Spread of injectate around hip articular sensory branches of the femoral nerve in cadavers.

BACKGROUND: Anatomical knowledge dictates that regional anaesthesia after total hip arthroplasty requires blockade of the hip articular branches of the femoral and obturator nerves. A direct femoral nerve block increases the risk of fall and impedes mobilisation. We propose a selective nerve block of the hip articular branches of the femoral nerve by an ultrasound-guided injection in the plane between the iliopsoas muscle and the iliofemoral ligament (the iliopsoas plane). The aim of this study was to assess whether dye injected in the iliopsoas plane spreads to all hip articular branches of the femoral nerve. METHODS: Fifteen cadaver sides were injected with 5 mL dye in the iliopsoas plane guided by ultrasound. Dissection was performed to verify the spread of injectate around the hip articular branches of the femoral nerve. RESULTS: In 10 dissections (67% [95% confidence interval: 38-88%]), the injectate was contained in the iliopsoas plane staining all hip articular branches of the femoral nerve without spread to motor branches. In four dissections (27% [8-55%]), the injection was unintentionally made within the iliopectineal bursa resulting in secondary spread. In one dissection (7% [0.2-32%]) adhesions partially obstructed the spread of dye. CONCLUSION: An injection of 5 mL in the iliopsoas plane spreads around all hip articular branches of the femoral nerve in 10 of 15 cadaver sides. If these findings translate to living humans, injection of local anaesthetic into the iliopsoas plane could generate a selective sensory nerve block of the articular branches of the femoral nerve without motor blockade.

Sonographic visualization and ultrasound-guided blockade of the greater occipital nerve: a comparison of two selective techniques confirmed by anatomical dissection.

BACKGROUND: Local anaesthetic blocks of the greater occipital nerve (GON) are frequently performed in different types of headache, but no selective approaches exist. Our cadaver study compares the sonographic visibility of the nerve and the accuracy and specificity of ultrasound-guided injections at two different sites. METHODS: After sonographic measurements in 10 embalmed cadavers, 20 ultrasound-guided injections of the GON were performed with 0.1 ml of dye at the classical site (superior nuchal line) followed by 20 at a newly described site more proximal (C2, superficial to the obliquus capitis inferior muscle). The spread of dye and coloration of nerve were evaluated by dissection. RESULTS: The median sonographic diameter of the GON was 4.2 x 1.4 mm at the classical and 4.0 x 1.8 mm at the new site. The nerves were found at a median depth of 8 and 17.5 mm, respectively. In 16 of 20 in the classical approach and 20 of 20 in the new approach, the nerve was successfully coloured with the dye. This corresponds to a block success rate of 80% (95% confidence interval: 58-93%) vs 100% (95% confidence interval: 86-100%), which is statistically significant (McNemar's test, P=0.002). CONCLUSIONS: Our findings confirm that the GON can be visualized using ultrasound both at the level of the superior nuchal line and C2. This newly described approach superficial to the obliquus capitis inferior muscle has a higher success rate and should allow a more precise blockade of the nerve.

Ultrasound-guided blocks of the ilioinguinal and iliohypogastric nerve: accuracy of a selective new technique confirmed by anatomical dissection.

BACKGROUND: Ilioinguinal and iliohypogastric nerve blocks may be used in the diagnosis of chronic groin pain or for analgesia for hernia repair. This study describes a new ultrasound-guided approach to these nerves and determines its accuracy using anatomical dissection control. METHODS: After having tested the new method in a pilot cadaver, 10 additional embalmed cadavers were used to perform 37 ultrasound-guided blocks of the ilioinguinal and iliohypogastric nerve. After injection of 0.1 ml of dye the cadavers were dissected to evaluate needle position and colouring of the nerves. RESULTS: Thirty-three of the thirty-seven needle tips were located at the exact target point, in or directly at the ilioinguinal or iliohypogastric nerve. In all these cases the targeted nerve was coloured entirely. In two of the remaining four cases parts of the nerves were coloured. This corresponds to a simulated block success rate of 95%. In contrast to the standard 'blind' techniques of inguinal nerve blocks we visualized and targeted the nerves 5 cm cranial and posterior to the anterior superior iliac spine. The median diameters of the nerves measured by ultrasound were: ilioinguinal 3.0x1.6 mm, and iliohypogastric 2.9x1.6 mm. The median distance of the ilioinguinal nerve to the iliac bone was 6.0 mm and the distance between the two nerves was 10.4 mm. CONCLUSIONS: The anatomical dissections confirmed that our new ultrasound-guided approach to the ilioinguinal and iliohypogastric nerve is accurate. Ultrasound could become an attractive alternative to the 'blind' standard techniques of ilioinguinal and iliohypogastric nerve block in pain medicine and anaesthetic practice.

Ultrasound guidance in regional anaesthesia.

The technology and clinical understanding of anatomical sonography has evolved greatly over the past decade. In the Department of Anaesthesia and Intensive Care Medicine at the Medical University of Vienna, ultrasonography has become a routine technique for regional anaesthetic nerve block. Recent studies have shown that direct visualization of the distribution of local anaesthetics with high-frequency probes can improve the quality and avoid the complications of upper/lower extremity nerve blocks and neuroaxial techniques. Ultrasound guidance enables the anaesthetist to secure an accurate needle position and to monitor the distribution of the local anaesthetic in real time. The advantages over conventional guidance techniques, such as nerve stimulation and loss-of-resistance procedures, are significant. This review introduces the reader to the theory and practice of ultrasound-guided anaesthetic techniques in adults and children. Considering their enormous potential, these techniques should have a role in the future training of anaesthetists.

Ultrasound guidance for infraclavicular brachial plexus anaesthesia in children.

Ultrasonography may offer significant advantages in regional anaesthesia of the upper and lower limbs. It is not known if the same advantages demonstrated in adults also apply to children. We therefore performed a prospective, randomised study comparing ultrasound visualisation to conventional nerve stimulation for infraclavicular brachial plexus anasesthesia in children. Forty children scheduled for arm and forearm surgery underwent infraclavicular brachial plexus blocks with ropivacaine 0.5 ml.kg(-1) guided by either nerve stimulation or ultrasound visualisation. Evaluated parameters included sensory block quality, sensory block distribution and motor block. All surgical procedures were performed under brachial plexus anaesthesia alone. Direct ultrasound visualisation was successful in all cases and was associated with significant improvements when compared with the use of nerve stimulation: lower visual analogue scores during puncture (p = 0.03), shorter mean (median) sensory onset times (9 (5-15) min vs. 15 (5-25) min, p < 0.001), longer sensory block durations (384 (280-480) min vs. 310 (210-420) min, p < 0.001), and better sensory and motor block scores 10 min after block insertion. Ultrasound visualisation offers faster sensory and motor responses and a longer duration of sensory blockade than nerve stimulation in children undergoing infraclavicular brachial plexus blocks. In addition, the pain associated with nerve stimulation due to muscle contractions at the time of insertion is eliminated.

Recollection of dreams after short general anaesthesia: influence on patient anxiety and satisfaction.

BACKGROUND AND OBJECTIVE: We ascertained whether dreams during short general anaesthesia influence subsequent patient satisfaction and anxiety. METHODS: Fifty female patients were randomized into two groups to test for a difference between intravenous and inhalational anaesthesias. In Group Propo, anaesthesia was induced and maintained with propofol; in Group Metho-Iso, anaesthesia was induced with methohexital and maintained with isoflurane. Satisfaction and anxiety with anaesthesia were evaluated using a visual analogue scale from 0 to 100. Dream incidence rate, satisfaction and anxiety were assessed from immediately after waking until 3 months later. RESULTS: Seventeen patients (34%) dreamed during anaesthesia. There were no significant differences in satisfaction or anxiety after anaesthesia between the dreaming and non-dreaming patients (satisfaction, 92.3 +/- 21.6 versus 92.1 +/- 21.6; anxiety, 21.1 +/- 21.1 versus 30.3 +/- 32.1), or between Group Propo and Group Metho-Iso (satisfaction, 94.4 +/- 19.3 versus 90.0 +/- 23.4; anxiety, 26.0 +/- 27.6 versus 28.4 +/- 30.7). There was no significant difference in the incidence rate of dreaming with the type of anaesthesia used (Group Propo, 11 patients; Group Metho-Iso, 6 patients). CONCLUSIONS: Dreaming during general anaesthesia is common but does not influence satisfaction or anxiety after anaesthesia.

Brachial plexus anaesthesia in children: lateral infraclavicular vs axillary approach.

BACKGROUND: Brachial plexus blockade is a well-established technique in upper-limb surgery. In paediatric patients, the axillary route is usually preferred to infraclavicular approaches because of safety considerations. Recent reports on a lateral infraclavicular approach offering greater safety in adults prompted us to perform a prospective randomized study to assess the analgesic efficacy of axillary vs lateral vertical infraclavicular brachial plexus (LVIBP) blocks in paediatric trauma surgery. METHODS: Forty paediatric trauma patients (ASA physical status I and II, age range 1-10 years) scheduled for forearm or hand surgery were randomly assigned to either axillary brachial plexus (ABP group) or LVIBP group blocks using 0.5 ml.kg(-1) ropivacaine 0.5%. Sensory blockade was evaluated by a visual analogue score and Vester-Andersen's criteria, the distribution of sensory and motor blockade was evaluated by a simplified pinprick test and motor tests. RESULTS: In the LVIBP group, Vester-Andersen's criteria were met by 100% of children, compared with 80% in the ABP group (P=0.035). Based on all assessable children, sensory blockade in the primary sensory regions of various nerves was significantly more effective in the LVIBP group (axillary: P < 0.0001; musculocutaneous: P=0.002; medial brachial cutaneous; P=0.008). Motor blockade was also significantly more effective (axillary: P < 0.0001; musculocutaneous: P=0.003). No major complications were observed in either group. DISCUSSION: We conclude that LVIBP blocks can be safely performed in children and that they add to the spectrum of sensory and motor blockade seen with the axillary approach.

A comparison of propofol and sevoflurane anaesthesia: effects on aortic blood flow velocity and middle cerebral artery blood flow velocity.

We compared systemic (aortic) blood flow and cerebral blood flow velocity in 30 patients randomly allocated to receive either propofol or sevoflurane anaesthesia. Cerebral blood flow velocity (CBFv) was measured in the middle cerebral artery using transcranial Doppler. Systemic blood flow velocity (SBFv) was measured in the aorta using transthoracic Doppler sonography at the level of the aortic valve. Bispectral index (BIS) was used to measure the depth of anaesthesia. Measurements were made in the awake patient and repeated during propofol or sevoflurane anaesthesia, with BIS measurements of 40-50. The effects of SBFv on CBFv were estimated by calculating the cerebral/systemic blood flow velocity-index (CsvI). A CsvI value of 100 indicating a 1 : 1 relationship between CBFv and SBFv. The results demonstrated that propofol anaesthesia produced a significantly greater reduction in CsvI than did sevoflurane anaesthesia [propofol: 60 (19); sevoflurane: 83 (16), p = 0.009, t-test]. This suggests a direct reduction in CBFv independent of SBFv during propofol anaesthesia. The greater reduction of CBFv occurring during propofol anaesthesia may be due to lower cerebral metabolic demand compared with sevoflurane anaesthesia at comparable depths of anaesthesia.

Ultrasonographic assessment of topographic anatomy in volunteers suggests a modification of the infraclavicular vertical brachial plexus block.

BACKGROUND: The infraclavicular vertical brachial plexus block, first described by Kilka and coworkers, offers a more proximal spread of anaesthesia for the upper extremity than the classic axillary approach. In this technique, the puncture site is defined as lying at the exact centre of an infraclavicular line (k) between the jugular fossa and the ventral process of the acromion. Our study was designed to determine whether the point so defined (P) corresponds with the optimal puncture site determined sonographically (S) and to develop an improved prediction model. METHOD: High-resolution ultrasonography was carried out in 59 volunteers to visualize the plexus. Sonography-derived distances and morphometric measurements were used to test accuracy and calculate multiple regressions. RESULTS: We found a clear trend towards a more lateral puncture site. In women, S was significantly (P<0.001) lateral (8 mm) to P. The overall accuracy of the infraclavicular vertical brachial plexus block technique was not sufficient to predict the optimal puncture site reliably. Our resulting improved prediction model is valid for both sexes and is based not just on the centre point but on the absolute length of k (22-22.5 cm). We found that for every 1 cm decrease in k the optimal puncture site moved 2 mm laterally from the exact centre of k, and for every 1 cm increase in k it moved 2 mm medially. CONCLUSIONS: The suggested modification should help to increase the success rate of the infraclavicular vertical brachial plexus block while decreasing the rate of potentially severe complications, although individual ultrasonographic guidance is to be recommended whenever possible.

Serum cholinesterase activity reflects morbidity in burned patients.

Blood samples of 200 patients with thermal injuries were drawn apparently to determine the trend of the cholinesterase activity. In relation to the severity of the injury, a characteristic decrease was noted during the first days after admission. A recovery to normal values was achieved in all survivors (150 patients) after a proportionate period of time, but in the group of non-survivors (50 patients), no complete recovery to normal levels was found. Furthermore, a significant relationship between serum cholinesterase activity and the severity of morbidity was detected, the fall of the cholinesterase activity at the very beginning was significantly higher (P<0.004) in patients who died (1.3kU/l) than in patients who survived (0.7kU/l). Already 24h after admission, the mean activity was significantly lower (P<0.003) in non-survivors (2.5kU/l) than in survivors (3.2kU/l). It seems that the serum cholinesterase is a sensitive indicator for the morbidity of patients with severe burn injuries.

Influence of aortic blood flow velocity on changes of middle cerebral artery blood flow velocity during isoflurane and sevoflurane anaesthesia.

BACKGROUND AND OBJECTIVE: We studied the influence of systemic (aortic) blood flow velocity on changes of cerebral blood flow velocity under isoflurane or sevoflurane anaesthesia. METHODS: Forty patients (age: isoflurane 24-62 years; sevoflurane 24-61 years; ASA I-III) requiring general anaesthesia undergoing routine spinal surgery were randomly assigned to either group. Cerebral blood flow velocity was measured in the middle cerebral artery by transcranial Doppler sonography (depth: 50-60 mm). Systemic blood flow velocity was determined by transthoracic Doppler sonography at the aortic valve. Heart rate, arterial pressure, arterial oxygen saturation and body temperature were monitored. After standardized anaesthesia induction (propofol, remifentanil, vecuronium) sevoflurane or isoflurane were used as single agent anaesthetics. Cerebral blood flow velocity and systemic blood flow velocity were measured in the awake patient (baseline) and repeated 5 min after reaching a steady state of inspiratory and end-expiratory concentrations of 0.75, 1.00, and 1.25 mean alveolar concentrations of either anaesthetic. To calculate the influence of systemic blood flow velocity on cerebral blood flow velocity, we defined the cerebral-systemic blood flow velocity index (CSvI). CSvI of 100% indicates a 1:1 relationship of changes of cerebral blood flow velocity and systemic blood flow velocity. RESULTS: Isoflurane and sevoflurane reduced both cerebral blood flow velocity and systemic blood flow velocity. The CSvI decreased significantly at all three concentrations vs. 100% (isoflurane/sevoflurane: 0.75 MAC: 85 +/- 25%/81 +/- 23%, 1.0 MAC: 79 +/- 19%/74 +/- 16%, 1.25 MAC: 71 +/- 16%/79 +/- 21%; [mean +/- SD] P = 0.0001). CONCLUSIONS: The reduction of the CSvI vs. 100% indicates a direct reduction of cerebral blood flow velocity caused by isoflurane/sevoflurane, independently of systemic blood flow velocity.

Ultrasonographic findings of the axillary part of the brachial plexus.

UNLABELLED: In this prospective study we sought to determine anatomic variations of the main brachial plexus nerves in the axilla and upper arm via high-resolution ultrasonography (US) examination. Positions of nerves were studied via US in three sectional levels of the upper arm in 69 healthy volunteers (31 men and 38 women, median age 28 yr). Analysis was done by subdividing the US picture into eight pie-chart sectors and matching sectors for the position of the ulnar, radial, and median nerves. Shortly after the nerves pass the pectoralis minor muscle, they begin to diverge. At the middle level 9%-13%, and at the distal level, 30%-81% of the nerves are not seen together with the artery in the US picture. At the usual level of axillary block approach, we found the ulnar nerve in the posterior medial position in 59% of the volunteers. The other two nerves had two peaks in distribution: the radial nerve in posterior lateral (38%) and anterior lateral (20%) position, and the median nerve in anterior medial (30%) and posterior medial (26%) position. Applying light pressure distally can displace nerves to the side, especially when they are positioned anterior to the axillary artery. We conclude that an axillary block should be attempted as proximal as possible to the axilla. IMPLICATIONS: This prospective ultrasonography study demonstrates significant anatomic variations of the main brachial plexus nerves in the axilla and upper arm, which may increase the difficulty in identifying neural structures. Applying light pressure on the plexus can move nerves to the side, especially when they are positioned anterior to the axillary artery.

S(+)-ketamine for rectal premedication in children.

Our purpose for this prospective, randomized, and double-blinded study was to evaluate the anesthetic efficacy of S(+)-ketamine, an enantiomer of racemic ketamine, compared with a combination of S(+)-ketamine and midazolam, and plain midazolam for rectal premedication in pediatric anesthesia. Sixty-two children, ASA physical status I and II, scheduled for minor surgery, were randomly assigned to be given rectally one of the following: 1.5 mg/kg preservative-free S(+)-ketamine, a combination of 0.75 mg/kg preservative-free S(+)-ketamine and 0.75 mg/kg midazolam, or 0.75 mg/kg midazolam. Preoperative anesthetic efficacy was graded during a period of 20 min by using a five-point scale from 1 = awake to 5 = asleep. Tolerance during anesthesia induction via face mask was graded by using a four-point scale from 1 = very good to 4 = bad. A sufficient anesthetic level (> or = 3) after rectal premedication was reached in 86% in midazolam/S(+)-ketamine premedicated children, in 75% in midazolam premedicated children, but only in 30% in S(+)-ketamine premedicated children (P < 0.05 S(+)-ketamine versus midazolam/S(+)-ketamine and midazolam groups). The incidence of side effects after rectal premedication was rare. Whereas the mask acceptance score was comparable in the three study groups, a 25% rate of complications during anesthesia induction via face was observed in the S(+)-ketamine study group (P < 0.05 versus other study groups). Our conclusions are that S(+)-ketamine for rectal premedication in the dose we chose shows a poor anesthetic effect and a frequent incidence of side effects during induction of anesthesia via face mask compared with the combination of midazolam/S(+)-ketamine and plain midazolam. Dose-response studies of S(+)-ketamine for rectal premedication in pediatric anesthesia may be warranted.

Aggressive warming reduces blood loss during hip arthroplasty.

UNLABELLED: We evaluated the effects of aggressive warming and maintenance of normothermia on surgical blood loss and allogeneic transfusion requirement. We randomly assigned 150 patients undergoing total hip arthroplasty with spinal anesthesia to aggressive warming (to maintain a tympanic membrane temperature of 36.5 degrees C) or conventional warming (36 degrees C). Autologous and allogeneic blood were given to maintain a priori designated hematocrits. Blood loss was determined by a blinded investigator based on sponge weight and scavenged cells; postoperative loss was determined from drain output. Results were analyzed on an intention-to-treat basis. Average intraoperative core temperatures were warmer in the patients assigned to aggressive warming (36.5 degrees +/- 0.3 degrees vs 36.1 degrees +/- 0.3 degrees C, P< 0.001). Mean arterial pressure was similar in each group preoperatively, but was greater intraoperatively in the conventionally warmed patients: 86+/-12 vs 80+/-9 mm Hg, P<0.001. Intraoperative blood loss was significantly greater in the conventional warming (618 mL; interquartile range, 480-864 mL) than the aggressive warming group (488 mL; interquartile range, 368-721 mL; P: = 0.002), whereas postoperative blood loss did not differ in the two groups. Total blood loss during surgery and over the first two postoperative days was also significantly greater in the conventional warming group (1678 mL; interquartile range, 1366-1965 mL) than in the aggressively warmed group (1,531 mL; interquartile range, 1055-1746 mL, P = 0.031). A total of 40 conventionally warmed patients required 86 units of allogeneic red blood cells, whereas 29 aggressively warmed patients required 62 units (P = 0.051 and 0.061, respectively). We conclude that aggressive intraoperative warming reduces blood loss during hip arthroplasty. IMPLICATIONS: Aggressive warming better maintained core temperature (36.5 degrees vs 36.1 degrees C) and slightly decreased intraoperative blood pressure. Aggressive warming also decreased blood loss by approximately 200 mL. Aggressive warming may thus, be beneficial in patients undergoing hip arthroplasty.

Nocturnal panic and trauma.

We examined the recollection of traumas in panic disorder patients with and without history of nocturnal panic attacks. From a sample of 154 patients seeking treatment for panic disorder, almost 85% of those with nocturnal panic reported a history of traumatic events in comparison to only 28% without nocturnal panic. Fear of loss of vigilance is considered as a potential mediator of the relationship between nocturnal panic and traumatic events.

Shivering and shivering-like tremor during labor with and without epidural analgesia.

BACKGROUND: Effective treatment and prevention of hyperthermia and shivering-like tremor during labor is hindered by a poor understanding of their causes. The authors sought to identify the incidence of nonthermoregulatory shivering-like tremor and the factors associated with this activity. METHODS: The authors studied women in spontaneous full-term labor who chose epidural analgesia (n = 21) or opioid sedation (n = 31). Shivering-like tremor and sweating were evaluated by observation. Core temperature was recorded in the external auditory canal using a compensated infrared thermometer. Arteriovenous shunt tone was evaluated with forearm minus fingertip skin temperature gradients; gradients less than 0 were considered evidence of vasodilation. Tremor was considered nonthermoregulatory when core temperature exceeded 37 degrees C and the arms were vasodilated. Pain was evaluated using a visual analog scale. RESULTS: Shivering-like tremor was observed in 18% of 290, 30-min data-acquisition epochs before delivery. The patients were both normothermic and vasodilated during 15% of these epochs. Shivering was observed in 16% of 116 postdelivery epochs and was nonthermoregulatory in 28%. Sweating was observed in 30% of predelivery epochs, and the patients were both hypothermic and vasoconstricted during 12%. The mean core temperature in patients given epidural analgesia was approximately 0.2 degrees C greater than in those given sedation. Hyperthermia was observed during 10 epochs (38.4+/-0.3 degrees C) during epidural analgesia and during 10 epochs (38.4+/-0.3 degrees C) with sedation. The patients were vasoconstricted in more than 50% of these epochs in each group. Multivariate mixed-effects modeling identified high pain scores and vasoconstriction as significant predictors of shivering. There were no predictors for shivering epochs in patients who were simultaneously normothermic and vasodilated. Significant predictors of sweating were time before delivery, high pain scores, hypothermia with vasoconstriction, high thermal comfort, and low mean skin temperature. There were no predictors for sweating epochs in patients who were simultaneously hypothermic and vasoconstricted. CONCLUSIONS: This study confirms the clinical impression that some peripartum shivering-like tremor is nonthermoregulatory. The authors also identified nonthermoregulatory sweating. These data indicate that shivering-like tremor and sweating in the peripartum period is multifactorial.