Atropine-induced heart rate changes: a comparison between midazolam-fentanyl-propofol-N2O and midazolam-fentanyl-thiopentone-enflurane-N2O anaesthesia

Atropine-induced heart rate (HR) changes were studied in 19 patients (ASA physical status I) during anaesthesia maintained predominantly with propofol-N₂O or thiopentone-enflurane-N₂O. Ten patients (Group A) received midazolam (0.07 mg · kg^?1), fentanyl (1 μg · kg^?1), propofol (2 mg · kg^?1) and succinylcholine (1 mg · kg^?1). Following tracheal intubation, anaesthesia was maintained with propofol (6 mg · kg^?1 · hr^?1), N₂O (67 per cent) and O₂ (33 per cent). In nine patients (Group B) thiopentone (4 mg · kg^?1) was substituted for propofol and anaesthesia maintained with N₂O (67 per cent) O₂ (33 per cent), and enflurane (0.5 per cent inspired concentration). The study was non-randomised because Group B patients were only included if HR before administration of atropine < 90 beats · min^?1. IPPV was performed in all patients using a Manley ventilator (minute vol. 85 ml · kg^?1; tidal vol. 7 ml · kg^?1). Ten minutes after tracheal intubation, incremental doses of atropine (equivalent cumulative doses: 1.8, 3.6, 7.2, 14.4, 28.8 μg · kg^?1) were administered at two-minute intervals and HR responses calculated during the last 45 sec of each intervening period. No differences were observed between the groups following 1.8 and 3.6 μg · kg^?1 atropine, but propofol-N₂O anaesthesia was associated with reduced responses (P < 0.01) following 7.2, 14.4 and 28.8 μg · kg^?1 atropine. These results suggest that there is a predominance of parasympathetic influences during propofol-N₂O anaesthesia compared with thiopentone-enflurane-N₂O anaesthesia.     

Midazolam coinduction does not delay discharge after very brief propofol anaesthesia

Previous reports have demonstrated synergism of midazolam and propofol for induction of anaesthesia in humans. We tested the hypothesis that in the presence of alfentanil, the combination of midazolam with propofol for a very brief operative procedure would not affect the recovery phase. During pre-oxygenation, 64 outpatients scheduled for dilatation and curettage received placebo, or low-dose midazolam (0.03 mg · kg^?1), or high-dose midazolam (0.06 mg · kg^?1) iv, in a randomized double-blind manner. They then received alfentanil 10 μg · kg^?1 iv, followed by titrated doses of propofol iv for induction and maintenance of anaesthesia. Ventilation with 70% N₂O in O₂ by mask was controlled to achieve a PETCO₂ 30–40 mmHg. Outcome measures were: propofol dose (induction and maintenance), time until eye-opening to command, and time to discharge-readiness. Propofol induction dose was decreased by increasing doses of midazolam (P = 0.00005). Midazolam delayed time to eye-opening (P = 0.02) but not time to discharge-readiness. This study had an 80% power to detect a 39 min difference in time to discharge-readiness. We conclude that midazolam propofol co-induction in the presence of alfentanil delays eye-opening, but does not delay discharge after anaesthesia.     

Comparison of fentanyl,sufentanil and alfentanil during awake craniotomy for epilepsy

Neurolept anaesthesia is used during awake craniotomy for epilepsy surgery. This study compares analgesia, sedation and the side effects of the newer opioids sufentanil and alfentanil, with those of fentanyl in patients undergoing awake craniotomy. Thirty patients were randomized into three groups, each received droperidol, dimenhydrinate and the chosen opioid as a bolus followed by an infusion. The opioid doses used were fentanyl 0.75 μg · kg^?1 plus 0.01 μg · kg^?1 · min^?1; sufentanil 0.075 μg · kg^?1 plus 0.0015 μg · kg^?1 · min^?1, and alfentanil 7.5 μg · kg^?1 plus 0.5 μg · kg^?1 · min^?1. There were no differences in the requirements for droperidol, dimenhydrinate or in the incidence of complications among the three groups. The total doses of the opioids required were fentanyl 4.9 ±1.3 μg · kg^?1, sufentanil 0.6 ±0.2 μg · kg^?1 and alfentanil 149 ±36 μg · kg^?1. Two patients became uncooperative requiring general anaesthesia. The conditions for surgery, electrocorticography and for stimulation testing were satisfactory in all other patients. We conclude that the newer opioids did not offer any benefit over fentanyl.     

Comparaison du retentissement hémodynamique d'une association midazolam-fentanyl et thiopental-fentanyl à l'induction d'une anesthésie générale

The haemodynamic changes during anaesthetic induction for elective abdominal aortic surgery were studied in two groups of patients. Group M (9 patients) received midazolam 0.3 mg · kg^?1 and fentanyl 5 μg · kg^?1. Group T (10 patients) received thiopentone 6 mg · kg^?1 and fentanyl 5 μg · kg^?1. The radial and pulmonary arteries were catheterized under local anesthesia. An intravenous infusion was administered in order to normalize pulmonary wedge pressure. Systemic and pulmonary arterial pressures, pulmonary wedge pressure, cardiac output and heart rate were measured after the infusion and 5 min after intubation. Mean arterial pressure showed a statistically significant reduction in both groups. Cardiac index remained unchanged in group M, but was significantly diminished in group T. There was no significant reduction in the systemic vascular resistance index for group M, but group T showed a statistically significant increase. This study confirmed the good haemodynamic tolerance of the midazolam induction technique, even with a high dose of 0.3 mg · kg^?1.     

Conscious sedation for interventional neuroradiology: a comparison of midazolam and propofol infusion

Purpose

The aim of this study was to compare two conscious sedation techniques, midazolam (M) and propofol (P), for interventional neuroradiology by assessment of the incidence of complications and satisfaction scores.

Methods

Forty patients were randomized to receive 0.75 μg · kg^?1 fentanyl and a M or P bolus followed by an infusion; (M I5 μg · kg^?1 + 0.5 μg · kg^?1 · min^?1: P 0.5 mg · kg^?1 + 25 μg · kg^?1 min^?1). The incidences of complications and untoward events requinng intervention were documented. These included respiratory depression, excessive pain, inappropriate movements and the inability to examine the patient. The satisfaction of the anaesthetic technique from the perspective of both the neuroradiologist and the patient was scored.

Results

The incidence and types of complications were not different between the two groups. Pain occurred in 12 patients (6M, 6P), inappropriate movements in 17 (7M, 10P) and respiratory changes in 10 patients (2M, 8P).

Conclusions

Both techniques were satisfactory and the incidence of complications was similar for both groups.     

Midazolam reverses histamine-induced bronchoconstriction in dogs

Purpose

Midazolam has been used clinically as a sedative and as an anaesthetic induction agent. However, the bronchodilating effects of midazolam have not been comprehensively evaluated. We sought to determine relaxant effects of midazolam on the airway.

Methods

After our Animal Care Committee approved the study, eight mongrel dogs were anaesthetized with 30 mg · kg^?1 pentobarbitoneiv, and were paralysed with 200 μg · kg^?1 · hr^?1 pancuronium. The trachea was intubated with an endotracheal tube (ID 7 mm) that had a second lumen for insertion of a superfine fibreoptic bronchoscope (OD 2.2 mm) to measure the bronchial cross-sectional area (BCA) continuously. The tip of the bronchoscope was placed at the level of the second or third bronchial bifurcation of the nght bronchus. A videopnnter printed the BCA which was then measured with a NIH Image program. Bronchoconstnction was produced with histamine (H) 10 μg · kg^?1 followed by 500 μg · kg^?1 · hr^?1. Thirty minutes later, 0 [saline], 0.01, 0.1 and 1.0 mg · kg^?1 midazolam and 25 μg · kg^?1 flumazenil were given. The BCA was assessed before (basal area) and 30 min after the start of H infusion, and was also measured five minutes after each midazolam and flumazeniliv. At the same time, arterial blood was sampled for plasma catecholamine measurement.

Results

Histamine infusion decreased BCA to 49.7 ± 17.3% of basal BCA More than 0.1 mg · kg^?1 midazolam increased BCA up to 71.7 ± 15.3% of the basal (1.0 mg · kg^?1) (P < 0.01). Plasma adrenaline concentration was decreased from 6.9 ± 3.8 to 3.7 ± 1.9 ng · ml^?1 by 1.0 mg · kg^?1 midazolam (P < 0.05). Flumazenil did not antagonize the relaxant effect of midazolam but reversed the inhibitory effect of midazolam on histamine-induced adrenaline release.

Conclusion

Midazolam has a spasmolytic effect on constricted airways but this bronchodilatation was not reversed by flumazenil.     

Midazolam for caudal analgesia in children: comparison with caudal bupivacaine

In a randomized, double-blind study we have examined the analgesic efficacy of caudal administration of midazolam, bupivacaine, or a mixture of both drugs in 45 children, undergoing inguinal herniotomy. They were allocated randomly into three groups (n = 15 in each) to receive a caudal injection of either 0.25% bupivacaine 1 ml · kg^?1 with or without midazolam 50 μg · kg^?1 or midazolam 50 μg · kg^?1 with normal saline 1 ml · kg^?1. There were no differences in quality of pain relief, postoperative behaviour or analgesic requirements between the midazolam group and the other two groups. Times to first analgesic administration (paracetamol suppositories) were longer (P < 0.001) in the bupivacaine-midazolam group than in the other two groups. Further, the bupivacaine-midazolam group received fewer (P < 0.05) doses of paracetamol than the bupivacaine group. Side effects such as motor weakness, respiratory depression or prolonged sedation were not observed in patients who received caudal epidural midazolam only. We conclude that caudal midazolam in a dose of 50 μg · kg^?1 provides equivalent analgesia to bupivacaine 0.25%, when administered postoperatively in a volume of 1 ml · kg^?1 for children following unilateral inguinal hemiotomy.

     

Post-herniorrhaphy pain in outpatients after preincision ilioinguinal-hypogastric nerve block during monitored anaesthesia care

The objective of this study was to evaluate the effect of an ilioinguinal-hypogastric nerve block (IHNB) with bupivacaine 0.25% on the postoperative analgesic requirement and recovery profile in outpatients undergoing inguinal herniorrhaphy with local anaesthetic infiltration. Thirty consenting healthy men undergoing elective unilateral inguinal herniorrhaphy procedures were randomly assigned to receive an IHNB with either saline or bupivacaine according to a double-blind, IRB-approved protocol. All patients received midazolam, 2 mg iv, and fentanyl 25 μg iv, prior to injection of 30 ml of either bupivacaine 0.25% or saline through the oblique muscle approximately 1.5 cm medial to the anterior superior iliac spine. Subsequently, the surgeon infiltrated the incision site with a lidocaine 1% solution. Sedation was maintained during the operation with a variable-rate propofol infusion, 25–140 μg · kg^?1 · min^?1. No significant differences were noted in the intraoperative doses of lidocaine, propofol and fentanyl in the two treatment groups. However, the pain visual analogue score at 30 min after entering the PACU was lower in the bupivacaine (versus saline) group (P < 0.05). Although the times to ambulation (86 ± 18 vs 99 ± 27 min) and being judged “fit for discharge” (112 ± 49 vs 126 ± 30 min) were similar in the two groups, the bupivacaine-treated (vs saline) patients required less oral analgesic medication after discharge (46% vs 85%). We concluded that the use of an ilioinguinal-hypogastric nerve block with bupivacaine 0.25% as an adjuvant during inguinal herniorrhaphy under monitored anaesthesia care decreased pain in the PACU and oral analgesic requirements after discharge from the day-surgery unit.     

Optimizing sedation following major vascular surgery: a double-blind study of midazolam administered by continuous infusion

A randomized, double-blind study was undertaken to determine the dose requirements, recovery characteristics, and pharmacokinetic variables of midazolam given by continuous infusion for sedation in patients following abdominal aortic surgery. Thirty subjects, 50–75 yr, scheduled to undergo aortic reconstructive surgery, entered the study. Following a nitrous oxide-isoflurane-opioid anaesthetic technique, patients were randomly allocated to receive one of three loading doses (0.03, 0.06 or 0.1 mg · kg^?1) and initial infusion rates (0.5, 1.0 or 1.5 μg · kg^?1 · min^?1) of midazolam, corresponding to groups low (L), moderate (M) and high (H). The infusion of midazolam was adjusted to maintain sedation levels of “3, 4 or 5,“ which permitted eye opening in response to either verbal command or a light shoulder tap, using a seven-point scale ranging from “0” (awake, agitated) to “6” (asleep, non-responsive). Additionally, morphine was given in increments of 2.0 mg iv prn for analgesia. On the morning after surgery, midazolam was discontinued, and the tracheas were extubated when patients were awake. Blood samples were taken during, and at increasing intervals for 48 hr following discontinuation of the infusion, and analyzed by gas chromatography. The desired level of sedation was maintained during more than 94% of the infusion period in all three groups, with a maximum of three dose adjustments per patient, for treatment which lasted 16.3 ± 0.6 hr. There was, however, an increase in both the infusion rates and mean plasma concentrations from Group L to Group H (P < 0.05), which corresponded to an inverse relationship of morphine requirements during the period of sedation (P < 0.05, Group H vs Group L). Optimal midazolam infusion rates and resulting plasma concentrations at the times the infusions were discontinued (in parentheses) were as follows — Group L: 0.60 ± 0.18 μg · kg^?1 min^?1 (76 ± 32 ng · mL^?1), Group M: 0.90 ± 0.52 μg · kg^?1 · min^?1 (133 ± 71 ng · mL^?1), and Group H: 1.34 ± 0.69 μg · kg^?1 · min^?1 (206 ± 106 ng · mL^?1). Times to awakening were longer in Group H: 3.1 ± 3.4 hr, than in Group L: 1.1 ± 0.8 h, P < 0.05. Pharmacokinetic variables were found to be dose- independent over the range of infusion rates. Mean values were t_1/2β = 4.4 ± 1.5 hr, CL = 5.94 ± 1.69 mL · min^?1 · kg^?1, Vd = 3.13 ± 1.07 L · kg^?1. It is concluded that midazolam, infused between 0.6–0.9 μg · kg^?1 · min^?1, provides a stable level of sedation, when administered in conjunction with intermittent iv morphine following AAS. This sedation technique, which costs $1.65 ± 0.73 hr^?1 ($Can), is associated with rapid recovery and minimal side effects.     

Oral ondansetron decreases vomiting after tonsillectomy in children

Vomiting is a common, unpleasant aftermath of tonsillectomy in children. Intraoperative intravenous ondansetron (OND) reduces vomiting after this operation. Our doubleblind, placebocontrolled, randomized investigation studied the effect of the oral form of OND on vomiting after outpatient tonsillectomy in children. We studied 233 healthy children age 2–14 yr undergoing elective tonsillectomy. Subjects were given placebo (PLAC) or OND 0.1 mg · kg^?1 rounded off to the nearest 2 mg one hr before surgery. Anaesthesia was induced with either propofol or halothane/N₂O. Vecuronium 0.1 mg · kg^?1 was administered at the discretion of the anaesthetist. Anaesthesia was maintained with halothane/N₂O, 50 μg · kg^?1 midazolam iv and 1–1.5 mg · kg^?1 codeine im. At the end of surgery, residual neuromuscular blockade was reversed with neostigmine and atropine. All episodes of inhospital emesis were recorded by nursing staff. Rescue antiemetics in the hospital were 1 mg · kg^?1 dimenhydrinate ivfor vomiting × 2 and 50 μg · kg^?1 droperidol iv for vomiting × 4. Parents kept a diary of emesis after discharge. Postoperative pain was treated with morphine, codeine and/or acetaminophen. The two groups were similar with respect to demographic data, induction technique and anaesthesia time. Oral OND (n = 109) reduced postoperative emesis from 54% to 39%, P < 0.05. This effect was most dramatic inhospital, where 10% of the OND-patients and 30% of the PLAC-group vomited, P < 0.05. The OND-subjects required fewer rescue antiemetics, 7% vs 17%, P < 0.05. In conclusion, oral ondansetron decreased the incidence of vomiting after outpatient tonsillectomy in children.     

Intrathecal clonidine decreases propofol sedation requirements during spinal anesthesia in infants

Background: Propofol is a popular agent for providing procedural sedation in pediatric population during lumbar puncture and spinal anesthesia. Adjuvants like clonidine and fentanyl are administered intrathecally to prolong the duration of spinal anesthesia and to provide postoperative analgesia. We studied the propofol requirement after intrathecal administration of clonidine or fentanyl in infants undergoing lower abdominal surgeries. Methods: Sixty‐five ASA I infants undergoing elective lower abdominal surgery under spinal anesthesia were assigned into four groups in this prospective randomized double‐blinded study. Group B received bupivacaine based on body weight (<5 kg = 0.5 mg·kg⁻¹; 5–10 kg = 0.4 mg·kg⁻¹). Group BC received 1 μg·kg⁻¹ of clonidine with bupivacaine, group BF received 1 μg·kg⁻¹ of fentanyl with bupivacaine, and patients in group BCF received 1 μg·kg⁻¹ each of clonidine and fentanyl with bupivacaine. A bolus of 2–3 mg·kg⁻¹ of propofol bolus was administered for lumbar puncture. Sedation was assessed using a six‐point sedation score (0–5) and a five‐point reactivity score (0–4) which was based on a behavioral score. After achieving a sedation and reactivity score of 3–4, the patients were placed lateral in knee chest position and lumbar puncture performed and test drug administered. Further intraoperative sedation was maintained with an infusion of 25–50 μg·kg⁻¹·min⁻¹ of propofol infusion. Results: The mean ± sd infusion requirement of propofol decreased from 35.5 ± 4.5 in group B to 33.4 ± 5.4 μg·kg⁻¹·min⁻¹ in group BF and further decreased to 16.7 ± 6.2 μg·kg⁻¹·min⁻¹ and 14.8 ± 4.9 μg·kg⁻¹·min⁻¹ in group BC and BCF, respectively. There were no statistically significant differences between BC and BCF groups. The mean sedation and reactivity scores were higher in groups BC and BCF when compared to groups B and BF. Conclusion: Our study show that the requirement of propofol sedation reduces with intrathecal adjuvants. The reduction was significant with the addition of clonidine and clonidine–fentanyl combination as opposed to bupivacaine alone or with fentanyl. There was no significant difference in propofol infusion requirement with the use of bupivacaine alone or with fentanyl.     

Propofol or midazolam for sedation and early extubation following cardiac surgery

Purpose

The purpose of this randomized, double-blind study was to evaluate the efficacy of midazolam and propofol for postoperative sedation and early extubation following cardiac surgery.

Methods

ASA physical status II-III patients scheduled to undergo elective first-time cardiac surgery with an ejection fraction > 45% were eligible. All patients received a standardized sufentanil/isoflurane anaesthesa. Dunng cardiopulmonary bypass 100 μg · kg^?1· mm^?1 propofol was substituted for isoflurane. Upon amval in the Intensive Care Unit (ICU). patients were randomized to either 10 μg · kg · min^?1 propofol (n = 21) or 0.25 μg · kg · mm^?1 midazolam (n = 20). Infusion rates were adjusted to maintain sedation within a predetermined range (Ramsay 2–4). The infuson was terminated after four hours. Patients were weaned from mechanical ventilation and their tracheas extubated when haemodynamic stability, haemostasis, normothermia and mental orientation were confirmed. Haemodynamic measurements, artenal blood gas tensions and pulmonary function tests were recorded at specified times.

Results

There were no differences between the two groups for the time spent at each level of sedation, number of infusion rate adjustments, amount of analgesic and vasoactive drugs, times to awakening and extubation. The costs of propofol were higher than those of midazolam. There were no differences in haemodynamic values, artenal blood gas tensions and pulmonary function.

Conclusion

We conclude that midazolam and propofol are safe and effective sedative agents permitting early extubation in this selected cardiac patient population but propofol costs were higher.     

Changes in carbon dioxide tension and oxygen saturation during deep sedation for paediatric cardiac catheterization

The purpose of this observational study was to determine whether hypercarbia or oxygen desaturation occurred during our current regimens of deep sedation or general anaesthesia of infants and children undergoing cardiac catheterization. Data were gathered prospectively from 50 consecutive infants and children aged 4 months to 12 years undergoing cardiac catheterization. Several anaesthetists used the following regimens, which were not randomized: 1) propofol. 1.5–2.0 mg·kg^?1 and fentanyl 1 μg·kg^?1 IV over 2 min for induction, followed by propofol infusion of 100–150 μg·kg^?1·min^?1; 2) fentanyl 2–3 μg·kg^?1 and midazolam 0.1–0.2 mg·kg^?1 IV over 10–15 min; 3) ketamine 8 mg·kg^?1 IM, or 4) same as regimens 1 or 2, plus pancuronium, intubation and controlled ventilation. Regimens 1, 2, and 3 were associated with spontaneous ventilation through the natural airway. End-tidal carbon dioxide tension (Petco₂), Spo₂, and respiratory rate were monitored for 60 min. The three regimens employing spontaneous ventilation through the natural airway were associated with both statistically and clinically significant increases in Petco₂ and decreases in Spo₂. This raises the possibility that acute exacerbation of PAP and PVR may occur in pulmonary hypertensive patients. In contrast, Petco₂ and Spo₂ did not change significantly from baseline in the controlled ventilation group.     

Ketamine boluses with continuous low-dose fentanyl for paediatric sedation during diagnostic cardiac catheterization

During cardiac catheterization, 202 children aged 1 month to 16 yrs were sedated intravenously half an hour after oral premedication with flunitrazepam 0.1 mg·kg^?1 (maximum dose 2 mg) to maintain spontaneous breathing and stable and calm conditions for the investigation. Standard fentanyl doses for induction and maintenance were 1 μg·kg^?1 and 1 μg·kg^?1·h^?1, respectively, for all patients. Requirements for supplementary ketamine for induction and maintenance of stable sedation were studied in five age groups (≤0.5 yr, >0.5–2 yr, >2.0–5.0 yr, >5.0–10.0 yr and >10.0 yr). Ketamine doses for induction were 1.5 ± 0.1, 1.5 ± 0.1, 1.2 ± 0.1, 0.9 ± 0.1 and 0.2 ± 0.1 (mean ± SEM) mg·kg^?1 in these age groups, respectively. Ketamine requirements for maintenance of sedation were 1.9 ± 0.1, 1.7 ± 0.1, 1.4 ± 0.1, 1.1 ± 0.1 and 0.2 ± 0.1 mg·kg^?1·h^?1 in the same age groups, respectively. Age dependency of ketamine requirement was shown; the older the patient the less was the need for supplementation. Intravenous sedation with low-dose fentanyl and ketamine after flunitrazepam premedication provided favourable anaesthesia for cardiac catheterization.     

Subhypnotic propofol infusion plus dexamethasone is more effective than dexamethasone alone for the prevention of vomiting in children after tonsillectomy

Background: Postoperative vomiting (POV) is a common complication after tonsillectomy. Dexamethasone is known to decrease postsurgical vomiting. In this study, we compared the effects of dexamethasone alone to dexamethasone plus propofol on postoperative vomiting in children undergoing tonsillectomy. Methods: In a randomized double‐blinded study, we evaluated 80 healthy children, aged 4–12 years, who underwent tonsillectomy with or without adenoidectomy. After anesthesia was induced by inhalation of sevoflurane, 0.15 mg·kg^?1 dexamethasone and 2 μg·kg^?1 fentanyl was administered i.v. to all patients. The patients in the dexamethasone plus propofol group received 1 mg·kg^?1 propofol before intubation and continuously after intubation at a rate of 20 μg·kg^?1·min^?1 until the surgery was completed. Data for postoperative vomiting were grouped into the following time periods: 0–4 and 4–24 h. Data were analyzed using a Student’s t‐test and chi‐squared analysis. Results: The percentage of patients exhibiting a complete response (defined as no retching or vomiting for 24 h) increased from 37.5% in the dexamethasone‐alone group to 75% in the dexamethasone plus propofol group (P = 0.001). Twenty‐two patients (55%) in the dexamethasone‐alone and nine patients (22.5%) in the dexamethasone plus propofol groups experienced vomited during 0–4 h (P = 0.003). Eight patients in the dexamethasone‐alone group and three patients in the dexamethasone plus propofol group received ondansetron as a rescue antiemetic during the postoperative period. Conclusion: For children undergoing tonsillectomy, intraoperative subhypnotic propofol infusion combined with dexamethasone treatment provides a better prophylaxis against postoperative vomiting than does dexamethasone alone.     

Comparison of propofol-fentanyl with propofol-fentanyl-ketamine combination in pediatric patients undergoing interventional radiology procedures

Background: With an increase in the frequency of interventional radiology procedures in pediatrics, there has been a corresponding increase in demand for procedural sedation to facilitate them . The purpose of our study was to compare the frequency of adverse effects, sedation level, patient recovery characteristics in pediatric patients receiving intravenous propofol fentanyl combination with or without ketamine for interventional radiology procedures. Our main hypothesis was that the addition of ketamine would decrease propofol/fentanyl associated desaturation. Methods and materials: Sixty consenting American Society of Anesthesia physical status I–III pediatric patients undergoing interventional radiology procedures under sedation were studied according to a randomized, double‐blinded, institutional review board approved protocol. Group 1 received propofol 0.5 mg·kg^?1 + fentanyl 1 μg·kg^?1 + ketamine 0.5 mg·kg^?1, and group 2 received propofol 0.5 mg·kg^?1 + fentanyl 1 μg·kg^?1 + same volume of %0.9 NaCl intravenously. Results: While apnea was not observed in any of the groups, there were three cases (10%) in group 1, and nine cases (30%) in group 2 with oxygen desaturation (P = 0.052). In group 1, 12 (40%) patients and, in group 2, 21 (70%) patients required supplemental propofol during the procedure (P = 0.021). There was no evidence for difference between groups in terms of other side effects except nystagmus. Conclusions: In conclusion, addition of low dose ketamine to propofol‐fentanyl combination decreased the risk of desaturation and it also decreased the need for supplemental propofol dosage in pediatric patients at interventional radiology procedures.     

A comparison of pentamorphone and fentanyl in balanced anaesthesia during general surgery

The purpose of our randomized, double-blind study of 64 unpremedicated healthy patients undergoing surgical procedures with a duration of at least 60 min was to compare 0.75 μg · kg^?1 and 1 μg · kg^?1 pentamorphone with 5 μg · kg^?1 and 7.5 μg · kg^?1 fentanyl to determine which dose of opioid would reduce the requirement for isoflurane supplementation needed to maintain haemodynamic stability. At 21 points during the procedure, the haemodynamic variables of heart rate and systolic, diastolic, and mean arterial pressures were recorded. The use of isoflurane was quantified; the number of patients requiring inhaled anaesthetic, concentration peaks, MAC minutes, and duration of isoflurane use were noted. The number of equal-volume supplemental opioid analgesic doses, postoperative analgesics, occurrence of postoperative nausea, emesis, and antiemetic doses were compared. The four groups exhibited similar patient demographics, total dose of muscle relaxants, types of surgical procedures, and duration of surgery or anaesthesia. Haemodynamic variables were stable with no difference among the four study groups. The patients given pentamorphone demonstrated both delayed requirement (P < 0.05) and shorter duration (P < 0.05) of isoflurane supplementation. Patients given either 5 μg · kg^?1 or 7.5 μg · kg^?1 fentanyl needed isoflurane supplementation within 12 ± 16 min and 12 ± 17 min from induction respectively; while patients given either 0.75 μg · kg^?1 or 1 μg · kg^?1 pentamorphone did not require isoflurane supplementation for 37 ± 10 min and 43 ± 26 min respectively. In addition, the 1 μg · kg^?1 pentamorphone group had significantly (P < 0.05) lower peak isoflurane concentrations than the 5 μg · kg^?1 fentanyl study group (0.9 ± 0.5 MAC% vs 1.5 ± 0.3 MAC%). In conclusion, we found pentamorphone to be a haemodynamically stable, isofluranesparing opioid analgesic. Pentamorphone’s major advantage over fentanyl was its lower requirement for inhalation agent in a balanced anaesthesia technique.     

Intravenous sedation for children with Down's syndrome undergoing cardiac catheterization

Down's syndrome is commonly associated with cardiac malformations and sleep related upper airway obstruction. The dose response for ketamine in the presence of an infusion of fentanyl was determined in 28 consecutive children (3–51 months) with Down's syndrome and congenital heart disease during haemodynamic catheterization. The children were premedicated with flunitrazepam orally and glycopyrrolate i.v. Ventilation was continuously monitored with a capnograph. Fentanyl 1 μg·kg^?1 and 1 μg·kg^?1·h^?1 was administered in fixed doses for induction and maintenance of sedation, respectively. The mean induction and maintenance requirements of ketamine were 1.5 ± 0.5 mg·kg^?1 and 1.8 ± 0.8 mg·kg^?1·h^?1, respectively. In infants younger than 6 months, more ketamine was needed for both induction and maintenance than in older children (P < 0.005). Normoventilation without any airway manipulation could be maintained in 15 patients (54%). Respiratory difficulties were frequent: hypoventilation required temporary mask ventilation, insertion of a nasopharyngeal tube or tracheal intubation in two, seven and four children, respectively. Oral flunitrazepam premedication and intravenous sedation with low-dose fentanyl and ketamine combined with close monitoring of ventilation can be used for cardiac catheterization in children with Down's syndrome. However, the described combination of sedative drugs does not prevent the occurrence of sleep related upper airway obstruction.     

Mivacurium infusion requirements following vecuronium: different response between adults and children

The mivacurium infusion requirements following vecuronium were evaluated in 15 adults and 15 children in an open prospective clinical study. This study was undertaken to elucidate whether potentiation of effect occurred when a mivacurium infusion was administered after vecuronium was used for the facilitation of tracheal intubation. The adult patients were anaesthetized with N₂O:O₂, propofol and fentanyl, the children with halothane (1%) N₂O:O₂ Vecuronium 100 μg · kg^?1 was administered during stimulation of the ulnar nerve with train-of-four stimuli at 0.1 Hz. The force of contraction of the adductor pollicis was recorded. Upon recovery of the twitch response from vecuronium, a mivacurium infusion was started at 4 μg · kg^?1 · min^?1, thereafter adjustments were made to maintain the first twitch of the train-of-four (T₁ at 1–10% of control. The mean (±SE) initial infusion requirements in children of mivacurium was 4.3 (0.4) μg · kg^?1 · min^?1 which increased linearly (P < 0.001) over the next 90 min to 10 μg · kg^?1 · min^?1. In adults the infusion requirement was lower than in children and remained at approximately 3 μg · kg^?1 · min^?1 over the next 75 min. At the end of the surgical procedure, the children recovered faster than the adults with no child requiring reversal. Because of prolonged recovery (>20 min), seven adults required reversal with 15–70 μg · kg^?1 neostigmine. Mivacurium infusion requirements following vecuronium are higher in children than adults. Potentiation of the effects of mivacurium were seen when vecuronium preceeded mivacurium. This potentiation of effect lasted longer in adults than in children.     

Oral clonidine premedication reduces vomiting in children after strabismus surgery

This is a prospective randomized double-blind trial conducted to determine whether preoperative orally administered clonidine causes or potentiates postoperative vomiting in 140 children (3–12 yr) undergoing strabismus surgery. They were all inpatients and classified randomly into four groups (n = 35 each); placebo (control), diazepam 0.4 mg · kg^?1, clonidine 2 μg · kg^?1, and clonidine 4 μg · kg^?1. These agents were administered 93–112 min (mean: 100 min) before the anticipated time of induction of anaesthesia. All children received inhalational anaesthesia with halothane and nitrous oxide in oxygen.’ Muscle relaxation in all patients was obtained with vecuronium and residual neuromuscular blockade was antagonized with neostigmine and atropine before tracheal extubation. Diclofenac suppository was prescribed to prevent postoperative pain. No opioids or postoperative antiemetics were administered. All children remained in hospital for two days postoperatively. The incidence and frequency of vomiting were compared in the groups with Kruskall-Wallis Rank test. Clonidine 4 μg · kg^?1 caused a lower incidence and frequency of vomiting than did placebo and diazepam (incidence and frequency: 11% and 1,37% and 3, and 34% and 2 in clonidine 4 μg · kg^?1, placebo, and diazepam, respectively; P < 0.05 for clonidine 4 μg · kg^?1 vs placebo and diazepam). However, lowdose clonidine was ineffective. These data suggest that preanaesthetic medication with clonidine 4 μg · kg^?1 may be useful for preventing emesis following strabismus surgery. This property of clonidine indicates that it may be superior to other sedative premedicants such as diazepam and midazolam.