Maximum Mean Arterial Pressure Research Articles

Comparing equiosmolar hypertonic saline and mannitol for achieving brain relaxation in elective craniotomy patients: A systematic review and meta-analysis.

This study strives to provide a current and thorough assessment of the comparative efficacy and safety between equiosmolar quantities of hypertonic saline (HS) and mannitol in facilitating brain relaxation for patients undergoing elective craniotomies. This systematic review and meta-analysis, following preferred reporting items for systematic reviews and meta-analyses guidelines, compared the efficacy and safety of equiosmolar concentrations of mannitol and HS in elective craniotomies. PubMed, Scopus, Cochrane Library, ScienceDirect, and Proquest databases were searched using keywords related to mannitol, HS, and craniotomy. Results were analyzed through a random-effects model using Mantel-Haenszel risk ratio and standard mean difference. P < 0.05 was considered significant. Thirteen randomized controlled trials encompassing 965 patients (516 in the HS group and 448 in the mannitol group) were analyzed. The quality of studies was moderate-to-high, and no significant publication bias was observed. The primary outcome, brain relaxation, favored HS over mannitol without significant heterogeneity. Mannitol was associated with increased urine output compared to HS, irrespective of dose, with high heterogeneity. HS was linked to significantly reduced fluid input, confirmed by subgroup analysis with lower heterogeneity. No significant difference was found in serum osmolality between the two agents. Serum sodium (Na+) levels favored HS, whereas arterial blood Na+ levels also favored HS despite considerable heterogeneity. Maximum mean arterial pressure was higher with HS, but it displayed significant heterogeneity. Maximum central venous pressure showed no significant difference between the two agents, with moderate heterogeneity. HS appears more effective than mannitol in achieving brain relaxation, and it may offer advantages in fluid management and Na+ balance. Clinicians should consider these findings when selecting hyperosmotic agents for neurosurgical procedures. Further research is needed to address heterogeneity in certain outcomes and guide clinical practice.

Effect of gender factor on the effective dose of oxycodone for inhibiting responses to laryngeal mask airway insertion in elderly patients undergoing ophthalmic surgery

Objective: To evaluate the effect of gender factor on the effective dose of oxycodone for inhibiting responses to laryngeal mask airway (LMA) insertion in elderly patients undergoing ophthalmic surgery. Methods: From June to October 2021, 56 elderly patients, including 26 females and 30 males, aged from 65 to 80 (72±5) years, with a body mass index (BMI) of 18.5-24.9 kg/m2 and American Society of Anesthesiologists (ASA) physical status of Ⅰ or Ⅱ, who underwent elective ophthalmic surgery requiring LMA insertion in the Beijing Tongren Hospital affiliated to Capital Medical University were selected. Patients were divided into two groups according to gender: elderly female group and elderly male group. The modified Dixon sequential method was used. Oxycodone 0.10 mg/kg was injected intravenously in the first patient. Etomidate 0.2 mg/kg and cisatracurium 0.1 mg/kg were administrated 5 min later. After 3 min, the laryngeal mask was placed when the bispectral index (BIS) ≤60. The positive response to LMA insertion was defined as an increase in the maximum mean arterial pressure or the maximum heart rate>20% of the baseline value within 2 min after insertion. When the response to LMA insertion was positive, the dose of oxycodone was increased in the next patient, otherwise the dose was decreased, and the ratio of adjacent dose was 1.1. This process was repeated until the 7th turning point occurred. The half-maximal effective doses (ED50) and 95% confidence intervals (CI) of oxycodone for inhibiting laryngeal mask insertion were calculated and compared between the two groups. Meanwhile, the adverse reactions during anesthesia induction were observed. Results: All 26 patients in the elderly female group completed the test, but one patient in the elderly male group withdrew due to poor alignment of laryngeal mask, and finally 29 patients completed the study. There were 13 cases and 14 cases who had positive response to LMA insertion in the elderly female and male groups, respectively. The ED50 (95%CI) of oxycodone for inhibiting laryngeal mask insertion in the elderly male group was 0.096 (0.083-0.112) mg/kg, which was higher than that in the elderly female group [0.081 (0.073-0.098) mg/kg, P=0.008]. No adverse reactions such as choking cough, muscle tremor, hypoxemia, nausea, vomiting, reflux and aspiration occurred in 55 patients, except that one patient in the elderly female group had transient hypotension after induction, which improved after symptomatic treatment. Conclusion: The ED50 of oxycodone for inhibiting laryngeal mask insertion reaction in ophthalmic surgery is different in patients with different genders, which is 0.096 (0.083-0.112) mg/kg in the elderly male group and 0.081 (0.073-0.098) mg/kg in the elderly female group.

Pharmacological strategies to prevent haemodynamic changes after intubation in parturient women with hypertensive disorders of pregnancy: A network meta-analysis.

Objective: This network meta-analysis (NMA) aimed to determine the relative efficacy and safety of pharmacological strategies used to mitigate haemodynamic instability by intubation for general anaesthesia in hypertensive parturient women undergoing caesarean section.Methods: We considered randomised controlled studies comparing the effects of pharmacological strategies used to alleviate haemodynamic instability during intubation in parturient women with hypertensive disorders of pregnancy. The primary endpoints were maximum blood pressure and heart rate after intubation, and secondary endpoints were the Apgar scores at 1 and 5 min. NMA allowed us to combine direct and indirect comparisons between strategies.Results: Twelve studies evaluating nine pharmacological strategies in 619 patients were included. According to the surface under the cumulative ranking curve, the maximal mean arterial pressure was lowest for high-dose remifentanil (99.4%) followed by nitroglycerin (73.6%) and labetalol (60.9%). The maximal heart rate was lowest for labetalol (99.9%) followed by high dose of remifentanil (81.2%) and fentanyl (61.6%). Apgar score at 1 min was higher with low-dose than with high-dose remifentanil (mean difference, 0.726; 95% confidence interval, 0.056 to 1.396; I2=0.0%).Conclusions: High-dose remifentanil produces minimum blood pressure changes, while labetalol is most effective in maintaining normal heart rate in parturient women with hypertensive disorders of pregnancy during caesarean section under general anaesthesia.

Pharmacologic strategies to prevent hemodynamic changes after intubation in parturient women with hypertensive disorders of pregnancy: A systematic review and network meta-analysis protocol.

Hypertensive disorders of pregnancy are major health issues affecting mothers and infants. General anesthesia is inevitable for certain mothers with these conditions and they may exhibit pronounced hemodynamic instability, especially during induction and airway manipulation. The aims of this study are to combine direct and indirect comparisons of the efficacies of different medications used in attenuating reflex hemodynamic responses and generate intervention ranking by network meta-analysis (NMA). A systematic and comprehensive search will be performed using MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar databases, beginning from their inceptions to November 2019. Only randomized clinical trials evaluating the efficacy and safety of pharmacologic interventions for preventing hemodynamic changes after intubation in parturient women with hypertensive disorders of pregnancy will be included. The primary endpoints will be maximal mean arterial pressure (MAP) and maximal heart rate after intubation. Maximal systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and maternal/fetal blood gas analysis, as well as safety issues, including Apgar score at 1 minute and 5 minutes after delivery, will be also assessed.We will conduct both pairwise meta-analysis and network meta-analysis. We will use surface under the cumulative ranking curve (SUCRA) values and rankograms to present the hierarchy of pharmacologic interventions. A comparison-adjusted funnel plot will be used to assess the presence of small-study effects. The quality of the studies included will be assessed using the risk of bias tool 2.0. All statistical analyses will be performed using Stata SE, version 15.0 (StataCorp, College Station, TX). The results of this systematic review and NMA will be published in a peer-reviewed journal. This NMA will enable us to determine the order of effectiveness and safety of pharmacological interventions used in attenuating hemodynamic responses for mothers with hypertensive disorders of pregnancy. CRD42019136067.

The numerical study on specialized treatment strategies of enhanced external counterpulsation for cardiovascular and cerebrovascular disease

Traditional clinical mode of enhanced external counterpulsation is not targeted for different diseases. Specialized strategies in the treatment of enhanced external counterpulsation for coronary heart disease and cerebral ischemic stroke are supposed to be distinguished. The goal of treatment for coronary heart disease is diastolic blood pressure/systolic blood pressure = Q ≥ 1.2 after counterpulsation, while the goal of treatment for cerebral ischemic stroke is the improvement of mean arterial pressure. A computational lumped parameter model was established for the simulation of hemodynamic effect of enhanced external counterpulsation on two diseases. Vessel collapse was considered during the simulation of counterpulsation. Based on different pressurized and decompressed rate, pressurized moment, pressure duration, and pressure amplitude, different counterpulsation modes were applied to the model and the immediate hemodynamic effects were compared. Results showed that the pressure duration and pressure amplitude had most influence on two diseases. For cerebral ischemic stroke, the longer pressure duration and the higher pressure amplitude of thighs, the higher mean arterial pressure; while for coronary heart disease, the value of Q was highest when the pressure end moment was 0.6s during a 0.88-s cardiac cycle, and Q had a linear increase in the pressure amplitude of buttocks, but little change with the increase of calves and thighs pressure amplitude. For patients with coronary heart disease, the pressure duration was not supposed to be too long to avoid the increase of systolic blood pressure, and the improvement of pressure amplitude of buttocks could promise a positive treatment effect for coronary heart disease. While for patients with cerebral ischemic stroke, both the long pressure duration of each part and the high pressure amplitude of thighs could result in the systolic blood pressure and diastolic blood pressure have a certain increase, thus promoting the maximum mean arterial pressure and a best treatment. Graphical abstract The specialized treatment strategies of EECP for cardiovascular and cerebrovascular disease.

Dexmedetomidine Combined With Intravenous Anesthetics in Electroconvulsive Therapy: A Meta-analysis and Systematic Review.

The aim of this study was to investigate how the combined use of dexmedetomidine with intravenous anesthetics influences seizure duration and circulatory dynamics in electroconvulsive therapy (ECT). A literature search was performed to identify studies that evaluated the effect of dexmedetomidine on motor- or electroencephalogram (EEG)-based seizure durations and maximum mean arterial pressure (MAP) and heart rate (HR) after ECT. Moreover, recovery time and post-ECT agitation were evaluated. Six studies enrolling 166 patients in 706 ECT sessions were included. There was no significant difference in motor or EEG seizure duration between dexmedetomidine and nondexmedetomidine groups [motor: 6 studies; mean difference (MD), 1.62; 95% confidence interval (CI), -2.24 to 5.49; P = 0.41; EEG: 3 studies; MD, 2.34; 95% CI, -6.03 to 10.71; P = 0.58]. Both maximum MAP and HR after ECT were significantly reduced in the dexmedetomidine group (MAP: 6 studies; MD, -4.83; 95% CI, -8.43 to -1.22; P = 0.009; HR: 6 studies; MD, -6.68; 95% CI, -10.74 to -2.62; P = 0.001). Moreover, the addition of dexmedetomidine did not significantly prolong recovery time when the reduced-dose propofol was used (4 studies; MD, 63.27; 95% CI, -15.41 to 141.96; P = 0.12). The use of dexmedetomidine in ECT did not interfere with motor and EEG seizure durations but could reduce maximum MAP and HR after ECT. Besides, the addition of dexmedetomidine in ECT did not prolong recovery time when reduced-dose propofol was used. It might be worthwhile for patients to receive dexmedetomidine before the induction of anesthesia in ECT.

Intraoperative Hypotension During Second Stage of Deep Brain Stimulator Placement: Same Day versus Different Day Procedures

We evaluated blood pressure management associated with implantable pulse generator (IPG) procedure on same day (SD) versus different day (DD) from deep brain stimulation (DBS) placement. A retrospective chart review of 99 records for vasopressors given during IPG using a negative binomial regression model was performed. An association between SD versus DD, cumulative vasopressor dose, and minimum and maximum mean arterial pressure (MAP) were sought. No significant association between SD versus DD DBS and the number of times vasopressors were given during stage II, estimated ratio of means (CI) of 1.8 (0.9-3.5); P= 0.07. Day of stage II had no association with the cumulative dose of vasopressor given during stage II, with an estimated difference in means (CI) of 2.4 (-0.4 to 5.3). The SD group had a significantly lower mean of minimum stage II MAP compared with DD, with an estimated difference in means (CI) of-10.5 (-17.4 to-3.5; P < 0.001). There was no association with maximum stage II MAP, with an estimated difference in means (CI) of-2.8 (-17.6 to 12.0; P= 0.63). No difference in intraoperative vasopressor use was found between SD versus DD IPG placement, but the SD group had a significantly lower minimum MAP.

Incidence, aetiology and mortality secondary to hypertensive emergencies in a large-scale referral centre in Israel (1991-2010).

Hypertensive emergency (HE) is a life-threatening condition that requires immediate blood pressure (BP) reduction. Although it has been on the decline, the incidence of HE has recently increased in a few countries. The aim of the present retrospective study was to evaluate the incidence, aetiology and 1-year mortality of HE in a large medical centre over a 20-year period (1991-2010). The electronic medical records of all patient files who were hospitalized in the Chaim Sheba Medical Center in Israel from 1991 to 2010 with a primary diagnosis (at admission or discharge) of Malignant Hypertension, Hypertensive Emergency or Accelerated Hypertension were retrieved and analysed. The study interval was divided into four periods of 5 years each. Among 306 files reviewed, only 142 patients had a true HE. Average age at presentation was 63.3±16.5 years. Men were younger than women (59±16 vs 68±16 years; P<0.001). At presentation, most patients (80.3%) had been diagnosed with essential hypertension previously and were undertreated. Average maximum mean arterial pressure (MAP) was higher in men (169±22 mm Hg) than in women (161±17 mm Hg; P=0.026). The rate of HE decreased over the course of the study, from 12.7/100 000 admissions during 1991-1995 to 6.2/100 000 admissions (2006-2010). Similarly, 1-year mortality decreased from 16.7 to 3.6%. The rate of HE has decreased and the prognosis has improved over the last two decades. Appropriate BP control of patients with essential hypertension may further decrease the risk of HE.

Optimal blood pressure for favorable neurological outcome in adult patients following in-hospital cardiac arrest

BackgroundAdequate cerebral blood flow maintained by optimal blood pressure is important in neurological recovery for patients sustaining transient brain ischemia. Few clinical studies have investigated the relationship between blood pressure and neurological outcomes of patients resuscitated following cardiac arrest. MethodsThis was a retrospective observational study, from a single medical center, of adult patients between 2006 and 2012 who had in-hospital cardiac arrest and achieved sustained return of spontaneous circulation (ROSC). Multivariable logistic regression analysis was used to identify factors associated with a favorable neurological outcome at hospital discharge. Maximal mean arterial pressure (MAP) during the initial 24h after sustained ROSC was used for analysis. ResultsOf the 319 study patients, 56 (17.6%) achieved a favorable neurologic outcome. The mean MAP was 95mmHg. MAP above 85mmHg was found to correlate with a favorable neurological outcome (odds ratio [OR] 4.12, 95% confidence interval [CI] 1.47–14.39, p=0.01). For patients without arterial hypertension, the optimal MAP was between 85 and 115mmHg (OR 8.80, 95% CI 3.13–28.55, p<0.001); for patients with arterial hypertension, the threshold MAP for achieving a favorable neurological outcome was above 88mmHg (OR 4.04, 95% CI 1.41–13.03, p=0.01). ConclusionsThe blood pressure over the first 24h following resuscitation was correlated with neurological outcome. There may be a threshold blood pressure required to affect a favorable neurological outcome. The optimal blood pressure may be dependent on the presence or absence of arterial hypertension.

Abstract WP15: Dexmedetomidine versus Propofol for Monitored Anesthesia Care (MAC) during Endovascular Therapy for Acute Ischemic Stroke

INTRODUCTION: Previous studies have reported that compared to MAC, general anesthesia during intra-arterial therapy (IAT) for acute stroke is associated with worse outcomes. Propofol (PROP) and dexmedetomidine (DXM) are commonly used agents for MAC. While PROP can be associated with significant hemodynamic changes, DXM has been linked to cerebral vasoconstriction and transient decreases in brain oxygenation. We studied if there was a difference in outcomes in patients who underwent IAT for acute anterior circulation ischemic stroke (AAIS) under PROP or DXM MAC. Methods A prospectively maintained neuroendovascular database identified all patients who underwent IAT for AAIS under MAC from January 2010 to December 2011. Patient demographics, stroke characteristics, baseline NIHSS and mRS scores, pre and post-treatment stroke volumes on diffusion-weighted imaging (DWI), intra-procedural hemodynamics, discharge/30-day outcomes and mortality were collected. Descriptive statistics, one-way ANOVA and uni/multi-variate analysis were performed. Results The study included 52 patients, 30 treated with DXM and 22 with PROP. There were no significant differences in demographics, baseline mRS and NIHSS scores. Occlusion of the ICA terminus was more common in the PROP group and M1 segment occlusions in DXM. Revascularization was achieved in 86% of patients in the DXM group compared to 81% in PROP. Mean maximum Mean Arterial Pressure (MAP) was 133 and 139 mm Hg in DXM and PROP groups respectively. There were more hypotensive episodes in the DXM group and use of pressors was also significantly higher (80% vs 20%). There were no significant differences in DWI infarct growth (mean volume DXM 56cc, PROP 62cc). Functional outcomes and mortality were similar (30% mortality in DXM, 32% in PROP). Conclusion This is the first study comparing outcomes after IAT under MAC for AAIS using different agents. Although counterintuitive, our data suggests that DXM was associated with more hemodynamic changes than PROP. No differences in clinical or radiographic outcomes were found. This finding along with known cerebral vascoconstrictive effects of DXM should prompt cautious use of DXM in IAT. Larger prospective studies are warranted to confirm our observation.

509 L-CITRULLINE SUPPLEMENTATION REDUCED PERIPHERAL BLOOD PRESSURE IN CHINESE ADULTS WITH PREHYPERTENSION

Background: Prehypertension is a growing problem worldwide, and in Caucasian samples certain fruits or their supplements have demonstrated success in improving blood pressure. The aim of this study was to investigate the effect and mechanism of L-citrulline in regulating blood pressure among Chinese adults with prehypertension. Methods: From 369 patients attending a free physical examination, 40 prehypertensive participants were identified and randomly allocated to: an intervention group who received one-to-one health education plus 3 g L-citrulline; and a control group gave a placebo, both twice a day. 24-hour ambulatory blood pressure was collected at baseline and eight weeks later and concentration of nitric oxide synthase at eight weeks later. Results: L-citrulline reduced the maximum, minimum and office systolic blood pressure; the maximum diastolic blood pressure (p < 0.05); and maximum mean arterial pressure (p < 0.01). No significant effects were noted for the remaining blood pressure values notably the minimum diastolic blood pressure. Concentration of nitric oxide synthase was significantly up-regulated in the intervention group (p < 0.05) (Table 1).Conclusions: The results showed that L-citrulline automatically regulated blood pressure via improved nitric oxide production in Chinese adults with prehypertension.

Angiotensin I-Converting Enzyme Inhibitor Activity of Nutritive Plants in KwaZulu-Natal

Traditional herbal remedies still form an integral part of South African culture, hence necessitating reports on the scientific rationale for their uses. Organic and aqueous extracts from 16 nutritive plants found in KwaZulu-Natal, South Africa were screened for angiotensin I-converting enzyme (ACE) inhibitory activity using a fluorometric enzyme assay. A plant was considered to have potential antihypertensive properties if it inhibited the ACE enzyme and thus the conversion of angiotensin I to angiotensin II by greater than 50%. Eight of the 16 plants screened demonstrated ACE inhibitory activity and satisfied these criteria. These eight plants were then subjected to a gelatin salt block test for tannins to show that the ACE inhibitory activities were not due to the presence of tannins, as tannins also inhibit ACE activity. The plants that showed ACE inhibitory activity were Amaranthus dubius, Amaranthus hybridus, Asystasia gangetica, Galinsoga parviflora, Justicia flava, Oxygonum sinuatum, Physalis viscosa, and Tulbaghia violacea. T. violacea in particular shows promise with regards to ACE inhibition as in vivo administration of this extract showed only a 2.2% increase in maximum mean arterial pressure when compared to the 14.5% increase observed in the control group after co-administration with exogenous Ang I.

The Effect of Age on the Cardiovascular Responses Induced by Inhaled High Concentration of Desflurane

Background: The inhalation of high concentrations of desflurane transiently increases the cardiovascular responses. This study examined the effects of age on the cardiovascular response to desflurane. Methods: Eighty two patients were divided into one of three groups: under 3 years (Group 1), 20－50 years (Group 2), and over 65 years (Group 3). In each group, the inspired concentration of desflurane was increased abruptly to 12.0 vol% 2 minutes after a thiopental injection. The heart rate, blood pressure (BP), cardiac index (CI), End-tidal concentration of desflurane (ETdesf), and end-tidal concentration of CO2 were measured at the baseline and every 30 seconds. Results: The heart rate, BP, and CI increased transiently in the three groups compared with the baseline. The ETdesf increased more rapidly in Groups 1 and 3 than in Group 2. The ETdesf to reach the maximal mean arterial pressure (MAP) was highest in Group 3 among three groups. The relative maximal HR to the baseline value was similar in the three groups, but the relative maximal MAP to baseline value was significantly highest in the elderly patient group. The times to reach the maximal HR and BP were shortest in Group 1 among three groups. There were no significant differences in the CI between three groups. Conclusions: The inhalation of a high concentration of desflurane increases the HR, BP and CI transiently in all age groups. In pediatric patients, HR and BP increases more rapidly than in young adults and elderly patients. The relative maximal MAP to the baseline value is higher in elderly patients.

Haemodynamic changes induced by hyperbaric bupivacaine during lateral decubitus or supine spinal anaesthesia

Hypotension, the commonest side-effect of spinal anaesthesia, results from sympathetic denervation. This study compared patient positioning (supine vs. decubitus) on haemodynamic variables during spinal anaesthesia. After intravenous crystalloid preloading with 5 mL kg(-1), hyperbaric bupivacaine 0.5% 2.5 mL was injected intrathecally at the L2-3 or L3-4 interspace. Patients were then randomly assigned to be positioned immediately supine and horizontal for 30 min (Group SUP, n = 12), or remained in the lateral decubitus position (fractured hip dependent) for 30 min (Group LAT, n = 14). Systolic blood pressure, mean arterial pressure, and loss of sensation of pinprick sensation were recorded prior to induction of spinal anaesthesia (baseline) and at 1, 2, 3, 5, 10, 15, 30, 45, 60, 90 and 120 min after intrathecal injection. In Group SUP, the percent maximum systolic blood pressure (36 +/- 13%) and percent maximum mean arterial pressure decreases (27 +/- 13%) were significantly greater (P < 0.05) than in Group LAT (30 +/- 8% and 23 +/- 11%, respectively). Additionally, there was a borderline significant delay in the time to maximum systolic blood pressure decrease in Group LAT (38 +/- 30 min) when compared with Group SUP (20 +/- 17 min, P = 0.06), while the total dose of ephedrine required in the SUP group (30 mg) was greater than that required in the LAT group (15 mg, P = 0.05). In Group LAT patients, the mean level of denervation on the operative side extended 2 dermatomes more cephalad than in Group SUP. Lateral positioning for spinal anaesthesia delays the onset of hypotension, while requiring smaller total doses of vasoconstrictors for blood pressure maintenance.

Prazosin potentiates the acute hypotensive effects of nitroglycerin but does not attenuate nitrate tolerance in normal conscious rats.

Sympathetic activation has been suggested as a mechanism of acute nitrate tolerance, but the available literature is not definitive. We investigated the effects of prazosin, an alpha1-adrenoceptor antagonist, on acute nitroglycerin (NTG) hemodynamics and tolerance development in normal conscious rats. The effect of prazosin bolus injection (300 microg/kg) on NTG hemodynamics was first determined after acute dosing. The extent of maximal mean arterial pressure (MAP) response and the duration of drug-induced hypotension to NTG bolus doses (5, 15, and 30 microg) were measured before and after prazosin. In separate studies, the effects of prazosin on NTG tolerance development were examined. Rats received either 10 microg/min NTG or vehicle infusion for 5 hours after predosing with prazosin (300 microg/kg). Maximal MAP response to the hourly 30-microg NTG i.v. bolus challenge dose (CD) was determined before and after prazosin, and during NTG or vehicle infusion. Our results showed that bolus doses of NTG (at 5, 15, and 30 microg) dose-dependently decreased maximal MAP by 20.8 +/- 5.8, 26.1 +/- 5.0, and 30.6 +/- 5.7 mm Hg, respectively. Prazosin caused an average of 16 mm Hg depression in MAP, and it only slightly potentiated the hypotensive effects of bolus doses of NTG both after acute dosing and during continuous infusion. Prazosin treatment prolonged the duration of NTG-induced MAP response by about 4-fold for all NTG doses examined (P < 0.01 versus corresponding dose before prazosin, ANOVA). In both prazosin-treated and untreated groups, NTG infusion significantly attenuated the MAP response of the NTG CD starting from 1 hour of infusion (P < 0.001 versus 0 hour response, ANOVA), confirming tolerance development. In the presence of NTG tolerance development, prazosin no longer enhanced the apparent duration of NTG action. The hypotensive effect produced by the 30-microg NTG CD lasted for 7 +/- 2 and 10 +/- 2 seconds for prazosin-treated and untreated groups, respectively (P > 0.05, ANOVA). Our results showed that, in both NTG-tolerant and control animals, prazosin only slightly potentiated the maximum hypotensive effects of a challenge NTG dose, but did not significantly alter the pharmacodynamics of NTG-induced hemodynamic tolerance. Thus, in our animal model, sympathetic blockade by prazosin neither prevented nor attenuated in vivo tolerance induced by NTG.

A randomized comparative trial of first-dose response to Angiotensin- Converting Enzyme Perindopril and Captopril in Indonesian heart failure patients

Several large placebo-controlled trials have confirmed that angiotensin converting enzyme (ACE) inhibitors significantly reduce mortality aid morbidity in all functional grades of congestive heart failure (CHF), nevertheless only a proportion of patients who may benefit from treatment are priscribed an ACE inhibitor. One of the perceived difficulties is the occurrence of first-dose hypotension in susceptible patients. A double-blind, randomised, single-dose therapy, parallel-group study was conducted with the aim to compare the first-dose responses to low dose ACE inhibitors captopril and perindopril in patients with stable chronic heart failure. Seventy patients (New York Heart Association class I-IV) were included. Blood pressure was recorded every 15 minutes 2 hours before starting treatment. The mean of these readings was taken as the baseline blood pressure. Patients were randomised to receive a single-dose of captopril 6.25 mg or perindopril 2 mg. After taking the drug, blood pressure was monitored every 15 minutes for 2 hours, every 30 minutes during 5 hours then hourly after 2 hours. The maximum mean arterial pressure fall from baseline of perindopril was 0.85 mmHg compared to captopril 4.60 mmHg. The maximum mean systolic fall from baseline of perindopril was 3 '31 'mmHg compared to captopril 6.76 mmHg while the maximum mean diastolic fall from baseline of perindopril was 1.08 mmHg compared to captopril 2.63 mmHg. The hypotensive effect of the captopril group started soon after dosing and reached its maximum after 1 to 2 hours while perindopril showed slight reduction of systolic after 1 hour and slight reduction of diastolic after 4 hours. Compared to captopril, perindopril seemed to be less likely to cause first-dose hypotension in patients with heart failure. (Med J Indones 2002; 11: 19-23)Keywords: first dose hypotension, perindopril, captopril, chronic heart failure

Effects of lightwand (Trachlight) compared with direct laryngoscopy on circulatory responses to tracheal intubation

We compared the effects of the lightwand technique on circulatory responses to tracheal intubation with those of direct-vision laryngoscopy. Forty adult patients received propofol and vecuronium, and their lungs were ventilated for 2 min via a mask with 5% sevoflurane in oxygen, after which the trachea was intubated orally using either the lightwand (Trachlight, n = 20) or the Macintosh laryngoscope (n = 20). Maximum mean arterial pressure changes did not differ between groups during (lightwand group, 25 (SD 21) mm Hg vs laryngoscopy group, 23 (19) mm Hg) and after (21 (24) mm Hg vs 21 (16) mm Hg) tracheal intubation. Maximum heart rate changes were similar for groups during (16 (14) beat min-1 vs 16 (15) beat min-1) and after (2 (11) beat min-1 vs 7 (19) beat min-1) tracheal intubation. There were no differences between the lightwand technique and direct-vision laryngoscopy in changes in mean arterial pressure and heart rate during and after tracheal intubation. We conclude that the effects of the lightwand technique on circulatory responses to tracheal intubation were similar to those of direct-vision laryngoscopy.

Mechanisms for preserved cerebrovascular autoregulation during hypertension in rats after sinoaortic denervation.

1. Cerebral blood flow (CBF) and cerebrovascular resistance (CVR) autoregulate to higher levels of arterial pressure (AP) in rats after sinoaortic denervation (SAD) than in intact rats. 2. Potential mechanisms for this phenomenon were studied by monitoring CBF by laser flowmetry while increasing AP in rats after: (i) SAD; (ii) SAD plus bilateral removal of the superior cervical ganglia; (iii) SAD plus interruption of all renal vessels and nerves (renal isolation); (iv) SAD plus sympathectomy and renal isolation; and (v) intravenous treatment with the nitric oxide synthase inhibitor L-nitroarginine (LNA). 3. Compared to intact control rats autoregulation persisted to higher absolute levels of AP in SAD rats with isolation of the kidneys and resistance did not fall significantly below that in rats with SAD alone. 4. Effects of SAD on autoregulation were not altered by combining renal isolation with an interruption of sympathetics. 5. LNA did not affect the baroreflex but blocked a breakthrough of autoregulation even at a maximal mean AP (MAP) of 189 +/- 2 mmHg. 6. Breakthrough occurred in animals pretreated with LNA plus L-arginine but not in animals given LNA plus D-arginine. 7. These data are consistent with a role of the baroreflex in the expression of breakthrough and suggest that breakthrough may result from release of nitric oxide or a nitric oxide donor.

Adult Hemolytic-Uremic Syndrome

Adult hemolytic-uremic syndrome is a serious, poorly understood disease with a high and variable mortality. We studied several demographic, clinical, and treatment variables, related them to outcome, and developed a new classification. We analyzed data from 37 patients admitted from 1981 to 1991 who fulfilled four criteria (age > 16 years, microangiopathic hemolytic anemia, creatinine level > 150 mumol/L [> 1.7 mg/dL], and no artificial heart valve). Three outcome variables were studied (survival vs death, recurrence vs no recurrence, and chronic renal failure vs no chronic renal failure). Eleven (30%) of the patients died, 10 (27%) needed dialysis, five (14%) developed chronic renal failure, and nine (24%) had recurrent episodes. Patients who presented with colitis did not die or have recurrences, but they developed chronic renal failure as often as other patients. Patients with hemolytic-uremic syndrome secondary to other diseases had the worst survival and the most recurrences. Those without any triggering factor (primary cases) were in between. In multivariate analysis, hemolytic-uremic syndrome secondary to colitis, a higher white blood cell count at admission, and a high maximum mean arterial pressure were associated with good survival prognosis. The persistence of the trigger of adult hemolytic-uremic syndrome sets the stage for outcome. If the trigger is transient (such as Escherichia coli colitis), the disease will not recur and is rarely lethal. If no trigger is apparent (primary hemolytic-uremic syndrome) or the trigger persists (systemic lupus erythematosus and cancer), the syndrome has a high mortality and often recurs. We suggest a new classification: (1) extrinsic hemolytic-uremic syndrome: (a) toxic, (b) infectious; (2) intrinsic hemolytic-uremic syndrome: (a) primary, (b) secondary. The use of this classification, combined with simple data obtained at presentation and a further division of the cause as transient or persistent and irreversible, may improve the selection of therapy.

Reduction of mismatch of global ventilation and perfusion on exercise is related to exercise capacity in chronic heart failure.

The inability to match lung perfusion to ventilation because of a reduced cardiac output on exercise contributes to reduced exercise capacity in chronic heart failure. To quantify ventilation to perfusion matching at rest and at peak exercise in patients with chronic heart failure and relate this to haemodynamic and ventilatory variables of exercise capacity. Eight men in New York Heart Association class II underwent maximal bicycle ergometry with expired gas analysis. On separate days, ventilation and perfusion gamma camera imaging was performed at rest, and at 80% of previous peak exercise heart rate during bicycle ergometry. The vertical distribution of mismatch between ventilation and perfusion (V/Q) was estimated from subtracted profiles of activity (ventilation and perfusion) to derive a numerical index of global mismatch. Maximal mean (SD) oxygen consumption on bicycle ergometry was 16.0 (4.5) ml min-1 kg-1. There was a reduction in the global V/Q mismatch index from 23.96 (5.90) to 14.88 (7.90) units (p < 0.01) at rest and at peak exercise. Global V/Q mismatch index at peak exercise correlated negatively with maximal minute ventilation (R = -0.90, p < 0.01) and with maximal mean arterial pressure (R = -0.79, p < 0.05), although no relation was seen with maximal oxygen consumption. The reduction in global V/Q mismatch index from rest to peak exercise correlated with maximal oxygen consumption (R = 0.88, p < 0.01), and with maximal minute ventilation (R = 0.87, p < 0.01). During exercise in patients with chronic heart failure, there is a reduction in the global V/Q mismatch index. A lower global V/Q mismatch index at peak exercise is associated with higher maximal ventilation. The reduction in global V/Q mismatch index on exercise correlates well with maximal exercise capacity. This may imply that the inability to perfuse adequately all regions of lung on exercise and match this to ventilation is a factor determining exercise capacity in chronic heart failure.