Temporal artery biopsies: do they make the cut?

BACKGROUND AND AIMS: Temporal artery biopsy is the gold standard investigation for giant cell arteritis. Guidelines recommend that specimens should measure no less than 1 cm and ideally more than 2 cm in length, as this influences the likelihood of biopsy positivity. This audit investigates the extent to which temporal artery biopsies acquired in our hospital meet these guidelines. METHODS: Histopathology reports for all temporal artery biopsies performed at University Hospital Ayr between January 2011 and June 2013 were examined. RESULTS: Fifty-six temporal artery biopsy specimens showed a range in length from 0.5 cm to 3.1 cm, with a mean of 1.4 cm. Thirty-seven biopsies measured ≥1 cm (66%) and 13 were ≥2 cm (23%). Therefore, 19 samples (34%) did not meet the recommended standard. Just seven biopsies showed features of giant cell arteritis, with six of these measuring ≥1 cm in length (86%). CONCLUSION: The guidelines for temporal artery specimens are not being met at our centre. Furthermore, biopsies measuring ≥1 cm are much more common in the small group of positive results. This validates the minimum recommended biopsy length and displays the importance of achieving this standard. We suggest changes to increase the number of biopsies meeting these guidelines, improving the accuracy of this invasive test.

Comparison of the effects of four i.v. anaesthetic agents on polymorphonuclear leucocyte function.

Initial resistance of bacterial infection is mediated primarily by polymorphonuclear leucocytes (PMN). Anaesthetic agents have been reported to impair various aspects of PMN function. It is possible that the use of these agents to sedate critically ill patients may further compromise an already depressed host defence mechanism. A flow cytometric technique with fresh whole blood from 10 healthy volunteers was used. Phagocytic and respiratory burst activity of PMN incubated for 1 h with either propofol, thiopentone, midazolam or ketamine at both clinical plasma concentrations and 100 times this concentration were determined. Thiopentone at the higher concentration reduced both respiratory burst activity (mean peak channel 50.7 compared with control value of 77.6 (P < 0.0001)) and phagocytosis (mean peak channel 47.5 compared with 79.9 (P < 0.0001)). Ketamine at 100 times the clinical plasma concentration also reduced respiratory burst and phagocytosis, but this failed to reach statistical significance (P = 0.10 and P = 0.053, respectively). No significant depression occurred in the other groups. The results suggest that these i.v. anaesthetic agents, at clinically relevant concentrations, have minimal effects on PMN phagocytosis and oxygen free radical production. At higher concentrations thiopentone and ketamine may affect phagocytic function and thiopentone may impair intracellular cytolysis.

Are air inlets necessary with Haemaccel?

Haemaccel is often used for the resuscitation of shocked patients. It is common practice to introduce an air inlet into the plastic container to increase the flow rate. We investigated how much difference an air inlet made. We compared the flow rates with no air inlet, a single air inlet, a 2 x 2 cm hole (equivalent to multiple air inlets) and a pressure infusion cuff. Although the use of an air inlet compared with no air inlet reduced the time to infuse 500 ml by 27 s, the difference was only clinically significant over the final 100 ml. A pressure cuff produced the fastest flow, reducing the time by 68 s. Use of an air inlet, however, precludes subsequent use of a pressure cuff. We recommend that the practice of using air inlets for Haemaccel and other similarly packaged products is abandoned.

Comparison of HA-1A and E5 monoclonal antibodies to endotoxin in rats with endotoxaemia.

OBJECTIVE: To investigate the ability of two anti-endotoxin IgM antibodies (10 mg/kg) to prevent the hyperdynamic response induced by infusion of Escherichia coli rough mutant endotoxin core types R1 and R2 in rats. DESIGN: Randomised blind laboratory study. SETTING: University department of surgery. MATERIAL: 8 groups of 5 male Sprague-Dawley rats and 10 control animals. MAIN OUTCOME MEASURE: Percentage change in cardiac output during the period of observation. RESULTS: E5 provided significant protection against R1 (p = 0.04) but not against R2. HA-1A gave significant protection against R2 (p < 0.04) but not against R1. In clinical isolates of E. coli the R1 type predominates (about 70%). CONCLUSION: These results may reflect true differences in specificity between the antibodies, but there remains the possibility that these are non-specific effects. Further controls with irrelevant murine and humanized IgM monoclonal antibodies are in progress.

Evaluation of three portable suction devices.

Three portable suction devices were evaluated and compared with a wall-mounted vacuum driven suction unit. The Repro-med Res-Q-Vac, the Dräger Sujector 2000 and the Laerdal suction unit were assessed by measuring the time taken to aspirate 140 ml of mock gastric contents. The respective times for each device, expressed as mean and (range) were 7.39 (4.3-10.4), 8.6 (7.8-9.4) and 11.4 (9.4-12.6) s. These compare favourable with the Ohmeda suction unit (7.27 (6.2-8.9)). Each type of device has advantages and disadvantages when factors such as size, power supply and portability are considered, and each will be the most suitable for a particular situation.

Selective decontamination of the digestive tract in intensive care.

Nosocomial infection in intensive care unit (ICU) practice is a common problem and is associated with abnormal carriage of Gram-negative aerobic bacilli in the gastrointestinal tract, resulting in endogenous infections. Selective decontamination of the digestive tract (SDD) is a regimen aimed at preventing or eradicating this abnormal carriage. A large number of trials examining SDD in ICU practice have been published, the vast majority showing a significant reduction in the incidence of nosocomial, Gram-negative infection. However, the impact on morbidity and mortality is much less certain. A recent meta-analysis has suggested a 10-20% reduction in mortality (3-6% absolute difference) with SDD. A discussion of these results is presented together with potential criticisms of SDD.

Prevention of cardiovascular effects of endotoxaemia by monoclonal antibodies specific for core endotoxin.

Passive immunization with antibody to the core region of endotoxin (core lipopolysaccharide (LPS)) has been reported to reduce mortality in severe sepsis. A rat model of endotoxaemia that reproduces the hyperdynamic cardiovascular state seen in early sepsis was developed to test monoclonal antibodies specific for core LPS. A thermodilution technique of measuring cardiac output was adapted for use in rats. Twenty-five animals were anaesthetized and mechanically ventilated with monitoring of central venous pressure and mean arterial pressure. Fluid replacement was adjusted to maintain the central venous pressure. Controls (n = 10) and antibody-treated animals (n = 5) showed no significant change in cardiac output. Animals given 0.1 mg kg-1 R2 endotoxin over 1 h (n = 5) showed a significant rise in cardiac output of 65 per cent (P < 0.01). This was abolished in rats given both antibody and endotoxin (n = 5). This study provides evidence that a monoclonal antibody against core LPS abolishes the hyperdynamic state induced by endotoxin infusion.

Warming lignocaine to reduce pain associated with injection.

OBJECTIVE: To investigate the effect of warming lignocaine on the pain associated with subcutaneous injection. DESIGN: Double blind, randomised, crossover study. SETTING: Hospital clinic. SUBJECTS: 40 healthy volunteers. INTERVENTIONS: Subcutaneous injection with 1 ml of 1% lignocaine at 20 degrees C and 1 ml of 1% lignocaine at 37 degrees C. MAIN OUTCOME MEASURES: Pain assessed by linear analogue pain scores and subjects' comparison of pain on injection. RESULTS: 25 subjects (89%; 95% confidence interval 72% to 98%) thought that lignocaine at 20 degrees C was more painful and 3 (11%; 2% to 28%) thought that lignocaine at 37 degrees C was more painful (p < 0.0001); 12 subjects did not express a difference. Median pain score for injection at 20 degrees C was 11.00 and at 37 degrees C was 3.25 (p < 0.001). Median difference was 8.25 (4.00 to 13.50). CONCLUSIONS: The simple procedure of warming to 37 degrees C reduced the pain associated with subcutaneous injection of lignocaine.