Faculty Bibliography

INTRODUCTION: Gastroesophageal reflux (GER) is common in children with airway disorders. Previous studies have shown an association between upper airway obstruction and GER in experimental animal models. However, the cause and effect relationship between intrathoracic airway obstruction (IAO) and GER is obscure. The goal of this study is to investigate the association between IAO and GER using the canine model. METHODS: In sedated dogs, a telemetric implant was placed subcutaneously (with one pressure sensor tip each in intrapleural space and abdomen) to monitor intrapleural pressure (IPP) and intrabdominal pressure (IAP). The IPP and the IAP were monitored intraoperatively and in conscious dogs on the 7th to 10th postoperative days. GER was assessed by determining the reflux index (RI), based on the intraesophageal pH recording performed continuously for a 24 hr period using a pH probe. After 2-3 weeks following placement of the telemetric implant, IAO was surgically created in the dog. After maintaining IAO for 2 weeks, the IPP, IAP, and pH measurements were monitored again following the same protocol as before IAO. RESULTS: After the creation of IAO, there was no significant change observed in the mean RI either in the distal (P = 0.716) or proximal (P = 0.962) esophageal lumens. The IPP became significantly more negative (P = 0.006) and the IAP turned significantly negative (P < 0.001) from being positive compared to the respective values before IAO. However, transdiaphragmatic pressure (Pdi) did not change significantly (P = 0.08). CONCLUSION: We conclude that moderate IAO does not cause GER in our animal model. It can be explained by the absence of significant change in Pdi after creation of IAO.

The use of Argatroban for treatment of heparin-induced thrombocytopenia (HIT) and for percutaneous coronary intervention in patients with HIT is well described and FDA approved. The use of Argatroban for cardiopulmonary bypass remains off label and the subject of a few case reports. We report the case of a patient with a heparin allergy requiring cardiopulmonary bypass (CPB) for mitral valve replacement. Argatroban was successfully used as anticoagulation for CPB.

Indications regarding surgical pulmonary embolectomy for treatment of submassive/massive acute pulmonary embolism remain controversial. An institutional experience with pulmonary embolectomy for acute pulmonary embolism (APE) was reviewed. A retrospective analysis of all patients undergoing pulmonary embolectomy for APE from September 2004 to January 2007 was conducted. Demographic data, clinical presentation and outcomes were analyzed. Fifteen patients underwent surgery for APE over a period of 27 months [average age 59.6 (range 35-89) years, (seven male, eight female)]. Six (40%) patients were admitted with known APE and nine patients exhibited post admission APE (seven - after surgical procedures, two - after cerebrovascular accident). Clinical presentation included dyspnea (86.67%), hemodynamic instability requiring continuous vasopressor support (40%), echocardiographic evidence of right ventricular dilatation (80%). Ten patients undergoing early/expedient embolectomy all survived while delayed surgery in the other five patients (>24 h) was associated with 60% mortality. Expanding indications for early surgical pulmonary embolectomy has stemmed from reliable echocardiographic identification of right ventricular compromise and recognition of these findings as harbingers of subsequent hemodynamic embarrassment. Our series underscores the benefit of early consideration and performance of pulmonary embolectomy in these critically ill patients

The causal relationship between gastroesophageal reflux (GER) and respiratory disorders is not well understood. Previous experimental studies that investigated this relationship were performed in anesthetized animals and used artificial acidification of esophagus for simulation of GER. In this study, we investigated the impact of GER on intrapleural pressures (IPP) in conscious, unanesthetized dogs. After the induction of appropriate anesthesia, 5 purpose-bred mongrel dogs underwent reflux-creating surgery (partial cardiomyectomy). The presence of GER was confirmed by determining the reflux index (RI) and the duration of longest reflux episode (DLRE) after 24-h intraesophageal pH-metry. IP was monitored before and after cardiomyectomy using a subcutaneously placed telemetric implant with its pressure-sensor catheter tip inserted into the pleural space. Partial cardiomyectomy resulted in a significant increase in RI from a preoperative mean value of 0.38 +/- 0.21 to 7.52 +/- 2.56%, and DLRE from 1.22 +/- 1.12 to 36.80 +/- 12.71 min, as recorded by the proximal sensor of the pH probe. A similar trend was observed at the distal sensor. After cardiomyectomy, the negative inspiratory IPP significantly increased from 17.2 +/- 7.9 to 28.4 +/- 9.7 mm Hg. A similar effect was observed in the negative expiratory IPP. The negative inspiratory IPP had a significant correlation with both RI (R = 0.932) and DLRE (R = 0.899). Cardiomyectomy causes GER, the severity of which correlates with negative inspiratory IPP in a dog model. The suggested model allows for the investigation of the pathologic association of GER with respiratory disorders in conscious animals.

Laryngeal exposure to acid and aspiration of gastric contents may lead to severe respiratory disorders. This study utilizes the canine model of Gastroesophageal reflux (GER) to identify whether lower esophageal dysfunction is associated with upper and lower airway pathology. MATERIALS AND METHODS: Five mongrel dogs underwent GER-creating surgery (partial cardiomyectomy). Laryngeal reflux finding score (RFS), lipid-laden macrophage index (LLMI) and BAL fluid cell differential were obtained before and after surgery. RESULTS: Partial cardiomyectomy in dogs significantly increased the Reflux index (RI) from 0.38 +/- 0.21% to 7.56 +/- 2.89% (P = 0.048), the duration of the longest reflux episode (DLRE) from 1.22 +/- 1.19 min to 66.2 +/- 42.03 min postoperatively (P = 0.049) and the total number of episodes in 24 hr from 2.06 +/- 1.03 to a postoperative value of 19.24 +/- 4.79. There was no statistically significant change in values for RFS, LLMI, and BAL fluid cell differential after the induction of GER. CONCLUSIONS: Acid reflux to the proximal esophagus of this animal model did not cause laryngeal exposure to acid or aspiration of gastric content. The results of this study suggest that presence of GER, secondary to lower esophageal dysfunction is not necessarily associated with upper and lower airway pathology.

BACKGROUND: Monitoring of intrapleural pressure (IPP) is used for evaluation of lung function in a number of pathophysiological conditions. We describe a telemetric method of non-invasive monitoring of the IPP in conscious animals intermittently or continuously for a prolonged period of time. MATERIALS AND METHODS: After IACUC approval, six mongrel dogs were used for the study. After sedation, each dog was intubated and anesthetized using 0.5% Isoflurane. A telemetric implant model TL11M2-D70-PCT from Data Science International was secured subcutaneously. The pressure sensor tip of the catheter from the implant was inserted into the pleural space, and the catheter was secured with sutures. The IPP signals were recorded at a sampling rate of 100 points/second for 30 to 60 min daily for 4 days. From these recordings, the total mean negative IPP (mmHg), and the total mean negative IPP for a standard time of 30 min were calculated. In addition, the actual inspiratory and expiratory pressures were also measured from stable recording of the IPP waveforms. RESULTS: In six dogs, the total mean +/- SD negative IPP was -10.8 +/- 10.6 mmHg. After normalizing with respect to acquisition time it was -13.2 +/- 11.2 mmHg/min. The actual inspiratory pressure was -19.7 +/- 15.3, and the expiratory pressure was -11.0 +/- 12.9. CONCLUSIONS: Our study demonstrates that telemetric monitoring of IPP can be performed reliably and non-invasively in conscious experimental animals. The values for IPP in our study are compatible with the results of other investigators who used different methods of IPP measurement. Further work may show this method to be helpful in understanding the pathophysiology of various breathing disorders

BACKGROUND: The circadian variation that affects atherosclerosis has not been studied in the surgical patient. The circadian variation in mortality dependent on the time of surgery was examined in patients undergoing coronary artery bypass graft (CABG) surgery. METHODS: A 4-year retrospective review of all CABG patients (n = 3140) from 1999 to 2002 was undertaken. The patients were divided into elective, urgent, and emergency cases. The cases were subdivided according to the start time of the operation as morning (7 AM to 2 PM = AM), afternoon (2 PM to 8 PM = AF), and night (8 PM to 7 AM = NT). The outcome was mortality within 30 days and compared for three different time frames: (1) AM versus AF (2) AM versus NT (3) AF versus NT for each prioritized group. Risk factors and number of anastamoses were compared for each group. Sigma Statistical package and Z-test for two group comparison were used for analysis. t-Test was used to compare age and ejection fraction. RESULTS: No statistically significant difference in mortality was observed for the elective and urgent groups for each of the time periods compared. The emergency cases had significantly increased deaths in the AM and NT compared to the AF (p < 0.01 and p < 0.05, respectively). There was no statistically significant difference with respect to age, gender, number of anastamoses performed, ejection fraction, and preoperative risk factors between groups. CONCLUSIONS: The mortality for nonemergent CABG is independent of the timing of surgery. Circadian variation does not influence the outcome in cardiac surgical patients