Gallbladder size: is it affected by the oral intake of water or dilute contrast medium?

Examinations of the gallbladder are performed by ultrasonography while patients are in a fasting state. In contrast, computed tomography of the abdomen is carried out in fasting patients who were given 2% meglumine diatrizoate (Urografin) solution to opacify the gut. Sonographic examination was performed to establish whether the weight of fluids given to patients had any effect on the volume of the gallbladder. Gallbladder size was measured in subjects with a normal gallbladder. The gallbladder also was measured in 117 people in the fasting state, and 10 and 30 minutes later, it was measured again after an intake of 500 ml of water or a dilute solution of contrast medium. Both groups showed evidence of gallbladder contraction, but no significant statistical difference between them was apparent. It appears, therefore, that the contrast medium solution given before abdominal computed tomography may cause some gallbladder contraction.     

Is Same‐Day Sonography of the Gallbladder Feasible After Intravenous Urography or Contrast‐Enhanced Computed Tomography?

OBJECTIVE: To determine whether same-day sonographic evaluation of the gallbladder is possible after the use of oral or intravenous iodinated contrast agents during intravenous urography or computed tomography. METHODS: One hundred fifty-three patients involved in this prospective study received low-osmolar or conventional contrast material. Each preparation contained 300 mg/mL iodine. Sixty-six patients received contrast agents intravenously, and 87 received them orally. Gallbladder volume was estimated sonographically, and the precontrast volume was used to calculate the volume after contraction at 30-minute intervals up to 2 hours after contrast agent administration. RESULTS: Gallbladder volume returned to precontrast values at 2 hours irrespective of the type of contrast agent or route of administration. The mean volume after contraction at 0.5 hour was 71% after intravenous contrast agent administration and 76% after oral contrast agent administration. Both changes were statistically significantly different from precontrast values (P < .01, null hypothesis) and were unaffected by the osmolarity of the contrast agent. CONCLUSIONS: Gallbladder volume was restored to precontrast values 2 hours after contrast agent administration. Thus any strategy involving simultaneous same-day sonographic or computed tomographic assessment of the gallbladder after contrast agent administration can be confidently undertaken after this period. This finding may have cost-saving implications.     

Three-dimensional sonographic evaluation of gallbladder contractility: comparison with cholescintigraphy

PURPOSE: To compare three-dimensional sonography (3D US) with quantitative cholescintigraphy for assessing gallbladder contractility. METHODS: Gallbladder radioactivity was assessed in 35 patients with suspected gallbladder disease using a gamma camera 5, 30, 60, and 90 minutes after technetium 99m (Tc-99m) DISIDA injection and 30 and 60 minutes after ingestion of a high-fat meal. Immediate gallbladder images were obtained via 3D US. Gallbladder radioactivity at 120 minutes after injection of Tc-99m DISIDA was defined as 100%, and gallbladder contractility was calculated. Gallbladder volume on 3D US was calculated using a dedicated software. Pearson correlation analysis and simple linear regression analysis were used. RESULTS: The mean gallbladder volume on 3D US was 25.3 ml after fasting and 6.6 ml after a high-fat meal. The mean gallbladder contractility index was 77.7% on cholescintigraphy (range, 18-99) and 73.4 on 3D US (range, 16.7-97.3). A linear correlation between cholescintigraphy and 3D US contractility indices was observed. The r value on Pearson analysis was 0.92 and R(2) of the coefficient of determination was 0.85. The difference in measured contractility between the 2 methods ranged from +21.5% to -15.0% (mean +/- SD, 4.4 +/- 8.7%). CONCLUSIONS: 3D US is a reliable and easy method for clinical measurement of the volume of the gallbladder and its contractility.     

严格控制输液对干预早产儿发生硬肿、水肿的临床观察

目的：探讨输液量及输液方式与新生儿硬肿、水肿发生的相关性,寻找适合早产儿输液的最佳方式。方法选取62例胎龄34~36+5周,体重≥2 kg的早产儿为研究对象,通过新生儿室护士对新生儿输液量及输液速度的控制,比较不同输液方式是否对治疗有影响,按随机数字表法随机分为A、B 、C三组。 A组：控制总入量,按常规速度输液(5~6滴/min);B组：采用微量注射泵控制输液速度;C组：采用微量注射泵24 h持续泵入控制输液速度,然后在静脉留置针患儿中对比,观察其疗效。三组液体量控制方法均为生后1~3d总入量(包括奶量、饮水及输液量)分别为50 ml/kg、60 ml/kg、80 ml/kg,4~7 d 100 ml/kg,每天根据患儿摄入奶量和饮水量调整输液量,输液量也包括肠外营养液：氨基酸、脂肪乳,所有用量均参照新生儿静脉营养治疗要求配置浓度〔2〕。结果 C组(采用微量注射泵24 h持续泵入)治疗效果最好,水肿、硬肿的程度及输液并发症减轻、患儿的总费用降低、平均住院时间缩短( P<0.05)。此方法优于A组(控制总入量,按常规速度输液5~6滴/min )、B组(微量注射泵控制输液速度,液体输入完成后结束本日治疗,不需要24 h持续泵入),值得临床推广应用。结论 C组(采用微量注射泵24 h持续泵入)疗效最好,水肿、硬肿并发症最轻。     

Gallbladder contractility in patients with cirrhotic versus malignant ascites

PURPOSE: The aim of this study was to evaluate differences in gallbladder contractility by measuring gallbladder wall thickness, fasting and residual gallbladder volume, and gallbladder ejection fraction in patients with cirrhotic and malignant ascites. METHODS: Twenty-four patients (16 women and 8 men) with malignant ascites (2 cervical, 2 colon, 2 stomach, 6 pancreatic, and 12 ovarian carcinomas), aged 59 +/- 12 years, and 26 patients (14 women and 12 men) with cirrhotic ascites, aged 57 +/- 16 years, were included in the study. After patients fasted overnight for 8 hours, gallbladder wall thickness, fasting gallbladder volume, and gallbladder volume and ejection fraction were measured sonographically at 10, 20, 30, 40, 50, 60, 70, 80, and 90 minutes after ingestion of a standard liquid test meal. RESULTS: The mean gallbladder wall thickness was higher in patients with cirrhotic ascites than in those with malignant ascites (5.5 +/- 1.5 mm [standard deviation] versus 3.1 +/- 0.6 mm, respectively; p < 0.001). The mean fasting gallbladder volume was also higher in patients with cirrhotic ascites than in those with malignant ascites (27.3 +/- 11.5 cm(3) versus 17.6 +/- 8.9 cm(3); p < 0.05). Patients with cirrhotic ascites had significantly higher mean postprandial gallbladder volumes and ejection fractions than did those with malignant ascites at all times except 10 minutes after the meal (p < 0.05). CONCLUSIONS: Our findings suggest that gallbladder contractility is greater in patients with cirrhotic ascites than in patients with malignant ascites.     

Power-Injectable Peripherally Inserted Central Catheter Tip Malposition After Power Injection of Intravenous Contrast Media for Computed Tomography Examinations

The aim of this study is to describe the incidence of peripherally inserted catheter tip (PICC) migration after power injection of intravenous contrast for computed tomography (CT) examinations. Retrospective review was conducted of all PICC power injections for CT examinations during the study period: October 16, 2017 through October 23, 2018. Review included evaluation of preinjection and postinjection topograms to assess PICC tip position. Chi-squared statistical analysis was applied. A total of 594 topograms were obtained of power-injectable PICCs during the study period in anticipation of power injection with iodinated contrast media. Of those, 550 patients had satisfactory preinjection topograms and available postinjection topograms; 43 (7.8%) demonstrated tip malposition attributable to power injection of contrast media. Anatomic side of PICC placement and subsequent malposition were independent variables by chi-square test (chi-square = .09, P = .76); 32 of 429 (7.5%) right-sided PICCs versus 11 of 121 (9.1%) left-sided PICCs demonstrated new malposition after contrast media power injection. No complications related to power injection of contrast media through these PICCs were observed. PICC tip malposition secondary to power injection of iodinated contrast media is common and readily identifiable. Obtaining both preinjection and postinjection topograms ensures appropriate catheter position during injection and upon patient departure. Rapid saline flush is a noninvasive maneuver that allows a high chance of successful repositioning of catheter tips. Power injection of contrast media through a power injectable PICC is safe.     

Contrast material and gallbladder kinetics: implications for same day sonography after intravenous pyelography or CT scanning.

Sonographic examination of the gallbladder has allowed us to study the effects of various substances on this organ. A prospective study involving 77 patients was undertaken to evaluate the effects of intravenous or oral contrast agents on gallbladder volume changes in patients without known gallbladder disease. A mean volume after contraction of 24.8% was observed after administration of intravenous contrast agent (P < 0.01) and of 31.9% after oral administration (P < 0.01). This phenomenon of contraction of the gallbladder should therefore be recognized when sonographic or computed tomographic evaluation of the gallbladder is undertaken after imaging procedures that use radiographic contrast agents either intravenously or orally.     

造影剂在数字减影血管造影（DSA）中的应用

目的:总结在DSA检查时造影剂应用方面的体会和经验。材料和方法:共行DSA 2560人次,其中男性1850例,女性710例,年龄5个月到85岁,包括动脉和静脉造影。其中用离子型造影剂2100人次,非离子型造影剂460人次。结果:造影剂注射次数1—12次不等,平均4次,造影剂用量10—180ml,平均58ml。DSA质量评价:优等为85％,中等为13％,差为2％。副反应:离子型造影剂组和非离子造影剂组分别为4.8％和1.4％。无一例死亡。结论:对不同部位进行造影时应选择合适的造影剂,既考虑安全又考虑到病人的经济情况,选择适当的流速流量,既显示血管及其病变,又减少过敏反应及不适感的发生。     

Contrast-enhanced power Doppler sonography: improved detection of characteristic flow patterns in focal liver lesions

PURPOSE: The aim of this study was to evaluate whether intravenous injection of an ultrasound contrast agent aids in the visualization of focal liver lesions on power Doppler images. METHODS: Fifty patients with focal liver lesions were studied by B-mode and power Doppler sonography before and after intravenous injection of the contrast agent Levovist (galactose-based microbubbles; 10 ml of a concentration of 300 mg/ml). Thirty-two patients had malignant liver lesions (19 metastases, 12 hepatocellular carcinomas, 1 cholangiocellular carcinoma), while 18 had benign lesions (12 hemangiomas, 2 focal nodular hyperplasias, 4 others). RESULTS: After contrast medium injection, the number of lesions with no intralesional flow dropped from 18 to 9. Flow signal intensity was rated subjectively as marked on contrast-enhanced images in 17 patients; only 4 patients had marked flow on precontrast images. On precontrast studies, central flow in 10 lesions and peripheral flow in 29 lesions could be observed. After enhancement, the numbers increased to 18 and 34 lesions, respectively. CONCLUSIONS: On power Doppler images, a greater number of intratumoral vessels are seen in focal liver lesions after contrast medium administration.     

Omnipaque (iohexol).

The largest nationwide comparative clinical study evaluated 337,647 patients receiving high-osmolar ionic contrast media or low-osmolar nonionic contrast media and the incidence of adverse drug reactions. The overall prevalence of adverse drug reactions was 12.66% in the ionic contrast media group and 3.13% in the nonionic contrast media group. Severe adverse drug reactions occurred in 0.22% of examinations in the ionic contrast media group and in 0.04% of examinations in the nonionic contrast media group. Thus, the use of nonionic contrast medium significantly reduces the frequency of severe and potentially life-threatening adverse drug reactions to contrast media.     

多层螺旋CT及双期增强扫描对大肠癌术前分期价值研究

目的:评价大肠低张充气多层螺旋CT结肠重建成像及双期增强扫描在大肠癌术前分期中的应用价值。方法:对35例经纤维内镜检查证实或临床高度怀疑大肠癌患者进行MSCTC及双期动态增强扫描检查。利用MSCTC后处理图像,并结合各期横断面图像,根据肿瘤原发病灶、淋巴结和远处转移情况进行分期(TNM分期),并与手术病理结果对照。结果:本组多层螺旋CT研究显示对大肠癌T期敏感性100%(35/35),T期的准确率91.4%(32/35)。N期的敏感性80.0%(16/20),N期准确率75.0%(15/20)。4例肝脏转移经CT检出。结论:大肠癌术前MSCTC成像及结合各期横断面图像,能进行准确术前分期,并为临床提供立体准确的影像学信息。     

多排螺旋CT的肝脏灌注时间的研究

目的利用多层螺旋CT观察肝脏在不同条件下的血流灌注情况。方法45个健康志愿者分三组,A组:速率2ml/s,剂量30ml;B组:速率4ml/s,剂量30ml;C组:速率4ml/s,剂量60ml。注射后10s在肝门区行8排螺旋容积扫描,间隔2s,至120s。分别测肝门区同一解剖层面主动脉、肝动脉、门静脉和肝实质的增强前后的CT值,将每组内各时间点的强化CT值平均,得到它们强化的平均峰值及到达峰值的平均时间和肝实质平衡时的平均CT值及到达的时间。并绘出它们的时间—强化曲线图。结果主动脉、肝动脉、门静脉、肝实质平均到达峰值时间分别为22.5s,25s,37.5s,45s在A组和C组,20s,22.5s,30s,35s在B组。肝实质到达平衡期的平均时间A组、B组、C组时分别为60s,40s,60s。结论肝及血管强化程度受对比剂量正比影响;剂量相等时,肝、血管强化到达的峰值时间与注射速率成反比;注射时间相等,强化峰值与注射速率成正比,但到达的峰值时间不变;注射速率相同时,注射时间的延长,峰值时间随之落后。建议在4ml/s速率下,多排螺旋CT肝脏检查,动脉期、门脉期及平衡期时间窗的选择设定在注射对比剂后25,40,65s为宜。     

The influence of induced hyperglycaemia on gastric emptying rate in healthy humans

The effect on gastric emptying rate (GER) of elevated plasma glucose was investigated in eight healthy non-diabetics. They received intravenous infusions of 1000 ml 10% glucose (555 mmol, 1720 kJ) in 2 h: one-half before and the rest during the measure of GER. A control group was established with infusion of hypertonic sodium chloride and in a third group the GER was measured twice without infusion. GER was measured after 6 h of fasting, and following ingestion of a 100 g omelette (1400 kJ) tagged with 40 MBq 99mTc-sulphur colloid and 150 ml water with 8 MBq 111In-DPTA. Anterior and posterior recordings were made on gamma camera every 10th min during 1 h. Time-activity curves from the gastric area were generated for solid and liquid phases, respectively, using geometric means. The GER of solids was delayed, at least partly, by prolongation of the lag phase, and the GER of liquids was delayed following the intravenous infusion of glucose. The GER of solids was delayed following hypertonic saline infusion but not to the same extent as followed glucose in spite of the double osmotic load of saline. The percentage delay of GER of solids following glucose infusion was related to the increase in plasma glucose.     

Impaired fatty-meal-stimulated gallbladder contractility in patients with Crohn's disease.

1. The incidence of gallstones in patients with Crohn's disease is increased compared with that in healthy control subjects. This is in part due to reduced terminal ileal bile salt absorption and consequent increased cholesterol saturation in bile. The aim of this study was to evaluate gallbladder contractility, a second important factor in the pathogenesis of gallstones, in Crohn's disease. 2. Thirty patients with Crohn's disease and no known biliary tract disease and nine healthy control subjects were studied. After an overnight fast, gallbladder volume was determined by real-time ultrasonography before and 10, 20, 30, 40, and 50 min after ingestion of a standard liquid fatty meal. 3. Compared with healthy control subjects, patients with Crohn's disease had similar fasting gallbladder volumes (control, 18.7 +/- 2.3 ml; Crohn's disease, 18.2 +/- 2.3 ml). Percentage emptying was significantly impaired at 30, 40 and 50 min in patients with Crohn's disease compared with control subjects. Patients with Crohn's disease limited to the small bowel had gallbladder contractility that was comparable with that of control subjects, whereas in those with large-bowel disease, minimum residual gallbladder volume was significantly smaller than in control subjects. Patients with both large- and small-bowel Crohn's disease demonstrated the most marked abnormalities, with gallbladder volumes significantly larger than those of control subjects at 30, 40 and 50 min. Likewise, patients with Crohn's disease who had undergone previous bowel resection had impaired emptying at 30, 40 and 50 min.(ABSTRACT TRUNCATED AT 250 WORDS)     

Bowel endometriosis: CT-enteroclysis

Although several radiological techniques have been used for the diagnosis of bowel endometriosis, no gold standard is currently established. We used multislice computerized tomography (CT) combined with the distention of the colon by rectal enteroclysis (MSCTe) for the diagnosis of bowel endometriosis. Following bowel preparation, pharmacological hypotonicity, retrograde colonic distention by water enteroclysis, and intravenous injection of iodinated contrast medium, a single volumetric acquisition of the abdomen is performed. MSCTe findings suggestive of bowel endometriosis are the presence of solid nodules with positive enhancement, contiguous or penetrating the colonic wall. When endometriotic lesions are detected, the degree of infiltration of the intestinal wall can be estimated; however, the depth infiltrated by nodules reaching the submucosa may be underestimated. MSCTe is well tolerated by the patients. The strength of MSCT consists in the high spatial resolution; volumetric data acquired by using thin slices provide isotropic voxels and multiplanar reconstructions have a quality comparable with that of the original axial scans. The potential of MSCTe for the diagnosis of bowel endometriosis relies on the fact that the serosal, muscular, and mucosal layers of the bowel wall can be evaluated.     

胃三维容积超声造影与上消化道碘水造影在G-POEM手术疗效评估中的价值分析

目的 探讨胃三维容积超声造影与上消化道碘水造影在G-POEM手术疗效评估中的价值,从而为临床选择更合适的影像学检查方法。 方法 经东南大学附属中大医院消化科医生确诊胃轻瘫且需要进行G-POEM手术的患者共93例,根据胃排空检查方法的不同分为A组（超声胃三维容积检查）和B组（X线碘水造影检查）,其中A组48例、B组共46例,A组口服超声造影剂后在5min、15min、30min、60min及90min时间点时进行超声测量,B组在口服碘水造影剂后在上述相同时间点进行上腹部平片,上述方法在G-POEM手术前、后各测量一次,分别得到三维超声造影方法及碘水造影方法估测的G-POEM手术前、后的胃容积,从而各自评估G-POEM手术的有效后的胃排空改善情况,并进行比较分析。 结果1、完成A组胃三维超声造影方法检查的成功率为97.9%,完成B组上消化道碘水造影检查的成功率为97.8%,两组检查成功率没有统计学差异（P＞0.05）;2、A组检查中胃排空时间明显减少的有效例数为31例,胃排空时间由术前的90（90,90）min减少至术后的30（15,60）min（P＜0.05）,B组检查中胃排空时间明显减少的有效例数为31例,胃排空时间由术前的90（90,90）min减少至术后的30（15,60）min（P＜0.05）。3、A组术前及术后排胃空时间均为90min的16例患者中,90min时间点测量时胃排空率较术前明显改善的有效例数为8例,由术前的61.6%（55.9%,73.6%）增加至术后的78.1%（74.1%,91.6%）（P＜0.05）,胃排空无明显改善的例数为8例（P＞0.05）, B组术前及术后排空时间均为90min的14例患者中,90min时间点测量时胃排空率较术前明显改善的有效例数为5例,由术前的25.0%（25.0%,50.0%）增加至术后的75.0%（70.0%,90.0%） (P＜0.05),胃排空无明显改善的例数为9例（P＞0.05）。4、A组47例超声造影患者中有39例患者的胃排空情况得到了改善（P＜0.05）,其中31例患者的胃排空情况较术前显著改善,8例患者的胃排空情况得到了改善,另8例患者的胃排空情况没有得到改善（P＞0.05）;B组45例碘水造影患者中有36例患者的胃排空情况得到了改善（P＜0.05）,其中31例患者的胃排空情况有明显的改善,5例患者的胃排空情况得到了改善,另9例患者的胃排空情况没有得到改善（P＞0.05）。A、B两组影像学检查评估结果的G-POEM手术后胃排空改善有效率分别为83.0%、80.0%,两组影像学检查结果没有明显差异(P＞0.05)。 结论 胃三维超声容积测定方法及上消化道碘水造影方法均可以对G-POEM前后的胃排空情况进行评价,两种方法的成功率及评估G-POEM手术后的胃排空改善率符合率没有明显差异性,那么由于超声的独特优势（无辐射/操作简便/患者接受度高等）,临床可首选超声胃三维容积检查方法评估G-POEM手术前后的胃排空情况,从而评价G-POEM手术后胃排空功能的改善效果,上消化道碘水造影检查方法作为补充方法,为临床提供客观的影像学数据。     

硫酸镁不同服用方法对静脉肾盂造影检查前肠道准备的效果评价

目的 探讨口服50%硫酸镁 60 ml后最佳的饮水量、饮水方式、饮水时限对静脉肾盂造影(intravenous pyelography,IVP)检查前肠道准备的效果分析.方法 将2009年6月至2010年2月准备行IVP检查的200例患者在知情同意的前提下喝完50%硫酸镁60 ml,并被分成4组.A组:1 h内分次大量口服1200 ml温开水;B组:1 h内小量任意服1200 ml温开水;C组:1 h内分次大量口服2000 ml温开水;D组:2 h内分次中量口服1200 ml温开水.然后将4组肠道准备的效果进行分析.结果 通过对各组的对比,A组在满意度、阅片有效度及胀气有效度等指标上要比其他组好.结论 服药后在1 h内分次大量口服1200 ml温开水能提高导泻的满意度、阅片的有效度、胀气的有效度,值得临床推广应用.

Abstract：

Objective To analyze optimal amount of drinking water,ways of drinking water,timelimit of drinking water on the effect of bowel preparation for intravenous pyelography (IVP) examination after oral administration of 50% magnesium sulfate 60 ml. Methods 200 patients who gave their consentfrom June 2009 to February 2010 drank 50% magnesium sulfate 60 ml for IVP check were divided into four groups. Group A: a large amount of graded oral administration of warm water 1200 ml within 1h; Group B: a small amount of oral administration of warm water 1200 ml within 1h;Group C: a large amount of graded oral administration of warm water 2000 ml within 1h; Group D: a medium amount of graded oral administration of warm water 1200 ml within 2 h. And then the bowel preparation effect of the four gro ups were analyzed. Results Through the comparison, group A was much better than the other groups on the aspects of cathartic satisfaction, the effective degree of reading films and flatulence. Conclusions To take a large amount of graded oral administration of warm water 1200 ml within 1h can improve cathartic satisfaction,the effective degree of reading films and flatulence.     

增强CT扫描与FDG-SPECT/PET扫描诊断 小肺癌的比较性研究

目的:探讨增强CT扫描与FDG-SPECT/PET显像(氟-18-脱氧葡萄糖-单光子发射计算机断层/正电子发射计算机断层显像)对小肺癌诊断的意义.方法:病理证实的小肺癌11例,炎性结节5例,结核瘤2例,术前行CT增强扫描(100mg造影剂以2.5ml/s速度静脉注射)和FDG-SPECT/PET显像(FDG11.1-14.8MBq静脉注射),观察病灶CT图像强化程度及核素显像的FDG浓聚程度,将术前两种不同的扫描结果与术后的病理结果进行对照,分析两种方法对鉴别诊断小肺癌的意义,结果:11例小肺癌增强CT扫描及FDG显像均诊断正确 ,但增强CT将1例炎性假瘤误诊为肺癌,FDG将一例结核误诊为肺癌,在11例小肺癌中CT检出6例伴有纵隔淋巴结转移,FDG检出5例淋巴结转移.结论:增强CT扫描与FOG-SPECT/PET显像均能鉴别 诊断小肺癌,两者各有优势,其正确率无显著差异,两种方法结合分析将更有利于沔肺癌的鉴别诊断.     

“Essential” hypernatremia due to ineffective osmotic and intact volume regulation of vasopressin secretion

A physiological explanation for sustained hyperosmolality was sought in a patient with histiocytosis. During 23 days of observation with only sodium intake regulated at 100 mEq daily, elevation (mean 310 mOsm/kg of water) and fluctuation (range 298-323) of the fasting plasma osmolality were recorded. The presence of endogenous vasopressin was indicated by the patient's ability to concentrate the urine to as high as 710 mOsm/kg of water with a creatinine clearance of 84 cc/min, and by dilution of the urine in response to alcohol. The failure of increasing fluid intake to as high as 6.2 liters daily to lower the plasma osmolality indicated that deficient fluid intake was not solely responsible for the elevated plasma osmolality. Hypertonic saline infusion during water diuresis resulted in the excretion of an increased volume of dilute urine. The water diuresis continued despite a rise in plasma osmolality from 287 to 339. An isotonic saline infusion initiated during hydropenia resulted in a water diuresis which continued despite a rise in the plasma osmolality from 303 to 320. Stable water diuresis induced during recumbency by either oral ingestion of water or intravenous infusion of normal saline was terminated by orthostasis and resumed with the return to the recumbent position. Antecedent alcohol ingestion blocked the antidiuresis of orthostasis. The data are interpreted as indicating impairment of the osmoreceptor mechanism as the primary cause of the hyperosmolar syndrome. They also indicate that vasopressin secretion was regulated primarily by changes in effective blood volume. Chlorpropamide was found to be an effective treatment for the syndrome.