To the Editor:
Pericardial tamponade restricts diastolic filling of the heart [1-5]. Then, high intravascular volume and preload are required for adequate and end-diastolic volume and stroke volume. Increased heart rate and contractility and peripheral vasoconstriction help maintain blood pressure in the face of decreased stroke volume [1-4]. Any anesthetic (including ketamine and etomidate) or even positive pressure ventilation  can decrease preload, afterload, contractility, or heart rate and precipitate cardiovascular collapse [1,3,7-9].
Accordingly, removal of fluid from the pericardial sac should always be considered before anesthesia induction for pericardial tamponade. Percutaneous pericardiocentesis is often not helpful in traumatic pericardial tamponade [2,7] because clots may prevent aspiration of blood , continued hemorrhaging rapidly refills the pericardial sac with blood [2,6,7], and the needle can traumatize the heart with additional hemorrhage into the pericardial sac . Pericardiocentesis, however, can be a temporizing measure in the severely compromised patient [4,7,8] until definitive surgical establishment of a pericardial window. A pericardial window can be established under local anesthesia  via the subxiphoid or lateral thoracotomy approach [1,2,5,8,9]. The subxiphoid approach is less useful for trauma because limited surgical exposure may preclude repair of cardiac wounds . However, a pericardial window during awake lateral thoracotomy may be both poorly tolerated and dangerous in the distressed, moving patient .
A blunt trauma victim  recently presented for an emergent surgical pericardial window for recurrent acute pericardial tamponade. Although the patient was not hypotensive, jugular venous distention, pulsus paradoxus [1,3,7], patient distress , and echocardiographic signs were present. As an alternative to endotracheal intubation after induction of anesthesia with cardiovascular depressant anesthetics, we considered awake intubation of the trachea without sedation; we found no reports of this technique in the literature. With persuasive explanation of the procedure to the patient (but without sedation) , along with lidocaine topical anesthesia to the pharynx, larynx, and trachea, we placed an orotracheal tube over a bronchoscope in a few minutes without patient reaction. Then, anesthesia was gently induced (N (2) O, isoflurane, and fentanyl) without cardiovascular depression. The flexible bronchoscope was chosen as the least stimulating technique for awake intubation. In the trauma patient, awake fiberoptic intubation may also be the ideal intubation technique if a full stomach and a cervical spine injury coexist. We further speculate that awake fiberoptic intubation, which avoids depressant anesthetics, could be considered in other conditions of decreased cardiovascular reserve, such as ischemic heart disease.
This work was supported in part by National Heart, Lung, and Blood Institute Grant HL-42637.
Peter H. Breen, MD, FRCPC
Mark A. MacVay, MD
Department of Anesthesiology
University of California at Irvine
UCI Medical Center, Orange, CA 92613
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