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Biomedical subjects

P N Larsen

Publications and source records attributed to P N Larsen.

14 recordsLinked to original sources
PubMed1991

Gastric and colonic oxygen tension measured with a vacuum-fixed oxygen electrode.

A new electrode system for determination of visceral oxygen tension is presented. The system consists of a transcutaneous oxygen electrode (E5242 Radiometer A/S. Copenhagen), which is screwed into a suction ring and fixed to the organ by applying a vacuum. The electrode membrane is then in contact with the organ surface via a fluid layer with a thickness of a few micrometres, without interference from atmospheric air and without mechanical disturbance of the membrane. The electrode system was tested on the gastric and colonic wall in six pigs. As reference, a silicone tonometer was placed subserously beneath the vacuum-fixed electrode. The silicone tonometer was connected to a second transcutaneous oxygen electrode. The tissue oxygen tension was changed by subjecting the animals to various inspiratory concentrations of oxygen and to hypovolaemia. The oxygen tension measured by the vacuum-fixed electrode (PO2vac) was compared with the oxygen tension measured by the tonometer (PO2tono). A good correlation was demonstrated between PO2vac and PO2tono, the correlation coefficient being 0.8619, confirming that the suction-fixed oxygen electrode measures tissue oxygen. The lowest possible vacuum to hold the electrode unit in place was between 4.0 and 6.7 kPa. Provided the measuring time did not exceed 3 min. vacuum had only slight influence on the measured oxygen values. The mean change in PO2vac induced by varying the vacuum from 7 to 26 kPa, and 26 to 7 kPa, was only +0.23 kPa (-1.2 to +1.9) and +0.19 kPa (-0.3 to +1.3), respectively. The mean stabilization time, defined as the time from electrode application until achieving 95% of the equilibration value, was 66 sec (SEM, 3.4 sec) and 57 sec (SEM, 3.0 sec) on the gastric and colonic wall, respectively. The measured values of PO2vac varied significantly between different areas on the gastric wall (p less than 0.001). When several surface measurements were performed throughout the investigated area, the mean oxygen tension approached the oxygen tension measured by the tonometer. It is concluded that the vacuum-fixed electrode constitutes a reliable, easy and, noninvasive method for measurements of the oxygen tension in the gastric and colonic tissue.

Animals↗
PubMed1991

Ceftriaxone vs. ampicillin + metronidazole as prophylaxis against infections after clean-contaminated abdominal surgery.

In a prospective, controlled, double-blind study, 496 patients undergoing abdominal surgery were given antibiotic prophylaxis with a single dose of either ceftriaxone or ampicillin + metronidazole. No significant intergroup difference was found between the respective overall rates of infectious complications (3.2% and 4.9%). Analysis of the microbiologic findings showed incisional wound infections, mainly caused by gram-negative rods, to be more common in the ampicillin-metronidazole group, whereas deep wound infections were more frequent in the ceftriaxone group. It is concluded that ceftriaxone seems to be more efficient than ampicillin-metronidazole as prophylaxis against incisional wound infection, but should preferably be supplemented with an antianaerobic agent to prevent deep wound infections.

Abdomen↗
PubMed1990

Continuous assessment of oxygen saturation and subcutaneous oxygen tension after abdominal operations.

Ten patients undergoing abdominal operations had oxygen saturation (SpO2) and transcutaneous (PtcO2) and subcutaneous (PscO2) oxygen tensions monitored continuously during the second and third postoperative nights from 11 pm to 7 am. At the end of the second postoperative night an oxygen stimulation test (10 l/min by face mask) was carried out in eight of the 10. Median SpO2 was 91% (range 82-95) on the second, and 91% (86-95) on the third, postoperative nights, respectively. Six patients had intermittent episodes of desaturation to less than 80%, each of less than one minute's duration. PtcO2, but not PscO2, followed the episodic variations in SpO2. PscO2 was 58 mmHg (46-69) on the second postoperative night and 61 mmHg (48-71) on the third postoperative night. PscO2 correlated with SpO2 in all but one patient who had lower PscO2 than expected from the measured SpO2 and estimated PaO2. Oxygen treatment increased individual PscO2 by 14 mmHg (9-49), PtcO2 by 38 mmHg (10-104), and SpO2 to 99% (95-100), but stable PscO2 was not achieved within the 20 minute period of treatment. These results obtained during continuous measurements show pronounced intersubject differences in oxygen tensions near the surgical wound in the late postoperative period. The results suggest that pulmonary oxygenation is the most important determinant of mean subcutaneous oxygen tension after uncomplicated elective abdominal operations.

Abdomen↗
PubMed1989

Intraincisional antibiotic in addition to systemic antibiotic treatment fails to reduce wound infection rates in contaminated abdominal surgery. A controlled clinical trial.

One hundred ninety patients with peritonitis at the time of abdominal surgery were allocated at random to systemic antibiotic treatment alone or systemic antibiotic treatment combined with topical application of antibiotics in the wound at the time of wound closure. The overall wound infection rate was 17 percent without significant difference between the two treatment groups (P greater than 0.80).

Abdomen↗
PubMed1989

Characterization of the silicone tonometer using a membrane-covered transcutaneous electrode.

A new oxygen tonometry system consisting of a silicone tube, highly permeable to O2 and CO2 is described. The silicone tube was connected to a membrane-covered transcutaneous oxygen electrode (E5242 Radiometer A/S, Copenhagen, Denmark) via an airtight polycarbonate chamber, and flushed with isotonic saline equilibrated with atmospheric air. The present tonometer system offers certain advantages compared with other systems: continuous reading, minimal oxygen consumption, furthermore the system is thermostated and is insensitive to movement. The tonometry system was tested in vitro for characterization of a silicone tube (Coroplast, Fritz Müller KG, Wuppertal, FRG) 1.0 mm in inner diameter and 1.5 mm in outer diameter. The experiments showed that the oxygen tension measured at the electrode after passage of the tonometer approached the oxygen tension outside the tonometer when the length of the tonometer was increased and when the flushing rate of saline through the tonometer was decreased. The time taken for the flushing solution to reach an equilibrium with the oxygen tension outside the tonometer increased with increasing tonometer length, and decreased with increasing flushing rate. Changing the difference between oxygen partial pressure in the flushing solution and the oxygen partial pressure outside the tonometer tube did not influence the relative equilibration value and the equilibration time. When a pO2 value is measured by the electrode, the exact oxygen tension outside the tonometer tube, for every given length of the tonometer and flushing rate through the tonometer can be read from our calibration curves.

Blood Gas Monitoring, Transcutaneous↗
PubMed1989

Closure of the abdominal fascia after clean and clean-contaminated laparotomy.

This prospective, randomized study compares continuous absorbable suture (Dexon), continuous nonabsorbable suture (Surgilon) and interrupted absorbable suture (Dexon) for fascial closure of clean and clean-contaminated laparotomy wounds. Three months postoperatively, the overall frequencies were for wound dehiscence 0% (0/238), wound infection 5.5% (13/238), hernia formation 0.4% (1/238) and sinus formation 0% (0/238). After a median period of 41 months (range 14-59 months) a physical examination was performed in 93.7% (224/238) of the patients and the observed overall frequency of hernia was 3.1% (7/224). No difference was detected in incidence of wound complications when comparing the three groups. We conclude that layered closure of a laparotomy wound is safe whether using nonabsorbable or absorbable sutures and whether applying a continuous or interrupted technique in the fascial closure of clean and clean-contaminated wounds.

Abdominal Muscles↗
PubMed1988

Clinical versus ultrasonographic evaluation of scrotal disorders.

Clinical and ultrasonographic examinations of scrotal disorders were compared in 166 patients in order to determine their ability to distinguish between those diseases requiring surgery and those requiring clinical follow-up only. Ultrasound examinations were efficient in discriminating between normal and pathological findings. Extra-testicular lesions were readily differentiated from testicular ones. Although both clinical and ultrasonographic examinations had high sensitivity (90%) in detecting testicular cancer, the number of false positive findings was smaller after ultrasound examination. This gave a predictive value of a positive test of 53% after ultrasound examination but only 33% after clinical examination. Ultrasound examination may, therefore, reduce the number of surgical explorations in the scrotum and should be performed in patients with suspected testicular pathology based on history and palpatory findings.

Adolescent↗
PubMed1986

Treatment of abscesses in the vulva. Conventional open treatment versus primary suture under antibiotic cover.

Seventy patients were treated for a subcutaneous abscess in the vulva. In 35 consecutive patients the abscess was treated conventionally with deroofing of the abscess and wet dressings. In the other 35 consecutive patients the abscess was treated by incision, curettage and primary suture under antibiotic cover with a single dose of clindamycin. In the conventionally treated group the median stay in hospital was 7 days and the median healing time 18 days. In the group treated by primary suture the median stay in hospital was 2 days and the median healing time 7 days (P less than 0.0001). Recurrence of abscess was observed in one patient in each group. No other complications were observed in either group. It is concluded that vulvar abscesses may be treated safely and advantageously by primary suture under antibiotic cover.

Abscess↗
PubMedDate not supplied

Ceftriaxone/metronidazole is more effective than ampicillin/netilmicin/metronidazole in the treatment of bacterial peritonitis.

In a prospective, open, controlled clinical study, 190 consecutive patients who were thought to have bacterial peritonitis before operation, were randomised to antibiotic treatment during and after operation with either ceftriaxone 1 g plus metronidazole 1.5 g once daily (n = 94) or ampicillin 2 g plus netilmicin 150 mg twice daily plus metronidazole 1.5 g once daily (n = 96). Incisional and deep surgical wound infections, postoperative pneumonia and urinary tract infection as well as deaths caused by infection were recorded. Ceftriaxone-metronidazole was significantly more effective than ampicillin-netilmicin-metronidazole, 6/94 wound related infections (6%) compared to 18/96 (19%) (p = 0.02). In patients with peritonitis caused by a perforated colon or appendix the rates of clinical failure were 6% and 28%, respectively. We consider ceftriaxone plus metronidazole an efficient and easily administered antibiotic regimen in patients with bacterial peritonitis, and both the wide range of activity against Gram-negative aerobic rods and the long half life of ceftriaxone seem to be beneficial.

Adolescent↗