Chul-Woo Jung

Influence of lumbar flexion on the position of the intercrestal line

Background and Objectives This study was performed to ascertain whether the position of the intercrestal line changes as a result of flexion of the lumbar spine. Methods Previously taken lumbar spine x-rays of 103 patients in the neutral and full-flexed positions were reviewed. In the lateral flexion images to compensate for the sagittal rotation of the pelvis during lumbar flexion and for the possible difference in the level between the two sides of the ilium when taking the lateral images, the intercrestal line was drawn as follows: a potential line, crossing the midpoint of the highest points of both iliums, should be perpendicular to the tangential line at the point of intersection of the potential line with the skin. The position of the intercrestal line in relation to the spinous process was determined on an imaginary line moved 1 cm toward the vertebral body from the tangential line on the 2 successive spinous processes, and the interspinous distance of L3-4 was measured on this imaginary line. Results With full-flexion of the lumbar spine, the position of the intercrestal line in relation to the spinous process [median (25th to 75th percentiles)] changed slightly from L4 (L4-L4-5) into L4-5 (L4-L4-5) (P < .001), but it remained at the same level in 58.3% of the patients (60/103). In no case was a change of more than 1 level observed. The interspinous width (mean ± SD) of L3-4 increased from 6.5 ± 2.4 mm to 13.2 ± 4.4 mm (P < .001). Conclusion When compared with the neutral position, the position of the intercrestal line usually does not change with full flexion of the lumbar spine, and even in cases in which change occurs, it does not move beyond the next level.

Epinephrine and phenylephrine pretreatments for preventing postreperfusion syndrome during adult liver transplantation

Acute hypotension after reperfusion of the liver graft occurs frequently during liver transplantation. A randomized, prospective trial was performed to test the effects of epinephrine and phenylephrine pretreatments for attenuating postreperfusion syndrome (PRS). Ninety‐three adult liver recipients were randomly allocated to receive an intravenous bolus of 10 μg of epinephrine, 100 μg of phenylephrine, or normal saline (the control group) at the time of graft reperfusion. The occurrence of PRS, the use of vasoactive drugs, and the postoperative courses were compared. The epinephrine and phenylephrine groups showed PRS less frequently (39% and 48%) than the control group (77%, P = 0.006) as well as higher mean arterial pressures (MAPs) immediately after reperfusion (P < 0.05). An overshoot of MAP was observed in one‐third of the pretreated patients with minimal heart rate changes. Only 2 patients in each pretreatment group showed an increase in MAP that was greater than 20% of the baseline value. The intraoperative epinephrine and dopamine requirements were significantly lower in both pretreatment groups. Perioperative laboratory data, postoperative stays, and in‐hospital mortality rates were similar for the 3 groups. In conclusion, pretreatment with 10 μg of epinephrine or 100 μg of phenylephrine significantly reduces the occurrence of PRS and vasopressor requirements without immediate or delayed adverse effects in adult liver transplantation. Liver Transpl, 2012.

Nafamostat Mesilate Attenuates Postreperfusion Syndrome during Liver Transplantation

Postreperfusion syndrome (PRS), an acute decrease in blood pressure after reperfusion of the liver graft, occurs frequently during liver transplantation surgery. We supposed that the activation of the kallikrein–kinin system leading to extensive systemic vasodilatation was a possible cause. The effect of pretreatment with nafamostat mesilate (NM), a broad spectrum serine protease inhibitor, on the occurrence of PRS was evaluated. Sixty‐two adult liver recipients were randomized to receive an intravenous bolus of either 0.02 mg/kg of NM (NM group, n = 31) or an equal volume of normal saline (control group, n = 31) just before reperfusion of the liver graft. Occurrence of PRS and intraoperative use of vasoactive drugs were compared between the two groups. Postoperative recovery was also compared. PRS was significantly less frequent (48% vs. 81%, p = 0.016) requiring less vasopressors in the NM group compared to the control group. The NM group also showed faster recovery of the mean arterial pressure. Perioperative laboratory values were similar between the two groups. Pretreatment with 0.02 mg/kg of NM immediately before reperfusion decreases the frequency of PRS and vasopressor requirements during the reperfusion period in liver transplantation.

The tenth rib line as a new landmark of the lumbar vertebral level during spinal block

The purpose of this study was to assess whether the tenth rib line (an imaginary line that joins the lowest points of the rib cage on the flanks) could be used as a marker of the lumbar vertebral level. Simple X‐rays (n = 100) were taken with radiopaque markers attached on the lowest points of the rib cage and the uppermost points of the iliac crests on both flanks. The spinous process or interspinous space that the tenth rib or Tuffiers lines crossed was identified and recorded, respectively, in the neutral and fully flexed positions. With lumbar flexion, the tenth rib line (median (25th to 75th percentiles)) moved upward (L2 (L1−2 − L2) vs. L1–2 (L1–2 – L1–2); p < 0.01), but Tuffiers line moved downward (L4−5 (L4 − L4−5) vs. L4−5 (L4 − L5); p < 0.01). Because the ease of palpating the tenth rib line and its distribution patterns are comparable to those of the Tuffiers line, the tenth rib line may be useful as a new landmark of the lumbar vertebral level as well as a safeguard to prevent spinal puncture from being mistakenly performed at a dangerously high level.

Effect of the bevel direction of puncture needle on success rate and complications during internal jugular vein catheterization

Objective: Artery puncture and hematoma formation are the most common immediate complications during internal jugular vein catheterization. This study was performed to assess whether the bevel-down approach of the puncture needle decreases the incidence of posterior venous wall damage and hematoma formation during internal jugular vein catheterization. Design: Prospective, randomized, controlled study. Setting: A university-affiliated hospital. Patients: Three hundred thirty-eight patients for scheduled for thoracic surgery requiring central venous catheterization in the right internal jugular vein. Interventions: Patients requiring internal jugular vein catheterization were enrolled and randomized to either the bevel-down group (n = 169) or the bevel-up group (n = 169). All patients were placed in the Trendelenburg position with the head turned to the left. After identifying the right internal jugular vein with ultrasound imaging, a double-lumen central venous catheter was inserted using the modified Seldinger technique. Venous entry of the needle was recognized by return of venous blood during needle advance or withdrawal. The internal jugular vein was assessed cross-sectionally and longitudinally after catheterization to identify any complications. A p value of <.05 was considered to be statistically significant. Measurements and Main Results: There was no difference in the incidence of the puncture-on-withdrawal between the two groups (37 of 169 in the bevel-down group and 25 of 169 in the bevel-up group). However, the incidence of posterior hematoma formation was lower in the bevel-down group (six of 169 vs. 17 of 169, p = .031). Additionally, there was less incidence of the posterior hematoma formation associated with puncture-on-withdrawal in the bevel-down group (six of 37 vs. 11 of 25, p = .034). Conclusions: The bevel-down approach of the right internal jugular vein may decrease the incidence of posterior venous wall damage and hematoma formation compared with the bevel-up approach, which implicates a reduced probability of carotid artery puncture with the bevel-down approach during internal jugular vein catheterization.

Uppermost blood levels of the right and left atria in the supine position : Implication for measuring central venous pressure and pulmonary artery wedge pressure

Background: To eliminate the influence of hydrostatic pressure, proper transducer positions for central venous pressure and pulmonary artery wedge pressure are at the uppermost blood levels of right atrium (RA) and left atrium (LA). This study was performed to investigate accurate reference levels of central venous pressure and pulmonary artery wedge pressure in the supine position. Methods: Chest computed tomography images of 96 patients without history of cardiothoracic surgery, heart disease, or cardiothoracic anatomical abnormality were retrospectively reviewed. The anteroposterior (AP) diameter of the thorax and the vertical distances from the skin on the back to the most anterior portion of RA (RA height) and LA (LA height) were measured. Their ratios were abbreviated, respectively, as RA height/AP diameter and LA height/AP diameter. Data are expressed as mean ± SD (range). Results: There was a significant difference [4.6 ± 1.0 (1.6–6.4) cm; P < 0.001] between RA and LA heights. AP diameter was positively correlated with RA and LA heights (R 2 = 0.839 and 0.700, respectively; P < 0.001). There was also a significant difference between RA height/AP diameter [0.83 ± 0.03 (0.71–0.91)] and LA height/AP diameter [0.62 ± 0.04 (0.52–0.72)] (P < 0.001). Conclusion: In the supine position, a central venous pressure transducer should be positioned approximately 4.6 cm higher than a pulmonary artery wedge pressure transducer. The external reference level for central venous pressure seems to be at approximately four fifths of the AP diameter of the thorax from the back, and that for pulmonary artery wedge pressure seems to be at approximately three fifths of the AP diameter.

A novel supraclavicular approach to the right subclavian vein based on three-dimensional computed tomography.

BACKGROUND: We used three-dimensional (3-D) computed tomography to develop a novel supraclavicular approach to the subclavian vein that minimizes the distance from insertion site to the vein. METHODS: Forty-five adult patients with normal body build were retrospectively included in the 3-D computed tomography investigation. Assuming that the clavisternomastoid angle was the skin entry point, and that the subclavian vein on the first rib was a target, the optimal angle of approach was measured on the simulated 3-D images. A 3-D video was developed from these images to explain the approach. In a pilot study, we prospectively tested this approach in 60 adult patients with normal body build requiring central venous catheterization. The number of attempts, success rate, and complications were noted. RESULTS: The optimal angle of approach was 10.6° ± 5.3° medially and 35.4° ± 12.5° posteriorly from the skin entry point. The estimated depth of the subclavian vein was 13.7 ± 3.1 mm. During the pilot study, the first trial with a finder needle was successful in 87% of patients and the overall success rate of catheterizations was 100% without complications. CONCLUSIONS: The proposed supraclavicular approach to the subclavian vein is a simple method of central venous catheterization. The pilot study suggests the method is reasonably safe. The video explaining the approach graphically is available in the supplementary material.

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

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.

Prediction of bispectral index during target-controlled infusion of propofol and remifentanil: A deep learning approach

Background: The discrepancy between predicted effect-site concentration and measured bispectral index is problematic during intravenous anesthesia with target-controlled infusion of propofol and remifentanil. We hypothesized that bispectral index during total intravenous anesthesia would be more accurately predicted by a deep learning approach. Methods: Long short-term memory and the feed-forward neural network were sequenced to simulate the pharmacokinetic and pharmacodynamic parts of an empirical model, respectively, to predict intraoperative bispectral index during combined use of propofol and remifentanil. Inputs of long short-term memory were infusion histories of propofol and remifentanil, which were retrieved from target-controlled infusion pumps for 1,800 s at 10-s intervals. Inputs of the feed-forward network were the outputs of long short-term memory and demographic data such as age, sex, weight, and height. The final output of the feed-forward network was the bispectral index. The performance of bispectral index prediction was compared between the deep learning model and previously reported response surface model. Results: The model hyperparameters comprised 8 memory cells in the long short-term memory layer and 16 nodes in the hidden layer of the feed-forward network. The model training and testing were performed with separate data sets of 131 and 100 cases. The concordance correlation coefficient (95% CI) were 0.561 (0.560 to 0.562) in the deep learning model, which was significantly larger than that in the response surface model (0.265 [0.263 to 0.266], P < 0.001). Conclusions: The deep learning model–predicted bispectral index during target-controlled infusion of propofol and remifentanil more accurately compared to the traditional model. The deep learning approach in anesthetic pharmacology seems promising because of its excellent performance and extensibility.

Reliability of Point-of-care Hematocrit Measurement During Liver Transplantation

BACKGROUND: Although point-of-care (POC) analyzers are commonly used during liver transplantation (LT), the accuracy of hematocrit measurement using a POC analyzer has not been evaluated. In this retrospective observational study, we aimed to evaluate the accuracy of hematocrit measurement using a POC analyzer and identify potential contributors to the measurement error and their influence on mistransfusion during LT. METHODS: We retrospectively collected 6461 pairs of simultaneous intraoperative hematocrit measurements using POC analyzers and laboratory devices during LTs in 901 patients. The agreement of hematocrit measurements was assessed using Bland-Altman analysis for repeated measurements, while the incidence and magnitude of hematocrit measurement error were compared among 16 different laboratory abnormality categories. A generalized estimating equation analysis was performed to identify potential contributors to falsely low-measured POC hematocrit. Additionally, we defined potential “overtransfusion” in the case when POC hematocrit was <20% and laboratory hematocrit was ≥20% and investigated its association with intraoperative transfusion. RESULTS: The POC hematocrit measurements were falsely lower than the laboratory hematocrit measurements in 70.3% (4541/6461) of pairs. The median (interquartile range) of hematocrit measurement error was −1.20 (−2.60 to 0.20). Bland-Altman analysis showed that 24.5% (1583/6461) of the errors were outside our a priori defined clinically acceptable limits of ±3%. The incidence of falsely low-measured hematocrit was significantly higher with the presence of concomitant hypoalbuminemia and hypoproteinemia. Hypoalbuminemia combined with hyperglycemia showed significantly larger hematocrit measurement error. Hypoalbuminemia, hypoproteinemia, and hyperglycemia were predictors of falsely low-measured hematocrit. Furthermore, the overtransfusion group showed larger amount of transfusion than the adequately transfused group, with a median difference of 2 units (95% confidence interval [0–4], P = .039), despite similar amount of blood loss. CONCLUSIONS: Hematocrit measured using the POC device tends to be lower than the laboratory hematocrit measured during LT. Commonly encountered laboratory abnormalities during LT include hypoalbuminemia, hypoproteinemia, and hyperglycemia, which may contribute to falsely low-measured POC hematocrit. Careful consideration of these confounders may help reduce overtransfusion that occurs due to falsely low-measured POC hematocrit.