Assessment of two methods of gastric decompression for the initial management of gastric dilatation-volvulus.

OBJECTIVE: To assess gastric trocarization and orogastric tubing as a means of gastric decompression for the initial management of gastric dilatation-volvulus. METHODS: Retrospective review of 116 gastric dilatation-volvulus cases from June 2001 to October 2009. RESULTS: Decompression was performed via orogastric tubing in 31 dogs, gastric trocarization in 39 dogs and a combination of both in 46 dogs. Tubing was successful in 59 (75·5%) dogs and unsuccessful in 18 (23·4%) dogs. Trocarization was successful in 73 (86%) dogs and unsuccessful in 12 (14%) dogs. No evidence of gastric perforation was noted at surgery in dogs undergoing either technique. One dog that underwent trocarization had a splenic laceration identified at surgery that did not require treatment. Oesophageal rupture or aspiration pneumonia was not identified in any dog during hospitalization. No statistical difference was found between the method of gastric decompression and gastric compromise requiring surgical intervention or survival to discharge. CLINICAL SIGNIFICANCE: Orogastric tubing and gastric trocarization are associated with low complication and high success rates. Either technique is an acceptable method for gastric decompression in dogs with gastric dilatation-volvulus.

Cardiac function after eight hour storage by using polyethylene glycol hemoglobin versus crystalloid perfusion.

Efforts to extend myocardial preservation for transplantation by crystalloid perfusion have been limited by edema and compromised function. We hypothesized that hypothermic perfusion preservation with a polyethylene glycol (PEG) conjugated hemoglobin solution may extend preservation times. The purpose of this study was to compare cardiac function after continuous perfusion by using a hypocalcemic, normokalemic crystalloid perfusate with and without the addition of PEG-hemoglobin (Hb). The hearts of 20 anesthetized and ventilated New Zealand White rabbits were harvested after cold cardioplegic arrest. Group I (n = 10) hearts were continuously perfused with a hypocalcemic, normokalemic 3% bovine PEG-Hb solution at 20 degrees C and 30 mm Hg for 8 hours. Group II (n = 10) hearts were continuously perfused with an identical crystalloid solution without PEG-Hb for 8 hours under the same conditions as group I hearts. Cardiac function was measured with a left ventricular force transducer after transfer to a standard crystalloid Langendorff circuit at 37 degrees C and an aortic root pressure of 59 mm Hg. After 8 hours of perfusion preservation, heart rate was similar for groups I and II (p = not significant [NS]). Coronary blood flow after and during preservation was similar between PEG-Hb and crystalloid preserved hearts (p = NS). Left ventricular developed pressure, peak dP/dt, and peak -dP/dt were superior in hearts preserved with PEG-Hb. Percent water of total ventricular weight was 82.0% for group I and 81.6% for group II (p = NS). Continuous perfusion preservation of rabbit hearts for 8 hours with a hypocalcemic normokalemic PEG-Hb based solution at 30 mm Hg and 20 degrees C yields left ventricular function that is superior to perfusion with a similar crystalloid solution without PEG-Hb, despite similar myocardial edema and coronary flow. Extended cardiac perfusion preservation with this PEG-Hb based solution deserves further study, including comparison with traditional cardioplegic preservation solutions.

Pulmonary vascular pressures increase after lung volume reduction surgery in rabbits with more severe emphysema.

BACKGROUND: Emphysema is a chronic disease of the lungs with destruction of terminal alveoli and airway obstruction. Lung volume reduction surgery (LVRS) is being investigated for the treatment of emphysema. Increasing resection volumes with LVRS may lead to worsening of carbon monoxide diffusing capacity (Dlco) despite improvement in compliance and flow. We hypothesized that the pulmonary circulation-related parameters, pulmonary artery pressure (PAP) and diffusing capacity (Dlco), may be used as indicators of the maximally tolerated LVRS resection volume. METHODS: Emphysema was induced in 55 rabbits by endotracheal nebulization, with either single 15,000-unit (mild emphysema) or three 11,000-unit (moderate emphysema) doses of elastase. At Week 6, bilateral LVRS was performed via median sternotomy with an endoscopic stapler. Single-breath Dlco, static compliance, and PAP were measured prior to emphysema induction, preoperatively, and 1 week following LVRS. Animals were divided into the following groups: Group I (mild emphysema, <3 g resected), group II (mild emphysema, >3 g resected), group III (moderate emphysema, <3 g resected), group IV (moderate emphysema, >3 g resected). RESULTS: All animals having LVRS had immediate postoperative increase in pulmonary vascular resistance (PVR) following lung resection. Mean PAP, however, remained elevated when measured 1 week after LVRS (sacrifice) in animals with moderate emphysema. This is in contrast to animals with mild emphysema, in which follow-up PAPs approached preoperative baseline. CONCLUSION: These finding suggests that sustained increased PVR, denoted by elevated PAP, is more likely to occur after LVRS in animals with more severe emphysema and larger volume resection. The spirometric and compliance benefits of greater resection volumes have to be weighed against the compromise in pulmonary vasculature in the effort to determine the ideal resection volume for various degrees of emphysema.

Glycoprotein IIb/IIIa receptor inhibitor attenuates platelet aggregation induced by thromboxane A2 during in vitro nonpulsatile ventricular assist circulation.

A recent development in antithrombotic research allows the inhibition of platelet aggregation via protection of the glycoprotein IIb/IIIa receptor on the platelet membrane. We hypothesized that a GP IIb/IIIa receptor inhibitor would inhibit thromboxane-induced platelet aggregation during circulation in our in vitro ventricular assist device (VAD) circuit and preserve long-term platelet function. Twenty-one in vitro nonpulsatile centrifugal VAD circuits were simulated for 4 days using 450 ml of fresh human whole blood with or without glycoprotein IIb/IIIa receptor inhibitor (tirofiban). Platelet aggregation and degranulation were measured in whole blood induced by ristocetin, collagen, ADP, and thromboxane A2 (TXA2). The tirofiban-treated group preserved the platelet count and tended to exert these beneficial effects by inhibiting pathologic platelet aggregation induced by TXA2, collagen, and ADP as well as degranulation. Tirofiban may be useful in preserving platelet number and function during clinical VAD use.

Relationship between amount of lung resected and outcome after lung volume reduction surgery.

BACKGROUND: Lung volume reduction surgery (LVRS) is being actively investigated for palliative treatment of severe emphysema. Considerable focus is directed toward patient selection and outcomes of LVRS. However, there is little information available regarding surgical methods to guide optimal extent of resection. We hypothesized that acute improvement and long-term survival after bilateral staple LVRS would be related to the extent of tissue resected. METHODS: The relationship between acute improvement in forced expiratory volume in 1 second and forced vital capacity was examined as a function of the total grams of lung tissue resected in 237 patients who underwent bilateral staple LVRS by a single group of surgeons. Overall survival was assessed based on extent of resection by quartiles of tissue weight resected using Kaplan-Meier survival methods. RESULTS: Improvement in forced expiratory volume in 1 second and forced vital capacity correlated with extent of tissue resected (p < 0.01), although there was considerable variability to individual response (r = 0.3). In contrast, there was no apparent relationship between the amount of tissue resected and overall postoperative survival (p = 0.7). CONCLUSIONS: There is a correlation between the amount of tissue resected and improvement in forced expiratory volume in 1 second and forced vital capacity after bilateral staple LVRS, with generally greater postoperative improvement after larger volume resections. However, there does not appear to be greater long-term survival with larger volume resections despite greater improvement in spirometry. This study suggests that factors other than improvement in spirometric variables may govern optimal LVRS resection volumes and long-term outcome. Future studies will clearly be needed in this important area of LVRS emphysema research.

Improved patient outcome after surgical treatment for loculated empyema.

BACKGROUND: Empyemas complicate the hospital course of many patients. Advanced stages of empyema often require surgical intervention. METHODS: A retrospective review of 70 adult patients with empyema, hospitalized between the years of 1992 and 1997, was performed. Data on age, length of stay, comorbidities, diagnostic studies, and treatment was obtained. We compared patient outcome from patients with loculated empyemas who had surgical treatment and those who were managed nonsurgically. RESULTS: Seventy patient records were reviewed, 37 of which were of patients with loculated empyemas. Parapneumonic empyemas comprised 60% of all cases. Chest radiographs, computed tomography scan, and thoracentesis were the most common studies performed in both groups. Thirty-three patients with the radiographic finding of a loculated empyema were treated with either surgical decortication or tube thoracostomy. CONCLUSION: Empyemas at various stages of development require different forms of therapy; advanced empyemas treated early with decortication have a shorter duration of treatment, lower incidence of recurrence and fewer complications.

The role of beta-lactam antimicrobials as single agents in treatment of intra-abdominal infection.

Broad-spectrum beta-lactam antibiotics have several advantages in the treatment of intra-abdominal infections. These agents are effective against gram-negative rods and anaerobes, reach therapeutic levels rapidly after parenteral administration, and, in the absence of penicillin allergy, generally exhibit low toxicity. The second-generation cephalosporins (e.g., cefoxitin, cefotetan) are used widely in surgical prophylaxis, trauma, and treatment of mild-to-moderate community-acquired infections, but limitations in their spectra and microbial resistance restrict their utility in more serious infections. Extended-spectrum penicillin/beta-lactamase-inhibitor combinations are effective in the treatment of intra-abdominal infections and include enterococci in their spectrum. Gram-negative aerobe resistance has developed to ampicillin/sulbactam. Piperacillin/tazobactam, a ureidopenicillin with increased gram-negative coverage and enhanced antipseudomonal activity, has proved to be effective in clinical trial therapy for intra-abdominal infections. The very broad spectrum carbapenems--imipenem/cilastatin and meropenem--are effective for serious infections or resistant organisms and are often used in the intensive care unit or for nosocomial intra-abdominal infection. These classes of beta-lactams comprise a range of antimicrobials that can be targeted effectively as single agents to both prevention and treatment of intra-abdominal infection.

Compliance and functional residual capacity after staple versus combined staple/holmium laser lung volume reduction surgery in a rabbit emphysema model.

BACKGROUND: There is some evidence to suggest that laser exposure, when added to standard staple reduction techniques, may result in improved physiologic response to lung volume reduction surgery (LVRS). In this study, we compared physiologic responses of staple LVRS with combined staple/laser in a rabbit emphysema model. METHODS: Ninety-three New Zealand White rabbits underwent emphysema induction with aerosolized elastase 4 weeks before surgery and were killed 1 week after surgery. Treatment groups were bilateral moderate volume staple LVRS (< or =3 g, n = 39), combined moderate volume staple (< or =3 g)/holmium laser LVRS (n = 18), large-volume staple LVRS (> or =3 g, n = 27), or sham surgery (n = 9). RESULTS: Decrease in postoperative static respiratory system compliance by combined moderate-volume staple/laser treatment (1.22 cc/cm H2O) was similar to large-volume staple resection (1.40 cc/cm H2O, p = 0.39), and superior to moderate staple resection (0.82 cc/cm H2O, p = 0.01) or sham surgery (0.09 cc/cm H2O, p = 0.0001). Functional residual capacity decrease was greater after combined moderate staple/laser resection (6.46 cc) than large-volume staple resection (4.52 cc, p = 0.33), moderate-volume staple resection (4.59 cc, p = 0.43), or sham surgery (4.10 cc, p = 0.29). Perioperative mortality was highest after laser/staple LVRS (22%, 4/18). CONCLUSIONS: In this rabbit model, combined staple/ holmium laser reduction for emphysema results in significant improvement in compliance and trends toward improvement in functional residual capacity above staple reduction alone, but with higher mortality.

Hypoadrenocorticism as the primary manifestation of lymphoma in two cats.

Hypoadrenocorticism secondary to bilateral lymphomatous invasion of adrenocortical tissue was diagnosed in 2 adult castrated domestic shorthair cats. In both cats, findings during initial physical examination (ie, lethargy, anorexia, weight loss, and severe weakness) were consistent with severe hypoadrenocorticism. Hyperkalemia, hyponatremia, and azotemia were also detected, which were consistent with hypoadrenocorticism. Hypoadrenocorticism was documented on the basis of finding low baseline and ACTH-stimulated serum cortisol concentrations. The cats initially responded well to treatment, but both owners chose to have the cat euthanatized. Multicentric lymphoma with infiltration and destruction of the adrenal glands was confirmed during necropsy.

Diffusing capacity limitations of the extent of lung volume reduction surgery in an animal model of emphysema.

OBJECTIVE: The purpose of this study was to investigate in an elastase-induced emphysema rabbit model the effects of increasing resection volumes during lung volume reduction surgery on pulmonary compliance, forced expiratory air flow, and diffusing capacity to assess factors limiting optimal resection. METHODS: Emphysema was induced in 68 New Zealand White rabbits with 15,000 units of aerosolized elastase. Static respiratory system compliance, forced expiratory flow, and single-breath diffusing capacity were measured before the induction of emphysema, after the induction of emphysema, and 1 week after a bilateral upper and middle lobe lung volume reduction operation. RESULTS: Static respiratory system compliance with 60 mL insufflation above functional residual capacity increased with emphysema induction and then decreased progressively with resection of larger volumes of lung tissue (P =.001 by analysis of variance). Expiratory flow improved after lung resection in the rabbits with large resection volumes. In contrast, diffusing capacity tended to deteriorate with larger resection volumes (P =. 18). CONCLUSION: Improvements in respiratory system compliance and forced expiratory flow after lung volume reduction operations may account for the improvements seen clinically. Declines in diffusing capacity with extensive lung reduction may limit the clinical benefits associated with greater tissue resection volumes. Future investigations with animal models may reveal other physiologic parameters that may further guide optimal lung volume reduction procedures.

Pulmonary artery pressure: an intraoperative guide to limiting resection volume.

Lung volume reduction surgery (LVRS) has shown promising results in severe emphysema. However, intraoperative indicators are needed to define optimal resection volumes. Diffusing capacity (DLCO) worsens with larger LVRS and may correlate with pulmonary artery (PA) pressure. We hypothesized that there would be a greater increase in PA pressures with larger volume LVRS in an inhaled elastase animal emphysema model. Twenty-one rabbits were induced with 15,000 units of elastase via an endotracheal tube. Four weeks later, bilateral LVRS was performed through a median sternotomy using an endoscopic stapler. PA pressures were measured prior to LVRS, immediately after LVRS, and at sacrifice. Single-breath DLCO, static pressure-volume relationships, and forced expiratory flows were measured prior to induction and at corresponding times to PA pressures. Systolic PA pressures increased in both groups immediately after LVRS (small: 2. 67 +/- 9.2 mm Hg, ANOVA, P = 0.023; large: 3.8 +/- 8.5 mm Hg, P = 0. 002), and then decreased at time of sacrifice 1 week later (small: 9. 43 +/- 4.8 mm Hg, ANOVA, P = 0.053; large: 5.2 +/- 7.3 mm Hg, P = 0. 552). The decrease, at sacrifice, in PA pressures was greater for small LVRS animals than large LVRS animals. The mortality rate (MR) for the small resection group was 0%, whereas that for the large resection group was 24%. The MR associated with larger LVRS was appreciably greater than that associated with small LVRS. These studies suggest that PA pressures may prove to be a useful intraoperative indicator for limits of resection.

Protection of platelet glycoprotein IIb/IIIa receptor complex preserves platelet function during in vitro ventricular assisted circulation.

Platelet dysfunction probably contributes to bleeding associated with ventricular assist devices (VADs). Previous evidence suggests that VAD associated platelet dysfunction may be due to dysfunction of the platelet fibrinogen receptor. The purpose of this investigation was to test the hypothesis that selective protection of platelet fibrinogen receptor preserves platelet aggregating ability during in vitro ventricular assisted circulation. Eight in vitro nonpulsatile centrifugal VAD circuits were simulated for four days using 450 ml of fresh human whole blood. Temperature, activated clotting time, pH, PCO2, PO2, Ca2+, and glucose were maintained at physiologic values. Flow was maintained at a constant 2.0 L/min/m2. We examined whole blood platelet aggregation induced by ristocetin, collagen, and adenosine diphosphate (ADP). We added a highly specific reversible inhibitor (MK-383) of the glycoprotein (GP) IIb/IIIa receptor complex before start of circulation to the final four VAD experiments. ADP induced aggregation decreased within the first hour of circulation. Ristocetin and collagen induced aggregation decreased to negligible levels after 10 hours of circulation. With MK-383, ristocetin induced aggregation was preserved. Addition of MK-383 did not alter the decrease of ADP and collagen induced aggregation. These results suggest platelet aggregating ability is maintained with protection of the platelet fibrinogen receptor during in vitro ventricular assisted circulation.

Direct pharmaceutical analysis of bisphosphonates by capillary electrophoresis.

Bisphosphonate compounds have been studied as a class of potential drugs for the treatment of various bone diseases. However, the analyses of these compounds are problematic because most of them do not contain strong chromophores. Based on the unique structures of these compounds, we have employed a capillary electrophoresis (CE) technique for the characterization of these compounds in pharmaceutical dosage formulations. In this study, two CE methods were developed for the determination of a bisphosphonate compound, 2-thioethane-1,1-bisphosphonic acid. The first method involved the use of an uncoated column, a phosphate buffer, and hydrostatic injection with direct UV absorbance detection. The method showed excellent resolution and precision with a reasonable detection limit of 30 microg/ml. Sensitivity was further improved using a glycerol-coated column, together with a phosphate buffer of higher concentration and electrokinetic injection under sample stacking conditions. This modified method revealed a significant improvement in sensitivity with a detection limit of about 50 ng/ml. Both methods demonstrated high simplicity and excellent reproducibility and were successfully applied to the quantitative analyses of pharmaceutical dosing solutions.

The use of fluorescent probe molecules for detection in capillary electrokinetic separations.

On-column fluorescence labeling using hydrophobic probe molecules is described for the enhancement of detection in capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC). Experimental details are presented for the detection of alkyl sulfate surfactant/micelle systems using the probe 2-p-toluidinonaphthalene-6-sulfonate. Using this labeling scheme, laser fluorimetry is employed to determine sodium dodecyl sulfate in a generic, commercial soap product. The influence of probe molecule concentration on calibration plots and analyte mobility is also presented. The utility of indirect detection for MECC is demonstrated with the addition of 1-anilinonaphthalene-8-sulfonate to the micellar mobile phase. A brief discussion of the analytical merits of this mode of detection is presented.

Evaluation of abnormal genital bleeding.

Irregularities of the menstrual cycle, including abnormal genital bleeding, can occur throughout a woman's life cycle. An understanding of the normal menstrual cycle is necessary before evaluation and management of an irregular cycle. Several disorders are defined and described, including appropriate evaluation and management protocols.