Towards high-quality peri-operative care: a global perspective

Article 25 of the United Nations' Universal Declaration of Human Rights enshrines the right to health and well-being for every individual. However, universal access to high-quality healthcare remains the purview of a handful of wealthy nations. This is no more apparent than in peri-operative care, where an estimated five billion individuals lack access to safe, affordable and timely surgical care. Delivery of surgery and anaesthesia in low-resource environments presents unique challenges that, when unaddressed, result in limited access to low-quality care. Current peri-operative research and clinical guidance often fail to acknowledge these system-level deficits and therefore have limited applicability in low-resource settings. In this manuscript, the authors priority-set the need for equitable access to high-quality peri-operative care and analyse the system-level contributors to excess peri-operative mortality rates, a key marker of quality of care. To provide examples of how research and investment may close the equity gap, a modified Delphi method was adopted to curate and appraise interventions which may, with subsequent research and evaluation, begin to address the barriers to high-quality peri-operative care in low- and middle-income countries.

Improving care at scale: process evaluation of a multi-component quality improvement intervention to reduce mortality after emergency abdominal surgery (EPOCH trial)

BACKGROUND

Improving the quality and safety of perioperative care is a global priority. The Enhanced Peri-Operative Care for High-risk patients (EPOCH) trial was a stepped-wedge cluster randomised trial of a quality improvement (QI) programme to improve 90-day survival for patients undergoing emergency abdominal surgery in 93 hospitals in the UK National Health Service.

METHODS

The aim of this process evaluation is to describe how the EPOCH intervention was planned, delivered and received, at both cluster and local hospital levels. The QI programme comprised of two interventions: a care pathway and a QI intervention to aid pathway implementation, focussed on stakeholder engagement, QI teamwork, data analysis and feedback and applying the model for improvement. Face-to-face training and online resources were provided to support senior clinicians in each hospital (QI leads) to lead improvement. For this evaluation, we collated programme activity data, administered an exit questionnaire to QI leads and collected ethnographic data in six hospitals. Qualitative data were analysed with thematic or comparative analysis; quantitative data were analysed using descriptive statistics.

RESULTS

The EPOCH trial did not demonstrate any improvement in survival or length of hospital stay. Whilst the QI programme was delivered as planned at the cluster level, self-assessed intervention fidelity at the hospital level was variable. Seventy-seven of 93 hospitals responded to the exit questionnaire (60 from a single QI lead response on behalf of the team); 33 respondents described following the QI intervention closely (35%) and there were only 11 of 37 care pathway processes that > 50% of respondents reported attempting to improve. Analysis of qualitative data suggests QI leads were often attempting to deliver the intervention in challenging contexts: the social aspects of change such as engaging colleagues were identified as important but often difficult and clinicians frequently attempted to lead change with limited time or organisational resources.

CONCLUSIONS

Significant organisational challenges faced by QI leads shaped their choice of pathway components to focus on and implementation approaches taken. Adaptation causing loss of intervention fidelity was therefore due to rational choices made by those implementing change within constrained contexts. Future large-scale QI programmes will need to focus on dedicating local time and resources to improvement as well as on training to develop QI capabilities.

EPOCH TRIAL REGISTRATION

ISRCTN80682973 https://doi.org/10.1186/ISRCTN80682973 Registered 27 February 2014 and Lancet protocol 13PRT/7655.

Estimated costs before, during and after the introduction of the emergency laparotomy pathway quality improvement care (ELPQuIC) bundle

Implementation of a quality improvement bundle for peri-operative management of emergency laparotomy (ELPQuIC) improved mortality in a previous study. We used data from one site that participated in that study to examine whether it was associated with the cost of care. We collected data from 396 patients: 144 before, 144 during and 108 after implementation of the bundle. We estimated costs incurred using previously published methodology based on the time the patient spent in hospital, in the operating theatre and in critical care. Duration of stay in hospital and critical care did not differ between time periods, p = 0.14 and p = 0.28, respectively. The costs per patient and per survivor did not differ between the time periods, p = 0.87 and p = 0.17, respectively. Costs were similar for patients aged < 80 years vs. ≥ 80 years. Implementation of a quality improvement bundle for emergency laparotomy has the capacity to save lives without increasing hospital costs.

Use of a pathway quality improvement care bundle to reduce mortality after emergency laparotomy

Background

Emergency laparotomies in the UK, USA and Denmark are known to have a high risk of death, with accompanying evidence of suboptimal care. The emergency laparotomy pathway quality improvement care (ELPQuiC) bundle is an evidence-based care bundle for patients undergoing emergency laparotomy, consisting of: initial assessment with early warning scores, early antibiotics, interval between decision and operation less than 6 h, goal-directed fluid therapy and postoperative intensive care.

Methods

The ELPQuiC bundle was implemented in four hospitals, using locally identified strategies to assess the impact on risk-adjusted mortality. Comparison of case mix-adjusted 30-day mortality rates before and after care-bundle implementation was made using risk-adjusted cumulative sum (CUSUM) plots and a logistic regression model.

Results

Risk-adjusted CUSUM plots showed an increase in the numbers of lives saved per 100 patients treated in all hospitals, from 6·47 in the baseline interval (299 patients included) to 12·44 after implementation (427 patients included) (P < 0·001). The overall case mix-adjusted risk of death decreased from 15·6 to 9·6 per cent (risk ratio 0·614, 95 per cent c.i. 0·451 to 0·836; P = 0·002). There was an increase in the uptake of the ELPQuiC processes but no significant difference in the patient case-mix profile as determined by the mean Portsmouth Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity risk (0·197 and 0·223 before and after implementation respectively; P = 0·395).

Conclusion

Use of the ELPQuiC bundle was associated with a significant reduction in the risk of death following emergency laparotomy.

Current UK practice in emergency laparotomy

INTRODUCTION

Emergency laparotomy is a common procedure, with 30,000-50,000 performed annually in the UK. This large scale study reports the current spectrum of emergency laparotomies, and the influence of the surgical procedure, underlying pathology and subspecialty of the operating surgeon on mortality.

METHODS

Anonymised data on consecutive patients undergoing an emergency laparotomy were submitted for a three-month period. The primary outcome measure was unadjusted 30-day mortality. Appendicectomy and cholecystectomy were among the procedures excluded.

RESULTS

Data from 1,708 patients from 35 National Health Service hospitals were analysed. The overall 30-day mortality rate was 14.8%. 'True' emergency laparotomies (ie those classified by the National Confidential Enquiry into Patient Outcome and Death as immediate or urgent) comprised 86.5% of cases. The mortality rate rose from 8.0% among expedited cases to 14.3% among urgent cases and to 25.7% among laparotomies termed immediate. Among the most common index procedures, small bowel resection exhibited the highest 30-day mortality rate of 21.1%. The presence of abdominal sepsis was associated with raised 30-day mortality (17.5% in the presence of sepsis vs 12.6%, p=0.027). Colorectal procedures comprised 44.3% and within this group, data suggest that mortality from laparotomy may be influenced by surgical subspecialisation.

CONCLUSIONS

This report of a large number of patients undergoing emergency laparotomy in the UK confirms a remarkably high mortality by modern standards across the range. Very few pathologies or procedures can be considered anything other than high risk. The need for routine consultant involvement and critical care is evident, and the case distribution helps define the surgical skill set needed for a modern emergency laparotomy service. Preliminary data relating outcomes from emergency colonic surgery to surgical subspecialty require urgent further study.

Current UK practice in emergency laparotomy

Introduction

Emergency laparotomy is a common procedure, with 30,000–50,000 performed annually in the UK. This large scale study reports the current spectrum of emergency laparotomies, and the influence of the surgical procedure, underlying pathology and subspecialty of the operating surgeon on mortality.

Methods

Anonymised data on consecutive patients undergoing an emergency laparotomy were submitted for a three-month period. The primary outcome measure was unadjusted 30-day mortality. Appendicectomy and cholecystectomy were among the procedures excluded.

Results

Data from 1,708 patients from 35 National Health Service hospitals were analysed. The overall 30-day mortality rate was 14.8%. ‘True’ emergency laparotomies (ie those classified by the National Confidential Enquiry into Patient Outcome and Death as immediate or urgent) comprised 86.5% of cases. The mortality rate rose from 8.0% among expedited cases to 14.3% among urgent cases and to 25.7% among laparotomies termed immediate. Among the most common index procedures, small bowel resection exhibited the highest 30-day mortality rate of 21.1%. The presence of abdominal sepsis was associated with raised 30-day mortality (17.5% in the presence of sepsis vs 12.6%, p=0.027). Colorectal procedures comprised 44.3% and within this group, data suggest that mortality from laparotomy may be influenced by surgical subspecialisation.

Conclusions

This report of a large number of patients undergoing emergency laparotomy in the UK confirms a remarkably high mortality by modern standards across the range. Very few pathologies or procedures can be considered anything other than high risk. The need for routine consultant involvement and critical care is evident, and the case distribution helps define the surgical skill set needed for a modern emergency laparotomy service. Preliminary data relating outcomes from emergency colonic surgery to surgical subspecialty require urgent further study.

Variations in mortality after emergency laparotomy: the first report of the UK Emergency Laparotomy Network

BACKGROUND

Emergency laparotomy is a common intra-abdominal procedure. Outcomes are generally recognized to be poor, but there is a paucity of hard UK data, and reports have mainly been confined to single-centre studies.

METHODS

Clinicians were invited to join an 'Emergency Laparotomy Network' and to collect prospective non-risk-adjusted outcome data from a large number of NHS Trusts providing emergency surgical care. Data concerning what were considered to be key aspects of perioperative care, including thirty-day mortality, were collected over a 3 month period.

RESULTS

Data from 1853 patients were collected from 35 NHS hospitals. The unadjusted 30 day mortality was 14.9% for all patients and 24.4% in patients aged 80 or over. There was a wide variation between units in terms of the proportion of cases subject to key interventions that may affect outcomes. The presence of a consultant surgeon in theatre varied between 40.6% and 100% of cases, while a consultant anaesthetist was present in theatre for 25-100% of cases. Goal-directed fluid management was used in 0-63% of cases. Between 0% and 68.9% of the patients returned to the ward (level one) after surgery, and between 9.7% and 87.5% were admitted to intensive care (level three). Mortality rates varied from 3.6% to 41.7%.

CONCLUSIONS

This study confirms that emergency laparotomy in the UK carries a high mortality. The variation in clinical management and outcomes indicates the need for a national quality improvement programme.

Out-of-theatre tracheal intubation: prospective multicentre study of clinical practice and adverse events

BACKGROUND

Tracheal intubation is commonly performed outside the operating theatre and is associated with higher risk than intubation in theatre. Recent guidelines and publications including the 4th National Audit Project of the Royal College of Anaesthetists have sought to improve the safety of out-of-theatre intubations.

METHODS

We performed a prospective observational study examining all tracheal intubations occurring outside the operating theatre in nine hospitals over a 1 month period. Data were collected on speciality and grade of intubator, presence of essential safety equipment and monitoring, and adverse events.

RESULTS

One hundred and sixty-four out-of-theatre intubations were identified (excluding those where intubation occurred as part of the management of cardiac arrest). The most common indication for intubation was respiratory failure [74 cases (45%)]. Doctors with at least 6 month's experience in anaesthesia performed 136 intubations (83%); consultants were present for 68 cases (41%), and overall a second intubator was present for 94 procedures (57%). Propofol was the most common induction agent [124 cases (76%)] and 157 patients (96%) received neuromuscular blocking agents. An airway rescue device was available in 139 cases (87%). Capnography was not used in 52 cases (32%). Sixty-four patients suffered at least one adverse event (39%) around the time of tracheal intubation.

CONCLUSIONS

Out-of-theatre intubation frequently occurs in the absence of essential safety equipment, despite the existing guidelines. The associated adverse event rate is high.

Determinants of outcome in critically ill octogenarians after surgery: an observational study

BACKGROUND

The population in the UK is growing older and the number of elderly patients cared for on intensive care units (ICU) is increasing. This study was designed to identify risk factors for mortality in critically ill patients of >80 yr of age after surgery.

METHODS

We identified 275 patients, aged 80 yr or greater, admitted to the ICU after surgery. After exclusions, 255 were selected for further analysis. Multivariate analysis was then performed to determine the covariates associated with hospital mortality.

RESULTS

The overall ICU and hospital mortality was 20.4% and 33.3%, respectively. Patients who received i.v. vasoactive drugs on days 1 and 2 had hospital mortality of 54.4% and 60.5%, respectively. Multivariate analysis showed that requirement for i.v. vasoactive drugs within the first 24 h on ICU [odds ratio (OR) 4.29; 95% CI, 2.35-7.84, P<0.001] and requirement for i.v. vasoactive drugs for a further 24 h (OR 3.63; 95% CI, 1.58-8.37, P<0.01) were associated with hospital mortality. The requirement for i.v. vasoactive drugs was also strongly associated with hospital mortality in all the subgroups studied (elective surgery, emergency surgery, and emergency laparotomy).

CONCLUSIONS

For patients aged 80 yr and more, admitted to ICU after surgery, the requirement for i.v. vasoactive drugs in the first and second 24 h was the strongest predictor of hospital mortality.

Traumatic pulmonary pseudocysts

We describe a case of a 19-year-old man who developed traumatic pulmonary pseudocysts after a rollover road traffic crash. These were associated with significant pulmonary haemorrhage requiring a period of mechanical ventilation, but resolved without specific intervention. Review of the literature confirms that this rare complication of blunt chest trauma occurs usually in young adults and, although normally benign, can be associated with life-threatening haemoptysis and secondary infection.

Monitoring patients during anaesthesia for radiological procedures

The past year has seen a number of reports discussing the future possibilities of image-guided surgery and interventional radiology. One of the most exciting developments is intra-operative magnetic resonance imaging. The anaesthesiologist plays a central role in these developments, ensuring that patients undergoing procedures in the radiology department are adequately monitored and safely maintained.

The effect of intravenous dexmedetomidine premedication on the dose requirement of propofol to induce loss of consciousness in patients receiving alfentanil

Dexmedetomidine reduces the dose requirements for opioids and anaesthetic agents. We conducted a single-centre, open-label, noncomparative phase II study of the effect of intravenous dexmedetomidine on the dose requirement of propofol to induce loss of consciousness in 49 ASA I and II patients. The initial dexmedetomidine infusion scheme was reduced twice because of adverse events. Forty patients who received the final infusion scheme were randomly allocated to receive one of five stepped propofol infusions; loss of consciousness was assessed after 21 min. The ED50 for the final infusion rate of propofol to suppress consciousness was 3.45 mg x kg(-1) x h(-1) (95% CL 2.7-4.2): ED95 was 6.68 mg x kg(-1) x h(-1) (95% CL 5.1-19.1), EC50 was 1.69 microg x ml(-1) (95% CL 0.95-2.5) and EC95 was 5.7 microg x ml(-1) (95% CL 3.2 to > 10). Our final dose of dexmedetomidine of 0.63 microg x kg(-1) caused a reduction in the overall concentration and dose of propofol required to produce loss of consciousness, but no significant shift in the dose-response curve compared with other studies.

Magnetic resonance imaging and P300 (event-related auditory evoked potentials) in the assessment of postoperative cerebral injury following coronary artery bypass graft surgery

Cerebral injury following coronary artery bypass grafting (CABG) surgery was investigated with magnetic resonance imaging (MRI) and P300, a long-latency endogenous evoked potential associated with psychological processing of stimulus information. Twelve patients were studied before and after surgery. Prior to surgery, MRI abnormalities were found in all but one patient. After surgery, five patients had new abnormalities, mainly deep white-matter lesions (DWML). Postoperative P300 latency was significantly increased in six patients. P300 topographical distribution showed a shift from predominantly posterior cerebral regions to frontal regions in most patients. Postoperative P300 and MRI deficits were found in three of the five patients. One of the patients with marked MRI change (DWML in caudate nucleus) did not show P300 deficit.

Feasibility of day case laparoscopic cholecystectomy in unselected patients

The feasibility of day case laparoscopic cholecystectomy was assessed in unselected patients using a standard anaesthetic protocol. Postoperative pain and nausea were assessed at 6 and 24 h postoperatively (visual analogue scale, range 0-10). Thirty-two patients were studied (23 female, 9 male, mean age 49.6 years). The mean duration of surgery was 68 min. At 6 h after surgery, 10 patients (31%) had no pain at rest. For the group as a whole, the median pain score was 3 at rest (range 0-6), 4 on movement (0-9), and 5 on coughing (0-9) and eight patients (25%) were nauseated. At 24 h, 15 (46.9%) had no pain at rest. For the group as a whole, the median pain score was 1 at rest (0-7), 3 (0-6) on movement and 3 on coughing (0-9). The same eight patients were nauseated. Ten patients (31.3%) were judged fit for discharge at 6 h, and 28 (87.5%) by 24 h. There was no statistical difference in mean age or duration of surgery in those judged fit for early discharge compared to the study group as a whole. Nausea was an important factor in those unfit for discharge at 24 h. Selection criteria might improve these figures. From the results of our study, 24 h admission is a more realistic goal and will be suitable for most patients requiring laparoscopic cholecystectomy.

Magnetic resonance imaging and neuropsychological changes after coronary artery bypass graft surgery: preliminary findings

Cerebral morbidity is a problem after cardiac surgery. Although neuropsychological tests and imaging techniques have been applied to cardiac patients, the relationship between them has not been considered. In the preliminary investigation, we studied 15 patients (11 male, mean age 59 years) having coronary artery bypass graft (CABG) surgery. Before surgery, patients had magnetic resonance (MR) imaging and neuropsychological assessment with a battery of 10 tests. During surgery, cardiopulmonary bypass was maintained at 28 degrees C with a flow rate of 2.4 L/m2/min-1 and at a mean arterial pressure of 50-70 mm Hg. Bubble or membrane oxygenators with in-line filters were used. Arterial blood gases were maintained using a pH-stat protocol. Fourteen of the 15 patients showed MR abnormalities before surgery. One week after surgery, four patients had additional MR changes. Six patients had significant postoperative neuropsychological deficit in memory (verbal and nonverbal) and attention. The four patients with new MR abnormalities all had significant neuropsychological deficit. In addition to corroborating previous observations that a high proportion of patients undergoing elective CABG have MR abnormalities before surgery, these preliminary data suggest a promising concordance between structural brain changes and cerebral function after CABG.

Induction of microcurrents in critically ill patients in magnetic resonance systems

OBJECTIVE

To determine whether electric current can be induced in intracardiac catheters, thermistor wires and pacing electrodes in patients during magnetic resonance imaging (MRI).

DESIGN

Prospective laboratory study.

SETTING

Postgraduate medical school hospital.

SUBJECTS

A sheep heart model.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Voltage generated by saline 0.9% flowing through a magnetic field and distribution of current from a catheter tip within a sheep heart model were measured in a 0.15 Tesla MRI system. Resistance of loops formed by pacing wires, a pacing electrode, and a thermistor wire were measured in saline 0.9%. Effects of rapidly changing magnetic fields and the movement of the beating heart on epicardial pacing wires were calculated theoretically. A flow of 200 mL/min of saline 0.9% induced a current of 0.1 microampere (microA) (at 0.15 Tesla). From magnetic resonance images we derived a current density of approximately 0.004 microA/mm2 (at 0.15 Tesla). Internal resistance of pacing catheters and thermistor wires was > 1 megaohm (M omega). The maximum currents calculated (for a higher field strength of 1.5 Tesla) in a circuit formed by epicardial pacing wires were 80 microA, induced by the beating heart moving the wires through the magnetic field and 46 microA, induced by the rapidly changing magnetic fields.

CONCLUSIONS

Current generated by flow of conducting fluid should be safe. Pacing catheters and thermistor wires should be safe if well insulated and disconnected from external electric connections. However, current induced in epicardial pacing wires may be a hazard, and precautions should be taken. External wire tips must be separated, insulated, and coiled to lie along the axis of the magnetic field. Electrocardiography is required, and defibrillation equipment should be available.

In vivo fluorine-19 magnetic resonance spectroscopy of cerebral halothane in postoperative patients: preliminary results

This study reports the use of 19F MRS to study halothane in the brain of eight patients recovering from halothane anesthesia of short duration. Resonances attributable to halothane were observed up to 90 min after withdrawal of the anesthetic agent. The signal-to-noise ratio for an unlocalized spectrum acquired using a 6 cm surface coil was typically 20 with data collection times of 2 min. In seven patients a single resonance was seen with a mean (+/- SD) chemical shift of +43.3 (+/- 1.8) ppm, referenced to NaF at 0 ppm. This resonance exhibited a T1 value of between 0.5 and 1 s, and a T2* (estimated from the linewidth of the resonance) between 3.5 and 10 ms. In one patient two resonances were observed with chemical shifts of +38 and +41 ppm. Because we cannot exclude the possibility that this was due to field inhomogeneity, the significance of the last finding is uncertain. However, phantom studies show that the chemical shift of halothane in different environments (such as water, olive oil, methanol, and lecithin) can vary to an extent that accounts for the two resonances seen in our patient. These results demonstrate the feasibility of in vivo 19F MRS studies of fluorinated volatile agents in humans. The potential for clinical 19F MRS of fluorinated anesthetics is discussed.

A 31P and 1H-NMR investigation in vitro of normal and abnormal human liver

Spectral changes in human hepatic tumours and possible systemic effects of tumour on host liver were assessed by 31P and 1H in vitro NMR spectroscopy. The 1H and 31P spectra from liver tumour biopsies showed significant elevation in phosphoethanolamine, phosphocholine, taurine, citrate, alanine, lactate and glycine, and significant reduction in GPE (glycerophosphoethanolamine), GPC (glycerophosphocholine), creatine and threonine compared to histologically normal tissue. 31P-NMR spectra obtained from histologically normal tissue within tumour-bearing livers showed significant elevation in phosphoethanolamine and phosphocholine compared to data from liver biopsies from nontumour-bearing patients (pancreatitis). These results suggest that alterations in membrane metabolism in host liver can be detected by 31P-NMR.

Capnothorax: implications for the anaesthetist

Ten patients underwent a laparoscopic surgical technique for thoracic and cervical dissection of the oesophagus during oesophagogastrectomy. Thoracotomy was avoided with potential benefits to the patient. To facilitate surgical access the right lung was collapsed using a double-lumen bronchial tube and carbon dioxide was insufflated into the right pleural cavity to compress the lung. Changes in haemodynamic and respiratory variables occurred. In the majority of the patients airway pressure and end-tidal CO2 increased, despite alterations in ventilation. In five patients systolic blood pressure decreased suddenly by between 15 and 35 mmHg, and in four patients SpO2 decreased to 91% or less, despite an FIO2 of 1.0. If carbon dioxide was insufflated too fast, or the lung failed to deflate adequately, the clinical picture was that of a tension pneumothorax. One patient developed surgical emphysema and a contralateral pneumothorax. Postoperatively two patients had recurrent laryngeal nerve damage. Suggestions are made to minimise the changes in haemodynamic and respiratory variables during carbon dioxide insufflation into the thorax.

Proton spectroscopy of the neonatal brain following hypoxic-ischaemic injury

Proton magnetic resonance spectroscopy was used to examine, within the first month of life, the brains of 11 infants born at term--10 with signs of hypoxic-ischaemic encephalopathy (HIE) and one who was neurologically normal at birth. All the infants had peak resonances on their spectra which could be assigned to N-acetyl-aspartase (NAA), choline-containing compounds (Cho) and creatine plus phosphocreatine (Cr). When neurodevelopmental outcome at one year was correlated with initial spectroscopy findings, the NAA/Cho and NAA/Cr ratios reflected clinical outcome. This study suggests that proton spectroscopy not only provides new information about biochemical changes occurring in the brains of infants with HIE, but also may help to predict outcome within the first month of life.

Magnetic resonance for the anaesthetist. Part II: Anaesthesia and monitoring in MR units

Anaesthetists are increasingly involved in patient care during magnetic resonance imaging and spectroscopy. This paper describes a system which has been developed for the management of critically ill patients and the conduct of anaesthesia in a magnetic resonance unit with a 1.6 tesla whole body magnet. Difficulties which arise from working in a confined space in a high magnetic field are highlighted. Different approaches to anaesthesia, sedation and the modification of equipment for use in this environment are reviewed. The problems associated with patient monitoring within a magnetic field are discussed and some solutions are suggested. A transport system for critically ill patients is described and a protocol for management is outlined.

Magnetic resonance for the anaesthetist. Part I: Physical principles, applications, safety aspects

Anaesthetists are being increasingly involved in magnetic resonance (MR) procedures, both in patient care and as a research tool. This paper outlines the physical basis of nuclear magnetic resonance and describes its application in magnetic resonance imaging and spectroscopy. Principles of magnet design and safety relevant to anaesthetic practice in a magnetic resonance environment are discussed and guidelines for anaesthetic practice suggested. Some recent clinical magnetic resonance studies of anaesthetic interest are reviewed.

Proton MR spectroscopy of the brain in infants

Proton magnetic resonance spectroscopy (MRS) was used to study the brain of 2 normal and 15 abnormal infants aged from 33 weeks postmenstrual age (PMA) to 14 months postnatal age. Eleven of the infants were examined on at least two occasions. The principal clinical diagnoses in the abnormal infants were perinatal ischemic and hemorrhagic brain injury. All proton spectra demonstrated peaks that were assigned to N-acetylaspartate (NAA), choline containing compounds (Cho), and creatine plus phosphocreatine (Cr). The NAA/Cho and NAA/Cr ratios increased with age, while the Cho/Cr ratio decreased with age in the majority of infants. The NAA/Cho ratio was generally lower in abnormal infants, but the difference was not apparent before 40 weeks (PMA). This ratio was lowest in infants with the severest degree of neurological abnormality. Proton and phosphorus MRS was compared in seven infants. In those with severe brain lesions, early phosphorus spectra were abnormal. On follow-up the phosphorus spectra became normal, but the proton spectra showed persistently low NAA/Cho and NAA/Cr ratios. Proton MRS provides new information that may be complementary to phosphorus MRS in the diagnosis and monitoring of brain development in normal and neurologically damaged infants.

Proton MR spectroscopy of intracranial tumours: in vivo and in vitro studies

Proton magnetic resonance spectroscopy (1H MRS) was used to investigate intracranial tumours in vitro and in vivo. Biopsy specimens were studied from 47 patients, 11 of whom were also examined in vivo. Analysis was based on the signals from N-acetylaspartate (NAA), phosphocreatine plus creatine (Cr), choline-containing compounds (Cho), alanine (Ala), and lactate. Biopsy data from 26 astrocytomas showed that the NAA/Cr ratio differs significantly in all grades from its value in normal white matter and that the Cho/Cr ratio differs significantly in grade IV tumours from its value in the other grades. Meningiomas have an unusually high Ala/Cr ratio. Spectra obtained in vivo are consistent with in vitro results from the same patients, and their lactate signal provides additional information about abnormal metabolism. We conclude that 1H MRS has a clear role in the diagnosis and biochemical assessment of intracranial tumours and in the evaluation and monitoring of therapy.

Proton MR spectroscopy in herpes simplex encephalitis: assessment of neuronal loss

We present here the case of an 11-year-old boy with herpes simplex encephalitis diagnosed on the basis of clinical features, serology, and response to acyclovir, who relapsed after 3 weeks of therapy. In vivo proton magnetic resonance spectroscopy (1H MRS) of the brain, at 8 and 16 weeks after the onset of symptoms, showed abnormalities, most prominently a reduction in the N-acetylaspartate/choline ratio. The role of 1H MRS in assessing disease activity is discussed.