Efficacy of arterial occlusion pressure estimation-based tourniquet pressure settings in upper limb surgery.

BACKGROUND: The use of a minimal individualized effective pneumatic tourniquet pressure is recommended to avoid pressure related complications in extremity surgery. The aim of this study was to investigate the efficacy of arterial occlusion pressure estimation-based tourniquet pressure settings in upper limb surgery. METHODS: Hundred and fifteen patients undergoing upper limb surgeries were enrolled in the present study. Arterial occlusion pressure estimation formula was used and a safety margin of 20 mmHg was added to arterial occlusion pressure in the tourniquet pressure setting. Primary and secondary endpoints were the amount of tourniquet pressure and its effectiveness respectively. Other outcome measures included the tourniquet pressure setting time and tourniquet related complications. Surgical team unaware of the tourniquet pressure assessed the bloodless surgical field. RESULTS: The mean initial and maximal tourniquet pressures were 171.5 ± 13.7 and 175.5 ± 13.2 mmHg, respectively. The effectiveness of the tourniquet was rated as "excellent" and "good" in the initial and middle stages, and at the end of the surgery of the procedure in 97.3%, 99.1%, and 100% of cases respectively. The mean tourniquet pressure setting time was 29.0 ± 3.7 s. No tourniquet related complications were observed. CONCLUSIONS: Arterial occlusion pressure estimation-based tourniquet pressure setting is a practical and effective method, which allows using lower tourniquet pressures than previously used in the literature for upper extremity surgery.

[Analysis of choroidal thickness in AP-ROP, threshold disease and ROP without laser photocoagulation]. / Untersuchung der Aderhautdicke bei aggressiver posteriorer Retinopathia praematurorum, Threshold Disease und Frühgeborenenretinopathie ohne Laserphotokoagulation.

BACKGROUND: Enhanced depth imaging (EDI) and spectral domain optical coherence tomography (SD-OCT) provide high-definition cross-sectional images of the choroid. Information on alterations in choroidal thickness (CT) after laser photocoagulation (LC) in aggressive posterior retinopathy of prematurity (APROP) and threshold disease (TD) is rare. PATIENTS AND METHODS: A total of 75 eyes were retrospectively analyzed in 4 groups. Groups 1 and 2 included patients with APROP and TD, respectively, who underwent LC. Group 3 included ROP children who did not undergo LC and group 4 included full-term children. Infants aged ≥4 < 7, who had examination of subfoveal (SF) CT with SD-EDI-OCT, visual acuity (VA), spherical equivalent (SE), anterior segment and fundus examination, axial lenght (AXL) were included. The results of SFCT, VA and SE at the age of ≥ 4 < 7 years, AXL, gestational age (GA), birth weight (BW) and age at examination were compared between the groups. Potential risk factors (GA, BW, SE, AXL and SFCT) influencing visual acuity were evaluated by using multivariate linear regression analysis. RESULTS: The results of SFCT and AXL were not significantly different between groups 2 and 3 or between groups 3 and 4. There was a significant difference between the other groups for SFCT and AXL and VA was significantly different between all groups. The SE was not significantly different between groups 3 and 4 but there was a significant difference for SE, BW and GA between the groups. Age at examination was not significantly different between the groups. Multivariate linear regression analysis revealed SFCT for groups 1 and 2, GA for group 3 and GA, SFCT and AXL for group 4 as independent risk factors influencing visual acuity. CONCLUSION: The regression model used for groups 1-4 explains the variation of the dependent risk factor LogMar VA for groups 1-4 with 31.2 %, 43.5 %, 9.6 % and 69.4 %, respectively. These values expressed in percentage demonstrate that even more predictors may influence the dependent factor LogMar VA than evaluated in the study.

Changes in difficult airway predictors following mandibular setback surgery.

The aim of this study was to determine the effect of surgical mandibular backward movements on the predictors of a difficult airway. Thirty-seven skeletal class III patients were included in this study. The Mallampati score, body mass index (BMI), maximal inter-incisal distance, and thyromental and sternomental distances of these patients were evaluated preoperatively and at 6 months and 2 years postoperatively. A sagittal split ramus osteotomy (SSRO) without genioplasty was performed in all patients by the same surgical team, and anaesthesia was provided by the same anaesthesiologist using nasotracheal intubation. The paired samples t-test and Wilcoxon signed-rank test were used for statistical comparisons of the data. There were no statistically significant changes in BMI or sternomental and thyromental distances after SSRO. The maximal inter-incisal distance was significantly reduced at 6 months postoperatively (P<0.05), but no statistical difference was found between the values obtained preoperatively and at 2 years postoperative. A statistically significant increase in Mallampati score was observed postoperatively (P<0.05). Both the patient and practitioner should be aware of the risks associated with an increased postoperative Mallampati score in mandibular setback patients. The amount of mandibular setback in skeletal class III patients with a high preoperative Mallampati score should be limited to prevent potential postoperative airway problems.

Thoracic epidural anesthesia and blood glucose levels in diabetic patients undergoing cardiopulmonary bypass under insulin infusion according to the Portland protocol.

BACKGROUND: We investigated the effect of thoracic epidural anesthesia on perioperative blood glucose levels in diabetic patients undergoing cardiopulmonary bypass by continuous insulin infusion according to the Portland Protocol. MATERIAL AND METHODS: Diabetic patients undergoing surgery with cardiopulmonary bypass were assigned to receive either general anesthesia alone (n=40) or general anesthesia with thoracic epidural anesthesia (n=18). Patient data were retrospectively reviewed from prospective chart records used in our anesthesia clinic. In all study patients, insulin infusion with the Portland Protocol was used to maintain stable blood glucose levels. We evaluated blood glucose levels in both groups at 6 time points including before surgery, before cardiopulmonary bypass, during cardiopulmonary bypass, immediately following cardiopulmonary bypass, and on the first and second postoperative days. The amounts of insulin required at the intraoperative period and during two postoperative days were compared between two groups. RESULTS: Groups were similar with respect to the duration of cardiopulmonary bypass, aortic cross-clamping, surgery, and blood glucose levels at any of the 6 time points, mean insulin requirements during intraoperative period and mean insulin requirements and blood glucose levels during the first 2 postoperative days (General anesthesia alone, 189+/-29 mg/dl vs. General anesthesia with thoracic epidural anesthesia, 191+/-19 mg/dl; p=0.782). CONCLUSIONS: In diabetic patients undergoing cardiopulmonary bypass receiving insulin infusion by the Portland Protocol for glycemic control, thoracic epidural anesthesia provides no additional benefit for maintaining blood glucose levels during surgery.

Propofol inhibits potassium chloride induced contractions of isolated human umbilical vessels.

BACKGROUND AND OBJECTIVE: We have evaluated the effects of propofol and its relationship with K+ channels on human isolated umbilical vessels. METHODS: Umbilical vessel rings were suspended in isolated organ baths containing Krebs-Ringer solution. In the first series of experiments the effect of propofol (10(-9)-10(-4) M) was examined in a concentration-dependent manner on umbilical vessels precontracted with KCl (60 mmol). In the second series, these effects were studied in the presence of tetraethylammonium. RESULTS: A mild contraction was produced by low dose propofol in both precontracted umbilical artery and umbilical vein segments. 10(-4) M propofol caused significant relaxation in both umbilical artery and umbilical vein. The relaxation response was significantly reduced by the addition of 10(-1) M tetraethylammonium. CONCLUSION: These results suggested that the responses of propofol on KCl-induced contractions of both umbilical artery and vein were dose dependent, and this effect involved Ca2+ activated K+ channels.

Which is responsible for the haemodynamic response due to laryngoscopy and endotracheal intubation? Catecholamines, vasopressin or angiotensin?

BACKGROUND AND OBJECTIVE: We have investigated the concentrations of epinephrine, norepinephrine, vasopressin and angiotensin converting enzyme activity to explore the role of these mediators in the neuroendocrine response to laryngoscopy and tracheal intubation. METHODS: One hundred (50 male, 50 female) ASA I patients aged 20-50 yr (mean+/-SEM; 35.59+/-0.99) were included in the study. They were undergoing elective surgery under standard anaesthesia induction and maintenance using tracheal intubation. Plasma concentrations of epinephrine, norepinephrine and vasopressin as well as plasma angiotensin converting enzyme activity were determined at four time points, before (T1) and after (T2) induction, and 2 (T3) and 5 min (T4) after intubation. Blood pressure and heart rate were recorded at corresponding times to reveal if any correlation existed between haemodynamic parameters and neuroendocrine response. RESULTS: Heart rate increased after induction and intubation (P<0.05) and decreased significantly at T4 (P<0.05). Systolic blood pressure decreased significantly (P<0.05) after induction and increased slightly after intubation decreasing to below baseline value (P<0.05) at T4. Diastolic blood pressure increased slightly after intubation and decreased significantly (P<0.05) at T4. Plasma epinephrine and norepinephrine concentrations decreased after induction and increased at T3 and T4 without reaching significance. Vasopressin concentrations increased slightly at T2 and T3 and decreased significantly at T4 (P<0.05). Angiotensin converting enzyme activity was unaffected when compared with baseline values. CONCLUSIONS: Blood pressure, heart rate, plasma epinephrine, norepinephrine and vasopressin concentrations increased slightly in response to laryngoscopy and intubation, all returning to or below baseline 5 min later with no change in angiotensin converting enzyme activity in normotensive patients.

Syringe pumps take too long to give occlusion alarm.

BACKGROUND: The aim of this study was to assess the time needed to trigger an occlusion alarm, and the influence of the type of infusion pump, type and size of the syringe, and the set infusion rate. METHODS: Forty syringe pumps (20 JMS SP-100 and 20 JMS SP-500 machines) were tested using two types (JMS and Hayat) and two sizes (20 and 50 ml) of syringes at four infusion rates (0.5, 1, 2 and 5 ml x h(-1)). Syringes filled with saline were occluded with a stopcock, and times to activation of the occlusion alarm were recorded. Statistical analysis was performed with Wilcoxon and Mann-Whitney U-tests, P < 0.05 was considered significant. RESULTS: The mean time to alarm activation was longer with lower infusion rates and larger syringes (P < 0.05). We recorded delays up to 117.3 +/- 9.4 min with 50 ml syringe at 0.5 ml x h(-1) and 15.0 +/- 7.1 min at 5 ml x h(-1). Syringe type had no effect on time to alarm activation (P > 0.05). The alarm on the JMS SP-500 pump was activated faster than the JMS SP-100 pump (P < 0.05). CONCLUSION: Our results showed that activation of occlusion alarms on both pumps takes a considerable time, and that the mean time to alarm activation was longer with low infusion rates and larger syringes. To reduce occlusion alarm delays smaller sized syringes with low compliance should be used and staff be alerted when using low flow rates with highly concentrated potent drugs.

Dealing with a hemophilia-A patient undergoing cerebral aneurysm surgery.

In this article anesthesiologic and hematologic aspects of a patient with Hemophilia-A, who underwent craniotomy for a right middle cerebral artery aneurysm, are discussed.

Chronic subdural haematoma following caesarean section under spinal anaesthesia.

Intracranial subdural haematoma is a rare complication of spinal anaesthesia. This report describes the case of a 31-year-old woman who presented with post partum headache following spinal anaesthesia for caesarean section. Bilateral haematomata were evacuated via burr-holes performed under total intravenous anaesthesia and the patient made a complete and uneventful recovery. The recognized causes of subdural haematoma are discussed.