Hemodynamic and respiratory changes following dexmedetomidine administration during general anesthesia: sevoflurane vs desflurane

BACKGROUND: The current study evaluates the hemodynamic and respiratory effects of dexmedetomidine (DEX) when administered to children anesthetized with sevoflurane (SEVO) or desflurane (DES). METHODS: After tracheal intubation and spontaneous ventilation, DEX (0.5 microg x kg(-1)) was administered over 5 min. Heart rate (HR), systolic blood pressure (sBP), diastolic blood pressure (dBP), and endtidal carbon dioxide (P(E)CO(2)) were monitored and recorded prior to DEX (time 0) and again at 5, 10, and 15 min after DEX. RESULTS: The cohort included 80 children (1-12 years of age) anesthetized with SEVO (n = 40) or DES (n = 40). The lowest HR from time 0 to time 15 was less in patients anesthetized with SEVO compared with DES (104 +/- 16 b x min(-1) in the SEVO/DEX group vs 120 +/- 17 b x min(-1) in the DES/DEX group, < 0.01). Although both sBP and dBP decreased following the administration of DEX to patients anesthetized with either SEVO or DES, there was no difference in sBP or dBP between the two groups. Likewise, no evidence was found for changes in the P(E)CO(2) during the study period. CONCLUSIONS: The administration of DEX (0.5 microg x kg(-1)) results in a lower HR in patients anesthetized with SEVO compared with DES. No evidence was found for differences in sBP, dBP, or P(E)CO(2) during spontaneous ventilation with 1 MAC of SEVO vs DES.     

Modifications of the hemodynamic consequences of theophylline intoxication with landiolol in halothane-anesthetized dogs

PURPOSE: To examine the effect of landiolol (ONO-1101), a new ultra-short acting, highly selective beta1 blocker, on hemodynamic response to acute theophylline intoxication in anesthetized dogs. METHODS: Thirty-four dogs were studied during halothane anesthesia. Aminophylline (50 mg x kg(-1) over 20 min followed by infusion at 1.75 mg x kg(-1) x hr(-1)) was administered as a model of acute theophylline intoxication. Dogs were randomly enrolled into four landiolol groups (0, 1, 10, 100 microg x kg(-1) x min(-1)) to treat tachyarrhythmias. Hemodynamic variables, heart rate (HR), systemic blood pressure (SBP), pulmonary artery pressure, pulmonary artery occlusion pressure, and cardiac output (CO) were measured along with plasma concentrations of theophylline, epinephrine, and norepinephrine. RESULTS: After 60 min, plasma concentration of theophylline reached 46.6+/-4.0 (mean +/- SD) microg x ml(-1), HR increased from 129+/-21 to 193+/-27 bpm (P<0.0001) and CO increased from 1.6+/-0.5 l x min(-1) to 2.1+/-0.4 l x min(-1) (P<0.0001), whereas SBP decreased from 139+/-25 to 121+/-25 mm Hg (P<0.0001), with decreasing systemic vascular resistance. After intoxication, plasma epinephrine concentration increased from 125 +/-112 to 325+/-239 pg x ml(-1) (P<0.0001), and norepinephrine concentration from 103+/-61 to 133+/-61 pg x ml(-1) (P<0.0011). Landiolol 10 microg x kg(-1) x min(-1) decreased HR to pre-intoxication level, whereas HR returned to the intoxication baseline by 30 min after cessation of landiolol infusion. CONCLUSIONS: Landiolol controlled tachyarrhythmias associated with theophylline toxicity. The optimal effective dose of landiolol was 10 microg x kg(-1) x min(-1).     

Dopexamine hydrochloride does not modify hemodynamic response or tissue oxygenation or gut permeability during abdominal aortic surgery

PURPOSE: To assess the effects of intraoperative infusion of dopexamine (a DA-1 and B2 adrenoreceptor agonist) on hemodynamic function, tissue oxygen delivery and consumption, splanchnic perfusion and gut permeability following aortic cross- clamp and release. METHODS: In a randomised double blind controlled trial 24 patients scheduled for elective infrarenal abdominal aortic aneurysm repair were studied in two centres and were assigned to one of two treatment groups. Group I received a dopexamine infusion starting at 0.5 microg x kg(-1) x min(-1) increased to 2 microg x kg(-1) x min(-1) maintaining a stable heart rate; Group II received a placebo infusion titrated in the same volumes following induction of anesthesia. Measured and derived hemodynamic data, tissue oxygen delivery and extraction and gut permeability were recorded at set time points throughout the procedure. RESULTS: Dopexamine infusion (0.5 -2 microg x kg x min(-1)) was associated with enhanced hemodynamic function (MAP 65 +/- 5.5 vs 92 +/- 5.7 mm Hg, P = <0.05) only during the period of aortic cross clamping. However, during the most part of infrarenal abdominal aortic surgery, dopexamine did not reduce systemic vascular resistance index, mean arterial pressure nor oxygen extraction compared with the control group. The lactulose/ rhamnose permeation ratio was elevated above normal in both groups (0.22 and 0.29 in groups I and II respectively). CONCLUSIONS: Dopexamine infusion (0.5 -2 microg x kg(-1) x min(-1)) did not enhance hemodynamic function and tissue oxygenation values during elective infrarenal abdominal aortic aneurysm repair.     

Intravenous magnesium sulfate administration reduces propofol infusion requirements during maintenance of propofol-N2O anesthesia: part I: comparing propofol requirements according to hemodynamic responses: part II: comparing bispectral index in control and magnesium groups

BACKGROUND: The authors investigated whether an intravenous administration of magnesium sulfate reduces propofol infusion requirements during maintenance of propofol-N2O anesthesia. METHODS: Part I study: 54 patients undergoing total abdominal hysterectomy were randomly divided into two groups (n = 27 per group). The patients in the control group received 0.9% sodium chloride solution, whereas the patients in the magnesium group received magnesium (50 mg/kg as a bolus, then 8 mg x kg(-1) x h(-1)). To maintain mean arterial blood pressure (MAP) and heart rate (HR) at baseline value, the propofol infusion rate was changed when the MAP or the HR changed. The amount of propofol infused excluding the bolus dosage was divided by patient's body weight and total infusion time. Part II study: Another 20 patients were randomly divided into two groups (n = 10 per group). When the MAP and HR had been maintained at baseline value and the propofol infusion rate had been maintained at 80 microg x kg(-1) x min(-1) (magnesium group) and 160 microg x kg(-1) x min(-1) (control group), bispectral index (BIS) values were measured. RESULTS: Part I: The mean propofol infusion rate in the magnesium group (81.81 +/- 13.09 microg x kg(-1) x min(-1)) was significantly less than in the control group (167.57 +/- 47.27). Part II: BIS values in the control group (40.70 +/- 3.89) were significantly less than those in the magnesium group (57.80 +/- 7.32). CONCLUSION: Intravenous administration of magnesium sulfate reduces propofol infusion requirements. These results suggest that magnesium administration may have an effect on anesthesia or analgesia and may be a useful adjunct to propofol anesthesia.     

Adenosine and amrinone reverse felypressin-induced depression of myocardial tissue oxygen tension in dogs

PURPOSE: To determine whether continuous infusion of adenosine triphosphate (ATP), nitroglycerin (NTG) or amrinone (AM) would ameliorate the reductions in coronary blood flow (CBF) and myocardial oxygen tension (PmO2) induced by felypressin. METHODS: Seven open-chest dogs were studied under urethane and alpha-chloralose anesthesia. Hemodynamic variables including heart rate (HR), systolic blood pressure, diastolic blood pressure (DBP), mean pulmonary artery pressure, pulmonary capillary wedge pressure, CBF (ultrasound flowmetry), PmO2(polarography) and cardiac output (thermodilution method) were recorded. Felypressin was infused in a loading dose of 6 mIU x kg(-1) for five minutes and then continued at 0.2 mIU x kg(-1) x min(-1). After 30 min felypressin infusion, each agent was administered for 15 min to evaluate hemodynamic changes. Infusions were 100 and 200 microg x kg(-1) x min(-1) for ATP, 2.5 and 5 microg x kg(-1) x min(-1) for NTG, and 10 and 20 microg x kg(-1) x min(-1) for AM. RESULTS: After felypressin DBP increased by 17 +/- 5 (mean +/- SD) %; CBF decreased by 49 +/- 9%; CI decreased by 40 +/- 13%; HR decreased by 29 +/- 11%; PmO2 in the inner layer decreased by 21 +/- 7%. The Cl and CBF returned to baseline afterATP 100 and 200 microg x kg(-1) x min(-1), AM 10 and 20 microg x kg(-1) x min(-1), but not after NTG. The PmO2 in the inner layer returned to the baseline value by any infusion except for NTG 5 microg x kg(-1) min(-1) CONCLUSION: Adenosine and amrinone, but not nitroglycerin reverses the adverse cardiovascular effects of felypressin.     

The use of dexmedetomidine in pediatric cardiac surgery

We tested dexmedetomidine, an alpha2 agonist, for its ability to decrease heart rate, arterial blood pressure, and neuroendocrinal responses during pediatric cardiac surgery. In a randomized, placebo-controlled study, 30 pediatric patients undergoing open heart surgery were randomly assigned to one of two equal groups. The control group received saline, whereas the treatment group (DEX group) received an initial bolus dose of dexmedetomidine (0.5 microg/kg) over 10 min, followed immediately by a continuous infusion of 0.5 microg.kg(-1).h(-1). Arterial blood pressure, heart rate, and sequential concentrations of circulating cortisol, epinephrine, norepinephrine, and blood glucose were measured. Relative to baseline, arterial blood pressure and heart rate decreased significantly after the administration of dexmedetomidine through skin incision. In the control group, patients' heart rate and arterial blood pressure measures increased after skin incision until the end of bypass (P < 0.05). In both groups, plasma cortisol, epinephrine, norepinephrine, and blood glucose increased significantly relative to baseline, after sternotomy, and after bypass. However, the values were significantly higher in the control group compared with the DEX group (P < 0.05). In conclusion, intraoperative dexmedetomidine infusion attenuated the hemodynamic and neuroendocrinal response to surgical trauma and cardiopulmonary bypass in pediatric patients undergoing corrective surgery for congenital heart disease.     

Dopamine stabilizes milrinone-induced changes in heart rate and arterial pressure during anaesthesia with isoflurane

BACKGROUND AND OBJECTIVE: Phosphodiesterase-III inhibitors and dobutamine effectively improve cardiac function in patients with cardiac failure, but they are limited by possible hypotensive effects. We tested the hypothesis that dopamine contributes to stabilizing milrinone-induced haemodynamic changes. METHODS: Nine patients undergoing major surgery were anaesthetized using nitrous oxide and oxygen supplemented with isoflurane 1-2%. After baseline haemodynamics were recorded, milrinone (25 or 50 microg kg(-1)) was administered over 10min, followed by a continuous infusion (0.5 microg kg(-1) min(-1). The second set of haemodynamic values was measured 50 min after beginning the continuous infusion of milrinone. Dopamine (4 microg kg(-1) min(-1)) was then administered with milrinone. RESULTS: Milrinone significantly increased the heart rate from 81 +/- 8 to 102 +/- 16beats min(-1), but it decreased the mean arterial pressure from 83 +/- 10 to 66 +/- 10 mmHg and systemic vascular resistance (P < 0.05 for each). The pulmonary capillary wedge pressure, cardiac index and pulmonary vascular resistance did not change significantly. The addition of dopamine to the milrinone infusion significantly decreased the heart rate (94 +/- 12 beats min(-1)) and increased the mean arterial pressure (82 +/- 11 mmHg). Dopamine and milrinone, but not milrinone alone, significantly increased the cardiac index and the rate-pressure product. CONCLUSIONS: The combination regimen of milrinone and dopamine improved cardiac function, and changes in heart rate and mean arterial pressure induced by milrinone were attenuated by dopamine. The results suggest that a combination regimen of milrinone and dopamine rather than milrinone alone should be used to maintain arterial pressure.     

Ornipressin (Por 8): An efficient alternative to counteract hypotension during combined general/epidural anesthesia

We sought to evaluate the efficacy and side effect profile of a small dose of ornipressin, a vasopressin agonist specific for the V1 receptor, administered to reverse the hypotension associated with combined general/epidural anesthesia. A total of 60 patients undergoing intestinal surgery were studied. After the induction of anesthesia, 7-8 mL of bupivacaine 0.5% with 2 microg/kg clonidine and 0.05 microg/kg sufentanil after an infusion of 5 mL of bupivacaine 0.06% with 0.5 microg x kg(-1) x h(-1) clonidine and 0.1 microg/h of sufentanil were administered by an epidural catheter placed at T7-8 vertebral interspace. When 20% reduction of baseline arterial blood pressure developed, patients were randomly assigned to receive, in a double-blinded design, dopamine started at 2 microg x kg(-1) x min(-1), norepinephrine started at 0.04 microg x kg(-1) x min(-1), or ornipressin started at 1 IU/h. Fifteen patients presenting without hypotension were used as control subjects. Beside routine monitoring, S-T segment analysis, arterial lactacidemia, and gastric tonometry were performed. Ornipressin restored arterial blood pressure after 8 +/- 2 vs 7 +/- 3 min in the norepinephrine group and 11 +/- 3 min in the dopamine group (P < 0.05). This effect was achieved with 2 IU/h of ornipressin in most of the patients (11 of 15). Ornipressin did not induce any modification of the S-T segment; however, it significantly increased intracellular gastric PCO(2) (P < 0.05), indicating splanchnic vasoconstriction. Implications: In the population studied, small-dose ornipressin was effective to restore arterial blood pressure without causing major ischemic side effects.     

Comparison of adenosine and remifentanil infusions as adjuvants to desflurane anesthesia

BACKGROUND: Because adenosine has been alleged to produce both anesthetic and analgesic sparing effects, a randomized, double-blinded study was designed to compare the perioperative effects of adenosine and remifentanil when administered as intravenous adjuvants during general anesthesia for major gynecologic procedures. METHODS: Thirty-two women were assigned randomly to one of two drug treatment groups. After premedication with 0.04 mg/kg intravenous midazolam, anesthesia was induced with 2 micro/kg intravenous fentanyl, 1.5 mg/kg intravenous propofol, and 0.6 mg/kg intravenous rocuronium, and maintained with desflurane, 2%, and nitrous oxide, 65%, in oxygen. Before skin incision, an infusion of either remifentanil (0.02 microg x kg(-1) x min(-1)) or adenosine (25 microg x kg(-1) x min(-1)) was started and subsequently titrated to maintain systolic blood pressure, heart rate, or both within 10-15% of the preincision values. RESULTS: Adenosine and remifentanil infusions were effective anesthetic adjuvants during lower abdominal surgery. Use of adenosine (mean +/- SEM, 166+/-17 microg x kg(-1) x min(-1)) was associated with a significantly greater decrease in systolic blood pressure and higher heart rate values compared with remifentanil (mean +/- SEM, 0.2+/-0.03 microg kg(-1) x min(-1)). Total postoperative opioid analgesic use was 45% and 27% lower in the adenosine group at 0-2 h and 2-24 h after surgery, respectively. CONCLUSIONS: Adjunctive use of a variable-rate infusion of adenosine during desflurane-nitrous oxide anesthesia was associated with acceptable hemodynamic stability during the intraoperative period. Compared with remifentanil, intraoperative use of adenosine was associated with a decreased requirement for opioid analgesics during the first 24 h after operation.     

Remifentanil requirements during sevoflurane administration to block somatic and cardiovascular responses to skin incision in children and adults

BACKGROUND: The authors found no studies comparing intraoperative requirements of opioids between children and adults, so they determined the infusion rate of remifentanil to block somatic (IR50) and autonomic response (IRBAR50) to skin incision in children and adults. METHODS: Forty-one adults (aged 20-60 yr) and 24 children (aged 2-10 yr) undergoing lower abdominal surgery were studied. In adults, anesthesia induction was with sevoflurane during remifentanil infusion, whereas in children remifentanil administration was started after induction with sevoflurane. After intubation, sevoflurane was administered in 100% O2 and was adjusted to an ET% of 1 MAC-awake corrected for age at least 15 min before surgery. Patients were randomized to receive remifentanil at a rate ranging from 0.05 to 0.35 microg x kg(-1) x min(-1) for at least 20 min before surgery. At the beginning of surgery, only the skin incision was performed, and the somatic and autonomic responses were observed. The somatic response was defined as positive with any gross movement of extremity, and the autonomic response was deemed positive with any increase in heart rate mean arterial pressure equal to or more than 10% of preincision values. Using logistic regression, the IR50 and IRBAR50 were determined in both groups of patients and compared with unpaired Student t test. A P value less than 0.05 was considered significant. RESULTS: The IR50 +/- SD was 0.10 +/- 0.02 microg x kg(-1) x min(-1) in adults and 0.22 +/- 0.03 microg x kg(-1) x min(-1) in children (P < 0.001). The IRBAR50 +/- SD was 0.11 +/- 0.02 microg x kg(-1) x min(-1) in adults and 0.27 +/- 0.06 microg x kg(-1) x min(-1) in children (P < 0.001). CONCLUSIONS: To block somatic and autonomic responses to surgery, children require a remifentanil infusion rate at least twofold higher than adults.     

Effects of dobutamine on hemodynamics and left ventricular performance after cardiopulmonary bypass in cardiac surgical patients.

BACKGROUND: Dobutamine is commonly used to improve ventricular performance after cardiopulmonary bypass. The authors determined the effect of dobutamine on hemodynamics and left ventricular performance immediately after cardiopulmonary bypass in patients undergoing coronary artery bypass graft surgery. METHODS: One hundred patients received sequential 3-min infusions of dobutamine at 0-40 microg x kg(-1) x min(-1) immediately after cardiopulmonary bypass. Ten additional patients who received no dobutamine served as controls. Hemodynamics and left ventricular performance (fractional area change by transesophageal echocardiography, stroke volume index, and thermodilution cardiac index) were measured. Mixed-effects modeling accounted for repeated-measures data and interindividual differences and allowed for potential effects of covariates. RESULTS: Heart rate increased in a dose-dependent manner. The slope of HR versus dobutamine dose was steeper in individuals in whom peak dobutamine dose was not reached compared with that in the remaining individuals; slope decreased 2.71 +/- 0.68% per year of age. Dobutamine affected blood pressure minimally, but slightly decreased pulmonary capillary wedge pressure and central venous pressure. Systemic vascular resistance initially increased with dobutamine 10 microg x kg(-1) x min(-1) and remained constant with larger doses. Dobutamine produced a dose-dependent increase in left ventricular performance, primarily by increasing heart rate, because stroke volume index decreased with dobutamine dose. CONCLUSION: Our results suggest that the response to graded dobutamine infusion in the post-cardiopulmonary bypass period differs from that previously reported. After cardiopulmonary bypass, the dominant mechanism by which dobutamine improves left ventricular performance is by increasing heart rate. Dobutamine affects blood pressure minimally.     

Rescue sedation with dexmedetomidine for diagnostic imaging: a preliminary report

BACKGROUND: Sedation is frequently required during noninvasive radiological imaging in children. Although commonly used agents such as chloral hydrate and midazolam are generally effective, failures may occur. The authors report their experience with dexmedetomidine for rescue sedation during magnetic resonance imaging. METHODS: A retrospective chart review was undertaken. RESULTS: The cohort included five patients ranging in age from 11 months to 16 years. Following the failure of other agents (chloral hydrate and/or midazolam), dexmedetomidine was administered as a loading dose of 0.3-1.0 microg x kg(-1) x min(-1) over 5-10 min followed by an infusion of 0.5-1.0 microg x kg(-1) x h(-1). The dexmedetomidine loading dose required to induce sedation was 0.78 +/- 0.42 microg x kg(-1) (range 0.3-1.2). The maintenance infusion rate was 0.57 +/- 0.06 microg x kg(-1) x h(-1) (range 0.48-0.69). The imaging procedures were completed without difficulty. No patient required additional bolus administrations or changes in the infusion rate. The duration of the dexmedetomidine infusion ranged from 30 to 50 min. The mean decrease in heart rate was 13.6 +/- 5.1 b x min(-1) (14.3 +/- 5.0% from baseline; P = 0.02), the mean decrease in systolic blood pressure was 26.4 +/- 15.2 mmHg (24.6 +/- 12.4% decrease from baseline; P = 0.004), and the mean decrease in respiratory rate was 1.4 +/- 1.5 min(-1) (7.5 +/- 7.9% decrease from baseline; P = NS). P(E)CO2 exceeded 6.5 kPa (50 mmHg) in one patient [maximum 6.6 kPa (51 mmHg)] with a maximum value of 6.0 +/- 0.4 kPa (46 +/- 3 mmHg). Oxygen saturation decreased from 98 +/- 1 to 95 +/- 1%; P = 0.001. No patient developed hypoxemia (oxygen saturation less than 90%). Mean time to recovery to baseline status was 112.5 +/- 50.6 min and time to discharge was 173.8 +/- 83.8 min. CONCLUSIONS: Our preliminary experience suggests that dexmedetomidine may be an effective agent for procedural sedation during radiological imaging. Its potential application in this setting is discussed and other reports regarding its use in pediatric patients are reviewed.     

Dose-response relationship and infusion requirement of cisatracurium besylate in infants and children during nitrous oxide-narcotic anesthesia

BACKGROUND: To determine the effect of age on the dose-response relation and infusion requirement of cisatracurium besylate in pediatric patients, 32 infants (mean age, 0.7 yr; range, 0.3-1.0 yr) and 32 children (mean age, 4.9 yr; range, 3.1-9.6 yr) were studied during thiopentone-nitrous oxideoxygen-narcotic anesthesia. METHODS: Potency was determined using a single-dose (20, 26, 33, or 40 microg/kg) technique. Neuromuscular block was assessed by monitoring the electromyographic response of the adductor pollicis to supramaximal train-of-four stimulation of the ulnar nerve at 2 Hz. RESULTS: Least-squares linear regression analysis of the log-probit transformation of dose and maximal response yielded median effective dose (ED50) and 95% effective dose (ED95) values for infants (29+/-3 microg/kg and 43+/-9 microg/kg, respectively) that were similar to those for children (29+/-2 microg/kg and 47+/-7 microg/kg, respectively). The mean infusion rate necessary to maintain 90-99% neuromuscular block during the first hour in infants (1.9+/-0.4 microg x kg(-1) x min(-1); range: 1.3-2.5 microg x kg(-1) x min(-1)) was similar to that in children (2.0+/-0.5 microg x kg(-1) x min(-1); range: 1.3-2.9 microg x kg(-1) x min(-1)). CONCLUSION: The authors conclude that cisatracurium is equipotent in infants and children when dose is referenced to body weight during balanced anesthesia.     

Initial experience with dexmedetomidine for diagnostic and interventional cardiac catheterization in children

BACKGROUND: Children undergoing diagnostic and interventional cardiac catheterization require deep sedation or general anesthesia (GA). Dexmedetomidine, a selective alpha-2 adrenergic agonist, has sedative, analgesic and anxiolytic properties without respiratory depression. These characteristics make it potentially suitable as a sedative agent during diagnostic procedures in children. We report our experience using dexmedetomidine in 20 children aged 3 months to 10 years undergoing cardiac catheterization. METHODS: Following a midazolam premedication, intravenous access was secured facilitated by the inhalation of sevoflurane in oxygen. A loading dose of 1 microg x kg(-1) dexmedetomidine was administered over 10 min followed by an initial infusion rate of 1 microg x kg(-1) x h(-1). Nasal cannulae were applied, allowing endtidal CO2 monitoring with the patients breathing spontaneously. Hemodynamic parameters, Bispectral Index Score (BIS) and sedation score were measured every 5 min. Patient movement or evidence of inadequate sedation were treated with propofol (1 mg x kg(-1)). The dexmedetomidine infusion rate was titrated to the level of sedation to a maximum of 2 microg x kg(-1) x h(-1) to maintain a sedation score of 4-5 and a BIS value <80. RESULTS: Five patients (25%) had some movement on local infiltration or groin vessel access. This did not necessitate restraint or result in difficulty securing vascular access. No patients failed sedation that required the addition of another sedative agent or conversion to GA; eight patients were sedated with dexmedetomidine alone; however, 12 (60%) patients did receive a propofol bolus at some time during the procedure due to movement, increasing BIS value or in anticipation of stimulation. There were no incidences of airway obstruction or respiratory depression. In all cases the heart rate and blood pressure remained within 20% of baseline. No patient required treatment for profound bradycardia or hypotension. The average infusion rate for dexmedetomidine following the loading dose was 1.15 (+/-0.29)microg x kg(-1) x h(-1) (range 0.6-2.0 microg x kg(-1) x h(-1)). CONCLUSIONS: This initial experience showed dexmedetomidine, with or without the addition of propofol, may be a suitable alternative for sedation in spontaneously breathing patients undergoing cardiac catheterization.     

The efficacy of preemptive Milrinone or Amrinone therapy in patients undergoing coronary artery bypass grafting.

Acute deterioration in ventricular function and oxygen transport is common after cardiac surgery. We hypothesized that milrinone or amrinone may reduce their occurrence and catecholamine requirements and increase cellular enzyme levels in patients undergoing coronary artery bypass. In 45 patients, we randomly administered milrinone 50 microg/kg plus 0.5 microg x kg(-1) x min(-1) infusion for 10 h, amrinone 1.5 mg/kg plus 10 microg x kg(-1) x min(-1) infusion for 10 h, or placebo at release of aortic cross-clamp. Hemodynamic variables, dopamine requirement, and laboratory values were recorded. At the postoperative nadir, stroke volume index was higher in the Milrinone and Amrinone groups (mean +/- SD, 27.8 +/- 4.0 and 26.1 +/- 3.2 vs. 20.4 +/- 5.1 mL x min (-1) x m(-2) per beat, P < 0.0001), and oxygen transport index was higher (354.7 +/- 57.8 and 353.7 +/- 91.2 vs 283.0 +/- 83.9 mL. min(-1) x m(-2), P = 0.009). The postoperative dopamine requirement was less (6.6 +/- 2.7 and 6.8 +/- 2.6 vs 10.4 +/- 2.0 mg/kg, P < 0.008), and postoperative serum lactate, alanine and aspartate aminotransferase, lactate dehydrogenase, creatinine kinase, C-reactive protein, and glucose levels were less (P < 0.01). The mean postoperative heart rate was faster in the Milrinone group than in the Amrinone and Placebo groups (96.8 +/- 10.3 vs. 86.9 +/- 9.5 and 87.8 +/- 10.8 bpm, P < 0.01). Milrinone and amrinone administered preemptively reduce postoperative deterioration in cardiac function and oxygen transport, dopamine requirement, and increases in serum lactate, glucose, and enzyme levels, although milrinone may increase heart rate. IMPLICATIONS: Preemptive milrinone or amrinone administration before separation from cardiopulmonary bypass in cardiac surgical patients not only ameliorates postoperative deterioration in cardiac function and oxygen transport, but also reduces dopamine requirement and increases serum lactate, glucose, and cellular enzyme levels, although milrinone may increase heart rate.     

Remifentanil provides better protection against noxious stimuli during cardiac surgery than alfentanil

BACKGROUND AND OBJECTIVE: We hypothesized that remifentanil-propofol cardiac anaesthesia, plus administration of pirinitramide (piritramide) upon cessation of the remifentanil infusion, would be associated with a shorter time to tracheal extubation than alfentanil-propofol anaesthesia, without the occurrence of major haemodynamic instability. METHODS: Haemodynamic stability and recovery characteristics of two remifentanil infusion regimens (0.5 microg kg(-1)min(-1); 0.25 microg kg(-1)min(-1)) were therefore compared with an alfentanil infusion regimen (1 microg kg(-1)min(-1)), in combination with target-controlled infusion of propofol, in a randomized blinded trial in 75 coronary artery surgery patients. RESULTS: Pirinitramide provided good postoperative analgesia without prolonging extubation times: median extubation time in minutes after stopping the opioid-sedative drugs was 300 in the higher-dose remifentanil group and 270 in the lower-dose remifentanil group and alfentanil group (P = 0.606). Significant time-by-treatment interactions were seen for systolic arterial pressure (P = 0.015), mean arterial pressure (P = 0.009) and diastolic arterial pressure (P = 0.006). No significant interaction (P = 0.489) and no constant treatment effect were seen for heart rate (P = 0.288). Time effects were highly significant (P < 0.0001) for all haemodynamic variables. Heart rate remained stable in all groups. In the higher-dose remifentanil group, blood pressure was significantly different and lower during surgery and in this group less bolus doses of the opioid-sedative drugs (P = 0.015) had to be given. CONCLUSION: The higher-dose remifentanil infusion provided superior suppression of haemodynamic responses to noxious stimuli with better haemodynamic stability.     

Oral clonidine reduces the requirement of prostaglandin El for induced hypotension

PURPOSE: To determine the effects of preanesthetic oral clonidine on the dose of prostaglandin EI (PGEI) required to produce hypotension during anesthesia. METHOD: Oral placebo, 75 microg or 150 microg clonidine were administered 60 min prior to induction of anesthesia. Anesthesia was maintained with O2:N2O (30:70) and isoflurane 1.0%. After hemodynamic stabilization, an infusion of prostaglandin EI was started (0.05 microg x kg(-1) x min(-1)) and the rate of infusion was adjusted to maintain mean arterial pressure (MAP) between 60-70 mm Hg during operation. RESULTS: Duration of hypotension in placebo, 75 microg and 150 microg preanesthetic oral clonidine treated groups were 132+/-46, 117+/-37 and 129+/-56 min, respectively. The PGEI requirement in each group were 1563+/-180 (28.6+/-3.2), 594+/-197 (10.8+/-3.6) and 283+/-30 (5.5+/-3.6) microg (microg x kg(-1)), respectively. In addition, blood loss in each group were 1461+/-389, 805+/-240 and 931+/-40 ml, respectively. CONCLUSION: Preanesthetic oral clonidine decreased the dose of PGEI required to produce hypotension, and decreased the blood loss during operation.     

Total intravenous anesthesia with remifentanil, propofol and cisatracurium in end-stage renal failure

PURPOSE: To compare recovery parameters of total intravenous anesthesia (TIVA) with remifentanil and propofol, hemodynamic responses to perioperative events, and pharmacodynamic parameters of cisatracurium in 22 end-stage renal failure and 22 normal renal function patients. METHODS: Anesthesia was induced with 2-3 mg x kg(-1) propofol and 1 microg x kg(-1) remifentanil and maintained with 75 microg x kg(-1) x min(-1) propofol and propofol initial infusion of 0.2 microg x kg(-1) x min(-1) propofol. Arterial pressure and heart rate were maintained by remifentanil infusion rate adjustments. The first twitch (T1) was maintained at 25% by an infusion of cisatracurium. RESULTS: There was no difference in the time to maintenance of adequate respiration, date of birth recollection, first analgesic administration, between the renal failure (4.8+/-2.5, 7.8+/-3.2, 12.3+/-5.3 min respectively) and the control group (5.2+/-2.8, 8.1+/-3.1, 12.7+/-5.5 min): nor were there any differences in the time to 25% T1 recovery, T1 recovery from 25% to 75%, or cisatracurium infusion rate between the renal failure group (32.1 +/-10.8 min, 18.2+/-5.5 min, 0.89+/-0.29 microg x kg(-1) min(-1) respectively) and the control group (35.9 (7.9 min, 18.4+/-3.8 min, 0.95+/-0.22 microg x kg(-1) x min(-1)). CONCLUSION: End-stage renal failure does not prolong recovery from TIVA with remifentanil and propofol, or the recovery from cisatracurium neuromuscular block.     

Effects of remifentanil and fentanyl on intraocular pressure during the maintenance and recovery of anaesthesia in patients undergoing non-ophthalmic surgery

BACKGROUND AND OBJECTIVE: To compare the effects of remifentanil and fentanyl on intraocular pressure during the maintenance and recovery of anaesthesia in patients undergoing elective non-ophthalmic surgery. METHODS: Thirty-two patients (ASA I-II) were randomized into two groups to receive either a continuous infusion of remifentanil (0.25-0.5 microg kg(-1) min(-1), n =16, Group R) or an intermittent bolus of fentanyl (2-5 microg kg(-1), n = 16, Group F) during the maintenance of anaesthesia. For the induction of anaesthesia, Group R received remifentanil 1 microg kg(-1) and Group F received fentanyl 2 microg kg(-1); both groups then received propofol 2 mg kg(-1) with vecuronium 0.1 mg kg(-1). Anaesthesia in both groups was maintained with a continuous infusion of propofol 4-8 mg kg(-1) h(-1). Ventilation of the lungs was controlled to a constant end-tidal PCO2 of 4.7-5.4 kPa. Blood pressure, electrocardiography, heart rate and oxygen saturation were monitored throughout anaesthesia. Intraocular pressure was determined before surgery, during the maintenance of anaesthesia, 2 min after emergence and in the recovery room using a Perkins hand-held applanation tonometer by an ophthalmologist blinded to the anaesthetic technique. RESULTS: After induction of anaesthesia, a significant decrease in intraocular pressure in the remifentanil group from 13.6 +/- 2.6 to 7.1 +/- 3.1 mmHg (P < 0.001) and in the fentanyl group from 13.7 +/- 2.2 to 9.7 +/- 3.4 mmHg (P < 0.001) was observed and maintained during anaesthesia. Thirty minutes after the end of anaesthesia, intraocular pressure returned to baseline values in both groups (remifentanil: 13.9 +/- 2.8 mmHg, P = 0.28; fentanyl: 13.6 +/- 2.3 mmHg, P = 0.59). The intraocular pressure and haemodynamic variables did not differ significantly between the two groups (intraocular pressure, P = 0.7327; blood pressure, P = 0.1295; heart rate, P = 0.8601). CONCLUSIONS: Remifentanil maintains intraocular pressure at an equally reduced level compared with fentanyl.     

Cardiac anesthesia induction by low target plasma concentration setting of propofol using target-controlled infusion

BACKGROUND: Propofol-anesthesia administerd using target-controlled infusion (TCI) has been proposed for cardiac surgery. But, moderate target concentration of propofol during induction using TCI has not been studied in detail. METHODS: Thirty patients scheduled for cardiac surgery under cardiopulmonary bypass (CPB) and TCI propofol anesthesia were randomly divided into two groups to receive a computer-controlled infusion of propofol with target concentrations of 1.5 or 2.0 micro/g x ml(-1) [1.5 microg x ml(-1) group (n=15) and 2.0 microg x ml(-1) group (n=15)]. Mean arterial pressure (MAP), heart rate (HR) and bispectral index scale (BIS) values were recorded at 5 time points during induction of anesthesia. RESULTS: MAP was significantly lower in 2.0 microg x ml(-1) group compared with 1.5 microg x ml(-1) group. In both groups, a rise of BIS value did not occur during tracheal intubation. CONCLUSIONS: We have demonstrated that propofol TCI at a target concentration of 1.5 microg x ml(-1) is effective for hemodynamic stability during induction of anesthesia in patients for cardiac surgery under CPB.