Significant Decrease In HR Research Articles

Application of conscious sedation with dexmedetomidine and sufentanil in patient for plastic surgery

To observe the effectiveness of conscious sedation with dexmedetomidine and sufentanil in patients for plastic surgery. Forty patients scheduled for elective plastic surgery under conscious sedation were infused 1 µg/kg intravenously within 15 minutes as loading dose followed by a continuous infusion of dexmedetomidine (0.5 µg·kg⁻¹·h⁻¹) and sufentanil (0.07 µg·kg⁻¹·h⁻¹) respectively. Sufentanil 0.05 µg/kg and midazolam 0.025 mg/kg were administrated intravenously 5 minutes before local infiltration, and then a bolus of sufentanil or midazolam was given as needed to maintain OAA/S score of 11 during the procedure. The drug infusion was discontinued at 5 to 10 min before the end of the surgical procedure. The complications (i.e. anoxemia, apnea, bradycardia, restlessness, nausea, vomiting, crying and excitation), if any, anesthesia duration and drug consumption were recorded. On the first postoperative day, patients were asked to rate their satisfaction with the anesthetic management and whether they would choose to receive the same sedative analgesic medications and should they require a similar surgical procedure in the future. The OAA/S score decreased from 20.0 ± 0 to 11.5 ± 2.5 after patients being infused the loading dose of dexmedetomidine, and was maintained 10.5-11.1 during the procedure. At the end of the procedure, the OAA/S score return to 16.1 ± 2.8. The induction of sedation produced a significant decrease in HR (P < 0.05) and no significant changes in SBP, DBP and RR values (P > 0.05). There were 38 patients completed their procedures under conscious sedation, and there were incident of crying and bradycardia in 5 and 2 patients respectively. The anesthesia duration and consumption of dexmedetomidine, sufentanil and midazolam were (128 ± 47) min, (116 ± 43) µg, (10 ± 5) µg and (2 ± 1) mg respectively. In an interview on the first postoperative day, there were 13 patients complaining no memory, 17 patients complaining fuzzy memory and 8 patients complaining awake during the procedure, respectively. There were 92% of the patients willing to receive the same anesthetic technique again in the future. Conscious sedation with dexmedetomidine and sufentanil is an effective anesthetic technique in patients for plastic surgery.

Treatment with GH receptor antagonist in acromegaly: effect on cardiac arrhythmias

To evaluate the effects of short- and long-term treatment with pegvisomant (PEG) on arrhythmias in acromegalic patients resistant to long-term, high-dose therapy with somatostatin analogs (SA). Thirteen patients entered the study. all patients started peg at initial dose of 10MG daily and then titrated to 5MG every 6 weeks on the basis of IGF1. A standard 24-H electrocardiography registration was performed in all patients at baseline and after 6 AND 18 months of PEG to evaluate: mean (HR), maximum (MHR), and minimum (mHR) heart rate; pauses number (P) and duration (PD); supraventricular episodes (SEs) number and duration (SED); and ventricular ectopic beats (EB) number and duration (EBD). Left ventricular mass (LVM) was also evaluated by standard echocardiography. A slight but not significant decrease in HR, MHR, and mHR was observed after 6-month PEG, whereas a significant decrease in HR (P=0.03), MHR (P=0.05), and mHR (P=0.05) was found after 18-month PEG compared with baseline. LVM significantly (P=0.05) correlated with MRH (r=-0.50) after short-term treatment, and with HR (r=-0.54) and mHR (r=-0.55) after long-term treatment. Long-term PEG induced the complete recovery of arrhythmias recorded at baseline in one patient and the improvement of rhythm disorders developed after 6-month therapy in another patient. The prevalence of conduction disturbances passed from 15 to 7.7% after long-term PEG. Long-term treatment with PEG reduces HR, MHR, and mHR and improves rhythm abnormalities in acromegaly.

In vivo administration of KCNQ channel modulators influences blood pressure and mesenteric vascular resistance in rats

Recent work from our laboratory has shown that KCNQ channels are expressed in vascular smooth muscle cells where they contribute to vasopressin‐induced Ca2+ signaling. Suppression of KCNQ currents by vasopressin or pharmacological agents leads to membrane depolarization and activation of L‐type Ca2+ channels. To determine whether inhibition or activation of vascular KCNQ channels influences mesenteric vascular resistance (MVR) and mean arterial pressure (MAP) in vivo, adult Sprague‐Dawley rats were anesthetized with thiobutabarbital (125 mg/kg) and instrumented with femoral venous and arterial catheters for drug administration and arterial pressure determination. A perivascular blood flow probe was placed around the superior mesenteric artery. The KCNQ channel activator (flupirtine) or the inhibitor (linopirdine) was then administered in increasing concentrations (0.01 – 3.0 mg/kg i.v.). Flupirtine produced significant dose‐dependent decreases in MAP and MVR. Flupirtine (3.0 mg/kg) caused a 28.9 ± 1.2 mmHg decrease in MAP and a 33.5% decrease in MVR. In contrast, linopirdine produced dose‐dependent increases in MAP and MVR. A maximally effective concentration of linopirdine (1.0 mg/kg) produced a 9.9 ± 1.3 mmHg increase in MAP and a 19.2% increase in MVR. Flupirtine (3.0 mg/kg) also caused a modest, but significant decrease in HR of 26.3 ± 3.7 beat/min. Our results indicate that KCNQ channels contribute to tonic modulation of mesenteric vascular resistance and blood pressure. This work was supported by the NHLBI (R01 HL070670 to KLB) and the AHA (0715618Z to ARM).

No Relation between Therapeutic Response to Methylphenidate and its Cardiovascular Side Effects in Children with Attention-Deficit/Hyperactivity Disorder

Objective The aim of this study was to examine the relation between therapeutic response to methylphenidate (MPH) and its associated short term cardiovascular side effects (Systolic Blood Pressure-SBP, Diastolic Blood Pressure-DBP and Heart Rate-HR changes) in children with ADHD, based on the hypothesis that these parameters share common underlying mechanisms. Method A double-blind placebo-controlled crossover clinical trial of children 6 to 12 years old diagnosed with ADHD was done. The children were given one week of 0.5 mg/kg MPH and one week of placebo (divided into two equal doses, given twice every day). On the morning of the third day of each week, Blood Pressure (BP) and HR were recorded immediately before (at time 0) and after (at time 10 and 45 minutes) administration of MPH. Children were grouped into 4 categories according to their therapeutic response (large, moderate, mild or no response) to MPH. A mixed model analysis of variance was performed to determine whether response groups were different with regard to cardiovascular side effects. Results All variables were comparable among the four groups 10 min after treatment with MPH and with placebo. Small but significant (p &lt; 0.001) increases were seen in SBP (3.65 mm of Hg) and DBP (3.99 mm of Hg) 45 minutes after administration of MPH. A small but significant decrease in HR (3.3 beats per minute) was observed 45 min after administration of placebo. No significant differences in SBP, DBP and HR were found between response groups. Conclusions MPH causes a small but significant change in BP at 45 minutes after administration. No changes in HR were observed with MPH at 45 minutes. Responders to MPH treatment do not differ from non-responders in occurrence of BP and HR changes, at least within 45 minutes after administration and with the MPH dosage used in the study.

Chemical restraint of peccaries with tiletamine/zolazepam and xylazine or tiletamine/zolazepam and butorphanol

ObjectiveTo evaluate the use of a combination of tiletamine/zolazepam and xylazine (TZX) in collared and white-lipped peccaries and to compare its efficacy as an anesthetic technique with that of tiletamine/zolazepam and butorphanol (TZB). Study designProspective experimental trial. AnimalsSeven white-lipped peccaries (Tayassu pecari) (four females and three males) and four collared peccaries (Tayasu tajacu) (two males and two females). MethodsAnimal immobilization was attempted with TZX and TZB (IM) on two different occasions. Heart and respiratory rates (HR, RR), rectal temperature (RT), sedation, muscle relaxation, posture, auditory response and analgesia were evaluated every 15 minutes during immobilization. Induction, anesthesia, standing and walking time were determined after drug administration. ResultsDoses for white-lipped peccaries were 1.23 ± 0.26 mg kg−1 (mean ± SD) of TZ and 1.23 ± 0.26 mg kg−1 of X, and 1.46 ± 0.09 mg kg−1 of TZ and 0.14 ± 0.008 mg kg−1 of B; doses for collared peccaries were 1.51 ± 0.29 mg kg−1 of TZ and 1.51 ± 0.29 mg kg−1 of X and 1.68 ± 0.02 mg kg−1 of TZ and 0.17 ± 0.002 mg kg−1 of B. In white-lipped peccaries, both drug combinations provided a smooth induction and good immobilization for more than an hour. Anesthesia and standing times were significantly longer in animals given TZB, whereas walking time was significantly longer in animals given TZX. A significant decrease in HR was observed with both treatments. Respiratory rate decreased significantly with TZX, but the rate remained higher than with TZB. Induction and recovery quality in white-lipped peccaries was better with TZB than with TZX. Neither protocol provided adequate immobilization in collared peccaries. Conclusion and clinical relevanceAt the doses described, TZB is effective in providing a long period of immobilization, whereas TZX is adequate for short to medium immobilization in white-lipped peccaries. Neither drug combination was effective in collared peccaries at the doses given.