Esmolol bolus and infusion attenuates increases in blood pressure and heart rate during electro-convulsive therapy

To determine whether a standardized dose of esmolol can effectively attenuate the cardiovascular response to electroconvulsive therapy (ECT), 17 ASA physical status I-II patients were studied in a randomized within-patient, crossover design. Each patient received "no esmolol" during one ECT and three to five days later crossed over to the alternative treatment receiving an esmolol 80 mg bolus followed by 24 mg.min-1 infusion two minutes prior to induction of anaesthesia and continued for five minutes after induction. Esmolol blunted the maximum increases in heart rate (HR) by 26 per cent, mean arterial pressure (MAP) by 14 per cent, and rate pressure product by 37 per cent with significant differences (P less than 0.05) noted at one, two, three and four minutes after ECT (minutes five, six, seven, and eight of the esmolol infusion). There was no significant difference in seizure duration between the two groups and no adverse reactions occurred.     

Remifentanil prevents an increase in intraocular pressure after succinylcholine and tracheal intubation

We have studied changes in intraocular pressure (IOP) in 30 patients after succinylcholine (suxamethonium) and tracheal intubation following administration of propofol 2 mg kg-1 and either remifentanil 1 microgram kg-1 (group R) or saline (group S). IOP was measured before induction, before administration of succinylcholine and the study drug, before intubation and for every 1 min after intubation for 5 min. There was a significant decrease in IOP in group R compared with group S from the time of administration of the study drugs to the end of the study (P < 0.006).      

Effect of remifentanil compared with fentanyl on intraocular pressure after succinylcholine and tracheal intubation

Rapid sequence induction using succinylcholine is associatedwith an increase in intraocular pressure (IOP). This may leadto loss of ocular contents in open globe injuries. No methodhas previously been shown to prevent this increase in IOP. Weinvestigated whether remifentanil, an ultra-short-acting opioid,could attenuate this increase in IOP during rapid sequence inductionof anaesthesia. Forty-five patients were randomized blindlyto receive remifentanil 1 µg kg^–1, fentanyl 2 µgkg^–1 or placebo 1 min before thiopental, succinylcholineand tracheal intubation. IOP and haemodynamic variables weremeasured before, 1 min after the test solution, 30 s after thiopental,30 s after succinylcholine, immediately after intubation andthen every 3 min for 9 min. Remifentanil obtunded the increasein IOP after succinylcholine and intubation, so it could besuitable for use in open globe injuries. Br J Anaesth 2000; 85: 785–7 Footnotes ^* Corresponding author     

Comparative effects of thiopentone and propofol on respiratory resistance after tracheal intubation

To compare the effects of propofol and thiopentone on tracheal intubation-induced bronchoconstriction, 37 patients were allocated randomly to anaesthesia with either thiopentone 4 mg kg-1 followed by a 15-mg kg-1 h-1 continuous infusion or propofol 3 mg kg-1 followed by a 9-mg kg-1 h-1 continuous infusion. Intubation was facilitated by vecuronium 0.1-0.2 mg kg-1. Respiratory system resistance (Rrs) was measured by a CP-100 pulmonary function monitor, 5 min after intubation. The 5-min post-intubation Rrs values were significantly lower in the propofol group (8.5 (SD 1.5) cm H2O litre-1 S-1) than in the thiopentone group (10.9 (3.2) cm H2O litre-1 S-1). Thirty minutes after commencing isoflurane-nitrous oxide anaesthesia, Rrs declined by 17.5 (SEM 3.6)% from baseline in the thiopentone group, but by only 1.6 (2.6)% in the propofol group. We conclude that the dose of propofol administered provided more protection against tracheal intubation- induced bronchoconstriction than an induction dose of thiopentone.      

The neuromuscular effects and tracheal intubation conditions after small doses of succinylcholine

Succinylcholine 1.0 mg/kg usually produces excellent tracheal intubation conditions in 60 s. Recovery of respiratory muscle function after this dose, however, is not fast enough to forestall oxyhemoglobin desaturation when ventilation cannot be assisted. In this study, we investigated whether smaller doses of succinylcholine can produce satisfactory intubation conditions fast enough to allow rapid sequence induction with a shorter recovery time. Anesthesia was induced with fentanyl/propofol and maintained by propofol infusion and N(2)O in O(2). After the induction, 115 patients were randomly allocated to five groups according to the dose of succinylcholine (0.3 mg/kg, 0.4 mg/kg, 0.5 mg/kg, 0.6 mg/kg, or 1.0 mg/kg). Evoked adductor pollicis responses to continuous 1-Hz supramaximal ulnar nerve stimulation were recorded using acceleromyography. Tracheal intubation conditions were graded 60 s after succinylcholine administration. Onset time, maximal twitch depression, time to initial twitch detection after paralysis, and to 10%, 25%, 50%, and 90% twitch height recovery were recorded. Time to initial diaphragmatic movement as well as time to resumption of regular spontaneous respiratory movements were calculated. Onset times ranged between 82 s and 52 s, decreasing with increasing doses of succinylcholine but not differing between 0.6 and 1 mg/kg. Maximum twitch depression was similar after 0.5, 0.6, and 1 mg/kg (98.2%-100%). Recoveries of twitch height and apnea time were dose-dependent. Intubation conditions were often unacceptable after 0.3- and 0.4-mg/kg doses. Acceptable intubation conditions were achieved in all patients receiving a 0.5, 0.6, and 1 mg/kg dose of succinylcholine. Intubation conditions in patients receiving 0.6 and 1 mg/kg were identical, whereas times to T(1) = 50% and 90% and time to regular spontaneous reservoir bag movements were significantly shorter in the 0.6-mg/kg dose group (5.78, 7.25, and 4.0 min, respectively) versus patients receiving 1 mg/kg (8.55, 10.54, and 6.16 min, respectively). The use of 0.5 to 0.6 mg/kg of succinylcholine can produce acceptable intubation conditions 60 s after administration. The conditions achieved after 0.6 mg/kg are similar to those after 1.0 mg/kg. These smaller doses are associated with faster twitch recovery and shorter apnea time. IMPLICATIONS: In normal healthy patients, succinylcholine 0.6 mg/kg produces clinical intubation conditions identical to the traditional 1.0-mg/kg dose but is associated with a shorter recovery time.     

Heart rate and arterial pressure changes during fibreoptic tracheal intubation under general anaesthesia

The cardiovascular responses to fibreoptic orotracheal intubation under general anaesthesia were compared with those in a control group in whom tracheal intubation was effected with a Macintosh laryngoscope. The patients received a standard anaesthetic and were allocated randomly to either group immediately before intubation. Fibreoptic intubation took significantly longer to perform. There were significant increases in heart rate and arterial pressure in both groups compared with pre-induction values. The tachycardia in the fibreoptic group was significantly greater than that in the control group during the second minute after intubation, and the increase in systolic pressure was sustained for a longer period in the fibreoptic group. The maximum increases in systolic and diastolic pressures above pre-intubation values were significantly greater in the fibreoptic group. The cardiovascular responses associated with fibreoptic intubation under general anaesthesia appear to be more severe than those which follow intubation effected with a Macintosh laryngoscope.     

艾司洛尔与表面麻醉抑制插管反应时心率变异性的变化

目的比较观察全麻病人气管插管前静脉给予艾司洛尔或用表面麻醉抑制插管反应 时心率变异性(HRV)的变化。方法120例病人随机分为三组,每组40例,Ⅰ组为艾司洛尔组,Ⅱ组为单纯喉气管表面麻醉(LTA)组,Ⅲ组为口咽表面喷雾加LTA组。静注芬太尼2μg·kg-1,异丙酚2mg·kg-1,维库溴铵0．1mg·kg-1诱导插管。Ⅰ组病人插管前2min,静注艾司洛尔2mg·kg-1;Ⅱ组病人用喉镜暴露声门,用1％地卡因2．5ml行会厌、声门及气管内的表面麻醉2min后再行插管;Ⅲ组病人于麻醉前清醒时,用1％地卡因约0．5ml作舌背、软腭、咽及喉部喷雾,其余操作均与Ⅱ组相同。结果除Ⅰ组病人在插管即刻和插管后1min心率明显低于Ⅱ、Ⅲ组外(P<0．05),其它两组病人在插管前后血压、心率均无明显变化。HRV和LF在插管前后只有Ⅲ组保持不变,而Ⅰ、Ⅱ组病人在插管即刻、插管后1min均显著高于Ⅲ组(P<0．01)。Ⅲ组病人的LF／HF在插管即刻及插管后1min出现明显降低(P<0．05),与Ⅰ、Ⅱ组相比有显著性差异。结论插管前静脉注射艾司洛尔不能抑制应激反应的产生;表面麻醉能从根本上抑制应激反应的发生,但在插入喉镜前仍需完善的口咽喉部局麻作保证。     

Change in tracheal blood flow during endotracheal intubation

Changes in blood flow in the tracheal mucosa of the dog caused by the pressure exerted by high volume, low-pressure cuffs were measured with the hydrogen clearance method. Before inflating the cuffs, the blood flow of the tracheal mucosa was measured as a control for 12 h in order to confirm that the procedures of the hydrogen clearance method itself had little or no influence on the blood flow in the tracheal mucosa. After inflating the cuffs to create a tracheal wall pressure (TWP) of 1.3 kPa (10 mmHg), 2.6 kPa (20 mmHg), 3.9 kPa (30 mmHg) or 6.0 kPa (45 mmHg), local blood flows of tracheal mucosa (TBF) corresponding to each TWP were measured every hour for 12 h. No significant changes in blood flow were observed in the tracheal mucosa with the hydrogen clearance method before inflating the cuffs. In the groups with TWP of 1.3 and 2.6 kPa, the TBF rose 1 h after inflation of the cuffs, and then returned to the baseline values. In the group with TWP of 6.0 kPa, the TBF decreased markedly already 1 h after inflation of the cuffs, and continued to decrease severely thereafter. In the group with TWP of 3.9 kPa, the TBF followed an intermediate course between the groups with TWP of 2.6 kPa and 6.0 kPa. From the results of the present study, it was found that TBF was significantly impaired by a TWP of more than 3.9 kPa. Therefore, in prolonged intubation, TWP should be kept at or below 2.6 kPa.     

Suppression of blood pressure increases during intubation: lidocaine or fentanyl?

The hypertensive response to anesthetic induction with endotracheal intubation may be harmful in patients with cardiovascular disease, increased intracranial pressure, or anomalies of the cerebral vessels. Recommendations for attenuating the reflex hypertension and tachycardia elicited by upper airway irritation are therefore manifold. Besides minimizing the cardiovascular response, anesthesia induction for patients at risk must also satisfy the following requirements: it must be applicable regardless of patient collaboration, prevent impairment of cerebral blood flow, and avoid arousal of the patient; it should neither be time-consuming nor affect the duration or modality of the ensuing anesthesia. Among the recommended procedures, intravenous lidocaine or fentanyl appear to best fulfill the above mentioned criteria. However, our own equivocal observations and controversial results in the literature concerning the efficacy of intravenous lidocaine prompted us to reinvestigate the issue in two well-defined patient groups. In 46 patients with intracranial vessel malformations and 78 patients with brain tumors, blood pressure responses to endotracheal intubation were studied under anesthesia induction with 1.5 mg/kg lidocaine or 6 micrograms/kg fentanyl i.v. 30 s before thiopental injection or 2-3 min before intubation. The two equally simple induction procedures were compared to anesthesia induction with thiopental alone. In both patient groups no significant effect of lidocaine on the pressure response could be observed. Fentanyl lowered the pressure response slightly though significantly in brain-tumor patients only (p less than 0.05), but showed a significant pressure-lowering action persisting over the whole observation period in all patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Double-blind comparison of sevofluran vs propofol and succinylcholine for tracheal intubation in children

We have studied intubating conditions in 64 healthy children, aged 3-10 yr, undergoing adenotonsillectomy, in a double-blind, randomized study. Intubation was performed 150 s after induction using either 8% sevoflurane in nitrous oxide and oxygen or propofol 3-4 mg kg-1 with succinylcholine 2 mg kg-1. An anaesthetist blinded to the technique performed intubation and scored intubating conditions using Krieg and Copenhagen Consensus Conference (CCC) scores. The trachea was intubated successfully at the first attempt in all patients under clinically acceptable conditions, although scores were significantly better with propofol and succinylcholine. The sevoflurane technique cost 3.62 +/- 0.55 Pounds to completion of tracheal intubation, significantly more (P < 0.001) than the cost of propofol-succinylcholine and isoflurane (2.04 +/- 0.54 Pounds) when based on actual amount of drug used. This cost increased to 4.38 +/- 0.05 Pounds when based on whole ampoules, which is significantly more than the cost of sevoflurane (P < 0.001).      

Intubating conditions and haemodynamic changes following thiopentone or propofol for early tracheal intubation

Intubating conditions and haemodynamic changes were studied 30 sec after a fixed induction dose of thiopentone or propofol in patients scheduled for elective surgery. The hypnotic agent was preceded by the administration of papaveretum 10 mg three minutes before induction and alcuronium 0.2 mg·kg^?1 at induction. Ease of intubation was graded and the study conducted in a randomised double-blind fashion. In the thiopentone group (n=30) intubation was very easy in 73% compared with 79% in the propofol group (n=29). In two patients in the propofol group the tracheas were moderately difficult to intubate but there were no failed intubations in either group. No patients recalled the intubation period on subsequent postoperative questioning. The immediate post-induction average systolic pressure in the thiopentone group decreased by 0.7% (range 15.9% increase to 25.3% decrease) whilst the post-intubation systolic pressure increased by 6.3% (range ?31.5% increase to 24.2% decrease). In the propofol group there was a decrease in systolic pressure after induction (average 14.4%; range 15.5% increase to 41.4% decrease, P < 0.05) but the subsequent pressor response to intubation was markedly attenuated compared with baseline (average systolic pressure decreased 15.5% (range 22.4% increase to 42.7% decrease)). Following intubation and maintenance, ventilation with nitrous oxide 70% and halothane 1% the systolic pressure decreased markedly in both groups with a greater reduction in the propofol group (P < 0.05). Compared with baseline there were increases (P < 0.0001) in heart rate in both groups from induction of anaesthesia to the end of study. The results show that early tracheal intubation can be undertaken following thiopentone and is accompanied by haemodynamic stability. Comparable intubating conditions are associated with propofol but the dose used resulted in a considerable decrease in systolic blood pressure after induction.     

Heart rate and blood pressure effects of esmolol after ketamine induction and intubation

Both ketamine and tracheal intubation are associated with increased heart rate (HR) and systolic blood pressure (SBP). Beta blockers prevent or attenuate this increase. Esmolol (E) is a new, intravenous, rapidly metabolized beta blocker. An open-label study was performed in 41 ASA Class II and III patients divided into groups 1-4: control, 100, 200, and 300 micrograms X kg-1 X min-1 (n = 10, 10, 11, and 10, respectively). E was infused over 10 min, the first one-fourth of which was a loading dose of 500 micrograms X kg-1 X min-1; at 4 min, ketamine was followed by succinylcholine, intubation, and enflurane-N2O-O2. HR, SBP, blood E, and plasma catecholamine levels were obtained during the 40 min of study. The control group had a baseline HR of 83 +/- 5 beats/min while esmolol groups 2-4 had an HR of 73 +/- 3, 72 +/- 3, and 68 +/- 4 beats/min, respectively (P less than 0.05). After ketamine, the control group HR increased to 93 +/- 6 beats/min and groups 2-4 remained at the baseline level, 73 +/- 3, 73 +/- 3 and 67 +/- 4 beats/min, respectively (P less than 0.05). Postintubation, the control increased further to 113 +/- 5 beats/min while groups 2-4 were significantly less, 91 +/- 5, 84 +/- 3, and 78 +/- 4 beats/min, respectively. The mean SBP in most E groups was less than the control within groups, but only in group 4 between groups was the SBP less at postintubation (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)