Is the IV obstructed or infiltrated? A simple clinical test

Objective. The objective of our study was to determine if clinical observation of pressure-flow relationships (PFR) can differentiate between partial external obstruction (obstruction) and infiltration as a cause of poor performance of gravity-fed infusions.Methods. A total of 24 patients with functional intravenous cannulae in situ had obstruction simulated by the application of a tourniquet proximal to the cannula. The change in flow (F) for a discrete change in pressure (P) was determined in each case by counting drop rates at two different elevations of the fluid reservoir level, 10 cm apart. The same process was repeated in 15 patients in whom the cannula was in an extra vascular location (infiltration). Three sizes of cannula—16-gauge, 18-gauge, and 20-gauge—were examined, with equal distribution of sizes in each group. The effect on flow rates of inflating a blood pressure (BP) cuff proximally on the cannulated limb was assessed. The ratio P/F is the total resistance of the infusion system, and by subtracting known values for resistance of infusion tubing and cannula, the venous or tissue resistance was calculated.Results. There was a statistically significant difference between the change in flow for obstructed compared with infiltrated cannulae for the same change in pressure for each cannula size. The mean venous resistance was 23 mm Hg/L/hr, while that of tissue was 280 mm Hg/L/hr, with no overlap between groups. There was no effect on flow rate with blood pressure cuff inflation in the infiltrated group whereas flow progressively fell in the obstructed group.Conclusions. Clinical observation of PFRs in poorly functioning gravity-fed IV infusions can assist in detecting infiltration as a cause. Inflation of a blood pressure cuff will further impair flow where the cannula is intravascular, but will have no effect in an extravascular location.     

Traumatic rupture of the thoracic aorta: Should one always operate immediately?

Although the traditional therapy for blunt traumatic rupture of the thoracic aorta (TRA) is immediate operative repair, there may be a selective role for delayed repair, particularly in patients with head trauma, respiratory failure, or cardiac dysfunction. The present study examines the hypothesis that TRA can be managed by selective delayed operative repair. Clinical data were collected from 59 consecutive patients with TRA at a regional trauma unit. All TRAs were at the aortic isthmus. Patients were retrospectively classified into three groups: group I (n=12) included patients who either arrived in extremis or rapidly became unstable during triage; group II (n=3) included patients who had no contraindications to early repair and underwent repair at the time of diagnosis; and group III (n=44) consisted of patients who because of concomitant injuries or sepsis required initial admission and management in the intensive care unit until their clinical status had improved sufficiently to allow for deliberate delayed operative repair of the TRA. The delay ranged from 1 day to 7 months. Eight patients have yet to undergo repair and remain well at follow-up from 1 to 4 years. Overall survival rates in groups I, II, and III were 17%, 100%, and 82%, respectively. The surgery-related mortality rate in group III was 10% (three patients). Only two (4.5%) patients in group III died as a result of a ruptured aorta within 72 hours of admission. In conclusion, contrary to surgical doctrine, TRA may not require immediate operative repair in all cases, but may instead be managed selectively depending on the patient's clinical status.     

‘Hybrid’ Bariatric Surgery: Bilio-pancreatic Diversion and Duodenal Switch - Preliminary Experience

Background: Hybrid, combined or mixed bariatric surgery is the combination of a degree of ‘malabsorption’ (as achieved by the intestinal bypass) with a ‘rrestriction’ (as achieved by gastric bypass or gastroplasty), thereby simultaneously reducing the absorption of fats in the small bowel and decreasing the intake of food. Methods: A modification of the bilio-pancreatic diversion (BPD) with a duodenal switch procedure, vertical lineal gastrectomy and preservation of the pylorus, has been used in 23 patients. The antropyloric pump and 4 cm of the duodenum are left intact to preserve physiologic gastric emptying and to prevent anastomotic ulcer. The use of staplers and continuous running sutures reduces surgical risks and operative time. Results: One patient, converted from a vertical gastroplasty, had an intrathoracic esophageal perforation and died of multisystemic organ failure, a mortality rate of 4.5%. One patient had a partial dehiscence of the laparotomy wound. Three patients developed subcutaneous seromas. Mean weight losses during the first 4 months were 13, 11, 6 and 5 kg, with a loss of 70% of excess weight in patients approaching 1 year. No patient needs treatment for diarrhea. No serious secondary side-effects have been detected. Conclusion: This operation appears to result in very satisfactory weight loss, improved quality of life, and a low incidence of complications.     

The Effect of Basic Fibroblast Growth Factor on the Reversion of Omental Adipocytes from Lean and Obese Patients

Background: this study was designed to characterize some of the biochemical and molecular genetic changes during reversion of human fat cells. Methods: mature adipocytes were isolated from greater omental fat tissue of eight lean and 14 massively obese persons by established methodology. Results: at day 7 of adherence to Leighton tubes, there was appreciable depletion of triacylglycerol, as well as assumption of an elongated contour. Relatedly, there was an increase in the expression of β-actin mRNA and a significant decrease in the specific activity of cytosolic glycerophosphate dehydrogenase. The decrement in the specific activity of glycerophosphate dehydrogenase, after 7 days in culture, was significant at p < 0.001. Basic fibroblast growth factor at 10 ngml^-1 accelerated significantly (p < 0.03) the decrease in the specific activity of glycerophosphate dehydrogenase in adipose cells from lean subjects. In contrast, basic fibroblast growth factor had no significant influence on cells from massively obese persons. Conclusion: such resistance may contribute to the intractability of massive obesity.     

Comparison of the polyvinyl alcohol sponge and expanded polytetrafluoroethylene subcutaneous implants as models to evaluate wound healing potential in human beings

Our current understanding of the complex processes involved in wound healing is based mainly on studies of animal models. Although this information has been useful, it may not totally reflect the response found in human beings. For example, human beings have a tendency to either "overheal," as seen in keloids and hypertrophic scar formation, or have deficient healing, as seen in chronic ulcer formation. No animal models are available to analyze these human clinical pathologic conditions. Therefore the objective of this study was to analyze the wound healing response in a large population (n = 40) of normal healthy human beings as a first step to begin studies of abnormal human wound healing. Simultaneously, a comparison was made between the polyvinyl alcohol implant and the expanded polytetrafluoroethylene implant model. Under sterile conditions with the use of local anesthesia, two preweighed polyvinyl alcohol implants and two standard 6 cm expanded polytetrafluoroethylene implants were placed subcutaneously in the upper arm of each subject. High-performance liquid chromatography was used to quantitate isoleucine and hydroxy-l-proline in acid hydrolysates of each implant. Isoleucine was used as an indicator of protein content in the tissue sample, whereas hydroxyproline reflected collagen content. No infectious or hemorrhagic complications were found in the 40 volunteers included in the study. No significant difference was found in isoleucine or hydroxy-l-proline content between postoperative day 7 polyvinyl alcohol implants and day 14 polyvinyl alcohol implants. In contrast, both isoleucine and hydroxy-l-proline content were significantly increased in day 14 expanded polytetrafluoroethylene implants compared with day 7 implants (p < 0.005 and p < 0.001, respectively). In addition, the ratio of hydroxy-l-proline to isoleucine was significantly increased in day 14 expanded polytetrafluoroethylene implants compared with day 7 expanded polytetrafluoroethylene and both day 7 and day 14 polyvinyl alcohol implants (p < 0.001). This observation suggests that by 14 days implantation of expanded polytetrafluoroethylene stimulated an increased deposition of collagen. No significant differences were found in the hydroxy-l-proline to isoleucine ratios among day 7 expanded polytetrafluoroethylene, day 7 polyvinyl alcohol, and day 14 polyvinyl alcohol implants. Histologic analyses correlated with the biochemical findings. These results suggest that expanded polytetrafluoroethylene may be the preferred implant for studies designed to examine pathologic processes associated with retarded wound healing. In contrast, the polyvinyl alcohol implant may be better suited for studies where a low background response is required. Moreover, the extreme variability in normal healthy volunteers seen in this study correlates clinically with the finding that, among the normal adult human population, there is a heterogeneous wound healing response.     

Improved survival in young women with breast cancer

Background: Young age has been hypothesized to be an adverse prognostic factor for women with breast cancer. This association, based on historical data, may not reflect recent advances in breast cancer management. Methods: A retrospective study was conducted of all women age 30 or younger who underwent definitive operation at our institution for primary operable breast carcinoma during one of two consecutive 20-year periods (1950–1969 or 1970–1989). All cancers were restaged according to current staging criteria. Actuarial survival and recurrence-free survival rates from the two patient eras were compared with each other and with published statistics for older breast cancer patients. Results: Eligibility criteria were met by 81 women from the 1950–1969 era and 146 women from the 1970–1989 era. Histologic diagnoses, tumor sizes, incidence of axillary nodal metastases, number of positive nodes, and American Joint Committee on Cancer stage at presentation were similarly distributed in the two eras. Despite these similarities, improved survival (p=0.009) was observed in the later era. Local recurrences were also more common (p<0.05) in the later era in association with less extensive resections. These local recurrences had an adverse impact on recurrence-free survival in the later era, but no concomitant decrease in overall survival was observed. Node-positive patients who received chemotherapy demonstrated a trend toward improved survival (p=0.06) compared with node-positive patients who did not. Survival for patients in the later era was similar to that for older women as reported in other published series. Conclusions: The stage of presentation of breast cancer in women 30 years or younger appears unchanged from prior decades, but survival has improved in association with the use of less extensive surgical resections and the introduction of cytotoxic chemotherapy. With current treatment, primary operable breast cancer in young women appears to have a similar prognosis to breast cancer in older women.Results of this study were presented at the 47th Annual Cancer Symposium of The Society of Surgical Oncology, Houston, Texas, March 17–20, 1994, and was judged Best Clinical Paper in the Resident/Fellow Essay Contest.     

Optimal Duration and Temperature of Prewarming

Background: Core hypothermia developing immediately after induction of anesthesia results largely from an internal core-to-peripheral redistribution of body heat. Although difficult to treat, redistribution can be prevented by prewarming. The benefits of prewarming may be limited by sweating, thermal discomfort, and efficacy of the warming device. Accordingly, the optimal heater temperature and minimum warming duration likely to substantially reduce redistribution hypothermia were evaluated.

Methods: Sweating, thermal comfort, and extremity heat content were evaluated in seven volunteers. They participated on two study days, each consisting of a 2-h control period followed by 2 h of forced-air warming with the heater set on "medium" ([nearly equal] 40 degrees Celsius) or "high" ([nearly equal] 43 degrees Celsius). Arm and leg tissue heat contents were determined from 19 intramuscular needle thermocouples, ten skin temperatures, and "deep" foot temperature.

Results: Half the volunteers started sweating during the second hour of warming. None of the volunteers felt uncomfortably warm during the first hour of heating, but many subsequently did. With the heater set on "high," arm and leg heat content increased 69 kcal during the first 30 min of warming and 136 kcal during the first hour of warming, representing 38% and 75%, respectively, of the values observed after 2 h of warming. The increase was only slightly less when the heater was set to "medium."     

Treatment of Vitamin B12 Deficiency after Gastric Surgery for Severe Obesity

Background: Vitamin B₁₂ deficiency after gastric surgery for obesity is due to a failure of separation of vitamin B₁₂ from protein foodstuffs and to a failure of absorption of crystalline vitamin B₁₂ in the presence of intrinsic factor. The purpose of this study was to determine which of four oral doses of crystalline vitamin B₁₂ was most effective in treating vitamin B₁₂ deficiency in 102 patients. Methods and Results: At time of entry into the study, the patients had a serum vitamin B₁₂ < 100 pmol L ⁻¹, were 29.9 ± 21.7 months post-op, were 37 ± 8 years old and had a body mass index of 30 ± 6 kg m⁻². Eight (8%) had had a vertical banded gastroplasty and 94 (92%) a gastric bypass. For the first 3 months all patients received 350 μg per day of crystalline vitamin B₁₂ and all increased their serum vitamin B₁₂ levels to over 100 pmol L⁻¹. The patients were then assigned to receive for a further 3 month period one of four oral doses of crystalline vitamin B₁₂-100 μg, 250 μg, 350 μg and 600 μg. Serum vitamin B₁₂ levels were greater than 150 pmol L⁻¹ after 6 months in 83.3% of patients who received 100 μg; 92.3% of patients who received 250 μg; 94.7% after 350 μg and 95.2% after 600 μg (p%0.525). Conclusion: At least 350 μg per day is the appropriate oral dose of crystalline vitamin B₁₂ after gastric surgery for obesity to correct low serum vitamin B₁₂ levels in 95% of patients.