Antonia Blanié

The Limits of Succinylcholine for Critically Ill Patients

BACKGROUND:Urgent tracheal intubations are common in intensive care units (ICU), and succinylcholine is one of the first-line neuromuscular blocking drugs used in these situations. Critically ill patients could be at high risk of hyperkalemia after receiving succinylcholine because one or more etiologic factors of nicotinic receptor upregulation can be present, but there are few data on its real risk. Our objectives in this study were to determine the factors associated with arterial potassium increase (&Dgr;K) and to assess the occurrence of acute hyperkalemia ≥6.5 mmol/L after succinylcholine injection for intubation in the ICU. METHODS:In a prospective, observational study, all critically ill patients intubated with succinylcholine in an ICU were screened. Only intubations with arterial blood gases and potassium measurements before and after (Kafter) a succinylcholine injection were studied. RESULTS:During 18 months, 131 critically ill patients were intubated after receiving succinylcholine with arterial potassium before and after intubation (Kafter) for a total of 153 intubations. After multivariate analysis, the only factor associated with &Dgr;K was the length of ICU stay before intubation (&rgr; = 0.561, P < 0.001). The factors associated with Kafter ≥6.5 mmol/L (n = 11) were the length of ICU stay (P < 0.001) and the presence of acute cerebral pathology (P = 0.047). The threshold of 16 days was found highly predictive of acute hyperkalemia ≥6.5 with 37% (95% confidence interval: 19%–58%) of Kafter ≥6.5 after the 16th day compared with only 1% (95% confidence interval: 0%–4%) of Kafter ≥6.5 when succinylcholine was injected during the first 16 days. CONCLUSIONS:This study shows that the risk of &Dgr;K after succinylcholine injection is strongly associated with the length of ICU stay. The risk of acute hyperkalemia ≥6.5 mmol/L is highly significant after 16 days.

The limited efficacy of tramadol in postoperative patients: a study of ED80 using the continual reassessment method.

BACKGROUND:The aim of this study was to reevaluate the efficacy of tramadol for postoperative analgesia and to determine its ED80 (the clinical dose for which 80% of the patients had their pain adequately relieved) using the Continual Reassessment Method. Because the preliminary results of the first 24 patients were contradictory to the literature, we performed a second trial to verify and validate our data. METHODS:The study was double-blind and prospective. Participants were allocated to a dose of tramadol by 3-patient cohorts, in order of inclusion. The dose of tramadol received in each cohort was determined by the reaction of all previous patients. Five doses were chosen before beginning, with a probability of a positive reaction associated with each: 60 (0.4), 100 (0.55), 140 (0.7), 190 (0.8), and 260 mg (0.9). Tramadol was considered effective if the numeric pain scale was ⩾3/10 at T30. RESULTS:The effective dose in 80% of patients was 260 mg for both trials. The probability of success of the 260 mg dose was 0.699 (95% credibility interval, 0.471–0.874) and 0.657 (95% credibility interval, 0.437–0.853) for trial 1 and trial 2, respectively. CONCLUSION:Tramadol used as a sole drug cannot be considered the drug of choice after moderately painful surgery. The doses needed to relieve pain in 80% of patients are much larger than the usual dose of 100 mg. The Continual Reassessment Method allowed us to determine the ED80 of tramadol with a limited number of patients.

The Frontal Lobe and Thalamus Have Different Sensitivities to Hypoxia-Hypotension after Traumatic Brain Injury: A Microdialysis Study in Rats

After traumatic brain injury (TBI), lesions are anatomically heterogeneous, but the spatial heterogeneity of the post-traumatic brains vulnerability to hypoxia-hypotension (HH) has been poorly studied. Our objective was to compare the effect of HH after TBI on brain energy metabolism into two regions: the frontal lobe and the thalamus. Twenty-eight Sprague-Dawley rats were randomized into four groups: sham, TBI (brain trauma alone, impact acceleration, 450-g weight drop from 1.8 m), HH (blood depletion to mean arterial pressure 40 mm Hg, FiO(2) 10%, 15 min), and TBI-HH (TBI followed by HH, 45-min delay). Cerebral perfusion pressure (CPP) was continuously measured. Brain microdialysis and brain tissue oxygen partial pressure (PtiO(2)) probes were both inserted stereotaxically into the right thalamus and frontal lobe. Except during the HH period, CPP was always above 60 mm Hg. During the hour following the HH period, significant increases in cerebral lactate-pyruvate ratio, glycerol, and glutamate were observed, and were always higher in the frontal lobe than in the thalamus (p<0.001). In the TBI-HH group and in the frontal lobe, increases in glutamate and glycerol were significantly higher than in the HH group (p<0.001). During the 30 min following the HH phase (reperfusion), an increase in PtiO(2) was observed. In the TBI-HH group, this increase was significantly lower in the frontal lobe than in the thalamus. These findings demonstrate that in the early post-traumatic period, the metabolic cerebral response to HH is higher in the frontal lobe than in the thalamus, and is worsened by TBI, suggesting a higher vulnerability for the frontal lobes.

Comparison of learning outcomes between learning roles (spectator and actor) during an immersive simulation.

We have been very interested in the results reported by Boet et al. [1] and we agree that there is a need to formally assess the learning value that students can gain when they are actors during simulation sessions. According to Kolb et al. [2], the concrete experience provided by high fidelity simulation training is the basis for experiential learning. However, in the real world, there is an increasing imbalance between the growing number of undergraduate and postgraduate students and the human

A Comparison of Photoplethysmography Versus Esophageal Doppler for the Assessment of Cardiac Index During Major Noncardiac Surgery.

BACKGROUND:In this prospective observational study, we compared changes in cardiac index (CI) during fluid challenge using photoplethysmography (PPG; Nexfin™) (CIPPG) versus esophageal Doppler (ED) (CIED) in major noncardiac surgery patients. METHODS:Measurements were obtained when the attending anesthesiologist decided to perform a fluid challenge. Correlations with linear regression, Bland-Altman analysis, and analysis of covariance were performed. Trending ability was studied using 2 different methods: a 4-quadrant plot and a polar plot. RESULTS:Forty-three patients were analyzed with a total of 111 fluid challenges. There was a significant linear relationship between CIPPG and CIED (r2 = 0.34; P < 0.001). The bias between the ED and the PPG measurements of CI was −0.114 (95% confidence interval [CI95], −1.9 to 1.7) L/min/m2, with a mean percentage error of 55%. The correlation between the changes in CI during a fluid challenge was significant (r2 = 0.25; P = 0.002). The concordance rate of directional changes (increase or decrease) of CIPPG and CIED during fluid challenge was 67% (CI95, 57–75) for the whole data set and 85% (CI95, 70–94) with an exclusion zone of 15%. When considering ED as a reference, the sensitivity and specificity to give an additional bolus with PPG (increase in CIPPG ≥15%) were 35% (CI95, 19–55) and 90% (CI95, 81–96), respectively, with a positive predictive value of 58% (CI95, 33–80) and a negative predictive value of 78% (CI95, 68–86). CONCLUSIONS:In major noncardiac surgery patients, the evaluation of CI using PPG is not interchangeable with the evaluation of CI using ED. When considering the ED as an accurate device to assess changes in CI, PPG is not appropriate to assess the need for additional fluid administration. These results clearly indicate the limitations of PPG as an accurate device to track changes in CI compared with ED.

Impact of learners’ role (active participant-observer or observer only) on learning outcomes during high-fidelity simulation sessions in anaesthesia: A single center, prospective and randomised study

AIM The increasing use of high-fidelity simulation is limited by the imbalance between the growing number of students and the human resources available in such a way that all residents cannot play a role during scenarios. The learning outcomes of observers need to be studied. METHODS This prospective randomised study was approved by the institutional review board. Anaesthesia residents attending a one-day training session were enrolled. In each of the four scenarios, three residents played an active role while others observed in a separate room. All participants attended debriefing sessions. Residents were randomised between active participant-observer group (AP-O group) and observer group (O group). A similar questionnaire was distributed before, immediately after the session and after three months and included self-reported assessment of satisfaction, medical knowledge (noted 0-16), and non-technical skills. RESULTS A hundred and four questionnaires were analysed. Immediately after the simulation, a significant increase in medical knowledge was recorded but was higher in the AP-O group (6 [5-8] to 10 [8-11]/16) than in the O group (7 [5-8] to 9 [7-10]/16). High scores for non-technical skills were similarly observed in both groups. Satisfaction was high in both groups but was higher in the AP-O group (9 [8-9] versus 8 [8-9]/10, P=0.019). Decay of knowledge was observed for most main outcomes at three months. CONCLUSION This study suggests an immediate improvement of learning outcomes for both roles after immersive simulation but some learning outcomes may be better for residents engaged as players in scenarios.

Left pulmonary artery transection after penetrating thoracic trauma.

We report the case of a stable hemodynamic patient with pulmonary artery transection after penetrating chest trauma. A 39-year-old man was referred to our institution after a penetrating chest injury with a circular saw. His hemodynamic and respiratory status were stable. A left thoracic wound was noted. Hemoglobinemia was 15.3 g/dL. The thoracic computed tomography (CT) scan showed a metal foreign body of 32 mm by 13 mm causing transection of left pulmonary artery with pseudoaneurysm formation (Fig. 1, A to C). There was also a sternal fracture but no pneumothorax or hemothorax. Considering hemodynamic stability, a direct medical transfer to the operating room of our affiliated cardiothoracic center was organized. A bronchial fibroscopy eliminated an associated bronchial lesion. Operation began by median sternotomy incision, and circulatory bypass without aortic clamp was instituted to discharge the right heart. The pleural cavity was then opened and the pulmonary artery dissected. A lesion of the left pulmonary artery with 2 cm parietal defect was observed and treated by pericardial patch (Fig. 1, D). A metal foreign body of 3.5 cm was also extracted and a segmentary artery of the left pulmonary artery was ligatured. No blood transfusion or vasoactive drug was necessary. A control thoracic CT scan showed good perfusion of the pulmonary artery, but a minor left pulmonary embolism treated by anticoagulant. The patient was discharged home on postoperative day 13. Traumatic transaction of the pulmonary artery with pseudoaneurysm formation is rare and often lethal. Most patients die in prehospital or emergency room phase. Others present with hemodynamic instability secondary to massive hemothorax, hemomediastinum, or acute pericardial tamponade. Some exceptional patients presented hemodynamic stability. This can be explained by the low pressure in the pulmonary artery and the local hemostasis provided by the limited extensibility of the mediastinum. Some delayed cases of pseudoaneurysm have been diagnosed 60 years after chest trauma, fortuitously or in thoracic pain, or hemoptysis context.1,2 Usually, after chest trauma, the diagnosis was made by CT scan, sometimes completed by pulmonary angiogram. A bronchial fibroscopy is also necessary to eliminate an associated bronchial lesion. In the acute phase, the risk of rupture with fatal hemorrhage, secondary sepsis, and fistulization is important and immediate surgical treatment is necessary.3,4 In this case, the left pulmonary arterial tear was located in the mediastinal portion of that vessel close to the pulmonary trunk, preventing safe proximal vascular control through left thoracotomy. A median sternotomy was then performed, followed by vascular control under cardiopulmonary bypass, to avoid acute hemorrhage. Simple arterial lacerations may be repaired without pulmonary bypass, but it is required when more extensive injury of the pulmonary artery is suspected. In case of pseudoaneurysm without penetrating trauma, therapeutic abstention or angiographic embolization has been described but secondary surgery was sometimes necessary.1,5–7 In conclusion, traumatic transaction of the pulmonary artery with pseudoaneurysm formation after penetrating trauma can present with variable hemodynamic status, but a surgical treatment is urgent.