transient hyperkaliema. The ICU length of stay before giving succinylcholine could influence significantly the amplitude of potassium increase.

[Diagnosis and management of acute mesenteric ischemia]. / Diagnostic et prise en charge des ischémies mésentériques aiguës.

The prevalence of significant splanchnic arterial stenoses is increasing, but remains mostly asymptomatic due to abundant collateral circulation. Acute insufficiency of mesenteric arterial blood flow accounts for 60 to 70% of cases of mesenteric ischemia and results mostly from a superior mesenteric embolus. Despite major advances have been achieved in understanding the pathogenic mechanisms of bowel ischemia, its prognosis remains dismal with mortality rates about 60%. The diagnosis of acute mesenteric ischemia depends upon a high clinical suspicion, especially in patients with known risk factors. Rapid diagnosis is essential to prevent intestinal infarction. However, early signs and symptoms of mesenteric ischemia are non specific, and definitive diagnosis often requires radiologic examinations. Early and liberal implementation of angiography has been the major advance over the past 30 years which allowed increasing diagnostic accuracy of acute mesenteric ischemia. CT and MR-based angiographic techniques have emerged as alternatives less invasive and more accurate to analyse splanchnic vessels and evaluate bowel infarction. The goal of treatment of patients with acute mesenteric ischemia is to restore intestinal oxygenation as quickly as possible after initial management that includes rapid hemodynamic monitoring and support. Surgery should not be delayed in patients suspected of having intestinal necrosis.

Pharmacokinetics of free ertapenem in critically ill septic patients: intermittent versus continuous infusion.

BACKGROUND: The aim of this paper was to compare the pharmacokinetic and pharmacodynamic (PK/PD) parameters of continuous (CI) and intermittent infusion (ITI) of ertapenem into critically ill patients with severe abdominal infections. METHODS: Twenty septic patients hospitalized in a university hospital intensive care unit were enrolled in the study. Half of the patients received ertapenem as an ITI 1 g bolus once daily, and the other half of the patients received the same dose via CI over 24 h following a 1-g loading dose. Blood was drawn 1, 12 and 24 h after terminating ITI or on days 2, 3 and 5 after starting CI for each patient. After centrifugation, the drawn blood was frozen at -80 °C until being examined by high-performance liquid-chromatography analysis. RESULTS: Median serum-free ertapenem concentrations were as follows: ƒCmax = 98.9 mg/L and ƒCmin = 2.5 mg/L for ITI, and ƒCss=15.9 mg/L for CI. The ITI and CI median total clearance and volumes of distribution were 2.2 L/h vs. 2.5 L/h and 15.4 L vs. 21.0 L, respectively. The ertapenem MIC ranges were as follows: Escherichia coli (0.006 to 0.5 mg/L), Enterobacter cloacae (0.023 to 0.5 mg/L), Klebsiella oxytoca (0.023 to 0.5 mg/L), Staphylococcus aureus (0.38 to 3 mg/L), Streptococcus viridians (0.38 to 3 mg/L) and Enterococcus faecalis (0.38 to 3 mg/L). ITI and CI provided steady-state serum-free ertapenem concentrations constantly above the MIC for all bacteria. CONCLUSION: Ertapenem exhibited satisfactory PK/PD parameters and achieved serum-free concentrations 100% of the time, above even the high MIC of extracellular pathogens normally encountered during severe abdominal infections. CI administration resulted in equally effective PK/PD parameters as ITI in normal weight, good renal-function patients.

[Stomach rupture associated with noninvasive ventilation]. / Rupture gastrique au décours d'une séance de ventilation non invasive.

Noninvasive positive-pressure ventilation (NIPPV) is a safe method to treat acute respiratory failure and is known to decrease the need for intubation and the length of ICU-stay. Few severe complications have been reported even when the indications are respected. Some rare cases of gastric distension were recently described. We report the case of a gastric perforation associated with NIPPV. The treatment was closure with a primary interrupted two-layer suture. Recovery was complete and the patient was transferred to the ward on Day 11.