[Laparoscopic cholecystectomy in patients with earlier laparotomy]. / Laparoskopisk kolecystektomi hos patienter med tidligere laparotomi.

Previous abdominal surgery has been reported as a relative contraindication to laparoscopic cholecystectomy. A retrospective analysis of 356 laparoscopic cholecystectomies was undertaken to determine whether previous abdominal surgery led to increased morbidity. The results of 116 patients who had had previous abdominal surgery were compared with those of 240 patients without previous abdominal surgery. The rate of conversion to open operation was not increased. The operating time was a little increased. There were no increases in either minor or major postoperative complications in patients with previous abdominal surgery, and the in-hospital stay time was the same. The median recovery time was respectively ten versus eight days in patients with and without previous surgery. We conclude that previous abdominal surgery is not a contraindication to laparoscopic cholecystectomy.

[Primary experiences with laparoscopic appendectomy]. / Primaere erfaringer med laparoskopisk appendektomi.

The material comprises 77 patients with suspected appendicitis seen in a district community hospital. In the presence of a surgeon with laparoscopic experience laparoscopy was performed in 23 patients. In two patients the laparoscopy was only diagnostic, and in two patients adhesions or friable gangrenous appendicitis necessitated conversion to conventional appendicectomy. Nineteen patients thus had a laparoscopic appendicectomy performed with a median operation time of 63 minutes and a median hospital stay of two days. One patient with gangrenous appendicitis and a periappendicular abscess was readmitted after three weeks because of deep infection, which resolved after antibiotic treatment. The remaining 54 patients had a conventional appendicectomy performed, with a median operation time of 40 minutes and a median hospital stay of three days. There were six complications in this group. We conclude that laparoscopic appendicectomy is a safe alternative to open operation with benefits for the patient in form of lesser pain, shorter hospital stay, fewer complications, better cosmetic outcome, and shorter time to normal activity.

Reflectance pulse oximetry measurements from the retinal fundus.

Conventional transmission pulse oximetry is a noninvasive technique for the continuous monitoring of arterial oxygen saturation (SaO2) from peripheral vascular beds such as the finger tip or earlobe. In this paper we propose to exploit the unique transparency of the ocular media to make reflectance pulse oximetry measurements on the retinal fundus. This technique potentially offers significant advantages over conventional pulse oximetry, primarily the ability to monitor cerebral, as opposed to peripheral, oxygen saturation. We have developed an in vitro system to stimulate the retinal circulation and ocular optics. This system consists of a flexible cuvette located in a model eye and an extracorporeal blood circuit to stimulate arterial blood flow. The system was used to investigate the relationship between SaO2 and the R/IR ratio in reflectance pulse oximetry. To enable in vivo measurements to be made, we also modified a standard haptic contact lens to hold the pulse oximeter probe in front of the pupil. In a preliminary study, the lens was fitted to an awake volunteer and cardiac-synchronous signals were detected by the retinal pulse oximeter.

Pulse oximetry: theoretical and experimental models.

In the paper a pulse oximetry model is developed using an approach which combines both theoretical and empirical modelling. The optical properties of whole blood are measured as a function of cuvette depth by transmission spectrophotometry using red (660 nm) and infra-red (950 nm) light-emitting diodes as light sources. Twersky's theoretical model gives the best fit to the experimental data. A simple theoretical model which takes into account the nonlinear relationship between optical density and cuvette depth is then used to obtain an expression for the R:IR ratio, which relates the measurement of transmission at the two wavelengths. The R:IR ratio is found to be more or less independent of cuvette depth (SD = 0.14 at 100 per cent SaO2). To validate the predictions of the theoretical model, the results of a previous experiment in which the relationship between SaO2 and the R:IR ratio was recorded using a flexible cuvette are used. The experimental values are found to lie within one standard deviation from the theoretical curve relating SaO2 and the R:IR ratio. It is argued that a reasonably accurate model for pulse oximetry which is based on whole blood and not haemoglobin solutions has been developed.

[Non-surgical treatment of acute cholecystitis in high-risk patients. Percutaneous drainage of the gallbladder and removal of stones]. / Ikke-operativ behandling af akut kolecystit hos højriskopatienter. Perkutan galdebloeredroenage og stenfiernelse.

Eight high-risk patients with acute cholecystitis were submitted to subhepatic percutaneous drainage of the gall-bladder as the initial treatment. One patient died a few days after the intervention. Six patients had stones in the gall-bladder. Cholecystectomy was performed in one of these in five, the stones were removed by a percutaneous endoscopic technique after dilatation of the drainage canal. No noteworthy complications occurred.

Temperature dependence of led and its theoretical effect on pulse oximetry.

Ambient temperature is known to affect the emission spectrum of a light-emitting diode (LED). This study has investigated the effect of changes in ambient temperature on the emission spectra of two LED with peak emission wavelengths similar to those used in pulse oximetry. There was a 5.5-nm increase in the peak wavelength for a 660-nm LED, and a 7.8-nm increase in the peak wavelength for a 950-nm LED as temperature increased from 0 to 50 degrees C. Using a simple theoretical model based on the Beer-Lambert law, the effect of these shifts in wavelength on pulse oximeter accuracy was examined and found to be negligible over the temperature range studied.

The effect of varying LED intensity on pulse oximeter accuracy.

Most pulse oximeters automatically alter the intensity of their light-emitting diodes (LEDs) according to the absorption of the finger, toe or earlobe to which they are attached. This paper investigates the effect of changing LED intensity on pulse oximeter accuracy. Our results show that the peak wavelength of a red LED typically increases by 8 nm as its intensity is increased ten-fold. To determine whether this shift introduces a significant error, a simple theoretical model based on the Beer-Lambert law is used. The model predicts that a 10:1 change in LED intensity results in a 2.5% error at 50% arterial oxygen saturation (SpO2). At high saturations (SpO2 greater than or equal to 85%) the model predicts little loss of accuracy and thus any effect due to changes in LED intensity will be apparent only at low saturations.

In vitro investigation of the factors affecting pulse oximetry.

The effect of a number of physiological parameters on pulse oximetry accuracy has been investigated in an in vitro model. We have found that above 50% saturation, pulse oximeters will not be affected by variations in haematocrit, blood flow rate, tissue blood content and pulse amplitude. At low saturations, however, it is known that the accuracy of pulse oximeters decreases and our in vitro results suggest how this may be corrected.

[Percutaneous cholecystostomy and laser lithotripsy]. / Perkutan kolecystostomi og laser-litotripsi.

A case of acute cholecystitis in a high risk patient was treated in the acute phase with cholecystostomy guided by ultrasound and with introduction of a pig-tail catheter for drainage. Later, percutaneous laser lithotripsy was undertaken via a flexible choledochoscope. The recent percutaneous therapeutic principles and the possibilities in biliary calculous disease are reviewed.

Operative pressure profile at Oddi's sphincter and in the choledochus duct through the cystic duct (development of a normal curve).

With the aid of 14 patients, it was attempted to develop a normal curve for pressure conditions at Oddi's sphincter and in the choledochus duct. However, because of limited patient material, it was not possible to interpret deviations from the normal curve and relate these to confirmed pathological conditions.