| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
|
Interact CardioVasc Thorac Surg 2009;8:624-628. doi:10.1510/icvts.2008.189431 © 2009 European Association of Cardio-Thoracic Surgery
Clinical and hemodynamic factors associated with the outcome of early extubation attempts after right heart bypass surgery
a Department of Anesthesiology and Intensive Care, School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan Received 29 July 2008; received in revised form 16 February 2009; accepted 18 February 2009
*Corresponding author. Associate Professor, Intensive Care Division, Department of Anesthesiology and Intensive Care, Kyoto Prefectural University of Medicine, 465 Kajiicho, Kamigyo-ku, Kyoto 602-8566, Japan. Tel.: +81-75-251-5633; fax: +81-75-251-5843.
Fast-track anesthesia with early extubation (EE) is playing an increasingly important role in pediatric cardiac surgery. We examined the pre- and intra-operative factors contributing to successful EE, and outcomes after right heart bypass surgery (RHB). We retrospectively reviewed the medical records of 71 consecutive children (median age=14 months) admitted over a 4-year period to the pediatric intensive care unit (PICU) of our university-based hospital, after RHB. We compared the characteristics and outcomes of 38 children (54%) extubated <3 h, with those of 33 (46%) extubated  3 h after surgery. Odd ratios (OR) and 95% confidence intervals (CI) were calculated. Variables associated with EE included a lower dose of intra-operative fentanyl (OR: 0.95; 95% CI, 0.92–0.99; P=0.03), nitroglycerin (OR: 0.23; 95% CI, 0.07–0.73; P=0.01), and a lower inotropic score (OR: 0.76; 95% CI, 0.61–0.94; P=0.01) on admission. EE was correlated with fewer postoperative respiratory complications (OR: 0.09; 95% CI, 0.02–0.57; P=0.01) and shorter stay in the PICU (OR: 0.88; 95% CI, 0.76–1.03; P=0.12). Our data suggest that EE after RHB could be facilitated in patients with a preserved cardiac function and lower pulmonary vascular resistance. EE could be followed by fewer postoperative pulmonary complications.
Key Words: Early extubation; Fontan operation; Right heart bypass surgery; Postoperative complications
Promoted by advances in the management of cardiopulmonary bypass (CPB) and in operative or anesthetic techniques, fast-track anesthesia with early extubation (EE) is playing an increasingly important role in pediatric cardiac surgery [1, 2]. The early liberation from positive-pressure ventilation was followed by decrease in pulmonary vascular resistance (PVR), and might be associated with improved hemodynamic function after right heart bypass (RHB) surgery [2, 3], and those RHB patients are potential candidates for fast-track anesthesia. In our institution, RHB patients admitted to the pediatric intensive care unit (PICU) are increasingly often extubated early. No clinical study, however, has examined the pre- and intra-operative factors associated with successful EE and postoperative outcomes of those patients. We retrospectively analyzed those variables associated with EE in consecutive pediatric patients after RHB surgery over a 4-year period.
With the approval of our Institutional Review Board, we retrospectively reviewed all the hospital records from consecutive children who, between January 2004 and December 2007, underwent bi-directional cavopulmonary shunt (BCPS) or total-cavopulmonary shunt (TCPC) procedures at the University Hospital of Kyoto Prefectural School of Medicine. Patients who: 1) died during operation; 2) required continuous postoperative extracorporeal cardiopulmonary support beyond the operating room; or 3) were a) >10-year-old; or b) <6-month-old; and 4) underwent a Damus–Kaye–Stansel procedure (DKS) with BCPS simultaneously, were excluded. The patients were divided between 1) a group extubated <3 h (early group, EG) postoperatively; and 2) all others (delayed group, DG). Following cardiac catheterization, all operations were performed by a single surgeon via a median sternotomy and using CPB. Thirteen patients for BCPS and nine for TCPC needed aortic cross-clamping with administration of cardioplegia, and on the beating heart in the remaining patients. A Gore-Tex® roll was used as an extracardiac conduit in TCPC procedures. A fenestration was not systematically performed. The CPB system consisted of non-pulsatile roller pumps and a SAFE-MICRO membrane oxygenator (Senko). The priming solution contained mainly acetated Ringer's solution, and packed red cells, as needed. Chlorpromazine and nitroglycerin were also added. CPB was performed under conditions of moderate hemodilution, maintaining the hematocrit 35–40%, hypothermia to 34–36 °C, and whole body anticoagulation with heparin. The pump flow was controlled to keep a mean arterial pressure 30–50 mmHg. Continuous hemodiafiltration was performed throughout CPB and after CPB for 10–15 min. 2.3. Tracheal intubation and anesthetics The patients were premedicated and intubated through the oral cavity, using an age-adjusted cuffed or non-cuffed tube. Anesthesia was induced with intravenous midazolam, vecuronium, and fentanyl, and maintained with sevoflurane, fentanyl and vecuronium before and after CPB. Midazolam, vecuronium, and fentanyl were added to CPB. The reversal of muscle relaxation was not administered. The choices and doses of anesthetics were ultimately left to the individual anesthesiologist with no formal criteria including the positive attempts for EE. The systemic arterial pressure and central venous pressures (CVP) of the superior vena cavae (SVC) and inferior vena cavae (IVC), the electrocardiogram, pulse oximeter, and capnogram were monitored. The arterial blood was sampled for measurements of blood gases and lactate. No pulmonary artery (PA) or left atrial catheter was used. The patients were transferred to the PICU immediately after surgery, while intubated during either pressure support mode or assist-control mode in pressure-limited ventilation. They were extubated when: 1) they aroused and breathed spontaneously with a) a >5 ml/kg tidal volume, b) a normal respiratory rate for age, and c) <10 cm H2O of ventilator support; 2) SpO2 was >75% after BCPS or >90% after TCPC; 3) they were hemodynamically stable and had a <10 inotropic score [4], dose of [dopamine+ dobutamine+100xepinephrine (µg/kg/min)]; and 4) no major postoperative bleeding was observed, following oxygen administration via a nasal cannula.2.6. Postoperative data collection Cardiorespiratory measurements were made on admission and repeated 12 h later. The following data were also collected: 1) inotropic score [4]; 2) doses administered of a) dopamine, b) dobutamine, c) epinephrine, d) nitroglycerin (µg/kg/min), and e) inhaled nitric oxide; 3) neonatal therapeutic intervention scoring system (N-TISS) [5, 6], measured on the 1st day; 4) urine output during the 1st 24 h; 5) length of a) inotrope therapy, b) nitroglycerin, and c) inhaled nitric oxide, and d) PICU stay. All postoperative respiratory complications, including atelectasis, pneumonia and re-intubation, or other organ dysfunction, occurring in the PICU were recorded. The data are expressed as means±S.D., median [interquartile range (IQR)], or n (%) of observations. The baseline characteristics of both groups of patients were compared using Fisher's exact test for categorical variables, and Student's t-test or Mann–Whitney U-test for continuous variables. Values associated with statistically significant differences in single variable comparisons were entered in a multiple variable logistic regression analysis. Predisposing factors and outcome measures were used for the multiple variable logistic regression. Odd ratios (OR) and 95% confidence intervals (CI) were calculated. Statistical significance was defined as a P<0.05.
3.1. Study groups Among 76 patients screened, two children >10-year-old, and three infants who were <6-month-old and had undergone DKS simultaneously, were excluded. Of the 71 children, 38 (54%) were EG, and 33 (46%) were DG. In DG, five patients required inordinately long periods (144, 144, 200, 264, and 840 h, respectively) of postoperative mechanical ventilation. No significant difference was observed between EG and DG in mean age, body weight, sex distribution, dominant ventricle, complications of hypoplastic left heart syndrome, or patients proportion for BCPS or TCPC (Table 1).
3.2. Factors contributing to early extubation The preoperative measurements during cardiac catheterization are shown in Table 2. The mean PA and IVC pressures were significantly lower in EG than in DG. All other measurements were similar in both groups.
Observations during the surgery are summarized in Table 3. The intra-operative fentanyl dose was significantly lower in EG than in DG, whereas vecuronium dose was similar in both groups. SVC pressure, which reflected the PA pressure after CPB, was lower in EG than in DG. All other intraoperative variables were similar in both groups (Tables 1 and 3).
The hemodynamic measurements and other postoperative observations are shown in Table 4. The inotropic score and N-TISS on PICU admission, SVC pressure both on admission and 12 h later was significantly lower in EG than in DG.
Factors associated with EE by the multiple logistic regression analysis were 1) intra-operative fentanyl dose (OR: 0.95; 95% CI, 0.92–0.99; P=0.03), 2) inotropic score on PICU admission (OR: 0.76; 95% CI, 0.61–0.94; P=0.01), and 3) nitroglycerin dose on PICU admission (OR: 0.23; 95% CI, 0.07–0.73; P=0.01). No patient died in the postoperative period. No significant differences were observed in the short-term hemodynamic parameters between the groups (Table 4). In addition, the first 24 h urinary output was even significantly lower (P=0.03) in EG (3.3±1.3 ml/kg/h) than in DG (4.4± 2.8 ml/kg/h). The duration of inotropic support and nitroglycerin infusion was significantly shorter in EG (Table 5), possibly reflecting the greater initial doses. The incidence of postoperative complications, including 1) pneumonia and atelectasis (8% vs. 45%, P<0.001), 2) organ failure (0% vs. 30%, P<0.001), and 3) re-intubation (3% vs. 21%, P=0.02) was also significantly lower in EG than in DG (Fig. 1). The median duration of mechanical ventilation was 4.75 h shorter (P=0.03), and the median length of PICU stay was 3.0 days shorter (P<0.001) in EG than in DG.
In the multiple logistic regression analysis, the only variable correlated with EE was the occurrence of postoperative pulmonary complications (OR: 0.09; 95% CI, 0.02–0.57; P=0.01). This relation was confirmed after the exclusion of five patients who required inordinately lengthy postoperative ventilatory support and nine patients with inotropic score >10 on PICU admission (data not shown). The length of PICU stay tended to be shorter in EG (OR: 0.88; 95% CI, 0.76–1.03; P=0.12), suggesting that EE may indeed be correlated with improved postoperative outcomes in RHB patients.
In this study, we identified several variables related to EE, or associated with its outcome, in RHB pediatric patients. Patients who were successfully extubated early had a lower incidence of postoperative pulmonary complications, organ dysfunctions, and a shorter PICU stay. On the other hand, postoperative short-term hemodynamics were not affected by the EE. A poor intra- and postoperative cardiac function and higher PVR, reflected by the perioperative requirement of large doses of inotropes and vasodilators, negatively affected the ability to extubate early. The anesthesia strategy, with lower dose of fentanyl, might be a factor contributing to successful EE. Although several reports have recently addressed the significance of fast-track anesthesia with EE after congenital heart surgery [2, 7], the term of EE may be undefined. On average, up to 3–8 h after surgery in the operating room or PICU is reported as the time period for EE, including neonatal study [2, 3, 8]. Given the time of 3 h for the stabilization after arriving at PICU and preparation of extubation, we considered this time period as an appropriate cut-off. This strategy was implemented safely in a variety of pediatric populations, including patients at high risk of pulmonary hypertension [2]. In RHB patients, the early liberation from positive-pressure ventilation might facilitate the decrease in PVR, directly increasing the cardiac output [3]. Concerns persist, however, with respect to the respiratory or hemodynamic compromise associated with EE. Hypercarbia, hypoxemia and the development of atelectasis, possibly attributable to EE attempts, might increase the risk of high PVR and circulatory failure [8, 9]. Moreover, weaning from mechanical ventilation might induce myocardial ischemia or precipitate heart failure in patients with limited cardiac reserves [9]. No clinical study has directly examined the value of EE after RHB surgery. In this study, we observed no significant short-term improvement in hemodynamic function after extubation, in contrast to earlier case reports [3]. A decrease in PVR associated with the early discontinuation of positive-pressure ventilation had no clinically significant effects. Patients with depressed ventricular function and requiring greater inotropic support (inotropic score >10) were excluded from our current EE criteria, as cardiac dysfunction is the main factor determining the postoperative hemodynamics and clinical course [7, 9, 10]. EE was associated with a lower incidence of postoperative pulmonary complication and could become a predictor of improved postoperative pulmonary outcome from this retrospective analysis. Mechanical ventilation is an important source of ventilator-associated pneumonia [11] or lung injury [12] even short-term including during anesthesia [13]. Our results therefore might suggest that a difference of 4–5 h in ventilator time affected ventilator-associated complications. Furthermore, a shorter ventilator period with fewer respiratory complications might significantly shorten the PICU stay and, perhaps, lower medical costs [8]. Anesthesia is an important variable associated with a successful EE. Previous studies have suggested that the use of <5–15 µg/kg of fentanyl with volatile anesthetics, can be safely administered in fast-track surgery [1, 8]. Although the use of higher doses of narcotics was found in earlier studies to prominently lower the perioperative stress and improve the postoperative outcomes of pediatrics after congenital heart surgery [14], this was not confirmed in more recent studies [2]. No significant increase in intraoperative instability of hemodynamics and postoperative complications attributable to lower narcotic doses was observed in our study.
The implications of this study are limited by its retrospective, observational design. The significance of EE should be further ascertained by means of randomized clinical trials, in which an official fast-track anesthesia and postoperative management protocol is implemented [8, 10]. In addition, the efficacy of remifentanil, an ultra-short acting narcotic, which was clinically unavailable at the time of this study, would be worth evaluating as a promising alternative to fentanyl [10, 15]. Shorter ventilator times, including extubation in the operating room, should also be studied. In summary, we extubated over 50% of young children at <3 h after RHB surgery, and EE may be a predictor of improved postoperative outcomes. Prospective randomized studies might be considered focusing on the assessment of EE as an intervention to decrease the postoperative pulmonary complications, including in patients with poor perioperative cardiac function, or a protocol-guided management of anesthesia, with specific attention to the selections or doses of narcotics, suggested as <30 µg/kg fentanyl in this study.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
Top
Abstract
1. Introduction
P=0.02 vs. the delayed group.