Relationship between PaO₂/FiO₂ and number of regions with B-line on transthoracic lung ultrasound: a prospective, observational study

BACKGROUND: Aeration of the lungs must be monitored during general anesthesia because of the possibility of postsurgical pulmonary complications. The aim of this study was to compare PaO₂/FiO₂ and the number of regions with B-line on transthoracic lung ultrasonography (TLU) between the postinduction and postsurgical periods. METHODS: Twenty-six adult patients undergoing major abdominal surgery were enrolled. Arterial blood gas analysis and TLU were performed 30 min after the induction of anesthesia (postinduction) and after skin closure (postsurgical period) while patients were under mechanical ventilation. TLU was performed in 12 regions (anterior, lateral, and posterior in the upper and lower regions of both lungs). The number of regions with B-line was counted. RESULTS: Compared with postinduction values, the number of regions with B-line on TLU was increased in the postsurgical period (0.3 ± 0.5 to 1.3 ± 1.2, P < 0.001); however, PaO₂/FiO₂ did not significantly differ (421.3 ± 95.8 to 425.2 ± 86.0, P = 0.765). The change in PaO₂/FiO₂ (postinduction-postsurgical period) was significantly higher in Group B than in Group A (P = 0.028). CONCLUSIONS: Although the number of regions with B-line on TLU was increased in the postsurgical period, lung oxygenation did not differ, based on the main assessment in this study. In contrast, patients with an increased number of regions with B-line tended to show a reduction in PaO₂/FiO₂ during the postsurgical period. Further study seems necessary to establish the number of regions with B-line on TLU as a tool for evaluation of perioperative oxygenation.

Erratum: Heart rate variability as a predictor of hypotension after spinal anesthesia in hypertensive patients / 대한마취과학회지

In the original article contained an error in Accepted date.

Heart rate variability as a predictor of hypotension after spinal anesthesia in hypertensive patients / 대한마취과학회지

BACKGROUND: Hypotension is a common phenomenon after spinal anesthesia in hypertensive patients. We investigated whether heart rate variability could predict the occurrence of hypotension after spinal anesthesia in hypertensive patients. METHODS: Forty-one patients undergoing spinal anesthesia were included. Heart rate variability was measured at five different time points such as before fluid loading (baseline), after fluid loading as well as 5 min, 15 min and 30 min after spinal anesthesia. Fluid loading was performed using 5 ml/kg of a crystalloid solution. Baseline total power and low to high frequency ratio (LF/HF) in predicting hypotension after spinal anesthesia were analyzed by calculating the area under the receiver operating characteristic curves (AUC). RESULTS: Moderate hypotension, defined as a decrease of mean arterial pressure to below 20-30% of the baseline, occurred in 13 patients and severe hypotension, defined as a decrease of mean arterial pressure greater than 30% below the baseline, occurred in 7 patients. LF/HF ratiosand total powers did not significantly change after spinal anesthesia. AUCs of LF/HF ratio for predicting moderate hypotension was 0.685 (P = 0.074), severe hypotension was 0.579 (P = 0.560) and moderate or severe hypotension was 0.652 (P = 0.101), respectively. AUCs of total power for predicting moderate hypotension was 0.571 (P = 0.490), severe hypotension was 0.672 (P = 0.351) and moderate or severe hypotension was 0.509 (P = 0.924), respectively. CONCLUSIONS: Heart rate variability is not a reliable predictor of hypotension after spinal block in hypertensive patients whose sympathetic activity is already depressed.

Comparison of meperidine and nefopam for prevention of shivering during spinal anesthesia / 대한마취과학회지

BACKGROUND: Shivering is a frequent event during spinal anesthesia and meperidine is a well-known effective drug for prevention and treatment of shivering. Nefopam is a non-opiate analgesic and also known to have an anti-shivering effect. We compared nefopam with meperidine for efficacy of prevention of shivering during spinal anesthesia. METHODS: Sixty five patients, American Society of Anesthesiologists physical status I or II, aged 20-65 years, scheduled for elective orthopedic surgery under spinal anesthesia were investigated. Patients were randomly divided into two groups, meperidine (Group M, n = 33) and nefopam (Group N, n = 32) groups. Group M and N received meperidine 0.4 mg/kg or nefopam 0.15 mg/kg, respectively, in 100 ml of isotonic saline intravenously. All drugs were infused for 15 minutes by a blinded investigator before spinal anesthesia. Blood pressures, heart rates, body temperatures and side effects were checked before and at 15, 30, and 60 minutes after spinal anesthesia. RESULTS: The incidences and scores of shivering were similar between the two groups. The mean arterial pressures in Group N were maintained higher than in Group M at 15, 30, and 60 minutes after spinal anesthesia. The injection pain was checked in Group N only and its incidence was 15.6%. CONCLUSIONS: We conclude that nefopam can be a good substitute for meperidine for prevention of shivering during spinal anesthesia with more stable hemodynamics, if injection pain is effectively controlled.

Hemodynamic effect of full flexion of the hips and knees in the supine position: a comparison with straight leg raising / 대한마취과학회지

BACKGROUND: Straight raising of the legs in the supine position or Trendelenburg positioning has been used to treat hypotension or shock, but the advantages of these positions are not clear and under debate. We performed a crossover study to evaluate the circulatory effect of full flexion of the hips and knees in the supine position (exaggerated lithotomy), and compare it with straight leg raising. METHODS: This study was a prospective randomized crossover study from the tertiary care unit at our university hospital. Twenty-two patients scheduled for off-pump coronary artery bypass surgery were enrolled. Induction and maintenance of anesthesia were standardized. Exaggerated lithotomy position or straight leg raising were randomly selected in the supine position. Hemodynamic variables were measured in the following sequence: 10 min after induction, 1, 5, and 10 min following the designated position, and 1 and 5 min after returning to the supine position. Ten min later, the other position was applied to measure the same hemodynamic variables. RESULTS: During the exaggerated lithotomy position, cerebral and coronary perfusion pressure increased significantly (P < 0.01) without a change in cardiac output. During straight leg raising, cardiac output increased at 5 min (P < 0.05) and cerebral and coronary perfusion pressures did not increase except for cerebral perfusion pressure at 1 min. However, the difference between the two groups at each time point in terms of cerebral perfusion pressure was clinically insignificant. CONCLUSIONS: Full flexion of the hips and knees in the supine position did not increase cardiac output but may be more beneficial than straight leg raising in terms of coronary perfusion pressure.

Update of sedation in view of Joint Commission International standards

Although the practice of sedation has markedly increased and expanded beyond the operating room with the development of new diagnostic and minimally invasive surgical procedures, there is no guideline for hospitals to set up a sedation policy in Korea. The Joint Commission International (JCI), which is a division of Joint Commission of United States, has urged Korean hospitals to develop guidelines for sedation. Because JCI defines the sedation standards as a minimum, there is much for Korean medical association and physicians in charge of sedation to do in order to improve the safety of sedated patients and set up an economical and efficient sedation system. There are three main requirements to meet JCI standards. Aqualified individual responsible for sedation should complete a formal training program supervised by an anesthesiologist or experienced practitioner, and adequate facilities and monitoring systems must be available to safely care for patients throughout sedation. Secondly, a documentation process around sedation, including informed consent, pre-operative assessment, the parameters observed during sedation, and discharge criteria, should be organized according to the sedation policy, which in turn should be determined by an institutional sedation committee. Lastly, JCI requires continuous quality improvement activity, which can improve the efficiency of the sedation process and the safety of sedation care. Multi-departmental joint discussion may be necessary to advance the practice of sedation and avoid conflicts among departments. This review aims to highlight the starting points of adiscussionon local standards for sedation.

Sedation under JCI standard / 대한마취과학회지

The practice of anesthesia and sedation continues to expand beyond the operating room and now includes the gastroenterology suite, magnetic resonance imaging suites, and the cardiac catheterization laboratory. Non-anesthesiologists frequently administer sedation, in part because of a lack of available anesthesiologists and economic aspect, which emphasizes the safety of sedation. The Joint Commission International (JCI) set a standard responding to this issue indicating that qualified individuals who have drug and monitoring knowledge as well as airway management skills can only administer sedating agents. In Korea, the Ministry of Health and Welfare developed new sedation standards for hospital evaluation, which is similar to the JCI standards. This review intends to help with the understanding of the JCI sedation standard and compare it to the Korean sedation standard.

The effect of beta1-adrenergic receptor gene polymorphism on prolongation of corrected QT interval during endotracheal intubation under sevoflurane anesthesia / 대한마취과학회지

BACKGROUND: The hemodynamic responses to endotracheal intubation are associated with sympathoadrenal activity. Polymorphisms in the beta1-adrenergic receptor (beta1AR) gene can alter the pathophysiology of specific diseases. The aim of this study is to investigate whether the Ser49Gly and Arg389Gly polymorphism of the beta1AR gene have different cardiovascular responses during endotracheal intubation under sevoflurane anesthesia. METHODS: Ninety-one healthy patients undergoing general anesthesia were enrolled. Patients underwent slow inhalation induction of anesthesia using sevoflurane in 100% oxygen. Vecuronium 0.15 mg/kg was given for muscle relaxation. Endotracheal intubation was performed by an anesthesiologist. The mean arterial pressure (MAP), heart rate (HR), and the corrected QT (QTc) interval were measured before induction, before laryngoscopy, and immediately after tracheal intubation. Genomic DNA was isolated from the patients' peripheral blood and then evaluated for the beta1AR-49 and beta1AR-389 genes using an allele-specific polymerase chain reaction method. RESULTS: No differences were found in the baseline values of MAP, HR, and the QTc interval among beta1AR-49 and beta1AR-389, respectively. In the case of beta1AR-49, the QTc interval change immediately after tracheal intubation was significantly greater in Ser/Ser genotypes than in Ser/Gly genotypes. No differences were observed immediately after tracheal intubation in MAP and HR for beta1AR-49 and beta1AR-389. CONCLUSIONS: We found an association between the Ser49 homozygote gene of beta1AR-49 polymorphism and increased QTc prolongation during endotracheal intubation with sevoflurane anesthesia. Thus, beta1AR-49 polymorphism may be useful in predicting the risk of arrhythmia during endotracheal intubation in patients with long QT syndrome.

Participation of KATP Channels in the Antinociceptive Effect of Pregabalin in Rat Formalin Test

BACKGROUND: Pregabalin is an anticonvulsant and analgesic agent that interacts selectively with the voltage-sensitive-Ca(2+)-channel alpha-2-delta subunit. The aim of this study was to evaluate whether the analgesic action of intrathecal (IT) pregabalin is associated with KATP channels in the rat formalin test. METHODS: IT PE-10 catheters were implanted in male Sprague-Dawley rats (250-300 g) under inhalation anesthesia using enflurane. Nociceptive behavior was defined as the number of hind paw flinches during 60 min after formalin injection. Ten min before formalin injection, IT drug treatments were divided into 3 groups: normal saline (NS) 20 microl (CON group); pregabalin 0.3, 1, 3 and 10 microg in NS 10 microl (PGB group); glibenclamide 100 microg in DMSO 5 microl with pregabalin 0.3, 1, 3 and 10 microg in NS 5 microl (GBC group). All the drugs were flushed with NS 10 microl. Immunohistochemistry for the KATP channel was done with a different set of rats divided into naive, NS and PGB groups. RESULTS: IT pregabalin dose-dependently decreased the flinching number only in phase 2 of formalin test. The log dose response curve of the GBC group shifted to the right with respect to that of the PGB group. Immunohistochemistry for the KATP channel expression on the spinal cord dorsal horn showed no difference among the groups 1 hr after the formalin test. CONCLUSIONS: The antinociceptive effect of pregabalin in the rat formalin test was associated with the activation of the KATP channel. However, pregabalin did not induce KATP channel expression in the spinal cord dorsal horn.

Ejaculatory Failure after Unilateral Neurolytic Celiac Plexus Block

Abdominal pain associated with chronic pancreatitis is often difficult to control with analgesics and can be severely debilitating with significant impairment of quality of life. In these patients, neurolytic celiac plexus block (NCPB) is an effective treatment option with a low complication rate. However, there is a risk of ejaculatory failure after NCPB, which may be a problem in patients with a long life expectancy. We report a case of ejaculatory failure after unilateral NCPB in a patient with chronic pancreatitis.

Ultrasonic doppler flowmeter-guided occipital nerve block / 대한마취과학회지

BACKGROUND: Greater occipital nerve block is used in the treatment of headaches and neuralgia in the occipital area. We evaluated the efficacy of ultrasonic doppler flowmeter-guided occipital nerve block in patients experiencing headache in the occipital region in a randomized, prospective, placebo-controlled study. METHODS: Twenty-six patients, aged 18 to 70, with headache in the occipital region, were included in the study. Patients received a greater occipital nerve block performed either under ultrasonic doppler flowmeter guidance using 1% lidocaine or the traditional method. Sensory examination findings in the occipital region were evaluated. RESULTS: The complete block rate of greater occipital nerve blockade in the doppler group was significantly higher than in the control group respectively (76.9% vs. 30.8%, P < 0.05). Only one patient in the control group had a complication (minimal bleeding). CONCLUSIONS: Ultrasonic doppler flowmeter-guided occipital nerve block may be a useful method for patients suffering headache in the occipital region.

Effect of various anesthetic induction agents on blood magnesium and calcium concentration / 대한마취과학회지

BACKGROUND: Decrease in blood magnesium and calcium concentration is associated with an increase in the incidence of arrhythmia, especially during the induction period. Therefore, it is important to evaluate the effects of propofol, pentothal sodium, and sevoflurane on calcium and magnesium concentration. METHODS: Thirty-six premedicated, ASA grade I patients were selected and randomly allocated into 3 groups. Six percent sevoflurane inhalation (sevo group), propofol 1.5 mg/kg (propofol group), and 5 mg/kg of pentothal sodium (pento group) were administered for anesthetic induction and anesthetic maintenance was done with end-tidal sevoflurane concentration at 3.5%. Blood sampling was performed during the pre-induction period (pre-induction), just before tracheal intubation (pre-intubation), and 2 min after intubation (post-intubation). pH corrected ionized magnesium and calcium were calculated and analyzed simultaneously. RESULTS: Both total calcium and magnesium concentrations decreased significantly in all groups during the pre-intubation and post-intubation periods compared with the pre-induction period. Ionized calcium only decreased significantly during pre-intubation and post-intubation in the pento group, and did not change throughout the study period in the sevo and propofol groups. Ionized magnesium did not change throughout the study period in any of the groups. pH corrected ionized calcium decreased significantly only at post-intubation in the pento group. CONCLUSIONS: All anesthetic induction agents administered in this study can be used safely in terms of magnesium-associated arrhythmia. However, ionized calcium concentration decreased in the pento group, but all values were within normal limits. This finding indicated that it is safe to use propofol, pentothal sodium, and sevoflurane for anesthetic induction

The Expression of the Ca++ Channel alpha2delta Subunit and TRPM8 in the Dorsal Root Ganglion of Sympathetically Maintained Pain and Sympathetic Independent Pain Rat Models / 대한통증학회지

BACKGROUND: Peripheral nerve injury induces up-regulation of the calcium channel alpha2delta (alpha2delta) subunit and TRPM8 in the dorsal root ganglion (DRG) which might contribute to allodynia development. We investigated the expression of the alpha2delta subunit and TRPM8 in the DRG of sympathetically maintained pain (SMP) and sympathetic independent pain (SIP) rat model. METHODS: For the SMP model, the L5 and L6 spinal nerves were ligated tightly distal to the DRG. For the SIP model, the tibial and sural nerves were transected, while the common peroneal nerve was spared. After a 7 day postoperative period, tactile and cold allodynia were assessed using von Frey filaments and acetone drops, respectively. Expression of the alpha2delta subunit and TRPM8 in the L5 and L6 DRG were subsequently examined by a Western blot. RESULTS: There were no significant differences between the two models for the thresholds of tactile and cold allodynia. Expression of the alpha2delta subunit in the ipsilateral DRG to the injury was increased as determined on a Western blot as compared to that in the contralateral or sham-operated DRG of the SMP model, but there was no difference in expression seen with the use of the SIP model. There was no difference in the expression of TRPM8 in the ipsilateral DRG to the injury and the contralateral or sham-operated DRG of either model. CONCLUSIONS: Up-regulation of the alpha2delta subunit in injured DRG may play a role that contributes to tactile allodynia development in SMP, but not TRPM8 to cold allodynia after peripheral nerve injury.

Short Term Outcomes and Prognostic Factors Based on Radiofrequency Thermocoagulation on Lumbar Medial Branches / 대한통증학회지

BACKGROUND: Lumbar zygapophysial joints are a common source of chronic lower back pain and radiofrequency thermocoagulation (RF) of the medial branches (MB) has been shown to be effective at providing substantial pain relief for chronic low back pain.Therefore, we carried out this study to determine the short term outcomes and prognostic factors of RF on the MB of patients with lumbar facet syndrome. METHODS: We performed RF in fourteen patients who showed greater than 80% pain relief up to three times after a diagnostic MB block was conducted using 0.3 ml of 0.5% bupivacaine.Using 10 cm curved electrodes with 10-mm active tip, a 60 second, 80 degrees C lesion was made after electrical stimulation at 50 Hz for sensory and 2 Hz for motor nerve testing.The degree of pain relief was then assessed after 2 weeks, and again after 3 months using a visual analog scale (VAS) and a four point Likert scale.The outcome was regarded as 'success' if at least a 50% reduction in the VAS was observed.Possible prognostic factors between the two groups were also evaluated. RESULTS: The success rate was 71.4% (10/14) after three months of follow-up. However, there were transient complications, such as neuritis like syndrome, in 4 patients. In addition, short symptom duration and low minimal voltage (< 0.4 V) for sensory stimulation were shown to be the relevant prognostic factors for a successful outcome. CONCLUSIONS: RF may be an alternative to repeated MB block or intraarticular injection for palliation of lumbar facet syndrome. For better outcomes, early diagnosis and strict patient selection should be coupled with efforts to avoid anatomically incorrect RF.

Antiallodynic Effect of Pregabalin in Rat Models of Sympathetically Maintained and Sympathetic Independent Neuropathic Pain

Pregabalin binds to the voltage-dependent calcium channel alphadelta subunit and modulates the release of neurotransmitters, resulting in analgesic effects on neuropathic pain. Neuropathic pain has both sympathetically maintained pain (SMP) and sympathetic independent pain (SIP) components. We studied the antiallodynic effects of pregabalin on tactile allodynia (TA) and cold allodynia (CA) in SMP-and SIP-dominant neuropathic pain models. Allodynia was induced by ligation of the L5 & L6 spinal nerves (SMP model) or by transection of the tibial and sural nerves (SIP model) in rats. For intrathecal drug administration, a PE-10 catheter was implanted through the atlantooccipital membrane to the lumbar enlargement. Pregabalin was administered either intraperitoneally (IP) or intrathecally (IT) and dosed up incrementally until an antiallodynic effect without sedation or motor impairment was apparent. TA was assessed using von Frey filaments, and CA was assessed using acetone drops. IP-administered pregabalin dose-dependently attenuated TA in both models and CA in the SMP model, but not CA in the SIP model. IT-administered pregabalin dose-dependently attenuated both TA and CA in both models. However, the dose response curve of IT-administered pregabalin in SMP was shifted to left from that of SIP and the ED50 of IT-administered pregabalin for CA in SMP was about 900 times less than that in SIP. These findings suggest that pregabalin exerts its antiallodynic effect mainly by acting at the spinal cord, and that IT-administered pregabalin has more potent antiallodynic effects in SMP. The alphadeltasubunit might be less involved in the CA in SIP.

The Prognostic Factors of Selective Transforaminal Epidural Block in Patients with Low Back Pain / 대한통증학회지

BACKGROUND: Selective transforaminal epidural block (STEB) has showen effectiveness as a diagnostic and therapeutic option for the management of patients with low back pain or sciatica. This study was carried out in order to determine the short-term effects and prognostic factors associated with STEB in patients with low back pain or sciatica. METHODS: Ninety-seven patients were selectedfor participation in this study. Their diagnosis were based werewason the clinical symptoms and MRI findings. We performed STEB under fluoroscopic guidance and injected 3 ml of radio opaque dye in order to confirm the technical success of the procedure. We then injected 20 mg of triamcinolone mixed into 3 ml of 0.5% mepivacaine. One month later, we classified the patient outcomes as excellent, good, moderate or poor, according to the degree of reduction in VAS score from baseline. The independent variables assessed included symptom duration, block level, number of blocks, primary diagnosis, prior caudal block, anterior epidural space filling of dye, medication history, demographic data, radiating pain, back surgery and spondylolisthesis. RESULTS: At a mean follow-up period of 1 month after STEB, excellent results were noted in the patients diagnosed with herniated lumbar disc (70%), non-specific spondylosis (54%), spinal stenosis (44%), and failed back syndrome (28%). The patients with epidural adhesion and combined spondylolisthesis were associated with poorer outcomes. Combined caudal block, symptom duration and the extent of epidural spread of the drug were not related to the effectiveness of the treatment. CONCLUSIONS: Selective transforaminal epidural block is effective in treating patients with radiculopathy, such as herniated lumbar disc, but it isrelatively ineffective in treating patients with structural deformities, such as failed back syndrome and spondylolisthesis.

The Analgesic Effects of Intrathecal Pregabalin in Rat Formalin Tests: Comparison between Pre- and Post-treatment / 대한마취과학회지

BACKGROUND: Pregabalin is an analog of gamma aminobutyric acid, and selectively interacts with the alpha-2-delta subunit of the voltage dependent calcium channels. The aims of this study were to investigate the analgesic effects of intrathecal pregabalin in rat formalin tests and to compare between the pre-treatment and post-treatment group. METHODS: All experimental animals were randomly divided into pre- and post-treatment groups. In pre-treatment groups, pregabalin (0.003g, 0.01g, 0.03g, 0.1g, n = 6 at each group) was administered through the intrathecal catheter 10 min prior to formalin injection. In post-treatment groups, pregabalin (0.01g, 0.03g, 0.1g, 0.3g, n = 6 at each group) was administered through the catheter 10 min after formalin injection. Formalin (50 ml, 5%) was injected in the left hind paw. We counted the number of flinching as a pain behavior for 60 min to quantify the nociceptive response. RESULTS: The withdrawal responses which were represented by flinching count, were decreased dose dependently in the phase 2, in all groups (pre-treatment and post-treatment group), while there were less analgesic effects and ceiling effects in the phase 1. There was more significant decreasing flinching number in the pre-treatment group than that in the post-treatment group. CONCLUSIONS: Intrathecal pregabalin has preemptive analgesic effect and may be useful in the management of inflammation induced hyperalgesia.

The Effect of 6% Hydroxyethyl Starch 130/0.4 on Hemostasis and Hemodynamic Efficacy in Off-pump Coronary Artery Bypass Surgery: a Comparison with 6% Hydroxyethyl Starch 200/0.5 / 대한마취과학회지

BACKGROUND: This study was designed to compare the effect of low-molecular 6% hydroxyethyl starch (HES) 130/0.4 on hemostasis and hemodynamic efficacy with that of medium-molecular 6% HES 200/0.5 in patients undergoing off-pump coronary artery bypass surgery. METHODS: Forty-eight patients were randomized to receive up to 33 ml/kg of either 6% HES 130/0.4 or 6% HES 200/0.5. Hemodynamic variables and blood tests including thromboelastography were measured 10 min after induction (baseline value, T0), 5 min after acute loading of HES 10 ml/kg (T1) in hypovolemic patients, after sternum closure (T2), and 16 hr after intensive care unit (ICU) arrival (T3). Chest tube drainage was recorded until 16 hours after ICU arrival. RESULTS: Hemodynamic variables were similar in both groups. Chest tube drainage at 16 hr after surgery was higher in HES 200/0.5 group than that in HES 130/0.4 group. Maximum clot firmness was decreased in HES 200/0.5 group at sternal closure but not in HES 130/0.4 group. CONCLUSIONS: Both HES 200/0.5 and HES 130/0.4 were equally efficient in maintaining stable hemodynamics during off-pump coronary artery bypass surgery. However, HES 130/0.4 may reduce postoperative blood loss compared to that of HES 200/0.5 at the same dose of 33 ml/kg.

The Interaction between Intrathecal NMDA Receptor Antagonist and 5-HT3 Receptor Agonist in the Rat Formalin Test / 대한마취과학회지

BACKGROUND: A single agent administered is not effective enough to block nociception. Combination of agents acting through different mechanisms may be one of the best ways for better analgesic methods. The purpose of this study was to investigate the spinally mediated analgesic interaction between 5-HT3 receptor agonist (m-CPBG) and NMDA receptor antagonist (MK801) in the rat formalin test. METHODS: A polyethylene catheter was inserted in the atlanto-occipital membrane to the thoracolumbar level of the spinal cord. On postoperative 7 day, the normal saline (n = 6), m-CPBG (10, 30, 100microgram: n = 18) and MK801 (0.1, 1, 10microgram: n = 18) were injected intrathecally before subcutaneous injection of 5% formalin. The combinations of each 1/2ED50 + 1/2ED50, 1/4ED50 + 1/4ED50, 1/8ED50 + 1/8ED50 were tested and the ED50 of the combination was determined. The experimental ED50 values were compared with the theoretical additive values. RESULTS: m-CPBG dose-dependently decreased the number of flinches in both phase 1 and 2. MK801 dose-dependently reduced the number of flinches in phase 2, but not in phase 1. The combination of m-CPBG and MK801 produced dose-dependent decreases of flinches on both phase 1 and 2. ED50 values (2.75microng for m-CPBG and 0.076microgram for MK801) of phase 2 in the combination were significantly less than the calculated additive values (20.0microgram for m-CPBG and 0.55microgram for MK801)(P<0.01). CONCLUSIONS: Intrathecally administered m-CPBG and MK801 had synergistic analgesic effects on formalin-induced hyperalgesia as well as antinociceptive effects in phase 1 on the rat formalin test.

The Changes of Blood Pressure, Heart Rate and Heart Rate Variability after Stellate Ganglion Block / 대한통증학회지

BACKGROUND: Stellate ganglion block (SGB) might be associated with changes in the blood pressure (BP) and heart rate (HR). The heart rate variability (HRV) shows the balance state between sympathetic and parasympathetic activities of the heart. The changes in these parameters of the HRV were studied to evaluate the possible mechanism of SGB in changing the BP. METHODS: SGB was performed on 26 patients, using a paratracheal technique at the C6 level, and 8 ml of 1% mepivacaine injected. The success was confirmed by check the Horner's syndrome. The BP, HR and HRV were measured before and 5, 15, 30, 45 and 60 minutes after the SGB. RESULTS: The increases in the BP from the baseline throughout the study period were statistically, but not clinically significant. The HR and LF/HF (low frequency/high frequency) ratio were increased at 5 and 45 min, respectively, after the administration of the SGB. In a comparison of left and right SGB, no significant differences were found in the BP, HR and HRV. A correlation analysis showed that an increased BP was significantly related with the changes in the LF/ HF ratio and LF at 15 and 30 minutes, respectively, after the SGB. Dividing the patients into two groups; an increased BP greater and less than 20% of that at the baseline INC and NOT groups, respectively, hoarseness occurred more often in the INC group (P = 0.02). CONCLUSIONS: It was concluded that SGB itself does not clinically increase the BP and HR in normal hemodynamic patients. However, the loss of balance between the sympathetic and parasympathetic nerve system, attenuation of the baroreceptor reflex and hoarseness are minor causes of the increase in the BP following SGB; therefore, further studies will be required.