Kaname Ueda

Reversibility of rocuronium-induced profound neuromuscular block with sugammadex in younger and older patients

BACKGROUND This study compared the reversibility of rocuronium-induced profound neuromuscular block with sugammadex in younger and older patients. METHODS Fifteen younger (20-50 yr) and 15 older (≥70 yr) patients were sequentially enrolled in this study. After induction of anaesthesia and laryngeal mask insertion, contraction of the adductor pollicis muscle in response to ulnar nerve stimulation was quantified using acceleromyography during 1.0-1.5% end-tidal sevoflurane and remifentanil anaesthesia. All patients initially received rocuronium 1 mg kg(-1), followed by 0.02 mg kg(-1) when a post-tetanic count (PTC) of 1 or 2 was observed. After completion of surgery, at reappearance of 1-2 PTC, the time required for a single bolus dose of 4 mg kg(-1) sugammadex to produce recovery to a train-of-four (TOF) ratio of 0.9 was recorded. RESULTS There were no differences in the total dose of rocuronium administered between the younger [mean (sd): 93.4 (17.5) mg] and the older [97.5 (32.2) mg] groups. In all patients, adequate recovery of the TOF ratio to 0.9 was achieved after administration of sugammadex, although it was significantly slower in the older [3.6 (0.7) min, P<0.0001] than in the younger group [1.3 (0.3) min]. There were no clinical events attributable to recurarization. CONCLUSIONS Sugammadex can adequately restore neuromuscular function in older patients, although a longer time is required to recover from profound rocuronium-induced neuromuscular block than in younger patients.

Successful Pain Management of Primary and Independent Spread Sites in a Child with CRPS Type I Using Regional Nerve Blocks

Dear Editor, A 14-year-old girl reported severe pain of the left first toe after a sprain of the left ankle joint when she was 9 years old. She complained of continuous pain in her chest, back, abdomen, and left first toe. The pain at all the sites was of a burning type with intensity of 6 on the numerical rating pain scale. She was unable to walk due to pain. Mechanical allodynia was present. Redness and swelling were recognized over the left first toe. …

The Effects of Flumazenil After Midazolam Sedation on Cerebral Blood Flow and Dynamic Cerebral Autoregulation in Healthy Young Males.

Background: It is unknown whether flumazenil antagonizes the decrease in cerebral blood flow or the alteration in dynamic cerebral autoregulation induced by midazolam. We, therefore, investigated the effects on cerebral circulation of flumazenil administered after midazolam, to test our hypothesis that, along with complete reversal of sedation, flumazenil antagonizes the alterations in cerebral circulation induced by midazolam. Methods: Sixteen healthy young male subjects received midazolam followed by flumazenil. The modified Observer’s Assessment of Alertness/Sedation (OAA/S) scale and bispectral index (BIS) were used to assess levels of sedation/awareness. For evaluation of cerebral circulation, steady-state mean cerebral blood flow velocity (MCBFV) was measured by transcranial Doppler ultrasonography. In addition, dynamic cerebral autoregulation was assessed by spectral and transfer function analysis between mean arterial pressure (MAP) variability and MCBFV variability. Results: During midazolam sedation, defined by an OAA/S score of 3 (responds only after name is called loudly and/or repeatedly), BIS, steady-state MAP, steady-state CBFV, and transfer function gain decreased significantly compared with baseline. After flumazenil administration, an OAA/S score of 5 (responds readily to name spoken in a normal tone) was confirmed. Then, BIS and MAP returned to the same level as baseline. However, steady-state MCBFV showed a further significant decrease compared with that under midazolam sedation, and the decreased transfer function gain persisted. Conclusions: Contrary to our hypothesis, the present results suggest that despite complete antagonism of the sedative effects of midazolam, flumazenil would not reverse the alterations in cerebral circulation induced by midazolam.

Sustained mild hypergravity reduces spontaneous cardiac baroreflex sensitivity

Head-to-foot gravitational force >1G (+Gz hypergravity) augments venous pooling in the lower body and reduces central blood volume during exposure, compared with 1Gz. Central hypovolemia has been reported to reduce spontaneous cardiac baroreflex sensitivity. However, no investigations have examined spontaneous cardiac baroreflex sensitivity during exposure to sustained mild +Gz hypergravity. We therefore hypothesized that mild +Gz hypergravity would reduce spontaneous cardiac baroreflex sensitivity, compared with 1Gz. To test this hypothesis, we examined spontaneous cardiac baroreflex sensitivity in 16 healthy men during exposure to mild +Gz hypergravity using a short-arm centrifuge. Beat-to-beat arterial blood pressure (tonometry) and R-R interval (electrocardiography) were obtained during 1Gz and 1.5Gz exposures. Spontaneous cardiac baroreflex sensitivity was assessed by sequence slope and transfer function gain. Stroke volume was calculated from the arterial pressure waveform using a three-element model. All indices of spontaneous cardiac baroreflex sensitivity decreased significantly (up slope: 18.6±2.3→12.7±1.6ms/mmHg, P<0.001; down slope: 19.0±2.5→13.2±1.3ms/mmHg, P=0.002; transfer function gain in low frequency: 14.4±2.2→10.1±1.1ms/mmHg, P=0.004; transfer function gain in high frequency: 22.2±7.5→12.4±3.5ms/mmHg, P<0.001). Stroke volume decreased significantly (88±5→80±6ml, P=0.025). Moreover, although systolic arterial pressure variability increased, R-R interval variability did not increase. These results suggest that even mild +Gz hypergravity reduces spontaneous cardiac baroreflex sensitivity, increasing the risk of cardiovascular disturbance during the exposure.

Antagonistic effect of flumazenil after midazolam sedation on arterial-cardiac baroreflex.

Flumazenil is generally administered to antagonise the sedative effect of midazolam. However, although flumazenil completely antagonises the sedative effect of midazolam, a few effects remain unantagonised. Hence, it is unclear whether flumazenil restores the attenuation of the arterial‐cardiac baroreflex (i.e. arterial‐heart rate reflex) induced by midazolam. We investigated the antagonistic effect of flumazenil administered after midazolam on cardiac baroreflex, to reveal whether complete recovery from midazolam‐induced sedation by flumazenil administration is accompanied by restoration of midazolams attenuating effects on the cardiac baroreflex.

Does ultrasound-guided rectus sheath block reduce abdominal pain in patients with postherpetic neuralgia?

To the Editor Postherpetic neuralgia (PHN), one cause of severe neuropathic pain, is believed to result from both peripheral and central sensitization of herpes zoster. Clinically, antidepressants and anticonvulsants are recommended as the first line of treatment for PHN. However, the analgesic effect of these medications is limited, and nerve blocks, including epidural nerve block and root block, are used to reduce the pain and abnormal sensation such as allodynia associated with PHN. We recently treated a patient with PHN on the abdomen by ultrasound-guided rectus sheath block. We obtained the patient’s written consent to report this case. A 71-year-old man reported 1 year of severe pain on the left side of the abdomen after herpes zoster (T-11 area). He had been treated with antidepressants and anticonvulsants without much success and was referred to our pain clinic. At the initial clinical visit, he complained of a burning, continuous pain on his left abdomen (T-8–T-11 area) with an intensity of 78 mm (out of 100) on a visual analog pain scale. His pain was limited between his anterior axillar line and the midline. The pain increased with movement and touching the area and was severe enough to interfere with his sleep. Mechanical allodynia was also present without any sensory loss at the painful area. After analyzing his clinical course and characteristics, the patient was diagnosed with PHN. Ultrasound-guided rectus sheath block was planned, and with the patient in the supine position, a 22-gauge, 70-mm short bevel nerve block needle (Plexufix , B. Braun Melsungen AG, Melsungen, Germany) was inserted approximately 5 cm left lateral from his umbilicus under ultrasound guidance using a linear probe (MicroMaxx , SonoSite Inc., Bothell, WA; HFL38 13 to 6 MHz linear probe), and 20 mL of 0.3% ropivacaine was injected to the periposterior rectus abdominis area. Ultrasonography showed local anesthetic spread between T-7 and T-12 segments. Fifteen minutes after the injection, the patient’s spontaneous pain and mechanical allodynia disappeared completely. Analgesia was confirmed between T-8 and T-11 segments by pinprick. At the 1-month follow-up, the patient’s pain had reduced to 25 mm on a visual analog pain scale, and mechanical allodynia had decreased. Therefore, an ultrasound-guided rectus sheath block was repeated 3 times at 14-day intervals, after which the pain and mechanical allodynia disappeared completely at the 3-month follow-up. No side effects were observed during the nerve block treatments. Ultrasound-guided rectus sheath block has several advantages in comparison with conventional nerve blocks including epidural nerve block. First, local anesthetics can be directly applied to peripheral nerves in the region of pain. Second, high concentrations of local anesthetics can be used. Third, the spread of applied local anesthetics can be confirmed by ultrasonography. Additional studies including proper controls are needed to confirm efficacy and safety of ultrasound-guided rectus sheath block in patients with abdominal pain due to PHN.

Dose-Effect Relationship Between Mild Levels of Hypergravity and Autonomic Circulatory Regulation.

INTRODUCTION The dose-effect relationships between different levels of hypergravity (>+1.0 Gz) and steady-state hemodynamic parameters have been reported in several studies. However, little has been reported on the dose-effect relationship between hypergravity levels and estimates of autonomic circulatory regulation, such as heart rate variability, arterial pressure variability, and spontaneous cardiac baroreflex sensitivity. We investigated dose-effect relationships between hypergravity levels from +1.0 Gz to +2.0 Gz (Δ0.5 Gz) and autonomic circulatory regulation to test our hypothesis that autonomic circulatory regulation has a linear relationship with hypergravity levels. METHODS Using a short-arm human centrifuge, 10 healthy seated men were subjected to +1.0 Gz, +1.5 Gz, and +2.0 Gz hypergravity. We evaluated steady-state hemodynamic parameters and autonomic circulatory regulation indices. Heart rate variability, arterial pressure variability, and spontaneous cardiac baroreflex sensitivity between arterial pressure and R-R interval variabilities were assessed by spectral analysis, sequence analysis, and transfer function analysis. RESULTS Steady-state heart rate, stroke volume, and sequence slope (indicating spontaneous cardiac baroreflex sensitivity in response to rapid changes in arterial pressure) showed linear correlations with increases in gravity (from +1.0 Gz to +2.0 Gz). On the other hand, steady-state cardiac output, steady-state systolic arterial pressure, and low-frequency power of diastolic arterial pressure (indicating peripheral vasomotor sympathetic activity) remained unchanged with gravity increases. CONCLUSION Contrary to our hypothesis, the present study suggested that autonomic circulatory regulations show complex changes with hypergravity levels. Spontaneous cardiac baroreflex sensitivity reduces in a dose-dependent manner from +1.0 Gz to +2.0 Gz, whereas peripheral vasomotor sympathetic activity seems to be maintained.

Incidence and prognosis of persistent pain induced by venipuncture for blood sampling: an observational study over a 5-year period.

OBJECTIVE The purpose of this study was to determine the incidence and prognosis of persistent and neuropathic pain induced by venipuncture for blood sampling in clinical practice. DESIGN & SETTING We investigated the incidence of persistent and neuropathic pain after venipuncture for blood sampling and evaluated the prognosis of patients with neuropathic pain at Nihon University Itabashi Hospital, Japan, based on an observational study. SUBJECTS Outpatients who required venipuncture for blood sampling at the laboratory room of Nihon University Itabashi Hospital between 2004 and 2008 were included as study subjects. RESULTS In the present study, of the 587,551 venipunctures performed at our hospital between 2004 and 2008, the incidences of persistent and neuropathic pain after venipuncture were 1 in every 4,418 venipunctures (133/587,551) and 1 in every 30,923 venipunctures (19/587,551), respectively. All the 19 patients who were identified as having neuropathic pain recovered completely. CONCLUSIONS We demonstrated that the incidence of persistent pain after venipuncture for blood sampling is low and that its prognosis is good.