Comparisons of the segments of left-sided double-lumen tracheobronchial tubes as industrial products.

BACKGROUND: Although there are at least seven manufacturers producing left-sided double-lumen tubes (DLTs), there have been few reports comparing the segments of these DLTs. In this study, we compared various segments of left-sided DLTs further. MATERIALS AND METHODS: We examined five manufacturers' left-sided DLTs: Mallinckrodt, Portex, Rüsch, Sheridan, and Daiken-medical. We conducted the following six trials or measurements, and three supplemental trials or measurements: First, we tried to pass various sizes of steel balls down each lumen in order from the smallest (3 mm) to largest (4.5 mm). If the ball passed on the first attempt, we tried just once; otherwise, we made a second attempt. Second, we measured the external diameter of tracheal and bronchial cuff using a profile projector. Third, we measured the length of the cuff and tip of the bronchial segment of the tubes using the profile projector. Fourth, we measured various lengths of the tubes. Fifth, we measured the external diameter of both lumens and the tubules for tracheal and bronchial cuff inflation. Finally, we measured various cross-sectional areas including the tracheal lumen, bronchial lumen, and tubules for cuff inflation. We also conducted three supplemental studies. First, we measured air volume in the cuff when intracuff pressure equaled 2 or 3 kPa. Second, we defined the configuration of the tracheal and bronchial cuffs. Third, we defined the presence or absence of bevels and also measured the angle of the bevels using the profile projector. RESULTS: We performed nine trials and measurements and found large disparities between each manufacturer's tubes. CONCLUSIONS: The large disparities found between the measurements of the five manufacturers' tubes may be due to different lots or changes in specifications made by each manufacturer. We found tubes exhibiting lower quality, such as deformations, and non-universal and inconsistent sizing, in the comparison of the manufacturers' tubes. Practitioners should be aware of the features and aspects of these tubes.

Bolus administration of ephedrine and etilefrine induces transient vasodilation just after injection in combined epidural and general anesthesia patients: A randomized clinical study.

Hypotension commonly accompanies combined epidural and general anesthesia, and intravenous bolus ephedrine and etilefrine are widely used to correct hypotension. We have noticed that systemic vascular resistance (SVR) transiently decreases just after intravenous bolus administration of these drugs. The goal of the present study was to investigate whether bolus administration of these drugs decrease SVR just after intravenous administration in combined epidural and general anesthesia patients. We investigated 40 patients who were scheduled for elective abdominal surgery. Patients were chosen as subjects if their systolic arterial pressure decreased by 20% or to <100 mmHg at 30 min after the induction of general anesthesia. Baseline hemodynamic values were recorded, and after ephedrine 10 mg injection or etilefrine 2 mg injection (equipotent), the parameters were recorded again at 0.5 min and once each min for the next 5 min thereafter. The 40 patients were enrolled into the ephedrine (n = 20) or etilefrine (n = 20) treatment groups. Patient characteristics were comparable in both groups. After ephedrine injection, SVR decreased significantly at the 1-min time point, whereas after etilefrine injection, SVR decreased significantly at the 0.5- to 2-min time points compared with baseline values. SVR at the 0.5- to 1-min time points was lower in the etilefrine versus the ephedrine group. Both drugs transiently decreased SVR after intravenous injection, but etilefrine decreased SVR much more than ephedrine, indicating that more vasodilation occurred after the injection of etilefrine than after ephedrine. It is thus important to recognize the different characteristics of these drugs.

Does pneumoperitoneum affect perfusion index and pleth variability index in patients receiving combined epidural and general anesthesia?

Plethysmographic variability index (PVI) is a dynamic index used for the purpose of fluid responsiveness in patients, and the effect of pneumoperitoneum on PVI is still unclear. We therefore attempted to determine whether PVI and perfusion index (PI) change before/after pneumoperitoneum in patients receiving combined epidural and general anesthesia, which is a common anesthesia method with intravenous remifentanil. Twenty patients underwent laparoscopic cholecystectomy or colectomy. Immediately before pneumoperitoneum, variables were measured at baseline I and were then measured every min for 5 min after pneumoperitoneum start. Immediately before pneumoperitoneum release, variables were measured at baseline II and were measured every min for 5 min after pneumoperitoneum release. Compared with baseline I values, after pneumoperitoneum start, significant increases occurred in stroke volume variation (SVV) at 1-5 min, and significant decreases occurred in PI at 1-5 min. PVI did not change. Compared with baseline II values, after pneumoperitoneum release, significant increases occurred in PI at 1-5 min, and significant decreases occurred in PVI at 4-5 min and SVV at 1-5 min. In patients receiving combined epidural and general anesthesia, we newly found that PI decreased but PVI remained unchanged with a sufficient dose of remifentanil and epidural anesthesia that can block noxious stimuli and also most sympathetic activity. Furthermore, we reconfirmed that PI increased and PVI decreased upon release of pneumoperitoneum. PI and PVI values must be estimated cautiously during and after pneumoperitoneum.

Does intravenous atropine affect stroke volume variation in man?

OBJECTIVES: Currently there are no reports of the effect of increasing heart rate (HR) induced by intravenous atropine on stroke volume variation (SVV). We hypothesized that increasing HR alters the value of SVV. This prospective study aimed to investigate changes in SVV values by increasing HR induced by intravenous atropine in patients with good cardiac function. We also re-evaluated the effect of intravenous atropine alone on hemodynamics including new hemodynamic parameters such as SVV. METHODS: Patients were chosen as participants of this study if, 30 minutes after anesthesia induction, HR was below 65 beats/min. Baseline hemodynamic values were recorded, and then the patients received intravenous atropine (0.01 mg/kg; max 0.5 mg). These values were recorded again after intravenous atropine every minute for 5 minutes. RESULTS: Ten American Society of Anesthesiologists (ASA) physical status I-II patients aged 37-65 years who were scheduled for elective surgery were included. Intravenous atropine significantly increased HR at the 1-5 minute time points, mean arterial pressure at the 1-4 minute time points, and cardiac output at the 1-3 minute time points compared with baseline values but did not significantly change SVV, stroke volume index, pressure of end-tidal CO2, and systemic vascular resistance. CONCLUSION: Administration of intravenous atropine did not change SVV, and we present this as a novel finding.

Pneumoperitoneum affects stroke volume variation in humans.

PURPOSE: Stroke volume variation (SVV) is affected by many factors. Although elevated intra-abdominal pressure and a pneumoperitoneum have been shown to increase SVV in animals, a recent human study showed that SVV did not change as a pneumoperitoneum was established. However, we considered the results of this study questionable, and we therefore attempted to study whether SVV changes both before and after pneumoperitoneums in humans. METHODS: We performed a prospective observational study in 19 patients undergoing cholecystectomy or colectomy while on mechanical ventilation. Immediately before pneumoperitoneum, baseline registrations of variables were obtained (baseline I), which were measured every min for 5 min after the pneumoperitoneum was initiated. Immediately before the pneumoperitoneum was released, another baseline registration of variables was obtained (baseline II); these variables were then measured every min for 5 min. RESULTS: After the pneumoperitoneum was initiated, there were significant increases in SVV at the 2- to 5-min time points. After release of the pneumoperitoneum, there were significant decreases in SVV at the 1- to 5-min time points. CONCLUSION: A pneumoperitoneum increased SVV, which is similar to the findings of previous animal studies but is different from a previous clinical study. Upon release of the pneumoperitoneum, SVV decreased significantly, which is new information. SVV values must be estimated cautiously during a pneumoperitoneum.

Does intravenous landiolol, a ß1-adrenergic blocker, affect stroke volume variation?

PURPOSE: There are no reports about the effect of bradycardia on stroke volume variation (SVV), and we hypothesized that induced bradycardia alters the value of SVV. Landiolol, an ultra-short-acting adrenergic ß1-receptor blocking agent, was reported to induce bradycardia without decreasing blood pressure. The initial aim of this prospective study was to investigate changes in SVV values by induced bradycardia in patients with good cardiac function. METHODS: At 30 min after anesthesia induction, if heart rate (HR) was >80 bpm, the patient was chosen as a subject. Ten ASA physical status I-II patients aged 38-75 years who were scheduled for elective abdominal surgery were included in this study. Baseline values were recorded, and then administration of landiolol was started at 125 µg/kg/min for 1 min and then continued at 40 µg/kg/min. SVV and other parameters were recorded at baseline and 3 min after continuous landiolol injection. RESULTS: Landiolol significantly decreased systolic arterial pressure, and diastolic arterial pressure, contrary to our expectations, and also HR, SVV, cardiac output, stroke volume index, and pressure of end-tidal CO(2), whereas systemic vascular resistance values increased significantly. CONCLUSIONS: SVV decreased after continuous administration of a ß1-adrenergic blocker, probably because of a decrease in the difference of maximum stroke volume (SV) and minimum SV, or the downward shift of the Frank-Starling curve that occurred after landiolol administration. We believe that SVV values might be overestimated or misinterpreted when HR is decreased by landiolol and might not necessarily indicate that the patient is hypervolemic or normovolemic.

Vigilance of hemodynamic changes immediately after transferring patients is crucial.

PURPOSE: A decrease in blood pressure is sometimes observed when a postsurgical patient is transferred to another bed after recovering from anesthesia. However, the mechanism behind this hypotension has not been completely elucidated. The purpose of this study was to investigate and compare changes in hemodynamic properties for possible causes of hypotension before and after transfer to another bed of postsurgical patients receiving general anesthesia, combined epidural and general anesthesia, or combined spinal and general anesthesia. METHODS: We studied 69 patients undergoing elective surgery who were randomized to receive anesthesia by one of the three methods. After surgery, the tracheal tube was removed, and each patient was transferred to another bed. Hemodynamic data recorded immediately before and after transfer of the patient to another bed were compared. RESULTS: After transfer of patients receiving general anesthesia or combined epidural and general anesthesia, systolic arterial pressure (SAP), diastolic arterial pressure (DAP), and cardiac output (CO) decreased; heart rate (HR) and systemic vascular resistance (SVR) did not change. However, after transfer of patients receiving combined spinal and general anesthesia, SAP, DAP, HR, and CO decreased, but SVR did not change. CONCLUSION: The decrease in blood pressure observed after transfer of a postsurgical patient to another bed after general, combined epidural and general, and combined spinal and general anesthesia was associated with a decrease in CO and no change in SVR, but HR decreased after combined spinal and general anesthesia, whereas it was unchanged after general and combined epidural and general anesthesia. The decrease in blood pressure is assumed to be caused by a decrease in venous return, and several reflexes might participate in this decrease of blood pressure, especially after combined spinal and general anesthesia.

Do induced hypertension and hypotension affect stroke volume variation in man?

STUDY OBJECTIVE: To investigate changes in stroke volume variation (SVV) by both induced hypertension (pressor test) and hypotension (depressor test), and also by induced hypotensive anesthesia in patients with good cardiac function. DESIGN: Prospective, controlled clinical study. SETTING: University hospital. PATIENTS: 31 ASA physical status 1 and 2 patients, aged 39-62 years, who were scheduled for elective surgery. INTERVENTIONS: We conducted three studies: a pressor test study, a depressor test study, and an induced hypotensive anesthesia study. In the pressor test, patients received a bolus of phenylephrine 0.001 mg/kg to increase systolic arterial pressure (SAP) by 30% to 40% compared with baseline. In the depressor test, patients received a bolus of nitroglycerine 0.005 mg/kg to decrease SAP by 30% to 40% compared with baseline. In the induced hypotensive anesthesia test, patients received intravenous (IV) nitroglycerine continuously until mean arterial pressure (MAP) was reduced to 60-70 mmHg. MEASUREMENTS: When arterial pressure reached the target pressure for each study type, SVV and other parameters were recorded. MAIN RESULTS: Induced hypertension (pressor test) decreased SVV, while induced hypotension (depressor test) and induced hypotensive anesthesia increased SVV. CONCLUSIONS: SVV does not misinterpret preload dependency assessment of patients receiving medications to increase or to lower blood pressure.

Intravenous landiolol, a novel ß(1)-adrenergic blocker, reduces the minimum alveolar concentration of sevoflurane in women.

STUDY OBJECTIVE: To investigate the effect of intravenous (IV) landiolol, a novel ß(1)-adrenergic blocker, on the minimum alveolar concentration (MAC) of sevoflurane in adult women. DESIGN: Prospective, randomized study. SETTING: University hospital. PATIENTS: 42 ASA physical status 1 and 2 women, aged 24-57 years, who were scheduled to undergo elective abdominal surgery. INTERVENTIONS: Anesthesia was induced in all patients by vital capacity rapid inhalation induction of sevoflurane. In the landiolol group, administration of landiolol began when patients took a vital-capacity breath: 0.125 mg/kg/min for one minute and then 0.04 mg/kg/min. Normal saline was administered in the control group. MEASUREMENTS: MAC was determined by a technique adapted from the conventional up-down method. MAIN RESULTS: The MAC of sevoflurane was 2.2% ± 0.2% in the control group and 1.7% ± 0.2% in the landiolol group, a statistically significant difference (P = 0.0005). CONCLUSIONS: IV landiolol reduces the MAC of sevoflurane in women by approximately 20%.

Assessment of the effect of rapid crystalloid infusion on stroke volume variation and pleth variability index after a preoperative fast.

OBJECTIVE: Stroke volume variation (SVV) during controlled mechanical ventilation is a useful predictor in response to volume expansion, and pleth variability index (PVI), a novel algorithm allowing for automated and continuous calculation of the respiratory variations in the pulse oximeter waveform amplitude, can also predict fluid responsiveness non-invasively in mechanically ventilated patients. The aim of this study was (1) to determine whether acute fluid infusion affects SVV and PVI, and (2) to compare the two values in the case of acute fluid infusion after a preoperative fast following general anesthesia induction. METHODS: After tracheal intubation, the patients' lungs were mechanically ventilated. Subjects were anesthetized using sevoflurane and were given a rapid, constant-rate infusion of crystalloid (500 ml in 15 min). Systolic arterial pressure (SAP), diastolic arterial pressure (DAP), heart rate (HR), cardiac output (CO), cardiac index (CI), SVV, and PVI were measured at baseline and after 250 and 500 ml had been infused, and these values were compared. RESULTS: SAP, DAP, CO, and CI were unchanged after the infusion. HR and SVV decreased significantly after the infusion. SVI increased significantly after the infusion. There was a significant difference in PVI only between the post 250 ml and post 500 ml infusions. CONCLUSIONS: A rapid infusion of 250-500 ml of a crystalloid in nearly healthy subjects who had fasted overnight returned their SVV to within the normal range. In such cases, SVV is a more sensitive predictor of fluid responsiveness than is PVI, and the infusion gradually increased SVI.

Prophylactic continuous administration of landiolol, a novel ß1 blocker, blunts hyperdynamic responses during electroconvulsive therapy without altering seizure activity.

Abstract Objective. In previous reports, it has been shown that many drugs may act against hyperdynamic responses during electro-convulsive therapy (ECT). The aim of this study was to conduct a randomized, placebo-controlled crossover study to investigate the hemodynamic responses and seizure duration during ECT by continuous administration of two doses of landiolol, a novel short-acting ß1-adrenergic blocker, including standard and high-dose. Methods. Thirty-two patients undergoing ECT participated in this study. The control treatment was infusion of saline alone. The standard-dose of landiolol, 0.125 mg/kg per min, was infused over a 1-min period as a standard treatment. The high-dose landiolol treatment was 0.25 mg/kg per min, also infused over a 1-min period. After landiolol treatments, patients received landiolol at 0.04 mg/kg per min. Propofol and succinylcholine was then administered, and electrical stimulation was applied. Results. Both peak heart rate and mean arterial pressure after ECT was lowest with high-dose landiolol treatment. Motor and EEG seizure duration did not differ among the treatments. Conclusion. The results of this study show that high-dose landiolol treatment blunts hyperdynamic responses during ECT. Furthermore, landiolol does not reduce the seizure duration.

Effect of oral tizanidine on local-anesthetic infiltration pain during epidural catheterization.

PURPOSE: Tizanidine is a clonidine derivative and has the same effects, such as sedation, anxiolysis and analgesic response. We evaluated the effect of tizanidine on infiltration pain during epidural catheterization. METHODS: Forty patients scheduled to undergo epidural anesthesia in elective surgery were randomly allocated into two groups. The control group received placebo 60 minutes before arrival in the operating room, and the tizanidine group received 3 mg of oral tizanidine as premedication 60 minutes before arrival in the operating room. Every patient was measured heart rate and blood pressure before receiving placebo or premedication and after arrival in the operating room. After an epidural catheter was indwelled, the patients were questioned about the infiltrating pain of local anesthetic, and the degree was assessed by means of visual analog scale score (VAS score, 0 to approximately 100 mm). RESULTS: Blood pressure in the operating room was significantly attenuated in the tizanidine group compared to the control group (148 +/- 21 mmHg vs 130 +/- 15 mmHg). Heart rate was not significantly different between the two groups. Rate-pressure product was significantly lower in the tizanidine group (11282 +/- 2960 vs 9592 +/- 2632). VAS score in the tizanidine group was significantly lower than that in the control group (P <0.001). CONCLUSION: It was possible to reduce the infiltration pain of local anesthetic during epidural catheterization by oral administration of 3 mg of tizanidine as premedication. Blood pressure and rate-pressure product in the operating room were also attenuated by receiving tizanidine. Therefore, we recommend premedication with tizanidine for patients undergoing epidural catheterization.

Intravenous alprostadil, an analog of prostaglandin E1, prevents thiamylal-fentanyl-induced bronchoconstriction in humans.

UNLABELLED: Prostaglandin (PG) E(1) relaxes airway smooth muscle in animals. However, no clinical data have been published on the bronchorelaxant effects of IV alprostadil, an analog of PGE(1). We have described experimental thiamylal-fentanyl-induced bronchoconstriction in humans; we now report the effect of IV alprostadil on thiamylal-fentanyl-induced bronchoconstriction. Thirty-two patients were allocated randomly to a control group (n = 16) and alprostadil group (n = 16). Anesthesia was induced with thiamylal 5 mg/kg and vecuronium 0.3 mg/kg and maintained with a continuous infusion of thiamylal 15 mg. kg(-1). h(-1). The lungs of the patients were ventilated with 50% nitrous oxide in oxygen. Twenty minutes after the induction of anesthesia, patients in the control group were given a continuous infusion of normal saline 20 mL/h, and those in the alprostadil group received a continuous infusion of alprostadil 0.2 micro g. kg(-1). min(-1) (20 mL/h), both for 60 min. Both groups were then given fentanyl 5 micro g/kg. Systolic and diastolic arterial blood pressure, heart rate, mean airway resistance (Rawm), expiratory airway resistance (Rawe), and dynamic lung compliance (Cdyn) were measured at the baseline, just before the fentanyl injection (T30), at three consecutive 6-min intervals after fentanyl injection (T36, T42, and T48), and 30 min after fentanyl injection (T60). Baseline Rawm, Rawe, and Cdyn values were comparable between groups. In the control group, both Rawm and Rawe were significantly increased at T36-60, and Cdyn was significantly decreased at T36-60 compared with the baseline. Patients given alprostadil showed no change in Rawm, Rawe, or Cdyn at T36-60. Thus, IV alprostadil seems to have a bronchodilator effect in humans. IMPLICATIONS: IV alprostadil, an analog of prostaglandin E(1), prevents thiamylal-fentanyl-induced bronchoconstriction in humans. This finding suggests that IV alprostadil has a bronchodilator effect.

Effect of prophylactic bronchodilator treatment with intravenous colforsin daropate, a water-soluble forskolin derivative, on airway resistance after tracheal intubation.

BACKGROUND: After induction of anesthesia, lung resistance increases. The authors hypothesized that prophylactic bronchodilator treatment with intravenous colforsin daropate, a water-soluble forskolin derivative, before tracheal intubation would result in decreased lung resistance and increased lung compliance after tracheal intubation when compared with placebo medication. METHODS: Forty-six adult patients were randomized to placebo or colforsin daropate treatment. Patients in the control group received normal saline; patients in the colforsin group received 0.75 microg. kg-1 x min-1 colforsin daropate intravenously until the study ended. Thirty minutes after the study began, the authors administered 5 mg/kg thiamylal and 5 microg/kg fentanyl for induction of general anesthesia and 0.3 mg/kg vecuronium for muscle relaxation. A 15-mg. kg-1. h-1 continuous infusion of thiamylal followed anesthetic induction. Four, 8, 12, and 16 min after tracheal intubation, mean airway resistance (R(awm)), expiratory airway resistance (R(awe)), and dynamic lung compliance (C(dyn)) were measured. RESULTS: Patients in the colforsin group had significantly lower R(awm) and R(awe) and higher C(dyn) after intubation than those in the control group. Differences in R(awm), R(awe), and C(dyn) between the two groups persisted through the final measurement at 16 min. At 4 min after intubation, smokers had a higher R(awm) and a lower C(dyn) than nonsmokers in the control group. After treatment by intravenous colforsin daropate, R(awm), R(awe), and C(dyn) values were similar for smokers and nonsmokers after tracheal intubation. CONCLUSIONS: Prophylactic treatment with colforsin daropate produced lower R(awm) and R(awe) and higher C(dyn) after tracheal intubation when compared with placebo medication. Pretreatment before intubation may be beneficial and advantageous for middle-aged smokers.

Intravenous nicorandil prevents thiamylal-fentanyl-induced bronchoconstriction in humans.

OBJECTIVE: Nicorandil has a hybrid property between nitrates and potassium channel openers and has been reported to cause a concentration-dependent relaxation of isolated guinea pig trachealis. Experimental asthma in a guinea pig model was also inhibited by nicorandil. However, no clinical data on the bronchorelaxant effects of this drug have been published. The aim of this study was to investigate whether intravenous nicorandil prevents thiamylal-fentanyl-induced bronchoconstriction. DESIGN: Double-blind, prospective, placebo-controlled, randomized study. PATIENTS: A total of 36 patients were randomly allocated to two groups: a control group (n = 18) and a nicorandil group (n = 18). INTERVENTIONS: Intravenous administration of nicorandil or a placebo (normal saline). MEASUREMENTS AND MAIN RESULTS: Anesthesia was induced with 5 mg/kg thiamylal and 0.3 mg/kg vecuronium. A continuous infusion of 15 mg x kg(-1) x hr(-1) thiamylal was then used to maintain the anesthesia. Controlled ventilation was maintained, delivering 50% nitrous oxide in oxygen. At 20 mins after the induction of anesthesia, the control group patients were given a 6 mL/hr continuous infusion of normal saline and the nicorandil group patients were given a 6 mg x hr(-1) (6 mL/hr) continuous infusion of nicorandil for 60 mins. At 30 mins after the start of the study, both groups received a 5-microg/kg dose of fentanyl. Systolic and diastolic arterial pressure, heart rate, mean airway resistance, expiratory airway resistance, and dynamic lung compliance were measured for the baseline condition, just before the administration of fentanyl (T30), at three consecutive 6-min intervals after the fentanyl injection (T36, T42, and T48) and 30 mins after the fentanyl injection (T60). Both groups had comparable baseline values for mean airway resistance, expiratory airway resistance, and dynamic lung compliance. In the control group, both mean airway resistance and expiratory airway resistance increased significantly at T36-60, compared with the baseline values, and dynamic lung compliance decreased significantly at T36-60, compared with the baseline value. In the nicorandil group, no changes in mean airway resistance, expiratory airway resistance, or dynamic lung compliance occurred at T36-60. CONCLUSIONS: Our observations suggest that the intravenous administration of nicorandil has a bronchodilator effect in humans.

Oral tizanidine, an alpha2-adrenoceptor agonist, reduces the minimum alveolar concentration of sevoflurane in human adults.

UNLABELLED: Tizanidine, an alpha2-adrenoceptor agonist, has an antinociceptive effect in animals. In humans premedicated with oral tizanidine, the increase in blood pressure associated with laryngoscopy and intubation was attenuated, and the amount of midazolam required for loss of consciousness was significantly reduced. We speculated that the oral administration of tizanidine might reduce the minimum alveolar anesthetic concentration (MAC) of sevoflurane. Fifty-two ASA physical status I-II patients, aged 24-56 yr, were randomly allocated into two groups: a Control group (n = 26) and a Tizanidine group (n = 26). As premedication, the Control group received a placebo, and the Tizanidine group received 4 mg of oral tizanidine 90 min before surgical skin incision. Anesthesia was induced in all patients by using vital capacity rapid inhaled induction with sevoflurane (5%). Loss of consciousness was defined as both the loss of the eyelid reflex and the lack of a response to a verbal command. MAC was determined by a technique adapted from the conventional up-down method for quantal responses. The MAC of sevoflurane was 2.2% +/- 0.2% in the Control group and 1.8% +/- 0.2% in the Tizanidine group (P = 0.0004). The time to loss of consciousness in the Tizanidine group (60.2 +/- 22.5 s) was significantly shorter than that in the Control group (73.7 +/- 26.3 s) (P = 0.03). The oral administration of tizanidine 4 mg successfully reduced the MAC of sevoflurane by 18% in human adults. IMPLICATIONS: Oral tizanidine (4 mg), an alpha2-adrenoceptor agonist, reduces the minimum alveolar concentration of sevoflurane by 18%.

Intravenous verapamil blunts hyperdynamic responses during electroconvulsive therapy without altering seizure activity.

IMPLICATIONS: A dose of 0.1 mg/kg of verapamil, administered immediately before anesthesia, significantly reduces the increase in peak heart rate and mean arterial blood pressure after electroconvulsive therapy. Furthermore, the administration of verapamil does not reduce the duration of the seizure.

Intravenous colforsin daropate, a water-soluble forskolin derivative, prevents thiamylal-fentanyl-induced bronchoconstriction in humans.

OBJECTIVE: Forskolin, a direct activator of adenylate cyclase, can relax airway smooth muscle, similar to other agents that increase intracellular cyclic adenine monophosphate. However, the potential usefulness of forskolin in treating bronchospasm is limited by its poor water solubility. Colforsin daropate is a novel and potent water-soluble forskolin derivative. No clinical data have been published on the bronchorelaxant effects of this drug. The aim of this study was to investigate whether intravenous colforsin daropate prevents thiamylal-fentanyl-induced bronchoconstriction. DESIGN: Double-blind, prospective, placebo-controlled randomized study. SETTING: University teaching hospital. PATIENTS: Thirty-six patients were allocated randomly to two groups: the control group (n = 18) and colforsin daropate group (n = 18). INTERVENTIONS: Intravenous administration of colforsin daropate or placebo (normal saline). MEASUREMENTS AND MAIN RESULTS: Anesthesia was induced with thiamylal 5 mg/kg and vecuronium 0.3 mg/kg. A 15 mg x kg(-1) x hr(-1) continuous infusion of thiamylal followed anesthetic induction. Controlled ventilation was maintained, delivering 50% nitrous oxide in oxygen. Twenty minutes after the induction of anesthesia, the control group patients started to receive 7.5 mL/hr continuous infusion of normal saline, and the colforsin daropate group patients started to receive 0.75 microg x kg(-1) x min(-1) (7.5 mL/hr) continuous infusion of colforsin daropate for 60 min. After that, both groups received fentanyl 5 microg/kg. Systolic and diastolic arterial pressure, heart rate, mean airway resistance (Rawm), expiratory airway resistance (Rawe), and dynamic lung compliance (Cdyn) were measured at the baseline, just before the administration of fentanyl (T30), at three consecutive 6-min intervals after fentanyl injection (T36, T42, and T48) and 30 min after fentanyl injection (T60). At baseline, both groups had comparable Rawm, Rawe, and Cdyn values. In the control group, Rawm increased significantly at T36-60 compared with the baseline, Rawe increased significantly at T36-48 compared with the baseline, and Cdyn decreased significantly at T36-60 compared with the baseline. In the colforsin daropate group, there were no changes in Rawm, Rawe or Cdyn at T36-60. CONCLUSIONS: These observations suggest that intravenous colforsin daropate has a bronchodilator effect in humans.