BRADYCARDIA AND VECURONIUM: COMPARISON WITH ALCURONIUM DURING CHOLECYSTECTOMY

We have compared the incidence of bradycardia in two groupsof patients undergoing cholecystectomy. Twenty consecutive patientswere allocated randomly to receive either vecuronium (n=8) oralcuroniume (n=12) as part of a standard anaesthetic technique.Bradycardia was defined as a heart rate less then 50 beat min^–1.Five episodes of bradycardia occurred with vecuronium and nonewith alcuronium (P<0.01).     

The new age of medical genomics

"I would have everie man write what he knowes and no more."—Montaigne Genomic tools have enhanced research across all of medicine,including anaesthesia. Our understanding of both acute responsesof the heart (such as myocardial preconditioning, ischaemia–reperfusion,stunning and infarction), as well as the onset and developmentof chronic heart disease, is undergoing a paradigm shift asfunctional genomic and proteomic research is providing furtherinsights into the complex dynamic regulation of myocardial geneinteractions and pathways. In this issue of the British Journalof Anaesthesia, Lucchinetti and colleagues¹ demonstrate theuse of genome-based technologies to discover mechanisms underlyingimportant clinical questions such as how best to protect theheart in settings of ischaemia. One protective strategy is ischaemicpreconditioning, defined as a brief period of controlled ischaemiafollowed by reperfusion prior to a longer period of     

HALOTHANE DOES NOT DEPRESS CONTRACTILE FUNCTION OF FRESH OR FATIGUED DIAPHRAGM IN PENTOBARBITONE-ANAESTHETIZED DOGS

We have studied the effect of halothane on diaphragmatic contractilefunction by measuring transdiaphragmatic pressure (Pdi) andelectromyogram of the diaphragm (Edi) during various stimulationfrequencies in 15 pentobarbitone anaesthetized dogs undergoingmechanical ventilation. We have examined also the effect ofhalothane on the fatigued diaphragm by repeating the measurements5, 10, 15, 30, 60 and 90 min after 30 min of tetanic stimulationapplied to the phrenic nerves. Administration of 1–2 MACof halothane did not affect Pdi at any given stimulation frequency.Changes in the depth of halothane anaesthesia (0, 1 and 2 MAC)did not alter the force-frequency relationship of the diaphragmduring recovery from fatigue. Edi was unaffected by halothane,except for a small decline during 100-Hz stimulation with 2MAC. In contrast with the changes in Pdi, Edi during recoveryfrom fatigue was the same as that determined before fatigue.It is concluded that halothane, in clinical concentrations,did not depress the contractile function of fresh or fatigueddiaphragm in vivo.     

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     

EFFECT OF SODIUM NITROPRUSSIDE-INDUCED HYPOTENSION ON PULMONARY DEADSPACE

Deliberate hypotension with nitroprusside produced a 40% reductionin mean arterial pressure, but it did not cause any change inthe pulmonary deadspace to tidal volume ratio (VD/VT). Thiswas achieved by adequate hydration both before and during hypotension,as indicated by constant filling pressures. Thus we have shownthat deliberate hypotension per se does not increase VD/VT,and that vasodilataaon may bring about a relatively hypovolaemicstate and be responsible for the increase in VD/VT observedby previous workers     

SPECIFIC ADRENERGIC BETA-RECEPTOR BLOCKADE IN THE PREVENTION OF ADRENALINE-INDUCED VENTRICULAR ARRHYTHMIAS IN DOGS ANAESTHETIZED WITH HALOTHANE IN NITROUS OXIDE-OXYGEN

A new beta-receptor blocking agent N-isopropyl-p-nitrophenylethanolaminehydro-chloride (dl-INPEA) and its levo-rotatory (l-INPEA) anddextro-rotatory (d-INPEA) isomers have been used as tools toanalyze the specificity of adrenergic beta-receptor blockadein the prevention of arrhythmias induced by adrenaline duringhalothane-nitrous oxide anaesthesia in vagotomized dogs. l-INPEA,a pure beta-receptor blocking drug with no local anaestheticaction, was most potent, while d-INPEA, a drug with negligiblebeta-receptor blocking activity, was least potent in preventingthese arrhythmias. dl-INPEA, a drug having both beta-receptorblocking and some local anaesthetic activity, showed moderateanti-arrhythmic activity. The anti-arrhythmic activity has beencorrelated with specific beta-receptor blockade produced bythese drugs. It is concluded that the prevention of adrenaline-evokedarrhythmias is due to specific blockade of beta-receptors.     

Vibrio vulnificus peritonitis after eating raw sea fish in a patient undergoing continuous ambulatory peritoneal dialysis (CAPD)

Sir, Vibrio vulnificus is an opportunistic pathogen that can causeserious, life-threatening infection in susceptible persons.Patients with chronic liver disease, alcoholism, immunodeficiencies,haemochromatosis or other iron overload states have increasedsusceptibility to infection by Vibrio species [1]. End-stagerenal disease (ESRD) has been identified as a     

Comparison of the effects of sevoflurane, isoflurane and halothane on indocyanine green clearance

We have examined the effects of inhalation anaesthetics on indocyaninegreen (ICG) clearance, as an index of hepatic function, in patientsundergoing elective surgery. Recently, a new method has beendeveloped to measure in real-time the disappearance rate ofICG from plasma. This method eliminates the multiple samplingand delay of the conventional ICG test. ICG clearance is displayedas two indices: K (ICG disappearance rate) and R₁₅ (ICG retentionrate 15 min after injection of ICG 0.5 mg kg^–1 This measurementwas performed in patients before and after 1 MAC of sevoflurane(n = 6), 2 MAC of sevoflurane (n = 6), 1 MAC of isoflurane (n= 6), 2 MAC of isoflurane (n = 6), 1 MAC of halothane (n = 6)or 2 MAC of halothane (n = 6) without surgical stress. Althoughmean arterial pressure decreased significantly at 1 and 2 MACof sevoflurane, 2 MAC of halothane, and 1 and 2 MAC of isoflurane,ICG clearance was maintained at awake levels, except at 2 MACof halothane (K mean - 33 (SEM 3)%, R = + 90 (3)% from awakevalues). We conclude that sevoflurane and isoflurane have amore favourable effect on liver circulation than halothane.      

Influence of working conditions on job satisfaction in anaesthetists

Background. We studied job satisfaction, physical health, emotionalwell-being and working conditions in 125 Austrian and Swissanaesthetists. Methods. Responses to self-reporting questionnaires were evaluated.Dependent variables included job satisfaction, emotional well-beingand physical health. Independent variables included age, sex,marital status, position and working conditions as assessedby the Instrument for Stress-related Job Analysis. Results. Control over work shows a strong effect on job satisfactionin anaesthetists, for example influence on handling tasks (P=0.001),time control (P=0.002) and participation (P=0.001), whereastask demands and task-related problems did not have any effect.Anaesthetists in leading positions and specialists reportedlower job satisfaction (P=0.012) than did anaesthetists in non-leadingpositions. Job satisfaction was associated with better physicalhealth (P=0.001) and better emotional well-being (P=0.005). Conclusions. Our results suggest that a high level of job satisfactionin anaesthetists correlates with interesting work demands andthe opportunity to contribute skills and ideas. To improve jobsatisfaction, more attention should be paid to improving workingconditions, including control over decision-making, and allowinganaesthetists to have more influence on their own work paceand work schedule.     

Effects of sevoflurane on hypoxic pulmonary vasoconstriction in anaesthetized piglets

In vitro, halogenated agents reduce the pulmonary vasoconstrictorresponse to alveolar hypoxia in isolated perfused lungs. However,studies in intact animals have been less convincing. The aimof the present study was to assess the effect of sevofluraneon hypoxic pulmonary vasoconstriction (HPV) in anaesthetizedpiglets using the pressure/cardiac index relationship (P/Q).Tenlarge white piglets were anaesthetized and mechanically ventilated,alternately in hyperoxia (FI_O2=0.4) and hypoxia (FI_O2=0.12).Multipoint plots of pulmonary arterial pressure (PAP) or differencesbetween PAP and left atrial pressure (LAP) against Q were generatedby gradual inflation of a balloon introduced into the inferiorvena cava. P/Q relationships were established in hyperoxia andhypoxia at baseline, and then with sevoflurane. In hypoxia,pressure gradients (PAP – LAP) increased at every levelof Q, thus demonstrating active pulmonary vasoconstriction.Sevoflurane at 1 MAC did not affect these P/Q relationshipsin hyperoxia or hypoxia as compared with baseline. Sevofluraneat a clinically relevant concentration (1 MAC) has no significanteffect on HPV in anaesthetized piglets. Br J Anaesth 2000; 85: 440–5     

Differences in burnout between Northern and Southern Italian dialysis health-care providers.

Sir, I have read with interest the excellent paper by Klersy et al.,examining burnout in dialysis health care providers [1]. Althoughseveral studies have shown that 25–30% of health-careprofessionals develop burnout symptoms as a consequence of theirclinical activities, little data are currently available onburnout rates in dialysis health-care workers. Klersy et al. [1] compared burnout levels in 344 nurses andphysicians working in dialysis units in Northern Italy, andinvestigated     

Duration of spinal anaesthesia is determined by the partition coefficient of local anaesthetic

We have compared the duration of motor block produced by fourlocal anaesthetics administered into a chronically implantedsubarachnoid catheter in rabbits. Each group (n = 6) receivedfour different doses of amethocaine, bupivacaine, lignocaineor procaine, and the duration of the resulting motor block wasassessed. Dose-response curves were plotted for each drug. Asa measure of activity of the anaesthetics, we used the doseof each drug required to produce block of 60-min duration (D_60min)and the correlation between D_60min and different drug propertieswas examined. An inverse linear correlation (r = 0.995; P <0.01) was observed between log D_60min and the log of the partitioncoefficient of the local anaesthetics. No correlation was foundbetween the effect and degree of protein binding, pKa or molecularweight. These results suggest that, in spinal anaesthesia, thepartition coefficient could be used as a predictor of the durationof anaesthetic action. (Br. J. Anaesth. 1994; 72: 456–459)     

EFFECTS OF ENFLURANE ON CARDIOVASCULAR FUNCTION

Throughout the text of this paper, and in figure 3, the indexof myocardial contractility, dp/dt IIP, should have been expressedas a ratio, dp/dt: IIP.     

Effect of magnesium on coagulation as measured by thrombelastography

Magnesium has long been assumed to have anticoagulant properties,but the effect has been poorly quantified. The thrombelastograph(TEG) was used to evaluate the effect of magnesium using bloodfrom volunteers. Magnesium sulphate was added to one blood sampleand another sample was used as a control. Both samples weretested simultaneously and the results evaluated against themagnesium concentration measured in each sample. At serum magnesiumconcentrations < 3 mmol litre^–1, there were no significanteffects of magnesium. With increasing magnesium concentrationsthere was a statistically significant but small prolongationof the r time, k time and r+k time. Maximum amplitude was affectedonly at magnesium concentrations > 7 mmol litre^–1 Magnesiumhas only minimal effects on coagulation which are unlikely tobe clinically important.     

DEPRESSION OF RESPIRATORY DRIVE BY DIAZEPAM AS PREMEDICATION

The respiratory effects of premedication with i.v. injectionof diazepam have been assessed in 10 healthy patients awaitingminor operative procedures. Measurements were recorded beforeand 60min after administration of diazepam 0.14mg kg^–1.Mouth occlusion pressure (P_0.1) was used as an index of neuromuscularinspiratory drive. Minute-ventilation (V_E), respratory frequency(f) and mean inspiratory flow rate (V_T/T_I) were significantlyreduced after diazepam. During carbon dioxide rebreathing theslopes of V_E, f, V_T/T_I and P_0.1 with PA_CO, were significantlyreduced. These results confirm that i.v. diazepam produces significantrespiratory depression in healthy subjects. We conclude thatdiazepam used under clinical conditions depresses the respiratorycentre.     

The Montgomery T-tube: anaesthetic problems and solutions

The Montgomery T-tube is a device used as a combined trachealstent and an airway after laryngotracheal surgery. The deviceis used mostly in specialist centres for head and neck surgery,and therefore, many anaesthetists may be unfamiliar with itsuse. The Montgomery T-tube presents the anaesthetist with challengesboth during its surgical insertion when acute loss of the airwaymight occur and also during induction of anaesthesia in patientswho have such a tube in situ. Anaesthetists who are unfamiliarwith the tube may have to resort to ingenious ways of copingwith the problems of a shared airway with a T-tube, which doesnot have a suitable adaptor for a standard catheter mount, aswell as controlling and maintaining ventilation through thedevice. Safe management of such patients requires careful planning.We describe the anaesthetic management of two cases to illustratethe problems associated with Montgomery tubes. Br J Anaesth 2001; 87: 787–90     

Preoxygenation in healthy volunteers: a graph of oxygen "washin" using end-tidal oxygraphy

End-tidal oxygen fractions (FE'_o2) have been measured in 40healthy volunteers breathing 100% oxygen. On the assumptionthat FE'_o2 is a good measure of alveolar oxygen, we have drawna graph of oxygen washin vs time. Clinical applications arediscussed. (Br. J. Anaesth. 1994; 72: 116–118)     

Myofibroblasts, predictors of progression of mesangial IgA nephropathy?

The limited knowledge of the cellular mediators of renal scarringhampers progress in the management of progressive chronic renalfailure (CRF). We have studied 38 patients with biopsy-provenmesangial IgA nephropathy with emphasis on attempting to definethe role of myofibroblasts(-smooth muscle actin/SMA-positivecells) in renal scarring. In 18 untreated patients, correlationswere undertaken between known histological parameters of progressionas well as the presence of myofibroblasts in tissues and theclinical outcome. -SMA staining by an avidin-biotin-peroxidasemethod was confined to a large extent to the vascular smoothmuscle cells of normal kidneys but extended to the tubulointerstitiumand periglomerular space in scarred kidneys. Mild glomerularstaining was also noted. The interstitial immunostain followeda similar distribution to that of interstitial type III collagen.Morphometric analysis showed the interstitial SMA staining tobe a reliable histological predictor of outcome as it discriminatedbetween progressors and non-progressors (²=4.923, P=0.026).The intensity of the interstitial -SMA staining correlated withrenal functional outcome; inversely with the reciprocal of serumcreatinine slopes (r=-0.466, P<0.025) and positively withthe serum creatinine value at the end of the observation period(r=0.704, P<0.00l). Other histological parameters that correlatedwith outcome included the degree of tubulointerstitial (TI)inflammatory infiltrate (r=-0.425, P<0.05 with 1/Cr slopeand r=0.760, P< with serum creatinine) and the intensityof the TI staining for collagen IV (r=-0.567 and 0.667 respectively).In 20 patients treated with prednisolone and azathioprine, asecond renal biopsy showed the persistence of interstitial myofibroblastsin the absence of progressive fibrosis. In conclusion, stainingof renal biopsies of patients with mesangial IgA for -SMA-positivecells may identify the myofibroblasts as important mediatorsof TI scarring and have useful prognostic implications.     

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     

Haemodynamic and renal effects of intravenous enalaprilat during coronary artery bypass graft surgery in patients with ischaemic heart dysfunction

Renal dysfunction occurring after open heart surgery is multifactorialin origin but activation of the renin–angiotensin systemmay have a prominent role. Fourteen patients with ischaemicheart dysfunction scheduled for elective coronary artery bypassgraft (CABG) surgery were allocated to a treatment group [enalaprilatfor 2 days; ACEI (angiotensin-converting enzyme inhibitor) group,n=7] or a control group (n=7). The cardiac index was significantlyhigher in ACEI-treated patients than in the controls beforeand after cardiopulmonary bypass (CPB) (P<0.05) and on postoperativeday 2 (P<0.05). The systemic vascular resistance wassignificantly lower in the ACEI-treated patients than in thecontrols before and after CPB (P<0.05). Renal plasma flow,measured as [¹³¹I]orthoiodohippuran clearance (Cl_H), was higherin the ACEI group than in the control group before CPB, as wasendogenous creatinine clearance after CPB (P<0.05). On post-operativeday 7, Cl_H was significantly higher in the ACEI group thanin the control group (P<0.05). Plasma renin activity andvasopressin concentration increased in both groups during CPB(P<0.05). The study demonstrates that administration of ani.v. ACEI, enalaprilat, improves cardiac output during CABGsurgery in patients with ischaemic heart dysfunction. Moreover,renal perfusion was better maintained during surgery, and thiseffect was sustained up to post-operative day 7. Br J Anaesth 2001; 86: 169–75