Traumatic pseudoaneurysm of the superficial temporal artery associated with facial nerve palsy.

Aneurysms of the superficial temporal artery as a result of trauma occur rarely. These pseudoaneurysms tend to present 2 to 6 weeks following initial injury with a painless swelling which may be associated with a headache, ear discomfort or other vague symptoms. Neurological complications are very rare. A thorough history and physical examination are essential. Investigations such as duplex scanning, angiography or CT scanning may be helpful in difficult cases. The most common treatment is surgical. Embolization may prove to be an alternative to surgery in some cases. We review a rare case of superficial temporal artery aneurysm associated with a facial nerve palsy which was treated surgically. A thorough review of the literature is presented.

An assessment of tonometry and regional splanchnic blood flow during aortic cross-clamping in the pig.

We aimed to evaluate the tonometer in the assessment of gastrointestinal ischaemia induced by an infrarenal aortic cross-clamp. Nine anaesthetized pigs were cannulated for haemodynamic monitoring and radionuclide labelled microsphere (RLM) injection. Gastric and sigmoid tonometers were positioned. After haemodynamic stabilization an infrarenal aortic cross-clamp was applied. Animals were sacrificed at the completion of the study and tissue sampled from the stomach and sigmoid colon for regional blood flow measurements. Measurements were made pre-clamp, post-clamp, pre-release and post-release. Haemodynamic parameters, gastric intramucosal pH (pHi) and blood flow did not change throughout the experiment. Arterial pH increased during cross-clamp and returned to baseline post-release. Arterial bicarbonate fell post release. Sigmoid blood flow fell during cross-clamp. The sigmoid pHi fall, delayed until pre-release, remained low post-release. Although there was a consistent fall in sigmoid pHi, 63% of post-clamp values remained within the baseline range. We conclude that maintaining haemodynamic parameters around baseline values resulted in maintenance of gastric mucosal perfusion as indicated by a steady gastric pHi. However, below the aortic cross-clamp, delay between change in sigmoid colon blood flow and change in pHi and wide variation in sigmoid pHi limits the value of an individual pHi measurement in detecting ischaemia.

Sigmoid and gastric tonometry during infrarenal aortic aneurysm repair.

BACKGROUND: The value of the sigmoid tonometer in predicting sigmoid ischaemia and postoperative enteric organism infection has been reported but the value of tonometric measurement has been challenged. The purpose of this study was to examine the use of tonometric measurements in a series of patients undergoing infrarenal aortic aneurysm repair. METHODS: We assessed the results obtained when sigmoid (n=11) and gastric (n=8) tonometry were performed in patients undergoing infrarenal aortic aneurysm repair (n=11). We measured blood flow ultrasonically (n=6) in the inferior mesenteric artery(IMA) and IMA stump pressures. Sigmoid and gastric tonometry were measured prior to clamping of the infrarenal aorta, during cross clamping and after clamp release at 1, 4, 16 and 20h. Ultrasonic flow was measured before clamping. Stump pressures in the IMA were measured before, during and after clamping. RESULTS: The IMA was chronically occluded in five patients. The IMA flow was 37.5 +/- 8.7 mL/min (mean +/- s.e.). The mean IMA stump pressures before, during and after clamping were 64 +/- 13, 48 +/- 8 and 69 +/- 10 mmHg, respectively, and did not differ significantly. Mean systematic arterial pressures at these times were 89 +/- 7, 95 +/- 5 and 86 +/- 8 mmHg. These did not differ significantly or when compared with IMA stump pressure. The gradient between systemic arterial pressure and IMA stump pressure did not vary significantly at any of these times. Sigmoid and gastric intramucosal pH (pHi) did not differ significantly at any of the above times. Both sigmoid gastric pHi dropped on clamp application but 4 h afterwards had returned to baseline levels. Systemic arterial pH reflected significant ischaemia during clamping and shortly after release of the clamp(P=0.008). CONCLUSIONS: Tonometry may reflect systemic events as much as regional ischaemia. Useful tonometry results may depend on the development of a trend rather that individual measurements. The routine use of tonometry to detect intestinal ischaemia may not be cost-effective in aortic surgery.

Is laparoscopy associated with a lower rate of postoperative adhesions than laparotomy? A comparative study in the rabbit.

This trial set out to test the hypothesis that there is no difference in the incidence of intra-abdominal adhesions after a stereotyped intraperitoneal injury created via laparoscopy or laparotomy. Twenty New Zealand White rabbits had a 2 x 2 cm area of peritoneum stripped off their caecum and adjacent parietal peritoneum, either by laparotomy or laparoscopy. Outcome was assessed by the incidence of adhesions to the test site and the wound. There was no difference in the rate of adhesions at the test site in the two groups. The rate of adhesions to the wound was different in the two groups (70% laparotomy, 0% laparoscopy; P = 0.003). In a rabbit model, comparing laparoscopy and laparotomy in a strictly controlled operative environment, a stereotyped intraperitoneal injury results in similar rates of postoperative adhesions. Laparoscopy is, however, associated with a much lower incidence of wound adhesion. The potential for postoperative adhesions is real after laparoscopic surgery.

The effect of infrarenal aortic cross clamping and declamping on renal function in the pig.

Renal insufficiency following periods of infrarenal aortic cross clamping has been reported by some investigators but not by others, and conflicting views have been expressed concerning the ability of renal autoregulation to overcome the adverse circulatory effects of cross clamping. The object of this study was to examine the blood flow distribution to four layers within the renal cortex (subcapsular to juxtamedullary) and measure global renal function following application and release of an aortic cross clamp after 90 min. Nine juvenile female pigs weighing 25 to 50 kg were anaesthetized and subjected to intensive physiological monitoring. Throughout the study the blood pressure and cardiac output were maintained as close as possible to control levels by fluid administration and varying the depth of anaesthesia. Renal cortical blood flow was estimated by means of radionuclide labelled microspheres and global renal function was determined by the measurement of creatinine clearance. The aortic cross clamp was applied for 90 min immediately distal to the renal arteries and proximal to the inferior mesenteric artery. Cardiovascular and renal parameters were recorded on four occasions during each experiment, prior to, 10 and 60 min after cross clamping, and 30 min after clamp release. No significant changes in cardiac output, systemic blood pressure of global renal function were recorded during the study. There was, however, a significant fall in renal blood flow following release of the aortic cross clamp but this was not associated with any significant redistribution of blood flow within the renal cortex. In the pigs studied, the application of an infrarenal aortic cross clamp did not have any adverse effects on the cardiovascular system or on global renal function.(ABSTRACT TRUNCATED AT 250 WORDS)

Incidence of rupture of aortic aneurysms after coincidental operation.

The clinical course of 76 patients with aortic aneurysmal disease undergoing 107 coincidental surgical procedures was analysed in order to examine the relationship between aortic aneurysmal rupture and coincidental treatment. Additionally the incidence of aneurysmal rupture was assessed following 82 endoscopic procedures in 42 patients with aortic aneurysms. Two patients ruptured an aortic aneurysm after operation, one after colonoscopy (maximal transverse diameter 7 cm) and one after coronary artery bypass grafting (maximal transverse diameter 5.6 cm). The mean maximal transverse diameter of aneurysms in 76 patients was 5.08 cm (95% confidence interval 4.7-5.4 cm). Both patients with ruptured aortic aneurysm were outside these confidence limits and were known hypertensives whose perioperative control of hypertension was questionable. The present series of patients is discussed with reference to induction of collagenase activity as a precipitating cause for postoperative rupture of aortic aneurysms, perioperative control of hypertension, transverse aneurysm diameter as a predictor of postoperative rupture and conduct of coincidental procedures in the presence of aneurysmal disease.

Duplex scan surveillance of infrainguinal prosthetic bypass grafts.

PURPOSE: Surveillance protocols of infrainguinal vein bypass grafts have almost universal acceptance. To date corresponding studies of prosthetic grafts have not been carried out. We have performed a prospective 4-year duplex scan follow-up on polytetrafluoroethylene grafts to assess the usefulness of a surveillance program of prosthetic bypass grafts in preventing graft failure. METHODS: Over 4 years 69 infrainguinal polytetrafluoroethylene grafts in 56 patients were studied at six monthly intervals by our vascular laboratory. Full duplex scan mapping of the grafts and inflow and outflow arteries and standard ankle pressure measurements were performed. A midgraft peak flow velocity was also measured. RESULTS: Over 4 years 27 (39.1%) grafts occluded without any predictive changes in the preceding duplex scan examination. Of the 42 (60.9%) grafts that remained patent, only four developed stenoses (three at the proximal anastomosis and one at the distal anastomosis) that were amenable to intervention. Changes in ankle pressures or midgraft flow velocity did not predict failure. CONCLUSIONS: The low yield of remediable disease does not justify the cost of duplex scan surveillance of infrainguinal prosthetic bypass grafts.

Venous stasis during laparoscopic cholecystectomy.

The objectives of this research were (a) to determine the effect of insufflation at laparoscopic cholecystectomy to 12 mm Hg on femoral venous blood flow; and (b) to assess the function of intermittent pneumatic compressors (IPC) and intermittent electric calf stimulators (IECS) in the presence of a pneumoperitoneum. Measures of baseline venous blood flow velocity, femoral vein diameter, and maximum blood flow velocity achieved by IPC or IECS were made in the presence or absence of a pneumoperitoneum of 12 mm Hg. The ICP and IECS were randomly allocated to either leg. All measures were made by an experienced sonologist. Insufflation to 12 mm Hg caused a statically significant decrease in femoral blood flow velocity and was accompanied by a significant increase in femoral vein diameter. The IPC and IECS were able to achieve pulsatile venous blood flow despite the presence of a pneumoperitoneum, but they had no effect on the depressed baseline blood flow velocity. We concluded that insufflation to 12 mm Hg causes significant venous stasis in the lower limb and that IPC and IECS cannot completely eliminate this stasis. Further research needs to be done to clarify the optimal methods of prophylaxis in view of the implications for deep venous thrombosis.

Lower limb venous hemodynamics during laparoscopy: an animal study.

To assess the impact of raised intra-abdominal pressure associated with laparoscopy on venous return, we have used an animal model (pig) to study the effect of progressive increases in insufflation pressure on femoral venous blood outflow. As a second variable, the effect on flow of the reverse Trendelenburg position was also assessed. Evidence of any adaptation in venous blood flow to the increased intra-abdominal pressure was assessed during a prolonged surgical procedure. These studies have shown that femoral venous blood outflow in the pig is markedly depressed at insufflation pressures of 10 to 20 mm Hg. The reverse Trendelenburg position accentuates this reduction in flow, and there was no sign of adaptation to this depressed flow during a laparoscopic Nissen fundoplication. These findings have clear implications for the potential of deep venous thrombosis/pulmonary embolism (DVT/PE) following prolonged therapeutic laparoscopy.

Azithromycin clinical pharmacokinetics.

Azalide antibiotics, of which azithromycin is the first demonstrated, have different pharmacokinetics from other antibiotics currently used. The bioavailability of the drug is approximately 37%. Extensive and rapid distribution from serum into the intracellular compartments is followed by rapid distribution to the tissues. Tissue concentrations exceed serum concentrations by up to 100-fold following a single azithromycin 500mg dose. Concentration of the drug within phagocytes aids in its ability to combat infections. High concentrations of azithromycin are found in the tonsil, lung, prostate, lymph nodes and liver, with only small concentrations found in fat and muscle. A 500mg dose on day 1, followed by 250mg daily on days 2 to 5, has been demonstrated to maintain azithromycin concentrations at sites of infection and continues to be effective for several days after administration has ceased. The pharmacokinetics of azithromycin make it a drug with diverse therapeutic applications.