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H L Du

Publications and source records attributed to H L Du.

10 recordsLinked to original sources
PubMed2006

Association of polymorphisms in the promoter region of chicken prolactin with egg production.

Chicken prolactin (PRL) is a physiological candidate gene for egg production. The objective of the current research was to investigate the association of polymorphisms in the chicken PRL promoter region with egg production. Genotyping of 177 individuals from White Leghorn, Yangshan, Taihe Silkies, White Rock, and Nongdahe breeds for 6 single nucleotide polymorphisms (C-2402T, C-2161G, T-2101G, C-2062G, T-2054A, and G-2040A) and 1 24-bp indel (insertion-deletion) at the site of -358 of the chicken PRL gene revealed large breed differences in allelic frequencies for all but the T-2101G and T-2054A polymorphisms. An F2 population produced from Nongdahe x Taihe Silkies chickens consisted of 374 hens, which were recorded for egg production traits and genotyped for the above 7 polymorphisms. Marker-trait association analysis indicated that the 24-bp indel was associated with egg production (P < 0.01) and that H3 (C C T C T G) was the most advantageous haplotype for egg production.

Alleles↗
PubMed2001

Automation of expiratory trigger sensitivity in pressure support ventilation.

Patients under pressure support ventilation sometimes encounter patient-ventilator asynchrony in the transition from inspiration to expiration, that is, expiratory asynchrony. This problem is caused by the incompatibility of the fixed level of expiratory trigger sensitivity termination criteria (i.e., flow termination criteria) in the ICU ventilators to various patient conditions. The user-adjustable expiratory trigger sensitivity implemented in some newly released ventilators has been experienced to be difficult to use and unable to adapt ever-changing patient conditions without user intervention, although it provides more flexibility. This article elucidates the rationale for automatic control of the expiratory trigger sensitivity and evaluates the automation system with a bench setup. The evaluation data suggest that good expiratory synchronies can be achieved through automatic adjustments of expiratory trigger sensitivity.

Humans↗
PubMed2001

Attenuation of haemodynamic responses to tracheal intubation by the styletscope.

Tracheal intubation often causes a haemodynamic response probably generated by direct laryngoscopy. The StyletScope is a new intubation device that does not require direct laryngoscopy. We prospectively measured haemodynamic changes after tracheal intubation using the StyletScope. The increase of heart rate was less during tracheal intubation with the StyletScope when compared with the Macintosh laryngoscope.

Adult↗
PubMed2000

Analysis of the mechanisms of expiratory asynchrony in pressure support ventilation: a mathematical approach.

A mathematical model was developed to analyze the mechanisms of expiratory asynchrony during pressure support ventilation (PSV). Solving the model revealed several results. 1) Ratio of the flow at the end of patient neural inspiration to peak inspiratory flow (VTI/V(peak)) during PSV is determined by the ratio of time constant of the respiratory system (tau) to patient neural inspiratory time (TI) and the ratio of the set pressure support (Pps) level to maximal inspiratory muscle pressure (Pmus max). 2) VTI/V(peak) is affected more by tau/TI than by Pps/Pmus max. VTI/V(peak) increases in a sigmoidal relationship to tau/TI. An increase in Pps/Pmus max slightly shifts the VTI/V(peak)-tau/TI curve to the right, i.e., VTI/V(peak) becomes lower as Pps/Pmus max increases at the same tau/TI. 3) Under the selected adult respiratory mechanics, VTI/V(peak) ranges from 1 to 85% and has an excellent linear correlation with tau/TI. 4) In mechanical ventilators, single fixed levels of the flow termination criterion will always have chances of both synchronized termination and asynchronized termination, depending on patient mechanics. An increase in tau/TI causes more delayed and less premature termination opportunities. An increase in Pps/Pmus max narrows the synchronized zone, making inspiratory termination predisposed to be in asynchrony. Increasing the expiratory trigger sensitivity of a ventilator shifts the synchronized zone to the right, causing less delayed and more premature termination. Automation of expiratory trigger sensitivity in future mechanical ventilators may also be possible. In conclusion, our model provides a useful tool to analyze the mechanisms of expiratory asynchrony in PSV.

Adult↗
PubMed1999

Efficiency of a new fiberoptic stylet scope in tracheal intubation.

BACKGROUND: Failed or difficult tracheal intubation is an important cause of morbidity and mortality during anesthesia. Although a number of fiberoptic devices are available to circumvent this problem, many do not allow manual control of the flexion of the tip and necessitate time-consuming preparation, special training, or the use of an external light source. To improve these limitations, the authors designed a new fiberoptic stylet scope (FSS) that has a simple form of a standard stylet with the fiberoptic view and maneuverability of its tip. This study was undertaken to prospectively evaluate the effectiveness of the FSS in tracheal intubation. METHODS: Thirty-two patients undergoing general surgery participated in this study. The authors used a standard laryngoscope only to elevate the tongue, then tracheal intubation was attempted with the glottic opening being viewed only through the FSS. The success rate, time necessary for intubation, hemodynamics, and adverse effects were recorded. RESULTS: The success rate of tracheal intubation on the first attempt using the FSS was 94% (30 of 32 patients), and the remaining two patients were intubated successfully on the second attempt. The mean time necessary for the intubation procedure was 29+/-14 s in all patients (mean +/- SD). Changes in hemodynamics during intubation were well within acceptable ranges. There were no major adverse effects, but minor sore throat (28%) and minor hoarseness (25%) on the first postoperative day. CONCLUSIONS: Tracheal intubation using the FSS proved to be a simple and effective technique for airway management.

Adult↗
PubMed1998

[Relationship between cardiac output and PETco2 as well as Paco2 during high-dose fentanyl anesthesia].

We investigated the relationship between cardiac output and PETCO2 as well as blood PCO2 in 10 patients undergoing cardiac surgery of long duration under high-dose fentanyl anesthesia. After anesthetic induction, the minute ventilation was kept constant at 10 ml.kg-1 x 10 cycles.min-1 and a pulmonary artery catheter was inserted. PETCO2, PaCO2 and cardiac index (CI) were measured simultaneously. PaCO2 was corrected for body temperature, and alveolar dead space-to-tidal volume ratio was calculated as VD/VTalv = (PaCO2-PETCO2)/PaCO2. After body, temperature became stabilized, the measurements were started and repeated every 10 to 20 minutes during the prebypass period. One hundred and eight sets of data were taken from 10 patients. PETCO2 correlated positively with CI. Similarly, PaCO2 correlated positively with CI, but VD/VTalv, did not correlate with CI. PETCO2 correlated closely and positively with PaCO2, but it correlated negatively and only marginally with VD/VTalv. When examined in individual patients, PaCO2 correlated positively with PETCO2 in all patients, while VD/VTalv correlated negatively with PETCO2 only in 3 patients. By multiple regression analysis, VD/VTalv change accounted for only 22.3 +/- 15.0% of PETCO2 change, while PACO2 or PaCO2 change accounted for 77.6 +/- 15.0% of PETCO2 change. Decreased CI was associated with decreased CO2 delivery from the tissue to the lung (DCO2) and PaCO2 decreased with decreasing DCO2. Decreased CI was also associated with decreased oxygen uptake (VO2), and PaCO2 decreased with decreasing VO2. A decrease in CI resulted in an increase in VA/Q, and PaCO2 decreased when VA/Q increased. PETCO2 decreased when cardiac output decreased. A decrease in PACO2 explained the decrease in PETCO2 better than an increase in VD/VT did. Decreased cardiac output might cause hypocapnia through decreased CO2 delivery to the lung, decreased CO2 production and/or increased ventilation-to-perfusion ratio.

Adult↗
PubMed1997

Vagal and sympathetic denervation in the development of oleic acid-induced pulmonary edema.

This study investigates the effects of autonomic denervation on extravascular lung water, pulmonary hemodynamics, the filtration coefficient of pulmonary vasculature and oxygenation in the development of pulmonary edema. Thirty seven dogs were divided into seven groups. No experimental treatment was conducted in group Nc (n = 4, sham operation) or group Nv (n = 6, bilateral vagotomy) during a 3 h observation period. In the following groups, oleic acid (0.06 ml/kg) was injected into a central vein to induce pulmonary edema: group OAc (n = 6, intact innervation); group OAv (n = 6, bilateral vagotomy); group OAa (n = 6, alpha-blockade by phentolamine); group OAs (n = 6, alpha- and beta-blockade by sympathectomy); and group OAvs (n = 3, vagosympathectomy). The results showed that in the dogs with normal lungs, bilateral vagotomy per se did not cause lung injury during 3 h of observation. However, in oleic acid pulmonary edema, vagotomy significantly deteriorated pulmonary edema by increasing pulmonary intravascular pressures; Alpha- or alpha- and beta- sympathetic inhibition deteriorated pulmonary edema by increasing pulmonary microvascular permeability. The severity of oleic acid-induced pulmonary edema was same in the dogs with vagosympathectomy as in the dogs with intact innervation. These results suggest the inhibition of vagal or sympathetic innervation will aggravate pulmonary edema in the dog.

Animals↗
PubMed1997

Beneficial effects of the prone position on the incidence of barotrauma in oleic acid-induced lung injury under continuous positive pressure ventilation.

BACKGROUND: Factors that contribute to ventilator-induced barotrauma are not well defined. This study investigates the effects of posture on ventilator-induced barotrauma, as well as arterial oxygenation. METHODS: Twelve dogs with oleic acid lung injury, lying in the prone position (n = 6) and right lateral position (n = 6), were mechanically ventilated with continuous positive pressure ventilation for 24 hours. The incidence of pneumothorax and arterial oxygenation were investigated in each position. RESULTS: All animals lying in the lateral position developed pneumothorax in the nondependent thorax, while only one animal in the prone position developed pneumothorax in the left thorax (P < 0.05). Postmortem examination revealed that in the lateral group, the nondependent lung consisted of large areas of emphysematous regions and neutrophil infiltration regions, while the dependent lung was composed of extensive atelectasis and neutrophil infiltration. Lung ruptures occurred in the nondependent lung at the regions of either emphysematous change or severe neutrophil infiltration. In the prone group, in contrast, both lungs were inflated fairly homogeneously with only small areas of atelectatic and emphysematous changes. In the dog in whom pneumothorax developed, lung ruptures were limited to the regions of severe neutrophil infiltration in the left lung. No animal in either group had a peak airway pressure more than 20 cmH2O. The peak airway pressures were 17.5 +/- 1.3 cmH2O in the lateral group and 16.6 +/- 2.1 cmH2O in the prone group (P > 0.05). Tidal volume was comparable between the lateral group (13 +/- 2 ml/kg) and the prone group (12 +/- 1 ml/kg) before pneumothorax occurred (P > 0.05). Arterial oxygenation was much better in the prone group than in the lateral group during the experiment (P < 0.05). CONCLUSION: It was concluded that in lung injury dogs, the prone position has beneficial effects on the incidence of ventilator-induced barotrauma and arterial oxygenation when compared with the lateral position. Ventilator-induced barotrauma may occur at lower airway pressure.

Animals↗