Coaching Reduced the Radiation Dose of Pain Physicians by Half during Interventional Procedures.

The increased use of C-arm fluoroscopy in interventional pain management has led to higher radiation exposure for pain physicians. This study investigated whether or not real-time radiation dose feedback with coaching can reduce the scatter dose received by pain physicians. Firstly, phantom measurements were made to create a scatter dose profile, which visualizes the average scatter radiation for different C-arm positions at 3 levels of height. Secondly, in the clinical part, the radiation dose received by pain physicians during pain treatment procedures was measured real-time to evaluate (1) the effect of real-time dose feedback on the received scatter dose, and (2) the effect of knowledge of the scatter dose profile and active coaching, on the scatter dose received by the pain physician. The clinical study included 330 interventional pain procedures. The results showed that real-time feedback of the received dose did not lead to a reduction in scatter radiation. However, visualization of the scatter dose in a scatter dose profile and active coaching on optimal positions did reduce the scatter radiation received by pain physicians during interventional pain procedures by 46.4% (P = 0.05). Knowledge of and real-time coaching with the scatter dose profile reduced the dose of pain physicians by half, caused by their increased awareness for scatter radiation and their insight into strategic positioning.

Xenon anaesthesia for laparoscopic cholecystectomy in a patient with Eisenmenger's syndrome.

There are few reports on anaesthesia for patients with Eisenmenger's syndrome requiring non-cardiac surgery and none of the use of xenon. We describe the use of xenon with a closed-circuit system in a patient with Eisenmenger's syndrome having a laparoscopic cholecystectomy.

A novel method of evaluation of three heat-moisture exchangers in six different ventilator settings.

OBJECTIVE: The purpose of this study was to assess and compare the humidification, heating, and resistance properties of three commercially available heat-moisture exchangers (HMEs). To mimic clinical conditions, a previously validated, new, realistic experimental set-up and measurement protocol was used. DESIGN: Prospective, comparative experimental study. SETTING: Surgical Intensive Care Unit, University Hospital of Rotterdam. MATERIALS: An experimental set-up consisting of a patient model, measurement systems, and ventilator and three different HME types. INTERVENTIONS: The air flow, pressure in the ventilation circuit, pressure difference over the HME, and partial water vapour pressure and temperature at each side of the HMEs were measured. Measurements were repeated every 30 min during the first 2 h and every hour up to 24 h for each HME at six different ventilator settings. The mean inspiratory and maximum expiratory resistance, flow-weighted mean absolute humidity and temperature outputs, and humidification and heating efficiencies of HMEs were calculated. MEASUREMENTS AND RESULTS: The Dar Hygroster had the highest humidity output, temperature output, humidification efficiency, and heating efficiency values throughout the study (32.8 +/- 21. mg/l, 32.2 +/- 0.8 degrees C, 86.3 +/- 2.3%, and 0.9 +/- 0.01%, respectively) in comparison to the Humid-Vent Filter (25.3 +/- 3.2 mg/l, 31.9 +/- 0.8 degrees C, 72.2 +/- 5.3%, 0.9 +/- 0.02%, respectively) and the Pall Ultipor BB100 breathing circuit filter (23.4 +/- 3 mg/l, 28.3 +/- 0.7 degrees C, 68.8 +/- 5.9%, 0.8 +/- 0.02%, respectively). The inspiratory and expiratory resistance of the HMEs remained below clinically acceptable maximum values (2.60 +/- 0.04 and 2.45 +/- 0.05 cmH2O/l per s, respectively). CONCLUSION: The Dar Hygroster filter was found to have the highest humidity and temperature output of all three HMEs, the Humid-Vent filter had a satisfactory humidity output only at low tidal volume flow rate and minute volume settings, whereas the Pall Ultipore BB 100 never achieved a sufficient humidity and temperature output.

Clinical evaluation of diminished early expiratory flow (DEEF) ventilation in mechanically ventilated COPD patients.

OBJECTIVE: To evaluate the cardiopulmonary effects, especially the end-expiratory lung volume (EEV) and ventilation inhomogeneity during diminished early expiratory flow ventilation (DEEF), which resembles pursed-lips breathing, with the conventional intermittent positive pressure ventilation (IPPV) in postoperative mechanically ventilated patients with chronic obstructive pulmonary disease (COPD). DESIGN: A prospective study measuring cardiopulmonary parameters during IPPV, DEEF, and positive end-expiratory pressure (PEEP) as a control mode. In the PEEP mode, PEEP values were chosen such that the mean airway pressure during a breath cycle was equal to that during the DEEF mode, which was higher than the conventional IPPV mode. SETTING: Surgical intensive care unit of a university hospital. PATIENTS: 20 postoperative mechanically ventilated COPD patients who were optimally pretreated and had normal blood oxygenation. INTERVENTIONS: Measurements were started in the IPPV (IPPV1) mode, continued in a randomized order with DEEF or PEEP, and completed with a second IPPV (IPPV2) mode, with 1 h equilibration time in each mode before each measurement. MEASUREMENTS AND RESULTS: A multi-breath indicator gas wash-out test was used to calculate the EEV and ventilation inhomogeneity. There was a 9% increase (p < 0.05) in the mean EEV during both the DEEF and PEEP mode compared to IPPV. No significant changes in the ventilation inhomogeneity and deadspace fractions or the hemodynamic parameters were found during the different ventilatory modes. CONCLUSIONS: There was no improvement in pulmonary and hemodynamic parameters during the DEEF mode in comparison to the IPPV mode. The small increase in EEV during DEEF was probably caused by the slightly higher mean expiratory pressures as in the PEEP mode. However, this had no effect on the hemodynamic parameters. As we could not observe any improvement with the DEEF ventilation in our optimally pretreated postoperative COPD patients, we do not advise applying this therapy in this group of patients, since this mode of ventilation may cause barotrauma if not monitored adequately.

An experimental set-up to test heat-moisture exchangers.

OBJECTIVES: The purpose of this study was to build an experimental set-up to assess continuously the humidification, heating and resistance properties of heat-moisture exchangers (HMEs) under clinical conditions. DESIGN: The experimental set-up consists of a patient model, measurement systems and a ventilator. SETTING: Surgical ICU, University Hospital of Rotterdam. MATERIALS: A clinically used HME. MEASUREMENTS AND RESULTS: The air flow, pressure in the ventilation circuit, pressure difference over the HME, and partial water vapour pressure and temperature at each side of the HME were measured. The resistance, absolute humidity, humidification efficiency and temperature difference at the patient side of the HME were calculated. Measurements were performed during 24 h. The temperature output, humidity output and lung mechanics of the patient model were similar to values found in mechanically ventilated patients. The measurement system was in agreement with the ISO draft standard and was capable of measuring dynamic variation of water and heat exchange over the range of a clinically used ventilator setting. CONCLUSION: The experimental set-up described is reliable for evaluating HMEs and can also be used for future clinical evaluation of HMEs. The main advantages of this set-up over those described previously are: (i) measurements of dynamic variations of water and heat exchange; (ii) on-line measurements of expiratory, as well as inspiratory resistance.

A new ventilation inhomogeneity index from multiple breath indicator gas washout tests in mechanically ventilated patients.

OBJECTIVES: a) To determine the validity of a new method to analyze indicator gas washout tests on mechanically ventilated patients. This method takes into account the difference between the end-expiratory gas fraction and the mean gas fraction in the lung and provides the end-expiratory lung volume and a new index of ventilation inhomogeneity called volumes regression index. b) To determine the validity of this index as a predictor of chronic obstructive pulmonary disease. c) To compare this index with the moment ratio index and Becklake index. DESIGN: Prospective study of diagnostic test. Criterium standards: Closed-circuit indicator gas dilution technique and Tiffeneau index. SETTING: Surgical intensive care unit of a university hospital. PATIENTS: A total of 38 mechanically ventilated postoperative patients, divided into two groups: the obstructive group (n = 21) and the nonobstructive group (n = 17), based on their preoperative lung function. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: a) The mean coefficient of variation of all lung volume measurements in a group of nine healthy volunteers was 5%, and the difference between this technique and the closed-circuit helium dilution measurements was -2 +/- 5%. In patients, the mean coefficient of variation of the lung volume measurements was 3.5%. The volumes regression index was measured as 0.02 +/- 0.04 in a dummy lung, 0.37 +/- 0.08 in the healthy volunteers, 0.64 +/- 0.23 in the nonobstructive patients, and 1.1 +/- 0.3 in the obstructive patients. The volumes regression index provided a better correlation (r2 = .46) with preoperatively determined Tiffeneau index than the Becklake index (r2 = .11) or the moment ratio index (r2 = .18). CONCLUSION: The proposed technique provides a means for accurate measurement of the end-expiratory lung volume and the amount of ventilation inhomogeneity in mechanically ventilated intensive care unit patients.

Differences between arterial and venous occlusion in microvascular surgery.

Between November 1985 and November 1988 11 patients developed arterial occlusion after microvascular anastomoses, 10 patients venous occlusions and five combined arterial and venous occlusions. We undertook a retrospective study to see whether colour, capillary refill, thermometry, or laser Doppler measurements could distinguish arterial and venous occlusions. Neither skin thermometry nor total backscattered light intensity change and flow band width (laser Doppler measurements) were significantly different (p > 0.05) between arterial and venous occlusions, but there were significant differences in colour (p = 0.006), capillary refill (p = 0.007), and laser Doppler flow (p = 0.02). The values obtained from cases with combined arterial and venous occlusions were like those of a venous occlusion or of an arterial occlusion or somewhere in between. Although none of the variables was diagnostic, we advise that the suspect vascular anastomosis should first be checked during reoperation. If an occluded anastomosis is found, one should also check the other anastomosis because occlusion of both artery and vein cannot be reliably detected.

A simple device to inject indicator gas for wash-out tests during mechanical ventilation.

OBJECTIVE: To evaluate a simple device which injects a constant fraction of indicator gas to the inspiratory mixture for performing multi-breath wash-out tests during controlled ventilation. DESIGN: the technique in which the indicator gas is injected at the mouth of the patient (post-mix) is compared with the technique where the indicator gas is administered in the bellows of the ventilator (pre-mix). SETTING: Surgical Intensive Care Unit of a University Hospital. PATIENTS: 10 post-operative mechanically ventilated patients. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: 3 wash-out tests with the post-mix and 3 wash-out tests with the pre-mix method were performed within an hour on every patient. The calculated mean end expiratory lung volume (EEV) was 1.91 +/- 0.871 with the post-mix technique and 1.89 +/- 0.881 with the pre-mix technique. There was a good agreement with a mean difference of -1.9 +/- 6.5% in the calculated EEV values by the two different techniques. CONCLUSION: The described injector is an affordable device, is easy to assemble and can be incorporated in most electronically regulated ventilators to perform multi-breath indicator gas wash-out tests for pulmonary monitoring at the bed side of ICU patients.