Arteriovenous malformation, complications, and perioperative anesthetic management

Arteriovenous malformations (AVMs) are the most common intracranial vascular malformation, with an estimated occurrence of 1:5000-1:2000 persons. The repair requires careful embolization, often followed by stereotactic radiosurgery and can also include open craniotomy. Preoperatively, patients may be healthy or dramatically unstable, as 30-50% of these cases present with acute cerebral hemorrhage. One of the most important considerations for the anesthesiologist should be attempting to achieve hemodynamic stability in the face of potential increased intracranial pressure and subsequent vulnerability of the tissues to ischemic insult. Knowledge of the risks and hazards of the procedure and collaboration with specialists, including neuroradiologists, critical care physicians, and potentially neurosurgeons, ultimately form the basis for appropriate management. AVM's can lead to potentially fatal ischemic or hemorrhagic complications that may occur in up to 8% of cases. The protection of the airway, adequate monitoring, and maintaining cardiovascular and neurological stability, are critical. Further, in the setting of a radiological suite, peripheral location considerations involving equipment, monitors, and appropriate drugs and sustaining the patient's immobility during the radiological procedures, while managing potential perioperative complications are all essential.

Septic shock: review and anesthetic considerations

Sepsis and shock are severe conditions that, when together, may cause multiple organ failure. The anesthesiologist must be able to take a careful history and physical, as well as be aware that additional tests are necessary to assess the patient status, as preoperative systemic blood pressure is not indicative of adequate volume status. In preparation for surgery, one must anticipate dysfunction and have adequate blood products and antibiotic at hand. Ketamine is notable for induction in these patients because it is less likely to decrease systemic vascular resistance too quickly. One must not take this lightly, as death may ensue if proper management is not taken.

Referring Physicians' Attitudes Toward International Interpretation of Teleradiology Images

OBJECTIVE

We evaluated referring physician attitudes toward the international interpretation of radiologic images.

MATERIALS AND METHODS

A five-question, scenario-based survey describing features of a hypothetic local radiology firm compared with those of its hypothetic overseas counterpart, international radiology, was sent by mail to 350 physicians from a broad range of medical and surgical specialties. One hundred nineteen physicians responded, for a response rate of 34%. Referring physicians were asked to indicate their preference for local versus international interpretation in each scenario using a 5-point Likert scale, with a score of -2 indicating a strong preference for international services, 0 indicating no preference, and 2 indicating a strong preference for local services.

RESULTS

When all variables are held to be equal, referring physicians strongly prefer local services (mean score, 1.77; SD, 0.77). When international teleradiology provides either a 2-day faster turnaround time for reports or a 30 dollars lower out-of-pocket cost to the patient, referring physicians still prefer local services, although less than they did with all variables held equal (mean score, 0.42-0.44; SD, 1.30-1.40). When international teleradiology provides both a 2-day faster turnaround time and a 30 dollars lower out-of-pocket cost to the patient, referring physicians preferred international teleradiology, albeit only slightly (mean, -0.25; SD, 1.50). Finally, when the credentials of the international radiologists are perceived to be less than those of the local radiologists, even in the face of faster turnaround time and 30 dollars lower cost to the patient, referring physicians overall strongly prefer local services (mean, 1.51; SD, 0.86).

CONCLUSION

Referring physicians prefer local interpretation of radiologic images to international interpretation when all things are equal. However, the timeliness of image interpretation and the cost to the patient are important factors in this decision.

Influence of Potassium Dichromate on Tracheal Secretions in Critically Ill Patients

BACKGROUND

Stringy, tenacious tracheal secretions may prevent extubation in patients weaned from the respirator. This prospective, randomized, double-blind, placebo-controlled study with parallel assignment was performed to assess the influence of sublingually administered potassium dichromate C30 on the amount of tenacious, stringy tracheal secretions in critically ill patients with a history of tobacco use and COPD.

METHODS

In this study, 50 patients breathing spontaneously with continuous positive airway pressure were receiving either potassium dichromate C30 globules (group 1) [Deutsche Homoopathie-Union, Pharmaceutical Company; Karlsruhe, Germany] or placebo (group 2). Five globules were administered twice daily at intervals of 12 h. The amount of tracheal secretions on day 2 after the start of the study as well as the time for successful extubation and length of stay in the ICU were recorded.

RESULTS

The amount of tracheal secretions was reduced significantly in group 1 (p < 0.0001). Extubation could be performed significantly earlier in group 1 (p < 0.0001). Similarly, length of stay was significantly shorter in group 1 (4.20 +/- 1.61 days vs 7.68 +/- 3.60 days, p < 0.0001 [mean +/- SD]).

CONCLUSION

These data suggest that potentized (diluted and vigorously shaken) potassium dichromate may help to decrease the amount of stringy tracheal secretions in COPD patients.

The Comparative Effects of Desflurane and Isoflurane on Lumbar Cerebrospinal Fluid Pressure in Patients Undergoing Craniotomy for Supratentorial Tumors

We compared the effects of desflurane and isoflurane on cerebral perfusion pressure (CPP), lumbar cerebrospinal fluid pressure (LCSFP), and mean arterial blood pressure (MAP) in patients anesthetized with desflurane or isoflurane undergoing craniotomy for supratentorial mass lesions. Additionally, emergence from anesthesia was examined to determine if neurologic function could be assessed earlier after isoflurane or desflurane anesthesia. Thirty-six patients were randomized to receive either desflurane or isoflurane for maintenance of anesthesia at 1.2 minimum alveolar concentration (MAC). Patients were hyperventilated (PaCO(2), 30 +/- 2 mm Hg) after baseline LCSFP was obtained via the subarachnoid catheter. At a MAC of 1.2, mean LCSFP was not statistically different between the two study groups either before or after hyperventilation. Additionally, CPP was not significantly different between the two groups. Finally, patient's time to respond to commands was 50% shorter in the desflurane group (30 +/- 36 min) (mean +/- SD) when compared with the isoflurane group (72 +/- 126 min); however, this was not significant (P = 0.17). In patients undergoing craniotomy for supratentorial mass lesions, desflurane and isoflurane have similar effects on CPP and MAP. Additionally, desflurane in the setting of hyperventilation does not cause significant changes in LCSFP.

IMPLICATIONS

This is the largest study to date comparing the effects of desflurane and isoflurane on patients undergoing craniotomy for supratentorial mass lesion with evidence of midline shift or edema. Neither desflurane nor isoflurane significantly altered lumbar cerebrospinal fluid pressure when moderate hypocapnia was maintained.