Youn Yi Jo

The effect of pressure-controlled ventilation on pulmonary mechanics in the prone position during posterior lumbar spine surgery: a comparison with volume-controlled ventilation.

Background: When an anesthetized patient is turned to the prone position using the Wilson frame, dynamic compliance (Cdyn) decreases and peak airway pressure (Ppeak) increases. As pressure-controlled ventilation (PCV) decreases the Ppeak, this prospective, randomized study was designed to compare the effect of PCV and volume-controlled ventilation (VCV) on lung mechanics in the prone position using the Wilson frame during posterior lumbar spine surgery. Methods: Forty patients scheduled for posterior lumbar spine surgery were randomly allocated to receive mechanical ventilation using either the VCV (n=20) or PCV (n=20) mode. Respiratory variables (including Ppeak and Cdyn) and oxygenation parameters were recorded at the supine position (Tsupine) and 30 minutes after prone positioning (Tprone). Results: During the study period, tidal volume, minute volume, end-tidal carbon dioxide tension, and positive end-expiratory pressure were comparable between the 2 groups. The Ppeak in the PCV group was lower than that in the VCV group throughout the study period (P=0.007 and 0.003 at Tsupine and Tprone, respectively) and was increased at Tprone compared with Tsupine in both groups. Cdyn was decreased from Tsupine to Tprone in both groups. However, the Cdyn in the PCV group was higher than that in the VCV group during the study period. The arterial oxygen tension was comparable between the 2 groups during the study period. Conclusions: PCV provides lower Ppeak compared with VCV when the ventilator is set to deliver the same tidal volume and variable respiratory rate to maintain a constant end-tidal carbon dioxide tension in patients undergoing posterior lumbar spine surgery in the prone position using the Wilson frame.

Resolvin E1 Inhibits Substance P-Induced Potentiation of TRPV1 in Primary Sensory Neurons

The neuropeptide substance P (SP) is expressed in primary sensory neurons and is commonly regarded as a “pain” neurotransmitter. Upon peripheral inflammation, SP activates the neurokinin-1 (NK-1) receptor and potentiates activity of transient receptor potential vanilloid subtype 1 (TRPV1), which is coexpressed by nociceptive neurons. Therefore, SP functions as an important neurotransmitter involved in the hypersensitization of inflammatory pain. Resolvin E1 (RvE1), derived from omega-3 polyunsaturated fatty acids, inhibits TRPV1 activity via activation of the chemerin 23 receptor (ChemR23)—an RvE1 receptor located in dorsal root ganglion neurons—and therefore exerts an inhibitory effect on inflammatory pain. We demonstrate here that RvE1 regulates the SP-induced potentiation of TRPV1 via G-protein coupled receptor (GPCR) on peripheral nociceptive neurons. SP-induced potentiation of TRPV1 inhibited by RvE1 was blocked by the Gαi-coupled GPCR inhibitor pertussis toxin and the G-protein inhibitor GDPβ-S. These results indicate that a low concentration of RvE1 strongly inhibits the potentiation of TRPV1, induced by the SP-mediated activation of NK-1, via a GPCR signaling pathway activated by ChemR23 in nociceptive neurons. RvE1 might represent a new therapeutic target for the treatment of inflammatory pain as a prospective endogenous inhibitor that strongly inhibits TRPV1 activity associated with peripheral inflammation.

The predictors for continuous renal replacement therapy in liver transplant recipients.

BACKGROUND Acute renal failure (ARF) after liver transplantation requiring continuous renal replacement therapy (CRRT) adversely affects patient survival. We suggested that postoperative renal failure can be predicted if a clinically simple nomogram can be developed, thus selecting potential risk factors for preventive strategy. METHODS We retrospectively reviewed the medical records of 153 liver transplant recipients from January 2008 to December 2011 at Severance Hospital, Yonsei University Health System, in Seoul, Korea. There were 42 patients treated with CRRT (20 and 22 patients received transplants from living and deceased donors, respectively) and 115 were not. Univariate and stepwise logistic multivariate analyses were performed. A clinical nomogram to predict postoperative CRRT application was constructed and validated internally. RESULTS Hepatic encephalopathy (HEP; odds ratio OR, 5.47), deceased donor liver donations (OR, 3.47), Model for End-Stage Liver Disease (MELD) score (OR, 1.09), intraoperative blood loss (L; OR, 1.16), and tumor (hepatocellular carcinoma) as the indication for liver transplantation (OR, 0.11) were identified as independent predictive factors for postoperative CRRT on multivariate analysis. A clinical prediction model constructed for calculating the probability of CRRT post-transplantation was 1.7000 × HEP + [-4.5427 + 1.2440 × (deceased donor) + 0.0830 × (MELD score) + 0.000149 × the amount of intraoperative bleeding (L) - 2.1785 × tumor]. The validation set discriminated well with an area under the curve (AUC) of 0.90 (95% confidence interval, 0.85-0.95). The predicted and the actual probabilities were calibrated with the clinical nomogram. CONCLUSIONS We developed a predictive model of postoperative CRRT in liver transplantation patients. Perioperative strategies to modify these factors are needed.

The uncalibrated pulse contour cardiac output during off-pump coronary bypass surgery: performance in patients with a low cardiac output status and a reduced left ventricular function

Background We compared the continuous cardiac index measured by the FloTrac/Vigileo™ system (FCI) to that measured by a pulmonary artery catheter (CCI) with emphasis on the accuracy of the FCI in patients with a decreased left ventricular ejection fraction (LVEF) and a low cardiac output status during off-pump coronary bypass surgery (OPCAB). We also assessed the influence of several factors affecting the pulse contour, such as the mean arterial pressure (MAP), the systemic vascular resistance index (SVRI) and the use of norepinephrine. Methods Fifty patients who were undergoing OPCAB (30 patients with a LVEF ≥ 40%, 20 patients with a LVEF < 40%) were enrolled. The FCI and CCI were measured and we performed a Bland-Altman analysis. Subgroup analyses were done according to the LVEF (< 40%), the CCI (≤ 2.4 L/min/m), the MAP (60-80 mmHg), the SVRI (1,600-2,600 dyne/s/cm5/m2) and the use of norepinephrine. Results The FCI was reliable at all the time points of measurement with an overall bias and limit of agreement of -0.07 and 0.67 L/min/m2, respectively, resulting in a percentage error of 26.9%. The percentage errors in the patients with a decreased LVEF and in a low cardiac output status were 28.2% and 22.3%, respectively. However, the percentage error in the 91 data pairs outside the normal range of the SVRI was 40.2%. Conclusions The cardiac output measured by the FloTrac/Vigileo™ system was reliable even in patients with a decreased LVEF and in a low cardiac output status during OPCAB. Acceptable agreement was also noted during the period of heart displacement and grafting of the obtuse marginalis branch.

The effect of epidural administration of dexamethasone on postoperative pain: a randomized controlled study in radical subtotal gastrectomy

Background Epidurally administered dexamethasone may reduce the incidence and severity of postoperative pain. We investigated whether postoperative pain could be alleviated by preoperative or postoperative epidural dexamethasone administration in patients undergoing major abdominal surgery. Methods Ninety patients (age 30-77 with American Society of Anesthesiologists physical status I and II) undergoing radical subtotal gastrectomy were randomly allocated to three groups using computer generated randomization. In all groups, 10 ml of 0.25% ropivacaine was injected epidurally before the start and at the end of the operation. In Group I, a bolus ropivacaine epidural without dexamethasone was administered. In Group II, dexamethasone (5 mg) was added to the ropivacaine bolus epidural before the start of operation. In Group III, the same amount of dexamethasone was given with the ropivacaine epidural at the end of operation. Effort and resting VAS, the use of rescue analgesics and any complications noted during the procedure were evaluated. Results VAS and requirements of rescue analgesics were significantly lower in Groups II and III when compared to Group I. There were no difference in the incidence of nausea and vomiting between groups, but an itching sensation was frequent in Group III. Conclusions The administration of 5 mg of dexamethasone epidurallly, before or after operation, could reduce the pain and analgesic requirement after radical subtotal gastrectomy.

The effect of warmed inspired gases on body temperature during arthroscopic shoulder surgery under general anesthesia

Background Perioperative hypothermia can develop easily during shoulder arthroscopy, because cold irrigation can directly influence core body temperature. The authors investigated whether active warming and humidification of inspired gases reduces falls in core body temperature and allows redistribution of body heat in patients undergoing arthroscopic shoulder surgery under general anesthesia. Methods Patients scheduled for arthroscopic shoulder surgery were randomly assigned to receive either room temperature inspired gases using a conventional respiratory circuit (the control group, n = 20) or inspired gases humidified and heated using a humidified and electrically heated circuit (HHC) (the heated group, n = 20). Results Core temperatures were significantly lower in both groups from 30 min after anesthesia induction, but were significantly higher in the heated group than in the control group from 75 to 120 min after anesthesia induction. Conclusions In this study the use of a humidified and electrically heated circuit did not prevent core temperature falling during arthroscopic shoulder surgery, but it was found to decrease reductions in core temperature from 75 min after anesthesia induction.

Effects of high positive end‐expiratory pressure on haemodynamics and cerebral oxygenation during pneumoperitoneum in the Trendelenburg position

We investigated the effects of 10 cmH2O positive end‐expiratory pressure on cerebral haemodynamics and cerebral oxygenation in patients undergoing laparoscopic lower abdominal surgery in the 30° Trendelenburg position during desflurane anaesthesia. Twenty‐six patients were enrolled in this study. After anaesthesia induction, pneumoperitoneum was applied in Trendelenburg position. Twenty minutes later, positive end‐expiratory pressure was applied. There was no change in regional cerebral oxygen saturation (p = 0.376). Cerebral perfusion pressure decreased significantly over time (p < 0.001) and positive end‐expiratory pressure caused a further decrease in cerebral perfusion pressure (p = 0.036). The application of 10 cmH2O positive end‐expiratory pressure during pneumoperitoneum in the Trendelenburg position preserved regional cerebral oxygen saturation, but cerebral perfusion pressure decreased significantly due to its secondary haemodynamic effects.

Extrapyramidal side effects after metoclopramide administration in a post-anesthesia care unit -A case report-

Although the incidence of extrapyramidal reactions associated with metoclopramide has been reported to be approximately 0.2%, such reactions are rare in the anesthetic field. Several anesthetic adjuvants, including ondansetron and pregabalin, have also been associated with extrapyramidal side effect. Here, the authors report the case of a 47-year-old patient, previously administered pregabalin and ondansetron, who developed extrapyramidal side effects after a single injection of metoclopramide (10 mg) in a post-anesthesia care unit.

Comparative study of pressure- and volume-controlled ventilation on stroke volume variation as a predictor of fluid responsiveness in patients undergoing major abdominal surgery.

PURPOSE We hypothesized that the 2 ventilation modes might have a different influence on the stroke volume variation (SVV). This study investigated the effect of the ventilation modes on SVV as a predictor of fluid responsiveness during major abdominal surgery. MATERIALS AND METHODS Sixty patients were randomly allocated to volume-controlled ventilation (VCV, n = 30) or pressure-controlled ventilation (PCV, n = 30) modes. After the induction of anesthesia, hemodynamic variables and SVV were measured before and after volume expansion (VE) with colloid solution of 10 mL/kg. The ability of SVV to predict the fluid responsiveness was tested by calculation of the area under a receiver operating characteristic curve for an increase in stroke volume index of at least 15% after VE. RESULTS There were 10 and 16 responders in the VCV and PCV groups, respectively. The area under a receiver operating characteristic curve (95% confidence interval) for SVV before VE was 0.723 (0.538-0.907) and 0.799 (0.625-0.973) in the VCV and PCV groups, respectively. The optimal threshold value of SVV was 11% and 14% in the VCV and PCV groups, respectively. CONCLUSIONS Stroke volume variation can predict fluid responsiveness during both VCV and PCV modes. However, the optimal threshold values of SVV may differ according to the ventilation modes.

Extreme hyponatremia with moderate metabolic acidosis during hysteroscopic myomectomy -A case report-

Excess absorption of fluid distention media remains an unpredictable complication of operative hysteroscopy and may lead to lethal conditions. We report an extreme hyponatremia, caused by using an electrolyte-free 5 : 1 sorbitol/mannitol solution as distention/irrigation fluid for hysteroscopic myomectomy. A 34-year-old female developed severe pulmonary edema and extreme hyponatremia (83 mmol/L) during transcervical endoscopic myomectomy. A brain computed tomography showed mild brain swelling without pontine myelinolysis. The patient almost fully recovered in two days. Meticulous attention should be paid to intraoperative massive absorption of fluid distention media, even during a simple hysteroscopic procedure.