Do anticoagulation with heparin and protamine reversal alter thrombogenicity of coated and noncoated pulmonary artery catheters?

OBJECTIVE: To clarify the role of anticoagulation with heparin and protamine reversal on the effectiveness of heparin bonding or coating of pulmonary artery catheters in preventing thrombus formation in the Rhesus monkey. DESIGN: A controlled, unblinded, open-labeled study. SETTING: A research laboratory at Tulane School of Medicine (New Orleans, LA). PARTICIPANTS: Twenty-four anesthetized Rhesus monkeys. INTERVENTIONS: The monkeys were assigned to one of four groups. In the first group (group A), non-heparin-coated catheters were inserted into a femoral vein through an incision, advanced proximally for a distance of 30 cm, and left in place for 1 hour. In the second group (group B), heparin-coated catheters were placed and evaluated in the same manner as in group A. In the third group (group C), the primates received 3 mg/kg of heparin intravenously (i.v.) before insertion of a non-heparin-coated pulmonary artery catheter. After the catheter had been in place for 1 hour, protamine, 3 mg/kg i.v., was administered, and the catheter was left in place for an additional hour. In the final group (group D), the primates received 3 mg/kg of heparin i.v. before insertion of a heparin-coated pulmonary artery catheter. After the catheter had been in place for 1 hour, protamine, 3 mg/kg i.v., was administered, and the catheter was left in place for an additional hour. In each group, the catheter was withdrawn with the balloon inflated to minimize any stripping of thrombus from the surface of the catheter. Thrombus was removed from the catheter through a femoral vein cutdown and weighed. Laboratory values were determined for each animal, and clot formation was evaluated in each group. After completion of the study, the animals were returned to the primate breeding colony. MEASUREMENTS AND MAIN RESULTS: There were no significant differences in hematocrit, prothrombin time, partial thromboplastin time, or platelet levels among the four groups; therefore, the data were pooled. Clots were observed on five of six catheters in both groups A and C; however, clot formation was seen in one of six catheters in group B and three of six catheters in group D. There was a statistically significant difference (p < 0.01) in mean clot weight in group A (265 +/- 68 mg; range, 0 to 447 mg) compared with 13 +/- 13 mg in group B (range, 0 to 80 mg). There was no significant difference in mean clot weight in group C (104 +/- 35 mg; range, 0 to 202 mg) compared with group D (24 +/- 16 mg, range, 0 to 98 mg). Additionally, in group C, the mean clot weight was significantly less than in group A. CONCLUSION: Anticoagulation of primates with heparin before catheter insertion imparts some protection to non-coated catheters, and protamine reversal of anticoagulation with heparin may partially negate the protective effect seen with heparin-coated pulmonary artery catheters.

Introducers and protective sleeves may increase thrombogenicity of pulmonary artery catheters.

OBJECTIVE: To investigate the cause of clot formation on the surface of non-heparin coated/bonded pulmonary artery catheters. DESIGN: A controlled, unblinded, open-labeled study. SETTING: Research laboratory at Tulane School of Medicine, New Orleans, LA. PARTICIPANTS: Rhesus and African Green monkeys. INTERVENTIONS: Anesthetized monkeys (n = 24) were assigned to one of two groups. The first group (group A) had a pulmonary artery catheter inserted into a femoral vein through a cutdown without passage through an introducer or protective sleeve before insertion. In the second group (group B), the pulmonary artery catheter was passed through an introducer and protective sleeve before insertion in the femoral vein. After the study, the animals were returned to the primate breeding colony. Laboratory values were measured for each animal, and electron micrographs were taken of selected pulmonary artery catheters before and after passage of these catheters through the introducer sheath and/or protective sleeve. MEASUREMENTS AND MAIN RESULTS: Between the two groups, there was a significant difference in fibrinogen level, but not in hematocrit, prothrombin time, partial thromboplastin time, and platelet count. Clots were visible on 11 of 12 catheters in group B, which was statistically significant (p < 0.01), compared with only 3 of 12 catheters in group A. The average clot weight was 0.014+/-0.014 g in group A (range, 0.00 to 0.170 g), which was statistically significant (p < 0.01), compared with 0.216 < 0.058 g in group B (range, 0.000 to 0.620 g). Electron micrographs taken after catheters were passed through an introducer and/or protective sleeve showed that both significantly altered the surface of the catheter. The surface of the catheter was smooth and homogenous in appearance before insertion. Conversely, both the introducer and protective sleeve produced marked furrowing and a nodular appearance on the catheter surface, as shown by electron micrographs. CONCLUSION: The data from this study show that the incidence of clot formation and amount of clot formed on the surface of non-heparin-coated pulmonary artery catheters are significantly greater after passage through an introducer and/or protective sleeve. The electron micrographs also show that both introducers and protective sleeves abraded the catheters and were associated with thrombus formation on the catheter. Designing less traumatic valves on these devices is warranted and recommended.

Local anesthesia infiltration as a cause of intraoperative tension pneumothorax in a young healthy woman undergoing breast augmentation with general anesthesia.

Pneumothorax may be a medical emergency. Iatrogenic pneumothorax is more common than all other forms of spontaneous pneumothorax, and surgical procedures involving the breast are a frequent setting for this. A 32-year-old, 60 kg, woman without any significant medical history underwent a bilateral breast augmentation and rhinoplasty. She underwent a routine general endotracheal anesthetic. Prior to surgical incision, the surgeon infiltrated the breast with lidocaine with epinephrine. Six hours into the surgical procedure, the patient developed hemodynamic compromise and was diagnosed with tension pneumothorax, which was treated emergently with a 14-gauge angiocatheter placed intrapleurally. The patient immediately returned to hemodynamic stability. This case report discusses iatrogenic pneumothoraces as well their most likely causes; which in this specific case was the injection of local anesthetic. Suggestions for prevention and treatment of the unusual complication are discussed.

Role of the Ah locus in suppression of cytotoxic T lymphocyte activity by halogenated aromatic hydrocarbons (PCBs and TCDD): structure-activity relationships and effects in C57Bl/6 mice congenic at the Ah locus.

Previous studies have shown that the generation of cytotoxic T lymphocytes (CTL) following allogeneic tumor challenge is suppressed in Ah-responsive C57Bl/6 mice treated with a single oral dose of the toxic, Ah receptor-binding 3,4,5,3',4',5'-hexachlorobiphenyl (HxCB). The present studies have examined the specific role of the Ah receptor in this immunotoxic response by utilizing HxCB isomers of known, varied affinity for the Ah receptor as well as by comparing effects of high-affinity Ah receptor ligands (3,4,5,3',4',5'-HxCB and 2,3,7,8-tetrachlorodibenzo-p-dioxin [TCDD]) on the CTL response of mice that differ only at the Ah locus, that is, Ah-responsive (Ahbb) and Ah-nonresponsive (Ahdd) congenic C57Bl/6 mice. Correlative changes in thymic weight, serum corticosterone (CS) levels, and spleen cellularity were also measured. The potency of HxCB congeners (3,4,5,3',4',5'-; 2,3,4,5,3',4'-; 2,4,5,2',4',5'-) and 2,3,7,8-TCDD to suppress the CTL response, to reduce spleen cellularity, to cause thymic atrophy, and to elevate serum CS levels was directly correlated with the binding affinity of the congener for the Ah receptor. Furthermore, these parameters of immunotoxicity in Ahdd C57Bl/6 mice were significantly more resistant to alterations induced by either 3,4,5,3',4',5'-HxCB or 2,3,7,8-TCDD as compared to Ahbb C57Bl/6 mice. These results strongly support an Ah receptor-dependent immunotoxic mechanism in suppression of the CTL response following acute exposure to halogenated aromatic hydrocarbons.

Emergency management of tracheal rupture.

We have described a patient in whom tracheal rupture occurred during prolonged mechanical ventilation. Appropriate intensive respiratory care management, including the use of the minimal leak technique, was used. Our patient unfortunately had nearly every known predisposing factor for tracheal damage.

Renal transplantation in a developing country: anesthesia and other considerations.

The Renal Transplant Team at Tulane University Medical Center has been involved in training a multispecialty group of Guatemalan physicians to perform renal transplantations in Guatemala. The purpose is to train the physicians in their own country, using available equipment and personnel so that they can perform successful operations in our absence. This paper is a review of the considerations involved in the initial renal transplantation done in Guatemala by the Tulane Renal Transplant Team. The need for a preliminary site visit was paramount. Personnel, facilities, and both surgical and anesthesia equipment and supplies were carefully evaluated. The recipient was a 22-year-old man with end-stage renal disease due to chronic glomerulonephritis. The donor was a healthy 33-year-old brother. This article is not intended to review renal transplantation in the United States, but to show what is feasible in a developing country where many drugs and equipment are not available.

Does geographical location influence inflow requirements of the Bain breathing system?

A review of publications from various countries, using the Bain system with a fresh gas flow of 70 ml kg-1 min-1 and controlled ventilation, show a range of mean PaCO2 values between 36 and 43 mmHg. It was suggested that these differences could be related to the geographic location of the patient population studied. Anaesthetists from seven institutions in West Germany, England, Sweden, the United States, Australia and Canada collaborated in a preliminary study designed to find out whether these differences could be reduplicated. In 142 patients under a standard anaesthesia with controlled ventilation, PaCO2 values were determined 30 min after the fresh gas flows had been set. For 70 ml kg-1 min-1 the mean PaCO2 values ranged from 33 to 40 mmHg; for 100 ml kg-1 min-1 from 28 to 35 mmHg. Compared to the mean PaCO2 values from Canada, the results from Australia and the USA were not different and all at the lower end of this range; Sweden, West Germany and England reported significantly higher PaCO2 values. In the absence of any other obvious explanation, we suggest that patients in England and Northern Europe could have a higher CO2 output under anaesthesia than North American or Australian patients.

Comparison of intravenous and topical lidocaine in attenuating the cardiovascular responses to endotracheal intubation.

We administered lidocaine intravenously or topically to the larynx to compare the cardiovascular response to intubation between the two techniques and to determine if these responses were related to blood levels of lidocaine. Sixteen patients were randomly selected into group A (100 mg intravenous lidocaine) or group B (160 mg topical lidocaine). Neither method was completely effective in abolishing hypertension and tachycardia on intubation. The increase in pulse rate (PR) was more significant than the rise in mean arterial pressure (MAP) and was of longer duration. Significant increases in MAP were evident for less than two minutes in group A and less than three minutes in group B. Significant increases in PR were observed for approximately four minutes in group A and six minutes in group B. The average lidocaine blood level in group A was approximately 20 times that in group B at the time of intubation. The more prolonged and more significant increase in PR observed in group B indicates that intravenous administration of lidocaine may be superior to topical administration.

Pulmonary artery catheterization via the external jugular vein.

The use of pulmonary artery catheters in assessing and managing critically ill patients has become a common practice. The risks associated with insertion of the Swan-Ganz catheter via the internal jugular or subclavian vein include pneumothorax, puncture of the carotid or subclavian artery, mediastinal infiltration, and neurologic damage. I evaluated the success and complication rates associated with placement of a pulmonary artery catheter via the external jugular vein in 25 unselected consecutive patients. Catheterization was successful in 23 of 25 patients on the first attempt. In one patient there was no visible external jugular vein, and in the other the J-wire could not be passed centrally. No complications resulted. It is concluded that pulmonary artery catheterization via the external jugular vein is safe and reliable.