Epidural blood patch illustrated by CT-epidurography

Four patients, who received epidural blood patch to treat postdural puncture headache, were examined with computed tomography in order to demonstrate the distribution of the injected blood. Blood alone could not be identified, but adding 2 ml contrast agent Iohexol 180 mg J/ ml (Omnipaque®, Nycomed Imaging) to 18 ml blood gave an excellent demonstration of the distribution of the blood in the epidural space, both cranio-caudally (7–14 segments) and spatially in relation to the epidural septae. The blood-contrast media had a strong affinity to the dural sac. There was no support of the spacefilling effect of blood patch.     

Epidural block for obstetrics: Comparison of bolus injection of local anesthetic with gravity flow technique

Study Objective: To test the hypothesis that slow administration of local anesthetic into the epidural space by gravity flow reduces the incidence of signs and symptoms of unintended injection.

Design: Prospective, randomized study.

Setting: Teaching hospital.

Patients: 600 ASA physical status I and II parturients scheduled for labor and delivery or elective cesarean section.

Interventions: After identification of the epidural space with pulsations of an air-fluid column, parturients for vaginal delivery (n = 380) were randomized to receive a test dose of 3 ml 3% 2-chloroprocaine with epinephrine 20 μg, two doses of 7 ml bupivacaine 0.03 % with sufentanil 1 μg/ml and epinephrine 2 μg/ml by either gravity flow (Group 1) given over 30 seconds or by bolus injection (Group 2) given over 5 seconds through the epidural needle; parturients for Cesarean delivery (n = 220) were randomized to receive a test dose and two doses of 6 ml lidocaine 2 % with sufentanil 1 μg/ml and epinephrine 2 μg/ml by either gravity flow or by bolus injection through the epidural needle. Changes in maternal heart rate (HR) and blood pressure, signs of intravascular injection, and adverse effects of epidural bupivacaine-sufentanil were recorded after each dose.

Measurements and Main Results: Gravity flow administration (Group 1) was associated with a smaller increase in mean maternal HR (p < 0.001), less hypotension (p < 0.01), sedation (p < 0.01), nausea (p = 0.01), and segmental spread (p < 0.0001) than were corresponding doses given by traditional bolus injection (Group 1) for vaginal or Cesarean deliveries. The incidence of systemic toxicity was zero of 300 (0%) with gravity flow and 4 of 300 (1.3%) by bolus injection, p = 0.12, Fisher's exact test. No patient in either group had an accidental intrathecal injection.

Conclusion: Gravity flow administration of local anesthetic-opioid solution during epidural block for obstetrics was associated with fewer signs of systemic drug absorption and cardiovascular perturbations than was the traditional bolus injection. This study supports the current opinion that slow administration of local anesthetic during epidural black contributes to fewer adverse events.     

Cerebral blood flow, cerebral metabolic rate of oxygen and relative CO2 reactivity during neurolept anaesthesia in patients subjected to craniotomy for supratentorial cerebral tumours

In 10 patients subjected to craniotomy for supratentorial cerebral tumours in neurolept anaesthesia, cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) were measured twice peroperatively by a modification of the Kety & Schmidt technique, using 133Xe. The relative CO2 reactivity was assessed indirectly as the % change of the arteriovenous oxygen difference (AVDO2) per mm change in PaCO2. The patients were premedicated with diazepam 10-15 mg perorally. For induction, thiopentone 4-6 mg/kg, droperidol 0.2 mg/kg and fentanyl 5 micrograms/kg were used, and for maintenance N2O 67% and fentanyl 4 micrograms/kg/h. During the first flow measurement the median and range of CBF was 30 ml/100 g/min (range 17-45), of AVDO2 8.0 vol % (range 4.1-9.5), and of CMRO2 2.28 ml O2/100 g/min (range 1.57-2.84). During the second CBF study, AVDO2 increased to 9.3 vol % (range 3.4-11) (P less than 0.05), and CMRO2 increased to 2.51 ml O2/100 g/min (range 1.88-3.00) P less than 0.05, while CBF was unchanged. The CO2 reactivity was present in all studies, median 1.8%/mmHg (range 0.5-15.1). The correlation coefficients between jugular venous oxygen tension/saturation, respectively, and CBF were high at tensions/saturations exceeding 4.0 kPa and 55%, indicating that hyperperfusion is easily unveiled by venous samples from the jugular vein during this anaesthesia.     

紧闭式氧化亚氮麻醉方法的探讨

２５例选择期手术病人采用紧闭式氧化亚氮麻醉方法，术中持续监测呼气末氧和氧化亚氮浓度，脉搏血氧饱和度和呼吸循环指标，术中观察紧闭式麻醉后呼吸末氧化亚氮，氧浓度变化，结果：紧闭式麻醉１，２，３ｈ后氧化亚氮浓度分别为５２．７％，５６％，６４．９％，氧浓度为４２．１％，３４．４％，３０．８％，随麻醉时间的延长，气道压力先降后回升，约３ｈ恢复至紧闭麻醉前的水平，紧闭式麻醉前后在本组观察时间内动脉血气分析提示     

Alfentanil or fentanyl during isoflurane–based anaesthesia for day–care knee arthroscopy?

Forty patients agreed to participate in a study to compare whether fentanyl or alfentanil used as analgesic is associated with quicker recovery following anaesthesia for outpatient arthroscopy procedure. Psychomotor tests including choice reaction time (CRT), perceptive accuracy test (PAT) and finger tapping test (FTT) were done prior to induction of anaesthesia with propofol (2–3 mg–kg^-1). Patients were then divided into two groups: Group F (fentanyl) received 0.1 mg fentanyl prior to start of surgery and thereafter 0.05 mg every 30 min during the procedure. Group A (alfentanil) received 0.5 mg alfentanil prior to the onset of surgery and 0.25 mg every 15 min thereafter. Anaesthesia was then maintained using isoflurane (0.5–2%) in oxygen and air (Fio₂ 0.33) during spontaneous respiration with a face mask in a Bain's system. Psychomotor tests were repeated every 45 min postoperatively. Clinical recovery, visual analogue pain intensity score (VAS) and time to discharge home were also assessed by a nurse blind to the method used. Patients in Group A returned to baseline values on the FTT after 90 min while those in Group F did not return to baseline values until 135 min after the end of the operation. Clinical recovery and time to discharge home ("home ready") were also significantly longer in Group F. There was no difference in recovery as seen in the PAT and CRT between the groups. Also, there was no difference in the incidence of side effects and the pain intensity (VAS) scores were similar in the two groups at all time periods. We conclude that recovery following alfentanil is quicker compared to fentanyl when anaesthesia is based on isoflurane.     

2-chloroprocaine antagonism of epidural morphine analgesia

Background: 2-chloroprocaine (2-CP) used for lumbar epidural anesthesia (LEA) reportedly decreases the efficacy of epidural morphine (EM) administered for post-cesarean section (CS) analgesia. The amount of supplemental i.v. morphine self-administered by the patient via the patient-controlled analgesia device (PCA) is used to study the interaction between EM and 2-CP.
Methods: Forty-two patients scheduled for elective CS were randomly divided into 3 equal groups, and received 2-CP, 2-CP+epinephrine (Epi, 5 μg ml^-1) or 2% lidocaine (Lido) with Epi for LEA. All patients received 5 mg EM and i.v. PCA morphine for postoperative pain. Cumulative amount of i.v. morphine used in the first 24 hours as well as the amount of the drug used during each 2-h period were noted. Nonparametric analysis of variance and Chi-squared analysis were used for statistical comparisons.
Results: The mean cumulative 24-h i.v. PCA morphine requirement in the 2-CP, 2-CP+Epi and Lido+Epi groups respectively was 20.5±24, 33.1.5±27 and 4.07±6.3 (mean±SD). The Lido+Epi group used significantly less morphine ( P = 0.01) compared to either of the 2-CP groups with no significant difference between the 2-CP groups. The maximum i.v. PCA morphine use occurred in the first 4 hours following surgery in all three groups.
Conclusion: Analgesic efficacy of EM is decreased when 2-CP is used for LEA compared to when Lido+Epi is used.     

A Comparative Study of the Percutaneous versus Intraoral Technique for Mental Nerve Block

Objective: Mental nerve block is frequently used to aid repair of facial lacerations; both percutaneous and intraoral approaches to blocking this nerve are used, but have never been compared. The authors compared the two techniques for pain of administration and effectiveness of anesthesia. Methods: A prospective, randomized, single-blind, crossover study was conducted using ten healthy volunteers aged 22 to 33 years. Patients having prior experience with mental nerve blocks, lidocaine allergy, active oral/facial infection, or previous facial fractures were excluded. Bilateral mental nerve blocks were done using intraoral technique on one side and percutaneous technique on the other. Both techniques were used by the same investigator and were carried out with 27-gauge needles and 2.5 mL of 2% buffered lidocaine at room temperature injected over 20 seconds. The oral mucosa was topically anesthetized with viscous lidocaine for 1 minute prior to intraoral injection. The orders of the blocks and sides of the face anesthetized were randomized. Subjective and objective pain (visual-analog scale), efficacy (anesthesia of lower lip), time to onset, and duration of anesthesia were evaluated. Results: The intraoral technique was subjectively less painful than the percutaneous approach in nine of ten subjects (p = 0.02). Scores on the visual-analog pain scale were significantly lower for the intraoral technique (p = 0.03). Intraoral injection produced lower-lip anesthesia in 10/10 subjects versus 7/10 for percutaneous (p = 0.25). Times to onset (approximately 1–2 minutes) and durations of anesthesia (approximately one hour) were similar for the two techniques. Conclusion: The intraoral approach to the mental nerve block with adjunctive topical anesthesia was subjectively and objectively less painful than the percutaneous approach without adjunctive anesthesia. While the intraoral approach had a greater efficacy of lower-lip anesthesia and a longer duration of action, these differences were not statistically significant.     

Clinical experience with minimal flow xenon anesthesia

Xenon is a more potent anesthetic than nitrous oxide, and gives more profound analgesia. This investigation was performed to assess the potential of xenon for becoming an anesthetic inspite of its high manufacturing cost. Seven ASA I—-II patients undergoing cholecystectomy (n = 4), hernia repair (n = 2), or mammoplasty (n=l) were studied. Denitrogenation by 15–20 min of oxygen breathing under propofol anesthesia was followed by fentanyl–supplemented xenon anesthesia administered via an automatic minimal flow system which held the oxygen concentration at 30%. Xenon anesthesia lasted 76–228 min and 8–14 1 of xenon (ATPD) was used, of which 5.6–8.1 1 was expended during the first 15 min. Anesthesia appeared to be satisfactory, and the patients woke up rapidly after xenon was discontinued. The automatic system made minimal flow xenon anesthesia easy to administer, but nitrogen accumulation is still a problem. Assuming a xenon price of 10 US $ per litre, the average cost for xenon was about 65 US $ for the first 15 min and then about 25 USS for each subsequent hour of anesthesia.