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Ann Thorac Surg 2006;82:298-302
© 2006 The Society of Thoracic Surgeons
a Department of Anesthesia and Intensive Care, Postgraduate Institute of Medical Education and Research, Chandigarh, India
b Department of General Surgery, Postgraduate Institute of Medical Education and Research, Chandigarh, India
c Department of Cardiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
Accepted for publication February 22, 2006.
* Address correspondence to Dr Malhotra, Department of Anaesthesia and Intensive Care, PGIMER, Chandigarh, India 160012 (Email: drskmalhotra{at}yahoo.com).
| Abstract |
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METHODS: This prospective study was carried out in 20 consecutive American Society of Anesthesiologists grade I-II patients undergoing THE. Anesthetic technique included induction with thiopentone and maintenance with morphine, vecuronium, and isoflurane. In addition to routine parameters, Holter monitoring was undertaken to record the exact incidence and types of arrhythmias. "Premanipulation" or control period included duration of 30 minutes preceding mediastinal manipulation, while "during manipulation" or study period included the duration of mediastinal manipulation. The incidence of arrhythmias was studied for 48 hours in the postoperative period. The Fisher exact test was applied to analyze incidence of arrhythmias and hypotension.
RESULTS: Out of 20 patients, only 2 had arrhythmias in the premanipulation period, while 13 had arrhythmias during the manipulation period (p < 0.01). During the manipulation period, arrhythmias included supraventricular ectopics and ventricular ectopics in 2 patients each and a combination of both in 9 patients. Arrhythmias were transient and had no correlation with either duration or degree of hypotension in all the patients. However, there was a linear relationship between hypotension and duration of mediastinal manipulation. Two patients (10%) had atrial arrhythmias in the postoperative period.
CONCLUSIONS: In transhiatal esophagectomy, there is a significant incidence of both arrhythmias and hypotension during mediastinal manipulation. The incidence of arrhythmias can be minimized by limiting the duration of the manipulation. The incidence of postoperative arrhythmias was not significant.
| Introduction |
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Transhiatal esophagectomy (THE) is a widely used technique for carcinoma of the esophagus and other conditions, such as benign strictures and motility disorders [58]. However, the transhiatal approach may present a few potential problems for the anesthesiologist. Dissection of the esophagus from the posterior mediastinum can be hemodynamically challenging. Intraoperative hemodynamic disturbances like hypotension and arrhythmias may be significant and may result from compression and anterior displacement of the heart during blunt finger dissection of the esophagus from the posterior mediastinum, which interferes with cardiac filling and output [9, 10]. The severity of hemodynamic disturbances is proportionate to the duration of mediastinal manipulation that varies between 5 to 15 minutes [11]. It requires close cooperation and coordination between the surgeon and the anesthesiologist to minimize the severity of these disturbances [12]. Although hypotension and arrhythmias occurring during mediastinal manipulation are routinely observed, as well as reported [13, 14], there is a paucity of available literature highlighting the exact incidence and types of arrhythmias. Moreover, the main thrust of previous studies has been on postoperative cardiac functions after THE [11, 1519]. Adverse outcome in patients undergoing THE depends upon the duration and severity of hypotension and arrhythmias and could be detrimental to the patients with coexisting cardiac disease.
Although the occurrence of arrhythmias and hypotension has been duly observed, the aim of our study was to quantify the incidence, as well as types of arrhythmias. This was achieved in our study employing Holter monitoring in premanipulation and during manipulation periods.
| Material and Methods |
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Patients excluded from the study were those with any cardiac dysfunctions, severe pulmonary obstruction or restriction, and patients with electrolyte imbalance or on drugs such as steroids, ß-blockers, angiotensin-converting enzyme inhibitors, calcium channel blockers, and digitalis.
Nine patients were smokers but without any evidence of pulmonary dysfunction. There was a history of receiving radiotherapy and chemotherapy in 2 patients each and a combination of both in 7 patients. All the patients were premedicated with oral diazepam 0.2 mg/kg to a maximum of 10 mg on the night before, and on the morning of surgery.
After securing peripheral and right-sided central venous access, the right radial artery was cannulated to spare the left side for the surgeon's convenience to perform the cervical anastomosis. Monitoring included electrocardiogram (ECG), oxygen saturation as measured by pulse oximetry (SpO 2), temperature, urine output, central venous pressure (CVP), and direct arterial blood pressure. Warming blankets were employed to prevent hypothermia.
For a constant recording of incidence and types of arrhythmias, intraoperative Holter monitoring was instituted after induction of anesthesia. All patients received morphine (0.1 mg/kg) and thiopentone followed by succinylcholine to facilitate rapid-sequence tracheal intubation. Anesthesia was maintained with isoflurane and N2O/O2 (60:40) and ventilation controlled with vecuronium keeping end-tidal carbon dioxide (ETCO 2) within normal limits. Central venous pressure was kept at a normal level by appropriate administration of fluids before starting mediastinal manipulation. Inspired oxygen concentration was increased up to 50% to avoid the chances of transient hypoxia during mediastinal manipulation. At the end of the procedure neuromuscular blockade was reversed with neostigmine and glycopyrrolate. The same surgeon performed the mediastinal manipulation in all the patients to ensure the uniformity of the surgical technique.
Intraoperative heart rate was recorded every minute during mediastinal manipulation and every 10 minutes before and after that, while ECG, SpO 2, direct arterial pressure, and ETCO 2 were monitored continuously. The 30-minute period preceding mediastinal manipulation was taken as the "premanipulation" or control period, while that during mediastinal manipulation was taken as the "during manipulation" or study period. All the patients in this study acted as their own control.
Continuous monitoring of ETCO 2 and arterial blood gas (ABG) analysis prior to induction, and before and after mediastinal manipulation, was undertaken to exclude hypercarbia or hypoxia as the contributing factor to rhythm disturbances. Potassium levels were monitored along with ABG analysis to rule out hyperkalemia-hypokalemia as the causative factor for arrhythmias. The incidence of arrhythmias was studied for 48 hours in the postoperative period.
Statistical Analysis
Hemodynamic data during mediastinal manipulation were analyzed using the paired t test. Correlation of variables with duration of hypotension were analyzed using the Pearson coefficient of correlation. Hypotension and incidence of arrhythmias between the premanipulation and during manipulation groups were compared using the Fisher exact test.
| Results |
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Hemodynamics
Hypotension, defined as a 20% decrease in systolic blood pressure from the baseline, taken just before the start of mediastinal manipulation, occurred in 75% (ie, 15 out of 20 patients) (p < 0.01). The mean duration of hypotension was 3.05 minutes (range, 0 to 13 minutes).
The mean systolic blood pressure decreased from 125.65 mm Hg at 0 minutes to 86 mm Hg at 15 minutes. Systolic blood pressure at 5, 6, 7, 8, 9, 10, and 12 minutes was significantly less than at baseline. A similar trend was seen with diastolic and mean blood pressures. There was a linear relationship of duration of mediastinal manipulation with duration and degree of hypotension (p < 0.05) as shown in Fig 1. Blood pressures returned to normal values in all patients immediately after stoppage of mediastinal manipulation.
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| Comment |
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The unique aspect of this study was the use of Holter monitoring to observe the exact incidence and type of arrhythmias. Mediastinal manipulation was performed by the same surgeon in all patients in our study to exclude surgeons' variability as the contributing factor for the duration and skill of manipulation.
Arrhythmias
In our study, out of 20 patients only 2 (10%) had arrhythmias in the premanipulation period, while 13 (65%) had arrhythmias during the manipulation period (p < 0.01). In the premanipulation period, 2 patients had supraventricular ectopics that occurred as singlets. During manipulation, singlets occurred in 13 patients; supraventricular and ventricular ectopics in 2 patients each and a combination of both in 9 patients (Table 3). Couplets occurred in 8 patients; supraventricular in 2 patients, ventricular in 1, and a combination of both in 5 patients. Supraventricular ectopics in runs occurred in 2 patients. None of the patients had ventricular ectopics in runs. These episodes were transient and almost resolved promptly reverting to sinus rhythm when the surgeon's hand was removed from the posterior mediastinum. Arrhythmias did not correlate with hypotension. In our study, incidence of hypotension and arrhythmias was 75% and 65%, respectively, and that reverted to normal after stoppage of manipulation.
Hypoxia, hypercarbia, and electrolyte disturbances as the cause of arrhythmia were ruled out because they did not occur in any of the patients. Moreover, the patients with any coexisting cardiopulmonary disease were excluded from our study. Therefore, the arrhythmias and hypotension were exclusively due to mediastinal manipulation.
There have been some significant reports describing arrhythmias in the postoperative period. Ritchie and colleagues [16] noted up to 60% of patients developing cardiac dysrhythmias after esophagectomy that were not prevented by prophylactic digitalization. Amar and colleagues [17] reported that 13% of patients developed supraventricular tachycardia that was associated with higher intensive therapy unit admission rate and a longer hospital stay. Patti and colleagues [11] reported atrial arrhythmias, which occurred in 14 patients (32%) that were treated with digoxin and (or) verapamil. However, in our study the dysrhythmias occurred in the form of atrial fibrillation only in 2 patients (10%) that was statistically insignificant (p > 0.05). Also, it was not associated with higher intensive care unit admission rate, longer hospital stay, and a 30-day morbidity or mortality. The better outcome in the postoperative period was most likely owing to the exclusion, in our study, of patients with cardiac dysfunctions.
Hypotension
Hypotension was defined as a decrease of systolic blood pressure by 20% from the baseline. It occurred in none of the patients in the premanipulation group, in comparison with 15 out of 20 patients during manipulation (p < 0.01). The average duration of hypotension was 3.05 minutes (range, 0 to 13 minutes). The magnitude of decrease in blood pressure during mediastinal manipulation varied from 0% to 65.71%. In 4 patients, there was no decrease in blood pressure. In all the patients, blood pressure reverted to normal after removal of the surgeon's hand from the mediastinum.
Mediastinal Manipulation
The duration of mediastinal manipulation was 7.90 ± 3.49 minutes (range, 4 to 15 minutes). There was a linear relationship between duration of mediastinal manipulation and degree of hypotension (p < 0.05) as shown in Figure 1. In the study by Patti and colleagues [11], hypotension was defined as systolic blood pressure less than 90 mm Hg that occurred in all the patients with duration of hypotension varying from 4 to 60 minutes (mean, 8 minutes). Hypotension of greater than 15 minutes occurred in 32% of their patients. The risk factors for prolonged hypotension in their study were patients with cardiac disease, preoperative radiotherapy, and midesophageal tumors [11]. In these patients, there was a more gradual reverting back of blood pressure after stoppage of mediastinal manipulation. Greater duration of hypotension was associated with increased perioperative mortality. In our study, the duration of mediastinal manipulation correlated with duration of hypotension. Although 9 out of 20 patients in our study received radiotherapy preoperatively, it did not prove to be a risk factor for prolonged hypotension.
Blood Loss
The average blood loss in our study was 620 mL; that is less than that reported after transthoracic operation (1,000 mL). The amount of blood transfused varied from 0 to 2 units. In a study by Orringer and colleagues [20] average blood loss after THE was 689 mL. We did not observe the blood loss as the cause of hypotension in any of the patients.
Fluids
There may be significant third space losses during THE, thus adequate replacement of fluids and close monitoring of blood pressure and urine output are mandatory to avoid hypovolemia [5]. The average amount of crystalloids used in our study was 16.53 mL · kg1 · hour1 (9.26 to 23.81 mL/kg1/hour1). In the study by Patti and colleagues [11] mean intraoperative fluids given were 19 mL · kg1 · hour1 (range, 5.5 to 36.5 mL/kg1/hour1). In their study, susceptibility of the patients to arrhythmias was increased by fluid overload and the author suggested limited intravenous fluid administration as a way of preventing the arrhythmias, though no explanation was put forward. However, we kept the central venous pressure within normal limits as these patients may be hypovolemic because of low intake of fluids. Hypotensive episodes may be more pronounced when intravascular volume is low before starting mediastinal manipulation.
Study Limitations
The patients with underlying cardiac dysfunctions were excluded from our study because we planned to observe the effects of mediastinal manipulation exclusively. As the hypotension and arrhythmias may be detrimental in cardiac patients, future studies should include such patients. Furthermore, large-scale studies documenting the effects of hemodynamic disturbances occurring during mediastinal manipulation on long-term patient outcome are recommended.
Conclusions
We therefore conclude that during transhiatal esophagectomy the severity of incidence of arrhythmias and hypotension is significant during mediastinal manipulation. Incidence of arrhythmias can be minimized by constant monitoring of vitals, as well as limiting the duration of mediastinal manipulation. However, the incidence of postoperative arrhythmias was insignificant.
| Acknowledgments |
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| References |
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This article has been cited by other articles:
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C. N. Scipione, A. C. Chang, A. Pickens, C. L. Lau, and M. B. Orringer Transhiatal Esophagectomy in the Profoundly Obese: Implications and Experience Ann. Thorac. Surg., August 1, 2007; 84(2): 376 - 383. [Abstract] [Full Text] [PDF] |
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