Wolfgang Studer

Rocuronium versus succinylcholine for rapid sequence induction of anesthesia and endotracheal intubation: a prospective, randomized trial in emergent cases

When anesthesia is induced with propofol in elective cases, endotracheal intubation conditions are not different between succinylcholine and rocuronium approximately 60 s after the injection of the neuromuscular relaxant. In the present study, we investigated whether, in emergent cases, endotracheal intubation conditions obtained at the actual moment of intubation under succinylcholine differ from those obtained 60 s after the injection of rocuronium. One-hundred-eighty adult patients requiring rapid sequence induction of anesthesia for emergent surgery received propofol (1.5 mg/kg) and either rocuronium (0.6 mg/kg; endotracheal intubation 60 s after injection) or succinylcholine (1 mg/kg; endotracheal intubation as soon as possible). The time from beginning of the induction until completion of the intubation was shorter after the administration of succinylcholine than after rocuronium (median time 95 s versus 130 s; P < 0.0001). Endotracheal intubation conditions, rated with a 9-point scale, were better after succinylcholine administration than after rocuronium (8.6 ± 1.1 versus 8.0 ± 1.5; P < 0.001). There was no significant difference in patients with poor intubation conditions (7 versus 12) or in patients with failed first intubation attempt (4 versus 5) between the groups. We conclude that during rapid sequence induction of anesthesia in emergent cases, succinylcholine allows for a more rapid endotracheal intubation sequence and creates superior intubation conditions compared with rocuronium.

Randomized Comparison of Sevoflurane Versus Propofol to Reduce Perioperative Myocardial Ischemia in Patients Undergoing Noncardiac Surgery

Background— Volatile anesthetics provide myocardial preconditioning in coronary surgery patients. We hypothesized that sevoflurane compared with propofol reduces the incidence of myocardial ischemia in patients undergoing major noncardiac surgery. Methods and Results— We enrolled 385 patients at cardiovascular risk in 3 centers. Patients were randomized to maintenance of anesthesia with sevoflurane or propofol. We recorded continuous ECG for 48 hours perioperatively, measured troponin T and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) on postoperative days 1 and 2, and evaluated postoperative delirium by the Confusion Assessment Method. At 6 and 12 months, we contacted patients by telephone to assess major adverse cardiac events. The primary end point was a composite of myocardial ischemia detected by continuous ECG and/or troponin elevation. Additional end points were postoperative NT-proBNP concentrations, major adverse cardiac events, and delirium. Patients and outcome assessors were blinded. We tested dichotomous end points by &khgr;2 test and NT-proBNP by Mann–Whitney test on an intention-to-treat basis. Myocardial ischemia occurred in 75 patients (40.8%) in the sevoflurane and 81 (40.3%) in the propofol group (relative risk, 1.01; 95% confidence interval, 0.78–1.30). NT-proBNP release did not differ across allocation on postoperative day 1 or 2. Within 12 months, 14 patients (7.6%) suffered a major adverse cardiac event after sevoflurane and 17 (8.5%) after propofol (relative risk, 0.90; 95% confidence interval, 0.44–1.83). The incidence of delirium did not differ (11.4% versus 14.4%; P=0.379). Conclusions— Compared with propofol, sevoflurane did not reduce the incidence of myocardial ischemia in high-risk patients undergoing major noncardiac surgery. The sevoflurane and propofol groups did not differ in postoperative NT-proBNP release, major adverse cardiac events at 1 year, or delirium. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00286585.

High incidence of intravenous thrombi after short-term central venous catheterization of the internal jugular vein

STUDY OBJECTIVE To assess incidence and characteristics of intravenous (i.v.) thrombi associated with short-term central venous catheterization through the internal jugular vein. DESIGN Prospective clinical study. SETTING University hospital. PATIENTS 81 patients undergoing cardiac surgery. INTERVENTIONS A triple-lumen central venous catheter was inserted into the right internal jugular vein immediately before surgery and removed 3 to 4 days later. Heparin at an i.v. dose of 15,000 IU/24 hours was started 6 hours after surgery and continued until the first postoperative morning, followed by subcutaneous low molecular weight heparin 5,000 IU/day in combination with oral aspirin 100 mg/day. MEASUREMENTS AND MAIN RESULTS Anatomy of the internal jugular vein and i.v. blood flow were studied using two-dimensional and color Doppler ultrasonography before insertion of the catheter and after its removal. Thrombi were found in 45 patients (56%). Twenty-five of these thrombi (56%) had the shape of a sleeve, and 20 thrombi (44%) were compact. Length of the thrombi was 1.4 +/- 0.8 cm (mean +/- SD). Half of the thrombi floated with venous blood flow and half were stable. Neither impaired venous blood flow nor clinical signs of embolism or sepsis was found. Follow-up studies in eight patients revealed that the thrombi had not disappeared 5 days after removal of the catheter but had become smaller. CONCLUSION The incidence of i.v. thrombi associated with short-term catheterization of the internal jugular vein was high despite prophylactic anticoagulation. This finding reaffirms the importance of removing central venous catheters as soon as clinically possible. Additional studies using specific outcome tests are needed to thoroughly assess the clinical importance of this finding.

Competence of the internal jugular vein valve is damaged by cannulation and catheterization of the internal jugular vein.

Background Experimental results suggest that the competence of the internal jugular vein (IJV) valve may be damaged when the IJV is cannulated for insertion of a central venous catheter. It has further been hypothesized that the risk of causing incompetence of the proximally located valve might be reduced by using a more distal site for venous cannulation. The present study evaluated these hypotheses in surgical patients. Methods Ninety-one patients without preexisting incompetence of the IJV valve were randomly assigned to undergo distal or proximal IJV cannulation (≥ 1 cm above or below the cricoid level, respectively). Color Doppler ultrasound was used to study whether new valvular incompetence was present during Valsalva maneuvers after insertion of a central venous catheter, immediately after removal of the catheter, and, in a subset of patients, several months after catheter removal, when compared with baseline findings before cannulation of the IJV. Results Incompetence of the IJV valve was frequently induced both by proximal and distal cannulation and catheterization of the IJV. Its incidence was higher after proximal than after distal cannulation (76%vs. 41%;P < 0.01) and tended to be so after removal of the catheter (47%vs. 28%;P = 0.07). Valvular incompetence persisting immediately after removal of the catheter did not recover within 8–27 months in most cases. Conclusions Cannulation and catheterization of the IJV may cause persistent incompetence of the IJV valve. Choosing a more distal site for venous cannulation may slightly lower the risk of causing valvular incompetence but does not reliably avoid it.

Occlusive mesenteric ischemia and its effects on jejunal intramucosal pH, mesenteric oxygen consumption and oxygen tensions from surfaces of the jejunum in anesthetized pigs

AbstractObjective: To investigate the effects of superior mesenteric artery (SMA) flow reduction on the jejunal intramucosal pH (pHi) and to compare these effects with corresponding changes of mesenteric oxygen transport variables and oxygen tensions on the surfaces of the jejunal serosa and mucosa. Design: Prospective, randomized, controlled, experimental study. Setting: Animal research laboratory. Subjects: 20 domestic pigs. Interventions: Mechanical flow reduction in the SMA. The animals were randomized to have an SMA flow of 0%, 25%, 38%, 50% or 100% (control). Measurements and main results: Measurements (baseline, ischemia, reperfusion) consisted of hemodynamic and oxygen transport variables, SMA blood flow, mesenteric oxygen transport variables, pHi and oxygen tensions of the jejunal serosa and mucosa. Flow reduction in the SMA resulted in a significant decrease of pHi indicating ischemia earlier than mesenteric oxygen transport variables. The relationship between mesenteric oxygen delivery (DO2ms) and pHi during acute ischemia is best described by a sigmoid curve. There was a linear correlation between the changes of the jejunal surface oxygen tensions and pHi due to SMA flow reduction. Conclusion: The sigmoid relationship between pHi and DO2ms indicated that pHi is a sensitive parameter for detecting ischemia at 50% of the baseline oxygen delivery and that below 25% there was no further decrease of pHi. In contrast, mesenteric and whole body oxygen transport parameters were not indicative of impaired mucosal oxygen supply.

Aortic Cross-Clamping and Reperfusion in Pigs Reduces Microvascular Oxygenation by Altered Systemic and Regional Blood Flow Distribution

BACKGROUND: In this study, we tested the hypothesis that aortic cross-clamping (ACC) and reperfusion cause distributive alterations of oxygenation and perfusion in the microcirculation of the gut and kidneys despite normal systemic hemodynamics and oxygenation. METHODS: Fifteen anesthetized pigs were randomized between an ACC group (n = 10), undergoing 45 minutes of aortic clamping above the superior mesenteric artery, and a time-matched sham surgery control group (n = 5). Systemic, intestinal, and renal hemodynamics and oxygenation variables were monitored during 4 hours of reperfusion. Microvascular oxygen partial pressure (&mgr;PO2) was measured in the intestinal serosa and mucosa and the renal cortex, using the Pd-porphyrin phosphorescence technique. Intestinal luminal PCO2 was determined by air tonometry and the serosal microvascular flow by orthogonal polarization spectral imaging. RESULTS: Organ blood flow and renal and intestinal &mgr;PO2 decreased significantly during ACC, whereas the intestinal oxygen extraction and PCO2 gap increased. The intestinal response to reperfusion after ACC was a sustained reactive hyperemia but no such effect was seen in the kidney. Despite a sustained high intestinal O2 delivery, serosal &mgr;PO2 (median [range], 49 mm Hg [41–67 mm Hg] versus 37 mm Hg [27–41 mm Hg]; P < 0.05 baseline versus 4 hours reperfusion) and the absolute number of perfused microvessels decreased along with an increased intestinal PCO2 gap (17 mm Hg [10–19 mm Hg] versus 23 mm Hg [19–30 mm Hg]; P < 0.05). In contrast, the kidney showed a progressive O2 delivery decrease accompanied by a decrease in renal cortex oxygenation (70 mm Hg [52–93 mm Hg] versus 57 mm Hg [33–64 mm Hg]; P < 0.05). CONCLUSION: Increased systemic and regional blood flow and oxygen supply after ACC does not ensure adequate regional blood flow and microcirculatory oxygenation in all organs.

Resuscitation from cardiac arrest with adrenaline/epinephrine or vasopressin: effects on intestinal mucosal tonometer pCO2 during the postresuscitation period in rats

BACKGROUND The use of vasopressin instead of adrenaline/epinephrine during resuscitation improves vital organ perfusion, but the effects on mesenteric perfusion following successful resuscitation are not fully evaluated. The present study was designed to compare the effects of vasopressin and adrenaline/epinephrine, given to rats during resuscitation from ventricular fibrillation, on to mesenteric ischaemia, as determined by intestinal mucosal tonometer pCO(2) during the postresuscitation period. METHODS AND RESULTS Male Sprague-Dawley rats (n=28) were allocated randomly to receive vasopressin (0.8 U/kg) or adrenaline/epinephrine (90 microg/kg) after 5 min of ventricular fibrillation. Precordial chest compression was initiated 4 min after the start of ventricular fibrillation, continued for 4 min, and followed by defibrillation. Seven of 14 (vasopressin) and 12 of 14 (adrenaline/epinephrine) rats were successfully defibrillated (P=0.10, Fishers exact test) and observed for 60 min. Intestinal mucosal tonometer pCO(2) measurements before cardiac arrest and 15, 30, and 60 min following return of spontaneous circulation were 47+/-3, 73+/-8, 63+/-7, and 56+/-6 mmHg in the vasopressin group and 48+/-5, 78+/-7, 67+/-6, and 62+/-6 mmHg in the adrenaline/epinephrine group (P<0.05 at 60 min between vasopressin and adrenaline/epinephrine). Right atrial hemoglobin oxygen saturations at these time points were 73+/-5, 51+/-12, 58+/-11, and 63+/-5% in the vasopressin group and 76+/-7, 44+/-10, 52+/-10 and 54+/-8% in the adrenaline/epinephrine group (P<0.05 at 60 min between vasopressin and adrenaline/epinephrine). CONCLUSIONS We conclude that in this rat model the administration of vasopressin instead of adrenaline/epinephrine for CPR tends to be associated with lower resuscitation success, but less mesenteric ischaemia during the postresuscitation period in successfully resuscitated rats.

0.5% Versus 1.0% 2-chloroprocaine for Intravenous Regional Anesthesia: A Prospective, Randomized, Double-blind Trial

In this randomized prospective double-blind study we tested the hypothesis that compared with 40 mL chloroprocaine 0.5%, 40 mL chloroprocaine 1% results in an earlier onset to analgesia duration and improves distal tourniquet tolerance in 150 patients undergoing forearm surgery under IV regional anesthesia using a double-cuff technique, switching from the proximal to the distal cuff was performed if pain scores increased above 4 of 10. Switching to the distal cuff resulted in pain scores below 4 in 69% of patients in the 0.5% group and in 88% of patients in the 1% group (P = 0.047). In addition, both groups differed in the sustained effect on distal tourniquet pain (P = 0.020). Time between injection and onset to analgesia duration was 13 ± 1 min in the 0.5% group and 11 ± 1 min in the 1% group (P = 0.0006). On release of the tourniquet, signs of systemic local anesthetic toxicity occurred in 6 patients of the 0.5% group and 28 of the 1% group (P < 0.0001). We conclude that chloroprocaine 1% resulted in an earlier onset of analgesia and improved distal tourniquet tolerance. However, these beneficial effects must be weighed against a fourfold increase in side effects.

Ileocecal Valve as Substitute for the Missing Pyloric Sphincter After Partial Distal Gastrectomy

ObjectivesAccelerated gastric emptying (including dumping syndrome) occurs frequently after gastric resections, largely resulting from rapid entry of meal contents into the small intestine. The authors hypothesized that an ileocecal segment used as an interpositional graft placed between the remaining part of the stomach and the small intestine would slow down food transit and thus replace pyloric function. MethodsThirty Göttingen minipigs were randomized into three groups. Group 1: partial gastrectomy and Roux-en-Y reconstruction; Group 2: partial gastrectomy and ileocecal interpositional graft; and Group 3: sham laparotomy. Gastric emptying in the nonsedated animals was quantified using radioscintigraphy at 3 and 6 months postoperatively. The animals ingested 300 grams of soft food containing 99mTc labeled resin- pellets using a technique previously described. Data were analyzed using ANOVA. ResultsThree months postoperatively, the ileocecal group had a significantly prolonged gastric emptying time compared with the Roux-en-Y group, but gastric emptying time was also significantly faster compared to the control group (sham laparotomy). After 6 months no significant difference was seen between the ileocecal group and the controls, while emptying rates were still significantly faster in the Roux-en-Y group. ConclusionsReconstruction of the gastric reservoir with an ileocecal segment largely restores gastric emptying patterns of food in minipigs. Six months postoperatively, gastric emptying time is similar to that of controls, and significantly slower when compared with the group with Roux-en-Y reconstruction. These results suggest that the ileocecal interposition graft could offer specific advantages over current reconstruction procedures.

Systemic and mesenteric hemodynamics, metabolism, and intestinal tonometry in a rat model of supraceliac aortic cross-clamping and declamping☆

OBJECTIVE To describe systemic and mesenteric hemodynamics, metabolism, and intestinal tonometry in a rat model of supraceliac aortic cross-clamping and declamping. DESIGN Prospective, randomized, experimental study. SETTING University cardiovascular research laboratory. PARTICIPANTS Twelve male anesthetized and ventilated Sprague-Dawley rats. INTERVENTION Supraceliac aortic cross-clamping was performed for 30 minutes, followed by declamping and reperfusion for 180 minutes or sham clamping and sham declamping. MEASUREMENTS AND MAIN RESULTS Mean arterial blood pressure; abdominal aortic, superior mesenteric, and carotid artery blood flow; intestinal mucosal tonometry; hemoglobin; lactate; and blood gases were measured before and after 30 minutes of aortic cross-clamping and 15, 30, 60, 120, and 180 minutes after declamping during reperfusion. Aortic cross-clamping induced an increase in mean arterial pressure (117+/-20 mm Hg to 147+/-12 mm Hg), an increase in right atrial hemoglobin saturation(66%+/-11% to 81%+/-6%), an increase in lactate levels (1.7+/-0.7 mmol/L to 4.3+/-1.3 mmol/L), and an increase in tonometric PCO2 (49.6+/-5.0 mm Hg to 75.6+/-8.6 mm Hg). Three hours of reperfusion after declamping resulted in significantly decreased mean arterial pressure (38+/-10 mm Hg); decreased aortic (101+/-12 mL/min/kg to 57+/-32 mL/min/kg), mesenteric (19+/-4 to 13+/-6 mL/min/kg), and carotid (12+/-4 mL/min/kg to 5+/-3 mL/min/ kg) blood flows; and elevated lactate levels (4.2+/-2.0 mmol/L). Tonometric PCO2 had normalized to baseline levels (51.9+/-3.8 mm Hg), but PCO2 gap was significantly higher than in sham clamped rats (17.9+/-7.8 mm Hg v. 7.0+/-2.6 mm Hg). CONCLUSIONS Hemodynamic and metabolic effects of aortic cross-clamping and declamping known from large animal models are reproducible using a rat model. Intestinal tonometry indicated mesenteric ischemia during aortic cross-clamping, which was reversible to preclamp values within 30 minutes of reperfusion after declamping.