Safer epidural and spinal connectors.

Inadvertent cross-connection of epidural local anaesthetic delivery systems with intravenous lines can cause significant morbidity and even death. Inadvertent intrathecal injection of toxic intravenous drugs has already led to many deaths. If epidural and spinal systems had the standard Luer lock connection reversed the problem would be prevented. The practical implications of this idea are explored. Patient safety would be enhanced if this system were adopted.

Organisational failures in urgent and emergency surgery. A potential peri-operative risk factor.

Medical error is an important cause of morbidity and mortality. Organisational failure in the pre-operative period has been associated with catastrophic outcome. Little information is available regarding peri-operative organisational problems. The incidence and nature of organisational failure before urgent and emergency surgery in a district general hospital was studied prospectively in 159 cases over a 30-day period. Organisational failure affected more than half of the cases overall, but varied in both its incidence and its complexity between surgical disciplines. Various causative factors were identified, e.g. 8% of cases were subject to delay due to clinical emergencies. The median [range] time required to rectify the problems was 115 [5-750] min. A consultant anaesthetist and surgeon were present in 30 and 20% of cases, respectively. Difficulty with the preparation of patients for emergency surgery is an important but underevaluated cause of medical error that may put patients at risk.

Extent of laminin-5 assembly and secretion effect junctional epidermolysis bullosa phenotype.

Junctional epidermolysis bullosa (JEB) is an autosomal recessive skin blistering disease with both lethal and nonlethal forms, with most patients shown to have defects in laminin-5. We analyzed the location of mutations, gene expression levels, and protein chain assembly of the laminin-5 heterotrimer in six JEB patients to determine how the type of genetic lesion influences the pathophysiology of JEB. Mutations within laminin-5 genes were diversely located, with the most severe forms of JEB correlating best with premature termination codons, rather than mapping to any particular protein domain. In all six JEB patients, the laminin-5 assembly intermediates we observed were as predicted by our previous work indicating that the alpha3beta3gamma2 heterotrimer assembles intracellularly via a beta3gamma2 heterodimer intermediate. Since assembly precedes secretion, mutations that disrupt protein-protein interactions needed for assembly are predicted to limit the secretion of laminin-5, and likely to interfere with function. However, our data indicate that typically the most severe mutations diminish mRNA stability, and serve as functional null alleles that block chain assembly by resulting in either a deficiency (in the nonlethal mitis variety) or a complete absence (in lethal Herlitz-JEB) of one of the chains needed for laminin-5 heterotrimer assembly.

Topical anaesthesia for cataract surgery.

First, do no harm. We believe that the analgesia provided by topical anaesthetic is adequate for small-incision cataract surgery and does not compromise the safety of the surgery. In addition, the lack of amaurosis is ideal for day-case surgery, which itself is increasingly popular. If preventable, why not prevented? The greatest attraction of topical anaesthesia is its complete absence of the complications described for injectional local anaesthetic techniques. We therefore recommend that our colleagues consider topical anaesthetic for patients undergoing small-incision cataract surgery under local anaesthesia. Our policy for the past 3 years has been to use only topical or general anaesthetics for cataract surgery.

Effect of caffeine on respiratory and quadriceps muscle contractility in man

A cafeína pontencializa a funçäo do músculo esquelético in vitro, mas há poucos dados sobre seu efeito no homem. Foram examinados os efeitos de dose máxima tolerada de cafeína (600mg) na funçäo dos músculos respiratórios e quadríceps em seis pessoas normais (cinco homens, idade 25-41 anos), como é mostrado a seguir: 1) Em estudo sobre o efeito agudo no músculo quadríceps femoris, seis pessoas realizaram quatro contraçöes máximas voluntárias isométricas (MVC). A seguir, foram produzidas contraçöes tetânicas isométricas involuntárias com estimulaçäo elétrica de 20Hz, aplicada através de elétrodos de superfície, com voltagem suficiente para alcançar 30 por cento MVC. Este estímulo constante foi repetido dez vezes, a intervalos de cinco minutos, antes de cafeína ou placebo ter sido ingerido em cada um dos quatro dias de estudo. Trinta minutos após, foram medidas outras dez estimulaçöes elétricas idênticas às descritas anteriormente e quatro MVCs. 2) Em estudo controlado cruzado dos efeitos da cafeína sobre a força de músculos respiratórios e da força e fadiga do quadríceps femoris, quatro pessoas ingeriram cafeína ou placebo em quatro dias de estudo. Uma hora após, cada sujeito realizou quatro pressöes bucais inspiratórias e expiratórias máximas (PImáx & PEmáx) e mediu-se duas vezes a força produzida por estimulaçäo elétrica com freqüências de dez, 20, 30, 50 e 100Hz. Entäo, foi produzida fadiga por estimulaçäo repetitiva durante dois minutos com freqüência de 20Hz, ciclo de 50 por cento e força inicial de 30 por cento MVC. Um e dez minutos após, repetiu-se a curva freqüência-força. Näo houve diferença significativa nas MVC, PImáx e PEmáx produzidas após cafeína e placebo. Cafeína näo teve efeito significativo no desenvolvimento da fadiga (medida por amplitude das contraçöes e máxima taxa de relaxamento) e na sua recuperaçäo. No quadríceps femoris, encontramos pequeno mas estatisticamente significativo aumento da força de contraçäo estimulada eletricamente com baixa freqüência (20Hz).

Risk information supplied by obstetric anaesthetists in Britain and Ireland to mothers awaiting elective caesarean section.

Mothers presenting for elective caesarean section may be offered the choice of regional or general anaesthesia. Their decision requires sensible information on the risks and benefits of each technique. In order to determine the level of consensus that exists among doctors in Britain and Ireland concerning the options offered and risk information provided for such patients, a questionnaire comprising a fictitious case history and a list of sample statements was mailed to 613 members of the Obstetric Anaesthetists' Association. 523 (85.3%) replied of whom 63% would advise surgery under regional anaesthesia, 32% after full discussion would allow the mother a choice of techniques, while only 5% would advise general anaesthesia. There was broad agreement on what information should be provided, with a consensus value of 0.60 or more in 15 of 20 statements.

The effects of beta 2-agonists and caffeine on respiratory and limb muscle performance.

The possibility that respiratory muscle function may be improved by drug therapy is of clinical importance, but remains controversial. A series of studies concerning the effects of maximally tolerated dosages of terbutaline, tulobuterol (a new beta 2-agonist) and caffeine on respiratory muscle strength and limb muscle strength and endurance were undertaken in normal subjects. Drugs were administered orally, 2 h before study. Caffeine produced a small but statistically significant increase in the stimulated contraction force at 20 Hz, and a small beneficial effect on recovery from a fatiguing protocol; maximum voluntary contraction force of the quadriceps was increased by 3.8%. Terbutaline and tulobuterol had no beneficial effects on either respiratory or limb muscle function. We conclude that conventional dosages of these bronchodilator drugs do not greatly affect skeletal muscle performance.

Prospects for estimating nucleotide divergence with RAPDs.

The technique of random amplification of polymorphic DNA (RAPD), which is simply polymerase chain reaction (PCR) amplification of genomic DNA by a single short oligonucleotide primer, produces complex patterns of anonymous polymorphic DNA fragments. The information provided by these banding patterns has proved to be of great utility for mapping and for verification of identity of bacterial strains. Here we consider whether the degree of similarity of the banding patterns can be used to estimate nucleotide diversity and nucleotide divergence. With haploid data, fragments generated by RAPD-PCR can be treated in a fashion very similar to that for restriction-fragment data. Amplification of diploid samples, on the other hand, requires consideration of the fact that presence of a band is dominant to absence of the band. After describing a method for estimating nucleotide divergence on the basis of diploid samples, we summarize the restrictions and criteria that must be met when RAPD data are used for estimating population genetic parameters.

Oxygen desaturation after dental anaesthesia.

The incidence of oxygen desaturation (less than 91%) was measured by pulse oximetry during recovery from outpatient dental anaesthesia in 120 ASA grade I and II children. Alternate cases were given supplementary oxygen 5 litre min-1 by mask. Eighteen of 60 children (30%) given air and 14 of 60 (23%) given oxygen exhibited desaturation (P greater than 0.05). Desaturation was more likely to occur if the child was cared for during recovery by locum rather than permanent nursing staff: 22 of 64 (34%) compared with 10 of 56 (18%) (P less than 0.05). It is concluded that significant desaturation is common after brief dental anaesthesia, that the incidence of desaturation is not reduced significantly by supplementary oxygen and that careful supervision of patients by experienced recovery room staff is necessary after dental anaesthesia.