Impact of aerobic exercise capacity and procedure-related factors in lung cancer surgery.

Over the past decades, major progress in patient selection, surgical techniques and anaesthetic management have largely contributed to improved outcome in lung cancer surgery. The purpose of this study was to identify predictors of post-operative cardiopulmonary morbidity in patients with a forced expiratory volume in 1 s <80% predicted, who underwent cardiopulmonary exercise testing (CPET). In this observational study, 210 consecutive patients with lung cancer underwent CPET with completed data over a 9-yr period (2001-2009). Cardiopulmonary complications occurred in 46 (22%) patients, including four (1.9%) deaths. On logistic regression analysis, peak oxygen uptake (peak V'(O2) and anaesthesia duration were independent risk factors of both cardiovascular and pulmonary complications; age and the extent of lung resection were additional predictors of cardiovascular complications, whereas tidal volume during one-lung ventilation was a predictor of pulmonary complications. Compared with patients with peak V'(O2) >17 mL·kg⁻¹·min⁻¹, those with a peak V'(O2) <10 mL·kg⁻¹·min⁻¹ had a four-fold higher incidence of cardiac and pulmonary morbidity. Our data support the use of pre-operative CPET and the application of an intra-operative protective ventilation strategy. Further studies should evaluate whether pre-operative physical training can improve post-operative outcome.

Titrated sedation with propofol or midazolam for flexible bronchoscopy: a randomised trial.

In this study, we questioned whether propofol provided clinical benefits compared with midazolam in terms of neuropsychometric recovery, safety profile and patient tolerance. Patients, aged >18 yrs, were randomised to receive midazolam or propofol, given by non-anaesthetist physicians to achieve moderate levels of sedation as assessed by the electroencephalographic bispectral index (BIS; between 70 and 85). The primary end-point was the time delay until recovery of the BIS above 90. Other end-points included a neuropsychometric continuous performance test (CPT), serious respiratory adverse events, patient tolerance and physician satisfaction. Neuropsychometric recovery was improved in the propofol compared to the midazolam group as evidenced by faster normalisation of BIS index (5.4+/-4.7 min versus 11.7+/-10.2 min; p = 0.001) and better results at the CPT. In the midazolam group, 15% of patients presented profound sedation precluding CPT completion and one patient required mechanical ventilatory support. Patient tolerance was significantly better in the propofol group, whereas the operator's assessment was comparable in both groups. Compared with midazolam, propofol provided a higher quality of sedation in terms of neuropsychometric recovery and patient tolerance. BIS-guided propofol administration represents a safe sedation technique that can be performed by the non-anaesthesiologist.

Effects of methylene blue on propofol requirement during anaesthesia induction and surgery.

Delayed emergence from anaesthesia and neurological disturbances have been reported in patients undergoing parathyroidectomy who received methylene blue (MB) pre-operatively. We hypothesised that MB would decrease propofol requirements. The Bispectral index (BIS) and a target-controlled infusion of propofol were used in two groups of 11 matched patients. Patients in one group were pretreated with MB. During induction, clinical sedation scores and BIS values were significantly lower at the predicted effect-site propofol concentration of 2 microg x ml(-1) in the MB compared with the control group. Intra-operatively, although similar BIS values were achieved in the two groups, patients pretreated with MB required a mean 50% lower dose of propofol compared with controls. In view of these findings, care should be taken to ensure an adequate depth of anaesthesia by titrating the administration of anaesthetic agents whenever MB is infused peri-operatively.

Cardiovascular response to acute normovolaemic haemodilution in patients with severe aortic stenosis: assessment with transoesophageal echocardiography.

Using multiplane transoesophageal echocardiography (TOE), we investigated the haemodynamic response to acute normovolaemic haemodilution (ANH) in anaesthetised patients with critical aortic stenosis. Twenty-eight patients were randomly assigned to ANH or control groups. In the control group, haemodynamic data remained unchanged over a 20-min period. In the ANH group, haemoglobin levels decreased from a mean (SD) of 134 (7) to 91 (9) g x l(-1) (p < 0.001) whereas stroke volume, central venous pressure and left ventricular (LV) end-diastolic area all increased significantly (mean (SD) +15 (6) ml; +2.0 (1.1) mmHg; +2.1 (0.8) cm2, respectively). During ANH, the accelerated blood flow through the stenotic valve caused an increased loss (SD) in LV stroke work: from 24 (8)% to 30 (10)%), (p < 0.01). Hence, lowering viscosity with ANH resulted in improved venous return, higher cardiac preload and increased stroke volume. However, this adaptive haemodynamic response was limited by less efficient LV stroke work due to dissipation of fluid kinetic energy.

Continuous haemodynamic monitoring using transoesophageal Doppler during acute normovolaemic haemodilution in patients with coronary artery disease.

Transoesophageal Doppler monitoring allows non-invasive assessment of stroke volume. We studied haemodynamic changes during acute normovolemic haemodilution (ANH) in anaesthetised patients with coronary artery disease. Twenty patients were randomly assigned to either ANH or a control group. During ANH, a mean (SD) blood volume of 15.3 (3.4) ml.kg(-1) was withdrawn decreasing systemic oxygen delivery from 12.7 (3.3) to 9.3 (1.8) ml.kg(-1).min(-1) (p < 0.001). In the control group, haemodynamic data remained unchanged, whereas in the ANH group, stroke volume and central venous pressure increased significantly (mean = +21 ml [95% CI: 18-25 ml.min(-1)]; mean = +2.5 mmHg [95% CI: 2.2-2.8 mmHg], respectively) and heart rate decreased (mean = -6 beat.min(-1)[95% CI: 6-8 beat.min(-1)], p < 0.05). According to the Frank-Starling relationship, individual changes in stroke volume compared with central venous pressure fitted a quadratic regression model (R2 > 0.91). A reduced viscosity associated with ANH resulted in improved venous return, higher cardiac preload and increased cardiac output. In summary, this study demonstrated that ANH to a haemoglobin value of 8.6 g.dl(-1) was well tolerated in patients with coronary artery disease.

Direct measurements of natural planktonic bacterial community viability by flow cytometry.

A range of fluorescent viability dyes were used in conjunction with flow cytometry to rapidly enumerate viable bacteria from freshwater environments. Optimal labelling was achieved by using carboxyfluorescein diacetate or chemchrome B with a detergent-mediated permeabilization step. The viable bacterial count under optimal conditions was 7% in oligotrophic lake water and 75% in polluted river water.

Survival of Staphylococcus aureus in lakewater monitored by flow cytometry.

The ability of flow cytometry to detect and enumerate viable bacteria during survival in a lakewater microcosm was assessed using Staphylococcus aureus as a model organism. Counts of colony-forming units (c.f.u.) on nutrient agar were not significantly different from those obtained by flow cytometric detection of rhodamine 123 stained bacteria and there was no evidence for a viable but nonculturable state using these methods. However c.f.u. were significantly lower when estimated using mannitol salts agar compared with nutrient agar. S. aureus was also enumerated immunofluorescently after staining with FITC-IgG. There was no significant difference between the population estimated immunofluorescently and by acridine orange direct counting, and unlike estimations of viability, only slight reductions in total cell numbers were observed. Changes in the protein and nucleic acid content of S. aureus during survival were also measured by flow cytometry to investigate any potential heterogeneity arising within the starved population. Flow cytometric determinations were found to correlate significantly with their respective chemical determinations. These results demonstrate the ability of flow cytometry to detect viable bacteria during starvation and to study changes in macromolecular content. They also illustrate the importance of using appropriate methods for the detection of viable bacteria in environmental samples.

Rapid assessment of bacterial viability by flow cytometry.

The ability of a flow cytometer to rapidly assess microbial viability was investigated using three vital stains: rhodamine 123 (Rh123); 3,3'-dihexyloxacarbocyanine iodide [DiOC6(3)] and fluorescein diacetate (FDA). Rh123 was found to clearly differentiate viable from non-viable bacteria. The methodology for staining bacteria with this dye was optimised. Rh123 was shown to stain and discriminate several different species of viable bacteria although this was not universal. Viable cells of Bacillus subtilis were found to stain better with FDA than with Rh123. The results demonstrate the ability of flow cytometry to rapidly detect and estimate the viability of bacterial populations.

Nitrate content of vegetables commercially grown on land subject to inorganic or organic fertiliser.

A relatively quick and simple spectrophotometric method of measuring nitrate concentrations in vegetables has been used incorporating a Cu-Zn couple to provide a nitrate-free reference sample. This technique has been used in a preliminary study of the nitrate content of carrots and cabbages commercially grown on soils treated with either inorganic or organic fertiliser and available through normal retail outlets. Although it cannot be concluded that the nitrate levels in the organically fertilised vegetables were lower than those grown using conventional inorganic fertiliser, it can be concluded that the precise conditions of cultivation and soil do affect the nitrate levels in carrots and cabbages grown commercially.