Summary

Background and objective: The purpose of the present study was to determine the pharmacokinetics of the μ-agonist opioid pirinitramide (piritramide) after prolonged administration.

Methods: Nine patients requiring intensive care therapy and artificial ventilation for several days received piritramide with a median infusion rate of 5 mg h−1 (range 4.8–10 mg h−1) for a median period of 69.9 h (range 49–89 h) for analgesia and sedation. After the end of the infusion, frequent arterial blood samples were withdrawn for 96 h and assayed for piritramide using a gas chromatographic method. Standard compartmental models were fitted to the individual concentration–time courses to characterize the elimination of piritramide after prolonged administration.

Results: The concentration–time course after the end of the infusion was adequately described with a three-compartment model in eight patients and a two-compartment model in one patient (standard two-stage geometric mean and 16–84% quantile: volumes of distribution V1 = 47.9 (26.8–85.8) L, V2 = 402 (241–672) L, V3 = 332 (124–885) L; clearances Cl1 = 66.5 (53.2–83.0)L h−1, Cl2 = 215 (125–369)L h−1, Cl3 = 18.4 (9.2–36.8) L h−1). Both the steady-state volume of distribution (782 L) and the terminal elimination half-life (17.4 h) were larger than predicted from single bolus pharmacokinetic studies (412.5 L and 10.4 h, respectively), the context-sensitive half-time after more than 72 h of administration was 32% shorter than predicted (285 vs. 420 min).

Conclusions: Despite increasing terminal elimination half-life and volume of distribution at steady state (increasing drug load for a given plasma concentration), the context-sensitive half-time of piritramide after3 days of administration is lower than predicted from bolus kinetics, making the drug a suitable candidate for intensive care unit analgesia.

Summary

Background and objective: Combined spinal–epidural (CSE) anaesthesia may be performed using separate needles or by passing the spinal needle through an epidural needle. The latter technique requires that subarachnoid block is performed before the epidural catheter is placed. This paper examines a series of 201 consecutive CSEs performed with a novel separate needle technique, designed to avoid potential and actual problems associated with the CSE technique.

Methods: The CSE technique involved placement of the spinal needle in the subarachnoid space, followed by replacement of the spinal needle stylet. The epidural catheter was then positioned separately before returning to the spinal needle and injecting the subarachnoid drug.

Results: The technique had a high technical success rate. Both needles were successfully placed in 200 (99.5%) cases. Spinal anaesthesia was successful in all cases. The epidural catheter was used in 179 cases and failure of the epidural occurred in 2 (1.1%) cases. Paraesthesia, inability to advance the epidural catheter or blood in the epidural catheter occurred in 31 (15.4%) and necessitated immediate replacement of the epidural catheter in 14 (7%) cases. Postoperatively, typical post-dural puncture headache was reported by one patient (0.5%) and mild backache by four (2%). There were no neurological complications.

Conclusions: This method of CSE anaesthesia can be associated with high success and low complication rates.

Summary

Background and objective: Catheterization of the internal jugular vein is traditionally performed with the patient lying flat or in the Trendelenburg position. This puts patients with elevated intracranial pressure at risk of cerebral herniation. The objective of this study was to assess the safety of real-time ultrasound-guided catheterization of the internal jugular vein in ventilated patients with the patient positioned in a 30° head-up position.

Methods: This prospective, single-centre case series was performed in a 12-bed multi-disciplinary adult intensive care unit (ICU) in a 1500-bed university hospital. The cohort consisted of 64 ventilated ICU patients (14 female, 50 male) with a median age of 52 yr (range 18–85 yr), needing central venous cannulation for insertion of a central venous, haemodialysis or pulmonary artery catheter. The majority of patients presented with risk factors for a difficult cannulation. Catheterization was performed using real-time ultrasound guidance with all patients positioned in 30° dorsal elevation.

Results: Ultrasound-guided cannulation of the internal jugular vein was successful in all patients. There was no evidence of air embolism. Despite a high incidence of anomalous anatomy (39%) no injury to the carotid artery occurred. Central venous access was established in less than 1 min in 75% of patients.

Conclusion: Ultrasound-guided cannulation of the internal jugular vein in ventilated ICU patients can be performed successfully with the patient positioned in 30° dorsal elevation. Potentially deleterious position changes can thus be avoided in high-risk patients.

Summary

Background and objective: Isoflurane has been shown experimentally to protect the myocardium against infarction but the clinical relevance of these findings is not yet well established. We therefore evaluated the effects of isoflurane administration before cardiopulmonary bypass (CPB) on postoperative cardiac troponin I (cTnI) release and clinical outcome in a large group of adult patients scheduled for cardiac surgery.

Methods: Three hundred and fifty-nine consecutive patients were included prospectively in an open observational study and divided into two groups according to whether or not isoflurane was administered before CPB. Postoperative cTnI release, in-hospital mortality, time to discharge from hospital, time to extubation and non-fatal postoperative cardiac events (number of internal cardioversions, need for inotropic support, ischaemic events, dysrhythmias and/or conduction abnormalities) were recorded.

Results: Two hundred and twenty-one (62%) patients did not receive isoflurane and 138 (38%) received isoflurane (1.3% [1.0–1.8%] minimum alveolar concentration over 22 [15–33] min). Postoperative cTnI release was not significantly different between the control and isoflurane groups (5.9 [1.0–336.8] vs. 6.0 [1.5–392.0] ng mL−1, P = 0.88). No significant differences were found in non-fatal cardiac events (63% vs. 57%, P = 0.22) and in-hospital mortality (1.8% vs. 1.4%, P = 0.79) between the control and isoflurane groups.

Conclusions: No significant effect was observed on postoperative cTnI release and in-hospital outcome when isoflurane was added to standardized intravenous anaesthesia before CPB in adult patients undergoing cardiac surgery.

Summary

Background and objective: In previous studies we have demonstrated that it is possible and safe to identify the lumbar epidural space by an acoustic and visible signal. The use of an experimental set-up constructed for this purpose, the acoustic puncture assist device, the lumbar epidural puncture procedure became both audible and visible. In the present study we have extended the use of the device to localize the thoracic epidural space. We have also evaluated whether the device can be used as a practical tool to confirm correct catheter placement.

Methods: In 100 consecutive patients a prototype of the acoustic puncture assist device was connected to the epidural needle in order to localize the epidural space. The device translates the pressure encountered by the needle tip into a corresponding acoustic and visible signal and enables the anaesthesiologist to detect the epidural space by means of the acoustic signal. After catheter insertion, local anaesthetic was administered. Subsequently the epidural block was tested. In 10 patients the device was also connected to the epidural catheter after its insertion into the epidural space.

Results: In all 100 patients included in the study the epidural space was successfully located by means of the acoustic signal. The only recorded complication was intravascular catheter placement in two patients.

Conclusions: It is possible to localize the thoracic epidural space guided by an acoustic signal. The method was shown to be safe, reliable and simple. Potential implications of this technique include better needle control, improved monitoring for training purposes and for clinical documentation of the thoracic epidural puncture as well as identifying correct catheter placement.

Summary

Background and objective: To evaluate the feasibility of an abbreviated focus assessed transthoracic echocardiographic protocol, consisting of four standardized acoustic views for cardiopulmonary screening and monitoring.

Methods: The protocol was applied in 210 patients in a 20-bed multidisciplinary intensive care unit in a university hospital. When inconclusive, an additional transoesophageal echocardiographic examination was performed. Diagnosis, indication, acoustic window, position and value were recorded. Significant pathology, load, dimensions and contractility were assessed.

Results: Two-hundred-and-thirty-three transthoracic and four transoesophageal echoes were performed. The protocol provided usable images of the heart in 97% of the patients, 58% subcostal, 80% apical and 69% parasternal. Images through one window were obtainable in 23%, through two windows in 41% and through three windows in 34%. In 227 patients (97.4%) the focus assessed echo protocol contributed positively. In 24.5% of cases the information was decisive, in 37.3% supplemental and in 35.6% supportive.

Conclusions: By means of an abbreviated, focus assessed transthoracic echo protocol it is feasible to visualize the haemodynamic determinants for assessment and optimization. One or more useful images are obtainable in 97% of critically ill patients.

Summary

Background and objective: Continuous spinal anaesthesia and continuous epidural anaesthesia are both able to provide adequate postoperative pain relief. Combining local anaesthetics and opioids results in synergistic effects. The purpose of this randomized, prospective study was to compare quality of analgesia, side-effects and patient's satisfaction between spinal bupivacaine alone and epidural bupivacaine with sufentanil postoperatively.

Methods: Fifty-nine patients scheduled for hip arthroplasty were randomly assigned either to Group 1 receiving continuous spinal anaesthesia or Group 2 receiving continuous epidural anaesthesia. Postoperatively, those in Group 1 received a 1 mL bolus followed by a continuous infusion of 10 mL/24 h of bupivacaine 0.25%. Those in Group 2 received a 5 mL bolus of lidocaine 2%, followed by a continuous infusion of bupivacaine 0.25% with sufentanil 0.001 mg mL−1 at 4 mL h−1. Pain was measured using a verbal rating score and a visual analogue scale.

Results: Group 1 and Group 2 of 43.3% and 37.9% reported complete analgesia on the verbal rating score. No statistically significant difference was found in the visual analogue scale. Nausea and vomiting occurred significantly more often in Group 2. The patient satisfaction rates did not differ significantly.

Conclusions: Continuous spinal analgesia with bupivacaine alone and continuous epidural analgesia with bupivacaine/sufentanil are both effective for postoperative pain relief after hip replacement. Those patients in the epidural group reported better analgesia but had a higher rate of postoperative nausea and vomiting. Efficacy of pain therapy did not correlate with patient satisfaction.

Summary

Background and objective: We have investigated the toxic and teratogenic effects of certain non-depolarizing muscle relaxants on embryonic development in cultured rat embryos.

Methods: Rat embryos of 9.5 days were explanted and cultured in vitro for 48 h in rat serum. Whole rat serum was used as a culture medium for the control group while different concentrations of atracurium, cis-atracurium, rocuronium and mivacurium were added to rat serum for the experimental groups. Dose-dependent effects of these agents on embryonic developmental parameters were compared using morphological and biochemical methods. Each embryo was evaluated for the presence of any malformations.

Results: When compared to the control embryos, the muscle relaxants significantly decreased all growth and developmental parameters dose dependently with an increase in overall dismorphology. Among these malformations, maxillary deformity was most frequently observed. These effects were observed in much lower doses with atracurium and cis-atracurium compared to those with rocuronium and mivacurium.

Conclusions: Our results suggest that non-depolarizing muscle relaxants cause dose-dependent toxicity on rat embryos at concentrations much greater than those in clinical practice. Although, these agents seems to have a low potential for causing developmental toxicity during organogenesis, because of the lower toxic effects observed with rocuronium and mivacurium, these agents may be preferred when recurrent administrations are necessary for parturients.

Summary

Background and objectives: The American Heart Association guidelines from 2000 recommend that family members be allowed to witness cardiopulmonary resuscitation. This is controversial and opponents fear litigation and family interference during family witnessed resuscitation (FWR). The extent of FWR in UK Emergency Departments is unknown.

Methods: A telephone survey of a selection of UK Emergency Departments was performed asking about experience with FWR.

Results: One-hundred-and-sixty-two UK Emergency Departments with an average attendance of 47 000 patients per year participated. FWR was allowed by 128 (79%) for an adult patient and 93% for a child. Of these, 50% invited relatives to witness and only 21% did not permit FWR. The perceived benefits were: accepting that all possible has been done (48%), accepting the death (48%) and help with grieving (38%). Two percent did not think FWR was of help. Few had encountered any problems or interference from the family. Never being asked was the commonest reason not allowing FWR followed by staff reluctance. Most respondents would wish to be present if their child (85%), spouse/partner (64%) or elderly relative (52%) was being resuscitated.

Conclusions: FWR is common in UK Emergency Departments. It is more common when children are being resuscitated than adults. Further research is needed to demonstrate whether it is of benefit to the patient or relatives and its applicability to other areas such as intensive care.

Summary

Background and objective: For use in a magnetic resonance (MR) scanning room infusion pumps must be MR safe and compatible. This study tested two commonly used infusion pumps (Alaris P6000 and Alaris Asena-GH) to determine if they met these criteria.

Methods: The pumps underwent testing within the scanning room of a 3 T MR scanner. Pump infusion rates were tested at up to 100 Gauss magnetic field strength, with and without radio frequency signals present. The effect of the pumps on image quality was assessed. The occlusion pressure alarm of the pumps was tested at up to 100 Gauss. The projectile risk was assessed by measuring the force exerted upon the pumps at the entrance to the scanner.

Results: The maximum mean flow rate errors at 100 Gauss were 2.18% for the Alaris P6000 and 1.42% for the Alaris Asena-GH, both within our accepted limits. Radio frequency signals had no effect on flow rate. The pumps produced no discernable artefacts on the acquired images. The maximum mean occlusion pressure error was 204 mmHg higher for the Alaris P6000 pump and 99 mmHg lower for the Alaris Asena-GH (P-values < 0.001) at 100 Gauss compared to testing outside the scanner. Both pumps were subject to significant attractive force at the entrance to the scanner.

Conclusions: Whilst the pumps cannot strictly be termed MR safe or compatible at 100 Gauss we have demonstrated that flow rates are unchanged and that, for the Alaris Asena-GH, the effect on the occlusion pressure alarm is unlikely to have patient safety implications.

Summary

Background and aim: Rocuronium may be given to patients for intubation and also after they have received suxamethonium for intubation. The neuromuscular profile of rocuronium given after recovery from suxamethonium may not be identical to that when rocuronium has been given alone. The neuromuscular effects of suxamethonium and rocuronium, and their effects on intraocular pressure (IOP), heart rate (HR) and arterial pressure were also recorded.

Methods: Thirty patients were randomly allocated to receive either 0.6 mg kg−1 rocuronium (n = 15) or 1 mg kg−1 suxamethonium (n = 15) for intubation. Anaesthesia was first induced using propofol 2.5 mg kg−1 and fentanyl 2 μg kg−1 and maintained with propofol 6–12 mg kg−1h−1. The response of the thumb to supramaximal train-of-four (TOF) ulnar nerve stimulation at the wrist was measured using a mechanomyograph. In the suxamethonium group, when the first twitch of the TOF had recovered to 90%, rocuronium 0.6 mg kg−1 was administered. Before administration of relaxant, baseline readings of HR, arterial pressure and IOP were measured until stable, then the appropriate relaxant administered. Thereafter, all readings were repeated at 30, 90, 150, 210 and 270 s. Tracheal intubation was performed 300 s after the intubating dose and all recordings repeated 30 s later. Mechanomyographic monitoring was continued until 70% TOF recovery.

Results: Suxamethonium had a more rapid onset than rocuronium (49 s vs. 74 s, P < 0.0001). The onset time of rocuronium after suxamethonium was significantly reduced (56 s) and the time to recover to a TOF of 70% following rocuronium was increased by previous suxamethonium administration (47 vs. 58 min, P < 0.05). Suxamethonium caused a marked rise in IOP (>30%) and HR (>10%) while rocuronium had little effect on either.

Conclusion: Previous suxamethonium administration decreases the onset time and increases the duration of action of rocuronium. Unlike suxamethonium, rocuronium has few cardiovascular effects and causes little change in IOP.

Summary

Background and objective: The aim of this study was to investigate the quality of intra- and postoperative analgesia obtained by alfentanil compared to that produced by peripheral blockade in children.

Methods: During sevoflurane-nitrous oxide atracurium anaesthesia for minor abdominal or genito-urinary surgery, three groups of children aged 0–8 yr received 25 μg kg−1 alfentanil intravenously (n = 28), or peripheral nerve blockade using 1 mL−1 ropivacaine 0.475% (n = 24), or 12.5 μg kg−1 alfentanil intravenously with peripheral nerve blockade using 1 mL kg−1 ropivacaine 0.475% (n = 30). Changes in blood pressure and heart rate were measured during the procedures. Postoperative pain was assessed using the face, legs, activity, cry, consolability (FLACC) observational tool for quantifying pain behaviour and a numerical scale scored by nurses, doctors, parents and children.

Results: There was no significant difference in intra- or postoperative analgesic efficacy among the three groups. Patients who received alfentanil had significantly lower heart rates than those who received nerve blockade only (96.0 ± 15.6 vs. 115.9 ± 23.2 beats min−1, P < 0.001). FLACC and numerical scale scores did not differ among the groups. There were no significant differences in incidence of vomiting or use of pain medications.

Conclusions: It was concluded that a low-dose, intravenous bolus of alfentanil may be an efficient alternative to peripheral nerve blockade in controlling pain during and after minor abdominal and genito-urinary surgery.