Real-time Monitoring of Cerebral Blood Flow and Cerebral Oxygenation During Rapid Ventricular Pacing in Neurovascular Surgery: A Pilot Study.

BACKGROUND: Rapid ventricular pacing (RVP) can be used to produce short periods of flow arrest during dissection or rupture of a cerebral aneurysm but carries the risk of inducing cerebral ischemia. This study evaluates the intraoperative effect of RVP on local cerebral blood flow (CBF) and cerebral oxygenation during neurovascular surgery. MATERIALS AND METHODS: Five patients undergoing elective cerebrovascular surgery were included in a single-center prospective study. RVP was applied in pacing periods of 40 seconds with 30% and 100% FiO2. Regional cerebral oxygenation was monitored using a Foresight near-infrared spectroscopy sensor. A Clark-type electrode and a thermal diffusion microprobe located in the white matter were used to monitor brain tissue pO2 and CBF, respectively. RESULTS: CBF response to RVP closely followed the blood pressure pattern and resulted in a low-flow state. Unlike CBF, brain tissue pO2 and regional cerebral oxygenation showed a delayed response to RVP, decreasing beyond the pacing period and slowly recovering after RVP cessation. We found a correlation between brain tissue pO2 and regional cerebral oxygenation. Increasing the inspired oxygen concentration had a positive impact on absolute regional cerebral oxygenation and brain tissue pO2 values, but the pattern resulting from applying RVP remained unaltered. CONCLUSIONS: RVP reduces CBF and cerebral oxygenation. Brain tissue pO2 and regional cerebral oxygenation are correlated but unlike CBF respond to RVP in a delayed manner. Further research is required to evaluate the impact of longer RVP bursts on brain oxygenation.

A low dose of three local anesthetic solutions for interscalene blockade tested by thermal quantitative sensory testing: a randomized controlled trial.

This randomized double-blind controlled trial compared the block characteristics of three low-dose local anesthetics at different roots in an ultrasound-guided interscalene block, using thermal quantitative sensory testing for assessing the functioning of cutaneous small nerve fibres. A total of 37 adults scheduled to undergo shoulder arthroscopy were randomized to receive 5 mL of either 0.5% levobupivacaine with and without epinephrine 1/200,000 or 0.75% ropivacaine in a single-shot interscalene block. Thermal quantitative sensory testing was performed in the C4, C5, C6 and C7 dermatomes. Detection thresholds for cold/warm sensation and cold/heat pain were measured before and at 30 min, 6, 10 and 24 h after infiltration around C5. The need for rescue medication was recorded. No significant differences between groups were found for any sensation (lowest P = 0.28). At 6 h, the largest differences in sensory thresholds were observed for the C5 dermatome. The increase in thresholds were less in C4 and C6 and minimal in C7 for all sensations. The analgesic effect lasted the longest in C5 (time × location mixed model P < 0.001 for all sensory tests). The time to rescue analgesia was significantly shorter with 0.75% ropivacaine (P = 0.02). The quantitative sensory findings showed no difference in intensity between the local anesthetics tested. A decrease in block intensity, with minimal changes in pain detection thresholds, was observed in the roots adjacent to C5, with the lowest block intensity in C7. A clinically relevant shorter duration was found with 0.75% ropivacaine compared to the other groups. Trial registration NCT 02691442.

Rapid Ventricular Pacing for Neurovascular Surgery: A Study on Cardiac and Cerebral Effects.

BACKGROUND AND OBJECTIVE: Intraoperative rupture of a cerebral aneurysm during neurosurgery can be a devastating event that increases perioperative morbidity and mortality. Rapid ventricular pacing (RVP) is a technique to obtain flow arrest for short periods of time during dissection or rupture of the aneurysm. The objective of this study was to evaluate the neurological and cardiac effects of repetitive periods of RVP during cerebrovascular surgery. METHODS: Data from patients who underwent repetitive RVP during craniotomy for cerebrovascular disorders were retrospectively analyzed from a single-center medical records database (Cegeka Medical Health Care Systems). We compared preoperative and postoperative troponin levels (cTnI) to assess cardiac ischemia. Preoperative and postoperative magnetic resonance imaging (MRI) results were screened for RVP-induced infarcts by evaluating diffusion restriction in the hemisphere contralateral to the operated side and the fossa posterior. RESULTS: A total of 37 patients were analyzed. An immediate decrease of systolic arterial blood pressure (<60 mm Hg) was achieved after initiation of RVP. Postoperative MRI did not reveal areas of diffusion restriction. RVP tended to be a predictor of postoperative cTnI increase. Preoperative and postoperative cTnI levels were higher in patients with a subarachnoid hemorrhage compared to patients without one. After 24 hours cTnI jevels normalized to preoperative values. CONCLUSIONS: Systolic arterial blood pressure decreased after RVP but normalized immediately when pacing stopped. MRI of the brain did not show RVP-related ischemia and the limited cTnI level increase normalized to preoperative values. Therefore, RVP during short periods of time seems to be a safe blood pressure-lowering technique for the brain and heart.

Pupillary dilation reflex and pupillary pain index evaluation during general anaesthesia: a pilot study.

BACKGROUND: Pupillary response by pupillary dilatation reflex (PDR) is a robust reflex, even measurable during general anaesthesia. However, the ability of infrared pupillometry to detect PDR differences obtained by intraoperative opioid administration in anaesthesized patients remains largely unknown. We analyzed the performance of automated infrared pupillometry in detecting differences in pupillary dilatation reflex response by a inbuilt standardized nociceptive stimulation program in patients under general anesthesia with a standardized propofol/fentanyl scheme. METHODS: In this single center, interventional cohort study 38 patients (24-74 years) were enrolled. Patients were anesthetized with propofol until loss of consciousness. Two dynamic pupil measurements were performed in each patient (before opioid administration and after opioid steady state). Automated infrared pupillometry was used to determine PDR during nociceptive stimulations (10-60 mA) applied by a inbuilt pupillary pain index protocol (PPI) to the skin area innervated by the median nerve. Increasing stimulations by protocol are device specific and automatically performed until pupil dilation of > 13%. Pupil characteristics, blood pressure, heart rate values were collected. RESULTS: After opioid administration, patients needed a higher stimulation intensity (45.26 mA vs 30.79 mA, p = 0.00001). PPI score showed a reduction after analgesic treatment (5.21 vs 7.68, p = 0.000001), resulting in a 32.16% score reduction. CONCLUSIONS: PDR via automated increased tetanic stimulation may reflect opioid effect under general anaesthesia. Further research is required to detect possible confounding factors such as medication interaction and optimization of individualized opioid dosage.

Effects of Stellate Ganglion Block on Analgesia Produced by Cervical Paravertebral Block as Established by Quantitative Sensory Testing: A Randomized Controlled Trial.

Objective: To use quantitative sensory testing (QST) to assess whether a stellate ganglion block (SGB) modulates the analgesia induced by cervical paravertebral block (CPVB). Design: A prospective double-blind randomized controlled trial. Setting: Department of Anesthesia, Antwerp University Hospital, October 2011 to December 2015. Subjects: Twenty-eight adults scheduled for arthroscopy of a nonfractured shoulder were enrolled. Methods: Participants were randomly assigned to receive either single CPVB (5 mL of levobupivacaine 0.5%) or combined CPVB + SGB (5 mL and 3 mL of levobubivacaine 0.5%, respectively). The detection thresholds for cold/warm sensations and cold/heat pain were established using thermal QST on the C4-C7 dermatomes before local anesthetic infiltration and at 0.5, 6, 10, and 24 hours thereafter. Our primary outcome was the time course of QST thresholds for the different neurosensitive/nociceptive modalities. As secondary and tertiary outcomes, we evaluated the degree of motor block and the time to first administration of rescue analgesics. Results: We randomized 20 patients. There were no significant differences in the detection thresholds for the neurosensitive/nociceptive modalities, motor block, or timing for rescue analgesics between the groups (P = 0.15-0.94). All patients with CPVB + SGB exhibited Horner's signs, whereas patients in the CPVB group did not exhibit these signs; however, this does not exclude sympathetic block. Conclusions: We were unable to demonstrate any analgesic benefit of CPVB + SGB in arthroscopic shoulder surgery. It is therefore not unreasonable to suppose that pain from soft tissue injuries without bony lesions is transmitted mainly by somatic nerves with no or only minimal involvement of the sympathetic nervous system.

Conus medullaris trauma: is there a greater risk in parturients?

BACKGROUND: There is some evidence that anaesthetists often perform neuraxial blocks at a higher lumbar interspace than intended. It may be questioned whether parturients are at greater risk for neurological damage when the dura is perforated at a more cephalad interspace than L2-L3. METHODS: Thirty-six patients scheduled for elective Caesarean delivery under CSE anaesthesia were selected for study. Using a B-D Durasafe Adjustable needle combination, the skin-to-epidural distance and the width of the epidural space were measured and matched with 36 female patients undergoing the same anaesthetic technique for orthopaedic procedures. RESULTS: Pregnant patients had a higher bodyweight (77 vs. 67 kg, p = 0.007) than those scheduled for orthopaedic surgery. The skin-to-epidural distance was similar in both groups (5.3 vs. 5.1 cm, p = 0.3). The width of the epidural space was 1.1 mm larger in parturients (8.2 vs. 7.1 mm, p = 0.04). More patients in this group had tip-to-tip distances exceeding 10 mm (25 vs. 12%). CONCLUSION: The greater epidural space or tip-to-tip distance between the epidural and spinal needle points in term parturients results in a lower margin of safety with respect to the distance from the dura to spinal cord or conus medullaris. Puncturing the correct interspace is, therefore, of crucial importance in pregnant patients.

Thermal quantitative sensory testing to assess the sensory effects of three local anesthetic solutions in a randomized trial of interscalene blockade for shoulder surgery.

PURPOSE: This study investigated whether quantitative sensory testing (QST) with thermal stimulations can quantitatively measure the characteristics of an ultrasound-guided interscalene brachial plexus block (US-ISB). METHODS: This was a prospective randomized trial in patients scheduled for arthroscopic shoulder surgery under general anesthesia and US-ISB. Participants and observers were blinded for the study. We assigned the study participants to one of three groups: 0.5% levobupivacaine 15 mL, 0.5% levobupivacaine 15 mL with 1:200,000 epinephrine, and 0.75% ropivacaine 15 mL. We performed thermal QST within dermatomes C4, C5, C6, and C7 before infiltration and 30 min, six hours, ten hours, and 24 hr after performing the US-ISB. In addition, we used QST, a semi-objective quantitative testing method, to measure the onset, intensity, duration, extent, and functional recovery of the sensory block. We also measured detection thresholds for cold/warm sensations and cold/heat pain. RESULTS: Detection thresholds for all thermal sensations within the ipsilateral C4, C5, C6, and C7 dermatomes increased rapidly (indicating the development of a hypoesthetic state) and reached a steady state after 30 min. This lasted for approximately ten hours and returned to normal detection thresholds by 24 hr. There were no differences detected between the three groups at 24 hr when we compared warm sensation thresholds on one dermatome. Visual inspection of the pooled results per dermatome suggests the ability of QST to detect clinically relevant differences in block intensity per dermatome. CONCLUSIONS: Quantitative sensory testing can be useful as a method for detecting the presence and characteristics of regional anesthesia-induced sensory block and may be used for the evaluation of clinical protocols. The three local anesthetic solutions exhibited a similar anesthetic effect. The results support the use of QST to assess block characteristics quantitatively under clinical research conditions. This trial was registered at Clinicaltrals.gov, NCT02271867.

Regional anaesthesia and postoperative analgesia techniques for spine surgery - a review.

The use of regional anaesthesia techniques for intra-operative anaesthesia and postoperative analgesia remains very controversial for patients scheduled to undergo spinal interventions. Spine surgeries, especially the most extensive types, are mostly performed under general anaesthesia. This has to be explained by the position required during surgery, the preference of the surgeon and/or anaesthesiologist and lack of sufficient literature supporting locoregional anaesthesia. In addition, there is an increasing trend to prefer general anaesthesia for spinal surgery. Nevertheless, with respect to spine surgeries more than 80% of the actual literature on neuraxial blocks is dated less than 12 years. The present overview was focused in the first place on the feasibility of (loco) regional techniques to be used intra-operatively. These techniques are also of interest for postoperative analgesia, either with a single bolus injection of local anaesthetics, opioids and adjuvants, alone or in combination, in continuous or intermittent administration and requiring the presence of foreign material in the neighborhood of the surgical field. As all techniques described offered variable success rates, future research is mandatory to determine their superiority over general intra-operative anaesthesia and conventional pain therapy with paracetamol, NSAIDs, opioids used alone or in combination.

Electromyographic activity of the diaphragm during neostigmine or sugammadex-enhanced recovery after neuromuscular blockade with rocuronium: a randomised controlled study in healthy volunteers.

BACKGROUND: The use of neuromuscular blocking agents has been associated with severe postoperative respiratory morbidity. Complications can be attributed to inadequate reversal, and reversal agents may themselves have adverse effects. OBJECTIVE: To compare the electromyographic activity of the diaphragm (EMGdi) during recovery from neuromuscular blockade using neostigmine and sugammadex. The hypothesis was that there would be better neuromuscular coupling of the diaphragm when sugammadex was used. DESIGN: A randomised, controlled, parallel-group, single-centre, double-blinded study. SETTING: District general hospital in Belgium. PARTICIPANTS: Twelve healthy male volunteers. INTERVENTIONS: Individuals were anaesthetised with propofol and remifentanil. After rocuronium 0.6 mg kg, a transoesophageal electromyography (EMG) recorder was inserted. For reversal of neuromuscular blockade, volunteers received sugammadex 2 mg kg (n = 6) or neostigmine 70 µg kg (n = 6). MAIN OUTCOME MEASURES: EMGdi, airway pressure and flow were continuously measured during weaning from the ventilator until tracheal extubation. Arterial blood gas samples were obtained for PaO2 and PaCO2 analysis at the first spontaneous breathing attempt and after tracheal extubation. RESULTS: During weaning, 560 breaths were retained for analysis. The median (95% CI) peak EMGdi was 1.1 (0.9 to 1.5) µV in the neostigmine group and 1.6 (1.3 to 1.9) µV in the sugammadex group (P < 0.001). Individuals in the neostigmine group had 125 of 228 (55%) breaths with associated EMGdi at least 1 µV vs. 220 of 332 (66%) breaths in the sugammadex group (P = 0.008). The median (95% CI) tidal volume was 287 (256 to 335) ml after neostigmine and 359 (313 to 398) ml after sugammadex (P = 0.013). The median (95% CI) PaO2 immediately after extubation was 30.5 (22.8 to 37.1) kPa after sugammadex vs. 20.7 (12.9 to 27.5) kPa after neostigmine (P = 0.03). CONCLUSION: EMGdi, tidal volume and PaO2 following tracheal extubation were increased after sugammadex compared with neostigmine, reflecting diaphragm-driven inspiration after sugammadex administration. Sugammadex may free more diaphragmatic acetylcholine receptors than neostigmine, which has an indirect effect. TRIAL REGISTRATION: EudraCT ref: 2013-002078-30.

Optic nerve sheath diameter remains constant during robot assisted laparoscopic radical prostatectomy.

BACKGROUND: During robot assisted laparoscopic radical prostatectomy (RALRP), a CO2 pneumoperitoneum (CO2PP) is applied and the patient is placed in a head-down position. Intracranial pressure (ICP) is expected to acutely increase under these conditions. A non-invasive method, the optic nerve sheath diameter (ONSD) measurement, may warn us that the mechanism of protective cerebrospinal fluid (CSF) shifts becomes exhausted. METHODS: After obtaining IRB approval and written informed consent, ONSD was measured by ocular ultrasound in 20 ASA I-II patients at various stages of the RALRP procedure: baseline awake, after induction, after applying the CO2PP, during head-down position, after resuming the supine position, in the postoperative anaesthesia care unit, and on day one postoperatively. Cerebral perfusion pressure (CPP) was calculated as the mean arterial (MAP) minus central venous pressure (CVP). RESULTS: The ONSD did not change during head-down position, although the CVP increased from 4.2(2.5) mm Hg to 27.6(3.8) mm Hg. The CPP was decreased 70 min after assuming the head-down position until 15 min after resuming the supine position, but remained above 60 mm Hg at all times. CONCLUSION: Even though ICP has been documented to increase during CO2PP and head-down positioning, we did not find any changes in ONSD during head-down position. These results indicate that intracranial blood volume does not increase up to a point that CSF migration as a compensation mechanism becomes exhausted, suggesting any increases in ICP are likely to be small.

Case report: inadvertent intrathecal placement of a pulmonary artery catheter introducer.

We present a case of unintended intrathecal cannulation by a pulmonary artery catheter introducer in a patient scheduled for coronary surgery. This complication was likely due to multiple attempts of placing the guidewire. Switching to the straight tip of the guidewire may have created a false route, facilitating entrance in the subarachnoid space. A lumbar intrathecal catheter was placed to maintain a low pressure at the cervical dural puncture site by draining 10 mL cerebrospinal fluid per hour. After removal of the lumbar drain, the patient experienced symptoms consistent with postdural puncture headache. Magnetic resonance imaging of the spine could not reveal the location of the possible leak. A lumbar epidural blood patch alleviated all complaints. One month later the patient underwent surgery successfully. We hypothesize that ultrasound imaging may have prevented this complication.

Lidocaine 5% patch for localized neuropathic pain: progress for the patient, a new approach for the physician.

Neuropathic pain (NeP) syndromes remain a difficult-to-treat medical entity. Despite a growing number of pharmacological and invasive analgesic therapies the results remain less than optimal because of insufficient analgesic efficacy and/or occurrence of pronounced side effects. Current guidelines propose the use of multimodal and balanced pharmacological therapies, focused on the underlying pathophysiological mechanisms (mechanistic approach). Lidocaine 5% patches are a new treatment option currently licensed for the treatment of postherpetic neuralgia. However, these patches can also be used for the treatment of different types of superficial NeP syndromes, such as diabetic polyneuropathy. Their therapeutic success, however, largely depends on the correct identification of appropriate patients and pain syndromes. This manuscript outlines the correct identification of patients and proper use of these patches in order to ensure as much as possible the therapeutic efficacy of this new treatment option.

Management of neuropathic pain after surgical and non-surgical trauma with lidocaine 5% patches: study of 40 consecutive cases.

OBJECTIVE: To determine the efficacy of lidocaine 5% patches [Versatis, commercialised by Grünenthal GmbH, Aachen, Germany] in patients with PNCCP. BACKGROUND: This study focuses on chronic pain states of a neuropathic nature, located at the scar or over a larger area of the skin around the scar. This post-operative/post-traumatic neuropathic chronic cutaneous pain (PNCCP) may be a side-effect of any incision of the skin in the context of a surgical procedure or a traumatic event. RESEARCH DESIGN AND METHODS: A single-centre, open, non-randomised, prospective study was performed in a university hospital referral centre for patients with chronic neuropathic pain after surgical or non-surgical trauma. Forty consecutive patients with chronic PNCCP, a VAS score > or =5, a LANSS score > or =12, and a stable consumption of pain medication were prospectively evaluated. All patients were given lidocaine 5% patches, following a 12 h on/off schedule. MAIN OUTCOME MEASURES: Visual analogue scale (VAS) and the Leeds Assessment of Neuropathic Symptoms and Signs (LANSS) scorings were performed pretreatment (day 0), on the 28th day (4 weeks), and after 84 days (12 weeks). RESULTS: The mean pretreatment VAS score (VAS(0)) was 7.225 +/- 1.209, and the mean pretreatment LANSS score (LANSS(0)) was 18.60 +/- 2.610. The number of patients with a VAS score <5 at the latest follow-up (VAS(84)) was 21 (52.5%). Mean VAS(84) was 4.625 +/- 1.675. Seventeen patients (42.5%) had a LANSS score <12 at the latest follow-up. Overall mean LANSS(84) was 12.85 +/- 3.093. CONCLUSION: Lidocaine 5% patches seem to be an effective treatment of post-surgical and post-traumatic pain. These results should be supported with randomised and placebo-controlled studies with larger sample sizes and longer follow-ups.

Corrected scoliosis, cholinesterase deficiency, and cesarean section: a case report.

We describe a patient with severe scoliosis for which corrective surgery was performed at the age of 12. During a previous caesarean section under general anaesthesia pseudocholinesterase deficiency was discovered. Ultrasound guided spinal anaesthesia was performed enabling a second caesarean section under loco-regional anaesthesia.

Altered sensitivity to mechanical stimulation during prolonged subcutaneous administration of endothelin-1 in rats.

Cancer pain is often difficult to treat. Growing evidence indicates that chemical mediators secreted by the tumor itself play an important role in the development of cancer pain. One such mediator, endothelin-1 (ET-1) is secreted by different tumor types. Studies have indicated that ET-1 induces spontaneous and evoked nociception in rodents and in humans. The focus of all these studies has always been on a single administration of ET-1. Such an acute exposure to ET-1 however bears little resemblance to the clinical condition in which cancer patients are exposed continuously for many months to increased levels of ET-1. To improve the knowledge of the pathological role of ET-1 in cancer, we developed an animal model of prolonged exposure to ET-1. Rats were exposed to subcutaneous administration of ET-1 for seven consecutive days, with a total amount of 67.4 nmol. On days +2, +3, +5, +7, and +10 sensitivity to von Frey hairs and to pin-prick stimulation were evaluated. Prolonged administration of ET-1 induced signs of mechanical allodynia on several time points. Although the administered doses were very small, prolonged administration of ET-1 seems to lead to a state of mechanical allodynia.

Abdominal cutaneous nerve entrapment syndrome after blunt abdominal trauma in an 11-year-old girl.

Chronic abdominal pain is a common complaint in children. Pain originating from the abdominal wall is often overlooked. Nevertheless, recognizing this type of pain prevents unnecessary examinations (Editorial: Abdominal wall tenderness test: could Carnett cut costs? Lancet. 1991, 337:1134). Abdominal cutaneous nerve entrapment syndrome (ACNES) is a relatively unknown cause of abdominal wall pain in children. Simple questions and clinical tests, which are discussed in this report, can give a direct clue to this disease. The treatment also is equally simple and effective. We describe an 11-year-old girl with ACNES after blunt abdominal trauma, what we believe has not been reported before. Abdominal wall pain, for example, caused by ACNES, as other types of chronic pain, has a serious impact on a child's well-being and future coping mechanisms with disease and health behavior.

Levobupivacaine-sufentanil with or without epinephrine during epidural labor analgesia.

In a prospective, randomized, double-blind study, we investigated whether epinephrine increased the efficacy of levobupivacaine and sufentanil during epidural labor analgesia. Seventy term parturients received an epidural injection of levobupivacaine 0.125% and sufentanil 0.75 microg/mL with or without 1:800,000 epinephrine. After an initial dose of 10 mL, a patient-controlled analgesia pump was started. Total and hourly drug consumption, pain scores using the visual analog scale, sensory and motor block, duration of labor, vital variables, maternal and neonatal outcome, and side effects were compared. If the parturients experienced insufficient pain relief during the study, even after a rescue dose of 10 mL, they were excluded from further study and received 10 mL of bupivacaine 0.125% and sufentanil 0.75 microg/mL with 1:800,000 epinephrine. Hourly drug consumption, rescue dosing, and pain scores at 15 min and 20 min were lower in the epinephrine group. The incidence of motor block and duration of the second stage of labor tended to be higher in the epinephrine group and were associated with lower Apgar scores at 1 and 5 min. These findings suggest that the addition of epinephrine intensifies the effects of epidural levobupivacaine and sufentanil but may cause more motor block.

Sublingual piroxicam for postoperative analgesia: preoperative versus postoperative administration: a randomized, double-blind study.

Nonsteroidal antiinflammatory drugs have been used to obtain preemptive analgesia. We investigated, in this randomized, double-blind study, whether sublingual (s.l.) piroxicam given before was more effective than that given after surgery. Fifty-two patients scheduled for laparoscopic bilateral inguinal hernia repair under general anesthesia were enrolled. Group PRE (25 patients) received 40 mg of piroxicam s.l. 2 h before surgery and a placebo 10 min after surgery. Group POST (27 patients) were treated with a placebo 2 h before surgery and received 40 mg of piroxicam s.l. 10 min after surgery. After an initial dose of 100 mg tramadol IV, patient-controlled analgesia with tramadol was started and recorded. Visual analog scores were assessed in the recovery and at 6, 20, and 30 h postoperatively. Significantly lower visual analog scores were found in group PRE at 6 and 20 h. Significantly smaller cumulative tramadol consumption was observed after 30 h in group PRE. In summary, our findings suggest that preoperative s.l. piroxicam is more effective than the postoperative administration. Because of the low pain scores in both groups, the clinical relevance of these findings is not clear from this study.