Idiopathic prolonged QT interval and QT dispersion: the effects of propofol during implantation of cardioverter-defibrillator

Local anaesthesia combined with conscious sedation is becoming a popular technique for implantation of cardioverter-defibrillator devices. Propofol was given to provide loss of consciousness during defibrillation shock administration, for induced ventricular fibrillation testing. Propofol was found to decrease QT interval and QT dispersion in two patients with idiopathic prolonged QT interval and QT dispersion. The findings of the procedure are reported.     

A comparison of the effect on QT interval between thiamylal and propofol during anaesthetic induction*

The aim of this study was to determine the effect of thiamylal and propofol on heart rate‐corrected QT (QTc) interval during anaesthetic induction. We studied 50 patients undergoing lumbar spine surgery. Patients were administered 3 μg.kg^?1 fentanyl and were randomly allocated to receive 5 mg.kg^?1 thiamylal or 1.5 mg.kg^?1 propofol as an induction agent. Tracheal intubation was performed after vecuronium administration. Heart rate, mean arterial pressure, bispectral index score, and 12‐lead electrocardiogram were recorded at the following time points: just before (T1) and 2 min after (T2) fentanyl administration; 2 min after anaesthetic administration (T3); 2.5 min after vecuronium injection (T4); and 2 min after intubation (T5). Thiamylal prolonged (p < 0.0001), but propofol shortened (p < 0.0001), the QTc interval.     

QT intervals and QT dispersion in patients with subarachnoid hemorrhage

Purpose. To clarify the clinical significance of QT dispersion and the longest QT intervals (L-QTc) in patients with subarachnoid hemorrhage (SAH). Methods. ECGs, clinical features, and laboratory data were analyzed in 38 patients with SAH (R) and 30 with unruptured cerebral aneurysms (U). Standard 12-lead ECGs obtained on admission were analyzed manually, and the longest QT interval (L-QTc) and the QT dispersion (difference between longest and shortest QTc) were compared between groups. Results. There were no differences between groups R and U in age, sex, or location of aneurysms. The QT dispersion and L-QTc were greater in R than in U (109 ± 49 vs 64 ± 21 ms and 503 ± 63 vs 435 ± 38 ms, respectively; P < 0.01). The QT dispersion and L-QTc were longer in patients with premature ventricular contractions (PVCs) than in patients without PVCs (185 ± 30 vs 85 ± 41 ms and 586 ± 47 vs 467 ± 59 ms, respectively; P < 0.01). There were positive correlations between QT dispersion or L-QTc and preoperative Hunt and Hess grade (rs = 0.560 and rs = 0.615, respectively; P < 0.01). QT dispersion and L-QTc tended to correlate negatively with serum K⁺ (r = −0.365 and r = −0.376, respectively). Conclusion. QT dispersion in patients with SAH is prolonged, especially in high-grade cases. Received: July 19, 2000 / Accepted: November 9, 2000     

Ventilatory effects of eltanolone during induction of anaesthesia: comparison with propofol and thiopentone

We recorded the ventilatory effects of eltanolone 0.75 mg kg-1, propofol 2.5 mg kg-1 and thiopentone 4 mg kg-1 at induction of anaesthesia in 76 unpremedicated patients, aged 18-65 yr. Measurements were made using a pneumotachograph incorporated between a close-fitting face mask and a T-piece delivering 35% oxygen. Eltanolone caused significantly less apnoea than propofol (incidence 57% vs 100%) and less reduction in ventilation than propofol (median maximum decrease 4.8 vs 7.8 litre min-1), but the differences between eltanolone and thiopentone were smaller and generally not significant. Ventilatory frequency was maintained well in the eltanolone group.      

A model of the kinetics and dynamics of induction of anaesthesia in sheep: variable estimation for thiopental and comparison with propofol

We describe a six-compartment kinetic and dynamic physiological model of induction of anaesthesia with thiopental. The model included an accurate account of initial drug distribution by representing the inter- relationships between initial vascular mixing, lung kinetics and cardiac output, and the use of the brain as the target organ for anaesthesia (two-compartment sub-model with slight membrane limitation). It also accounted for thiopental-induced reductions in cerebral blood flow and cardiac output. Parameters for the model were estimated using hybrid modelling from an extensive in vivo data set collected in sheep. Simulations were used to compare the properties of the thiopental model with an analogous previously published model of propofol. Differences in the blood:brain equilibrium half-lives of thiopental (1.22 min) and propofol (4.32 min) contributed to significant differences in the predicted optimal rate of bolus injection of each agent for inducing anaesthesia in sheep.      

QT interval dispersion in dialysis patients

The leading cause of mortality in dialysis patients is cardiovascular complications, including ventricular arrhythmias and sudden cardiac death. A reliable non-invasive predictive test of sudden death is therefore important. The interlead variation in duration of the QT interval on the surface electrocardiogram corrected with heart rate (QTc dispersion) might serve as a surrogate for ventricular arrhythmia. Prolonged QTc dispersion is commonly encountered in dialysis patients and possesses an increased risk of all mortality, including cardiovascular mortality. QT dispersion might be affected by shifts of the intracellular electrolytes during dialysis and increasing deposition of iron in cardiac muscles in these patients who have underlying heart diseases. Although no well-designed study has been done, the factors contributing to prolongation of QTc dispersion should be avoided. We summarize the results of the currently available clinical studies that examined QTc dispersion in dialysis patients.     

Anesthesia induction in children: propofol in comparison with thiopental following premedication with midazolam

Propofol provides smooth and rapid induction of anesthesia in adults and guarantees rapid recovery. The use of propofol in adults is frequently associated with pain on injection, but this can be reduced by: (1) injection into the relatively large veins in the forearm or the antecubital fossa: (2) addition of lignocaine to the propofol; or (3) injection of an opioid (alfentanil) before propofol. Compared with experience in adults, there is very little experience with propofol in pediatric anesthesia. The aim of this random prospective study was to compare the induction characteristics of propofol and thiopentone in pediatric anesthesia. Vigilance and behavior in the postoperative period were also compared. METHOD. A total of 75 healthy children aged 3-12 years who were undergoing elective operations were studied. All the children received premedication with 0.5 mg/kg midazolam with 0.02 mg/kg atropine by the rectal route. The children were divided randomly into 3 groups and received: group A, thiopentone 3-6 mg/kg; group B, propofol 1-3 mg/kg mixed with lignocaine (10/200 mg); group C, propofol 1-3 mg/kg, followed 1 min later by alfentanil 0.01 mg/kg. The induction agent was injected over 30 s, if possible into the vein in the forearm or the antecubital fossa. The immediate reaction on vein puncture and any discomfort during the injection were noted. After intubation the anesthesia was maintained with 1 vol% halothane, nitrous oxide and oxygen (2:1). Arterial pressure was measured on arrival in the induction room, immediately after the induction of anesthesia, immediately after intubation and thereafter at 5-min intervals throughout the anesthesia. Heart rate (ECG) and arterial oxygen saturation (saO2) were measured continuously. The existence of any anterograde amnesia was tested (age over 4 years) by means of one of 6 pictures shown to each before operation. The ability to recall the picture shown was recorded 2-5 h postoperatively. The completeness of recovery was assessed at 10-min intervals up to 1 h, and thereafter at 1-h intervals. In the postoperative period a recovery test (postbox test) was performed. The incidence of side effects during the induction of anesthesia and also during recovery and the postoperative period (for 5 h) was recorded. RESULTS. There was no significant difference between the children in the 3 different groups with regard to age, body weight, type of operation, or duration of anesthesia. Among the total of 75 children, 66.7% accepted the vein puncture very well, and 24% well. In some children in each group we observed obstruction of the respiratory tract (group A, 36%; group B, 48%; group C, 64%). Apnea for 20 s was observed only in groups B and C (2 and 3 children respectively). During spontaneous respiration with room air there was a significant decrease of the arterial oxygen saturation about 1 min after induction in all groups. In children ventilated with oxygen by mask, the SaO2 remained nearly constant...     

Effects of landiolol on QT interval and QT dispersion during induction of anesthesia using computerized measurement

Study ObjectiveTo examine the effects of landiolol on the QT interval, rate-corrected QT (QTc) interval, QT dispersion (QTD), and rate-corrected QTD (QTcD) during tracheal intubation using computerized measurement.DesignRandomized, double-blinded study.SettingDokkyo Medical University Hospital operating room.Patients30 ASA physical status I patients scheduled for elective surgery.InventionsPatients were randomized to receive either normal saline (saline group) or landiolol (landiolol group; one-min loading infusion of 0.125 mg/kg followed by 0.04 mg/kg/min infusion). Immediately after the start of administration of saline or landiolol, anesthesia was induced with intravenous (IV) fentanyl two μg/kg, propofol 1.5 mg/kg, and vecuronium 0.1 mg/kg. Six minutes after administration of saline or landiolol, tracheal intubation was performed within 20 seconds.MeasurementsMean arterial pressure (MAP), RR interval, QT interval, QTc interval, QTD, and QTcD were consecutively recorded during the induction.Main ResultsThere was no significant difference in MAP between groups during the study. RR interval in the landiolol group was significantly longer than in the saline group from two minutes after the start of the landiolol infusion to the end of the study. The QT interval in the landiolol group was significantly shorter than in the saline group from start of the infusion to 4 minutes after tracheal intubation. The QTc interval, QTD, and QTcD in the landiolol group were significantly shorter than those in the saline group from immediately after tracheal intubation to the end of study.ConclusionA bolus of landiolol 0.125 mg/kg followed by an infusion of landiolol 0.04 mg/kg/min may reduce the risk of cardiac arrhythmias during induction of anesthesia.     

The interaction of antiemetic dose of droperidol with propofol on QT interval during anesthetic induction

Purpose

We investigated the effect of low-dose droperidol on heart rate-corrected QT (QTc) interval and interaction with propofol.

Methods

Seventy-two patients undergoing upper limb surgery were included in this study. Patients were randomly allocated to one of three groups: group S (n = 24), which received 1 ml saline; group D1 (n = 24), which received 1.25 mg droperidol; or group D2 (n = 24), which received 2.5 mg droperidol. One minute later, fentanyl (3 μg/kg) was administered. Two minutes after fentanyl administration, anesthesia was induced using propofol (1.5 mg/kg) and vecronium. Tracheal intubation was performed 3 min after the administration of propofol. Heart rate, mean arterial pressure, bispectral index, and QTc interval were recorded at the following time points: immediately before the droperidol injection (baseline); 3 min after the saline or droperidol injection; 3 min after the propofol injection; and 2 min after tracheal intubation.

Results

Compared to baseline, the QTc interval in group S and group D1 was significantly shorter after propofol injection, but recovered after tracheal intubation. In group D2, the QTc interval was significantly prolonged after droperidol injection, but recovered after propofol injection, and was significantly prolonged after tracheal intubation.

Conclusions

We found that saline or 1.25 mg droperidol did not prolong QTc interval, whereas 2.5 mg droperidol prolonged the QTc interval significantly, and that propofol injection counteracted the prolongation of the QTc interval induced by 2.5 mg droperidol.     

Haemodynamic effects of induction of general anaesthesia with propofol during epidural anaesthesia

PURPOSE: To clarify whether propofol administration during thoracic or lumbar epidural anaesthesia intensifies the haemodynamic depression associated with epidural anaesthesia. METHODS: Patients (n = 45) undergoing procedures of similar magnitude were randomly divided into three study groups: a control group (n = 15) receiving general anaesthesia alone and two study groups undergoing thoracic (n = 15) and lumbar epidural anaesthesia (n = 15) before induction of general anaesthesia. All patients received 2 mg.kg-1 propofol at a rate of 200 mg.min-1, followed by a continuous infusion of 4 mg.kg-1.hr-1. Mean arterial blood pressure (MAP) and heart rate (HR) were measured at baseline, three minutes after induction, and one minute after tracheal intubation in all three groups and at 20 min after epidural anaesthesia was established in the thoracic and lumbar groups. RESULTS: Following epidural anaesthesia, MAP decreased from 94 +/- 14 (SD) at baseline to 75 +/- 11 mmHg (P < 0.0001) in the thoracic group and from 92 +/- 12 to 83 +/- 15 mmHg in the lumbar group. After propofol administration, MAP decreased further in the thoracic group to 63 +/- 9 mmHg (P = 0.0077) and to 67 +/- 10 mmHg (P = 0.0076) in the lumbar group. The MAP following propofol induction in the thoracic group (P < 0.0001) and in the lumbar group (P = 0.0001) was lower than MAP in the control group (81 +/- 9 mmHg). HR decreased only in response to thoracic epidural anaesthesia (P = 0.0066). CONCLUSION: The hypotensive effects of propofol are additive to those of epidural anaesthesia, resulting in a profound decrease in mean arterial pressure.     

QT interval,heart rate and arterial pressures using propofol,thiopentone or methohexitone for induction of anaesthesia in children

The effects on corrected QT interval (QTc), heart rate and arterial pressure were studied after induction with propofol 1.5, 2 or 2.5 mg'kg^-1, thiopentone 5 mg-kg^-1 or methohexitone 2 mg-kg^-1 in 123 ASA class I or II children undergoing outpatient otolaryngological surgery. Premedication consisted of oral midazolam and atropine. The children were randomly allocated to one of the three propofol groups or to the thiopentone or methohexitone group. After injection of the intravenous anaesthetic, the QTc interval was significantly prolonged after propofol 2.5 mg. kg^-1. Thirty seconds after suxamethonium 1.5 mg kg^-1, a significant prolongation of the QTc interval occurred in the thiopentone and propofol 1.5 and 2 mg-kg^-1 groups. After intubation, no further prolongation of the QTc interval occurred in any of the groups. Heart rate increased significantly after the barbiturates but not after propofol. Systolic arterial pressure decreased significantly after propofol 1.5 and 2.5 mg kg^-1. In all groups a cardiovascular intubation response occurred. Bradycardia and junctional rhythm occurred in 4% of the children in both barbiturate groups and in 19–29% in the propofol groups. It is concluded that propofol causes prolongation of the QT interval and results in a higher incidence of bradycardia and junctional rhythm than the barbiturates.     

QT interval and QT dispersion increase in the elderly during laparoscopic cholecystectomy: A preliminary study

PURPOSE: To compare the influence of a longer duration of intraperitoneal CO2 insufflation with head-up tilt on electrocardiogram indices during laparoscopic cholecystectomy between elderly and younger patients. METHODS: Twelve elderly and 12 younger patients were studied. In all patients, intraperitoneal CO2 insufflation was performed for more than 150 min in the head-up position. RR interval, QT interval, the rate-corrected QT (QTc) interval, QT dispersion (QTD) and the rate-corrected QTD (QTcD) were measured. RESULTS: The QT interval and the QTc interval increased significantly from 120 to 150 min after CO2 insufflation in the elderly. The QTD and QTcD increased significantly during CO2 insufflation in both groups. Those were significantly greater in the elderly than in younger patients from 120 to 150 min after CO2 insufflation. CONCLUSION: Longer duration of CO2 insufflation with head-up tilt is associated with a prolongation of the QT interval and the QTD in elderly patients. The clinical significance of these findings remains to be determined.     

Differences between bispectral index and spectral entropy during xenon anaesthesia: a comparison with propofol anaesthesia

We enrolled 114 patients, aged 65–83 years, undergoing elective surgery (duration > 2h) into a randomised, controlled study to evaluate the performance of bispectral index and spectral entropy for monitoring depth of xenon versus propofol anaesthesia. In the propofol group, bispectral index and state entropy values were comparable. In the xenon group, bispectral index values resembled those in the propofol group, but spectral entropy levels were significantly lower. Mean arterial blood pressure was higher and heart rate was lower in the xenon group than in the propofol group. Bispectral index and spectral entropy considerably diverged during xenon but not during propofol anaesthesia. We therefore conclude that these measures are not interchangeable for the assessment of depth of hypnosis and that bispectral index is likely to reflect actual depth of anaesthesia more precisely compared with spectral entropy.     

QT interval of the ECG, heart rate and arterial pressure using propofol, methohexital or midazolam for induction of anaesthesia

The effects of propofol 2 mg/kg, methohexital 2 mg/kg or midazolam 0.3 mg/kg were studied on the QT interval of the ECG corrected by the heart rate (QTc), heart rate and arterial pressure during induction of anaesthesia in 87 ASA class I-(II)-patients. The patients were randomly allocated to one of the three anaesthetic groups. The incidence of the patients with a prolonged QTc interval (= more than 440 ms) ranged from 29 to 41% between the groups. In each group these patients were treated separately. After all anaesthetics, the QTc interval was significantly prolonged in the patients with a normal control QTc interval, whereas in the patients with a prolonged control QTc interval, it tended to be shortened both after propofol and methohexital and it was significantly shortened after midazolam. After injection of suxamethonium, no significant QTc interval changes occurred in the patients with a normal control QTc interval in either the propofol or the methohexital groups, whereas in the patients with a prolonged control QTc interval treated with propofol the QTc interval decreased significantly 60 s after suxamethonium when compared with the corresponding preceding values. The mean values in the propofol group in the patients with a normal control QTc interval were always below the upper limit of the normal range.(ABSTRACT TRUNCATED AT 250 WORDS)     

Total intravenous anaesthesia with propofol and remifentanil in paediatric patients: a comparison with a desflurane-nitrous oxide inhalation anaesthesia

Background : Remifentanil is a new rapid-acting and ultra-short-acting μ-opioid receptor agonist with few reports from use in children. Therefore, we compared a propofol-remifentanil-anaesthesia (TIVA) with a desflurane-N₂O-anaesthesia (DN) with particular regard to the recovery characteristics in children.
Methods : 50 children (4–11 yr) scheduled for ENT surgery were randomly assigned to receive TIVA (n=25) or DN (n=25). After standardised i.v. induction of anaesthesia in both groups with remifentanil, propofol and cisatracurium, TIVA was maintained with infusions of propofol and remifentanil. Ventilation was with oxygen in air. DN was maintained with desflurane in 50% N₂O. The administration of volatile and intravenous anaesthetics was adjusted to maintain a surgical plane of anaesthesia. At the end of surgery all anaesthetics were terminated without tapering and early emergence and recovery were assessed. In addition, side effects were noted.
Results : Both anaesthesia methods resulted in stable haemodynamics but significantly higher heart rate with desflurane. Recovery did not differ between the groups except for delayed spontaneous respiration after TIVA. Spontaneous ventilation occurred after 11±3.7 min versus 7.2±2.8 min (mean±SD, TIVA versus DN), extubation after 11±3.7 min versus 9.4±2.9 min, eye opening after 11 ±3.9 min versus 14±7.6 min and Aldrete score ≥9 after 17±6.8 min versus 17±7.5 min. Postoperatively, there was a significant higher incidence of agitation in the DN-group (80% vs. 44%) but a low incidence (<10%) of nausea and vomiting in both groups.
Conclusion : In children, TIVA with remifentanil and propofol is a well-tolerated anaesthesia method, with a lower peroperative heart rate and less postoperative agitation compared with a des-flurane-N₂O based anaesthesia.     

Ventilatory effects of propofol during induction of anaesthesia

The ventilatory effects of induction of anaesthesia with either propofol 2.5 mg/kg or thiopentone 4.0 mg/kg have been observed in patients premedicated with either atropine alone or papaveretum and hyoscine. Induction of anaesthesia with propofol was accompanied by a greater degree of ventilatory depression which was of longer duration than following thiopentone. The effect was accentuated by the opioid premedication.