Olivier Fourcade

The importance of increased neck circumference to intubation difficulties in obese patients.

BACKGROUND: Using the intubation difficulty scale (IDS), we sought to confirm that obese patients are more difficult to intubate than lean patients. We assessed classical bedside tests and included neck circumference. METHODS: We prospectively compared the incidence of difficult tracheal intubation in 70 obese [body mass index (BMI) ≥30 kg/m2] and 61 lean patients (BMI <30 kg/m2). The IDS scores, categorized as difficult intubation (IDS >5) or not (IDS ≤5), and the patient data, were compared between lean and obese patients. Preoperative measurements [BMI, neck circumference (at the level of the thyroid cartilage), width of mouth opening, sternomental distance, and thyromental distance], medical history of obstructive sleep apnea syndrome, and several scores (Mallampati, Wilson, El Ganzouri) were recorded. The view during direct laryngoscopy was graded, and the IDS was recorded. We then compared patients with IDS ≤5 and >5, concerning each item. RESULTS: The results indicate that difficult tracheal intubation is more frequent in obese than in lean patients (14.3% vs 3%; P = 0.03). In the patients with IDS > 5, thyromental distance, BMI, large neck circumference, and higher Mallampati score were the only predictors of potential intubation problems. CONCLUSION: We found that problematic intubation was associated with thyromental distance, increasing neck circumference, BMI, and a Mallampati score of ≥3. Neck circumference should be assessed preoperatively to predict difficult intubation.

Lactate clearance for death prediction in severe sepsis or septic shock patients during the first 24 hours in Intensive Care Unit: an observational study

BackgroundThis study was design to investigate the prognostic value for death at day-28 of lactate course and lactate clearance during the first 24 hours in Intensive Care Unit (ICU), after initial resuscitation.MethodsProspective, observational study in one surgical ICU in a university hospital. Ninety-four patients hospitalized in the ICU for severe sepsis or septic shock were included. In this septic cohort, we measured blood lactate concentration at ICU admission (H0) and at H6, H12, and H24. Lactate clearance was calculated as followed: [(lactateinitial - lactatedelayed)/ lactateinitial] x 100%].ResultsThe mean time between severe sepsis diagnosis and H0 (ICU admission) was 8.0 ± 4.5 hours. Forty-two (45%) patients died at day 28. Lactate clearance was higher in survivors than in nonsurvivors patients for H0-H6 period (13 ± 38% and −13 ± 7% respectively, p = 0.021) and for the H0-H24 period (42 ± 33% and −17 ± 76% respectively, p < 0.001). The best predictor of death at day 28 was lactate clearance for the H0-H24 period (AUC = 0.791; 95% CI 0.6-0.85). Logistic regression found that H0-H24 lactate clearance was independently correlated to a survival status with a p = 0.047 [odds ratio = 0.35 (95% CI 0.01-0.76)].ConclusionsDuring the first 24 hr in the ICU, lactate clearance was the best parameter associated with 28-day mortality rate in septic patients. Protocol of lactate clearance-directed therapy should be considered in septic patients, even after the golden hours.

WAKEFULNESS AND LOSS OF AWARENESS: BRAIN AND BRAINSTEM INTERACTION IN THE VEGETATIVE STATE

Objective: The ascending reticular activating system (ARAS) modulates circadian wakefulness, which is preserved in a persistent vegetative state (PVS). Its metabolism is preserved. Impairment of metabolism in the polymodal associative cortices (i.e., precuneus) is characteristic of PVS where awareness is abolished. Because the interaction of these 2 structures allows conscious sensory perception, our hypothesis was that an impaired functional connectivity between them participates in the loss of conscious perception. Methods: 15O-radiolabeled water PET measurement of regional cerebral blood flow (rCBF) was performed at rest and during a proprioceptive stimulation. Ten patients in PVS and 10 controls were compared in a cross-sectional study. The functional connectivity from the primary sensorimotor cortex (S1M1) and the ARAS in both groups was also investigated. Results: Compared with controls, patients showed significantly less rCBF in posterior medial cortices (precuneus) and higher rCBF in ARAS at rest. During stimulation, bilateral Brodmann area 40 was less activated and not functionally correlated to S1M1 in PVS as it was in controls. Precuneus showed a lesser degree of deactivation in patients. Finally, ARAS whose activity was functionally correlated to that of the precuneus in controls was not in PVS. Conclusions: Global neuronal workspace theory predicts that damage to long-distance white matter tracts should impair access to conscious perception. During persistent vegetative state, we identified a hypermetabolism in the ascending reticular activating system (ARAS) and impaired functional connectivity between the ARAS and the precuneus. This result emphasizes the functional link between cortices and brainstem in the genesis of perceptual awareness and strengthens the hypothesis that consciousness is based on a widespread neural network.

Spinal anesthesia using single injection small-dose bupivacaine versus continuous catheter injection techniques for surgical repair of hip fracture in elderly patients.

Aging and disease may make elderly patients particularly susceptible to hypotension during spinal anesthesia. We compared the hemodynamic effect of continuous spinal anesthesia (CSA) and small dose single injection spinal anesthesia (SA) regarding the incidence of hypotension. Seventy-four patients aged >75 yr undergoing surgical repair of hip fracture were randomized into 2 groups of 37 patients each. Group CSA received a continuous spinal anesthetic with a titration of 2.5 mg boluses every 15 min of isobaric bupivacaine, while group SA received a single injection spinal anesthetic with 7.5 mg of isobaric bupivacaine. The overall variations in noninvasive automated arterial blood pressure were not statistically significantly different in the 2 groups at baseline and after CSA or SA (not significant). In the SA group, 68% of patients experienced at least one episode of hypotension (decrease in systolic arterial blood pressure greater than 20% of baseline value) versus 31% of patients in the CSA group (P = 0.005). In the SA group, 51% of patients experienced at least one episode of severe hypotension (decrease in systolic arterial blood pressure more than 30% of baseline value) versus 8% of patients in the CSA group (P < 0.0001). In the CSA group, 4.5 ± 2 mg of ephedrine was injected versus 11 ± 2 mg in the SA group (P = 0.005). In the CSA group, 5 mg (2.5–10) of anesthetic solution was required versus 7.5 mg in the SA group (P < 0.0001). We conclude that, in elderly patients undergoing hip fracture repair, CSA provides fewer episodes of hypotension and severe hypotension compared with a single intrathecal injection of 7.5 mg bupivacaine.

Predictive value of abdominal obesity vs. body mass index for determining risk of intensive care unit mortality.

Objective:To explore whether sagittal abdominal diameter as a marker of abdominal obesity is a risk factor for death and morbidity in patients in the intensive care unit and a better outcome determinant for obese patients than body mass index. Design:Prospective, observational study from April 2008 to January 2009. Setting:Two general intensive care units, both in Toulouse University Hospitals, France. Participants:All adult patients admitted in the two intensive care units except those routinely discharged within 48 hrs or those having conditions with possible effect on anthropometric indices. Interventions:Measurement of the sagittal abdominal diameter at admission allowed us to divide the studied population into abdominally obese, underweight, and control groups. Measurements and Results:The primary outcome measure was mortality in the intensive care unit until day 60 after admission. Secondary outcomes were morbidity and length of stay in the intensive care unit. Among 503 patients admitted, 403 were included. At admission, age, diabetes, dyslipidemia, hypertension, Simplified Acute Physiology Score II, and McCabe scores were higher in the abdominally obese group (n = 109) than in the control group (n = 277). The rate of death was higher in the abdominally obese group compared to control (44% vs. 25.3%; p < .01). After adjustment for age, simplified acute physiology score, II and McCabe score, a multivariate analysis showed an increased risk of death in the abdominally obese group (adjusted odds ratio, 2.12; 95% confidence interval, 1.25–3.60). A body mass index >30 kg/m2 was not an independent risk factor for death. During the stay in the intensive care unit, incidence of acute renal failure and abdominal compartment syndrome were higher in the abdominally obese group. Conclusion:A high sagittal abdominal diameter, and not a high body mass index, is an independent risk factor of death in critically ill patients.

Opioid-induced hyperalgesia in a mice model of orthopaedic pain: preventive effect of ketamine

BACKGROUND The aim of this study was to assess the preventative effect of ketamine on the exaggerated postoperative pain observed in sufentanil-treated mice and its ability to improve the analgesic effectiveness of morphine during the postoperative period in an orthopaedic model of pain. METHODS In this study, we assessed the effects of ketamine on sufentanil enhancement of pain behaviour induced by fracture and the effects of ketamine on postoperative morphine-induced analgesia. Three tests were used to assess pain behaviour: von Frey filament application, hot-plate test, and a subjective pain scale. RESULTS When administered 1 day after surgery in mice treated with sufentanil on D0 (before surgery), morphine induced an analgesic effect as observed by the nociceptive threshold increase in saline- and ketamine-treated mice. Morphine was more effective in ketamine-treated (1 and 50 mg kg(-1)) mice. CONCLUSIONS Our results suggest that pre-emptive use of ketamine is useful in orthopaedic surgery in this mice model to diminish short- and long-term hyperalgesia, but also to improve morphine effectiveness leading to a better mobilization and more rapid rehabilitation.

Stroke output variations calculated by esophageal Doppler is a reliable predictor of fluid response

ObjectiveEsophageal Doppler allows continuous monitoring of stroke volume index (SVI) and corrected flow time (FTc). We hypothesized that variations in stroke output index SOI (SVI/FTc) during volume expansion can predict the hemodynamic response to subsequent fluid loading better than the static values.Design and settingProspective study in the intensive care unit of a university hospital.PatientsFifty-one patients with circulatory failure were monitored by esophageal Doppler.InterventionsPatients who responded to a first fluid challenge received a second one. Patients who responded to both were classified as responders-responders, and those who did not respond to the second as responders-nonresponders. In these two groups we compared ΔSVI, ΔFTc, and ΔSOI during each fluid challenge and also static values at the end of each fluid challenge.Measurements and resultsAfter the first fluid challenge ΔSOI and ΔSVI were significantly higher in patients who responded to subsequent volume expansion than in patients who no longer responded. ROC curves showed that ΔSOI was a better predictor of fluid responsiveness than ΔSVI. During volume expansion a ΔSOI value of 11% discriminated between responders and nonresponders to subsequent volume expansion with a sensitivity of 91% and a specificity of 97%. There was no significant difference between the two groups for FTc value at the end of first fluid challenge.ConclusionsAnalysis of ΔSOI during fluid challenge predicts response to subsequent fluid challenge and FTc is not a reliable indicator of cardiac preload.

Cerebral hemodynamic changes in severe head injury patients undergoing decompressive craniectomy.

Objective: To assess the intracranial hemodynamic modifications induced by a decompressive craniectomy (DC) after severe traumatic brain injury (TBI), using transcranial Doppler (TCD) ultrasonography and intracranial pressure (ICP) sensor. Mortality rate and neurological outcomes were also evaluated after this procedure. Design: A prospective study was carried out on 26 TBI patients, measuring transcranial Doppler and ICP before, immediately after, and 48 hours after the DC, allowing for statistical analysis of hemodynamic changes. The mortality rate and the neurological outcomes were assessed. Measurements and Results: After DC, ICP decreased from 37±17 to 20±13 mm Hg (P=0.0003). The global cerebral blood flow was modified with diastolic velocities rising from 23±15 to 31±13 cm/s (P=0.0038) and a pulsatility index decreasing from 1.70±0.66 to 1.18±0.37 (P=0.0012). This normalization of the global cerebral hemodynamics after the DC was immediate, symmetric, and constant during the first 48 hours. Outcome was evaluated at 6 months: good recovery or moderate disability was observed in 11 patients (42%), persistent vegetative state in 7 patients (27%), and 8 patients died (31%). Conclusions: The DC results in a significant, immediate, and durable improvement of ICP associated with a normalization of cerebral blood flow velocities in most TBI patients with refractory intracranial hypertension.

Integrated Use of Bedside Lung Ultrasound and Echocardiography in Acute Respiratory Failure : A Prospective Observational Study in ICU

BACKGROUND It has been suggested that the complementary use of echocardiography could improve the diagnostic accuracy of lung ultrasonography (LUS) in patients with acute respiratory failure (ARF). Nevertheless, the additional diagnostic value of echocardiographic data when coupled with LUS is still debated in this setting. The aim of the current study was to compare the diagnostic accuracy of LUS and an integrative cardiopulmonary ultrasound approach (thoracic ultrasonography [TUS]) in patients with ARF. METHODS We prospectively recruited patients consecutively admitted for ARF to the ICU of a university teaching hospital over a 12-month period. Inclusion criteria were age ≥ 18 years and the presence of criteria for severe ARF justifying ICU admission. We compared both LUS and TUS approaches and the final diagnosis determined by a panel of experts using machine learning methods to improve the accuracy of the final diagnostic classifiers. RESULTS One hundred thirty-six patients were included (age, 68 ± 15 years; sex ratio, 1). A three-dimensional partial least squares and multinomial logistic regression model was developed and subsequently tested in an independent sample of patients. Overall, the diagnostic accuracy of TUS was significantly greater than LUS (P < .05, learning and test sample). Comparisons between receiver operating characteristic curves showed that TUS significantly improves the diagnosis of cardiogenic edema (P < .001, learning and test samples), pneumonia (P < .001, learning and test samples), and pulmonary embolism (P < .001, learning sample). CONCLUSIONS This study demonstrated for the first time to our knowledge a significantly better performance of TUS than LUS in the diagnosis of ARF. The value of the TUS approach was particularly important to disambiguate cases of hemodynamic pulmonary edema and pneumonia. We suggest that the bedside use of artificial intelligence methods in this setting could pave the way for the development of new clinically relevant integrative diagnostic models.

Ciprofloxacin use in critically ill patients: pharmacokinetic and pharmacodynamic approaches

The objective of this study was to evaluate the properties of ciprofloxacin in intensive care patients using a population approach. Seventy patients received ciprofloxacin. On Day 1, three to eight blood samples were taken over a 12-h period. Peak drug concentration (Cmax) and 24-h area under the concentration-time curve (AUC) were compared with the French breakpoint defining antibiotic susceptibility. A population pharmacokinetic modelling approach was then carried out. A two-compartment open model with a proportional error model best fitted the data. A relationship between the elimination constant rate and the Cockcroft creatinine clearance was found. Ciprofloxacin clearance was 13.6+/-5.8L/h, the volume of distribution was 62.0+/-10.7 L and the ciprofloxacin half-life was 3.7+/-1.8h. When the minimum inhibitory concentration (MIC) was equal to 1mg/L the inhibitory ratio (IR) was > or = 8 in only 10.8% of cases, and the AUC/MIC ratio (AUIC) was 42.0+/-36. In conclusion, this study highlights that the Cockcroft clearance significantly influences ciprofloxacin elimination. Target plasma concentrations for ciprofloxacin, the IR and AUIC were rarely reached with a standard dosing regimen. In critically ill patients, the observed pharmacokinetic variability is mainly responsible for the overly frequent low concentrations of ciprofloxacin, emphasising the need for therapeutic monitoring.