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Nadziakiewicz, MDSilesian Center for Heart Diseases, Zabrze, Poland
Accepted for publication January 10, 2008.
* Address correspondence to Dr Knapik, Silesian Center for Heart Diseases, ul. Szpitalna 2, Zabrze, 41-800, Poland (Email: pknapik{at}slam.katowice.pl).
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Introduction |
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The awake technique has been used primarily for beating heart operations [2–4], but it has also been proposed for valve operations and combined procedures [5, 6]. The technique is practicable, but it is unclear whether patients really benefit from its use [7].
Patients with significant chronic obstructive pulmonary disease (COPD) have higher risk in cardiac operations. Patients with mild-to-moderate COPD can be operated on quite safely, but death among elderly patients with severe COPD is so high that nonsurgical therapy is often proposed [8]. High thoracic epidural anesthesia (TEA), with complete avoidance of intubation and mechanical ventilation, could be a valuable option for such patients.
We describe an elderly patient with severe COPD in whom general anesthesia was contraindicated. We were able to perform a complex valve operation under high TEA alone. The patient had an uneventful postoperative course and excellent recovery.
A 74-year-old man with pulmonary hypertension and severely impaired left ventricular function was scheduled for urgent aortic valve replacement and mitral valve repair. The patient had extremely high operative risk. Comorbidities included severe emphysema (patient was taking oral and inhalational steroids), with forced expiratory volume in 1 second (FEV1) decreased to 33% and forced vital capacity (FVC) decreased to less than 49% of the predicted values. Oxygen saturation while breathing room air was 89%. The patient's calculated additive European System for Cardiac Operative Risk Evaluation (EuroSCORE) was 9, and the logistic EuroSCORE was 16.88%. His body weight was 57 kg, and his body mass index was 21.
The anesthesiologist and cardiac surgeon in charge decided that an attempt would be made to perform the operation under TEA alone, without endotracheal intubation. An epidural catheter was inserted at the T2-T3 interspace. All catheters and lines were inserted under local anesthesia. During that time, the patient was breathing room air and proved that he was able to maintain satisfactory oxygen saturation while lying flat on the operating table. This confirmed that an awake cardiac operation was feasible in this patient.
The operation was performed through a median sternotomy. No problems occurred during the initial phase, but pain was reported during the sternotomy. The epidural infusion was increased, and 10 mg of ketamine was given intravenously. This resulted in a temporary respiratory arrest and desaturation, requiring hand ventilation with a face mask. Spontaneous ventilation was restored after 5 minutes, whereupon the patient's respiration was controlled by keeping his face mask tight whilst he breathed spontaneously. This enabled the anesthesiologist to provide the set mixture of oxygen and air, make sure that the airways were patent, and monitor respiration. At times, the face mask was released to communicate with the patient.
Breathing stopped when cardiopulmonary bypass (CPB) started, and the patient could not be roused any more. The face mask was released, and the patient's face was carefully observed for early detection of an abnormal breathing pattern, signs of discomfort, neurologic deterioration, and nausea or vomiting.
The patient was cooled to 28°C, and CPB lasted 72 minutes. The severely calcified aortic valve was replaced with a mechanical valve. The mitral regurgitation was repaired in 5 minutes with Alfieri technique through the aortotomy. The course of CPB was uneventful, after which the perfusionist increased the partial arterial pressure of carbon dioxide (PaCO2) level to 58 mm Hg. Infusions of adrenaline and milrinone were started electively. A Guedel airway was inserted into the patient's mouth, and a few artificial breaths were administered to eliminate atelectasis.
No signs of spontaneous respiration appeared at the termination of CBP, and naloxone (.05 mg) was given intravenously. This resulted in a gradual restoration of the respiratory function, and 5 minutes later the patient was breathing spontaneously, although he still remained unresponsive. Communication with the patient was restored during sternal closure. The patient was transferred to the postoperative intensive care unit (ICU) fully conscious, complaining only of thirst. He did not remember much of the operation.
During the procedure, arterial blood gases were measured on arrival to the operating theatre, after skin incision, after sternotomy, during CPB (4 times), after termination of CPB, and every 2 hours in the postoperative ICU. The range of pH values was 7.26 to 7.51; PaO2 and PaCO2 values are shown in Figure 1.
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Awake cardiac operations are also very controversial. Mora Mangano's well-known editorial [1] clearly stated, that "there is no place for this trick in the cardiac anesthesiologist's armamentarium."
Awake procedures are performed only in a few centers. The total number of publications (currently exceeding 20) is misleading, because the authors frequently report on their continuing experience in subsequent studies. The largest series of patients to date have been reported by Karagoz and colleagues [2], Aybek and colleagues [3], Chakravarthy and colleagues [4], Stritesky and colleagues [5], and very recently by Bottio and colleagues [6]. These five studies cover more than 90% of all reported patients.
What was the reasoning behind performing conscious cardiac operations in these five centers? Karagoz and colleagues [2], Aybek and colleagues [3], and Chakravarthy and colleagues [4] confirmed the feasibility and safety of this technique in patients undergoing beating heart procedures. Additional criteria may be found in the remaining two series [5, 6]. Stritesky and associates [5] included patients undergoing valve procedures, suggesting that the awake technique would be efficacious for patients with preoperative pulmonary dysfunction. Bottio and coworkers [6] went one stage further: Their study was performed entirely on a high-risk population undergoing heart valve operations and combined procedures. Many patients in this group had COPD (40%), pulmonary hypertension (62%), and various other comorbidities [6]. Our patient was similar to the patients in their population.
Information in the literature may sometimes be quite contradictory. The article by Bottio and colleagues [6] stated, "during valve implant patients were totally conscious and cooperative with the surgeon's suggestions," while "typically, after starting CPB the patients stopped breathing..." Proper understanding of all these "minor" technical problems is crucial for the success of the whole procedure. Such practical information may be found in our case report.
The safety of cardiac anesthesia during the awake procedure may not be comparable with the safety of general anesthesia; however, we were able to achieve satisfactory arterial blood gas results throughout the procedure and in the early postoperative period. During high epidural anesthesia, each spontaneously breathing patient should be carefully monitored for bilateral Horner's syndrome. If this occurs, infusion of local anaesthetic agents should be stopped and respiratory insufficiency may be expected [2].
Is this technique reproducible for patients with severe respiratory insufficiency?
To date, no randomized trials have compared the use of awake and conventional anesthesia techniques in a high-risk population. Such studies are urgently needed, because they will be able to answer the question whether awake cardiac operations are only a temporary trend or a firmly entrenched procedure.
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