Jae-Hyon Bahk

A comparison of retrobulbar block, sub-Tenon block, and topical anesthesia during cataract surgery

Purpose This randomized, double-blinded, prospective study was performed to compare the intraoperative hemodynamic variables and the patient-reported outcomes, such as intra- and postoperative analgesia and patient satisfaction, of retrobulbar block, sub-Tenon block, and topical anesthesia during cataract surgery under monitored anesthesia care. Methods Eighty-one patients, ASA physical status I–III, undergoing elective cataract surgery under monitored anesthesia care, aged between 43 and 78 years, were randomly assigned to three groups: retrobulbar block (group R), sub-Tenon block (group S), or topical anesthesia (group T). Three minutes after the start of monitored anesthesia care with lidocaine-propofol-remifentanil mixture, an ophthalmologist performed regional anesthesia. Intraoperative hemodynamics, pain score, and patients satisfaction with the anesthetic experiences were recorded by a study-blinded anesthesiologist. Results Mean arterial pressure and heart rate in group R were significantly higher than those in groups S and T during and just after the regional block (p<0.05). Group R required smaller dosage of patient controlled sedation and fewer supplemental bolus doses than groups S and T (p<0.05). On the other hand, group S showed the highest satisfaction scores among the three groups (p<0.05). Conclusions Sub-Tenon block seems to be better than retrobulbar block and topical anesthesia in patient satisfaction though adequate analgesia was achieved after retrobulbar block during cataract surgery under monitored anesthesia care.

Computed tomographic study of lumbar (L3–4) epidural depth and its relationship to physical measurements in young adult men

Background and Objectives. This study was performed to devise a method for predicting epidural depth more accurately with a variety of physical measurements not previously studied. Methods. Computed tomography was used to accurately measure the L3‐4 epidural depth. The inclusion criteria were restricted to healthy men, 20‐25 years of age, in order to rule out the influences of age and sex. Results. Significant correlations with depth from skin to the center of the “triangular” posterior epidural space (Sk‐Ep) were found for waist circumference, waist circumference/height ratio, body mass index (BMI), weight/height ratio, weight/neck circumference ratio, and weight. The depth from the supraspinous ligament to the center of the posterior epidural space (Sl‐Ep) did not correlate with any physical measurements. However, Sk‐Sl, which equals Sk‐Ep minus Sl‐Ep (ie, the depth from the skin to the supraspinous ligament) correlated with waist circumference/height ratio, waist circumference, BMI, and weight/height ratio. Conclusion. Addition of the physical parameters such as waist circumference/neck circumference ratio or BMI results in a higher predictive value for epidural depth than use of more traditional physical parameters such as weight/height ratio and/or weight only. The value of Sl‐Ep is independent of any physical parameters. Thus, the significant correlation between the physical measurements and the epidural depth seems to be due only to obesity‐related factors.

The diabetes-induced functional and distributional changes of the alpha 1-adrenoceptor of the abdominal aorta and distal mesenteric artery from streptozotocin-induced diabetic rats

Background The aim of this study was to evaluate the effect of diabetes on the function and distribution of vascular α1-adrenoceptors in the abdominal aorta and distal mesenteric artery from streptozotocin (STZ)-induced diabetic rats at the level of the α1-adrenoceptor subtypes. Methods Diabetes was induced by a single intravenous injection of STZ (60 mg/kg) in 8 week-old male Sprague-Dawley rats (n = 11). Age-matched normal rats (n = 14) were used as a control group. Four weeks after STZ injection, the tilting-induced change of the mean arterial pressure was recorded. The α1-adrenoceptor subtypes mediating the contractions of the distal mesenteric artery and abdominal aorta were investigated using the agonist phenylephrine and subtype-selective antagonists that included prazocin, 5-methylurapidil and BMY 7378. The expressions of the α1-adrenoceptor subtypes of each artery were examined by immunofluorescence staining using the subtype selective antibodies. Results The recovery of the mean arterial pressure was delayed after positional change in the diabetic rats. Compared with that of the normal rats, the contractile response to phenylephrine was increased in the abdominal aortas and it was decreased in the distal mesenteric arteries in the diabetic rats. In addition, compared with the normal rats, the fluorescent intensity of all the α1-adrenoceptor subtypes was increased in the abdominal aortas and it was decreased in the mesenteric arteries of the diabetic rats. Conclusions Diabetes increased the contractility of the abdominal aorta in response to phenylephrine, yet diabetes decreased that of the mesenteric arteries in the STZ-induced diabetic rats. Those results are mainly based on the overall change of the α1-adrenoceptor, and not on the change of the specific α1-adrenoceptor subtypes.

Photoplethysmogram change by Trendelenburg position and insufflation of abdominal carbon dioxide

To the Editor: Laparoscopic surgery has an inherent risk of complications because of increased abdominal pressure (IAP) and intra-abdominal carbon dioxide inflation [1]. We report a case where venous pulsation was detected in finger photoplethysmogram (PPG) during laparoscopic surgery in the head-down position (HDP). A 32-year-old woman (height 160 cm, weight 64 kg) was scheduled for laparoscopic right ovarian cystectomy. Preoperatively, she had no significant medical history except for a previous caesarian section. Before induction of anesthesia, the blood pressure was 125/74 mmHg and the heart rate was 90/min. The patient’s status was monitored by routine protocols. The PPG probe (DS 100A; Nellcor, Pleasanton, CA) was placed on the right index finger and connected to a patient monitor (Solar 8000M; GE Medical System, Milwaukee, WI). PPG data were stored via a 12-bit analog-digital converter (EZAD-512; ELBIO, Seoul, Korea) at a rate of 100 Hz. After induction of anesthesia, the patient was placed in the lithotomy position with the right arm abducted at 90 and the left arm attached to the side of body. Initial PPG was normal (Fig. 1a) and pulse oximetry values (SpO2) were 99 %. After carbon dioxide was insufflated at a pressure of 12 cmH2O, the operating table was tilted to 30 in the HDP. The SpO2 was 95 % and the waveform of PPG showed unexpected peaks and high amplitude (Fig. 1b). Arterial blood pressure changes were within 20 mmHg during the position change. When the PPG probe was moved to the patient’s other finger, the same SpO2 and PPG were observed. However, when the PPG probe was placed on a finger of one of the authors, normal PPG was obtained, thereby confirming that the PPG probe was functioning well. A tourniquet (tourniquet 4500; VBM, Sulz, Germany) was applied to the right upper arm at a pressure of 20, 30, 40, and 50 mmHg to confirm the venous origin of the abnormal waveform (Fig. 1c) [2], with subsequent increase in the SpO2 to 97 %. The amplitude of abnormal peaks in PPG was slightly reduced when abdominal CO2 was deflated in the HDP, but its waveform was still different from that of normal PPG (SpO2 96 %). Normal SpO2 (99 %) and PPG similar to that in Fig. 1a were displayed when the patient was placed in the supine position without tourniquet application. It is possible that the pressure of the tourniquet could block the venous effect resulted from mild tricuspid regurgitation (around 20 mmHg), HDP (around 20 mmHg), and IAP (12 mmHg). The implication of this case report is that venous pulsation in PPG could be induced by IAP and HDP. The possible mechanism is that mild tricuspid regurgitation aggravated by HDP may cause a high degree of variability in the PPG. In this case, HDP significantly contributed to the formation of venous pulsation in PPG; however, IAP J.-H. Bahk W. Ahn (&) Department of Anesthesiology and Pain Medicine, Seoul National University Dental Hospital, 103 Daehangno Jongno-gu, Seoul 110-768, Republic of Korea e-mail: aws@snu.ac.kr

Perioperative cerebral infarct during cardiac surgery and changes in jugular venous O2 saturation and cerebral oximetry using near-infrared spectroscopy − A case report −

Despite reductions in surgical mortality, neurologic sequelae remain a devastating complication after cardiac surgery with cardiopulmonary bypass. Neurologic complications may be induced by a massive air embolism during cardiopulmonary bypass, even with extensive monitoring. This report describes a patient who had a fatal cerebral infarct during aortic valve and ascending aorta replacement surgery. We monitored jugular venous O2 saturation (SjvO2) and cerebral oximetry using near-infrared spectroscopy in the perioperative period. The operation and anesthesia were uneventful until the deep hypothermic total arrest for the replacement of the ascending aorta. However, restarting the cardiopulmonary bypass after deep hypothermic total arrest produced a brief (less than 10 seconds) but large amount of air in the root cannula. At this time, although cerebral oximetry did not show any changes, the SjvO2 decreased to 21% for about 3 minutes and then normalized. At 8 hours after surgery, the patient showed seizures and severe edema in both cerebral hemispheres on the MRI. The patient died 21 days after surgery.