Incidence and therapy of midazolam induced hiccups in paediatric anaesthesia

Midazolam-Induced Hiccups Reversed by Flumazenil: A Case Report

Hiccups are a common phenomenon experienced by many people and are usually short-lived with spontaneous resolution of symptoms. Certain anesthetic medications have been associated with the development of hiccups, though the underlying pathophysiology and reflex arcs remain poorly understood. We describe a patient who developed hiccups lasting 9 days following an orthopedic surgery and again developed hiccups during a subsequent surgery after only having received midazolam; flumazenil administration led to sustained cessation of his hiccup symptoms immediately.

Perspectives on the Medical, Quality of Life, and Economic Consequences of Hiccups

PURPOSE OF REVIEW

Singultus or hiccups (HU) is a common, usually temporary, event. Its potentially serious consequences are often overlooked. This review explores published evidence describing HU burden (clinical, economic, and quality of life [QoL] consequences) across patient populations.

RECENT FINDINGS

Literature review identified 81 articles (including 57 individual case reports). We extracted relevant information to better understand the burden of HU and to identify knowledge gaps for future study. HU are physiologic events that can complicate existing medical conditions and treatments regardless of duration. Relatively short episodes can have devastating consequences in patients who have pre-existing conditions. HU appear to impact physical and psychological health, diminish QoL, increase healthcare resource use, and increase costs. A better understanding of HU burden is needed.

Intraoperative Laryngeal Mask Airway-Related Hiccup: An Overview

Hiccup is an involuntary contraction of the diaphragm and intercostal muscles resulting in sudden inspiration and closure of the glottis. The presence of hiccup in the perioperative period can be a challenging problem. Sudden movements of the patient from hiccups can interfere preoperative diagnostic procedures, intraoperative hiccup may delay the beginning of surgery, interfere with the surgical process, and affect intraoperative monitoring, and postoperative hiccup may affect would healing and hemodynamic stability. Hiccup can lead to have increased aspiration risk. Hiccup are is an incompletely understood phenomenon with multiple etiologies. Intraoperative hiccup related to laryngeal mask airway placement has been reported, and it presents unique challenges in diagnosis and management. Both pharmacological and non-pharmacological interventions have been utilized with various level of success. All treatment strategies are primarily aimed at interrupting the hiccup reflex arc.

Safety and Efficacy of 3 Pediatric Midazolam Moderate Sedation Regimens

Our aim was to characterize effectiveness and complications in children receiving oral midazolam alone, nasal midazolam alone, or oral midazolam with other sedatives. Children received oral midazolam alone, nasal midazolam, or oral midazolam in combination with other sedative medications. All subjects received a presedation history and physical examination and were sedated per protocol by any of 28 resident providers under attending supervision. Sedations were rated for success and complications by clinicians. Postoperative complications were assessed by trained staff up to 48 hours postoperatively. Seven hundred and one encounters, completed over 24 months, yielded 650 usable sedations. The majority of children were healthy (469; 68.2%) and 86% (532) weighed between 10 and 25 kg. Sedations were deemed successful in about 80% of cases. Planned treatment was completed in over 85% of encounters. Oral midazolam alone yielded the best behavior. Physical assessment factors of behavior and age were correlated (P = .035) with effectiveness. Hiccups and a positive medical history were significantly related (P = .049). Side effects of either nausea/vomiting, dysphoria, or hiccups occurred in less than 10% of cases. All 3 regimens were effective with minimal postoperative complications.

Systemic review: the pathogenesis and pharmacological treatment of hiccups

BACKGROUND

Hiccups are familiar to everyone, but remain poorly understood. Acute hiccups can often be terminated by physical manoeuvres. In contrast, persistent and intractable hiccups that continue for days or months are rare, but can be distressing and difficult to treat.

AIM

To review the management of hiccups, including a systematic review of reported efficacy and safety of pharmacological treatments.

METHODS

Available articles were identified using three electronic databases in addition to hand searching of published articles. Inclusion criteria were any reports of pharmaceutical therapy of 'hiccup(s)', 'hiccough(s)' or 'singultus' in English or German.

RESULTS

Treatment of 341 patients with persistent or intractable hiccups was reported in 15 published studies. Management was most effective when directed at the underlying condition. An empirical trial of anti-reflux therapy may be appropriate. If the underlying cause is not known or not treatable, then a range of pharmacological agents may provide benefit; however, systematic review revealed no adequately powered, well-designed trials of treatment. The use of baclofen and metoclopramide are supported by small randomised, placebo-controlled trials. Observational data suggest that gabapentin and chlorpromazine are also effective. Baclofen and gabapentin are less likely than standard neuroleptic agents to cause side effects during long-term therapy.

CONCLUSIONS

This systematic review revealed no high quality data on which to base treatment recommendations. Based on limited efficacy and safety data, baclofen and gabapentin may be considered as first line therapy for persistent and intractable hiccups, with metoclopramide and chlorpromazine in reserve.

Success rate of IR midazolam sedation in combination with C-CLAD in pediatric dental patients-a prospective observational study

Objective. To evaluate the success rate of intra-rectal (IR) midazolam in combination with nitrous oxide/oxygen (N₂O) sedation in young uncooperative dental patients when the local anesthesia is delivered by a computerized controlled local anesthetic delivery (C-CLAD).

Study Design. This observational study consisted of 219 uncooperative children (age: 4.3 ± 1.69 y) who received IR midazolam (0.4 mg/kg) and N₂O to complete their dental treatment. Measured variables included: child’s pain disruptive behavior during delivery of anesthesia by C-CLAD (CHEOP Scale), child behavior during treatment (Houpt scale), dental procedure performed, and side effects that appeared during treatment.

Results. There was a high level of cooperation (mean score: 6.69 ± 2.1) during administration of local anesthesia. Good-to-excellent behavior was shown by 87% of the children during treatment. Planned treatment was completed by 184 (92%) patients. No statistically significant changes were noticed in the oxygen saturation levels before and after treatment. Children with side effects included 3 (1.3%) with nistagmus, 5 (2.3%) with diplopia, and 18 (8.2%) with hiccups. Three consecutive sedations decreased the overall behavior score by 5.7% compared to the first appointment (p < .05).

Conclusions. IR midazolam-N₂O sedation in combination with C-CLAD is very effective for delivery of dental treatment to young uncooperative children.

Transient hiccups associated with oral dexamethasone

Hiccups, or singulata (hiccup is singultus), are commonly experienced by most people at one time or another and are usually brief and self-limiting. Although pharmacotherapeutic agents are not generally considered causal in the etiology of hiccups, many clinicians empirically associate episodic hiccups in their patients as being drug induced. The two classes of drugs most often cited as causing hiccups are corticosteroids and benzodiazepines. This report involved a patient who was given preoperative dexamethasone and developed hiccups before anesthesia and surgery commenced. He at no time was in distress, and the surgical procedure was completed without complication. By the second postsurgical day his hiccups were resolved completely. Although the association may be anecdotal, many clinicians consider hiccups a potential side effect of steroid therapy, especially high doses of steroids. Of interest in this case is the relatively low dose of corticosteroid used, albeit apparently linked to his hiccups. Practitioners should be aware of this potential condition.

Comparative evaluation of midazolam and clonidine as pediatric oral premedication

BACKGROUND

Clonidine provides many desirable effects like sedation, analgesia, anxiolysis, and hemodynamic stability and these properties make it a potentially useful anesthetic premedication in the pediatric settings. The aim of this study was to compare oral midazolam (0.5 mg/kg), which is considered gold standard with oral clonidine (5 mcg/kg) as a premedication in pediatric patients.

MATERIALS AND METHODS

Sixty children classified as American Society of Anesthesiologists physical status I, aged between 2 and 12, who were scheduled to undergo an elective surgery, were enrolled for a prospective, randomized, and double blind controlled trial. They received either oral midazolam (Group M) or oral clonidine (Group C) 60 minutes before induction of anesthesia and were submitted to an evaluation of anxiety and sedation scores. We also evaluated secondary outcomes such as palatability, parental separation, effect on hemodynamic status, co-operation during venipuncture and facemask application, postoperative analgesic requirement, and recovery profile.

RESULTS

Oral midazolam had better efficacy in the preoperative period as sedative and anxiolytic (P < 0.001), allowed better cooperation during venipuncture and facemask application (P < 0.001), whereas, oral clonidine provided better palatability (P < 0.001), parental satisfaction (P < 0.001), stable perioperative hemodynamics (P < 0.001), better postoperative analgesia (P < 0.001), and night sleep pattern (P < 0.05) without any noticeable side effects (P > 0.05).

CONCLUSION

We conclude that under the conditions of this study, oral midazolam is a better medication than clonidine in children in preoperative period while clonidine is a better medication postoperatively with added advantage of palatability, hemodynamic stability, and no significant side effects.

Sedation-associated hiccups in adults undergoing gastrointestinal endoscopy and colonoscopy

AIM: To investigate whether the incidence of hiccups in patients undergoing esophagogastroduodenoscopy (EGD) or same-day bidirectional endoscopy (EGD and colonoscopy; BDE) with sedation is different from those without sedation in terms of quantity, duration and typical onset time.

METHODS: Consecutive patients scheduled for elective EGD or same-day BDE at the gastrointestinal endoscopy unit or the health examination center were allocated to two groups: EGD without sedation (Group A) and BDE with sedation (Group B). The use of sedation was based on the patients’ request. Anesthesiologists participated in this study by administrating sedative drugs as usual. A single experienced gastroenterologist performed both the EGD and the colonoscopic examinations for all the patients. The incidence, duration and onset time of hiccups were measured in both groups. In addition, the association between clinical variables and hiccups were analyzed.

RESULTS: A total of 435 patients were enrolled in the study. The incidences of hiccups in the patients with and without sedation were significantly different (20.5% and 5.1%, respectively). The use of sedation for patients undergoing endoscopy was still significantly associated with an increased risk of hiccups (adjusted odds ratio: 8.79, P < 0.001) after adjustment. The incidence of hiccups in males under sedation was high (67.4%). The sedated patients who received 2 mg midazolam developed hiccups more frequently compared to those receiving 1 mg midazolam (P = 0.0028). The patients with the diagnosis of gastroesophageal reflux disease (GERD) were prone to develop hiccups (P = 0.018).

CONCLUSION: Male patients undergoing EGD or BDE with sedation are significantly more likely to suffer from hiccups compared to those without sedation. Midazolam was significantly associated with an increased risk of hiccups. Furthermore, patients with GERD are prone to develop hiccups.

Persistent hiccups associated with epidural ropivacaine in a newborn

OBJECTIVE

To report a case of persistent hiccups associated with epidural ropivacaine in a newborn infant.

CASE SUMMARY

A term female infant (3.05 kg) received epidural ropivacaine for pain control during and after an operative procedure to correct a tracheoesophageal fistula. Three intermittent doses of ropivacaine were administered during the operative period (total dose 2.29 mg/kg) followed by a continuous epidural (caudal) infusion (0.1% ropivacaine; initial dose 0.23 mg/kg/h plus fentanyl 0.46 μg/kg/h). The infant was extubated in the recovery area and transferred to the intensive care unit. Within hours of transfer, she developed persistent hiccups. The epidural infusion was titrated for pain control, up to 0.32 mg/kg/h (ropivacaine). The hiccup frequency increased to every 10-30 seconds, with the patient appearing hypotonic with lip trembling and intermittent tongue fasciculation. An electroencephalogram did not show any epileptiform activity or focal features consistent with seizure activity. The epidural infusion was reduced to 0.26 mg/kg/h (ropivacaine), with dramatic improvement in hiccups and tone. The infusion was discontinued and complete resolution of hiccups was observed.

DISCUSSION

Ropivacaine is commonly used for infiltration anesthesia and peripheral and epidural block anesthesia. Use of the Naranjo probability scale determined that our patient's hiccups were probably caused by ropivacaine. To our knowledge, this is the first report of persistent hiccups associated with epidural ropivacaine.

CONCLUSIONS

Clinicians should consider the potential of neurotoxicity, manifested as persistent hiccups, when epidural ropivacaine is administered to young infants.

Premedication in children: a comparison of oral midazolam and oral clonidine

BACKGROUND

Oral premedication is widely used in pediatric anesthesia to reduce preoperative anxiety and ensure smooth induction. Midazolam is currently the most commonly used premedicant, but good results have also been reported with clonidine. The aim of the present study was to compare clinical effects of oral midazolam and oral clonidine.

METHODS

We performed a prospective open study in 64 children who were randomly assigned to receive either oral midazolam 0.5 mg.kg (-1) (group M) or oral clonidine 4 microg.kg (-1) (group C) prior to mask induction. Drug acceptance, preoperative sedation and anxiolysis, quality of mask acceptance, recovery profile and parental satisfaction were evaluated.

RESULTS

The taste of oral clonidine was judged as significantly better; 14% of children rejected oral midazolam. Onset of sedation was significantly faster after premedication with midazolam (30+/-13.1 min) than with clonidine (38.5+/-14.6 min), but level of sedation was significantly better after premedication with clonidine. Quality of mask induction was equally successful in both groups. A steal-induction was performed in 66% of patients of group C, but none in group M. We observed a trend towards an increased incidence of emergence agitation after premedication with midazolam. Parental satisfaction was significantly higher in group C.

CONCLUSIONS

In this study, premedication with oral clonidine appeared to be superior to oral midazolam. Quality of mask acceptance was comparable between groups, but oral clonidine was better accepted by the child, produced more effective preoperative sedation, showed a trend towards better recovery from anesthesia and had a higher degree of parental satisfaction.

Clonidine: an alternative to benzodiazepines for premedication in children

PURPOSE OF REVIEW

The aim of this review is to summarize the use of clonidine for paediatric premedication and to make a comparison with benzodiazepines. A routine clonidine premedication protocol is also presented.

RECENT FINDINGS

In the US 50% of young children undergoing surgery receive premedication and midazolam is the most frequently used drug. The number of trials that compare midazolam with active controls are few and this premedicant is not adequately validated. Clonidine is still used as premedication in a small number of centres but the literature on paediatric use of clonidine is steadily growing. A recent review article has concluded that the use of clonidine does enhance the quality of perioperative management in infants and children and more recent publications support the use of clonidine for premedication. Its effect on the circulation is mild but routine atropine administration is recommended. Contraindications to the use of clonidine are few. Apart from a general overview on the effects of clonidine this article will also summarise the published trials that have compared clonidine with benzodiazepines for premedication in children.

SUMMARY

Midazolam the most commonly used drug for paediatric premedication worldwide. Despite having a number of beneficial effects it is far from an ideal premedicant, especially concerning its effect on cognition/amnesia, confusion and long-term behavioural disturbances. Clonidine lacks the majority of the negative effects associated with midazolam and is associated with a number of beneficial perioperative effects. Our clinical experience of replacing midazolam with clonidine as premedicant in children, including also outpatients, has been favourable.

Clonidine in paediatric anaesthesia: review of the literature and comparison with benzodiazepines for premedication

BACKGROUND

Children undergoing anaesthesia and surgery can experience significant anxiety and distress during the peri-operative period, but whether routine premedication is necessary is currently debated. Benzodiazepines are the most frequently used drugs as premedication in paediatric anaesthesia. In the US, 50% of young children undergoing surgery receive premedication and midazolam is the most frequently used drug in this context (1). Nishina and coworkers (2) concluded in a review article in 1999 that clonidine, administered via an oral, rectal, or caudal route, is a promising adjunct to anaesthetics and analgesics to enhance quality of peri-operative management in infants and children. Later publications also support the use of clonidine for premedication (3-6). The aim of this communication is to review the use of clonidine in paediatric anaesthesia and to propose clonidine as a promising alternative to midazolam. Clonidine is associated with a number of beneficial effects in the context ofanaesthesia both in adults and children. Why clonidine is not routinely use in clinical practice despite the massive publication list is to a large extent due to the lack of marketing efforts from the pharmaceutical industry since multiplegeneric preparations are now readily available on most markets. Midazolam is also associated with a number of beneficial effects, but is far from an ideal premedicant in children, especially with regards to the amnesia, confusion and long term behavioural disturbances. Clonidine has contrary to midazolam no effect on respiration. We believe that clonidine is a good alternative to midazolam as premedication in infants and children.

[Benzodiazepine and hiccup: three case reports]

Hiccup is a sudden contraction of the inspiratory muscles, followed by an abrupt closure of the glottis, thus producing a characteristic sound. In the literature, some drugs have been reported to induce hiccup. We discuss three case reports after administration of benzodiazepine to healthy young subjects during two clinical trials. In the first study (a bioequivalence trial of two forms of lormetazepam, tablets and oral solution), 12 subjects were included in an open controlled crossover study with two periods separated by a washout of 7 days. Two subjects presented with hiccup after administration of lormetazepam (2mg oral solution). The symptom resolved in 10 and 40 minutes, respectively. In one subject, rechallenge with a tablet of lormetazepam was positive. The aim of the second study was to assess the effect of sleep deprivation and lorazepam-induced sedation on saccadic eye movements in 12 healthy subjects. Hiccup occurred in one subject 3h 15 after administration of a single oral dose of lorazepam (2mg) and resolved in 45 minutes. All cases were evaluated according to the French imputation method. These observations are discussed with regard to the drug classes mentioned most frequently in the literature.

Factors determining the duration of tracheal intubation in cardiac surgery: a single-centre sequential patient audit

BACKGROUND AND OBJECTIVE

The study was designed to identify those factors associated with early tracheal extubation following cardiac surgery. Previous studies have tended to concentrate on surgery for coronary artery bypass or on other selected cohorts.

METHODS

Sequential cohort analysis of 296 unselected adult cardiac surgery patients was performed over 3 months.

RESULTS

In total, 39% of all patients were extubated within 6 h, 89% within 24 h and 95% within 48 h. Delayed extubation (>6 h after surgery) appeared unrelated to age, gender, body mass index, a previous pattern of angina or myocardial infarction, diabetes, preoperative atrial fibrillation, and preoperative cardiovascular assessment, as well as other factors. Delayed tracheal extubation was associated with poor left ventricular, renal and pulmonary function, a high Euroscore, as well as the type, duration and urgency of surgery. Early extubation (<6 h) was not associated with a reduced length of stay in either the intensive care unit or in hospital compared with patients who were extubated between 6 and 24 h. In these groups, it is presumed that organizational and not clinical factors appear to be responsible for a delay in discharge from intensive care. Patients who were extubated after 24 h had a longer duration of hospital stay and a greater incidence of postoperative complications. Postoperative complications were not adversely affected by early tracheal extubation.

CONCLUSIONS

In an unselected sequential cohort, both patient- and surgery-specific factors may be influential in determining the duration of postoperative ventilation of the lungs following cardiac surgery. In view of the changing nature of the surgical population, regular re-evaluation is useful in reassessing performance.

Injection pain of rocuronium and vecuronium is evoked by direct activation of nociceptive nerve endings

BACKGROUND AND OBJECTIVE

Rocuronium and, to a lesser extent, vecuronium can induce burning sensations associated with withdrawal reactions during administration. Dermal microdialysis in human and electrophysiological recordings of nociceptors in mouse skin were used to elucidate the underlying mechanisms of pain induction.

METHODS

Microdialysis catheters were inserted intradermally into the forearm of 10 volunteers and were perfused with two different concentrations of rocuronium and vecuronium (1 and 10 mg mL(-1)) or a control. Dialysis samples were taken every 15 min and analysed for protein, histamine, tryptase and bradykinin content. Pain intensity was rated on a numerical scale of 0-10. In a parallel design, activation of cutaneous nociceptors was assessed directly in a skin-nerve in vitro preparation of the mouse hind paw. The receptive fields of identified single C-nociceptors (n = 12) were superfused with rocuronium or vecuronium solutions (10 mg mL(-1)) at physiological pH.

RESULTS

In accordance with clinical observations, microdialysis of rocuronium (10 mg mL(-1)) induced sharp burning pain (NRS 4.1 +/- 1.8), whereas vecuronium given in the usual clinical concentration (1 mg mL(-1)) induced only minor pain sensations (NRS 0.6 +/- 1.3). At equimolar concentrations, pain sensation and concomitant mediator release evoked by both drugs were similar. No correlations were found between pain rating and mediator release. In the in vitro preparation, C-fibres showed a consistent excitatory response with rapid onset after stimulation with vecuronium as well as rocuronium (differences not significant).

CONCLUSIONS

The algogenic effect of aminosteroidal neuromuscular blocking drugs can be attributed to a direct activation of C-nociceptors.

Anaesthetic strategies to reduce perioperative blood loss in paediatric surgery

In adults, a number of measures to reduce perioperative blood loss have been established. These techniques serve to reduce patients' exposure to homologous blood. Most adults are concerned with this issue especially since many patients became infected with human immunodeficiency virus (HIV) during the 1980s through exposure to blood components. While blood-saving strategies are widely used in adults, they are mostly neglected in infants. However, it is these young patients with their whole life in front of them who, it could be argued, would benefit especially from any potentially avoidable infection (HIV, hepatitis, etc.) or immunological complications. In infants and small children, these blood-sparing techniques may not be as effective as in adults and technical limitations may prevent their application. However, some of these measures can be used and may serve to prevent or reduce exposure to homologous blood. In the following review, blood-saving techniques established in adults are described and their applicability for paediatric patients discussed.

Effects of propofol on the systolic and diastolic performance of the postischaemic, reperfused myocardium in rabbits

BACKGROUND AND OBJECTIVE

The effect of propofol on myocardial dysfunction during ischaemia and reperfusion is controversial yet important because of its frequent use in cardiac anaesthesia. Although animal studies suggest a free radical-scavenging potential, the cardioprotective properties of propofol have not been demonstrated consistently in vivo. Previous studies focused on systolic function while diastolic function may be a more sensitive marker of ischaemic injury. The main aim was to document the effect of propofol on diastolic function in isolated, blood perfused rabbit hearts subjected to moderate global ischaemia and reperfusion.

METHODS

Propofol 168 micromol L(-1), or the equivalent of its vehicle, Intralipid, was administered to 34 paced parabiotic Langendorff blood-perfused isolated rabbit hearts before and after 30 min of global normothermic ischaemia. Recovery of systolic function was quantified with the maximum rate of rise of left ventricular pressure. Diastolic performance was assessed using the time constant of the decline in left ventricular pressure (tau) and chamber stiffness (VdP/dV at 12 mmHg).

RESULTS

Recovery of systolic function during reperfusion was comparable in the two groups. There was no difference in left ventricular pressure between the two groups at any time during the experiments. Chamber stiffness increased significantly during ischaemia and reperfusion in the control group (from 34 +/- 9 to 54 +/- 8 mmHg during ischaemia, and 43 +/- 5 mmHg after 30 min reperfusion; mean +/-95% confidence interval) but not in the propofol-treated group (29 +/- 5, 36 +/- 8 and 30 +/- 8 at baseline, ischaemia and 30 min reperfusion, respectively).

CONCLUSIONS

Propofol has no protective effect on active relaxation or on systolic function in the present model, but it reduces ischaemic and postischaemic chamber stiffness.

Effects of bupivacaine used with sevoflurane on the rhythm and contractility in the isolated rat heart

BACKGROUND AND OBJECTIVE

The effects of sevoflurane on bupivacaine cardiotoxicity are mainly attributed to systemic effects. The purpose of this study was to investigate the direct myocardial effects of sevoflurane on bupivacaine toxicity.

METHODS

Hearts of 30 Wistar albino rats were isolated and mounted on a Langendorff apparatus perfused by modified Tyrode solution. Experimental groups were: a sevoflurane group (Group S, n = 10)--following baseline and 20 min (Stage 1) recordings, sevoflurane was added in doses of 1.4% (1 MAC) and 2.8% (2 MAC). In the two bupivacaine groups, bupivacaine 5 micromol (Group B5, n = 10) and bupivacaine 10 micromol (Group B10, n = 10) was added to the solution at Stage 1, and sevoflurane was added to the system as in Group S. Haemodynamic variables, i.e. heart rate, PR interval, QRS duration, left ventricular systolic pressure, contractility (+dp/dtmax), relaxation, time to reach peak systolic pressure, change in left ventricular diastolic pressure from baseline, and rate-pressure product were recorded.

RESULTS

In Group S, there was no change in cardiac rhythm. In bupivacaine groups, severe rhythm disturbances occurred and both the PR intervals and QRS complexes were prolonged significantly. All contractility variables deteriorated and the rate-pressure product decreased by 67-90% with the addition of bupivacaine. In all groups, 2 MAC sevoflurane lowered +dp/dtmax further.

CONCLUSIONS

Sevoflurane does not have any untoward effect on bupivacaine-induced cardiotoxicity in clinically relevant doses in the isolated rat heart.

Effect of the neuronal nitric oxide synthase inhibitor 7-nitroindazole on the righting reflex ED50 and minimum alveolar concentration during sevoflurane anaesthesia in rats

BACKGROUND AND OBJECTIVE

The aim was to determine the effect of acute and chronic administration of 7-nitroindazole, a selective neuronal nitric oxide synthase inhibitor, on the righting reflex ED50 and the minimum alveolar concentration during sevoflurane anaesthesia in rats.

METHODS

7-Nitroindazole was acutely (0, 50 and 100 mg kg(-1)) and chronically (0 and 150 mg kg(-1) day(-1), 4 days) administered to rats. After the preparation, the minimum alveolar concentration and the righting reflex ED50 were measured. The concentration of cGMP in the brain, cerebellum and spinal cord was also measured.

RESULTS

Acute administration reduced the minimum alveolar concentration (50 mg kg(-1), 58.8% (95% CI: 50.3-67.3%) of the baseline value, P < 0.01; 100 mg kg(-1), 55.8 (46.9-64.7), P < 0.01) and the righting reflex ED50 (50 mg kg(-1), 27.2 (17.2-37.2), P < 0.01; 100 mg kg(-1), 14.3 (6.6-22.0), P < 0.01). Chronic administration did not reduce the minimum alveolar concentration; however, it reduced the righting reflex ED50 (65.3 (52.9-77.7), P < 0.01). Overall, the reduction in minimum alveolar concentration in the acute and chronic protocol did not correlate with that of the righting reflex ED50. 7-Nitroindazole (100 mg kg(-1), acute) reduced the cGMP concentration within the cerebellum by 55.4%; however, it did not decrease concentrations in the brain or spinal cord.

CONCLUSIONS

Different mechanisms are responsible for the observed alterations to the minimum alveolar concentration and the righting reflex ED50 following treatment with 7-nitroindazole. The nitric oxide-cGMP pathway might play a less important role in the determination of minimum alveolar concentration than the righting reflex ED50.

Suprascapular nerve block or a piroxicam patch for shoulder tip pain after day case laparoscopic surgery

BACKGROUND AND OBJECTIVE

The reported incidence of shoulder tip pain following laparoscopic surgery varies from 35 to 63%. This study evaluated the analgesic efficacy of either performing a prophylactic suprascapular nerve block with bupivacaine or applying a piroxicam patch to the skin over both shoulders for the relief of shoulder tip pain after laparoscopy.

METHODS

Sixty healthy informed female patients were randomly assigned to one of three groups: (a) a control group (n = 20), no treatment; (b) a suprascapular nerve block group (n = 20) in which a bilateral suprascapular nerve block was performed before induction of anaesthesia with 5 mL 0.5% bupivacaine with epinephrine; and (c) a piroxicam patch group (n = 20) in which a 48 mg piroxicam patch on the skin of each shoulder was applied before induction of anaesthesia. All patients received a total intravenous anaesthesia technique with propofol, fentanyl and vecuronium. Shoulder tip and wound pain were recorded on a visual analogue pain scale at five time intervals for 24 h after surgery.

RESULTS

A total of 80% of patients in the control group, 75% in the suprascapular nerve block group and 45% in the piroxicam patch group complained of shoulder tip pain during the recording period (P < 0.05). The scores for shoulder tip pain in the piroxicam patch group were significantly lower compared with the control group at 3, 6 and 12 h, and compared with the suprascapular nerve block group at 6 and 12 h. The need for analgesics was also significantly lower in the piroxicam patch group compared with the other two groups.

CONCLUSIONS

Prophylactic piroxicam patches are effective and safe for the relief of shoulder tip pain after laparoscopy. Bilateral suprascapular nerve block is not effective in this setting.

Treatment of hiccup during general anaesthesia or sedation: a qualitative systematic review

BACKGROUND AND OBJECTIVE

Acute hiccup is a minor complication that can occur during sedation or general anaesthesia. The disorder can disturb the surgical field, might interfere with lung ventilation or could hamper diagnostic procedures. The objective was to perform a systematic search for interventions aimed at treating hiccup occurring during anaesthesia or sedation.

METHODS

A systematic search for reports describing interventions to treat hiccup in conjunction with anaesthesia was carried out (MEDLINE, EMBASE, Cochrane-Library, manual screening of reference lists and review articles, up to December 2001). Search terms were 'hiccup', 'singultus' or 'hiccough'.

RESULTS

Twenty-six reports involving approximately 581 patients focused on hiccup remedies in the anaesthesia setting. Only one report was substantiated by a randomized controlled trial. This investigated methylphenidate 10 mg intravenously in 51 patients, which did not show a beneficial effect compared with placebo. Hiccup was a self-limiting phenomenon. Case series and case reports focused on various systemically applied drugs in 12 reports, stimulating techniques (e.g. pharyngeal stimulation) in seven, topical applied remedies (e.g. intranasal ice-cold water) in four, and ventilation techniques (e.g. continuous positive pressure ventilation) in two.

CONCLUSIONS

A large variety of interventions have been proposed for the treatment of hiccup during anaesthesia and sedation. However, perioperative treatment is still based on empirical findings and no treatment is 'evidence-based'. Thus, no valid recommendations for the treatment of hiccup can be derived. Uncontrolled observations are inadequate to establish treatment efficacy.

Adverse effects of sedatives in children

The application of sedation/analgesia in paediatric patients is rapidly expanding as less invasive, non-operative techniques of diagnosis and treatment are applied to the paediatric population. Medical providers who are asked to provide sedation may include radiologists, paediatricians, nurses and emergency physicians, as well as anaesthesiologists and intensive care physicians. At the same time, the range of drugs used in these settings has expanded considerably. As there is no single drug fulfilling the criteria for the ideal sedative (rapid-onset, rapid recovery, no adverse effects, immobility appropriate to procedure being performed), multiple drugs may be used in combination. It is imperative that practitioners using drugs for sedation/analgesia in children be aware of the adverse effect profile(s) of these drugs, both individually and in combination. The purpose of this review is to describe the adverse effects of sedative and reversal agents currently used in paediatric sedation/analgesia.

Pharmacokinetics and pharmacodynamics of the new propofol prodrug GPI 15715 in rats

BACKGROUND AND OBJECTIVE

We studied the pharmacokinetics and pharmacodynamics of GPI 15715 (Aquavan injection), a new water-soluble prodrug metabolized to propofol by hydrolysis.

METHODS

Nine adult male Sprague-Dawley rats (398 +/- 31 g) received a bolus dose of 40 mg GPI 15715. The plasma concentrations of GPI 15715 and propofol were determined from arterial blood samples, and the pharmacokinetics of both compounds were investigated using compartment models whereby the elimination from the central compartment of GPI 15715 was used as drug input for the central compartment of propofol. Pharmacodynamics were assessed using the median frequency of the EEG power spectrum.

RESULTS

A maximum propofol concentration of 7.1 +/- 1.7 microg mL(-1) was reached 3.7 +/- 0.2 min after bolus administration. Pharmacokinetics were best described by two-compartment models. GPI 15715 showed a short half-life (2.9 +/- 0.2 and 23.9 +/- 9.9 min), an elimination rate constant of 0.18 +/- 0.01 min(-1) and a central volume of distribution of 0.25 +/- 0.02 L kg(-1). For propofol, the half-life was 1.9 +/- 0.1 and 45 +/- 7 min, the elimination rate constant was 0.15 +/- 0.02 min(-1) and the central volume of distribution was 2.3 +/- 0.6 L kg(-1). The maximum effect on the electroencephalogram (EEG)--EEG suppression for >4 s--occurred 6.5 +/- 1.2 min after bolus administration and baseline values of the EEG median frequency were regained 30 min later. The EEG effect could be described by a sigmoid Emax model including an effect compartment (E0 = 16.9 +/- 7.9 Hz, EC50 = 2.6 +/- 0.8 microg mL(-1), ke0 = 0.35 +/- 0.04 min(-1)).

CONCLUSIONS

Compared with known propofol formulations, propofol from GPI 15715 showed a longer half-life, an increased volume of distribution, a delayed onset, a sustained duration of action and a greater potency with respect to concentration.

High-affinity block of voltage-operated rat IIA neuronal sodium channels by 2,6 di-tert-butylphenol, a propofol analogue

BACKGROUND AND OBJECTIVE

Propofol is a phenol derivative (2,6 di-isopropylphenol) with a unique effect profile including activating effects on GABA(A) and blocking effects on voltage-operated sodium channels. If the substituents in the 2- and the 6-positions are replaced by tert-butyl groups, the resulting phenol derivative, 2,6 di-tert-butylphenol, despite being a close structural propofol analogue, completely lacks GABA(A) receptor effects. The aim of this in vitro study was to investigate the effects of 2,6 di-tert-butylphenol on voltage-operated neuronal sodium channels in order to determine whether and, if so, how these structural changes alter the sodium channel-blocking effect seen with propofol.

METHODS

Whole-cell sodium inward currents through heterologously expressed rat type IIA sodium channels were recorded in the absence and presence of definite concentrations of 2,6 di-tert-butylphenol and propofol.

RESULTS

When applied at concentrations > or = 30 micromol, 2,6 di-tert-butylphenol completely and irreversibly blocked sodium inward currents. The blockade equilibrium time was about 2 min. A partial washout was possible only if the application was stopped before the equilibrium of the blockade was achieved.

CONCLUSIONS

2,6 Di-tert-butylphenol exerts a high-affinity block of neuronal sodium channels. Apparently, the slight structural differences of 2,6 di-tert-butylphenol in comparison with propofol--which account for the lack of GABA(A) receptor effects--enhance its voltage-operated sodium channel-blocking effects. As 2,6 di-tert-butylphenol is much more potent than most sodium channel blockers in clinical use, it might be of interest in the development of local anaesthetics.

Effects of rolipram, pimobendan and zaprinast on ischaemia-induced dysrhythmias and on ventricular cyclic nucleotide content in the anaesthetized rat

BACKGROUND AND OBJECTIVE

This study was designed to compare the haemodynamic, electrophysiological and pharmacodynamic effects of three selective inhibitors of the different isoenzyme forms of phosphodiesterase (PDE) on ischaemia-induced dysrhythmias in the anaesthetized rat. The drugs used were pimobendan, a selective PDE III inhibitor, rolipram, a selective PDE IV inhibitor, and zaprinast, a selective PDE V inhibitor.

METHODS

The coronary artery was occluded 15 min after commencing drug administration, and myocardial ischaemia was maintained for 30 min during which the heart rate and mean arterial pressure were recorded. cAMP and cGMP were determined by radioimmunoassay.

RESULTS

Pretreatment with rolipram decreased the duration of ventricular tachycardia without any change in the incidences of dysrhythmias or the mortality rate. This drug did not modify ventricular content of adenosine 3',5'-cyclic monophosphate (cAMP) or guanosine 3',5'-cyclic monophosphate (cGMP). Pimobendan (1 mg kg(-1) + 0.1 mg kg(-1) min) decreased the duration of ventricular tachycardia. This dose of pimobendan and zaprinast (1 mg kg(-1) + 0.1 mg kg(-1) min(-1)) increased the incidence rate of ventricular fibrillation following coronary artery ligation and the mortality rate. Moreover, both drugs increased cGMP in the ventricle.

CONCLUSIONS

The results demonstrated that pimobendan and zaprinast increased the incidence of dysrhythmias and the mortality rate, which was accompanied by an increase in the ventricular content of cGMP. Rolipram decreased the duration of ventricular tachycardia without a change in the cyclic nucleotide content or in the mortality rate.