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© 2002 European Association of Cardio-Thoracic Surgery
Immediate postoperative extubation after minimally invasive direct coronary artery surgery (MIDCAB)
a Department of Cardiovascular Surgery, University of Kiel, Arnold Heller Str. 7, 24105 Kiel, Germany
* Corresponding author. Tel.: +49-431-597-4400; fax: +49-431-597-4402 Received March 11, 2002; received in revised form July 20, 2002; accepted July 22, 2002
We were interested whether immediate postoperative extubation and early discharge of the intensive care unit (ICU) is safe in minimally invasive direct coronary artery surgery (MIDCAB) patients. Therefore we retrospectively analyzed the data from 217 patients undergoing MIDCAB from 2/99 to 4/02. Immediate postoperative extubation was possible in 182/217 (83.9%) with eight patients needing reintubation (11.5±3.3 h). Ventilation time of the remaining 35 patients was less than 24 h in 31 patients (8.8±5.3). Sixty-nine patients (31.8%) were directly transferred from the ICU. Immediate extubation after MIDCAB surgery is safe resulting in an effective use of resources.
Key Words: Minimally invasive direct coronary artery surgery (MIDCAB); Fast track; Coronary artery bypass
Minimally invasive coronary artery bypass grafting (MIDCAB) has become an accepted technique for revascularization of the left anterior descending artery (LAD). This technique is less invasive in terms of surgical trauma and activation of inflammatory response resulting in advanced patient recovery compared to conventional approaches using cardiopulmonary bypass [1,2]. Nevertheless the majority of centers maintain standard perioperative treatment strategies including postoperative mechanical ventilation for MIDCAB patients. With the background of limited intensive care unit (ICU) capacities we were interested in ‘fast track recovery’ aiming for immediate postoperative extubation. Trying to address this aspect we present our experience with immediate postoperative extubation in 217 consecutively operated patients with MIDCAB technique from 2/99 to 4/02.
We retrospectively analyzed 217 consecutive patients undergoing MIDCAB operation between 2/99 and 4/02 in our center after introduction of immediate postoperative extubation. The preoperative cardiac findings of these 217 patients (158 males, 59 females, mean age 62.7±10.4 years; range 35–87 years; body mass index (BMI) 27.3±4.22 kg/m2) are comprised in Table 1. Along with increasing experience more patients with severe comorbidities and multivessel disease were accepted for MIDCAB procedure because alternative procedures (conventional coronary artery bypass grafting, CABG; off-pump coronary artery bypass, OPCAB; interventional means) were assumed to be more hazardous (Table 2: comorbidities).
2.1. Data analysis Data were received by retrospective analysis of the complete patient charts. Data analysis was performed by SPSS, Version 8.0. Univariate comparison between immediate extubated, non-extubated or reintubated patients was performed for different variables (P-values <0.05 were considered statistically significant). 2.2. Anesthesiological management Anesthesia was performed as total intravenous anesthesia. Premedication consisted of 5–10 mg nitrazepam overnight and midazolam (3.75–7.5 mg) preoperatively. Anesthesia was induced with Remifentanyl (0.5 µg/kg per min) for 2 min, followed by continuous infusion (0.25 µg/kg per min). Maintenance anesthesia was continued with propofol (0.12 mg/kg per min). For muscle relaxation one dose of cis-Atracurium 0.15 mg/kg for intubation, followed by repetitive doses of 0.02 mg/kg was given. For reduction of the sympathic response a bolus of clonidin (0.15 mg) was combined with subsequent continuous infusion (0.25 µg/kg per h).Hypertension was controlled by Glyceroltrinitrat, starting at a dosage of 1 µg/kg per min, tachycardia by application of esmolol (10 mg). Intraoperative monitoring included electrocardiograph with ST-segment analysis, continuous arterial blood pressure measurements, Swan-ganz-catheter, intermittent blood gas analyzes and measurements of body temperature. Ventilation was performed as single lung ventilation. Anesthesia was gradually reduced and terminated during closure of the chest wound. The analgetic regimen consisted of 1 g metamizol infusion and 1 g paracetamol given after intubation combined with either intrapleural application of ropivacain, intercostal nerve blockage with ropivacain or patient controlled analgesia pump (PCA) with piritramid. For pain management with intrapleural catheters Ropivacain was administered as intrapleural bolus application (225 mg) every 4 h up to 36 h. PCA-infusion was extended for a maximum of 36 h postoperatively (2 mg bolus; maximal 45 mg/12 h). The systematic evaluation of the different postoperative pain treatment protocols was part of another study [3]. Normothermia of the patient was secured by increasing the operating-room temperature, positioning of the patient on a heating mattress and enwrapping one leg with a heat retentive drape. Contraindications for immediate postoperative extubation were: congestive heart failure combined with general contraindications, core temperature below 35°C, inadequate spontaneous ventilation (oxygen saturation less 95%, pCO2 tension >50 mmHg, low tidal volumes, respiratory rate >20 breaths/min). 2.3. Surgical technique All patients underwent surgery by use of a standard technique as described by Cremer et al. earlier [4].
The MIDCAB procedure could be completed in all 217 consecutive patients (operation time 105.04±19.6 min) without any conversion. All patients left the operating room in hemodynamically stable condition, one patient with support of an intraaortic balloon pump, which was already implanted preoperatively due to an acute myocardial infarction. Of these 217 patients immediate postoperative extubation was performed in 182 (83.9%) patients. The demographic data of this group were similar to the data of the entire study group. Age ranged from 38 to 81 years (62.3±9.8 years) with 43/182 (23.6%) patients having a BMI >30 kg/m2. Moderate to severe reduced left ventricular function was present in 18/182 (9.8%) patients, with 25.8% (47/182) of the patients, respectively 9.9% (18/182) having two and three vessel disease. Chronic obstructive pulmonary disease (COPD) was present in 12/182 patients (6.6%). Comparing preoperative demographic data like the presence of chronic obstructive pulmonary disease, renal insufficiency, body mass index >30 kg/m2 or left ventricular function <30% a significant difference could be only assessed for the reduced ventricular function between the immediate extubated and the non-extubated patients (  ). Of the 182 immediately extubated patients eight (4.3%) had to be reintubated due to respiratory insufficiency within the first postoperative hour after arrival on the ICU. The mean duration of subsequent ventilation time was 11.5±3.3 h. No preoperative demographic data could be ruled out as a specific risk factor for reintubation. Two additional patients had to be reintubated for surgical reexploration due to bleeding. The residual 35 patients were not directly extubated in the operating room due to different reasons. In these patients a tube for non-selective ventilation replaced the double-lumen tube. Of this group 31 patients were ventilated less than 24 h (8.8±5.3 h). In four patients a prolonged ventilation of more than 72 h was necessary. The particular reasons in this patients were significant obesity with intubation trauma followed by glottis edema and consecutive pseudomonas pneumonia (ventilation time 3 weeks), hemodynamic instability due to intermittent atrial fibrillation and pulmonary hypertension in a 81 year old patient with ischemic cardiomyopathy (ventilation time 3 days), hemodynamic instability with preoperative implantation of an intraaortic balloon pump due to acute myocardial infarction in a 83 year old patient (patient died after diffuse bleeding in multi-organ failure) and a 66 year old woman with recurrent respiratory decompensations (ventilation time 7 days). Postoperative in hospital complications included intubation trauma in 2 of 217 patients, hemiplegia three days postoperatively in one patient with reduced left ventricular function and atrial fibrillation, myocardial infarction by enzymatic values without hemodynamic instability in another patient, atrial fibrillation in eight patients and pulmonary artery embolism in two patients. Three patients died in early follow up one as declared former and two after resuscitation of unknown reason (postmortem showed an open LAD-bypass in one patient and hematothorax with an injured ima in the second patient). Sixty-nine (31.8%) patients of the whole group were transferred to the regular ward on the day of surgery, 133 patients (61.2%) spent 1 day on the ICU, nine (4.1%) 2 days due to a reduced transfer rate at the weekend. Six patients required prolonged intensive care treatment. None of the directly transferred patients required readmission to the ICU for respiratory failure. In another subgroup (40 patients) of the entire cohort, published by Behnke et al. [3], the Aldrete score [5] was applied to evaluate whether the individual patient was in an adequate condition for discharge from the ICU (score >9). According to this 80% of the patients met the criteria of this score after 1.4±0.65 h.
Routine early or even immediate extubation after conventional CABG procedure has been introduced earlier by singular groups, but never became a common strategy [6,7]. Along with the favorable specifics of MIDCAB grafting like reduced surgical trauma including small incision and avoidance of extracorporal circulation short ventilation times, reduced length of stay in the ICU and early discharge from the hospital could already be realized. But nevertheless immediate extubation has not been discussed extensively so far. In contrast many groups still perform a postoperative standard treatment with 4–10 h postoperative ventilation in MIDCAB patients too [8,9]. The potential benefits of immediate postoperative extubation focus on the one hand on medical aspects [10,11] and on the other hand on logistic aspects dealing with ICU capacities and reimbursement policies. Thus, early discharge from the ICU on the day of surgery may expand the utilization of the existing ICU capacity effectively. However, adequate safety has to be provided for every patient. As shown in an earlier MIDCAB collective the 30-day mortality summed up to 1% and was limited to patients with additional risks for conventional bypass grafting [4]. Regarding reported graft patency rates from 94 to 98%, MIDCAB surgery is a safe technique [12,13]. Under these conditions we were interested in applying immediate postoperative extubation in our MIDCAB cohort. The retrospective analysis of our consecutive 217 MIDCAB patients operated by one surgeon assessed that immediate postoperative extubation could be successfully performed in 83.9% (182/217) of patients. An important feature for this concept was the modification of the complete anesthesiological management from high dose opioid technique to a short acting opioid plus intravenous propofol anesthesia as well as keeping patient's body temperature above 35°C. Of the directly postoperatively extubated patients 4.3% (8/182) had to be reintubated after a short period. This could be explained by an inefficient postoperative analgetic regime followed by an opioid overdose or inadequate awareness of the patient with consecutive respiratory failure. Consequently the pain management was changed from intravenous opiod application to local anesthesia (intercostal nerve blockage or intrapleural infusion). With this ultimate modification the rate of early reintubation could be dramatically reduced. Despite elaboration of a standardized protocol for safe immediate extubation after MIDCAB grafting 35 patients could not be directly extubated. That was not only the result of precautions taken for particular patients with a generally reduced health status but also the effect of management failures like prolonged anesthesia with consecutive respiratory insufficiency or low body temperature in singular patients. Regarding the ventilation time in this group 31 patients remained intubated less than 24 h with a mean ventilation time of 8.8±5.3 h. In the four remaining patients prolonged ventilation more than 72 h was necessary due to specific complications as declared former. After MIDCAB procedure 32% of the patients were transferred to the regular ward at the day of operation. None of these patients required readmission to the ICU. As the decision for early transfer was not stratified, e.g. by applying a score system, this percentage does not accurately reflect the maximal number of transferable candidates. However in a subgroup of 40 patients in our collective, it could be demonstrated that after 1 h approximately 80% of patients were in a stable health condition according to the Aldrete score allowing a safe transfer to the regular ward [3]. It is an important economic aspect not only to perform immediate postoperative extubation but also to consequently intend early transfer from the ICU, thus providing expanded ICU-bed capacities allowing for optimized ICU utilization. MIDCAB procedures in our institution are preferably scheduled for the day's first position enabling the reutilization of the same ICU bed for another patient at the same day on the base of an acceptable stable health condition of the MIDCAB patient. Based on our data we conclude that immediate postoperative extubation after MIDCAB procedures is an attractive and safe option in the majority of these patients, performing not only minimally invasive surgery, but also minimally invasive perioperative medical treatment. Therefore coronary artery surgery can be managed in uncomplicated surgical patients as ‘non-intensive care‘ surgery, comparable to other revascularization techniques like percutaneous coronary angioplasty (PTCA) or stent grafting. This can be used as an important factor for reorganization of the ICU aiming at major cost savings and a more efficient use of capacity. One major limitation of the study is the retrospective design. Another limitation is that the score system (Aldrete score) was not applied prospectively in all patients. But our intention was just to demonstrate the safety and feasibility of the fast track concept for our MIDCAB patients and as shown in this subgroup the rate of potential candidates for early transfer from the ICU is much higher than the actually performed transfers. Thus we intensify the fast-track regimen for our MIDCAB patients and the planning of operation- and ICU-capacities is based in routine patients on this concept.
ICVTS on-line discussion Author: Stephen Large, Department of Surgery, Papworth Hospital, Cambridge CB3 8RE, UK Date: 07-Aug-2002 18:46 Message: An interesting paper but, with a will, perhaps patients on bypass could also be extubated equally early after surgery. There is a desperate need for a multicentre randomised trial of eligible patients for on- or off-pump revascularistaion. Author: Dr. Augustine Tang, Division of Cardiovascular Surgery, Department of Surgery, Toronto General Hospital, Elizabeth Street, Toronto, M5G 2C4, Canada Date: 09-Aug-2002 13:58 Message: The data in this manuscript serves to illustrate that the authors had selected their retrospective cohort well for early extubation following MIDCAB. However, this is not entirely helpful for the readership as there is relatively little detail in the text to indicate exactly how this selection was done. Phrases like ‘general health status as contraindications’ and ‘not meeting the criteria for a variety of reasons’ failed to enable readers to grasp the practical aspects of this concept. In the comments section, the authors stated that even those patients with comorbidities such as COPD, previous stroke and poor LV function managed to avoid reintubation following this protocol whilst others either failed or were excluded. They should clarify what factors might have separated these cohorts. If this involved more of an art than science, again they should state this. Otherwise, the authors should be congratulated on their achievement in this clinical series! Author: Dr. Pascal Schroeyers, Dept. of Cardiac Surgery, H-Hart Ziekenhuis, Wilgenstraat 2, Roeselaere, Belgium Date: 10-Aug-2002 16:02 Message: Many goals of MIDCAB grafting like reduced surgical trauma, avoidance of CPB, short ventilation times, reduced ICU and hospital stay and fast track to rehabilitation have already been reported and discussed elsewhere. However, for most cardiac centers in Europe, routine immediate postoperative extubation and early discharge from ICU on the day of surgery never became a common strategy. S. Fraund and colleagues adopted this policy with adequate safety, in order to improve the utilization of the existing ICU capacity effectively. To achieve an almost 84% successful immediate extubation, they had to modify their complete anesthesiological management from a high dose opioid technique to short activity opioid plus intravenous propofol anesthesia. However, 4.3% of these patients had to be reintubated after a short period. Inefficient postoperative analgetic regime followed by an opioid overdose with consecutive respiratory failure was in most cases the trigger cause for reintubation. Furthermore, only 32% of all patients undergoing the MIDCAB procedure were transferred to a regular ward on the day of operation. In contrast with many groups, immediate postoperative extubation is being used in a wider range of procedures in our hospital. Immediate extubation is performed after video-assisted MIDCAB, closed chest transabdominal video-assisted OPCAB or short procedures like minimally invasive video-assisted ASD closure. Anesthesia is induced in our patients with a short action opioid (Remifentanyl) followed by continuous infusion. Sevoflurane is added for its myocardium protection effect. A peridural catheter, with continuous infusion of levobupivacaine, is used in all patients for PCEA, placed 12 hours before surgery and removed 24 to 36 hours after surgery. Using this standard anesthesiological management, none of our patients had to be reintubated and early discharge from ICU was achieved in all patients. To our knowledge, neurological complications after anesthesiological management using peridural catheter for MICS procedures have not (yet) been reported. PII: S1569929302000154
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Abstract
1. Introduction
