Adenosine-assisted clipping of intracranial aneurysms.

Temporary parent vessel clip occlusion in aneurysm surgery is not always practical or feasible. Adenosine-induced transient cardiac arrest may serve as an alternative. We retrospectively reviewed our clinical database between September 2011 and July 2014. All patients who underwent microsurgical clipping of intracranial aneurysms under adenosine-induced asystole were included. A total of 18 craniotomies were performed, and 18 aneurysms were clipped under adenosine-induced asystole (7 basilar arteries, 8 internal carotid arteries, 1 middle cerebral artery, and 1 anterior communicating artery) in 16 patients (10 females, 6 males). Nine cases were elective and seven after subarachnoid hemorrhage. Mean age was 54 years (range 39-70). The indications for adenosine use were proximal control in narrow surgical corridors in 13 cases and "aneurysm softening" in 4 cases. A single dose was used in 14 patients; 3 patients had multiple boluses. The median (range) total dose was 30 (18-135) mg. Adenosine induced a bradycardia with concomitant arterial hypotension in all patients, and the majority also had asystole for 5-15 sec. Transient cardiac arrhythmias were noted in one patient (AFib in need of electroconversion after two boluses). Nine clinical scenarios where adenosine-induced temporary cardiac arrest and deep hypotension was an effective adjunct to temporary clipping during microsurgical clipping of intracranial aneurysms were identified.

The Shamrock lumbar plexus block: A dose-finding study.

BACKGROUND: The Shamrock technique is a new method for ultrasound-guided lumbar plexus blockade. Data on the optimal local anaesthetic dose are not available. OBJECTIVE: The objective of this study is to estimate the effective dose of ropivacaine 0.5% for a Shamrock lumbar plexus block. DESIGN: A prospective dose-finding study using Dixon's up-and-down sequential method. SETTING: University Hospital Orthopaedic Anaesthesia Unit. INTERVENTION: Shamrock lumbar plexus block performance and block assessment were scheduled preoperatively. Ropivacaine 0.5% was titrated with the Dixon and Massey up-and-down method using a stepwise change of 5 ml in each consecutive patient. Combined blocks of the femoral, the lateral femoral cutaneous and the obturator nerve were prerequisite for a successful lumbar plexus block. PATIENTS: Thirty patients scheduled for lower limb orthopaedic surgery completed the study. MAIN OUTCOME MEASURES: The minimum effective anaesthetic volume of ropivacaine 0.5% (ED50) to achieve a successful Shamrock lumbar plexus block in 50% of the patients. Further analysis of the data was performed with a logistic regression model to calculate ED95 and to estimate the effective doses for a sensory lumbar plexus block not requiring a motor block of the femoral nerve. RESULTS: The Dixon and Massay estimate of the ED50 was 20.4 [95% confidence interval (95% CI) 13.9 to 30.0] ml ropivacaine 0.5%. The logistic regression estimate of the ED95 was 36.0 (95% CI 19.7 to 52.2) ml ropivacaine 0.5%. For a sensory lumbar plexus block, the ED50 was 17.1 (95% CI 12.3 to 21.9) ml and the ED95 was 25.8 (95% CI 18.6 to 33.1) ml. CONCLUSION: A volume of 20.4 ml ropivacaine 0.5% provided a successful Shamrock lumbar plexus block in 50% of the patients. A volume of 36.0 ml would be successful in 95% of the patients. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT01956617.

Adding propacetamol to ketorolac increases the tolerance to painful pressure.

UNLABELLED: Combining an NSAID and paracetamol (acetaminophen) has in some studies given superior analgesia compared with the single drugs. In other trials no additive effect has been found. We have investigated the effect of this drug combination on the pressure pain tolerance threshold (PPTT), a reproducible correlate to clinical pain. The aim of this double blind, randomised, placebo controlled, crossover study was to evaluate the effect of i.v. propacetamol 2 g (= paracetamol 1 g) and ketorolac 30 mg, individually and in combination, on PPTT in 16 volunteers on four separate days. PPTT was measured 15 min before and at 45, 60, 90 and 150 min after the start of test drug administration. The pressure stimuli were applied on the base of a fingernail, increasing by 30 kPa/s until the pressure pain tolerance threshold was reached. For the total observation period (150 min), only the combination (propacetamol+ketorolac) increased significantly PPTT compared with baseline (P<0.04), while PPTT decreased significantly after placebo (P<0.01). The combination (propacetamol+ketorolac) and ketorolac alone increased PPTT compared with placebo (combination vs. placebo and ketorolac vs. placebo, P<0.001) and with propacetamol (combination vs. propacetamol and ketorolac vs. propacetamol, P<0.001). The combination was significantly better than ketorolac alone (P<0.04). After propacetamol 2 g, PPTT did not change significantly neither compared with placebo or baseline. CONCLUSIONS: Tolerance to repeated painful pressure (PPTT) decreased after placebo. Ketorolac 30 mg caused an increase in PPTT compared with placebo but not with baseline. Adding propacetamol 2 g to ketorolac 30 mg significantly increased PPTT. These findings support the practice of combining paracetamol with an NSAID for relief of acute pain.

Advantages and disadvantages of adrenaline in regional anaesthesia.

Adrenaline has been added to local anaesthetic solutions for more than a century. The aim has been to delay the absorption of the local anaesthetic drug and to prolong and enhance its anaesthetic effect, both in peripheral and central neuraxial blockades. The intention in this chapter has been to give up-to-date knowledge about adrenaline as an adjuvant to local anaesthetics and/or opioids in clinical peripheral and central blockades. My own research has focused on optimizing postoperative epidural analgesia by adding adrenaline and/or fentanyl to an epidural mixture with dilute bupivacaine or ropivacaine. The main part of this chapter will therefore focus on the advantages and disadvantages of adrenaline in epidural analgesia. However, recent knowledge about adrenaline in peripheral blockade will also be covered, together with some pharmaceutical comments on the shelf-life of local anaesthetic mixtures containing adrenaline.

Epinephrine markedly improves thoracic epidural analgesia produced by a small-dose infusion of ropivacaine, fentanyl, and epinephrine after major thoracic or abdominal surgery: a randomized, double-blinded crossover study with and without epinephrine.

UNLABELLED: We have shown that epinephrine markedly improves the analgesic effect of a thoracic epidural infusion of bupivacaine and fentanyl. Ropivacaine has an intrinsic vasoconstrictive effect, and epinephrine may therefore not have the same pharmacokinetic interaction in a ropivacaine-fentanyl infusion; but a possible spinal cord alpha(2)-agonist effect of epinephrine would give the same positive pharmacodynamic interaction with ropivacaine and fentanyl during epidural analgesia. In a prospective, randomized, crossover study, a thoracic epidural infusion of ropivacaine 1 mg/mL and fentanyl 2 microg/mL with or without epinephrine 2 microg/mL was given to 12 patients in a double-blinded manner after major thoracic or upper abdominal surgery. Main outcome measures were pain intensity at rest and when coughing, evaluated on a visual analog scale. Extent of sensory blockade was evaluated by determining dermatomal hypoesthesia to cold. Pain increased (P < 0.001) and hypoesthetic dermatomal segments decreased (P < 0.001) when epinephrine was omitted from the triple epidural infusion. After 3 h without epinephrine, pain intensity when coughing was unacceptable despite rescue analgesia. After restarting the triple epidural mixture with epinephrine, pain was again reduced to mild pain when coughing, and the sensory blockade was restored. The mixture with epinephrine caused less nausea and facilitated mobilization. We conclude that epinephrine improves the pain relief and reduces the side effects of a thoracic epidural infusion of ropivacaine and fentanyl after major thoracic or upper abdominal surgery. IMPLICATIONS: Epidural epinephrine markedly improves the pain relief and sensory blockade of a small-dose thoracic epidural infusion of ropivacaine and fentanyl. Nausea was reduced, and mobilization of the patients was facilitated.