A Unique Model for ONSD Part II: Inter/Intra-operator Variability.

OBJECTIVE: To evauluate our novel ultrasound model for measurement of optic nerve sheath diameter (ONSD) and determine the intra- and inter-operator variability associated with this technique. METHODS: We conducted ten measurements of ONSD per model amongst eight different models with a single experienced operator to examine intra-operator variability. Similarly, we had seven different operators measure the OSND twice in eight different models, in order to determine inter-operator variability analyzed with a three level linear statistical model. RESULTS: For intra-operator variability, the intra-cluster correlation coefficients for the experienced and novice operators were 0.643 and 0.453 respectively. This displayed improvement in intra-operator variability with experience. The inter-cluster correlation coefficient was 0 for the group of novice operators, indicating negligible difference amongst multiple operators in measuring any given model of ONSD. A strong, statistically significant, linear relationship between the actual model disc size and the ultrasound ONSD measures was identified, implying the reliability of the images produced by our novel model. CONCLUSIONS: Utilizing a novel model for ONSD ultrasonography, we have determined the intraoperator reliability of ONSD measurement to be moderate, with no appreciable difference amongst multiple operators. Improvement in measurement reliability has been demonstrated between expert and novice operators with our model, indicating the potential benefit of simulation platforms for teaching the technique of ONSD ultrasound.

Factors increasing the mortality rate for patients with ruptured abdominal aortic aneurysms.

The objective of this report was to analyze the current surgical results of operative treatment in patients suffering ruptured AAA (abdominal aortic aneurysms) and to define those independent predictive factors for mortality. During a period of 2 years, from January 1996 to December 1997, 144 patients operated on for ruptured AAA in 10 hospitals were included in a multicenter retrospective study. Among the collected variables concerning each patient, those with potential relation to surgical mortality were studied: gender, age, diabetes, hypertension, cardiopathy, pulmonary obstructive disease, preoperative renal dysfunction, symptomatic cerebrovascular disease, peripheral vascular disease, hematocrit on admission, preoperative hypotension < 80 mmHg, loss of consciousness, cardiac arrest, aortic aneurysm location (infrarenal versus non-infrarenal), iliac involvement, aneurysm size, type of rupture, left renal vein ligature, ligature of a patent inferior mesenteric artery, place of aortic cross-clamping, type of grafting, exclusion of both hypogastric arteries, venous technical complications, associated surgery, use of cell saver, intraoperative blood loss, and postoperative complications (renal failure, sepsis, coagulopathy, cardiac complications, pulmonary complications, colon ischemia, prosthetic graft complications, and need for reoperation). Those variables with statistical significance in the univariate analysis were introduced into a multivariate logistic regression model to determine the independent predictors of death. From our results we concluded that surgery for ruptured abdominal aortic aneurysms continues to have an excessively high mortality rate. Even though some preoperative variables could be identified as predictors of mortality, an absolute mortality risk has not yet been determined and the decision to negate surgery should be individualized rather than taken on that basis only. Early diagnosis and treatment of symptomatic aneurysms would improve mortality figures and selective screening should be contemplated.

The prevalence of otitis media with effusion among Inuit children.

PURPOSE: Studies over the past 30 years have shown a decline in the prevalence of chronic otitis media in some parts of the Arctic, presumably largely due to more prompt treatment, preventing acute infections from becoming chronic. In contrast, some researchers have suggested that the prevalence of otitis media with effusion has increased. The purpose of this study was to determine the prevalence of otitis media with effusion among children aged 6-17 years in Sanikiluaq, an Inuit community in the Keewatin District of the Northwest Territories. METHODS: A cohort of 126 children at the local community school was examined and assessed by otoscopy, audiometry, and impedance testing. RESULTS: Four percent of children were found to have otitis media with effusion causing significant hearing loss. An additional 17% had otitis media with effusion, with minimal or no detectable hearing loss. Thus, the prevalence of otitis media with effusion in Sanikiluaq school-age children is 4% to 21%. There are few previously published data with which to compare these findings. In the past, otitis media with effusion was infrequently reported among the Inuit. Therefore, our results may suggest an increasing prevalence over the past several decades. If these results are representative of other communities, otitis media with effusion is a significant health problem among the Inuit.

Intraoperative hemodilution during elective vascular reconstruction.

Intraoperative hemodilution and retransfusion were used for blood replacement in 30 patients who underwent elective reconstruction of the abdominal aorta, thoracic aorta or femoropopliteal segment. During each operation, 1,000 to 2,000 milliliters of autologous blood were collected through an arterial cannula during induction of anesthesia and the initial stages of operative exposure. Each volume of shed blood was replaced with 1.5 volumes of colloid and crystalloid solutions to maintain a stable intravascular volume despite transient low hematocrit values--mean, 25.8 +/- 2.1 per cent--during the period of maximum blood loss in the surgical field. Collected blood was stored in standard citrate-phosphate-dextrose disposable units and was reinfused at the conclusion of the vascular procedure. Swan-Ganz pulmonary artery catheters were inserted in an initial study group of 15 patients. Serial blood hematocrit and coagulation studies and hemodynamic parameters were measured or calculated before and after induction of anesthesia, during hemodilution, after reinfusion of autologous blood and 24 hours after operation. Improvement in cardiac output and reduction in peripheral vascular resistance maintained adequate systemic oxygen transport during hemodilution. Transient dilution of coagulation factors was documented by abnormal prothrombin and partial thromboplastin times, but serious bleeding tendencies did not occur. Twenty-one of the 30 patients received no homologous blood. Considering the entire series of 30 patients, each required only 0.46 +/- 0.87, S.D., unit of homologous blood during operation and the postoperative period.

Thrombosis in a cavernous left-sided inferior vena cava. An unusual abdominal mass.

A 19-year-old man had an abdominal mass and swelling of the left thigh. The presumptive diagnosis was lymphoma. On exploration the mass proved to be a thrombosed multiloculated "cavernous transformation" of a venous structure, presumably the inferior vena cava, which on postoperative cavogram was shown to be otherwise absent. The venous system of the left lower extremity showed phlebographic evidence of old thrombosis, but that of the right lower extremity was normal. The patient did well without further treatment, despite some residual swelling of the left thigh. To our knowledge, this precise combination of inferior vena cava anomalies has not been encountered before; certainly not presenting as a mass.