A prototype small-bore ventilation catheter with a cuff: cuff inflation optimizes ventilation with the Ventrain.

BACKGROUND: Ventilation through small-diameter tubes typically precludes use of a cuff as this will impede the necessary passive outflow of gas alongside the tube's outer surface. Ventrain assists expiration and enables oxygenation and normoventilation through small-bore cannulas or catheters, particularly in obstructed airways. A small-bore ventilation catheter (SBVC; 40 cm long, 2.2 mm inner diameter) with a separate pressure monitoring lumen and a cuff was developed. Efficacy of oxygenation and ventilation with Ventrain through this catheter was investigated in sealed and open airways in a porcine cross-over study. METHODS: Six pigs were ventilated with Ventrain (15 l/min oxygen, frequency 30 breaths per min, I : E-ratio 1 : 1) through the SBVC, both with the cuff inflated and deflated. Prior to each test they were ventilated conventionally until steady state was achieved. RESULTS: With an inflated cuff, PaO2 rose instantly and remained elevated (median [range] PaO2 61 [52-69] kPa after 30 min; P = 0.027 compared to baseline). PaCO2 remained stable at 4.9 [4.2-6.2] kPa. After cuff deflation, PaO2 was significantly lower (9 [5-28] kPa at 10 min, P = 0.028) and interventional ventilation had to be stopped prematurely in five pigs as PaCO2 exceeded 10.6 kPa. Pulmonary artery pressures increased markedly in these pigs. Intratracheal pressures were kept between 5 and 20 cmH2 O with the cuff inflated, but never exceeded 2 cmH2 O after cuff deflation. CONCLUSION: The SBVC combines the benefits of a small diameter airway and a cuff. Cuff inflation optimizes oxygenation and ventilation with Ventrain.

Accuracy, Precision, and Trending Ability of Electrical Cardiometry Cardiac Index versus Continuous Pulmonary Artery Thermodilution Method: A Prospective, Observational Study.

INTRODUCTION: Evaluation of accuracy, precision, and trending ability of cardiac index (CI) measurements using the Aesculon™ bioimpedance electrical cardiometry (Aesc) compared to the continuous pulmonary artery thermodilution catheter (PAC) technique before, during, and after cardiac surgery. METHODS: A prospective observational study with fifty patients with ASA 3-4. At six time points (T), measurements of CI simultaneously by continuous cardiac output pulmonary thermodilution and thoracic bioimpedance and standard hemodynamics were performed. Analysis was performed using Bland-Altman, four-quadrant plot, and polar plot methodology. RESULTS: CI obtained with pulmonary artery thermodilution and thoracic bioimpedance ranged from 1.00 to 6.75 L min-1 and 0.93 to 7.25 L min-1, respectively. Bland-Altman analysis showed a bias between CIBIO and CIPAC of 0.52 liters min-1 m-2, with LOA of [-2.2; 1.1] liters min-1 m-2. Percentage error between the two techniques was above 30% at every time point. Polar plot methodology and 4-quadrant analysis showed poor trending ability. Skin incision had no effect on the results. CONCLUSION: CI obtained by continuous PAC and CI obtained by Aesculon bioimpedance are not interchangeable in cardiac surgical patients. No effects of skin incision were found. International clinical trial registration number is ISRCTN26732484.

Retrograde autologous priming reduces transfusion requirements in coronary artery bypass surgery.

The hypothesis was tested whether retrograde autologous priming (RAP) of the cardiopulmonary bypass system, compared to a standard primed system (NON-RAP group), results in less haemodilution and less transfusion of packed red blood cells. Retrospectively, data was collected from the medical charts of one hundred patients undergoing elective coronary artery bypass grafting using cardiopulmonary bypass. Fifty patients where RAP was used have been compared to fifty patients using NON-RAP. The prime volume in the NON-RAP group was 1,627±108 mL versus 782±96 mL in the RAP group (p<0.001). The lowest haematocrit during perfusion was 22% in the NON-RAP group versus 26% when the RAP technique was used (p<0.001). In the NON-RAP group, 26% of the patients received packed red cells in contrast to 6% in the RAP group (p<0.012). A positive association was found between RAP and less transfusion of packed red blood cells (p<0.012). In conclusion, retrograde autologous priming, reducing the prime volume of the cardiopulmonary bypass system, causes less haemodilution and reduces intraoperative transfusion of packed red blood cells.

Predictors of cardiac responsiveness to fluid therapy after cardiac surgery.

OBJECTIVES: Central venous pressure (CVP) and pulmonary capillary wedge pressure (PCWP) are insensitive preload markers and sometimes misleading. The introduction of the pulse contour method for monitoring of continuous cardiac output enabled the real-time quantification of stroke volume variation (SVV). Studies evaluating the accuracy of this parameter as a measure of preload responsiveness are still limited and conflicting results have been published in cardiac surgical patients. The aim of this study was to reevaluate the predictive value of SVV regarding cardiac responsiveness to fluid therapy and to compare it with the standard preload variables in a clinical setting in the ICU after cardiac surgery. METHODS: The assessment of cardiac responsiveness to fluid therapy (HAES-steril 6% 10 mL * Body Mass Index) was performed in 92 ventilated coronary artery surgical patients after arrival in the ICU. After the fluid load, detailed hemodynamic measurements were performed. A 'responder' was defined as a patient with a gain in stroke volume index (SVI) of 5% or more from baseline value to the volume challenge. RESULTS: Post hoc analysis showed that there were 47 responders to the fluid challenge and 45 non-responders. Hemodynamic data before the fluid therapy show that stroke volume variation in the responders group was significantly higher than in the non-responders groups (9.7 +/- 4.3% versus 7.6 +/- 3.0%, P = 0.01). The receiver operating characteristic curves for the baseline values of CVP, PCWP and SVV were constructed for illustrative purposes. The area under the curve for baseline values of SVV was significantly higher than random guess (area = 0.65, p < 0.05), indicative for the value of SVV as a marker of cardiac responsiveness to fluid therapy. The static preload parameters CVP and PCWP had no predictive value. CONCLUSION: SVV as measured with the LiDCO system is a better functional marker of cardiac responsiveness to fluid therapy than the static parameters CVP and PCWP.

Evaluation of two different epidural catheters in clinical practice. narrowing down the incidence of paresthesia!

Although epidural anesthesia is considered safe, several complications may occur during puncture and insertion of a catheter. Incidences of paresthesia vary between 0.2 and 56%. A prospective, open, cohort-controlled pilot study was conducted in 188 patients, ASA I-III, age 19-87 years, scheduled for elective surgery and epidural anesthesia. We evaluated a 20 G polyamide (standard) catheter and a 20 G combined polyurethane-polyamide (new) catheter. Spontaneous reactions upon catheter-insertion, paresthesia on questioning, inadvertent dural or intravascular puncture, and reasons for early catheter removal were recorded. The incidence of paresthesia reported spontaneously was 21.3% with the standard catheter and 16.7% with the new catheter. Systematically asking for paresthesia almost doubled the paraesthesia rate. Intravascular cannulation occurred in 5%. No accidental dural punctures occurred. An overall incidence of 13.3% of technical problems led to early catheter removal. The new catheter was at least equivalent to the standard regarding epidural success rate and safety : rate of paresthesia, intravascular and dural cannulation.

Prevalence of visual and hearing impairment in a Dutch institutionalized population with intellectual disability.

A screening of hearing and visual function was performed using clinical assessment methods in a Dutch institutionalized population of 672 people with mild to profound intellectual disability (ID). Because the studied population was not comparable to the total Dutch population with ID, subgroups were distinguished according to level of ID, age younger and older than 50 years, and the presence or absence of Down's syndrome (DS). The prevalences of both hearing and visual impairment were considerably increased in all subgroups, as compared with the general population. In the least affected group, i.e. those < 50 years with a mild or moderate ID by other causes than DS, the prevalences of hearing and visual impairment were 21% and 4%, respectively (as opposed to 2-7% and 0.2-1.9% in the general Dutch population <50 years, respectively). The prevalence of hearing impairment showed a sharp and highly significant increase in individuals with DS and subjects > or = 50 years. To a lesser extent, young adults with severe or profound ID had an increased risk of hearing impairment. Visual impairment and blindness were specifically highly prevalent in people with severe or profound ID (51% < 50 years of age). Down's syndrome and an age > or = 50 years were also significant risk factors for visual impairment. There was an alarmingly high prevalence of combined sensory impairment, especially in those with severe or profound ID (20%). Although hearing impairment had been diagnosed prior to this screen in 138 people and visual impairment in 65 individuals, a first diagnosis of hearing impairment was made in 128 subjects and of visual impairment in 90 cases. This highlights the tendency for sensory impairments to go unnoticed in people with ID, which is not restricted to those with severe or profound ID. Therefore, the present authors stress the importance of regular screening as outlined in the existing IASSID international consensus statement.

Method of stimulation, mouth movements, concentration, and viscosity: effects on the degree of taste adaptation.

Although sensory adaptation, the gradual loss of sensation during prolonged stimulation, has been demonstrated in laboratory taste experiments, a comparable loss of taste intensity is not experienced in real-life eating situations. This discrepancy may be due to differences in the proximal stimuli or to differences in the ways the taste receptors are stimulated. In two experiments, the effects of four potentially relevant variables were investigated: stimulus intensity, stimulus viscosity, mouth movements, and presentation method. During the initial seconds of stimulation, adaptation to the weakest of the two solutions was faster. Although more viscous stimuli were less sweet, viscosity as such did not affect adaptation rate, nor did mouth movements. Among the three presentation methods, a sucrose-soaked filter paper on the tongue produced more adaptation than either sipping the solution or flowing it over the tongue. This suggests that even mouth movements far more subtle than those still present in the no-movement condition of a sip-and-spit experiment can disrupt the adaptation process.

Taste adaptation during the eating of sweetened yogurt.

Taste adaptation, a gradual decline of taste intensity with prolonged stimulation, is frequently observed in laboratory experiments. However, during normal eating the taste of food does not seem to decrease or disappear. During eating, the presence of saliva, the interactions between tastants and odorants, and mouth movements can influence the time course of taste intensity. Therefore, results from standard laboratory adaptation experiments about adaptation seem of limited relevance to the prediction of the time course of taste intensity when eating real foods. We studied whether taste adaptation occurs when subjects eat yogurt, sweetened with two concentrations of sucrose (3.75 and 7.5%). In addition, we examined whether this adaptation is related to taste adaptation measured with a filter paper method. During the eating of yogurt, sweetness intensity declined with time, whereas sourness intensity did not. As expected, taste adaptation in the "yogurt task" was only slightly correlated to adaptation measured with filter paper.

Mouth movements diminish taste adaptation, but rate of mouth movement does not affect adaptation.

The degree of adaptation to five concentrations of sucrose was measured. Solutions were kept in the mouth for 25 s; a sweetness judgement was given every 5 s. There were four conditions of mouth movements: no movement, slow, medium and fast mouth movements. It was found that when mouth movements are made there is less adaptation than when there is no mouth movement; however, the rate of movement does not appear to influence the degree of adaptation. Furthermore concentration was found to have an effect. In the no-movement condition, the degree of adaptation seems to rise with concentration, whereas in the movement conditions the opposite effect occurs, i.e. a decrease in the degree of adaptation occurs with increasing sucrose concentration. These phenomena might be explained by the stimulated tongue area, or by taste constancy.

Recalling taste intensities in sweetened and salted liquids.

The effect of training on recalling taste intensities over 6 weeks was studied using an ad libitum mixing procedure. Subjects tasted sweet and salty standards labeled as "weak' and "strong' (3 and 8% sucrose in redcurrant juice; 0.4 and 1.2% NaCl in beef broth). They subsequently mixed unsweetened and sweetened juice, and unsalted and salted broth, to produce taste intensities that corresponded to the standards. A minimum training (MT) group (n = 13) produced comparison stimuli by tasting and directly comparing with standards in one session only; an extensive training (ET) group (n = 13) did this in six sessions before producing comparison stimuli based on memory only at 1 h, 1 day, 1 week and 6 weeks. An upward bias (chemically determined concentrations of comparison stimuli exceeding those of standards) occurred at 1 day or 1 week in MT subjects for 'weak' and 'strong' sweetness, and for 'strong' saltiness, and sustained thereafter. The upward tendency was also observed in ET subjects but was significant only for 'strong' sweetness. It is important to recognize memory effects such as the one described, as they affect food perceptions and can be a major source of bias in sensory food research.

The effect of sweeteners on perceived viscosity.

Two different sweeteners, sucrose and aspartame, were matched in perceived sweetness intensity. These solutions were thickened with carboxymethylcellulose to six different viscosity levels. Sucrose and aspartame appeared to decrease perceived viscosity of the solutions at a specific sweetener concentration, at all viscosity levels. However, in a second similar experiment with three viscosity levels and seven sucrose concentrations no effect of sucrose concentration on perceived viscosity was found. Reasons for these conflicting results are discussed. No definite conclusions about the effect of sweeteners on perceived viscosity can as yet be drawn.

Umbilical artery blood velocimetry: a prospective longitudinal study in search of the intrauterine growth-retarded fetus.

In a longitudinal prospective study involving 125 patients, blood velocity waveforms in the umbilical artery were recorded and analyzed from the 15th week of gestation until term to evaluate the predictive value of blood velocity parameters with regard to fetal growth retardation. Measurements were performed with a combined real-time linear array and 2-MHz pulsed Doppler technique. The mean values (+/- 2 S.D.) of the A/B ratio, resistance index (RI) and pulsatility index (PI) were calculated from the 15th to the 40th week of gestation. The degree of intrauterine growth retardation was related to postnatal catch-up growth. Three groups of patients were compared with regard to blood velocity waveform indices. Group NL-I/II: waveform indices (WI) within 2 S.D. of the population mean. Group EL-II: consistently WIs above 2 S.D. of the population mean. Significant differences with regard to neonatal growth variables were found between these groups. In spite of the fact that these differences in growth variables were statistically significant, no clear relationship was found between the velocity waveform indices and true intrauterine growth retardation, defined by a non-birthweight criterion. It seems that umbilical artery velocimetry cannot predict true intrauterine growth retardation.