NICE guidance on antibiotic prophylaxis to prevent infective endocarditis: a survey of clinicians' attitudes

BACKGROUND

Since the introduction of the National Institute for Health and Clinical Excellence (NICE) guideline (CG064) in 2008 recommending cessation of antibiotic prophylaxis (AP) against infective endocarditis (IE), low level prescribing persists in the UK and is a potential reason why there has been no significant change in the general upward trend in cases of IE.

AIM

To undertake a survey of dentists (Ds), cardiologists and cardiothoracic surgeons (C/CTSs) and infection specialists (ISs) to determine why this might be the case.

DESIGN

Internet questionnaire-based survey.

METHODS

A questionnaire was distributed by email to specialists via UK national societies.

RESULTS

A total of 1168 responses were received. All the specialist groups are aware of the guideline (99%). Ds are broadly satisfied, whereas C/CTSs are not. Most Ds follow the NICE guidance (87%), whereas many C/CTSs (39%) do not; ISs adopt a middle course (56%). Even amongst Ds, a significant proportion believe that patients with a prosthetic heart valve (25%) or previous history of IE (38%) should receive AP. A total of 36% of Ds have prescribed AP since March 2008 and many have undertaken procedures where AP has been prescribed by someone else. The majority of respondents (65%) feel that more evidence is required, preferably in the form of a randomized controlled trial.

CONCLUSION

Many patients perceived to be at high risk of IE are still receiving AP in conflict with current NICE guidance.

A novel technique for nonvolitional assessment of quadriceps muscle endurance in humans

Assessment of quadriceps endurance is of interest to investigators studying human disease. We hypothesized that repetitive magnetic stimulation (rMS) of the intramuscular branches of the femoral nerve could be used to induce and quantify quadriceps endurance. To test this hypothesis, we used a novel stimulating coil to compare the quadriceps endurance properties in eight normal humans and, to confirm that the technique could be used in clinical practice, in eight patients with advanced chronic obstructive pulmonary disease (COPD). To validate the method, we compared in vivo contractile properties of the quadriceps muscle with the fiber-type composition and oxidative enzyme capacity. We used a Magstim Rapid2 magnetic nerve stimulator with the coil wrapped around the quadriceps. Stimuli were given at 30 Hz, a duty cycle of 0.4 (2 s on, 3 s off), and for 50 trains. Force generation and the surface electromyogram were measured throughout. Quadriceps twitch force, elicited by supramaximal magnetic stimulation of the femoral nerve, was measured before and after the protocol. Quadriceps muscle biopsies were analyzed for oxidative (citrate synthase, CS) and glycolytic (phosphofructokinase, PFK) enzyme activity and myosin heavy chain isoform protein expression. The time for force to fall to 70% of baseline (T70) was shorter in the COPD group than the control group: 55.6 ± 26.0 vs. 121 ± 38.7 s ( P = 0.0014). Considering patients and controls together, positive correlations were observed between T70 and the proportion of type I fibers ( r = 0.68, P = 0.004) and CS-to-PFK ratio (CS/PFK) ( r = 0.67, P = 0.005). We conclude that quadriceps endurance assessed using rMS is feasible in clinical studies.

Adaptive servo-ventilation and deadspace: effects on central sleep apnoea

Central Sleep Apnoea (CSA) occurs commonly in heart failure. Adaptive servo-ventilation (ASV) and deadspace (DS) have been shown in research settings to reverse CSA. The likely mechanism for this is the increase of PaCO(2) above the apnoeic threshold. However the role of increasing FiCO(2) on arousability remains unclear. To compare the effects of ASV and DS on sleep and breathing, in particular effects on Arousal Index (ArI), ten male patients with heart failure and CSA were studied during three nights with polysomnography plus measurements of PetCO(2). The order of the interventions control (C), ASV and DS was randomized. ASV and DS caused similar reductions in apnoea-hypopnoea index [(C) 30.0 +/- 6.6, (ASV) 14.0 +/- 3.8, (DS) 15.9 +/- 4.7 e h(-1); both P < 0.05]. However, DS was associated with decreased total sleep time compared with C (P < 0.02) and increased spontaneous ArI compared to C and ASV (both P < 0.01). Only DS was associated with increased DeltaPetCO(2) from resting wakefulness to eupnic sleep [(C) 2.1 +/- 0.9, (ASV) 1.3 +/- 1.0, (DS) 5.6 +/- 0.5 mmHg; P = 0.01]. ASV and DS both stabilized ventilation however DS application also increased sleep fragmentation with negative impacts on sleep architecture. We speculate that this effect is likely to be mediated by increased PetCO(2) and respiratory effort associated with DS application.

Right hemi-diaphragm paralysis following cardiac radiofrequency ablation

Diaphragm paralysis may occur after traumatic phrenic nerve injury. Here we report three patients in whom right hemi-diaphragmatic paralysis developed after cardiac radiofrequency ablation. We hypothesise that local focused thermal energy at the time of the ablation may have caused direct neuronal damage by axonal coagulation necrosis. The prognosis for this type of injury may be reasonably good; two of the three patients fully recovered diaphragm function by 1 year.

Acute effect of oral steroids on muscle function in chronic obstructive pulmonary disease

Prospective data to support the hypothesis that corticosteroids are a significant cause of muscle weakness in patients with chronic obstructive pulmonary disease (COPD) are lacking. The authors studied respiratory and quadriceps muscle function, using both volitional techniques and magnetic nerve stimulation, as well as measuring metabolic parameters during incremental cycle ergometry, in 25 stable COPD patients. The forced expiratory volume in one second was 37.6 +/- 21.4% predicted, before and after a 2-week course of o.d. prednisolone 30 mg. Quadriceps strength was also assessed in 15 control patients on two occasions. Only two patients met the British Thoracic Society definition of steroid responsiveness. There was no change either in sniff transdiaphragmatic pressure (pre: 96.8 +/- 19.7 cmH2O; post: 98.6 +/- 22.4 cmH2O) or in twitch transdiaphragmatic pressure elicited by bilateral anterolateral magnetic phrenic-nerve stimulation (pre: 16.8 +/- 9.1 cmH2O; post: 17.9 +/- 10 cmH2O). Quadriceps twitch force did not change significantly either in the steroid group (pre: 9.5 +/- 3.1 kg; post: 8.9 +/- 3.7 kg) or in the control patients (pre: 8.1 +/- 2.7 kg; post: 7.9 +/- 2.2 kg). There were no changes in either peak or isotime ventilatory and metabolic parameters during exercise. In conclusion, in stable patients with chronic obstructive pulmonary disease, a 2-week course of 30 mg prednisolone daily does not cause significant skeletal muscle dysfunction or alter metabolic parameters during exercise.

Facet joint osteomyelitis in a patient on long-term hemodialysis

Spinal osteomyelitis is a recognized complication in dialysis patients related to hematogenous spread of infection during bacteremia-septicemia. These episodes are often associated with sepsis due to temporary dialysis access. We describe the case of an unfortunate man whose osteomyelitis was located in the posterior facet joints. Such infection is rare and in the reviewed literature is usually associated with a more favorable outcome than described here.