Feedback

The purpose of this section of CEACCP is to provide a forumfor debate and clarification of any controversies arising fromprevious articles David Levy of Nottingham queried the statement regarding i.v.anaesthetic agents in the elderly that ‘Reduced hepaticclearance leads to an increased recovery time even when givenat the correct dose’ (CEACCP 2004; 4: 193–6). DrLevy wrote     

Feedback

The purpose of this section of CEACCP is to provide a forumfor debate and clarification of any controversies arising fromprevious articles This month we received correspondence from Drs Andy Petros,Richard Sarginson, Mark Fox and Rick van Saene of London andLiverpool commenting on the article by Ken Inweregbu, JayshreeDave and Alison Pittard on ‘Nosocomial infections’(CEACCP 2005; 5: 14–17). Dr Petros and colleagues stated     

Feedback

The purpose of this section of CEACCP is to provide a forumfor debate and clarification of any controversies arising fromprevious articles We have received correspondence from David Elcock of Shrewsburyregarding the article on Nitrous Oxide by Amelia Banks and JonathanHardman (CEACCP 2005, 5,5: 145–8), in which it was statedthat filling ratios of nitrous oxide cylinders are less in tropicalcountries. Dr     

Feedback

The purpose of this section of CEACCP is to provide a forumfor debate and clarification of any controversies arising fromprevious articles. We have received correspondence relating to two topics in theOctober 2003 edition of BJA CEPD Reviews. Dr Jeremy Weinbren of London commented on the article on ‘Percutaneoustracheostomy’ by      

Feedback

The purpose of this section of CEACCP is to provide a forumfor debate and clarification of any controversies arising fromprevious articles. We have received correspondence from Bruce Powell of FremantleHospital, Western Australia in connection with the article ‘Currentcontroversies in neuroanaesthesia, head injury management andneuro critical care’ by Drs Mishra, Rajkumar and Hancock(CEACCP 2006; 6,2:79–82). Dr Powell questions the suggestionthat ‘blood glucose should be strictly maintained at     

Feedback

The purpose of this section of CEACCP is to provide a forumfor debate and clarification of any controversies arising fromprevious articles Dr Jim     

Feedback

We received correspondence from Nick Lavies of Worthing in connectionwith the article by Radha Ravi and Tanya Howell on ‘Anaesthesiafor paediatric ear nose and throat surgery’ (CEACCP 2007;7(2): 33–37). Dr Lavies commented on the issues of airwaymanagement, management of the bleeding tonsil, and anaesthesiafor oesophagoscopy. He questioned the statement that ‘only16% of anaesthetists used the reinforced laryngeal mask airwayroutinely. However, no mention is made of the CJD problem whichforced me and I suspect a good     

On-line continuing education--another step forward

From the start of 2007, both the British Journal of Anaesthesiaand our continuing medical education (CME) journal ContinuingEducation in Anaesthesia, Critical Care and Pain (CEACCP) willbe making multiple choice questions (MCQs) for CME availableon-line through the journals' websites. The BJA has a commitmentto providing continuing medical education and we have been atthe forefront of the     

Web-based continuing education

Continuing Education in Anaesthesia, Critical Care and Pain(CEACCP) Volume 1, Number 1 was published in February 2001;its mission is to provide an easily accessible, up-to-date sourceof continuing medical education for anaesthetists. It is thesister     

Desflurane compared with propofol for postoperative sedation in the intensive care unit

Background. We hypothesized that emergence from sedation inpostoperative patients in the intensive care unit would be fasterand more predictable after sedation with desflurane than withpropofol. Methods. Sixty patients after major operations were allocatedrandomly to receive either desflurane or propofol. The targetlevel of sedation was defined by a bispectral index^TM (BIS^TM)of 60. All patients were receiving mechanical ventilation ofthe lungs for 10.6 (SD 5.5) h depending on their clinical state.The study drugs were stopped abruptly in a calm atmosphere withthe fresh gas flow set to 6 litres min^–1, and the timeuntil the BIS increased above 75 was measured (t_BIS75, the mainobjective measure). After extubation of the trachea, when thepatients could state their birth date, they were asked to memorizefive words. Results. Emergence times were shorter (P<0.001) after desfluranethan after propofol (25th, 50th and 75th percentiles): t_BIS75,3.0, 4.5 and 5.8 vs 5.2, 7.7 and 10.3 min; time to first response,3.7, 5.0 and 5.7 vs 6.9, 8.6 and 10.7 min; time to eyes open,4.7, 5.7 and 8.0 vs 7.3, 10.5 and 20.8 min; time to squeezehand, 5.1, 6.5 and 10.2 vs 9.2, 11.1 and 21.1 min; time to trachealextubation, 5.8, 7.7 and 10.0 vs 9.7, 13.5 and 18.9 min; timeto saying their birth date, 7.7, 10.5 and 15.5 vs 13.0, 19.4and 31.8 min. Patients who received desflurane recalled significantlymore of the five words. We did not observe major side-effectsand there were no haemodynamic or laboratory changes exceptfor a more marked increase in systolic blood pressure afterstopping desflurane. Using a low fresh gas flow (air/oxygen1 litre min^–1), pure drug costs were lower for desfluranethan for propofol (95 vs 171 Euros day^–1). Conclusions. We found shorter and more predictable emergencetimes and quicker mental recovery after short-term postoperativesedation with desflurane compared with propofol. Desfluraneallows precise timing of extubation, shortening the time duringwhich the patient needs very close attention. Br J Anaesth 2003; 90: 273–80     

Erratum

Severe meningococcal disease in childhood (BJA 2003;      

Assessment of preoperative fluid depletion using bioimpedance analysis

Background. Fluid depletion during the perioperative periodis associated with poorer outcome. Non-invasive measurementof total body water by bioimpedance may enable preoperativefluid depletion and its influence on perioperative outcome tobe assessed. Methods. Weight and foot bioimpedance were recorded under standardizedconditions in patients undergoing bowel preparation (n=43) orday surgery (n=44). Fifteen volunteers also followed standardnil-by-mouth instructions on two separate occasions to assessthe variabilities of weight and bioimpedance over time. Results. Body weight fell by 1.27 kg (95% CI 1.03–1.50kg; P<0.0001) and foot bioimpedance increased by 51 ohm afterbowel preparation (95% CI 36–66; P<0.0001). Weightchange after the nil-by-mouth period in day-surgery patients(mean –0.22 kg, 95% CI –0.05 to –0.47 kg;P=0.07) correlated (r=–0.46; P=0.005) with an increasein bioimpedance (16 ohms, 95% CI 5–27 ohms; P=0.01). Nodifference between two separate bioimpedance measurements wasseen in the volunteer group. Conclusions. Further work is warranted to determine if bioimpedancechanges may serve as a useful indicator of perioperative fluiddepletion. Br J Anaesth 2004; 92: 134–6     

NICE guidelines for central venous catheterization in children. Is the evidence base sufficient?

Background. Recent guidelines from the National Institute forClinical Excellence (NICE) recommend the use of ultrasound guidancefor central venous catheterization in children. This study prospectivelyexamined the use of ultrasound guidance for central venous catheterizationin children undergoing heart surgery. Methods. One hundred and twenty-four infants and children wererandomized to either ultrasound-guided or traditional landmark-guidedcentral venous catheterization. Results. Success rates were significantly greater in the landmarkgroup compared with the ultrasound group (89.3% vs 78%, P<0.002),and arterial puncture rates were significantly lower in thelandmark group (6.2% vs 11.9%, P<0.03). There was no significantdifference between the two groups in the time taken to performthe catheterization. Conclusions. These results are different from the publishedresults on which the NICE guidelines were based; however, theevidence base in children is small. There is currently insufficientevidence to support the use of ultrasound guidance for centralvenous catheterization in children. Br J Anaesth 2004; 92: 827–30     

Posture used by anaesthetists during laryngoscopy

Background. There is little advice on the posture to be usedwhen intubating the trachea. Does the stance used depend onexperience? Methods. Twenty-six subjects with varying experience of intubationwere photographed during laryngoscopy of an intubation trainingmannequin. Posture was measured from the photographs and thedata were analysed with the Mann–Whitney U-test. Results. The less experienced group had shallower lines of sight,levered more, and stood with their face closer to the mannequin(P=0.037, 0.018 and 0.06 respectively). Conclusions. Novice anaesthetists should be given explicit instructionson correct trolley height and should be taught to intubate witha straight back. Br J Anaesth 2002; 89: 772–4     

Differential effects of intravenous anaesthetic agents on the response of rat mesenteric microcirculation in vivo after haemorrhage

Background. The differential effects of i.v. anaesthesia onthe response of the mesenteric microcirculation after haemorrhagein vivo are previously unexplored. Methods. Male Wistar rats (n=56) were anaesthetized intravenouslyeither with propofol and fentanyl (propofol/fentanyl), ketamineor thiopental. A tracheostomy and carotid cannulation were performedand the mesentery surgically prepared for observation of themicrocirculation using fluorescent in vivo microscopy. Animalswere allocated to one of three groups: control, haemorrhageor haemorrhage re-infusion. Results. After haemorrhage, the response of the microcirculationdiffered during propofol/fentanyl, ketamine and thiopental anaesthesia.During propofol/fentanyl anaesthesia there was constrictionof arterioles (–16.7 (3.9)%), venules (–5.9 (1.7))and capillaries (–16.3 (2.8)) (n=12). During ketamineand thiopental anaesthesia both constriction and dilation wasobserved. After haemorrhage and re-infusion, macromolecularleak occurred from venules during propofol/fentanyl and thiopentalanaesthesia (P<0.05), but not during ketamine anaesthesia. Conclusion. In summary, i.v. anaesthetic agents differentiallyalter the response of the mesenteric microcirculation to haemorrhage. Br J Anaesth 2002; 88: 255–63     

Effect of intrathecal tramadol administration on postoperative pain after transurethral resection of prostate

Background. Tramadol administered epidurally has been demonstratedto decrease postoperative analgesic requirements. However, itseffect on postoperative analgesia after intrathecal administrationhas not yet been studied. In this double-blind, placebo-controlledstudy, the effect of intrathecal tramadol administration onpain control after transurethral resection of the prostate (TURP)was studied. Methods. Sixty-four patients undergoing TURP were randomizedto receive bupivacaine 0.5% 3 ml intrathecally premixed witheither tramadol 25 mg or saline 0.5 ml. After operation, morphine5 mg i.m. every 3 h was administered as needed for analgesia.Postoperative morphine requirements, visual analogue scale forpain at rest (VAS) and sedation scores, times to first analgesicand hospital lengths of stay were recorded by a blinded observer. Results. There were no differences between the groups with regardto postoperative morphine requirements (mean (SD): 10.6 (7.9)vs 9.1 (5.5) mg, P=0.38), VAS (1.6 (1.2) vs 1.2 (0.8), P=0.18)and sedation scores (1.2 (0.3) vs 1.2 (0.2), P=0.89). Timesto first analgesic (6.3 (6.3) vs 7.6 (6.2) h, P=0.42) and lengthof hospital stay (4.7 (2.8) vs 4.4 (2.2) days, P=0.66) weresimilar in the two groups. Conclusion. Intrathecal tramadol was not different from salinein its effect on postoperative morphine requirements after TURP. Br J Anaesth 2003; 91: 536–40     

Constipation and its implications in the critically ill patient

Background. Motility of the lower gut has been little studiedin intensive care patients. Method. We prospectively studied constipation in an intensivecare unit of a university hospital, and conducted a nationalsurvey to assess the generalizability of our findings. Results. Constipation occurred in 83% of the patients. Moreconstipated patients (42.5%) failed to wean from mechanicalventilation than non-constipated patients (0%), P<0.05. Themedian length of stay in intensive care and the proportion ofpatients who failed to feed enterally were greater in constipatedthan non-constipated patients (10 vs 6.5 days and 27.5 vs 12.5%,respectively (NS)). The survey found similar observations inother units. Delays in weaning from mechanical ventilation andenteral feeding were reported by 28 and 48% of the units surveyed,respectively. Conclusions. Constipation has implications for the criticallyill. Br J Anaesth 2003; 91: 815–19     

Comparison of the effects of intrathecal ropivacaine, levobupivacaine, and bupivacaine for Caesarean section

Background. This study aimed to detect if intrathecal (i.t.)ropivacaine and levobupivacaine provided anaesthesia (satisfactoryanalgesia and muscular relaxation) and postoperative analgesiaof similar quality to bupivacaine in patients undergoing Caesareansection. Methods. Ninety parturients were enrolled. A combined spinal-epiduraltechnique was used. Patients were randomly assigned to receiveone of the following isobaric i.t. solutions: bupivacaine 8mg (n=30), levobupivacaine 8 mg (n=30), or ropivacaine 12 mg(n=30), all combined with sufentanil 2.5 µg. An i.t. solutionwas considered effective if an upper sensory level to pinprickof T4 or above was achieved and if intraoperative epidural supplementationwas not required. Sensory changes and motor changes were recorded. Results. Anaesthesia was effective in 97, 80, and 87% of patientsin the bupivacaine 8 mg, levobupivacaine 8 mg, and ropivacaine12 mg groups, respectively. Bupivacaine 8 mg was associatedwith a significantly superior success rate to that observedin the levobupivacaine group (P<0.05). It also provided alonger duration of analgesia and motor block (P<0.05 vs levobupivacaineand ropivacaine). Conclusions. The racemic mixture of bupivacaine combined withsufentanil remains an appropriate choice when performing Caesareansections under spinal anaesthesia. Br J Anaesth 2003; 91: 684–9     

Can molecular similarity-activity models for intravenous general anaesthetics help explain their mechanism of action?

Background. The importance of molecular shape and electrostaticpotential in determining the activities of 11 structurally-diversei.v. general anaesthetics was investigated using computationalchemistry techniques. Methods. The free plasma anaesthetic concentrations that abolishedthe response to noxious stimulation were obtained from the literature.The similarities in the molecular shapes and electrostatic potentialsof the agents to eltanolone (the most potent anaesthetic agentin the group) were calculated using Carbo indices, and correlatedwith in vivo potency. Results. The best model obtained was based on the similaritiesof the anaesthetics to two eltanolone conformers (r²=0.820).This model correctly predicted the potencies of the R- and S-enantiomersof ketamine, but identified alphaxalone as an outlier. Exclusionof alphaxalone substantially improved the activity correlation(r²=0.972). A bench mark model based on octanol/water partitioncoefficients (r²=0.647) failed to predict the potency orderof the ketamine enantiomers. Conclusions. The results demonstrate that a single activitymodel can be formulated for chiral and non-chiral i.v. anaestheticagents using molecular similarity indices. Br J Anaesth 2002; 88: 166–74     

Exhaled nitric oxide as a marker of lung injury in coronary artery bypass surgery

Background. Exhaled nitric oxide (NO) concentrations have beensuggested as a marker of disease onset and severity in a numberof inflammatory conditions such as acute asthma. Known markersof the onset of acute lung injury require invasive tests andlaboratory based analysis and have limited clinical applicability.We performed a study of the use of exhaled NO as a marker ofdeveloping acute lung injury during and after coronary arterybypass grafting in patients requiring cardiopulmonary bypass. Methods. Mixed expired air samples were taken from the patientbreathing system and analysed for exhaled NO using chemiluminescenceanalysis. Results. Exhaled nitric oxide concentrations in expired gascorrelated with the Pa_O2/FI_O2 ratio (r=0.23, P<0.01). Therewas a non-significant trend towards a reduction in exhaled NOlevels from after induction of anaesthesia to post-bypass timepoints, with the lowest exhaled NO concentrations occurringat this time (P=0.07). There was no correlation between meanarterial pressure (r=–0.1, P=0.54) or mean pulmonary arterypressure (r=–0.1, P=0.67) and expired NO levels. Conclusions. Further work is required to test whether exhaledNO concentration may be useful in diagnosing the onset of acutelung injury in patients undergoing coronary artery bypass grafting. Br J Anaesth 2002; 89: 247–50