Relationship between venous and arterial carboxyhemoglobin levels in patients with suspected carbon monoxide poisoning

STUDY OBJECTIVE

To test the hypothesis that venous carboxyhemoglobin (V-COHb) levels accurately predict arterial (A-COHb) levels.

DESIGN

Prospective comparison of A-COHb and V-COHb levels in patients with suspected carbon monoxide (CO) poisoning.

SETTING

Municipal hospital emergency department with contiguous multiplace hyperbaric chamber staffed 24 hours a day.

PARTICIPANTS

Unselected convenience sample of 61 adults with suspected CO toxicity.

INTERVENTION

Simultaneous sampling of arterial and venous blood.

RESULTS

Correlation between V-COHb and A-COHb showed an r value of .99 (95%CI, .99 to .99), and an r2 value of .98. Agreement between V-COHb and A-COHb levels was examined by use of a plot of arteriovenous differences against the mean of the two measurements. The mean arteriovenous difference was .15% COHb (95%CI, .13% to .45%), with 95% of the differences ranging from 2.4% COHb to -2.1% COHb.

CONCLUSION

Venous COHb levels predict arterial levels with a high degree of accuracy. Patients with suspected CO poisoning can be screened with the use of venous blood, without the need for arterial puncture.

Thrombosis of abdominal aortic aneurysms

The usual complication of abdominal aortic aneurysms is rupture. Although thrombosis of peripheral aneurysms is common, thrombosis of abdominal aortic aneurysms is rare. Sudden thrombosis of abdominal aortic aneurysms constitutes a surgical emergency, with a mortality of 50 percent. The patient often presents with cool and mottled skin, and with severe pain from the umbilicus to the lower extremities. Femoral pulses are rarely present, and neurologic deficits below the level of occlusion are common. We reviewed four recent patients with thrombosed abdominal aortic aneurysms. They presented with a range of symptoms that included impotence, abdominal pain, lower extremity pain, coolness, and weakness. Angiography in three of the patients revealed complete occlusion of the aorta. The fourth patient did not undergo angiography because of hemodynamic instability. Three of the four patients underwent thrombectomy, aneurysmectomy, and bypass grafting. The other patient underwent axillofemoral bypass grafting in lieu of aneurysmectomy because of severe coronary arteriosclerotic heart disease. All patients did well postoperatively. Our limited experience suggests that prompt diagnosis and surgical management of patients with thrombosed aortic aneurysms can lead to a successful outcome.

Iodine125 interstitial brachytherapy in the treatment of carcinoma of the lung

In a prospective study, 14 patients with primary non-oat cell lung carcinoma were treated with intraoperative Iodine125 (I125) implantation of the lung tumor via lateral thoracotomy or median sternotomy. Staging mediastinal node dissection was performed in each case. Patients were selected when wedge or segmental resections were not technically feasible, such that lobectomy or completion pneumonectomy would have been required or pulmonary function studies were poor. Doses ranged from 8,000 cGy at the periphery to 20,000 cGy at the center. With a minimum 12 month follow-up, mean and median survivals were 16.7 and 15.1 months, respectively. Local control was achieved in 10 of 14 patients (71%) with all local failures occurring in pathologic stage III patients. When separated according to tumor size, local control was obtained in six of seven tumors of less than 3 cm and four of five tumors of 3-5 cm. Both cases with masses greater than 5 cm failed locally. There was one operative mortality and two postoperative complications. All other patients were discharged within one week of surgery. There was no radiation pneumonitis. I125 lung brachytherapy is an excellent alternative treatment for T1 and T2 tumors when medical conditions preclude curative resection.

Absorbable versus permanent mesh in abdominal operations

Because previous studies evaluating prosthetic mesh have yielded conflicting results, we compared two permanent (polypropylene and polytetrafluoroethylene) and two absorbable (polyglactin and polyglycolic acid) meshes with respect to histologic appearance, development of adhesions, tensile strength and occurrence of hernias in rabbits in which defects of the abdominal wall measuring 2 by 3 centimeters were repaired with one of the meshes. Twenty experiments were performed with each material, and observations were made at two, five, seven and ten weeks. The inflammatory response was minimal with all products. Adhesions were more marked with polypropylene (Marlex) than with polytetrafluoroethylene (Gore-tex); there was no difference between the absorbable meshes. In vitro tensile strength measurements at ten weeks indicated that Marlex was superior to the other materials, and between the absorbable products, polyglactin (Vicryl) was superior to polyglycolic acid (Dexon). No hernias were observed with the nonabsorbable meshes, but all of the rabbits repaired with absorbable meshes had ventral hernias by the tenth week. Thus, absorbable meshes are not indicated when prolonged tensile strength is required, but they may be useful for other purposes, including the temporary repair of fascial defects, since evisceration was not observed.