Estimation of Arterial Carbon Dioxide Based on End-Tidal Gas Pressure and Oxygen Saturation.

Arterial blood gas (ABG) analysis is the traditional method for measuring the partial pressure of carbon dioxide. In mechanically ventilated patients a continuous noninvasive monitoring of carbon dioxide would obviously be attractive. In the current study, we present a novel formula for noninvasive estimation of arterial carbon dioxide. Eighty-one datasets were collected from 19 anesthetized and mechanically ventilated pigs. Eleven animals were mechanically ventilated without interventions. In the remaining eight pigs the partial pressure of carbon dioxide was manipulated. The new formula (Formula 1) is PaCO2 = PETCO2 + k(PETO2 - PaO2) where PaO2 was calculated from the oxygen saturation. We tested the agreements of this novel formula and compared it to a traditional method using the baseline PaCO2 - ETCO2 gap added to subsequently measured, end-tidal carbon dioxide levels (Formula 2). The mean difference between PaCO2 and calculated carbon dioxide (Formula 1) was 0.16 kPa (±SE 1.17). The mean difference between PaCO2 and carbon dioxide with Formula 2 was 0.66 kPa (±SE 0.18). With a mixed linear model excluding cases with cardiorespiratory collapse, there was a significant difference between formulae (p < 0.001), as well as significant interaction between formulae and time (p < 0.001). In this preliminary animal study, this novel formula appears to have a reasonable agreement with PaCO2 values measured with ABG analysis, but needs further validation in human patients.

Randomized comparison of the feasibility of three anesthetic techniques for day-case open inguinal hernia repair.

STUDY OBJECTIVE: Comparison of local anesthetic infiltration (LAI), spinal anesthesia (SPIN) and total intravenous anesthesia (TIVA) for open inguinal herniorrhaphy. We hypothesized that patients receiving LAI could be discharged faster than SPIN and TIVA patients. DESIGN: Randomized, prospective trial. SETTING: University hospital day-surgery center. PATIENTS: 156 adult male patients (ASA 1-3) undergoing day-case open inguinal herniorrhaphy. INTERVENTIONS: Patients were randomized to either LAI (lidocaine+ropivacaine), SPIN (bupivacaine+fentanyl) or TIVA (propofol+remifentanil). Perioperative Ringer infusion was 1.5mL/h. Urinary bladder was scanned before and after surgery. Interviews were performed on postoperative days 1, 7 and 90. MEASUREMENTS: Duration of surgery, duration of the patients' stay in the operating room and time until their readiness for discharge home. Patient satisfaction and adverse effects were registered. MAIN RESULTS: Surgery lasted longer in LAI group (median 40min) than in SPIN group (35min) (P=.003) and TIVA group (33min) (P<.001). Although surgery was shortest in TIVA group, TIVA patients stayed longer in the operating room than LAI patients (P=.001). Time until readiness for discharge was shorter in LAI group (93min) than in TIVA (147min) and SPIN (190min) groups (P<.001). Supplementary lidocaine infiltration was given to 32 LAI patients, and IV fentanyl to 29 LAI and 4 SPIN patients. Ephedrine was required in 34 TIVA, 5 LAI and 5 SPIN patients. One SPIN and three LAI patients had to be given TIVA and another SPIN patient LAI to complete the operations. Urinary retention was absent. Discomfort in the scar (26%) three months postoperatively was not anesthesia-related. CONCLUSIONS: Logistically, LAI was superior because of the fastest recovery postoperatively. The anesthetic techniques were adequate for surgery in all but a few LAI and SPIN patients. Lack of urinary retention was probably related to the small IV infusion volumes.

Controlled release ibuprofen-poloxamer gel for epidural use - A pharmacokinetic study using microdialysis in pigs.

In order to avoid the risks of sideeffects of epidural local anesthetics and opioids, the use of nonsteroidal anti-inflammatory drugs (NSAIDs) epidurally would be an interesting option of analgesic therapy. The fairly short duration of action of spinally administered NSAIDs, e.g., ibuprofen, may be prolonged by using controlled release poloxamer gel formulation. Using a microdialysis technique we studied the epidural and intrathecal pharmacokinetics of ibuprofen after its epidural administration as a poloxamer 407 formulation or a solution formulation. In addition, plasma ibuprofen concentrations were analyzed from central venous blood samples. Ibuprofen concentrations in the epidural space were significantly higher and longer lasting after the epidural gel injection compared with the epidural solution injection. The epidural AUC of ibuprofen was over threefold greater after epidural ibuprofen gel injection compared with the ibuprofen solution injection (p<0.001). The systemic absorption of ibuprofen from 25% poloxamer 407 gel was very low. The in situ forming poloxamer gel acted as a reservoir allowing targeted ibuprofen release at the epidural injection site and restricted ibuprofen molecules to a smaller spinal area. Ibuprofen diffusion from the epidural space to the intrathecal space was steady and prolonged. These results demonstrate that the use of epidurally injectable poloxamer gel can increase and prolong ibuprofen delivery from epidural space to the CSF enhancing thus ibuprofen entry into the central neuroaxis for spinal analgesia. Further toxicological and dose-finding studies are justified.

Intravenous lipid emulsion given to volunteers does not affect symptoms of lidocaine brain toxicity.

Intravenous lipid emulsion has been suggested as treatment for local anaesthetic toxicity, but the exact mechanism of action is still uncertain. Controlled studies on the effect of lipid emulsion on toxic doses of local anaesthetics have not been performed in man. In randomized, subject-blinded and two-phase cross-over fashion, eight healthy volunteers were given a 1.5 ml/kg bolus of 20% Intralipid(®) (200 mg/ml) or Ringer's acetate solution intravenously, followed by a rapid injection of lidocaine 1.0 mg/kg. Then, the same solution as in the bolus was infused at a rate of 0.25 ml/kg/min. for 30 min. Electroencephalography (EEG) was recorded, and 5 min. after lidocaine injection, the volunteers were asked to report subjective symptoms. Total and un-entrapped lidocaine plasma concentrations were measured from venous blood samples. EEG band power changes (delta, alpha and beta) after the lidocaine bolus were similar during lipid and during Ringer infusion. There were no differences between infusions in the subjective symptoms of central nervous system toxicity. Lidocaine was only minimally entrapped in the plasma by lipid emulsion, but the mean un-entrapped lidocaine area under concentration-time curve from 0 to 30 min. was clearly smaller during lipid than Ringer infusion (16.4 versus 21.3 mg × min/l, p = 0.044). Intravenous lipid emulsion did not influence subjective toxicity symptoms nor affect the EEG changes caused by lidocaine.

Nitrous oxide analgesia for bone marrow aspiration and biopsy - A randomized, controlled and patient blinded study.

Background and aims Bone marrow aspiration and/or biopsy (BMAB), performed under local anaesthesia in adults, is a common and often painful procedure. Anxiety is known to intensify pain during the procedure. Nitrous oxide (N2O), known for its sedative and analgesic benefit in various short medical procedures and labour pain, could be advantageous also for pain relief during bone marrow examination. N2O acts rapidly and is eliminated in a couple of minutes once the inhalation is stopped, and occasional side effects (e.g. dizziness and nausea) are mild. The aim of this study was to compare the analgesic effects of inhaled 50% mixture of nitrous oxide and oxygen to 50% oxygen during bone marrow examination. Methods In this randomized, controlled, patient and observer blinded study patients received either 50% mixture of nitrous oxide and oxygen or 50% mixture of oxygen in air during bone marrow examination, in addition to local analgesia. Both patient groups comprised 35 adult patients. Pre-procedural anxiety and procedural pain were rated on the Numeral Rating Scale (NRS 0‒10). Cognitive function was measured before and 30 min after the procedure. Possible side effects were recorded. A telephone interview was performed 24 h later. Results There were no statistically significant differences in pain scores of the procedural steps (median NRS ranging 3.0‒4.0) between the study groups. High pain scores of 8‒10 comprised 0% vs. 8.6% of the scores during infiltration, 2.9% vs. 5.7% during puncture, 11.4% vs. 14.3% during aspiration and 2.9% vs. 2.9% during biopsy in N2O and 50% O2 groups, respectively (NS). Pre-procedural anxiety (median NRS 3.5 in both groups), measured in the outpatient clinic just prior to procedure, correlated with pain intensity during bone marrow aspiration (P = 0.045). There were no significant differences between side effects. During the BMAB four patients (3 in N2O group, 1 in 50% O2 group) reported dizziness and one patient in the N2O group reported nausea. Gas inhalation did not affect the cognitive function of the participants. In both groups the majority (>80%) of the patients was satisfied with the inhalation technique. During the 24 h interview, most of the participants were pain free and they did not report any serious adverse effects. Conclusions In spite of similar moderate to strong procedural pain in both groups and no benefit of N2O, most patients were satisfied with the inhalational techniques. We assume that the bedside presence of an anaesthesiologist and the distraction caused by the inhalational arrangements introduced positive context-sensitive therapeutic effect independent of the gas used. Pre-procedural anxiety predicted pain associated with bone marrow aspiration. Implications Inhaled 50% nitrous oxide was not an effective analgesic during bone marrow examination in our unselected outpatient population. Further studies should concentrate on its use with patients predicted to be at increased risk of suffering intense pain during the procedure, such as very anxious patients or those who have a painful history of previous bone marrow examinations.

Intravenous lipid emulsion entraps amitriptyline into plasma and can lower its brain concentration--an experimental intoxication study in pigs.

Intravenous lipid emulsion has been suggested as treatment for severe intoxications caused by lipophilic drugs, including tricyclic antidepressants. We investigated the effect of lipid infusion on plasma and tissue concentrations of amitriptyline and haemodynamic recovery, when lipid was given after amitriptyline distribution into well-perfused organs. Twenty anaesthetized pigs received amitriptyline intravenously 10 mg/kg for 15 min. Thirty minutes later, in random fashion, 20% Intralipid(®) (Lipid group) or Ringer's acetate (Control group) was infused 1.5 ml/kg for 1 min. followed by 0.25 ml/kg/min. for 29 min. Arterial and venous plasma amitriptyline concentrations and haemodynamics were followed till 75 min. after amitriptyline infusion. Then, frontal brain and heart apex samples were taken for amitriptyline measurements. Arterial plasma total amitriptyline concentrations were higher in the Lipid than in the Control group (p < 0.03) from 20 min. on after the start of the treatment infusions. Lipid emulsion reduced brain amitriptyline concentration by 25% (p = 0.038) and amitriptyline concentration ratios brain/arterial plasma (p = 0.016) and heart/arterial plasma (p = 0.011). There were no differences in ECG parameters and no severe cardiac arrhythmias occurred. Two pigs developed severe hypotension during the lipid infusion and were given adrenaline. In conclusion, lipid infusion, given not earlier than after an initial amitriptyline tissue distribution, was able to entrap amitriptyline back into plasma from brain and possibly from other highly perfused, lipid-rich tissues. In spite of the entrapment, there was no difference in haemodynamics between the groups.

Testing of midwife neonatal resuscitation skills with a simulator manikin in a low-risk delivery unit.

BACKGROUND: Expertise in neonatal resuscitation is essential for personnel involved in the care of newborns. In this observational cohort study the skills of 52 midwives in a simulated scenario were assessed. METHODS: A total of 52 midwives in a low-risk unit and five specialist nurses in a high-risk unit were tested to establish their competence in newborn resuscitation. The 52 midwives were divided into groups 1 (n = 39; no pretest training) and 2 (n = 13; 1 day training prior to study). The video-recorded test scenario was a newborn with asphyxia. Thirty items were graded by a neonatologist and nursing team in real time. Using the Angoff method, a pass score was 18.71 for skills that were graded 0 or 1. RESULTS: The average score of specialist nurses was 26 (range, 23-29). A total of 49% of midwives in group 1 and 92% in group 2 passed the test. The average score was 17.7 (range, 9-25) in group 1 and 21.9 (range, 17-27) in group 2. A total of 27% and 77% of midwives in groups 1 and 2, respectively, carried out ventilation at a frequency as per the algorithm. Mask leakage was higher in group 1 (44%) versus group 2 (23%). Five and three midwives in groups 1 and 2, respectively, overexpanded the lungs. CONCLUSION: Many midwives had imperfect resuscitation skills. A 1 day course improved such skills. The standard scenario is an objective and useful performance marker in assessing and documenting improvements in competence in delivery room resuscitation.

In vitro and in vivo entrapment of bupivacaine by lipid dispersions.

Intravenous lipid emulsion is recommended as treatment for local anesthetic intoxication based on the hypothesis that the lipophilic drug is entrapped by the lipid phase created in plasma. We compared a 15.6 mM 80/20 mol% phosphatidyl choline (PC)/phosphatidyl glycerol (PG)-based liposome dispersion with the commercially available Intralipid® emulsion in a pig model of local anesthetic intoxication. Bupivacaine-lipid interactions were studied by electrokinetic capillary chromatography. Multilamellar vesicles were used in the first in vivo experiment series. This series was interrupted when the liposome dispersion was discovered to cause cardiovascular collapse. The toxicity was decreased by an optimized sonication of the 50% diluted liposome dispersion (7.8 mM). Twenty anesthetized pigs were then infused with either sonicated PC/PG liposome dispersion or Intralipid®, following infusion of a toxic dose of bupivacaine which decreased the mean arterial pressure by 50% from baseline. Bupivacaine concentrations were quantified in blood samples using liquid chromatography/mass spectrometry. No significant difference in the context-sensitive plasma half-life of bupivacaine was detected (p=0.932). After 30 min of lipid infusion, the bupivacaine concentration was 8.2±1.5 mg/L in the PC/PG group and 7.8±1.8 mg/L in the Intralipid® group, with no difference between groups (p=0.591). No difference in hemodynamic recovery was detected between groups (p > 0.05).

No antidotal effect of intravenous lipid emulsion in experimental amitriptyline intoxication despite significant entrapment of amitriptyline.

Intravenous lipid emulsion has been used in the resuscitative treatment of intoxications caused by local anaesthetics and tricyclic antidepressants with seemingly beneficial results. We studied the effect of intravenous lipid emulsion on the plasma concentration of amitriptyline and haemodynamic recovery in a pig model of amitriptyline intoxication. Twenty pigs were anaesthetized (1% isoflurane in 21% O(2)) and given amitriptyline 15 mg/kg intravenously for 15 min. In random fashion immediately thereafter, either 20% lipid emulsion (ClinOleic(®), Lipid group) or Ringer's acetate (Control group) was infused for 30 min.; first 1.5 ml/kg for 1 min., followed by 0.25 ml/kg/min. for 29 min. The amitriptyline concentration in total and lipid-poor plasma and haemodynamic parameters were measured until 30 min. after the infusions. Lipid infusion prevented the decrease in plasma total amitriptyline concentration, resulting in a 90% higher (p < 0.001) total concentration and significantly (p = 0.014) lower free fraction of plasma amitriptyline in the Lipid group (1.1%) compared with the Control group (3.0%) at 30 min. Haemodynamic recovery from the intoxication as measured by heart rate, arterial pressure or cardiac output was similar in both groups. However, five pigs in the Lipid group and two pigs in the Control group died. In conclusion, a marked entrapment of amitriptyline by intravenous lipid emulsion was observed but this did not improve the pigs' haemodynamic recovery from severe amitriptyline intoxication. Care should be exercised in the antidotal use of lipid emulsion until controlled human studies indicate its efficacy and safety.

Intravenous lipid emulsion only minimally influences bupivacaine and mepivacaine distribution in plasma and does not enhance recovery from intoxication in pigs.

BACKGROUND: The reported successful use of IV lipid emulsions in local anesthetic intoxications is thought to be due to lipid sequestration of local anesthetics. However, controlled efficacy studies were lacking, and other mechanisms of action have also been suggested. We investigated the effect of lipid infusion on plasma concentrations and cardiovascular effects of 2 local anesthetics differing in lipophilicity, bupivacaine, and mepivacaine. METHODS: Bupivacaine (n = 20) or mepivacaine (n = 20) was infused into a central vein of anesthetized (isoflurane 1%, Fio(2) 0.21) pigs until mean arterial blood pressure decreased to 50% from baseline. Isoflurane was discontinued and Fio(2) was increased to 1.0. Ten pigs in each local anesthetic group were treated with 20% lipid emulsion (ClinOleic®), and 10 pigs with Ringer's solution: 1.5 mL/kg in 1 minute followed by an infusion of 0.25 mL · kg(-1) · min(-1) for 29 minutes. Five additional pigs were infused bupivacaine and Intralipid®. Total and nonlipid-bound local anesthetic concentrations were determined from repeated blood samples. RESULTS: There were no overall differences in total or nonlipid-bound plasma local anesthetic concentrations between the lipid and Ringer's groups. However, plasma median total bupivacaine concentration was 21% and 23% higher at 20 and 30 minutes, respectively, in the lipid group (P = 0.016 without Holm-Bonferroni correction). There was also no overall difference between lipid and Ringer's groups in the rate of recovery of hemodynamic and electrocardiographic variables. Median mean arterial blood pressure in the lipid group with bupivacaine intoxication was 16 mm Hg and 15 mm Hg higher than in the corresponding Ringer's group at 10 and 15 minutes, respectively (P = 0.016 and P = 0.021, respectively, without Holm-Bonferroni correction). Intralipid® also caused no difference between total plasma and nonlipid-bound concentrations of bupivacaine with no apparent enhancement of recovery. CONCLUSIONS: Lipid emulsion neither had any measurable effect on the disposition of the studied local anesthetics in plasma, nor did it improve the rate of recovery from intoxication by either local anesthetic as measured by hemodynamic variables.

Randomised comparison of hyperbaric articaine and hyperbaric low-dose bupivacaine along with fentanyl in spinal anaesthesia for day-case inguinal herniorrhaphy.

BACKGROUND AND OBJECTIVE: Low-dose mixture of hyperbaric bupivacaine and fentanyl is commonly used in day-case spinal anaesthesia. Using hyperbaric articaine, the onset may be faster and duration more predictable than with bupivacaine-fentanyl. We compared these two spinal anaesthetics for inguinal herniorrhaphy. METHODS: Adult patients were randomised to spinal anaesthesia with hyperbaric articaine 84 mg (group A, n = 40) or hyperbaric bupivacaine 7 mg along with fentanyl 10 µg (group B+F, n = 40). A blinded observer tested the block characteristics. Aiming at sensory block spread to T10 dermatome, the operating table was tilted head-end up or down 10° (once or twice), as required. Postoperative telephone interviews were performed. RESULTS: All patients in group A had a sensory block to T10 in a median time of 4 (range 2-20) min. In group B+F, the median onset time of T10 analgesia was 10 (2-30) min (P < 0.001), but T10 analgesia was not reached in seven of 40 B+F patients. A head-up tilt was needed in 37 of 40 group A patients to prevent from too extensive cephalad spread of block, and 34 of 40 group B+F patients needed a head-down tilt to enhance cephalad spread of analgesia. To treat hypotension, 6.4 mg of ephedrine was required, on average, in group A and 1.8 = mg in group B+F (P = 0.01). Median time to recovery from sensory block was significantly shorter in group A (2.5 h) than in group B+F (3 h; P = 0.002). General anaesthesia was needed in three patients (group A, two patients: sensory block too short; group B+F, one patient: sensory block too limited). CONCLUSION: Hyperbaric articaine leads to faster onset of block and faster recovery than bupivacaine along with fentanyl. Hypotension is more common with articaine. The onset and extension of the spinal block are unpredictable when using these techniques.

Revival of old local anesthetics for spinal anesthesia in ambulatory surgery.

PURPOSE OF REVIEW: In recent years, several older (first intrathecal use in the 1950s, 1960s, and 1970s) local anesthetics have been investigated as spinal anesthetics in ambulatory surgery because these drugs are claimed to cause less transient neurologic symptoms (TNS) than lidocaine which was the main spinal anesthetic for surgery of short-duration for decades. The review covers the current literature. RECENT FINDINGS: Several recent reports have dealt with the short-acting chloroprocaine and articaine and the intermediate-duration-acting prilocaine. Mepivacaine, another intermediate-acting drug, was applied in one trial only. Various dosages of these drugs either alone or with a small dose of fentanyl were compared with each other, with lidocaine, or with the currently most commonly used low-dose bupivacaine technique. The recovery from both motor and sensory block was usually reasonably fast. However, occasionally recovery after mepivacaine and prilocaine was prolonged which fits ill in a fast-flow ambulatory setting. TNS cases were very rarely reported. SUMMARY: The newest results corroborate (at least for chloroprocaine, articaine, and prilocaine) previous data that these drugs provide reliable and mostly well tolerated spinal blocks associated with an apparently smaller risk for postanesthesic TNS as compared with lidocaine. Further studies are warranted regarding broader indications, possible usefulness of adjuvants, and for the exploration of the side-effect profiles in detail. To what extent the observed revival of these older, rather well characterized local anesthetics leads to a wider use of spinal anesthesia in the ambulatory setting remains to be seen. This is also dependent on various organizational and local traditional factors.

Intravenous lipid emulsion sequesters amiodarone in plasma and eliminates its hypotensive action in pigs.

STUDY OBJECTIVE: Our objective is to investigate to what extent amiodarone is sequestered by intravenously administered lipid emulsion in plasma of pigs and whether the lipid emulsion inhibits amiodarone-induced hypotension. METHODS: Twenty anesthetized pigs received randomly 1.5 mL/kg bolus injection of olive/soybean oil-based 20% lipid emulsion (lipid group, n=10) or Ringer's acetate solution (control group, n=10) in 1 minute, followed by a continuous infusion of either solution for 30 minutes at 0.25 mL/kg per minute. Simultaneously with these continuous infusions, amiodarone hydrochloride was infused for 20 minutes at 1 mg/kg per minute in both groups. Plasma amiodarone concentration and mean arterial blood pressure were evaluated at predetermined intervals. RESULTS: Plasma amiodarone concentration in the lipid group increased more steeply during the amiodarone infusion than in the control group, at 20 minutes being a median 96.8 mg/L (interquartile range [IQR] 85.4, 102.0 mg/L) in the lipid group and median 21.5 mg/L (IQR 18.9, 22.3 mg/L) in the control group (difference 75.3 mg/L; 95% confidence interval [CI] 65.3 to 85.3 mg/L). After the separation of lipids from plasma by differential centrifugation, less amiodarone was contained in the lipid-poor aqueous fraction. At 20 minutes, the median was 13.3 mg/L (IQR 12.0, 13.7 mg/L), and the difference compared with the total plasma amiodarone concentration was -83.6 mg/L (95% CI -93.3 to -73.8 mg/L). In the lipid group, mean arterial blood pressure was not altered during the continuous amiodarone infusion. In the control group, mean arterial blood pressure decreased from baseline at 11 minutes, and the median was 52 mm Hg (IQR 51, 80 mm Hg) and the difference from baseline was 26 mm Hg (95% CI 9 to 43 mm Hg). Mean arterial blood pressure at 21 minutes also remained below the baseline, and the median was 57 mm Hg (IQR 50, 68 mm Hg) and the difference from baseline was 21 mm Hg (95% CI 9 to 33 mm Hg). CONCLUSION: Amiodarone was sequestered to a great extent by the intravenously administered lipids in plasma, which completely prevented the decrease in arterial blood pressure caused by amiodarone infusion. Further studies are needed to evaluate the clinical usefulness of intravenous lipid emulsion as an antidote in amiodarone overdoses.

The effect of levosimendan on bupivacaine-induced severe myocardial depression in anesthetized pigs.

BACKGROUND AND OBJECTIVES: Levosimendan, an inodilator without proarrhythmogenic properties, has been shown to reverse ropivacaine-induced negative inotropy in isolated heart preparations. In this randomized and blinded study, we investigated whether levosimendan is able to reverse rapidly bupivacaine-induced myocardial depression in pigs. METHODS: Twenty invasively monitored pigs anesthetized with isoflurane 1% received bupivacaine 2 mg/kg per minute into a central vein until mean arterial pressure decreased to 55% of baseline. Thereafter, levosimendan 80 microg/kg for 10 mins, followed by 0.7 microg/kg per minute during the next 50 mins (L-SIM) or corresponding amounts of placebo were administered intravenously. Simultaneously, Ringer's acetate was infused intravenously, 20 mL/kg for 10 mins, followed by 20 mL/kg for 50 mins. RESULTS: Two pigs in each group developed cardiac arrest immediately after bupivacaine and could not be resuscitated. Bupivacaine induced widening of the QRS complex in the electrocardiogram and bradycardia.In the remaining 16 pigs, 3 (2 in L-SIM group and 1 in placebo group) needed short-lasting manual cardiac compression and 1 dose of epinephrine. Cardiac output, ejection fraction, and stroke power/end-diastolic volume recovered initially very rapidly in the L-SIM group.However, there was no time x group effect difference in the overall recovery in the various parameters between the 2 groups, except in heart rate which was higher (P G 0.05) when levosimendan was administered.During the 50-min levosimendan infusion, mean arterial pressure and systemic vascular resistance stayed slightly lower in comparison with placebo infusion, but the difference was not statistically significant. CONCLUSIONS: Levosimendan together with the infusion of Ringer's solution rapidly reversed the cardiac depression, but there was no difference in overall cardiovascular recovery in comparison to treatment with Ringer's solution alone. Levosimendan-induced increase in heart rate possibly facilitated the recovery from bupivacaine intoxication.

Comparison of articaine and lidocaine for infiltration anaesthesia in patients undergoing bone marrow aspiration and biopsy.

Infiltration anaesthesia with articaine, a local anaesthetic able to penetrate bone, may relieve procedural pain better than lidocaine in bone marrow aspiration and biopsy. This randomised, double-blind study comprised 150 patients with suspected or known haematologic disease. Either articaine 20mg/ml (50 patients), articaine 40mg/ml (49 patients) or lidocaine 20mg/ml (51 patients), all with adrenaline 5mug/ml, was infiltrated in volume of 6ml (sternal manubrium), 8ml (sternal body) or 10ml (iliac crest) 2min before puncture. Numeral rating scale score (median, range) at injection of local anaesthetic was 3.0 (0-10), at bone puncture 2.0 (0-8), at aspiration 3.5 (0-10) and at biopsy (48 patients) 3.0 (0-10). Pre-procedural anxiety, rated on a verbal scale, correlated significantly with experienced pain (P<0.01). Very anxious patients had fewer previous bone marrow examinations (P<0.01) and they experienced more pain during aspiration (P<0.05). In the post-interview 42 patients reported appearance of pain (median 2.0, range 1-7) after 6.2h, on average, and 15 patients needed oral analgesics. No parameter differed significantly between the groups. In conclusion, the quality of infiltration anaesthesia for bone marrow punctures and aspiration with articaine and lidocaine was similarly poor. Several patients experienced strong pain which correlated with the degree of anxiety.

Teaching anaesthesia induction to medical students: comparison between full-scale simulation and supervised teaching in the operating theatre.

BACKGROUND AND OBJECTIVE: The aim of the study was to compare the effectiveness of teaching of general anaesthesia induction to medical students using either full-scale simulation or traditional supervised teaching with patients in the operating theatre. METHODS: Forty-six fourth year students attending their course in anaesthesiology were enrolled. The students were randomly assigned to two groups. The simulation group received training in the simulator. The traditional training group was supervised by a senior consultant anaesthetist. After the training sessions all students were tested in the simulator setting. The test was assessed using a 40-item evaluation list. RESULTS: Thirty-three per cent of students in the traditional group and 87% of the students in the simulation group passed the test. Statistically significant differences were: request of glycopyrrolate (P < 0.001), Sp(O2) monitoring (P < 0.001), used gloves when placing an intravenous cannula (P = 0.012), intubation attempt within 30 s (P < 0.04), anaesthesia gas set at MAC at least 1 (P < 0.04), instructed anaesthetic nurse to keep Sp(O2) at least 95% (P < 0.05), keep MAP at least 60 mmHg (P < 0.05), keep heart rate more than 50 beats per minute (P < 0.002), keep end-tidal p(CO2) 4-5.5 kPa (P < 0.002). CONCLUSION: The simulation group performed better in 25% of the tasks and similarly in the others compared with the traditional teaching group. With the same time and amount of teaching personnel we trained five or six students in the simulator compared with one student in the operating theatre. Further research will reveal whether these promising results with simulation may be applied more generally in anaesthesiology teaching to medical students.

An evaluation of the epidural catheter position by epidural nerve stimulation in conjunction with continuous epidural analgesia in adult surgical patients.

BACKGROUND: The epidural stimulation test to confirm epidural catheter position has been described as being simple, fast, and reliable. We evaluated the feasibility of the epidural stimulation test and its potential in contributing to effective postoperative continuous epidural analgesia. METHODS: Thirty adult patients (ASA I-III) undergoing major abdominal surgery or thoracotomy were to receive continuous epidural analgesia at a thoracic level postoperatively. The epidural stimulation test was performed after catheter placement, after local anesthetic boluses, and during epidural analgesia, up to six times in each patient. Catheter positions were verified by epidurography (before start of epidural analgesia and again on the second postoperative day). RESULTS: Several technical issues (e.g., need to flush catheter with saline in order to maintain adequate stimulation during >25% of all measurements) and interpretation problems (e.g., interference of respiratory activity [n = 6]) made the implementation of the epidural stimulation test rather time consuming, both at the time of catheter placement and during epidural analgesia. Immediately after catheter placement (before test dose) the epidural stimulation test did not identify four of four catheters positioned outside the spinal canal. In addition, the initial epidural stimulation test indicated a possible intrathecal or paravertebral placement in 3 of 25 catheters correctly positioned in the epidural space. During 107 of 122 (88%) measurements with the catheter tip situated epidurally and with preceding or simultaneous administration of epidural local anesthetic, the epidural stimulation test elicited a motor response. Continuous epidural analgesia provided adequate pain relief in all 25 patients having positive epidurography. CONCLUSIONS: The epidural stimulation test was often associated with technical difficulties and interpretation problems. The role of the repeated use of the epidural stimulation test for quality assurance in patients undergoing postoperative continuous epidural analgesia remains undetermined.