Changes in the corrected carotid flow time can predict spinal anesthesia-induced hypotension in patients undergoing cesarean delivery: an observational study.

PURPOSE: Spinal anesthesia is a standard technique for cesarean delivery; however, it possesses a risk of hypotension. We hypothesised that the changes in the corrected flow time induced by the Trendelenburg position could predict the incidence of hypotension after spinal anesthesia for cesarean delivery. METHODS: Patients undergoing elective cesarean delivery under spinal anesthesia were enrolled. Before anesthesia induction, corrected flow time was measured in the supine and Trendelenburg positions (FTc-1 and FTc-2, respectively). Additionally, a percent change in corrected flow time induced by the Trendelenburg position was defined as ΔFTc. The primary endpoint was to investigate the ability of ΔFTc to predict the incidence of spinal anesthesia-induced hypotension until delivery. The receiver operating characteristics curves to assess the ability of FTc-1, FTc-2, and ΔFTc to predict the incidence of hypotension were generated. RESULTS: Finally, 40 patients were included, and of those, 26 (65%) developed spinal anesthesia-induced hypotension. The areas under the curve for FTc-1, FTc-2, and ΔFTc were 0.591 (95% CI: 0.424 to 0.743) (P = 0.380), 0.742 (95% CI: 0.579 to 0.867) (P = 0.004), and 0.882 (95% CI: 0.740 to 0.962) (P < 0.001) respectively, indicating ΔFTc as the best predictor among these three parameters. The best threshold for ΔFTc was 6.4% (sensitivity: 80.8% (95% CI: 53.8 to 96.2), specificity: 85.7% (95% CI: 42.9 to 100.0)). CONCLUSIONS: This study demonstrated that changes in the corrected carotid flow time induced by the Trendelenburg position could serve as a good predictor of spinal anesthesia-induced hypotension for cesarean delivery.

Tizanidine Induced Hypotension: Report of a Case and Review of the Literature.

INTRODUCTION: Spasticity is a common sequelae of stroke, and often these patients receive anti-spastic drugs such as baclofen or tizanidine. Stroke patients have multiple co-morbidities such as hypertension, diabetes, and seizure. Tizanidine is an α2 and imidazole receptor agonist at a spinal and supraspinal level resulting in reduced central sympathetic outflow and causing hypotension rarely, especially in those receiving beta-blockers or angiotensin-converting enzyme inhibitors. CASE PRESENTATION: We report a 56-year-old hypertensive male presenting with altered sensorium who had recurrent intracerebral hemorrhage with left spastic hemiplegia and focal seizures. He was on amlodipine, atenolol, telmisartan and oxcarbazepine. After 3 doses of tizanidine 2mg, his blood pressure dropped from 140/90 to 80/40 mmHg and pulse from 82 bpm to 44 bpm. His blood counts, serum chemistry, procalcitonin, and Trop I were normal. ECG revealed sinus bradycardia. After 8 hours of withdrawing tizanidine, his blood pressure became 110/70 mmHg, and on the next day, it became 140/82 mmHg. His attendants were taught physiotherapy to minimize spasticity. CONCLUSION: This patient highlights the need for close monitoring of patients receiving tizanidine co-medication with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. These drugs have a synergistic effect on reducing the renin-angiotensin-aldosterone system, thereby hypotension and bradycardia.

Controlled hypotension technology can improve patient recovery in the early postoperative period after total knee arthroplasty: A prospective, randomized controlled clinical study.

OBJECTIVES: The study aimed to analyze the application of controlled hypotension and tourniquets in total knee arthroplasty (TKA) to evaluate their early postoperative period effects in TKA. PATIENTS AND METHODS: A total of 183 patients (43 males, 140 females; mean age: 67.8±6.4 years; range, 50 to 84 years) with knee osteoarthritis who needed TKA were recruited for this prospective, randomized controlled clinical study between August 2022 and May 2023. The study included a tourniquet group (group T, 94 patients) and a controlled hypotension group (group H, 89 patients). In group T, an inflatable tourniquet was used throughout the operation, with the pressure of the tourniquet set at 300 mmHg. In group H, controlled hypotension was used, with the mean arterial pressure controlled at 55-65 mmHg. The outcome measures of this study included blood loss, coagulation function, inflammatory mediators, knee joint function, permeation thickness of bone cement around the tibial prosthesis, and cognitive function. RESULTS: The baseline demographics and clinical characteristics of the two groups of patients were comparable (p>0.05). Intraoperative blood loss in group H was higher than that in group T (p<0.05), whereas hemoglobin decrease, postoperative drainage flow, hidden blood loss, and total blood loss in group T were higher than in group H (p<0.05). Fibrinogen, D-dimer, C-reactive protein, and interleukin-6 levels were higher in group T than in group H on the first and third postoperative days (p<0.05). The knee joint function of group H was significantly better than that of group T on the fifth day and one month after the operation (p<0.05). There was no significant difference in the penetration thickness of bone cement around the tibial prosthesis between the two groups (p>0.05). There was no significant difference in Mini-Mental State Examination scores between the two groups on the same day (p>0.05). CONCLUSION: Controlled hypotension technology in TKA can reduce total blood loss by reducing hidden blood loss and can help to alleviate the postoperative hypercoagulable state, relieve inflammatory reactions, and facilitate early recovery of knee joint function after surgery.

Micro- and macrocirculatory effects of norepinephrine on anaesthesia-induced hypotension: a prospective preliminary study.

BACKGROUND: Intraoperative arterial hypotension (IOH) leads to increased postoperative morbidity. Norepinephrine is often use to treat IOH. The question regarding the mode of administration in either a bolus or continuous infusion remains unanswered. The aim of the present study was to describe and compare the effects on macrocirculation and microcirculation of a bolus and a continuous infusion of norepinephrine to treat IOH. METHODS: We conducted a prospective observational study with adult patients who underwent neurosurgery. Patients with invasive arterial blood pressure and cardiac output (CO) monitoring were screened for inclusion. All patients underwent microcirculation monitoring by video-capillaroscopy, laser doppler, near-infrared spectroscopy technology, and tissular CO2. In case of IOH, the patient could receive either a bolus of 10 µg or a continuous infusion of 200 µg/h of norepinephrine. Time analysis for comparison between bolus and continuous infusion were at peak of MAP. The primary outcome was MFI by videocapillaroscopy. RESULTS: Thirty-five patients were included, with 41 boluses and 33 continuous infusion. Bolus and continuous infusion induced an maximal increase in mean arterial pressure of +30[20-45] and +23[12-34] %, respectively (P=0,07). For macrocirculatory parameters, continuous infusion was associated with a smaller decrease in CO and stroke volume (p<0.05). For microcirculatory parameters, microvascular flow index (-0,1 vs. + 0,3, p=0,03), perfusion index (-12 vs. +12%, p=0,008), total vessel density (-0,2 vs. +2,3 mm2/mm2, p=0,002), showed significant opposite variations with bolus and continuous infusion, respectively. CONCLUSIONS: These results on macro and microcirculation enlighten the potential benefits of a continuous infusion of norepinephrine rather than a bolus to treat anaesthesia-induced hypotension. TRIAL REGISTRATION: (NOR-PHARM: 1-17-42 Clinical Trials: NCT03454204), 05/03/2018.

Can subclavian/infraclavicular axillary vein collapsibility index predict spinal anesthesia-induced hypotension in cesarean-section operations?

OBJECTIVE: Spinal anesthesia-induced hypotension (SAIH) is relatively common in pregnant women and has serious maternal and fetal side effects. In patients who are hypovolemic during spinal anesthesia, there may be a significant decrease in blood pressure caused by the decrease in preload. Subclavian vein sonography is a useful method for evaluating preoperative intravascular volume status. This study aimed to evaluate the efficacy of the pre-operative subclavian vein or infraclavicular axillary vein (SCV-AV) collapsibility index for predicting SAIH in cesarean-section (C-section). PATIENTS AND METHODS: In this prospective observational study, 82 women undergoing elective C-sections were recruited. Sonographic evaluation of SCV-AV was assessed before spinal anesthesia. After spinal anesthesia, changes in blood pressure were noted. The main outcome was the association between the SCV-AV measurements (diameter and collapsibility index) and SAIH. RESULTS: Hypotension developed in 53 (64%) patients after spinal anesthesia. The collapsibility index of the SCV-AV during spontaneous breathing and deep inspirium was not a significant predictor of a decrease in mean blood pressure (MBP) after spinal anesthesia (p<0.979, p<0.380). CONCLUSIONS: It was found that the SCV-AV collapsibility index is not a predictor of SAIH in pregnant women undergoing elective C-sections.

Association of infraclavicular axillary vein diameter and collapsibility index with general anesthesia-induced hypotension in elderly patients undergoing gastrointestinal surgery: an observational study.

BACKGROUND: The collapse index of inferior Vena Cava (IVC) and its diameter are important predictive tools for fluid responsiveness in patients, especially critically ones. The collapsibility of infraclavicular axillary vein (AXV) can be used as an alternative to the collapsibility of IVC (IVC-CI) to assess the patient's blood volume. METHODS: A total of 188 elderly patients aged between 65 and 85 years were recruited for gastrointestinal surgery under general anesthesia. Ultrasound measurements AXV and IVC were performed before induction of general anesthesia. Patients were grouped in accordance to the hypotension after induction. ROC curves were used to analyze the predictive value of ultrasound measurements of AXV and IVC for hypotension after induction of anesthesia. Pearson linear correlation was used to assess the correlation of ultrasound measurements and decrease in mean arterial blood pressure (MAP). RESULTS: The maximum diameter of AXV(dAXVmax) and the maximum diameter of IVC (dIVCmax) were not related to the percentage decrease in MAP; the collapsibility of AXV (AXV-CI) and IVC-CI were positively correlated with MAP changes (correlation coefficients:0.475, 0.577, respectively, p < 0.001). The areas under the curve (AUC) was 0.824 (0.759-0.889) for AXV-CI, and 0.874 (0.820-0.928) for IVC-CI. The optimal threshold for AXV-CI was 31.25% (sensitivity 71.7%, specificity 90.1%), while for IVC-CI was 36.60% (sensitivity 85.9%, specificity 79.0%). Hypotension and down-regulation of MAP during induction can be accurately predicted by AXV-Cl after correction for confounding variables. CONCLUSION: Infraclavicular axillary vein diameter has no significant correlation with postanesthesia hypotension, whereas AXV-CI may predict postanesthesia hypotension during gastrointestinal surgery of the elderly. TRIAL REGISTRATION: This study was registered in the Clinical Trial Registry of China on 05/06/2022 (ChiCTR2200060596).

Sevoflurane-induced hypotension causes cognitive dysfunction and hippocampal inflammation in mice.

Sevoflurane commonly adopted for anesthetic in clinical practice, however, its influences on cerebral blood flow and cognitive function remain controversial. Herein, the sevoflurane-induced hypotension on arterial blood pressure, cerebral blood flow, cognitive function, and hippocampal inflammation was investigated in mice. A significant decrease in arterial blood pressure and cerebral blood flow was indicated by the sevoflurane anesthesia treatment. Moreover, sevoflurane-induced hypotension was associated with the impaired cognitive function and the increased levels of NLRP3 inflammasome activation and oxidative stress in hippocampus. These findings suggest that sevoflurane-induced hypotension may lead to the cognitive dysfunction and hippocampal inflammation.

Pleth variability index during preoxygenation could predict anesthesia-induced hypotension: A prospective, observational study.

STUDY OBJECTIVE: To determine whether changes in the pleth variability index (PVi) during preoxygenation with forced ventilation for 1 min could predict anesthesia-induced hypotension. DESIGN: Prospective, observational study. SETTING: A tertiary teaching hospital. PATIENTS: Ninety-six patients who underwent general anesthesia using total intravenous anesthesia were enrolled. INTERVENTIONS: Upon the patient's arrival at the preoperative waiting area, a PVi sensor was affixed to their fourth fingertip. For preoxygenation, forced ventilation of 8 breaths/min in a 1:2 inspiratory-expiratory ratio was conducted using the guidance of an audio file. One minute after preoxygenation, anesthetic administration was initiated. Blood pressure was measured for the next 15 min. MEASUREMENTS: We calculated the difference (dPVi) and percentage of change (%PVi) between the PVi values immediately before and after forced ventilation. Anesthesia-induced hypotension was defined as a mean arterial pressure of <60 mmHg within 15 min after the infusion of anesthetics. MAIN RESULTS: Overall, 87 patients were included in the final analysis. Anesthesia-induced hypotension occurred in 31 (35.6%) of the 87 patients. Receiver operating characteristic curve analyses identified a cut-off value of -2 for dPVi, with an area under the curve of 0.691 (95% confidence interval [CI], 0.564-0.818; P < 0.001) and a cut-off value of -7.6% for %PVi, with an area under the curve of 0.711 (95% CI, 0.589-0.832; P < 0.001). Further, multivariate logistic regression analysis showed that a low %PVi with an odds ratio of 9.856 (95% CI, 3.131-31.032; P < 0.001) was a significant determinant of anesthesia-induced hypotension. CONCLUSIONS: Hypotension frequently occurs during general anesthesia induction and can impact outcomes. Additionally, the percentage change in the PVi before and after preoxygenation using deep breathing can be used to predict anesthesia-induced hypotension.

Effects of smoking on controlled hypotension with nitroglycerin during ear-nose-throat surgery.

Background and Aim: In this study, the aim was to research the effects of smoking habits on controlled hypotension administered with nitroglycerin during ear-nose-throat surgery. Materials and Methods: This study administered controlled hypotension with nitroglycerin and total intravenous anesthesia to a total of 80 patients undergoing septoplasty operations. The patients were divided into two groups of 40 non-smokers (Group 1) and 40 smokers (Group 2). Intravenous propofol infusion was used for anesthesia maintenance. Nitroglycerin with 0.25-1 µg/kg/min dose was titrated to provide controlled hypotension. During this process, the hemodynamic parameters of patients, total propofol and nitroglycerin amounts used, operation duration, and duration of controlled hypotension were recorded at the end of the operation. At the end of the operation, the surgeon assessed the lack of blood in the surgical field with Fromme Scale. Results: Fromme scale values were significantly higher in Group 2 compared to Group 1. The MAP values at 10, 20, 30 min, and end of operation were lower, while 10- and 20-min heart rate values were higher in Group 2 compared to Group 1. Conclusion: Nitroglycerin, chosen for controlled hypotension to reduce hemorrhage in the surgical field during nasal surgery, was shown to cause more pronounced hypotension and reflex tachycardia due to endothelial dysfunction linked to nicotine in patients who smoke. Despite lower pressure values in the smoking group, the negative effects of nicotine on platelet functions combined with similar effects of nitroglycerin to increase bleeding amounts.

Efficacy of Isoflurane-Remifentanil versus Propofol-Remifentanil on Controlled Hypotension and Surgeon Satisfaction in Rhinoplasty: A Single-Blind Clinical Trial Study.

Background: Rhinoplasty is a complex but popular surgery in Iran. The main complications of the surgery are post-operative bleeding and nasal septal hematoma due to poor intra-operative controlled hypertension. This study aimed to compare the efficacy of isoflurane-remifentanil (I-R) versus propofol-remifentanil (P-R) to induce controlled hypotension and to assess surgeon satisfaction with each of these combinations during rhinoplasty. Methods: In 2020-2021, a single-blind clinical study was conducted on 98 patients aged 18-50 years undergoing rhinoplasty at Mother and Child Hospital (Shiraz, Iran). Patients were randomly divided into P-R (n=48) and I-R (n=50) groups. Changes in systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and heart rate (HR) were assessed during surgery and in the recovery room. A questionnaire was used to evaluate the level of surgeon satisfaction. Data were analyzed using independent samples t test, Chi-square test, and repeated measures ANOVA with SPSS software. P<0.05 was considered statistically significant. Results: Five minutes after anesthesia induction, the P-R combination had a greater effect on reducing SBP (P=0.010), DBP (P=0.007), MAP (P=0.003), and HR (P=0.026) than I-R. However, from the 40th minute to the end of surgery and after 30 minutes of recovery, the I-R combination had a slightly better effect on blood pressure reduction than P-R. There was no difference in surgeon satisfaction with either of the two drug combinations. Conclusion: Both P-R and I-R combinations are recommended to induce hypotension during rhinoplasty. However, I-R is more effective than P-R in inducing the desired controlled hypotension.

Exploring the predictive value of combined ultrasound parameters for spinal anesthesia-induced hypotension in cesarean section: a prospective observational study.

BACKGROUND: Prophylactic vasopressor infusion can effectively assist with fluid loading to prevent spinal anesthesia-induced hypotension. However, the ideal dose varies widely among individuals. We hypothesized that hypotension-susceptible patients requiring cesarean section (C-section) could be identified using combined ultrasound parameters to enable differentiated prophylactic medical interventions. METHODS: This prospective observational trial was carried out within a regional center hospital for women and children in Sichuan Province, China. Singleton pregnant women undergoing combined spinal-epidural anesthesia for elective C-sections were eligible. Women with contraindications to spinal anesthesia or medical comorbidities were excluded. Velocity time integral (VTI) and left ventricular end-diastolic area (LVEDA) in the supine and left lateral positions were measured on ultrasound before anesthesia. Stroke volume, cardiac output, and the percentage change (%) in each parameter between two positions were calculated. Vital signs and demographic data were recorded. Spinal anesthesia-induced hypotension was defined as a mean arterial pressure decrease of > 20% from baseline. The area under the receiver operating characteristic curve (AUROC) was used to analyze the associations of ultrasound measurements, vital signs, and demographic characteristics with spinal anesthesia-induced hypotension. This exploratory study did not have a predefined outcome; however, various parameter combinations were compared using the AUROC to determine which combined parameters had better predictive values. RESULTS: Patients were divided into the normotension (n = 31) and hypotension groups (n = 57). A combination of heart rate (HR), LVEDAs, and VTI% was significantly better at predicting hypotension than was HR (AUROC 0.827 vs. 0.707, P = 0.020) or LVEDAs (AUROC 0.827 vs. 0.711, P = 0.039) alone, but not significantly better than VTI% alone (AUROC 0.827 vs. 0.766, P = 0.098). CONCLUSION: The combined parameters of HR and LVEDAs with VTI% may predict spinal anesthesia-induced hypotension more precisely than the single parameters. Future research is necessary to determine whether this knowledge improves maternal and neonatal outcomes. TRIAL REGISTRATION: ChiCTR1900025191.

The use of preoperative inferior vena cava ultrasound to predict anaesthesia-induced hypotension: a systematic review.

Preoperative ultrasound assessment of inferior vena cava (IVC) diameter and the collapsi-bility index might identify patients with intravascular volume depletion. The purpose of this review was to gather the existing evidence to find out whether preoperative IVC ultrasound (IVCUS) derived parameters can reliably predict hypotension after spinal or general anaesthesia. PubMed was searched to identify research articles that addressed the role of IVC ultrasound in predicting hypotension after spinal and general anaesthesia in adult patients. We included 4 randomized control trials and 17 observational studies in our final review. Among these, 15 studies involved spinal anaesthesia and 6 studies involved general anaesthesia. Heterogeneity with respect to the patient populations under evaluation, definitions used for hypotension after anaesthesia, IVCUS assessment methods, and cut-off values for IVCUS-derived parameters to predict hypotension precluded pooled meta-analysis. The maximum and minimum reported sensitivity of the IVC collapsibility index (IVCCI) for predicting post-spinal hypotension was 84.6% and 58.8% respectively, while the maximum and minimum specificities were 93.1% and 23.5% respectively. For the prediction of hypotension after general anaesthesia induction, the reported ranges of sensitivity and specificity of IVCCI were 86.67% to 45.5% and 94.29% to 77.27%, respectively. Current literature on the predictive role of IVCUS for hypotension after anaesthesia is heterogeneous both in methodology and in results. Standardization of the definition of hypotension under anaesthesia, method of IVCUS assessment, and the cut-offs for IVC diameter and the collapsibility index for prediction of hypotension after anaesthesia are necessary for drawing clinically relevant conclusions.

The Impact of Blood Pressure Switching (from Controlled Hypotension to Late Elevated Blood Pressure) During Laparoscopic Sleeve Gastrectomy: Controlled Clinical Trial.

PURPOSE: Laparoscopic sleeve gastrectomy (LSG) is the most done bariatric procedure. Bleeding and leak are the most common associated complications. Elevation of systolic blood pressure (SBP) leads to discovering the bleeding sites but results in a bloody field and increases the operative time. Controlled hypotension shortens the operative time, reduces tissue edema, and improves field vision. We aimed to test controlled hypotension during LSG. MATERIAL AND METHODS: This was a randomized controlled trial that included 200 patients who were operated by LSG, randomly assigned to 2 equal groups: group 1, operated with controlled hypotensive anesthesia, and group 2, operated with elevated SBP to 140 mmHg. RESULTS: Of the patients, 162 (81%) were females, and 38 (19%) were male. The mean BMI was 45.7 kg/m2. The mean age was 41.7 years. The operative time was 36.43 ± 6.73 min in group 1 vs. 44.71 ± 5.47 min in group 2. The mean of total number of used gauzes and clips was 2.70 ± 3.49 in group 1 vs. 8.83 ± 3.15 in group 2. The mean amount of drain output was 37.65 ± 21.90 ml in group 1 vs. 74.00 ± 16.54 ml in group 2. The mean drop in the postoperative hematocrit was 0.08 in group 1 vs. 0.22 in group 2. The incidence of postoperative bleeding was 0% in group 1 vs. 1% in group 2. CONCLUSIONS: Controlled hypotensive anesthesia in LSG reduces the operative time, reduces the intraoperative bleeding, and improves the operative field.

Evaluating the Effect of a Dosing and Titration Protocol on Dexmedetomidine-Induced Hypotension in Trauma Patients.

BACKGROUND: Dexmedetomidine is an α-2 receptor agonist commonly used as a continuous infusion for sedation and analgesia; however, dose-dependent hypotension may limit its utility. Despite its widespread use, there is no consensus on appropriate dosing and titration. OBJECTIVE: The objective of this study was to determine whether a dexmedetomidine dosing and titration protocol is associated with decreased rates of hypotension in trauma patients. METHODS: This pre-post intervention study took place at a Level II trauma center in the Southeastern United States from August 2021 to March 2022 and included patients admitted by the trauma service to either the surgical trauma intensive care unit or intermediate care unit and received dexmedetomidine for greater than or equal to 6 hours. Patients were excluded if they were hypotensive or on vasopressors at baseline. The primary outcome was incidence of hypotension. Secondary outcomes included dosing and titration practices, initiation of a vasopressor, incidence of bradycardia, and time to goal Richmond Agitation Sedation Scale (RASS) score. RESULTS: Fifty-nine patients met inclusion criteria: 30 in the pre-intervention group and 29 in the post-intervention group. Protocol adherence in the post group was 34% with a median of one violation per patient. Rates of hypotension were similar between the groups (60% vs. 45%, p = .243) but significantly lower in the post group patients with zero protocol violations (60% vs. 20%, p = .029). The post group also had a significantly lower maximal dose (1.1 vs. 0.7 µg/kg/hr, p < .001). There were no significant differences in the initiation of a vasopressor, incidence of bradycardia, or time to goal RASS. CONCLUSION: Adherence to a dexmedetomidine dosing and titration protocol significantly decreased incidence of hypotension and maximal dexmedetomidine dose without increasing time to goal RASS score in critically ill trauma patients.

Use of dexmedetomidine for controlled hypotension in middle ear surgery: A systematic review and meta-analysis.

BACKGROUND: Microsurgical operations such as middle ear surgery rely heavily on visibility of the surgical field. Anesthetic techniques such as controlled hypotension have been developed to improve surgical field visibility by attempting to decrease bleeding. Many agents have been utilized to achieve controlled hypotension intraoperatively. Dexmedetomidine is a relatively newer agent which works on alpha-2 receptors to decrease sympathetic tone. This paper sought to determine the efficacy of dexmedetomidine for optimizing surgical field visibility in MES. METHODS: A comprehensive search strategy was used in PubMed, SCOPUS, CINAHL, and CENTRAL through August 9, 2022 for this systematic review and meta-analysis. INCLUSION CRITERIA: adult patients undergoing middle ear surgery with dexmedetomidine used for controlled hypotension to improve surgical field visibility. Risk of bias was assessed via Cochrane RoB 2. Meta-analysis of mean difference for surgical field scores and risk ratios for positive surgical field scores were used to compare dexmedetomidine with placebo or other agents. RESULTS: Fourteen studies were included in this review. Statistically significant mean difference was found to favor dexmedetomidine over placebo for Fromme-Boezaart surgical field scores. Statistically significant results were also demonstrated favoring dexmedetomidine over other agents in risk ratio for receiving positive surgical field scores, as well as surgeon and patient satisfaction scores. CONCLUSIONS: Controlled hypotension is an invaluable tool for surgical field visibility. Improved surgical field visibility was observed with dexmedetomidine compared with placebo and various other agents. Risk of sub-optimal bleeding scores was significantly lower with dexmedetomidine. Dexmedetomidine is effective at improving surgical field visibility in middle ear surgery.

5-Aminolevulinic acid hydrochloride enhances bupivacaine-induced hypotension in spontaneously hypertensive rats.

PURPOSE: Oral administration of 5-aminolevulinic acid hydrochloride (5-ALA-HCl) has been reported to enhance the hypotensive effects associated with anesthetics, especially in elderly hypertensive patients treated with antihypertensive agents. The present study aimed to clarify the effects of antihypertensive-agent- and anesthesia-induced hypotension by 5-ALA-HCl in spontaneously hypertensive rats (SHRs). METHODS: We measured blood pressure (BP) of SHRs and normotensive Wistar Kyoto (WKY) rats treated with amlodipine or candesartan before and after administration of 5-ALA-HCl. We also investigated the change in BP following intravenous infusion of propofol and intrathecal injection of bupivacaine in relation to 5-ALA-HCl administration. FINDINGS: Oral administration of 5-ALA-HCl significantly reduced BP in SHRs and WKY rats with amlodipine and candesartan. Infusion of propofol significantly reduced BP in SHRs treated with 5-ALA-HCl. Intrathecal injection of bupivacaine significantly declined SBP and DBP in both SHRs and WKY rats treated with 5-ALA-HCl. The bupivacaine-induced decline in SBP was significantly larger in SHRs compared with WKY rats. CONCLUSION: These findings suggest that 5-ALA-HCl does not affect the antihypertensive agents-induced hypotensive effect, but enhances the bupivacaine-induced hypotensive effect, especially in SHRs, indicating that 5-ALA may contribute to anesthesia-induced hypotension via suppression of sympathetic nerve activity in patients with hypertension.