Intrathecal anesthesia: ropivacaine versus bupivacaine.

We compared intrathecal ropivacaine to bupivacaine in patients scheduled for transurethral resection of bladder or prostate. Doses of ropivacaine and bupivacaine were chosen according to a 3:2 ratio found to be equipotent in orthopedic surgery. One hundred patients were randomly assigned to blindly receive either 10 mg of isobaric bupivacaine (0.2%, n = 50) or 15 mg of isobaric ropivacaine (0.3%, n = 50) over 30 s through a 27-gauge Quincke needle at the L2-3 level in the sitting position. Onset and offset times for sensory and motor blockades and mean arterial blood pressure were recorded. Pain at surgical site requiring supplemental analgesics was recorded. Cephalad spread of sensory blocks was higher with bupivacaine (median level, cold T(4) and pinprick T(7)) than with ropivacaine (cold T(6) and pinprick T(9)) (P<0.001). Eight patients in Group Ropivacaine received IV alfentanil (P<0.01). Onset time (mean +/- SD) to T(10) anesthesia and offset time at L2 were not different (bupivacaine = 13 +/-8 min, 127+/-41 min; ropivacaine = 11+/-7 min, 105+/-29 min). Complete motor blockade occurred in 43 patients with bupivacaine and in 41 patients with ropivacaine (not significant). Total duration of motor blockade was not different. No difference in hemodynamic effects was detected between groups. No patient reported back pain. We conclude that 15 mg of intrathecal ropivacaine provided similar motor and hemodynamic effects but less potent anesthesia than 10 mg of bupivacaine for endoscopic urological surgery.

A novel supraclavicular approach to brachial plexus block.

We describe a novel supraclavicular approach to the brachial plexus. Designated as the intersternocleidomastoid technique, this new approach was tested in unembalmed cadavers. It was then applied for evaluation to 150 ASA grade I or II patients scheduled for elective surgery or physiotherapy of the upper limb or for treatment of reflex sympathetic dystrophy associated with painful shoulder. The new approach was easy to master because of a very simple surface landmark, i.e., the triangle formed by the sternocleidomastoid heads, which were visible and palpable in most patients studied (90%). The procedure was effective intraoperatively, providing satisfactory anesthesia in 140 patients (93%), partially satisfactory blocks in 6 (4%), and unsatisfactory blocks in only 4 (3%). The catheter entry point is cephalad enough not to obscure the surgical field on the shoulder. Catheter insertion was successful in 63 of 70 patients. Postoperative analgesia was provided for 48 h or more in 45 patients and for 24 h in 18 patients. Only minor complications were observed: asymptomatic phrenic nerve block in 89 patients (60%), transient Horner's syndrome in 15 (10%), transient recurrent laryngeal nerve blockade in 2, and misplacement of the catheter into the subclavian vein in 1 patient. No pneumothorax was observed.

Mathematical considerations in the practice of acute normovolemic hemodilution.

BACKGROUND: Acute normovolemic hemodilution (ANH) is recommended as a simple and cost-effective method of autologous transfusion. The present mathematical model, based on the current clinical practice of removing 2 to 3 units of fresh whole blood, defines the indications for ANH. STUDY DESIGN AND METHODS: A mathematical model and subsequent nomograms were developed to define patients for whom removal of 2 to 3 units (450 mL each) would allow a theoretical red cell savings equivalent to 1 unit of packed red cells (volume, 250 mL; hematocrit, 60%), that is, a successful application of the technique. Minimal safe target hematocrits were defined as 30, 26, and 22 percent. RESULTS: The minimal initial hematocrits required for given patient weights are displayed on nomograms derived from the mathematical model. The nomograms also indicate the surgical blood loss allowed without ANH: for example, a 75-kg man, (2-unit ANH, minimal safe hematocrit 22%) requires a minimal initial hematocrit of 42 percent (surgical blood loss of 0.64 x estimated blood volume = 3100 mL). CONCLUSION: ANH involving the removal of 2 to 3 units (450 mL each) may be useful in patients with anticipated blood loss exceeding 50 percent of estimated blood volume, high initial hematocrit, and a capacity to tolerate dilution-induced anemia.

[Etomidate versus propofol for anesthesia in ambulatory cardioversion]. / Etomidat versus Propofol zur Anästhesie bei ambulanter Kardioversion.

OBJECTIVE: This study compared the two short-acting intravenous anaesthetic agents, etomidate in lipid emulsion and propofol, for anaesthesia during elective outpatient cardioversion. METHODS: After institutional approval and informed consent, 40 patients (ASA II/III) scheduled for cardioversion were studied. Patients with a left ventricular ejection fraction < 30% were excluded. The anti-arrhythmic medication was not discontinued, and no patient was given pharmacological premedication. Anaesthesia was induced either with etomidate (in lipid emulsion) 0.25 mg/kg or propofol 1.5 mg/kg. Both agents were administered over 30 seconds. Subsequent increments were given until the patients no longer followed verbal commands and the lid reflex was absent. Patients were allowed to breathe 40% oxygen via face mask. Artificial ventilation was performed if a patient became apnoeic for more than 20 seconds. The blood pressure was monitored continuously with the Finapres noninvasive blood pressure monitor, and the heart rate was recorded simultaneously. All data were collected electronically. The duration of anaesthesia was taken as the period from the start of induction until the opening of the eyes on command. For assessment of recovery from anaesthesia, patients were asked to perform a series of psychomotor tests. RESULTS: The two groups were similar in their demographic and haemodynamic baseline data. In both groups, a significant decrease in blood pressure occurred 120 seconds after anaesthesia induction, which was due to the performance of the cardioversion. Five minutes after induction, the blood pressure returned to baseline in the etomidate group, while it remained below baseline in the propofol group. Propofol caused a significant decrease in heart rate. Significantly more patients needed artificial ventilation after propofol administration because of apnoea. Involuntary muscle movements occurred only in patients receiving etomidate. The immediate emergence from anaesthesia was faster after propofol. However, 15 minutes after awakening there was no difference in psychomotor skills between the two groups. No residual psychomotor impairment was evident 60 minutes after anaesthesia in any patient. All patients were discharged four hours after the cardioversion. CONCLUSIONS: Because the recovery characteristics were similar in both groups, the occurrence of side effects may be a major factor when choosing between etomidate and propofol for outpatient cardioversion.

A new axillary approach for continuous brachial plexus block. A clinical and anatomic study.

Catheter insertion in the neurovascular space by axillary approach allows a continuous brachial plexus block and/or postoperative analgesia. We developed a perivenous technique whereby the approach to the neurovascular sheath is guided under fluoroscopy by a preopacified axillary vein. A randomized study compared this technique to the technique of Selander in ASA grade I-II patients scheduled for surgery or painful physiotherapy of the hand. The study was performed in 36 patients randomly divided into two groups. In Group 1 (n = 18), the catheter was placed according to the technique described by Selander. In Group 2 (n = 18), the catheter was placed using our perivenous technique. A complete block was obtained in all the patients of Group 2 vs only 50% of the patients in Group 1 (P < 0.05). In Group 1 a partial block was observed in 17%, with failure in 33% of the patients. There was no difference in the two groups regarding the time required to perform either technique, the duration of the complete block, the pain score, or the amount of continuously administrated bupivacaine during the first 48 h postoperatively. The plasma concentrations of total bupivacaine (high-performance liquid chromatography) were low in successful blocks, with no differences in the two groups; the median value was 0.68 microgram/mL (95% confidence interval: 0.62-0.89). The concentrations were higher (P < 0.01) in failed blocks; the median value was 1.69 micrograms/mL (95% confidence interval: 0.58-2.8). A complementary anatomic study of three arms from fresh cadavers allowed verification of the correct localization of the Teflon cannula and flexible catheter, as well as homogeneous diffusion of the methylene blue inside the brachial plexus. The perivenous technique for continuous axillary brachial plexus block may improve the success rate due to its radiologic and accurate location of the neurovascular sheath.

Comparison of intravenous and epidural clonidine for postoperative patient-controlled analgesia.

Both epidural and intravenous clonidine are used to provide postoperative analgesia, but in predetermined doses. This double-blind randomized study was designed to 1) determine the clonidine dose inducing pain relief after major orthopedic surgery, when controlled by patient, either intravenously or epidurally; and 2) assess whether these two administration routes are clinically equivalent. At the first complaint of pain after scoliosis correction, patients received an initial dose of 8 micrograms/kg clonidine during 30 min either intravenously (n = 12) or epidurally (n = 12). Then, clonidine was given using a patient-controlled analgesia pump via the corresponding administration route. In both cases, the bolus dose was set at 30 micrograms and the lockout interval at 15 min. Pain (0-100 scale), clonidine requirements, sedation (0-4 scale), and hemodynamics (by fiberoptic pulmonary artery catheter) were measured before and 15, 30, 120, 240, 360, 480, and 600 min after the loading dose was started. Plasma clonidine concentrations and arterial blood gases were determined at the 15th, 30th, 240th, and 480th min. Self-administered and total clonidine doses were larger in the intravenous group than in the epidural group (at 600 min: 372 +/- 110 vs 235 +/- 144 micrograms, and including the initial dose, 814 +/- 114 vs 652 +/- 187 micrograms; mean +/- SD). Clonidine administration resulted in pain relief and sedation in both groups but, for comparable pain relief, sedation scores were lower in the epidural group. No intergroup differences in hemodynamic data were observed, although the decrease in blood pressure occurred earlier in the intravenous group. Plasma clonidine concentrations were higher in the intravenous group than in the epidural group (2.5 +/- 0.6 vs 1.5 +/- 0.5 ng/mL after the initial dose and 2.1 +/- 0.5 vs 1.5 +/- 0.4 ng/mL during self-administration; mean +/- SD). We conclude that analgesia can be achieved postoperatively by both epidural and intravenous clonidine administration. The epidural route is associated with significant reductions in self-administered clonidine dose, and thus in the plasma clonidine concentration, and the level of sedation.(ABSTRACT TRUNCATED AT 250 WORDS)

[Obstetric peridural anesthesia with sufentanil. Is it contraindicated?]. / Geburtschilfliche Peridural-anästhesie mit Sufentanil. Eine Kontraindikation?

The advantages of the addition of low-dose sufentanil to local anaesthetics in epidural analgesia during labour (improvement of analgesia, reduction of total dose of local anaesthetic, reduction of rate of instrumental delivery outweigh) far the disadvantages (pruritus, sedation, potential maternal and neonatal respiratory depression). In over 8000 cases, the addition of incremental sufentanil (7.5 micrograms) up to 30 micrograms has not caused any negative effects on newborns, and hence, the addition of sufentanil is justified; it may even be indicated. Sufentanil has not yet been registered for epidural analgesia in Germany, in contrast to other countries. In considering whether this fact may prohibit its use, two aspects should be discussed: therapy and clinical experiments. The difference lies in the purpose rather than in the method of administration. Ethical and legal requirements for clinical tests are anchored in the declaration of Helsinki and the code of the medical profession. The legal background for therapy is represented in the proviso of the German Civil and Criminal Codes as well as the code of conduct on professional liability of the physician. Pain during labour is no absolute indication for the addition of sufentanil, but there are considerable arguments for its superiority in comparison to other standard procedures: the side effects and complications are very limited. Justification of this method is relatively easy in view of the fact that sufentanil has already been registered for peridural analgesia in obstetrics in many other countries. Last but not least, the patient must give informed consent before any procedure can be performed.

[Hysteroscopy syndrome. Absorption of irrigation fluid in surgical hysteroscopy]. / Das HSK-Syndrom. Einschwemmung der Spülflüssigkeit bei operativen Hysteroskopien.

The availability of adequate endoscopic instruments has led to an increased interest in hysteroscopic surgical procedures. An electrolyte-free irrigation fluid is essential for the distention of the uterine cavity, with acceptable uterine distention occurring at 80-150 mmHg. The HSK syndrome, the intravascular absorption of a hypotonic irrigation fluid with subsequent hypotonic hyperhydration with hyponatremia, has to be considered as a risk during hysteroscopic procedures. Analogous to the TUR syndrome, intravasation occurs through the vascular spaces opened during large ablative surgical procedures resulting in the absorption of the fluid used for irrigation. Occasionally, a tear in the lower uterine segment from dilation or perforation of the uterus may expose large vascular channels. Outflow through the tubes is not a significant factor. Continuous CVP measurement allows the detection of intravascular absorption of the irrigation fluid and may be included in the routine monitoring for these procedures. The duration of the hysteroscopic procedure should be limited to 60 min. Addition of ethanol to the irrigating fluid may be suitable for early detection of fluid absorption. However, commercial solutions are not yet available.

[Which way for the administration of alpha 2-adrenergic agents to obtain the best analgesia?]. / Par quelle voie faut-il administrer les alpha 2-adrénergiques pour obtenir la meilleure analgésie?

Mechanisms of the analgesic actions of alpha 2-adrenergic agonists are likely related to various modulating systems of nociceptive neurotransmission, especially those dependent on opiate receptors. Analgesic action of alpha 2-adrenergic agonists implies alpha 2-adrenergic receptors, strategically located on the dorsal horn neurones of the spinal cord to inhibit the release of substance P in response to peripheral stimuli. However, these receptors are included in the control that supraspinal sites exert via the descending medullospinal noradrenergic pathway. Because of its high lipophilic structure, alpha 2-adrenergic agonist can easily penetrate into the central nervous system, reproducing the effects of activation of medullospinal noradrenergic pathway. Alpha 2-adrenergic agonists have been found to be efficient in human pain treatment after systemic, spinal or troncular administration, but there were few randomized clinical studies comparing analgesia potency and adverse effects of either systemic or regional administrations. Clonidine added to local anaesthetic agents increases the analgesic effects in a greater extent than systemic administration of similar dose, probably because this effect depends on the local clonidine concentration. Extradural administration of clonidine is also more efficient than systemic administration, at least when high doses are injected. This superiority is questionable when low-dose clonidine is used. Adverse effects are quite similar in both systemic and spinal routes. Invasiveness of extradural route may be considered in regard to the gain which may be expected in analgesia efficiency.

Vital organ blood flow during deliberate hypotension in dogs.

Increasing the inspiratory concentration of isoflurane is a commonly used technique for producing deliberate hypotension (DH) when isoflurane is used as the principal anesthetic. When an intravenous anesthetic technique is used, DH can be produced by the administration of a peripheral vasodilator, eventually in association with low concentrations of isoflurane. The aim of this investigation was to compare the effects of these two different approaches on vital organ blood flow. DH was induced in 12 mongrel dogs with two different anesthetic techniques: inhaled anesthesia with isoflurane (ISO) or an intravenous anesthetic technique combining propofol and alfentanil in combination with the alpha-adrenoreceptor antagonist, urapidil, and isoflurane at low end-expiratory concentrations. Mean arterial pressure (MAP) was initially decreased by 20% of its baseline and then to 50 mm Hg. Vital organ blood flows and the cerebral metabolic rate for oxygen were determined at each decrement in MAP, and after discontinuation of DH. A decrease in cardiac output was observed in the ISO group when MAP was decreased to 50 mm Hg. Cerebral blood flow was constantly and significantly higher in the ISO group. The cerebral metabolic rate for oxygen did not change compared to baseline values in both groups. At a MAP of 50 mm Hg, a decrease in renal blood flow was observed in both groups. Splanchnic blood flow remained stable in the intravenous anesthetic group in contrast to the ISO group where splanchnic blood flow decreased significantly.(ABSTRACT TRUNCATED AT 250 WORDS)

[Monitoring patients in the anesthesia recovery room. Continuous transcutaneous O2 and CO2 measurements]. / Uberwachung des Patienten im Aufwachraum. Kontinuierliche transkutane O2- und CO2-Messung.

To establish whether continuous transcutaneous O2 and CO2 measurement in the recovery room is suitable for non-invasive monitoring of spontaneous respiration in patients newly operated upon, comparative transcutaneous and arterial pO2 and pCO2 investigations were carried out on 35 adults. There was a correlation coefficient of 0.66 between paO2 and tcpO2. The transcutaneous pO2 values measured were 45.3 mm Hg under the arterial values. When the transcutaneous CO2 values were compared with the arterial values, the correlation coefficient was 0.906. The mean transcutaneous pCO2 values measured lay around 0.7 mm Hg above the arterial values. On the basis of this slight deviation in CO2 values, the method appears to be suitable for continuous non-invasive determination of pCO2. The very large deviations in the O2 values indicate that transcutaneous measurement of oxygen partial pressure in this specific examination situation is not sufficiently reliable, which makes questionable the practice of using one piece of equipment for both measurements. In the clinical setting presented, transcutaneous O2 monitoring does not represent an alternative to close clinical observation and pulse oximetry.

[CSE--the combination of spinal and epidural anesthesia]. / KSE--die Kombination aus spinaler und epiduraler Anaesthesie.

The availability of very fine-bore, long spinal needles (28/10 Ga) has stimulated a new wave of interest in the technique of combined spinal-epidural anesthesia. The original double-puncture technique has progressed due to special combination needles to the current spinal-needle-through-epidural-needle technique. The availability of adapted Tuohy needles, special combination sets, and long spinal needles indicates a lack of standardization. An appropriate introduction technique via Tuohy needle allows identification of the anatomic landmarks and contributes to successful anesthesia. The spinal component allows a rapid onset and intense analgesia with appropriate muscle relaxation. The epidural catheter allows the administration of agents into the epidural space as well as optimization and prolongation of analgesia in the postoperative phase. Confirming the position of the epidural catheter introduced after spinal anesthesia has been established remains a matter of concern.