Ricardo Munoz

Use of dexmedetomidine in children after cardiac and thoracic surgery.

Objective: In this report, we describe our experience with the use of dexmedetomidine in spontaneously breathing as well as in mechanically ventilated patients, after congenital cardiac and thoracic surgery. Design: Retrospective case series. Setting: University hospital, pediatric cardiac intensive care unit. Patients: Thirty-three spontaneously breathing and five mechanically ventilated patients who received dexmedetomidine after cardiothoracic surgery. Interventions: None. Measurements and Main Results: Thirty-eight patients, age 8 ± 1.1 yrs old and weight 29 ± 3.8 kg, were included. Seven patients (18%) were <1 yr old. Dexmedetomidine was used as a primary sedative and analgesic agent, and when its effect was considered inadequate, despite incremental infusion doses, a rescue agent was administered. The initial dexmedetomidine infusion dose was 0.32 ± 0.15 &mgr;g/kg/hr followed by an average infusion of 0.3 ± 0.05 &mgr;g/kg/hr (range 0.1–0.75 &mgr;g/kg/hr). There was a trend toward higher dexmedetomidine infusion requirement in patients <1 yr old compared with older children, 0.4 ± 0.13 vs. 0.29 ± 0.17 &mgr;g/kg/hr (p = .06). Desired sedation and analgesia were achieved during 93% and 83% of the dexmedetomidine infusion, respectively. According to the intensive care unit sedation scale (score 0–3) and two pain scales (Numeric Visual Analog Scale and Face, Legs, Activity, Cry, and Consolability, score 0–10), the mean sedation score was 1.3 ± 0.6 (mild sedation) and the mean pain score was 1.5 ± 0.9 (mild pain). The most frequently rescue drugs administered were fentanyl, morphine, and midazolam. Overall, 49 rescue doses of sedatives/analgesics were given. Patients <1 yr old required more rescue boluses than older children, 22 boluses (3.19 ± 0.8) vs. 27 boluses (0.8 ± 0.2, p = .003). Throughout the dexmedetomidine infusion there was no significant change in the systolic and diastolic blood pressure trend. Six patients (15%) had documented hypotension. In three, hypotension resolved with decreasing the dexmedetomidine infusion dose whereas in the other three, hypotension resolved after discontinuing the infusion. Although there was a trend toward lower heart rates, this was not clinically significant. One patient had an episode of considerable bradycardia without hypotension, which resolved shortly after discontinuing the dexmedetomidine infusion. No significant changes in the arterial blood gases or respiratory rates were observed. There was no mortality, and the total intensive care unit length of stay was 19 ± 2 hrs. Conclusions: Our data suggest that dexmedetomidine is a well-tolerated and effective agent for both spontaneously breathing and mechanically ventilated patients following congenital cardiac and thoracic surgery.

Changes in whole blood lactate levels during cardiopulmonary bypass for surgery for congenital cardiac disease: An early indicator of morbidity and mortality ☆ ☆☆ ★

OBJECTIVE Our objective was to evaluate the change in lactate level during cardiopulmonary bypass and the possible predictive value in identifying patients at high risk of morbidity and mortality after surgery for congenital cardiac disease. METHODS We prospectively studied lactate levels in 174 nonconsecutive patients undergoing cardiopulmonary bypass during operations for congenital cardiac disease. Arterial blood samples were taken before cardiopulmonary bypass, during cardiopulmonary bypass (cooling and rewarming), after cardiopulmonary bypass, and during admission to the cardiac intensive care unit. Complicated outcomes were defined as open sternum as a response to cardiopulmonary instability, renal failure, cardiac arrest and resuscitation, extracorporeal membrane oxygenation, and death. RESULTS The largest increment in lactate level occurred during cardiopulmonary bypass. Lactate levels decreased between the postbypass period and on admission to the intensive care unit. Patients who had circulatory arrest exhibited higher lactate levels at all time points. Nonsurvivors had higher lactate levels at all time points. A change in lactate level of more than 3 mmol/L during cardiopulmonary bypass had the optimal sensitivity (82%) and specificity (80%) for mortality, although the positive predictive value was low. CONCLUSIONS Hyperlactatemia occurs during cardiopulmonary bypass in patients undergoing operations for congenital cardiac disease and may be an early indicator for postoperative morbidity and mortality.

Dexmedetomidine : A Novel Drug for the Treatment of Atrial and Junctional Tachyarrhythmias During the Perioperative Period for Congenital Cardiac Surgery: A Preliminary Study

BACKGROUND: Atrial and junctional tachyarrhythmias occur frequently during the perioperative period for congenital cardiac surgery and can be a cause of increased morbidity and mortality. These rhythm disturbances that may be well tolerated in a normal heart can cause significant hemodynamic instability in patients with congenital heart defects, particularly during the postcardiopulmonary bypass period. Management of these arrhythmias presents more of a challenge, since currently available antiarrhythmic drugs can be ineffective and poorly tolerated. In this study, we examined the possible effect of dexmedetomidine, a primarily sedative drug, on atrial and junctional tachyarrhythmias. Though some animal data have shown that it can prevent certain types of ventricular tachycardia, its therapeutic role during these types of arrhythmias has not been studied. METHODS: This was a retrospective, nonrandomized, noncontrolled study. Fourteen patients admitted to the cardiac intensive care unit and who received dexmedetomidine for both, sedation/analgesia and for junctional ectopic tachycardia (JET), atrial ectopic tachycardia (AET), reentry type supraventricular tachycardia (Re-SVT), atrial flutter (AF) or junctional accelerated rhythm (JAR) were included. Dexmedetomidine was used as a primary drug or as a rescue if other antiarrhythmics had been used. Our primary end-points were (a) conversion to normal sinus rhythm (NSR) within 3 min for Re-SVT, and 2 h for all other arrhythmias or (b) heart rate (HR) reduction to improve hemodynamics; JET ≤170 bpm, AET ≥20%, AF ≤150 bpm and for JAR prevention of progression to JET. RESULTS: The mean age and weight were 2 ± 3 mo and 4 ± 1.5 kg, respectively. Most of the arrhythmias (79%) occurred during the postoperative period. Dexmedetomidine was used as a primary treatment in nine and as a rescue in five patients. Ten patients (71%) received an initial loading dose of 1.1 ± 0.5 &mgr;g/kg. A continuous infusion, 0.9 ± 0.3 &mgr;g · kg−1 · h−1 was administered in 12 patients. Thirteen patients’ lungs were mechanically ventilated. Adverse effects were seen in four patients (28%). Three had hypotension that responded to fluid administration and one had a possible brief complete atrioventricular (AV) block. Nine of the 14 patients were transiently paced with atrial (seven) or AV sequential (two) pacing to improve AV synchrony. The primary outcome with rhythm and/or HR control was achieved in 13 patients (93%). JET rate decreased from 197 ± 22 to 165 ± 17 bpm within 67 ± 75 min of dexmedetomidine administration. Five of these patients converted to NSR in 39 ± 31 h and one remained in JAR. All four patients with Re-SVT had resolution of their tachyarrhythmia. Three converted to NSR and one to JAR. One patient with AET (220–270 bpm) responded well with decreasing HR to 120 bpm within 35 min and to NSR in 85 min. One patient with AF failed to respond. In two patients with JAR, neither progressed to JET and HR decreased from 158 ± 11 to 129 ± 1 bpm. CONCLUSION: This preliminary, observational report suggests that dexmedetomidine may have a potential therapeutic role in the acute phase of perioperative atrial and junctional tachyarrhythmias for either HR control or conversion to NSR.

Perioperative Use of Dexmedetomidine Is Associated With Decreased Incidence of Ventricular and Supraventricular Tachyarrhythmias After Congenital Cardiac Operations

BACKGROUND Postoperative tachyarrhythmias remain a common complication after congenital cardiac operations. Dexmedetomidine (DEX), an α-2 adrenoreceptor agonist, can have a therapeutic role in supraventricular tachyarrhythmias for cardioversion to sinus rhythm or heart rate control. Whether routine perioperative use of DEX decreases the incidence of supraventricular and ventricular tachyarrhythmias was studied. METHODS In this prospective cohort study, 32 pediatric patients undergoing cardiothoracic operations received DEX and were compared with 20 control patients who did not receive DEX. RESULTS Dexmedetomidine was started after anesthesia induction and continued intraoperatively and postoperatively for 38±4 hours (mean dose, 0.76±0.04 μg/kg/h). Ten control patients and 2 DEX patients sustained 16 episodes of tachyarrhythmias (p=0.001), including a 25% vs 0% (p=0.01) incidence of ventricular tachycardia and 25% vs 6% (p=0.05) of supraventricular arrhythmias in the control and DEX group, respectively. Transient complete heart block occurred in 2 control patients and in 1 DEX patient. Control patients had a higher heart rate (141±5 vs 127±3 beats/min, p=0.03), more sinus tachycardia episodes (40% vs 6%; p=0.008), required more antihypertensive drugs with nitroprusside (20±7 vs 4±1 μg/kg; p=0.004) and nicardipine (13±5 vs 2±1 μg/kg; p=0.02), and required more fentanyl (39±8 vs 19±3 μg/kg; p=0.005). CONCLUSIONS Perioperative use of dexmedetomidine is associated with a significantly decreased incidence of ventricular and supraventricular tachyarrhythmias, without significant adverse effects.

Dexmedetomidine as the primary sedative during invasive procedures in infants and toddlers with congenital heart disease

Objective: In this report, we describe the use of dexmedetomidine as the primary sedative agent while performing invasive procedures in infants and toddlers with congenital heart disease who are breathing spontaneously. Design: Retrospective case review. Setting: University Hospital, pediatric cardiac intensive care unit. Patients: Six spontaneously breathing children, five infants and one toddler, all with congenital heart disease, who received dexmedetomidine as the primary sedative agent while undergoing an invasive procedure. Interventions: None. Measurements and Main Results: Six patients with congenital heart disease, age 3 days–29 months were included. Five of the patients were <6 months of age. Each patient underwent an invasive procedure including central venous line placement, chest tube insertion, fiberoptic bronchoscopy, and femoral cut-down for Broviac placement. All patients were breathing spontaneously throughout their procedure. Dexmedetomidine was used as the primary sedative agent during the procedure with additional sedation provided with low dose ketamine for patient movement in three of the six patients. The average dexmedetomidine dose used was 1.5 &mgr;g/kg (1–3 &mgr;g/kg). An additional low dose of ketamine, 0.7 mg/kg (0.3–1.5 mg/kg), was used in 50% of the patients. All patients breathed spontaneously without significant desaturation throughout the procedure, and although there was a trend toward lower blood pressure and heart rate, all patients remained warm and well perfused. Each of the six procedures was successfully completed without any associated complications. Conclusions: Our experience suggests that invasive procedures can be successfully performed in spontaneously breathing infants and toddlers with congenital heart disease using dexmedetomidine alone or in combination with low dose ketamine.

Dexmedetomidine use in a pediatric cardiac intensive care unit: can we use it in infants after cardiac surgery?

Objective: To assess clinical response of dexmedetomidine alone or in combination with conventional sedatives/analgesics after cardiac surgery. Design: Retrospective study. Setting: Pediatric cardiac intensive care unit. Patients: Infants and neonates after cardiac surgery. Measurements and Main Results: We identified 80 patients including 14 neonates, at mean age and weight of 4.1 ± 3.1 months and 5.5 ± 2 kg, respectively, who received dexmedetomidine for 25 ± 13 hours at an average dose of 0.66 ± 0.26 &mgr;g·kg−1·hr−1. Overall normal sleep to moderate sedation was documented 94% of the time and no pain to mild pain for 90%. Systolic blood pressure (SBP) decreased from 89 ± 15 mm Hg to 85 ± 11 mm Hg (p = .05), heart rate (HR) from 149 ± 22 bpm to 129 ± 16 bpm (p < .001), and respiratory rate (RR) remained unchanged. When baseline arterial blood gases were compared with the most abnormal values, pH decreased from 7.4 ± 0.07 to 7.37 ± 0.05 (p = .006), Po2 from 91 ± 67 mm Hg to 66 ± 29 mm Hg (p = .005), and CO2 increased from 45 ± 8 mm Hg to 50 ± 12 mm Hg (p = .001). At the beginning of the study, 37 patients (46%) were mechanically ventilated; and at 48 hours, 13 patients (16%) were still intubated and five patients failed extubation. Three groups of patients were identified: A, dexmedetomidine only (n = 20); B, dexmedetomidine with sedatives/analgesics (n = 38); and C, dexmedetomidine with both sedatives/analgesics and fentanyl infusion (n = 22). The doses of dexmedetomidine and rescue sedatives/analgesics were not significantly different among the three groups but duration of dexmedetomidine was longer in group C vs. A (p = .03) and C vs. B (p = .002). Pain, sedation, SBP, RR, and arterial blood gases were similar. HR was higher in group C vs. B (p = .01). Comparison between neonates and infants showed that infants required higher dexmedetomidine doses, 0.69 ± 25 &mgr;g·kg−1·hr−1, and vs. 0.47 ± 21 &mgr;g·kg−1·hr−1 (p = .003) and had lower HR (p = .01), and RR (p = .009), and higher SBP (p < .001). Conclusions: Dexmedetomidine use in infants and neonates after cardiac surgery was well tolerated in both intubated and nonintubated patients. It provides an adequate level of sedation/analgesia either alone or in combination with low-dose conventional agents.

Magnesium supplementation during cardiopulmonary bypass to prevent junctional ectopic tachycardia after pediatric cardiac surgery: A randomized controlled study

OBJECTIVES We analyzed the role of magnesium sulfate (MgSO(4)) supplementation during cardiopulmonary bypass in pediatric patients undergoing cardiac surgery, assessing the incidence of hypomagnesemia and the incidence of junctional ectopic tachycardia. METHODS We performed a randomized, double-blind, controlled trial in 99 children. MgSO(4) or placebo was administered during the rewarming phase of cardiopulmonary bypass: group 1, placebo group (29 patients); group 2, 25 mg/kg of MgSO(4) (30 patients); and group 3, 50 mg/kg of MgSO(4) (40 patients). RESULTS At the time of admission to the cardiac intensive care unit, groups receiving MgSO(4) had significantly greater levels of ionized magnesium (group 1, 0.51 + or - 0.07; group 2, 0.57 + or - 0.09; group 3, 0.59 + or - 0.09). Hypomagnesemia before bypass was common (75%-86.2%) and not significantly different among the groups. The proportion of hypomagnesemia decreased significantly at admission to the cardiac intensive care unit in groups receiving MgSO(4) (group 1, 77.8%; group 2, 63%; group 3, 47.4%). Patients receiving placebo (group 1) had a significantly greater occurrence of junctional ectopic tachycardia than groups receiving MgSO(4) (group 1, n = 5 [17.9%]; group 2, n = 2 [6.7%]; group 3, n = 0 [0%]). Age (<1 month), Aristotle score (>4), and history of cardiac failure were associated with junctional ectopic tachycardia. None of the patients with those characteristics in group 3 had junctional ectopic tachycardia. No association was found between study groups and the Pediatric Risk of Mortality score or length of stay in the cardiac intensive care unit. CONCLUSIONS Supplementation with MgSO(4) during cardiopulmonary bypass seems to reduce the incidence of hypomagnesemia and junctional ectopic tachycardia at admission to the cardiac intensive care unit. This effect seems to be dose related.

The association of renal dysfunction and the use of aprotinin in patients undergoing congenital cardiac surgery requiring cardiopulmonary bypass.

BACKGROUND: The use of large-dose aprotinin during cardiopulmonary bypass (CPB) in adult patients has been linked to postoperative renal dysfunction, but its effect on the pediatric population undergoing complex congenital cardiac operations is not well defined. METHODS: We used a retrospective cohort analysis to evaluate children undergoing cardiac surgery requiring CPB between July 2004 and July 2006. Demographic data and surgical risk quantified by the Aristotle surgical complexity level were analyzed as covariates. Renal dysfunction was defined according to the RIFLE criteria, an international consensus classification which defines three grades of increasing severity of acute kidney injury: risk (Class R), injury (Class I), and failure (Class F) based on serum creatinine values. A univariate and multivariate logistic regression analysis and a propensity score were used to analyze the data. The propensity score was developed using pretreatment covariates associated with the administration of aprotinin. A multivariate logistic regression was then used with the propensity score and intraoperative measures as covariates. A P value <0.05 was considered statistically significant. RESULTS: Among 395 patients who underwent cardiac surgery, 55% received aprotinin and 45% did not. Thirty-one percent of the cohort had previous cardiac surgery; 17% were neonates. According to the RIFLE criteria, 80 of the patients (20.3%) had acute kidney injury in the postoperative period; 53 (13.4%) had risk of renal dysfunction with 23 (5.8%) having injury and four patients (0.7%) having failure. Those receiving aprotinin had a higher incidence of previous cardiac surgery (54.1% vs 5%), sepsis (6.9% vs.0.0%), heart failure (24.8% vs 12.4%), mechanical ventilation (25.2% vs 2.8%), or mechanical circulatory support (6.0% vs.0.6%). More patients had an Aristotle level of 4 (26.6% vs 2.8%) and were treated with diuretics (63.8% vs 26.6%), angiotensin converting enzyme inhibitors (21.1% vs 7.9%), milrinone (25.7% vs 4.5%), and inotropic support (16.1% vs 2.3%). Although there was a significant difference in the unadjusted risk of renal dysfunction, adjustment with the preoperative propensity score revealed that there was no association between aprotinin and renal dysfunction (OR 1.32; 95% CI 0.55–3.19). The duration of CPB was the only independent variable associated with the development of renal dysfunction (OR 1.0; 95% CI 1.009–1.014). CONCLUSIONS: Patients who receive aprotinin are more likely to present with preoperative risk factors for the development of postoperative renal dysfunction. However, when associated risk factors are properly considered, the use of aprotinin does not seem to be associated with a higher risk of developing renal dysfunction in the immediate postoperative period in children.

Short- and intermediate-term survival after extracorporeal membrane oxygenation in children with cardiac disease

OBJECTIVES In children with cardiac disease, common indications for extracorporeal membrane oxygenation (ECMO) include refractory cardiopulmonary resuscitation (E-CPR), failure to separate from cardiopulmonary bypass (OR-ECMO), and low cardiac output syndrome (LCOS-ECMO). Despite established acceptance, ECMO outcomes are suboptimal with a survival between 38% and 55%. We evaluated factors associated with significantly increased survival in cardiac patients requiring ECMO. METHODS We conducted a retrospective investigation of consecutive patients undergoing ECMO between 2006 and 2010. Demographic, pre-ECMO, ECMO, and post-ECMO parameters were analyzed. Neurologic outcomes were assessed with the pediatric overall performance category scale at the latest follow-up. RESULTS There were 3524 admissions, 95 (3%) of which necessitated ECMO; 40 (42%) E-CPR, 31 (33%) OR-ECMO, and 24 (25%) LCOS-ECMO. The overall hospital survival was 73%. The within-groups hospital survival was 75% in E-CPR, 77% OR-ECMO and 62% LCOS-ECMO. In the multivariable logistic regression analysis, chromosomal anomalies (odds ratio [OR], 8; 95% confidence interval [CI], 2-35), single ventricle (OR ,6; 95% CI, 3-33), multiple ECMO runs (OR, 15; 95% CI, 4-42), higher 24-hour ECMO flows (OR, 8; 95% CI, 4-22), decreased lung compliance (OR, 5; 95% CI, 2-16), and need for plasma exchange (OR, 5; 95% CI, 3-18) were all significant factors associated with mortality. From the univariate analysis, a common parameter associated with mortality within all groups was intracranial hemorrhage. At 1.9 years (0.9, 2.9) of follow-up, 66% were still alive, and 89% of survivors had normal function or only mild neurodevelopmental disability. CONCLUSIONS ECMO was successfully used in children with cardiac disease with 73% and 66% short- and intermediate-term survival, respectively. The majority of the survivors had normal function or only a minimal neurodevelopmental deficit.

Extubation after cardiothoracic surgery in neonates, children, and young adults: One year of institutional experience.

Objective: Describe risk factors associated with successful and early extubation in the pediatric cardiac intensive care unit. Design: Retrospective chart review. Setting: University hospital, cardiac intensive care unit. Measurements and Main Results: Review of 212 consecutive surgical admissions from January 2003 to January 2004, excluding deaths. Preoperative, intraoperative, and postoperative variables were studied. Successful extubation was defined as no reintubation at any time during the cardiac intensive care unit course and early extubation was defined as mechanical ventilation ≤24 hrs. Median subject age was 8 months (range, 1 day-25 yrs), with 57% <1 yr of age and 22% neonates. Fifty-eight (27%) were extubated in the operating room and 122 (58%) were extubated at <24 hrs (mean, 6.1 ± 7.7 hrs). Only seven patients failed extubation: three in the operating room because of upper airway obstruction and four in the cardiac intensive care unit for acute respiratory failure associated with atelectasis (n = 2), ventricular dysfunction (n = 1), and arrhythmia (n = 1). There were no extubation failures in patients extubated >24 hrs after surgery. A history of prematurity (odds ratio [OR], 5.84, 2.29–14.9; p < .001), base excess (OR, 1.47, 1.27–1.70; p < .001), cardiopulmonary bypass time (OR, 1.01, 1.01 to −1.2; p < .05), and the need for surgical reintervention (OR, 18.29, 2.78 to −120.07; p < .05) were associated with intubation for >24 hrs. Conclusion: Extubation without the need for reintubation can be achieved in nearly all children following cardiothoracic surgery. The majority of successful extubations can be achieved within 24 hrs of surgery.