Background It is speculated that opioid-free anesthesia may provide adequate pain control while reducing postoperative opioid consumption. However, there is currently no evidence to support the speculation. The authors hypothesized that opioid-free balanced anesthetic with dexmedetomidine reduces postoperative opioid-related adverse events compared with balanced anesthetic with remifentanil. Methods Patients were randomized to receive a standard balanced anesthetic with either intraoperative remifentanil plus morphine (remifentanil group) or dexmedetomidine (opioid-free group). All patients received intraoperative propofol, desflurane, dexamethasone, lidocaine infusion, ketamine infusion, neuromuscular blockade, and postoperative lidocaine infusion, paracetamol, nefopam, and patient-controlled morphine. The primary outcome was a composite of postoperative opioid-related adverse events (hypoxemia, ileus, or cognitive dysfunction) within the first 48 h after extubation. The main secondary outcomes were episodes of postoperative pain, opioid consumption, and postoperative nausea and vomiting. Results The study was stopped prematurely because of five cases of severe bradycardia in the dexmedetomidine group. The primary composite outcome occurred in 122 of 156 (78%) dexmedetomidine group patients compared with 105 of 156 (67%) in the remifentanil group (relative risk, 1.16; 95% CI, 1.01 to 1.33; P = 0.031). Hypoxemia occurred 110 of 152 (72%) of dexmedetomidine group and 94 of 155 (61%) of remifentanil group patients (relative risk, 1.19; 95% CI, 1.02 to 1.40; P = 0.030). There were no differences in ileus or cognitive dysfunction. Cumulative 0 to 48 h postoperative morphine consumption (11 mg [5 to 21] versus 6 mg [0 to 17]) and postoperative nausea and vomiting (58 of 157 [37%] versus 37 of 157 [24%]; relative risk, 0.64; 95% CI, 0.45 to 0.90) were both less in the dexmedetomidine group, whereas measures of analgesia were similar in both groups. Dexmedetomidine patients had more delayed extubation and prolonged postanesthesia care unit stay. Conclusions This trial refuted the hypothesis that balanced opioid-free anesthesia with dexmedetomidine, compared with remifentanil, would result in fewer postoperative opioid-related adverse events. Conversely, it did result in a greater incidence of serious adverse events, especially hypoxemia and bradycardia. Editor’s Perspective What We Already Know about This Topic It is hoped but not proven that opioid-free anesthesia provides adequate postoperative analgesia and reduced opioid-related side effects Dexmedetomidine is sometimes used to replace opioids in balanced opioid-free anesthetics What This Article Tells Us That Is New In a randomized, blinded, multicenter trial, study patients undergoing noncardiac surgery received a standard anesthetic featuring lidocaine and ketamine, plus either remifentanil or an alternative anesthetic where dexmedetomidine was substituted for remifentanil The primary outcome, composed of postoperative hypoxemia, ileus, and cognitive dysfunction, was more common among patients receiving opioid-free anesthesia Importantly, opioid-free anesthesia with dexmedetomidine was associated with severe bradycardia, and the study was terminated early for that reason

Background: Diaphragm and psoas are affected during sepsis in animal models. Whether diaphragm or limb muscle is preferentially affected during sepsis in the critically ill remains unclear. Methods: Retrospective secondary analysis study including 40 patients, comparing control (n = 17) and critically ill patients, with (n = 14) or without sepsis (n = 9). Diaphragm volume, psoas volume, and cross-sectional area of the skeletal muscles at the third lumbar vertebra were measured during intensive care unit (ICU) stay using tridimensional computed tomography scan volumetry. Diaphragm strength was evaluated using magnetic phrenic nerve stimulation. The primary endpoint was the comparison between diaphragm and peripheral muscle volume kinetics during the ICU stay among critically ill patients, with or without sepsis. Results: Upon ICU admission, neither diaphragm nor psoas muscle volumes were significantly different between critically ill and control patients (163 ± 53 cm 3 vs. 197 ± 82 cm 3 for the diaphragm, P = 0.36, and 272 ± 116 cm 3 vs. to 329 ± 166 cm 3 for the psoas, P = 0.31). Twenty-five (15 to 36) days after admission, diaphragm volume decreased by 11 ± 13% in nonseptic and by 27 ± 12% in septic patients, P = 0.01. Psoas volume decreased by 11 ± 10% in nonseptic and by 19 ± 13% in septic patients, P = 0.09. Upon ICU admission, diaphragm strength was correlated with diaphragm volume and was lower in septic (6.2 cm H 2 O [5.6 to 9.3]) than that in nonseptic patients (13.2 cm H 2 O [12.3 to 15.6]), P = 0.01. Conclusions: During the ICU stay, both diaphragm and psoas volumes decreased. In septic patients, the authors report for the first time in humans preferential diaphragm atrophy compared with peripheral muscles.

Background: Intellivent is a new full closed-loop controlled ventilation that automatically adjusts both ventilation and oxygenation parameters. The authors compared gas exchange and breathing pattern variability of Intellivent and pressure support ventilation (PSV). Methods: In a prospective, randomized, single-blind design crossover study, 14 patients were ventilated during the weaning phase, with Intellivent or PSV, for two periods of 24 h in a randomized order. Arterial blood gases were obtained after 1, 8, 16, and 24 h with each mode. Ventilatory parameters were recorded continuously in a breath-by-breath basis during the two study periods. The primary endpoint was oxygenation, estimated by the calculation of the difference between the Pa o 2 /F io 2 ratio obtained after 24 h of ventilation and the Pa o 2 /F io 2 ratio obtained at baseline in each mode. The variability in the ventilatory parameters was also evaluated by the coefficient of variation (SD to mean ratio). Results: There were no adverse events or safety issues requiring premature interruption of both modes. The Pa o 2 /F io 2 (mean ± SD) ratio improved significantly from 245 ± 75 at baseline to 294 ± 123 ( P = 0.03) after 24 h of Intellivent. The coefficient of variation of inspiratory pressure and positive end-expiratory pressure (median [interquartile range]) were significantly higher with Intellivent, 16 [11–21] and 15 [7–23]%, compared with 6 [5–7] and 7 [5–10]% in PSV. Inspiratory pressure, positive end-expiratory pressure, and F io 2 changes were adjusted significantly more often with Intellivent compared with PSV. Conclusions: Compared with PSV, Intellivent during a 24-h period improved the Pa o 2 /F io 2 ratio in parallel with more variability in the ventilatory support and more changes in ventilation settings.

Background : Assessment and management of septic shock associated adrenal function remain controversial. The aim of this study was to explore the prognostic value of adrenal gland volume in adults with septic shock. Methods : A short cosyntropin test and determination of adrenal volume by computed tomography were performed within 48 h of shock in patients with septic shock (n = 184) and in 2 control groups: 40 ambulatory patients and 15 nonseptic critically ill patients. The primary endpoint was intensive care unit mortality. Results : At intensive care unit discharge, 59 patients with septic shock died. Adrenal volume was 12.5 cm [95% CI, 11.3-13.3] and 8 cm [95% CI, 6.8-10.1] in the nonseptic group (P < 0.05 with both septic cohorts) and 7.2 cm [95%CI, 6.3-8.5] in the ambulatory patient group (P < 0.05 in patients with septic shock). In patients with septic shock, adrenal volume less than 10 cm was associated with higher 28-day mortality rates with an area under the receiver operating curve of 0.84 [95% CI, 0.78-0.89]. Adrenal volume above 10 cm was an independent predictor of intensive care unit survival (hazard ratio = 0.014; 95% CI [0.004-0.335]). Conclusion : A total adrenal gland volume less than 10 cm during septic shock was associated in univariate and multivariate analysis with mortality at day 28 in patients with septic shock. Whether adrenal gland volume can be a surrogate of adrenal gland function and used to guide hydrocortisone therapy in septic shock patients needs to be further investigated.

Background Morbid obesity predisposes patients to lung collapse and hypoxemia during induction of anesthesia. The aim of this prospective study was to determine whether noninvasive positive pressure ventilation (NPPV) improves arterial oxygenation and end-expiratory lung volume (EELV) compared with conventional preoxygenation, and whether NPPV followed by early recruitment maneuver (RM) after endotracheal intubation (ETI) further improves oxygenation and respiratory function compared with NPPV alone. Methods Sixty-six consecutive patients (body mass index, 46 ± 6 kg/m²) were randomized to receive 5 min of either conventional preoxygenation with spontaneous breathing of 100% O₂ (CON), NPPV (pressure support and positive end-expiratory pressure), or NPPV followed by RM (NPPV+RM). Gas exchange was measured in awake patients, at the end of preoxygenation, immediately after ETI, and 5 min after the onset of mechanical ventilation. EELV was measured immediately after ETI and 5 min after mechanical ventilation. The primary endpoint was arterial oxygenation 5 min after the onset of mechanical ventilation. Results are presented as mean ± SD. Results At the end of preoxygenation, Pao₂ was higher in the NPPV and NPPV+RM groups (382 ± 87 mmHg and 375 ± 82 mmHg, respectively; both P < 0.001) compared with the CON group (306 ± 51 mmHg) and remained higher after ETI (225 ± 104 mmHg and 221 ± 110 mmHg, in the NPPV and NPPV+RM groups, respectively; both P < 0.01 compared with the CON group [150 ± 50 mmHg]). After the onset of mechanical ventilation, Pao₂ was 93 ± 25 mmHg in the CON group, 128 ± 54 mmHg in the NPPV group (P = 0.035 vs. CON group), and 234 ± 73 mmHg in the NPPV+RM group (P < 0.0001 vs. NPPV group). After ETI, EELV was higher in the NPPV group compared with the CON group (P < 0.001). Compared with NPPV alone, RM further improved gas exchange and EELV (all P < 0.05). A significant correlation was found between Pao2 obtained 5 min after mechanical ventilation and EELV (R = 0.41, P < 0.001). Conclusion NPPV improves oxygenation and EELV in morbidly obese patients compared with conventional preoxygenation. NPPV combined with early RM is more effective than NPPV alone at improving respiratory function after ETI.

Background Pulmonary function is impaired during pneumoperitoneum mainly as a result of atelectasis formation. We studied the effects of 10 cm H2O of positive end-expiratory pressure (PEEP) and PEEP followed by a recruitment maneuver (PEEP+RM) on end-expiratory lung volume (EELV), oxygenation and respiratory mechanics in patients undergoing laparoscopic surgery. Methods Sixty consecutive adult patients (30 obese, 30 healthy weight) in reverse Trendelenburg position were prospectively studied. EELV, static elastance of the respiratory system, dead space, and gas exchange were measured before and after pneumoperitoneum insufflation with zero end-expiratory pressure, with PEEP alone, and with PEEP+RM. Results are presented as mean ± SD. Results Pneumoperitoneum reduced EELV (healthy weight, 1195 ± 405 vs. 1724 ± 774 ml; obese, 751 ± 258 vs. 886 ± 284 ml) and worsened static elastance and dead space in both groups (in all P < 0.01 vs. zero-end expiratory pressure before pneumoperitoneum) whereas oxygenation was unaffected. PEEP increased EELV (healthy weight, 570 ml, P < 0.01; obese, 364 ml, P < 0.01) with no effect on oxygenation. Compared with PEEP alone, EELV and static elastance were further improved after RM in both groups (P < 0.05), as was oxygenation (P < 0.01). In all patients, RM-induced change in EELV was 16% (P = 0.04). These improvements were maintained 30 min after RM. RM-induced changes in EELV correlated with change in oxygenation (r = 0.42, P < 0.01). Conclusion RM combined with 10 cm H2O of PEEP improved EELV, respiratory mechanics, and oxygenation during pneumoperitoneum whereas PEEP alone did not.

Background Neurally adjusted ventilatory assist (NAVA) is a new mode of mechanical ventilation that delivers ventilatory assist in proportion to the electrical activity of the diaphragm. This study aimed to compare the ventilatory and gas exchange effects between NAVA and pressure support ventilation (PSV) during the weaning phase of critically ill patients who required mechanical ventilation subsequent to surgery. Methods Fifteen patients, the majority of whom underwent abdominal surgery, were enrolled. They were ventilated with PSV and NAVA for 24 h each in a randomized crossover order. The ventilatory parameters and gas exchange effects produced by the two ventilation modes were compared. The variability of the ventilatory parameters was also evaluated by the coefficient of variation (SD to mean ratio). Results Two patients failed to shift to NAVA because of postoperative bilateral diaphragmatic paralysis, and one patient interrupted the study because of worsening of his sickness. In the other 12 cases, the 48 h of the study protocol were completed, using both ventilation modes, with no signs of intolerance or complications. The Pao2/Fio2 (mean ± SD) ratio in NAVA was significantly higher than with PSV (264 ± 71 vs. 230 ± 75 mmHg, P < 0.05). Paco2 did not differ significantly between the two modes. The tidal volume (median [interquartile range]) with NAVA was significantly lower than with PSV (7.0 [6.4-8.6] vs. 6.5 [6.3-7.4] ml/kg predicted body weight, P < 0.05).Variability of insufflation airway pressure, tidal volume, and minute ventilation were significantly higher with NAVA than with PSV. Electrical activity of the diaphragm variability was significantly lower with NAVA than with PSV. Conclusions Compared with PSV, respiratory parameter variability was greater with NAVA, probably leading in part to the significant improvement in patient oxygenation.

Background Contrary to adaptive support ventilation (ASV), prolonged totally controlled mechanical ventilation (CMV) results in the absence of diaphragm activity and causes ventilator-induced diaphragmatic dysfunction. Because maintaining respiratory muscles at rest is likely a major cause of ventilator-induced diaphragmatic dysfunction, ASV may prevent its occurrence in comparison with CMV. The aim of our study was to compare the effects of ASV with those of CMV on both in vivo and in vitro diaphragmatic properties. Methods Two groups of six anesthetized piglets were ventilated during a 72-h period. Piglets in the CMV group (n = 6) were ventilated without spontaneous ventilation, and piglets in the ASV group (n = 6) were ventilated with spontaneous breaths. Transdiaphragmatic pressure was measured after bilateral, supramaximal transjugular stimulation of the two phrenic nerves. A pressure-frequency curve was drawn after stimulation from 20 to 120 Hz of the phrenic nerves. Diaphragm fiber proportions and mean sectional area were evaluated. Results After 72 h of ventilation, transdiaphragmatic pressure decreased by 30% of its baseline value in the CMV group, whereas it did not decrease in the ASV group. Although CMV was associated with an atrophy of the diaphragm (evaluated by mean cross-sectional area of both the slow and fast myosin chains), atrophy was not detected in the ASV group. Conclusion Maintaining diaphragmatic contractile activity by using the ASV mode may protect the diaphragm against the deleterious effect of prolonged CMV, as demonstrated both in vitro and in vivo, in healthy piglets.

Background Critically ill patients frequently experience pain, but assessment rates remain below 40% in mechanically ventilated patients. Whether pain assessment affects patient outcomes is largely unknown. Methods As part of a prospective cohort study of mechanically ventilated patients who received analgesia on day 2 of their stay in the intensive care unit (ICU), the investigators performed propensity-adjusted score analysis to compare the duration of ventilator support and duration of ICU stay between 513 patients who were assessed for pain and 631 patients who were not assessed for pain. Results Patients assessed for pain on day 2 were more likely to receive sedation level assessment, nonopioids, and dedicated analgesia during painful procedures than patients whose pain was not assessed. They also received fewer hypnotics and lower daily doses of midazolam. Patients with pain assessment had a shorter duration of mechanical ventilation (8 vs. 11 days; P < 0.01) and a reduced duration of stay in the ICU (13 vs. 18 days; P < 0.01). In propensity-adjusted score analysis, pain assessment was associated with increased odds of weaning from the ventilator (odds ratio, 1.40; 95% confidence interval, 1.00-1.98) and of discharge from the ICU (odds ratio, 1.43; 95% confidence interval, 1.02-2.00). Conclusions Pain assessment in mechanically ventilated patients is independently associated with a reduction in the duration of ventilator support and of duration of ICU stay. This might be related to higher concomitant rates of sedation assessments and a restricted use of hypnotic drugs when pain is assessed.

Background The authors conducted a patient-based survey of practices to fully describe the assessment and the management of pain and sedation of a large cohort of mechanically ventilated patients during their first week of intensive care unit (ICU) stay. Methods A total of 1,381 adult patients were included in a prospective, observational study in 44 ICUs in France. Pain and sedation assessment, analgesic and sedative use, and analgesic management during procedural pain were collected on days 2, 4, and 6 of the ICU stay. Results The observed rates of assessment on day 2 for sedation (43%) and analgesia (42%) were significantly smaller than that of use of sedatives (72%) and opioids (90%), also noted on days 4 and 6. The use of protocols/guidelines for sedation/analgesia in the ICU reduced the proportion of patients who were treated, although not evaluated. A large proportion of assessed patients were in a deep state of sedation (40-50%). Minor changes in the dosages of the main prescribed agents for sedation (midazolam, propofol) and analgesia (sufentanil, fentanyl, morphine, remifentanil) were found across 6 days of the patient's ICU stay. Procedural pain was specifically managed for less than 25% of patients; during those procedures, the proportion of patients with pain significantly increased from the baseline pain evaluation. Conclusions Excessively deep states of sedation and a lack of analgesia during painful procedures must be prevented. To facilitate systematic pain and sedation assessment and to adjust daily drug dosages accordingly, it seems crucial to promote educational programs and elaboration of protocols/guidelines in the ICU.