George M. Hoffman

Home surveillance program prevents interstage mortality after the Norwood procedure

OBJECTIVE To determine whether early identification of physiologic variances associated with interstage death would reduce mortality, we developed a home surveillance program. METHODS Patients discharged before initiation of home surveillance (group A, n = 63) were compared with patients discharged with an infant scale and pulse oximeter (group B, n = 24). Parents maintained a daily log of weight and arterial oxygen saturation according to pulse oximetry and were instructed to contact their physician in case of an arterial oxygen saturation less than 70% according to pulse oximetry, an acute weight loss of more than 30 g in 24 hours, or failure to gain at least 20 g during a 3-day period. RESULTS Interstage mortality among infants surviving to discharge was 15.8% (n = 9/57) in group A and 0% (n = 0/24) in group B (P =.039). Surveillance criteria were breached for 13 of 24 group B patients: 12 patients with decreased arterial oxygen saturation according to pulse oximetry with or without poor weight gain and 1 patient with poor weight gain alone. These 13 patients underwent bidirectional superior cavopulmonary connection (stage 2 palliation) at an earlier age, 3.7 +/- 1.1 months of age versus 5.2 +/- 2.0 months for patients with an uncomplicated interstage course (P =.028). A growth curve was generated and showed reduced growth velocity between 4 and 5 months of age, with a plateau in growth beyond 5 months of age. CONCLUSION Daily home surveillance of arterial oxygen saturation according to pulse oximetry and weight selected patients at increased risk of interstage death, permitting timely intervention, primarily with early stage 2 palliation, and was associated with improved interstage survival. Diminished growth identified 4 to 5 months after the Norwood procedure brings into question the value of delaying stage 2 palliation beyond 5 months of age.

Unmeasured anions identified by the Fencl-stewart method predict mortality better than base excess, anion gap, and lactate in patients in the pediatric intensive care unit

OBJECTIVES This study was undertaken to compare three methods for the identification of unmeasured anions in pediatric patients with critical illness. We compared the base excess (BE) and anion gap (AG) methods with the less commonly used Fencl-Stewart strong ion method of calculating BE caused by unmeasured anions (BEua). We measured the relationship of unmeasured anions identified by the three methods to serum lactate concentrations and to mortality. DESIGN Retrospective cohort study. SETTING Tertiary care pediatric intensive care unit in an academic pediatric hospital. PATIENTS The study population included 255 patients in the pediatric intensive care unit who had simultaneous measurements of arterial blood gases, electrolytes, and albumin during the period of July 1995 to December 1996. Sixty-six of the 255 patients had a simultaneous measurement of serum lactate. MEASUREMENTS AND MAIN RESULTS The BEua was calculated using the Fencl-Stewart method. The AG was defined as (sodium plus potassium) - (chloride plus total carbon dioxide). BE was calculated from the standard bicarbonate, which is derived from the Henderson-Hasselbalch equation and reported on the blood gas analysis. A BE or BEua value of < or =-5 mEq/L or an AG > or =17 mEq/L was defined as a clinically significant presence of unmeasured anions. A lactate level of > or =45 mg/dL was defined as being abnormally elevated for this study. The presence of unmeasured anions identified by significantly abnormal BEua was poorly identified by BE or AG. Of the 255 patients included in the study, 67 (26%) had a different interpretation of acid base balance when the Fencl method was used compared with when BE and AG were used. Plasma lactate concentration correlated better with BEua (r2 = .55; p = .0001) than with AG (r2 = .41; p = .0005) or BE (r2 = .27; p = .025). Mortality was more strongly related to BEua < or =-5 mEq/L (relative risk of death = 10.25; p = .002) than to lactate > or =45 mg/dL (relative risk of death = 2.35; p = .04). In logistic regression analysis, mortality was more strongly associated with BEua (area under the receiver operating characteristic curve = 0.79; p = .0002) than lactate (receiver operating characteristic curve area = 0.63; p = .05), BE (receiver operating characteristic curve area = 0.53; p = .32), or AG (receiver operating characteristic curve area = 0.64; p = .08) in this patient sample. CONCLUSIONS Critically ill patients with normal BE and normal AG frequently have elevated unmeasured anions detectable by BEua. The Fencl-Stewart method is better than BE and similar to AG in identifying patients with high lactate levels. Elevated unmeasured anions identified by the Fencl-Stewart method were more strongly associated with mortality than with BE, AG, or lactate in this patient sample.

Phenoxybenzamine improves systemic oxygen delivery after the Norwood procedure

BACKGROUND Achieving adequate systemic oxygen delivery after the Norwood procedure frequently is complicated by excessive pulmonary blood flow at the expense of systemic blood. We hypothesized that phenoxybenzamine could achieve a balanced circulation through reduction of systemic vascular resistance. METHODS In this prospective, nonrandomized study, oximetric catheters were placed in the superior vena cava for continuous monitoring of systemic venous oxygen saturation. Postoperative hemodynamic variables were compared between 7 control patients and 8 patients who received phenoxybenzamine. RESULTS The hospital survival rate was 93% (14 of 15 patients). Improvements in postoperative hemodynamics in the phenoxybenzamine group included a higher systemic venous oxygen saturation, a narrower arteriovenous oxygen content difference, a lower ratio of pulmonary to systemic flow, and a lower indexed systemic vascular resistance. In the phenoxybenzamine group, mean arterial blood pressure was related directly to systemic oxygen delivery, in contrast to the control group, where mean arterial pressure was related directly to indexed systemic vascular resistance and the ratio of pulmonary to systemic circulation. CONCLUSIONS Continuous postoperative monitoring of systemic venous oxygen saturation in a patient who has undergone the Norwood procedure provides early identification of low systemic oxygen delivery and an elevated ratio of pulmonary to systemic circulation. In this pilot study, phenoxybenzamine appeared to improve systemic oxygen delivery during the early postoperative period after the Norwood procedure. Further studies are indicated to confirm these results.

Venous saturation and the anaerobic threshold in neonates after the Norwood procedure for hypoplastic left heart syndrome

BACKGROUND Reduction in oxygen delivery can lead to organ dysfunction and death by cellular hypoxia, detectable by progressive (mixed) venous oxyhemoglobin desaturation until extraction is limited at the anaerobic threshold. We sought to determine the critical level of venous oxygen saturation to maintain aerobic metabolism in neonates after the Norwood procedure (NP) for the hypoplastic left heart syndrome (HLHS). METHODS A prospective perioperative database was maintained for demographic, hemodynamic, and laboratory data. Invasive arterial and atrial pressures, arterial saturation, oximetric superior vena cava (SVC) saturation, and end-tidal CO2 were continuously recorded and logged hourly for the first 48 postoperative hours. Arterial and venous blood gases and cooximetry were obtained at clinically appropriate intervals. SVC saturation was used as an approximation of mixed venous saturation (SvO2). A standard base excess (BE) less than -4 mEq/L (BElo), or a change exceeding -2 mEq/L/h (deltaBElo), were used as indicators of anaerobic metabolism. The relationship between SvO2 and BE was tested by analysis of variance and covariance for repeated measures; the binomial risk of BElo or deltaBElo at SvO2 strata was tested by the likelihood ratio test and logistic regression, with cutoff at p < 0.05. RESULTS Complete data were available in 48 of 51 consecutive patients undergoing NP yielding 2,074 valid separate determinations. BE was strongly related to SvO2 (model R2 = 0.40, p < 0.0001) with minimal change after adjustment for physiologic covariates. The risk of anaerobic metabolism was 4.8% overall, but rose to 29% when SvO2 was 30% or below (p < 0.0001). Survival was 100% at 1 week and 94% at hospital discharge. CONCLUSIONS Analysis of acid-base changes revealed an apparent anaerobic threshold when SvO2 fell below 30%. Clinical management to maintain SvO2 above this threshold yielded low mortality.

Fontan Palliation in the Modern Era: Factors Impacting Mortality and Morbidity

BACKGROUND Advances in management of the Fontan patient include interval superior cavopulmonary shunt, total cavopulmonary connection, either lateral tunnel or extracardiac conduit, and the use of a fenestration. Coincident with these improvements, Fontan palliation has been applied to a wider ranger of anatomic subgroups. METHODS A cross-sectional analysis of 256 consecutive patients undergoing a total cavopulmonary connection Fontan after superior cavopulmonary shunt between January 1, 1994, and June 30, 2007 were studied. Fenestration was used selectively. Fontan failure was defined as death, transplant, or takedown. Event-free survival was defined as freedom from death, transplant, Fontan takedown, functional class III to IV, pacemaker, antiarrhythmic medication, protein-losing enteropathy, stroke, or thrombus. RESULTS Survival was 97% +/- 1%, 96% +/- 1%, and 94% +/- 2%, respectively, at 1, 5, and 10 years. Event-free survival was 96% +/- 1%, 87% +/- 3%, and 64% +/- 6%, respectively, at 1, 5, and 10 years. Factors predicting worse event-free survival included longer cross-clamp time (p = 0.003), fenestration (p = 0.014), and longer hospital length of stay (p = 0.016). Ventricular morphology did not predict outcome. Left ventricle (n = 113, 44%) versus right ventricle (n = 142, 56%) failure-free survival (death, transplant, or Fontan takedown) at 10 years was 92% +/- 4% versus 91% +/- 3%, respectively (p = 0.19). Left ventricle versus right ventricle event-free survival at 10 years was 75% +/- 7% versus 67% +/- 9%, respectively (p > 0.1). CONCLUSIONS Survival for patients undergoing a completion Fontan in the current era is excellent, but patients remain at risk for morbid events. In the intermediate follow-up period, we could not identify a difference in outcome between dominant left and right ventricle morphology.

Electroacupuncture Prophylaxis of Postoperative Nausea and Vomiting following Pediatric Tonsillectomy with or without Adenoidectomy

Background Electrical stimulation of acupuncture point P6 reduces the incidence of postoperative nausea or vomiting (PONV) in adult patients. However, acupressure, laser stimulation of P6, and acupuncture during anesthesia have not been effective for reducing PONV in the pediatric population. The authors studied the effect of electrical P6 acupuncture in awake pediatric patients who had undergone surgery associated with a high incidence of PONV. Methods Patients aged 4–18 yr undergoing tonsillectomy with or without adenoidectomy were randomly assigned to acupuncture, sham acupuncture, or control groups. Acupuncture needles at P6 and a neutral point were placed while patients were anesthetized, and low-frequency electrical stimulation was applied to these points for 20 min in the recovery room while the patients were awake (P6 Acu group). This treatment was compared with sham needles along the arm at acupuncture points not associated with antiemesis (sham group) and a no-needle control group. The arms were wrapped to prevent identification of treatment group, and anesthetic, analgesic, and surgical technique were standardized. Assessed outcomes were occurrence of nausea, occurrence and number of episodes of vomiting, time to vomiting, and use of antiemetic rescue medication. Results One hundred twenty patients were enrolled in the study, 40 per group. There were no differences in age, weight, sex, or opioid administration between groups. The PONV incidence was significantly lower with P6 acupuncture (25 of 40 or 63%; odds ratio, 0.135; number needed to treat, 3.3;P < 0.001) compared with controls (37 of 40 or 93%). Sham puncture had no effect on PONV (35 of 40 or 88%;P = not significant). Occurrence of nausea was significantly less in P6 Acu (24 of 40 or 60%; odds ratio, 0.121;P < 0.01), but not in the sham group (34 of 40 or 85%) compared with the control group (37 of 40 or 93%). Vomiting occurred in 25 of 40 or 63% in P6 Acu; 35 of 40 or 88% in the sham group, and 31 in 40 or 78% in the control group (P = not significant). Patients receiving sham puncture vomited significantly earlier (P < 0.02) and needed more rescue treatment (33 of 40 or 83%; odds ratio, 3.48;P < 0.02) compared with P6 Acu (23 of 40 or 58%) and the control group (24 of 40 or 60%). Conclusions Perioperative P6 electroacupuncture in awake patients significantly reduced the occurrence of nausea compared with the sham and control groups, but it did not significantly reduce the incidence or number of episodes of emesis or the use of rescue antiemetics. Sham acupuncture may exacerbate the severity but not the incidence of emesis. The efficacy of P6 acupuncture for PONV prevention is similar to commonly used pharmacotherapies. Its appropriate role in prevention and treatment of PONV requires further study.

Alteration of the critical arteriovenous oxygen saturation relationship by sustained afterload reduction after the Norwood procedure

OBJECTIVES Hemodynamic vulnerability after the Norwood procedure for hypoplastic left heart syndrome results from impaired myocardial function, and critical inefficiency of parallel circulation. Traditional management strategies have attempted to optimize circulatory efficiency by using arterial oxygen saturation (SaO(2)) as an index of pulmonary/systemic flow balance, attempting to maintain SaO(2) within a theoretically optimal critical range of 75% to 80%. This optimal range of SaO(2) has not been verified clinically, and strategies targeting SaO(2) may be limited by the fact that SaO(2) is a poor predictor of systemic oxygen delivery. We have previously reported higher venous saturation (SvO(2)), lower arteriovenous oxygen content difference, lower systemic vascular resistance, lower pulmonary/systemic flow ratio, and improved survival with the perioperative use of phenoxybenzamine and continuous monitoring of SvO(2). In this investigation, we tested the hypothesis that intense afterload reduction with phenoxybenzamine would modify the SvO(2)-SaO(2) relationship by preventing deterioration of systemic oxygen delivery at high SaO(2). METHODS Seventy-one consecutive neonates undergoing the Norwood procedure with and without phenoxybenzamine were studied. Perioperative hemodynamic management targeted SvO(2) greater than 50%. Hemodynamic data were prospectively acquired for 48 hours postoperatively and analyzed to assess the effect of phenoxybenzamine on the relationship between SaO(2) and SvO(2) and other hemodynamic indices. Sixty-two patients received phenoxybenzamine 0.25 mg/kg on cardiopulmonary bypass; 9 who did not served as controls. RESULTS In control patients, SvO(2) peaked at an SaO(2) of 77%, with reduced SvO(2) at SaO(2) > 85% and SaO(2) < 70% (P <.01), while arteriovenous oxygen content difference increased with SaO(2) greater than 80% (P <.001). In patients receiving phenoxybenzamine, the SvO(2) increased linearly with SaO(2) greater than 65% (P <.001), and arteriovenous oxygen content difference was constant at all SaO(2) (P = ns). The SvO(2) was higher, and the arteriovenous oxygen content difference lower, across the whole SaO(2) range with phenoxybenzamine (P <.0001). CONCLUSIONS A critical range of SaO(2) for optimizing systemic oxygen delivery was confirmed in control patients, and was effectively eliminated by phenoxybenzamine, specifically by eliminating the systemic hypoperfusion associated with high SaO(2). This effect allows higher SaO(2) to be included in a rational hemodynamic strategy to improve systemic oxygen delivery in the early postoperative management of patients receiving intense afterload reduction with phenoxybenzamine. The predictability of SvO(2) from SaO(2) is low in both groups, emphasizing the importance of SvO(2) measurement in these patients.

Patients at risk for low systemic oxygen delivery after the Norwood procedure

BACKGROUND Identification of patients at risk for inadequate systemic oxygen delivery following the Norwood procedure could allow for application of more intensive monitoring, provide for earlier intervention of decreased cardiac output, and result in improved outcome. METHODS AND RESULTS Superior vena cava saturation (SvO2) and arteriovenous oxygen content difference were prospectively monitored as indicators of systemic oxygen delivery and recorded hourly for the first 48 hours in 29 of 33 consecutive patients following the Norwood procedure. Risk factors were evaluated using multiple linear regression to determine their impact on SvO2 and arteriovenous oxygen content difference. Age less than 8 days, weight less than 2.5 kg, aortic atresia, and prolonged cardiopulmonary bypass time were risk factors for low SvO2 and wide arteriovenous oxygen content difference (p < 0.05). Phenoxybenzamine and increasing time after operation were associated with higher SvO2 and narrower arteriovenous oxygen content difference (p < 0.05). Thirty-day survival was 97% and hospital survival was 94%. The earliest death occurred on postoperative day 20. Survival to bidirectional cavopulmonary shunt was 77%. Preoperative mechanical ventilation was the only risk factor identified for late death. CONCLUSIONS Aortic atresia, low weight, younger age, and prolonged cardiopulmonary bypass, previously identified risk factors for mortality, were associated with decreased SvO2 and narrower arteriovenous oxygen content difference in the early postoperative period. The impact of this hemodynamic vulnerability on mortality was minimized by continuous SvO2 monitoring.

Risk and Prevalence of Developmental Delay in Young Children With Congenital Heart Disease

BACKGROUND AND OBJECTIVE: Children with congenital heart disease (CHD) are at risk for developmental delay (DD). Changes in cognitive, language, and motor skills in early childhood have not been described. We report the results of a structured approach using longitudinal testing to identify problems and ensure early intervention in accordance with published guidelines. METHODS: Bayley Scales of Infant Development, Third Edition, were used to assess cognitive, language, and motor skills in 99 children with CHD. Subjects were evaluated 3 to 6 times in the first 3 years of life. DD was defined as scores >1 SD below the population mean. RESULTS: Cardiac anatomy was single ventricle (1V) in 34 subjects and 2 ventricles (2V) in 65. Medical comorbidities were present in 21% and genetic syndromes in 19%. Most subjects (75%) had DD in ≥1 area at ≥1 assessments. Subjects with 1V anatomy had equivalent outcomes to those with 2V. Cognitive and language scores declined in subjects with genetic syndromes but were stable and within the average range for subjects with 1V and 2V. Motor scores improved for subjects with 1V and 2V but remained low for those with genetic syndromes. In addition to age, need for supplemental tube feeding, longer cardiopulmonary bypass time, and shorter time since last hospitalization were significant predictors of developmental outcomes. CONCLUSIONS: DDs in young children with CHD are both common and dynamic. Providers should encourage longitudinal surveillance for children with CHD because exposure to risk and prevalence of DD change over time.

Epidural analgesia improves outcome following pediatric fundoplication: A retrospective analysis

Background and Objectives. Nissen fundoplication is a common procedure in high‐risk pediatric patients. This cohort study evaluated the influence of epidural versus intravenous opioid analgesia on the postoperative course of infants and children undergoing fundoplication. Methods. A retrospective review was made of the perioperative courses of 155 consecutive patients, aged 1 month to 19 years, who underwent elective open fundoplication from January 1993 to October 1994. Of these 155 patients, 72 received perioperative analgesia with epidural opioids, while 83 received parenteral opioids. Outcome variables included major morbidity factors, recovery of bowel and bladder function, and economic impact. Results. Patients in the epidural and parenteral groups did not differ with respect to age, weight, or associated preoperative medical diagnoses. The postoperative complication rate was significantly decreased in the epidural group (5.5% versus 20%) (P < .001). In the epidural group 4 patients required mechanical ventilation for longer than 24 hours, compared with 15 in the parenteral group. Patients in the epidural group were discharged earlier from the hospital and incurred approximately 20% less in hospital charges on average than their cohorts in the intravenous group. Conclusions. These findings suggest that perioperative epidural analgesia, administered by a dedicated pain service, amy improve outcome in high‐risk pediatric patients undergoing fundoplication.