Comparison between the coronal diameters of the cervical spinal canal and spinal cord measured using computed tomography and magnetic resonance imaging in Korean patients / 대한마취과학회지

Background@#If the proportion of the spinal cord in the epidural space can be determined under C-arm fluoroscopy during cervical epidural block, a safe entry point for the epidural needle can be established. The aim of this study was the measurement of the cord to canal transverse diameter ratio of each cervical spines. @*Methods@#We retrospectively evaluated the imaging data of 100 patients who underwent both cervical computed tomography (CT) and cervical magnetic resonance imaging (MRI) at our hospital. We measured the diameters of the spinal canal and spinal cord from the 3rd cervical vertebra to the 1st thoracic vertebra (T1) at each level by using the patients’ cervical CT and MRI images. The spinal cord and spinal canal diameters were measured in the transverse plane of the cervical MRI and CT images, respectively. @*Results@#The spinal cord to spinal canal diameter ratio was the highest at the 4th and 5th cervical vertebrae (0.64 ± 0.07) and the lowest at T1 (0.55 ± 0.06, 99% CI [0.535, 0.565]. @*Conclusions@#Our findings suggest that the cord to canal transverse diameter ratio could be used as a reference to reduce direct spinal cord injuries during cervical epidural block under C-arm fluoroscopy. In the C-arm fluoroscopic image, if an imaginary line connecting the left and right innermost lines of the pedicles of T1 is drawn and if the needle is inserted into the outer one-fifth of the left and right sides, the risk of puncturing the spinal cord would be relatively reduced.

Fluid management in patients undergoing neurosurgery

Fluid management is an important component of perioperative care for patients undergoing neurosurgery. The primary goal of fluid management in neurosurgery is the maintenance of normovolemia and prevention of serum osmolarity reduction. To maintain normovolemia, it is important to administer fluids in appropriate amounts following appropriate methods, and to prevent a decrease in serum osmolarity, the choice of fluid is essential. There is considerable debate about the choice and optimal amounts of fluids administered in the perioperative period. However, there is little high-quality clinical research on fluid therapy for patients undergoing neurosurgery. This review will discuss the choice and optimal amounts of fluids in neurosurgical patients based on the literature, recent issues, and perioperative fluid management practices.

Perioperative management of left ventricular diastolic dysfunction and heart failure: an anesthesiologist's perspective / 대한마취과학회지

Anesthesiologists frequently see asymptomatic patients with diastolic dysfunction or heart failure for various surgeries. These patients typically show normal systolic function but abnormal diastolic parameters in their preoperative echocardiographic evaluations. The symptoms that are sometimes seen are similar to those of chronic obstructive pulmonary disease. Patients with diastolic dysfunction, and even with diastolic heart failure, have the potential to develop a hypertensive crisis or pulmonary congestion. Thus, in addition to conventional perioperative risk quantification, it may be important to consider the results of diastolic assessment for predicting the postoperative outcome and making better decisions. If anesthesiologists see female patients older than 70 years of age who have hypertension, diabetes, chronic renal disease, recent weight gain, or exercise intolerance, they should focus on the patient's diastologic echocardiography indicators such as left atrial enlargement or left ventricular hypertrophy. In addition, there is a need for perioperative strategies to mitigate diastolic dysfunction-related morbidity. Specifically, hypertension should be controlled, keeping pulse pressure below diastolic blood pressure, maintaining a sinus rhythm and normovolemia, and avoiding tachycardia and myocardial ischemia. There is no need to classify these diastolic dysfunction, but it is important to manage this condition to avoid worsening outcomes.

The effect of nerve preservation methods on rat sciatic nerve structures studied with Synchrotron small-angle X-ray scattering (SAXS)

BACKGROUND: Synchrotron small-angle X-ray scattering (SAXS) is a very useful technique for experimental study of the nano-structure of the nervous system of animals. The study was designed to evaluate nerve preservation methods for the measurement of SAXS patterns. METHODS: Normal sciatic nerves extracted from male Sprague- Dawley rats were preserved in saline (N = 2), formalin (N = 2) or liquid nitrogen (N = 2) for 1 day, followed by measurement of SAXS patterns. SAXS patterns of normal sciatic nerves (N = 3) extracted just before the initiation of the experiment were used as controls. The study was carried out using the 4C1 beamline at Pohang Accelerator Laboratory in Korea. Incoming X-rays were monochromatized at 11 keV using a double multilayer (WB4C) monochromator with beam size of approximately 0.5 (V) × 0.8 (H) mm2. The exposure time was set at 60 sec, and 8 to 12 images per sample were acquired at a 0.5 mm interval. RESULTS: The periodic peaks of interfibrillar space between collagen fibrils were undetectable. The periodic peaks of the myelin sheath and collagen fibers were weakly detected or undetected in the nerves preserved in normal saline or formalin. The periodic peaks and intensity of the myelin sheath, collagen fibers, and interfibrillar space between collagens in the nerves preserved in liquid nitrogen were comparable to those of nerves in the ex vivo state. CONCLUSIONS: The study results indicated that preservation of nerves in liquid nitrogen is adequate for measurements with SAXS. However, saline and formalin preservation techniques were inadequate for SAXS measurement.

Adequate analgesic regimen would be required after minimally invasive colorectal surgery

No abstract available.

Structural analysis of a ligatured rat sciatic nerve in the ex vivo state using synchrotron small-angle X-ray scattering (SAXS)

BACKGROUND: To understand the fundamentals of neural tissue injury, experiments on the nano-structured nerve system of animals are essential. This study was designed to reveal the nanostructure changes of an isolated ligatured rat sciatic nerve using the synchrotron small-angle X-ray scattering (SAXS) technique. METHODS: Male Sprague-Dawley rats (weighing approximately 250 grams) were used in this study. The SAXS patterns of 1 week after ligatured nerves (N = 5) and the normal sciatic nerves (N = 5) for the control were acquired after extracted approximately 15 mm before the experiment. Experiments were conducted at the 4C1 beam line at the Pohang Accelerator Laboratory in Korea. The exposure time was 60 sec, and 8 to 12 images per sample were acquired in 0.5 mm intervals, including the regions above, around and below the ligatured position. RESULTS: The periodic peaks of the myelin sheath and the interfibrillar space of collagen completely disappeared at the ligatured position. Farther from the ligatured point, weak and quite different SAXS patterns were observed for the myelin sheath and interfibrillar space. However, the collagen fiber peaks appeared at all positions, although they were weaker near the ligatured position. CONCLUSIONS: The ligature treatment totally destroyed the myelin sheath and interfibrillar space of collagen. In addition, retrograde degeneration developed 2 mm above the ligatured site. The myelin sheath and interfibrillar space of collagen were damaged 6 mm below the ligatured site. However, the collagen fiber structure was not significantly affected by the ligature, indicating a much different structural organization.

Adsorption of desflurane by the silica gel filters in breathing circuits: an in vitro study / 대한마취과학회지

BACKGROUND: During general anesthesia, a heated breathing circuit (HBC) is used to replace the heat and moisture exchange function of the upper airway. One HBC uses an air dryer filter that employs silica gel (SG) as a desiccant. SG is capable of adsorbing many organic compounds. Therefore, we undertook an in vitro study of the adsorption of desflurane by SG filters. METHODS: An HBC was connected to an anesthesia machine, and a test lung was connected to the circuit. The test lung was mechanically ventilated with 2 or 4 L/min of fresh gas flow, with and without the air dryer filter. Desflurane was administered at a 6 vol% on the vaporizer dial setting. The experiment was repeated 15 times in each group. The end-tidal concentrations were measured during the experiments. The air dryer filter weights were measured before and after the experiments, and the times required to achieve the specific end-tidal desflurane concentrations were determined. RESULTS: Significant differences in the end-tidal concentrations of desflurane were observed between the control and filter groups (P < 0.001). The filter weights increased significantly after the experiments (P < 0.001). The times required to achieve the same end-tidal desflurane concentrations were different with the application of the air dryer filter (P < 0.001). CONCLUSIONS: The adsorption of desflurane with the use of an air dryer filter was verified in this in vitro study. Careful attention is needed when using air dryer gel filters during general anesthesia.

Peripheral nerve injury caused by needle impalement: Synchrotron small-angle X-ray scattering study in ex-vivo rat sciatic nerve

BACKGROUND: Direct puncture by a needle is a risk factor for nerve damage. This study was designed to demonstrate nerve damage caused by a needle using the synchrotron small-angle X-ray scattering (SAXS) technique. METHODS: A 15 mm section of rat (Male Spargue-Dawley, about 250 grams) sciatic nerves were involved in this study. The nerve specimen for the experiment (N = 5) was punctured 5 times by a needle (25 G, 100 beveled) under general anesthesia with enflurane. The needle was placed perpendicular to the nerve and the needle bevel was placed parallel to the nerve. The SAXS patterns of the punctured nerves, extracted about 15 min prior to the experiment, were acquired after 1 week. The SAXS patterns of a normal sciatic nerve (N = 5), extracted about 15 min prior to the experiment, were measured in order to provide a comparison. Experiments were carried out at 4C1 beamline at Pohang Accelerator Laboratory in Korea. Incoming X-rays were monochromatized at 11 keV using a double multilayer (WB4C) monochromator; the beam size was around 0.5 (V) x 0.8 (H) mm2. The exposure time was 60 sec, and 8 to 12 images were acquired per sample with a 0.5 mm interval. RESULTS: In the punctured group, the periodic peaks of myelin sheath and collagen fiber were not changed. However, the periodic peaks of interfibrillar distance of collagen were greatly changed. CONCLUSIONS: Direct needle-nerve impalement did not cause damages in myelin sheath and collagen fibers when the needle was placed perpendicular and the needle bevel paralleled to the nerve fiber. This result can imply that the needle slipped into the interfibrillar packing of collagen fibrils.

Re-evaluation of the applicability of ketamine in neurosurgical anesthesia

Traditionally, Ketamine has been considered to be contraindicated in neurosurgical patients due to the risk of intracranial hypertension. The evidence for this contraindication originated from early case reports and case-control studies which were inadequately designed and controlled. However, several recent articles indicate that ketamine can be safely used in traumatic brain injured patients treated with mechanical ventilation and that there is no significant increase in the intracranial pressure (ICP). Ketamine is an N-methyl-D-aspartate antagonist. It is believed to provide neuroprotection through a reduction in the glutamate excitotoxicity. This evidence is based on in vitro and animal studies. However, studies about its neuroprotective effects in humans are scarce. Data to recommend ketamine as first-line anesthetics for neurosurgery are insufficient, but ketamine as an adjuvant anesthetic agent may have benefits for neurosurgical patients, such as traumatic head injured patients with unstable hemodynamics. Therefore, ketamine should not be considered as absolutely contraindicated for neurosurgical patients and adequately powered, high-quality randomized controlled studies are needed to provide clinical evidences.

Role of calcium channels responsible for phenylephrine-induced contraction in rat aorta 3 days after acute myocardial infarction / 대한마취과학회지

BACKGROUND: Phenylephrine (PE) produces tonic contraction through involvement of various calcium channels such as store-operated calcium channels (SOCCs) and voltage-operated calcium channels (VOCCs). However, the relative contribution of each calcium channel to PE-induced contraction has not been investigated in isolated rat aorta of early acute myocardial infarction (AMI). METHODS: Endothelium-denuded rat aortic rings from rats 3 days after AMI or sham-operated (SHAM) rats were prepared in an organ chamber with Krebs-Ringer bicarbonate solution for isometric tension recording. We assessed the PE dose-response relationships in 2.5 mM calcium medium for both groups. The same procedure was repeated using rings pretreated with the SOCC inhibitor 2-aminoethoxydiphenyl borate, sarco/endoplasmic-reticulum calcium ATPase inhibitor thapsigargin (TG), diacyl glycerol lipase inhibitor RHC80267, and sodium-calcium exchanger inhibitor 3,4-dichlorobenzamil hydrochloride for 30 minutes before addition of calcium. When ongoing tonic contraction was sustained, dose-response curves to the VOCC inhibitor nifedipine were obtained to assess the relative contribution of each calcium channel under various conditions. RESULTS: The effect of SOCC induction with TG pretreatment on PE-induced contraction was significantly lower in the AMI group compared to the SHAM group. In addition, there were significant decreases in the sensitivity and efficacy of the VOCC inhibitor nifedipine on PE-induced contraction in the AMI group. CONCLUSIONS: Results suggest that the change of vascular reactivity of PE in rat aorta 3 days after AMI is characterized by a decreased contribution of L-type VOCCs. The enhanced VOCC-independent calcium entry mechanisms after AMI can be mediated by enhanced capacitative calcium entry through the activation of SOCCs.

Rocuronium-induced withdrawal movement: influence of ketorolac or a combination of lidocaine and ketorolac pretreatment / 대한마취과학회지

BACKGROUND: Pain on injection of rocuronium is a common clinical problem. We compared the efficacy of lidocaine, ketorolac, and the 2 in combination as pretreatment for the prevention of rocuronium-induced withdrawal movement. METHODS: For this prospective, randomized, placebo-controlled, double-blind study a total of 140 patients were randomly allocated to one of 4 treatment groups to receive intravenously placebo (saline), lidocaine (20 mg), ketorolac (10 mg), or both (n = 35 for each group), with venous occlusion. The tourniquet was released after 2 min and anesthesia was performed using 5 mg/kg thiopental sodium followed by 0.6 mg/kg rocuronium. The withdrawal response was graded on a 4-point scale in a double-blind manner. RESULTS: The overall incidence of withdrawal movements after rocuronium was 34.3% with lidocaine (P = 0.001), 40% with ketorolac (P = 0.004), and 8.6% with both (P < 0.001), compared with 74.3% with placebo. There was a significantly lower incidence of withdrawal movements in patients receiving the lidocaine/ketorolac combination than in those receiving lidocaine or ketorolac alone (P = 0.009 and 0.002, respectively). The incidence of moderate to severe withdrawal movements was 14.3% with lidocaine, 17.2% with ketorolac, and 2.9% with lidocaine/ketorolac combination, as compared to 45.7% with the placebo. There was no significant difference in withdrawal movement between the lidocaine group and the ketorolac group. CONCLUSIONS: Ketorolac pretreatment had an effect comparable to that of lidocaine in attenuating rocuronium-induced withdrawal movements and the lidocaine/ketorolac combination pretreatment, compared with lidocaine or ketorolac alone, effectively reduced withdrawal movements during rocuronium injection.

Massive hemothorax immediately after removal of central venous catheter: A case report / 대한마취과학회지

Hemothorax is a possible immediate complication of central venous catheterization. We experienced a patient who suffered from massive hemothorax 72 hours after right subclavian venous catheterization. A 29-year-old female patient with Marfan's syndrome underwent the Bentall's operation and aortic arch replacement with an artificial graft, which was performed uneventfully. She recovered favorably in the intensive care unit and was transferred to the general ward on postoperative day 3. Immediately after the removal of the catheter in the general ward, massive hemothorax developed and emergent thoracotomy should have been performed to control bleeding. We report this case to re-emphasize the careful monitoring even after removal of central venous catheter and the need for ultrasound guidance during insertion of central venous catheters.

Cardiac arrest with pulseless electrical activity during a robot-assisted distal gastrectomy: A case report

A 59-year-old woman was scheduled to undergo a robot-assisted distal gastrectomy under general anesthesia. During the operation, the vital signs were maintained in normal range. After 7 hours of surgery, the pulse oxymeter graph became flat and the end tidal CO2 concentration suddenly decreased. Palpation of the carotid artery revealed no heart beat but the EKG continued to show sinus rhythm. Pulseless electrical activity (PEA) was diagnosed. An advanced cardiopulmonary life support protocol for PEA was immediately initiated, which included chest compressions and doses of IV cardiovascular drugs. However, in spite of continuous CPR, the heart wasn't recovered from the arrest. We experienced cardiac arrest for pulseless electrical activity during robot-assisted distal gastrectomy.

The effect of the intravenous phenylephrine on the level of spinal anesthesia / 대한마취과학회지

BACKGROUND: Spinal anesthesia causes hypotension and bradycardia due to sympathetic nerve block and it is difficult to predict the level of sensory block and the duration of blockade. Recent studies have reported that intravenous phenylephrine can reduce the rostral spread of spinal anesthesia in pregnant women. We think a phenylephrine infusion will be useful for maintaining the baseline blood pressure by reducing the rostral spread of spinal anesthesia during the elective surgery of non-obstetric patients. METHODS: Sixty patients who were undergoing urologic surgery were randomized into two groups: Group C (the control group without phenylephrine) and Group P (with the addition of phenylephrine). After a bolus infusion of 50 microg phenylephrine following the spinal injection, phenylephrine was continuously infused at the rate of 200 microg/hr. We compared the dermatomal spreads of spinal anesthesia, the hemodynamic parameters (blood pressure, heart rate) and the incidences of hypotension between the two groups. RESULTS: At 20 minutes, the level of the upper dermatome blocked against cold sensation was a median of T8 (interquartile range: T8-T10) for the phenylephrine group, as compared with T4 (interquartile range: T4-T6) for the control group (P < 0.001). CONCLUSIONS: Intravenous phenylephrine can decrease the rostral spread of spinal anesthesia during urologic surgery.

Contralateral allodynia and central change in the chronic post-ischemic pain model rats / 대한마취과학회지

BACKGROUND: Mirror-image allodynia is a mysterious phenomenon that occurs in association with many clinical pain syndromes including complex regional pain syndromes (CRPS). Underlying mechanisms for the development of such pain are still a matter of investigation. Several studies suggest that activation of the N-methyl-D-aspartate (NMDA) receptor is essential for central sensitization as a base for persistent pain. The aim is to assess whether alteration of NMDA receptor expression correlates with the contralateral allodynia in the chronic post-ischemia pain (CPIP) model rats representing CRPS-Type I. METHODS: Application of a tight-fitting tourniquet for a period of 3 hours before reperfusion produced CPIP in male Sprague-Dawley rats. The mechanical paw withdrawal thresholds to von Frey stimuli (using a dynamic plantar aesthesiometer) were measured as pain indicators in ipsilateral and contralateral hindpaws. Phosphorylation of the NMDA receptor 1 subunit (pNR1), assessed with Western blot, was measured in the contralateral L4-6 spinal cord. RESULTS: Ipsilateral and contralateral mechanical allodynia is present at 4 hours after reperfusion, peaked at 3 days, and continued for 7 days after reperfusion. The relative density of pNR1 of CPIP rats significantly decreased in the contralateral L4-6 spinal cord compared to baseline value (P < 0.05). There was significant correlation between paw withdrawal threshold and the relative density of pNR1 (ipsilateral; R2 = 0.75, P < 0.01, contralateral; R2 = 0.60, P < 0.01). CONCLUSIONS: These data suggest that pNR1 is correlated to the contralateral mechanical allodynia in CPIP rats.