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Biomedical subjects

S F Zakko

Publications and source records attributed to S F Zakko.

9 recordsLinked to original sources
PubMed1999

A comparison of midazolam and diazepam for conscious sedation during colonoscopy in a prospective double-blind study.

BACKGROUND: Midazolam and diazepam are commonly used for conscious sedation, but their comparative respiratory depressive effects have not been accurately studied. We used a novel real-time, on-line, computerized data acquisition system to compare the two agents in a randomized double-blind study. METHODS: One hundred patients undergoing colonoscopy were studied. The maximum end-tidal carbon dioxide tension (PetCO2) and the minimum oxygen saturation by pulse oximetry (SpO 2) were recorded by computer every minute. Patients received meperidine (25 to 50 mg) and incremental doses of either midazolam or diazepam to an identical end point of slurred speech and/or ptosis. Sedation was scored from 1 (unarousable) to 5 (wide awake). RESULTS: Sedation scores were 3.6 +/- 0.1 (mean +/- standard error) after each agent. The doses of midazolam and diazepam were 0. 031 +/- 0.002 and 0.106 +/- 0.009 mg/kg, respectively. In the first 45 minutes (PetCO2) was significantly higher with midazolam than with diazepam (p < 0.05). SpO2 was significantly depressed for 80 minutes after each agent, and the number of minutes when the minimum Sp O2 was less than 90% did not differ between the two agents. CONCLUSIONS: Midazolam was 3.4 times more potent than diazepam. The duration of oxygen desaturation emphasizes the importance of monitoring SpO2 until ventilation and oxygenation have recovered. Although the degree of hypoxemia was comparable, midazolam led to higher end-tidal carbon dioxide tensions.

Adult↗
PubMed1997

Ethyl propionate is more effective and less cytotoxic than methyl tert-butyl ether for topical gallstone dissolution.

BACKGROUND & AIMS: Ethyl propionate and isopropyl acetate were identified as gallstone solvents with more favorable physicochemical properties than the currently used solvent methyl tert-butyl ether (MTBE). In this study, their efficacy and toxicity were compared. METHODS: To compare efficacy, matched stones from 33 patients were subjected to dissolution with each solvent. To evaluate cytotoxicity, jejunal segments of the anesthetized rat were exposed to each solvent or saline; the segments were then perfused with markers for active absorption and passive permeability. RESULTS: For 23 gallstone sets that dissolved completely with all three solvents, the average dissolution time was shorter with ethyl propionate (38 +/- 8 minutes) than with MTBE (60 +/- 13 minutes) (P = 0.03) or isopropyl acetate (55 +/- 12 minutes) (P < 0.001). Four stones did not dissolve with ethyl propionate, seven with MTBE, and eight with isopropyl acetate. After 2 minutes of exposure to the solvents, the dry weight of the segments decreased by 36% after MTBE but was unchanged after the other two solvents (P < 0.001). MTBE caused more inhibition of active absorption than the other solvents (P < 0.001) and a greater increase in passive permeation (P < 0.03). CONCLUSIONS: Ethyl propionate and isopropyl acetate are less toxic to the intestinal mucosa than MTBE, and ethyl propionate is more effective for gallstone dissolution.

Acetates↗
PubMed1997

Local and systemic effects of intraduodenal exposure to topical gallstone solvents ethyl propionate and methyl tert-butyl ether in the rabbit.

During topical dissolution of gallstones, solvent can escape to the duodenum causing toxic effects that have not yet been adequately quantified. We compared the local intestinal cytotoxic and systemic hepatotoxic effects of two gallstone solvents, methyl tert-butyl ether and ethyl propionate, on the rabbit's duodenum. Methyl tert-butyl ether, ethyl propionate, or saline (control) was infused intraduodenally for 3 hr in 32 male New Zealand rabbits. The solvents were infused either at a high infusion rate of 8.5 microl/min or at a low rate of 4.0 microl/min. Blood samples were collected for biochemical analysis from each animal before and after the 3-hr infusion period. A standardized histologic scoring system was used by a pathologist blinded to the treatments to quantify liver and intestinal tissue injury. None of the animals studied showed any significant changes in serum alkaline phosphatase, amylase, bilirubin, or their hepatic histology or histologic scoring for mucosal necrosis and ulceration. At the higher dose, methyl tert-butyl ether produced significantly more submucosal inflammation (P = 0.0017) and showed a trend of causing more submucosal edema than ethyl propionate, but ethyl propionate led to significantly higher elevations of aminotransferases than methyl tert-butyl ether as compared to saline. There were no detectable blood levels of methanol or ethanol in any of the animals studied. Ethyl propionate may be less damaging to the intestinal mucosa of the rabbit than methyl tert-butyl ether, but at the higher dose (equivalent to 60 ml/3 hr in a 70-kg human) it appears to produce more biochemical liver injury when administered intraduodenally.

Administration, Topical↗
PubMed1995

Sensitivity of percutaneous endoscopy compared with ultrasonography in the detection of residue or mucosal lesions after topical gallbladder stone dissolution.

BACKGROUND: Early gallstone recurrence in some patients after "successful" percutaneous topical dissolution may be due to residual debris. An endoscope small enough to be introduced without dilating the existing percutaneous track was used for gallbladder examination after stone dissolution. METHODS: The sensitivity of gallbladder endoscopy was compared with ultrasonography and double-contrast cholecystography for the detection of residual debris or mucosal lesions in 18 patients who underwent percutaneous topical dissolution. All examinations were performed before catheter removal and after the gallbladder was deemed stone-free by the traditionally employed technique of single-contrast cholecystography. RESULTS: Residual debris was detected in only one patient by ultrasonography and in none of the 18 patients by double-contrast cholecystography, yet endoscopy showed stone fragments ranging from 1 to 3 mm in 13 of the 18 patients. In all these patients, catheter repositioning and additional solvent perfusion resulted in elimination of the debris as assessed endoscopically. Two patients had endoscopically detected erosions. Double-contrast fluoroscopy found only one of these, whereas ultrasonography detected neither. CONCLUSIONS: Percutaneous gallbladder endoscopy is a more sensitive imaging modality for the detection of residual stone debris or mucosal lesions after gallstone dissolution.

Cholecystography↗
PubMed1991

Contact dissolution of cholesterol gallstones with organic solvents.

Contact dissolution of cholesterol gallstones with organic solvents is emerging as a rapid, safe, alternative treatment for symptomatic cholesterol gallbladder stones. Placement of a percutaneous transhepatic catheter into the gallbladder is a rapid and safe technique. The availability of safe, effective cholesterol solvents and solvent transfer devices means that cholesterol gallbladder stones can be eliminated rapidly and safely by CDOS, without the risk of general anesthesia or surgical dissection of the gallbladder bed. Patients with single gallstones are better candidates for CDOS than are patients with multiple gallstones because recurrence after dissolution is less common. Contact dissolution may well be judged the treatment of choice by the medical-surgical gallstone management team in some patients.

Caprylates↗
PubMed1990

Microprocessor-assisted solvent-transfer system for gallstone dissolution. In vitro and in vivo validation.

To improve the efficacy, safety, and convenience of contact dissolution of gallbladder stones, a microprocessor-assisted solvent transfer system was developed. The system's two pumps simultaneously infuse and aspirate solvent into and from the gallbladder at a high flow rate through a multilumen catheter. The microprocessor controls the pumps using a closed feedback loop control algorithm to regulate intragallbladder pressure to prevent solvent escape into the duodenum. Turbulent solvent flow at the catheter end in the gallbladder is designed to induce rapid stone dissolution and to suspend insoluble residue, thus promoting its aspiration. The system's response and gallbladder emptying capacity was 160-fold faster than the natural gallbladder emptying rate. The rate at which gallstones were dissolved by methyl tert-butyl ether using the system was compared with that achieved with a syringe pump. For 6 of 11 pairs of stones that totally dissolved, the mean dissolution time with the system was 10 +/- 6 minutes compared with 112 +/- 81 minutes for the syringe pump. In the 5 of 11 stone pairs which dissolved incompletely, insoluble residue was completely eliminated by the system in 21 +/- 9 minutes but not by the syringe pump even at 360 minutes. When the system was used in gallstone patients, solvent recovery was 99% +/- 1%, and the concentration of a nonabsorbable marker did not change, confirming the lack of appreciable absorption of methyl tert-butyl ether. These studies suggest that the microprocessor-assisted solvent transfer system is a device capable of safe, complete, and fully automatic contact dissolution of cholesterol gallbladder stones using methyl tert-butyl ether or similar solvents.

Catheterization↗
PubMed1990

Microprocessor-assisted solvent transfer system for effective contact dissolution of gallbladder stones.

Dissolution of cholesterol gallbladder stones by manual lavage with methyl tert-butyl ether (MTBE) via a percutaneous indwelling gallbladder catheter is reviewed. The procedure is labor intensive and requires several hours, is associated with escape of solvent into the biliary tract, and is incomplete since residue remains. To solve these problems, a microprocessor-assisted solvent transfer (MST) system was developed. The system consists of a three-lumen catheter, dual peristaltic pumps, a pressure transducer, and a microprocessor controller which regulates pump rate according to the measured intraluminal gallbladder pressure. The two pumps simultaneously infuse and aspirate from the gallbladder via two of the catheter lumens; intraluminal pressure is monitored using the third lumen. An increase in intraluminal pressure above a set limit causes infusion to cease while aspiration continues, thus lowering the pressure and preventing overflow of gallbladder contents into the biliary tract. In vitro evaluation showed that the system's response was 156 fold faster than the natural rate of gallbladder emptying. The time required for gallstone dissolution by MTBE was measured in vitro using the MST system and found to be 48 +/- 23 (M +/- SE) min at 100 mL/min flow, 15 +/- 5 min at 150 mL/min flow, 12 +/- 4 min at 200 mL/min flow, and 6 +/- 1.4 min at 250 mL/min flow. No residual debris remained with flow rates greater than 150 mL/minute. These in vitro studies suggest that the MST system is capable of rapid, complete, and fully automatic contact dissolution of cholesterol gallbladder stones using MTBE or similar lipid solvents.

Cholelithiasis↗
PubMed1988

Gallbladder and bile duct stones: percutaneous therapy with primary MTBE dissolution and mechanical methods.

The authors describe percutaneous treatment of gallbladder or bile duct stones in 18 patients who were poor surgical candidates or in whom conventional therapy failed. Dissolution was performed in most cases with methyl tert-butyl ether (MTBE) because of its potent dissolution properties; other solvents used included monooctanoin or chelating solutions. Gallbladder stones were eliminated in 11 of 13 patients (six of seven with dissolution alone, four of four with dissolution and basket extraction, one with basket removal alone). In five patients with stones in the common bile duct (n = 3), cystic duct remnant (n = 1), and intrahepatic bile ducts (n = 1), stones were eliminated with dissolution alone in two and with dissolution plus basket extraction in one. In two patients percutaneous therapy failed due to complications (vagal hypotension with bile peritonitis and transient respiratory arrest) that occurred during catheter placement. Preliminary results suggest that MTBE is effective for dissolution of many gallbladder stones and some bile duct stones. Noncholesterol solvents and adjuvant mechanical maneuvers are valuable adjuncts to achieve complete stone elimination.

Bile Duct Diseases↗