Central venous catheters may be a potential source of massive air emboli during vascular procedures involving extracorporeal circulation: an experimental study.

Central venous catheters are mandatory during every major procedure involving extracorporeal circulation. Air emboli potentially could enter the circulation through this device when negative pressure is applied in the venous cannula. The following experimental study was initiated by a fatal massive air embolus during a vascular procedure involving cardiopulmonary bypass. An experimental setup was established, simulating a real scenario. The experiment was performed with a 40% glycerol/water mixture which exhibits properties and fluid dynamics close to blood. A heart-lung machine provided circulation of the fluid. The flow was adjusted according to the gravitational status. A triple-lumen central venous catheter with one line open to air was lowered into the liquid. The disconnected lumen of the central venous catheter was manipulated so it approached and was located in close proximity to the venous cannula. An air flow of up to 300 ml/min could be obtained from the central venous catheter with a flow in the cardiopulmonary bypass circuit of 2.3 L/min. A linear relationship was observed between flow in the circuit and air flow. Consecutive measurements proved consistent with acceptable results, proving that a disconnected central venous catheter might, under certain circumstances, be a source of massive air emboli during cardiopulmonary bypass.

A novel method for indirectly monitoring arterial pO(2) during cardiopulmonary bypass.

Arterial blood oxygen tension (P(a)O(2)) is a vital variable that has to be monitored during cardiopulmonary bypass (CPB). The aim of this study was to develop an alternative method for continuously P(a)O(2) monitoring during CPB, based on measurements of exhaust-gas from an oxygenator. A total of 15 adult patients undergoing CPB (n = 81 samples) were included in a study in order to develop an appropriate algorithm for P(a)O(2) estimation based on exhaust gas monitoring of the oxygen tension (P(ex)O(2)). The acquired data was used as a basis for developing a statistical prediction algorithm designed for continuously estimating the P(a)O(2)-level based on exhaust gas data in combination with data from the surrounding medical equipment. A new instrument was developed in order to implement this P(a)O(2) prediction algorithm and was tested on five patients (n = 39 samples). When the first sample was used for calibrating the instrument, the mean (SD) error was 8.7% (7.3%) with a 95% CI of 6.1-11.3%. Our results indicate that a pO(2)-exhaust monitoring device with adequate precision is obtainable, but further studies are required.

Evaluation of oxygenators and centrifugal pumps for long-term pediatric extracorporeal membrane oxygenation.

OBJECTIVE: Two extracorporeal membrane oxygenation (ECMO) circuits for children under 10 kg were evaluated and compared for plasma leakage, hemolysis, blood transfusions, and durability. METHODS: Group A (n=20) was supported by ECMO circuits with the Minimax oxygenator and the Biomedicus centrifugal pump. Group B (n=10) was supported by ECMO circuits with the Lilliput 2 ECMO oxygenator and the Rotaflow centrifugal pump. RESULTS: ECMO circuit durability, as measured by oxygenator lifespan, was significantly better in Group B than in Group A (p = 0.04). There was significantly lower hemolysis, measured by plasma free hemoglobin, in Group B (p = 0.019), and patients in Group B had significantly less need for antithrombin III transfusion (p = 0.004). No plasma leakage was observed in Group B oxygenators, but plasma leakage was observed in all Group A oxygenators. CONCLUSION: The combination of a Rotaflow centrifugal pump and Lilliput 2 ECMO oxygenator in pediatric ECMO circuits improved durability and reduced circuit-induced hemolysis. This improvement may be due to the low priming volume, the oxygenator's plasma leakage resistance, the suspended rotor of the centrifugal pump, or a combination of these factors.

Sterility of the uterine cavity.

In a prospective open study the sterility of the uterine cavity was evaluated in 99 women admitted for hysterectomy. The indications for hysterectomy were in most cases persistent irregular vaginal bleeding and fibromyomas of the uterus. Samples for both aerobic and anaerobic bacteria, Chlamydia trachomatis, yeasts and viruses were taken preoperatively from the apex of the vagina and cervical os. Immediately after hysterectomy the uterus was opened under sterile conditions and samples obtained from the isthmus and fundus of the uterine cavity for microbiological examination. Wet smears were taken from the same sites. Nearly a quarter of all the patients harbored one or more microorganisms in the uterus, mostly Gardnerella vaginalis, Enterobacter and Streptococcus agalactiae. We found that in a significant number of cases, the uterine cavity is colonized with potentially pathogenic organisms which may play a causative role in endometritis. The results indicate that inflammation of the uterine cavity should be evaluated by hysteroscopic examination before hysterectomy is undertaken in patients with persistent irregular vaginal bleeding.

Long-term stability of diazepam injections.

Diazepam and its main degradation product 2-methyl-amino-5-chlorobenzophenon (MACB) were quantitatively determined by HPLC and spectrophotometry in one- to ten-years-old diazepam injections. The content of diazepam was within the specifications in all the samples. Not more than 1.5% degradation of diazepam was found after ten years.

Xanthine and hypoxanthine in amniotic fluid during pregnancy.

Xanthine and hypoxanthine are indicators of cellular hypoxia. The purpose of our study was to establish a reference range for the concentrations of xanthine and hypoxanthine in amniotic fluid. Of a total of 38 included in the investigation, 27 pregnant women were found to have low values for xanthine (less than 1.2 mumol/l) and hypoxanthine (less than 0.4 mumol/l). To our knowledge, this is the first attempt to define a reference range for xanthine and hypoxanthine concentration in amniotic fluid during pregnancy.

Gardnerella vaginalis in posthysterectomy infection.

Eighty-six women were admitted for abdominal hysterectomy. Preoperatively, 43 women were culture-positive for Gardnerella vaginalis from the cervical os, and 43 women were culture-negative. Postoperatively, 18 patients developed inflammation; among those 14 patients from the culture-positive group were infected, whereas only 4 patients from the culture-negative group developed inflammation. The difference between occurrence of G. vaginalis and the absence of the bacteria in patients with postoperative infection is highly significant. No such increased risk of postoperative infection was correlated to the isolation of any other microorganism looked for viz. aerobic and anaerobic bacteria, yeasts, viruses or chlamydiae. G. vaginalis may play a causative role in the development of posthysterectomy infection.

[Demonstration of urogenital Chlamydia infection by means of the Chlamydiazyme test]. / Påvisning af urogenital Chlamydia-infektion ved hjaelp af Chlamydiazyme-testen.

Abbott's recently introduced Chlamydiazyme test which is based on the Elisa principal and cell culture technique was employed with the object of demonstrating urogenital infection with Chlamydia trachomatis in 150 persons. Neither of the methods were optimal. The Chlamydiazyme test had a lower sensitivity and specificity than the cell culture method.

Isolation of Gardnerella vaginalis in pure culture from the uterine cavity of patients with irregular bleedings.

Hysterectomy was performed in three patients because of persistent irregular vaginal bleeding. Before the operation samples were taken from the cervical os for cultivation of Gardnerella vaginalis, yeasts, viruses, Chlamydia trachomatis, and aerobic and anaerobic bacteria. Immediately after the operation, the uterus was opened under sterile conditions and samples obtained from the isthmus and fundus of the uterine cavity were examined microbiologically. In all three patients G. vaginalis was grown in pure culture from the fundus. Serum antibody titres against G. vaginalis were significantly raised in all three patients, and histology revealed mononuclear cells in the endometrium. The isolation of G. vaginalis from the endometrium of patients with clinical and histological signs of inflammation and with antibodies to G. vaginalis in serum indicates that the organism may play a causative role in endometritis.

The effect of oxytocin injection into the umbilical vein for the management of the retained placenta.

In a single-blind study 51 patients with retention of the placenta were randomized into one of three groups: Group 1 was given 10 IU of oxytocin in 10 ml of sodium chloride into the umbilical vein; group 2 was given 10 ml of sodium chloride; group 3 was treated with manual removal of the placenta. No significant differences were recorded in groups 1 and 2, and no advantages were found in comparison with the procedure normally used.

Intra-uterine fetal death and thrombosis of the umbilical vessels.

Intra-uterine fetal death associated with thrombosis of the umbilical cord vessels is a rarely described condition. Three cases are now reported and the possible genesis of the thrombosis is discussed, with particular regard to the significance of disturbances in the fetal circulation.

Transcutaneous PO2 monitoring in routine observation of newborns.

TcPO2 was monitored in 209 of 814 infants admitted to the premature ward connected to our obstetric department. The majority of the infants were monitored less than 14 h. Approximately 77% of the infants were treated with up to 40% O2, while for a period the remaining infants were treated with more than 40% O2. TcPO2 values were generally controlled to the desirable range of 7-12 kPa (50-90 mm Hg). The daily handling of the equipment was performed by the nursing staff, who found good correlation between the TcPO2 measurement and clinical observations. The importance of application of the electrode in the preductal area is stressed to avoid hyperoxemia in the retinal vessels.