Anaesthesia techniques

M. Ganter and A. Zollinger, Continuous intravascular blood gas monitoring development, current techniques, and clinical use of a commercial device. Bri. J. Anaesthesia 91, 397-407 (2003). 

In situ techniques suffer the disadvantage that the animal is anaesthetised for the duration of the experiment. Surgery and anaesthesia change several physiological factors that can alter drug absorption characteristics. Anderson et al. [117] found the ABL thickness in laparotomised rats to be higher than in conscious non-laparotomised rats. Yuasa et al. [118] reported that... 

Lignocaine injections are indicated for production of local or regional anaesthesia by infiltration techniques such as percutaneous injection, peripheral nerve block, spinal or subarachnoid block. 

Fry RA, Henderson J. Local anaesthesia for eye surgery the periocular technique. Anaesthesia 1989 45 14-17. 

In selected cases the full range of techniques of local and regional anaesthesia may be used, including extradural and intrathecal morphine (p. 360). 

A continuous intravenous infusion of propofol can be used to maintain anaesthesia. This technique of total intravenous anaesthesia is becoming more popular because the quality of recovery may be better than after inhalational anaesthesia. 

Intravenous. A double cuff is applied to the arm, inflated above arterial pressure after elevating the limb to drain the venous system, and the veins filled with local anaesthetic, e.g. 0.5-1% lidocaine without adrenaline (epinephrine). The arm is anaesthetised in 6-8 min, and the effect lasts for up to 40 min if the cuff remains inflated. The cuff must not be deflated for at least 20 minutes. The technique is useful in providing anaesthesia for the treatment of injuries speedily and conveniently, and many patients can leave hospital soon after the procedure. The technique must be meticulously conducted, for if the full dose of local anaesthetic is accidentally suddenly released into the general circulation severe toxicity and even cardiac arrest may result. Bupivacaine is no longer used for intravenous regional anaesthesia as cardiac arrest caused by it is particularly resistant to treatment. Patients should be fasted and someone skilled in resuscitation must be present. 

Extradural (epidural) anaesthesia is used in the thoracic, lumbar and sacral (caudal) regions. Lumbar epidurals are used widely in obstetrics and low thoracic epidurals provide excellent analgesia after laparotomy. The drug is injected into the extradural space where it acts on the nerve roots. This technique is less likely to cause hypotension than spinal anaesthesia. Continuous analgesia is achieved if a local anaesthetic, often mixed with an opioid, is infused through an epidural catheter. 

Epidural local anaesthesia provides the most effective pain relief, but the technique should only be undertaken after adequate training. In the UK, only anaesthetists insert epidural anaesthetics. 

High blood glucose concentration matters little over short periods, except in the critically ill. The programme for control should be agreed between anaesthetist and physician whenever diabetic patients must undergo general anaesthesia or modify their diets. There are many different techniques that can give satisfactory results. 

Burmeister MA, Brauer P, Wintruff M, Graefen M, Blanc I, Standi TG. A comparison of anaesthetic techniques for shock wave lithotripsy the use of a remifentanil infusion alone compared to intermittent fentanyl boluses combined with a low dose propofol infusion. Anaesthesia 2002 57(9) 877-81. 

Dear GD, Hammerton M, Hatch DJ, Taylor D. Anaesthesia and intra-ocular pressure in young children. A study of three different techniques of anaesthesia. Anaesthesia 1987 42(3) 259-65. 

This technique is similar to spinal anaesthesia. It is technically more difficult but is considered to be safer and has largely replaced spinal anaesthesia. 

Topical anaesthesia prior to venepuncture may be necessary. This technique with EMLA (eutectic mixture of local anaesthetics) cream may be used by radiographers under patient group directions. See Chapter 12. 

Techniques range from inhltraiion of anac-sthctic around a single nerve (e.g. dental anaesthesia) to epidural and spinal anaesthesia. In. spinal anaesthesia (intrathecal block) a drug is injected into the ccrebrospina) fluid in the subarachnoid space. In epidural anaesthesia the anaesthetic is injected outside the dura. Spinal anaesthesia is technically far easier to produce than cpidural anaesthesia, but the latter technique virtually eliminates the postanaesihetic complications such as headache. 

Two reviews have discussed the use of opioids and propofol in anaesthesia, their pharmacokinetic and pharmacodynamic interactions, and administration and monitoring techniques. ... 

The goal of human error quantification is to produce error probabilities, building on task analysis and error identification techniques to provide a probabilistic risk assessment (PRA). This provides numerical estimates of error likelihood and of the probability of overall likelihood of system breakdown. Quantification of error is the most difficult aspect of HRA, often heavily reliant on expert judgement, rather than the more rigorous approach of actual observation and recording of error frequencies. Such techniques are little used in healthcare but have been successfully applied to anaesthesia (Pate-Cornell and Bea, 1992). Nevertheless, some hospital tasks, such as blood transfusion, are highly structured and the quantification of errors probabilities would seem to be eminently feasible (Lyons et al, 2004). 

As success is variable, the production of tetraploid mussels requires ploidy testing, which can be made by flow cytometry. Early-stage batches have to be tested destructively on small samples of larvae. In BLUE SEED project trials, the technique produced tetraploidy in D-larvae in five separate experiments, covering both M. edulis and M. galloprovincialis, with tetraploid percentages between 18% and >60%, based on samples of 50-200 ground larvae. Later, non-destructive tests could be made on juveniles and adults by biopsy under MgCL anaesthesia. It was found that... 

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