Minimally Invasive Versus Conventional Aortic Valve Replacement: A Propensity-Matched Study From the UK National Data.

OBJECTIVE: Minimally invasive aortic valve replacement (MIAVR) has been demonstrated as a safe and effective option but remains underused. We aimed to evaluate outcomes of isolated MIAVR compared with conventional aortic valve replacement (CAVR). METHODS: Data from The National Institute for Cardiovascular Outcomes Research (NICOR) were analyzed at seven volunteer centers (2006-2012). Primary outcomes were in-hospital mortality and midterm survival. Secondary outcomes were postoperative length of stay as well as cumulative bypass and cross-clamp times. Propensity modeling with matched cohort analysis was used. RESULTS: Of 307 consecutive MIAVR patients, 151 (49%) were performed during the last 2 years of study with a continued increase in numbers. The 307 MIAVR patients were matched on a 1:1 ratio. In the matched CAVR group, there was no statistically significant difference in in-hospital mortality [MIAVR, 4/307,(1.3%); 95% confidence interval (CI), 0.4%-3.4% vs CAVR, 6/307 (2.0%); 95% CI, 0.8%-4.3%; P = 0.752]. One-year survival rates in the MIAVR and CAVR groups were 94.4% and 94.6%, respectively. There was no statistically significant difference in midterm survival (P = 0.677; hazard ratio, 0.90; 95% CI, 0.56-1.46). Median postoperative length of stay was lower in the MIAVR patients by 1 day (P = 0.009). The mean cumulative bypass time (94.8 vs 91.3 minutes; P = 0.333) and cross-clamp time (74.6 vs 68.4 minutes; P = 0.006) were longer in the MIAVR group; however, this was significant only in the cross-clamp time comparison. CONCLUSIONS: Minimally invasive aortic valve replacement is a safe alternative to CAVR with respect to operative and 1-year mortality and is associated with a shorter postoperative stay. Further studies are required in high-risk (logistic EuroSCORE > 10) patients to define the role of MIAVR.

Anaphylaxis to muscle relaxants: an audit of ten years of allergy testing at the Royal Adelaide Hospital.

We audited patients with anaphylaxis to muscle relaxants during anaesthesia referred to the Department of Anaesthesia at the Royal Adelaide Hospital between the start of 2000 and the end of 2009. Of the 220 patients tested during this period, 43 had a positive intradermal test to the muscle relaxant given during their anaesthetic. The majority of these were to rocuronium and suxamethonium. Where rocuronium was the index agent, 65% of patients cross-reacted with another relaxant and 29% of patients with suxamethonium as their index agent demonstrated cross-reaction with another relaxant.

Speeding dantrolene preparation for treating malignant hyperthermia.

Dantrolene is known to have a low solubility in water Studies have demonstrated that it dissolves more rapidly in warm water However, the overall benefit of warming has not been measured. This study evaluated the overall time benefit of warming. The first step was to measure how long it took to warm the 10 ml plastic ampoules of sterile water from ambient temperature (20 degrees C) to 45 degrees C. We found that when immersed in a water bath held at 45 degrees C, this required a minimum of seven minutes. Therefore the ampoules used for the study were kept immersed in a water bath held at 45 degrees C for at least 10 minutes. It took an average of 82.6 seconds to draw 60 ml (six ampoules) of water into a 60 ml syringe. Squirting the water into the dantrolene vial and miring until dissolved took 102.8 seconds (SD 8.3) for the warmed water and 129.0 seconds (SD 14.6) for the ambient temperature water (P = 0.009). Redrawing the dantrolene solution into the syringe took an average of 32 seconds for the warmed water and 35.2 seconds for the ambient temperature water. After the redrawing phase the average temperature of the warmed solution was 32.2 degrees C. The average total preparation time for the warmed solution was 217.4 seconds (SD 20.0) and for the ambient temperature preparation was 243.0 seconds (SD 11.7) (P = 0.038). Thus the time difference in preparation was about 256 seconds, which is the time that could be saved in preparing the standard dose of 10 vials of dantrolene using water at 45 degrees C. However, as it required about seven minutes to initially warm the sterile ampoules, there would be a net increase, not decrease in the time required. These findings indicate that warming is of no benefit in speeding dantrolene preparation.

Celox (chitosan) for haemostasis in massive traumatic bleeding: experience in Afghanistan.

The use of Celox, a chitosan-based haemostatic agent, for the control of massive traumatic bleeding in patients arriving at a ROLE 2 (Enhanced Care) Facility in southwestern Afghanistan is described. Twenty-one soldiers with gunshot wounds were treated with successful haemostasis in 18 at the first application and in three after further applications. Celox is an effective haemostatic agent and a useful adjunct for the treatment of massive traumatic bleeding.

Omni-Stat (Chitosan) arrests bleeding in heparinised subjects in vivo: an experimental study in a model of major peripheral vascular injury.

OBJECTIVE: To explore the effectiveness of Omni-Stat (Chitosan) in a model of major haemorrhage in the presence of clotting dysfunction. METHOD: A total of 12 major femoral artery bleeds in moderately heparinised swine treated with Omni-Stat (Chitosan) were compared with five control bleeds. RESULTS: Haemostasis was successfully achieved at first treatment in 10 of 12 bleeds and at second treatment in the remaining two bleeds. CONCLUSION: The study supports the evidence that Omni-Stat (Chitosan) acts independently of classical clotting pathways and should be effective in patients with clotting dysfunctions, who suffer major haemorrhage. It also suggests the potential for a role in cardiac surgery.

Intermittent positive airway pressure to manage hypoxia during one-lung anaesthesia.

The effect of intermittent positive airway pressure to the non-ventilated lung was assessed in 10 patients who desaturated during one-lung ventilation. Once their saturation fell below 95% they were given a slow inflation of 2 l/min of oxygen into the non-ventilated lung for two seconds. This was repeated every 10 seconds for five minutes or until the saturation rose to 98%, whichever was sooner. The initial mean SpO2 was 89.3% +/- 4.2%. All 10 patients had an increase in saturation. The mean saturation following intermittent positive airway pressure was 96.5% +/- 1.6% (P < 0.0001). Similarly, the mean oxygen tension rose from 67.2 +/- 12.8 mmHg to 98.9 +/- 19.8 mmHg. Intermittent positive airway pressure should be considered for patients who desaturate while undergoing one-lung ventilation.

A new hemostatic agent: initial life-saving experience with Celox (chitosan) in cardiothoracic surgery.

Celox (MedTrade Products Ltd, Cheshire, UK) is a proprietary preparation of chitosan, indicated for moderate to severe hemorrhage and currently used for hemostasis in the emergency and military settings. We describe its lifesaving use in 2 patients undergoing cardiothoracic surgery in which conventional techniques had failed.

Modifiable risk factors remain significant causes of medium term mortality after first time Coronary artery bypass grafting.

BACKGROUND: Whilst there is much current data on early outcomes after Coronary artery bypass grafting(CABG), there is relatively little data on medium term outcomes in the current era. The purpose of this study is to present a single surgeon series comprising of all first time CABG patients operated on with the technique of cross clamp fibrillation from Feb-1996 to through to Jan-2003, and to seek risk factors for medium term mortality in these patients. METHODS: Data was collected from Hospital Episode Statistics and departmental patient administration and tracking systems and cross checked using database techniques. Patient outcomes were searched using the National Health Service strategic tracing service. RESULTS: Mean follow up was 5.3 years(0-9.4 years) and was complete for all patients. 30-day survival was 98.4%, 1-year survival 95% and 8-year survival 79%. Cox-regression analysis revealed that several modifiable pre-operative risk factors remain significant predictors of medium term mortality, including Diabetes(Hazard Ratio(HR) 1.73, 95%CI 1.21-2.45), Chromic obstructive pulmonary disease(HR 2.02, 95%CI 1.09-3.72), Peripheral vascular disease(HR 1.68, 95%CI 1.13-2.5), Body mass index>30(HR 1.54, 95%CI 1.08-2.20) and current smoker at operation(HR 1.67, 95%CI 1.03-2.72). However hypertension(HR 1.31, 95%CI 0.95-1.82) and Hypercholestrolaemia(HR 0.81, 95%CI 0.58-1.13) were not predictive which may reflect adequate post-operative control. CONCLUSION: Coronary artery bypass surgery using cross clamp fibrillation is associated with a very low operative mortality. Medium term survival is also good but risk factors such as smoking at operation, Chronic obstructive pulmonary disease, obesity and diabetes negatively impact this survival and should be aggressively treated in the years post-surgery.

Surgical resection of melorheostosis in the ribs.

Melorheostosis is a rare nongenetic developmental anomaly of the cortical bone. We present a 40-year-old woman who was diagnosed with melorheostosis affecting the ribs only. Chronic pain and cosmetic deformity were her presenting symptoms. She underwent posterolateral thoracotomy and excision of the affected ribs, with a satisfactory outcome of this uncommon presentation.

Pseudoanaphylaxis.

Profound hypotension and cardiac arrest after commencement of combined spinal and general anaesthesia in a patient for knee replacement surgery raised the suspicion of anaphylaxis. This seemed to be confirmed when a mast cell tryptase test taken about 90 minutes after the onset of the hypotension was elevated. However, subsequent intradermal skin testing twelve weeks later did not identify a causal drug. Repeat mast cell tryptase at the time showed the same elevation, which led to the correct diagnosis of mastocytosis and a secondary diagnosis that the patient's hypotension and cardiac arrest were the result of her spinal anaesthesia. If the serum tryptase is elevated during the event but no allergic agent can be identified, a further serum tryptase should be taken several weeks later to exclude a persistent elevation due to mastocytosis.

The margin of safety of a left double-lumen tracheobronchial tube depends on the length of the bronchial cuff and tip.

The left tracheobronchial double-lumen tube is the commonest device to separate the left and right lungs for differential ventilation. With the appropriate tube, the left bronchial cuff is positioned in the bronchus so that the cuff is beyond the carina but the tip of the tube does not occlude the aperture of the left upper lobe bronchus. The difference between the length of the left main bronchus and the length of the cuff and tip of the bronchial segment of the tube has been termed "the margin of safety" by Benumof. If the length of the cuff plus the tip exceeds that of the left main bronchus, there will be occlusion of the left upper lobe bronchus. The bronchial cuff and bronchial tip lengths were measured on two hundred and twenty left tracheobronchial (double-lumen) tubes from four manufacturers. The largest cuff-tip length was 40 mm with a Portex 41Fr tube but some 41Fr tubes from all manufacturers had cuff-tip lengths of 33 mm or greater which exceed the length of the shortest left main bronchus measured by Benumof. There was also a marked variation in cuff-tip lengths of the same size tube from the same manufacturer. The largest variation was 18 mm for the Portex 41 but substantial variation of 8 mm or more was found in at least one French size of all manufacturers. Users must be aware that significant cuff-tip length variation occurs and match the selected tube to the patient to ensure an adequate margin of safety.

The effects of ambient music on simulated anaesthesia monitoring.

We examined the effect of no music, classical music or rock music on simulated patient monitoring. Twenty-four non-anaesthetist participants with high or low levels of musical training were trained to monitor visual and auditory displays of patients' vital signs. In nine anaesthesia test scenarios, participants were asked every 50-70 s whether one of five vital signs was abnormal and the trend of its direction. Abnormality judgements were unaffected by music or musical training. Trend judgements were more accurate when music was playing (p = 0.0004). Musical participants reported trends more accurately (p = 0.004), and non-musical participants tended to benefit more from music than did the musical participants (p = 0.063). Music may provide a pitch and rhythm standard from which participants can judge changes in vital signs from auditory displays. Nonetheless, both groups reported that it was easier to monitor the patient with no music (p = 0.0001), and easier to rely upon the auditory displays with no music (p = 0.014).