Wha Ja Kang

Effect of beach chair position on bispectral index values during arthroscopic shoulder surgery

Background Bispectral index (BIS) monitoring reduces the cases of intraoperative awareness. Several factors can alter BIS readings without affecting the depth of anesthesia. We conducted a study to assess the impact of beach chair position (sitting position) on BIS readings. Methods General anesthesia was administered to 30 patients undergoing arthroscopic shoulder surgery. Patients were kept in neutral position (supine) for 10 minutes and BIS readings, mean arterial blood pressure, heart rate, end-tidal carbon dioxide, and end-tidal sevoflurane were recorded. Patients were then shifted to beach chair position. After 15 minutes, data were recorded. Results A significant decrease in BIS values (P < 0.01) associated with a position change from neutral position to beach chair position was evident. Conclusions BIS values are significantly decreased in the beach chair position compared with the neutral position and might affect interpretation of the depth of anesthesia.

General anesthesia for a patient with multiple system atrophy.

Multiple system atrophy (MSA) is a rare, adult-onset neurodegenerative disease [1]. Two clinical features characterize MSA: motor features and autonomic dysfunction [2]. During anesthesia, regulation of cardiovascular instability is an important issue. We report a case of successful general anesthesia in a MSA patient. A 66-year-old man (170 cm, 40 kg) presented for a laparoscopic hemicolectomy. Recent intermittent hematochezia suggested rectal cancer. MSA was diagnosed at age 56, and rapid progression left him bedridden. His past medical history included diabetes and hypertension. Preoperatively, no abnormal finding was detected on a laboratory examination, chest X-ray, or electrocardiography. In operating room, routine monitoring devices for electrocardiography, pulse oximetry, and non-invasive blood pressure, and a noninvasive cardiac output monitor showing cardiac output, cardiac index (CI), and stroke volume variation (SVV) were set up. To address possible cardiovascular instability, arterial cannulation was performed before anesthesia. A central venous catheter has already been inserted through the subclavian vein. Initial bispectral index (BIS) was 87, blood pressure (BP) 150/60 mmHg, heart rate (HR) 75 beats/min, central venous pressure (CVP) 3 cmH2O, CI 2.4 L/min/m2, and SVV 10%. General anesthesia was induced with etomidate 0.4 mg/kg intravenously. With good mask ventilation, 40 mg of rocuronium was injected intravenously, and we tried laryngoscopic intubation. Because of poor mouth opening even after full relaxation with the rocuronium, moving the laryngoscope forward was impossible. So, we performed a bronchoscopic intubation. Anesthesia was maintained with sevoflurane 1.5-2 vol% and intravenous remifentanil 0.05 µg/kg/min in an O2-air mixture at a 1 : 1 ratio. The operation lasted about 4 h and anesthesia was maintained appropriately with BIS at 35-50. At 25 min after induction of anesthesia, the BP abruptly fell from 160/85 to 80/50 mmHg. This was managed successfully with rapid fluid administration and a phenylephrine bolus dose of 40 µg intravenously. HR hardly changed, from 82 to 90 beats/min. However, systolic blood pressure dropped again to 80 mmHg during awakening despite the irritating sensation of the endotracheal tube. Phenylephrine 20 µg raised the BP to 100/60 mmHg again with little change in HR, 70-75 beats/min (Fig. 1). Finally, gentle extubation was tried, and no respiratory event occurred. He was transferred to the surgical intensive care unit, and has been cardiovascularly stable since then. He was returned to the ward next day. Fig. 1 Hemodynamic changes during anesthesia. (A) Indicates the changes in blood pressure and heart rate. There is an abrupt decrease in blood pressure to 80/50 mmHg at 25 min after induction, but almost no change in the heart rate. Similarly, a sudden drop ... The annual occurrence of MSA among those over 50 is ~3 per 100,000 with no gender predilection [1,2,3]. Currently, no definite diagnostic criteria or therapies exist, beyond supportive care [2]. There are several considerations regarding anesthesia in MSA. First, the anesthesiologist should be concerned about sudden hypotension due to dysautonomia. Several authors have reported that regional anesthesia is better than general anesthesia in maintaining cardiovascular stability in MSA because of absence of procedures that may aggravate hypotension, such as positive-pressure ventilation, and the avoidance of anesthetics for maintenance [3]. Nevertheless, there is no evidence that regional anesthesia is necessarily the right answer in MSA patients. In contrast, Cohen [1] reported a successful case of general anesthesia after failure of epidural anesthesia, induction with thiopental and succinylcholine, and maintenance with N2O and methoxyflurane. Ketamine was reported as a successful anesthetic in a MSA patient without hypotension in 1983 [4], because ketamine causes central sympathetic stimulation primarily through parasympathetic inhibition. We decided on general anesthesia for several reasons: noncooperation, the possibility of procedural failure due to involuntary movements, and regional anesthesia not being suitable for laparoscopic surgery. The preoperative hemodynamic state of our patient was stable; however, realizing that MSA patients have a damaged sympathetic system, we decided to use etomidate with its minimal cardiovascular effects. We also used remifentanil, which has been reported to effectively suppress cardiovascular reactions and myoclonus after endotracheal intubation with etomidate [5]. Moreover, in MSA patients, bilateral vocal cord paralysis can be a life-threatening complication [1,2]. This adverse event can be aggravated during the induction or post-extubation period due to several stimuli, such as tracheal intubation under insufficient depth of anesthesia or unnecessary suction during extubation. If a preoperative evaluation is impossible, preventative measures should be used. Although no case has been reported of awake bronchoscopic intubation in MSA patients, it is worth considering in patients who are suspected to have difficult airways if the patients are cooperative. We also prepared an emergency cricothyroidotomy kit; the anesthesiologist should always be ready for an emergency tracheostomy situation. In conclusion, anesthesia in MSA remains a great challenge due to the many potential complications. Anesthesiologists should consider the condition of patients with MSA and carefully decide on the appropriate method of anesthesia for the type of operation.

Comparison of two topographical airway length measurements in adults

Background A correct estimate of the tracheal tube insertion depth can prevent complications, including endobronchial intubation and vocal cord trauma. We evaluated a new topographical method for endotracheal tube positioning relative to the carina, using a well-known prior topographical method for comparison. Methods One hundred adult (male 50, female 50) patients were studied. The comparison topographic length (in cm) was measured by adding the distance between the right mouth corner and the right mandibular angle to the distance between the right mandibular angle and the center of the sternal manubrium. The new endotracheal tube insertion depth (in cm) was determined by adding the distance between the right mouth corner and the vocal cords, measured with the endotracheal tube itself, to the distance between the thyroid prominence and the manubriosternal joint, and then subtracting 4 cm. After intubation, the endotracheal tube was positioned properly at the right mouth corner and the endotracheal tube tip was evaluated using a fiberoptic bronchoscope at the carina. Results The distances from the tip of the endotracheal tube to the carina were not significantly different between the methods in the same gender. However, our method allowed endotracheal tube tip placement between 3 cm and 5 cm, above the carina more frequently than the prior method in males. Conclusions The new topographical method can be used as a guide to positioning the endotracheal tubes.

Audiovisual stimulation with synchronized pulsed tones and flickering lights set at a delta frequency can induce a sedative effect.

The perioperative period is a source of significant fear and anxiety for patients. Therefore, anxiolytic and sedative drugs are administered routinely, before and during surgery [1]. However, a larger dose of sedatives can delay the recovery in the ambulatory setting and be associated with an increased risk for complications.

Effects of the tourniquet deflation on bispectral index during knee arthroscopic surgery under the general anesthesia

BACKGROUND Tourniquet deflation during lower extremity surgery affects the hemodynamics and metabolism of the patient, which can affect brain activity. This study examined the changes in brain activity during tourniquet deflation by measuring the bispectral index (BIS). METHODS The BIS was measured during surgery in forty patients who had received knee arthroscopic surgery under general anaesthesia. The BIS was measured 5 minutes before deflation (DB5) and 5 minutes after deflation (DA5). RESULTS The BIS at DB5 and DA5 was 50.2 +/- 9.9 and 44.4 +/- 10.4, respectively. The BIS of DA5 was significantly lower than that of DB5 (P < 0.05). CONCLUSIONS Tourniquet deflation during lower extremity surgery decreases the BIS associated with hemodynamic and metabolic changes. However, its clinical significance in neurologically critical patients, such as geriatric or neurologically disabled patients, remains to be clarified.

Effects of esomeprazole premedication on gastric pH during laparoscopic surgery

BACKGROUND The use of CO2 for pneumoperitoneum during laparoscopic surgery provokes a decrement in the gastric pH. Since the incidence rate of PONV increases after laparoscopic surgery, the possibility of lung aspiration of gastric juice with a low pH during a postanesthetic emergence may increase and this could be fatal for the patient. We conducted this study to determine the effects of esomeprazole premedication on inhibiting the decrement of the gastric pH during laparoscopic surgery. METHODS 40 adult patients with no underlying diseases were chosen and 20 patients each were grouped as C (the control group) and E (the esomeprazole group). In both group, 0.2 mg glycopyrrolate was given intramuscularly 30 minutes prior to the surgery. In group E, esomeprazole was given orally 2 hours prior to the surgery. The pH, PaCO2, and PETCO2 were measured via pH probe, an ABGA and an capnogram at preinsufflation and 15, 30 and 60 minutes after the CO2 insufflation and right before CO2 exhaustion (predeflation). RESULTS Comparing the measurements of the gastric pH between group E and group C, all the results showed a significant increase in group E (P < 0.05). The difference of the PaCO2 and PETCO2 in the two groups was not significance. CONCLUSIONS In contrast to the decrease in the gastric pH as the PaCO2 and PETCO2 increased in group C, the gastric pH in group E remained high until the end of the surgery despite the increase in the PaCO2 and PETCO2. Esomeprazole premedication seem to have an effect for inhibiting the gastric pH decrement regardless of the increase in the PaCO2 and PETCO2 during laparoscopic surgery.