Kevin B. Churchwell

Extracorporeal membrane oxygenation in children after repair of congenital cardiac lesions

BACKGROUND The purpose of this study was to review our experience in the early application of extracorporeal membrane oxygenation (ECMO) in patients requiring mechanical assistance after cardiac surgical procedures. METHODS The hospital records of all children requiring ECMO after cardiac operation were retrospectively reviewed, and an analysis of variables affecting survival was performed. RESULTS Fifty pediatric patients between May 1997 and October 2000 required ECMO for cardiopulmonary support after cardiac operation. Patients ranged in age from 1 day to 11 years (median age, 40 days). Forty-eight patients underwent repair of congenital cardiac lesions and 2 were included after receiving a heart transplant. Twenty-two children could not be weaned from cardiopulmonary bypass and were placed on ECMO in the operating room for circulatory support. Of the 28 children who required ECMO in the intensive care unit, 10 had ECMO instituted after cardiopulmonary arrest (mean cardiopulmonary resuscitation time 42 minutes; range, 5 to 110 minutes). In infants with single-ventricle physiology, survival to discharge was 61% (11 of 18 patients) as compared with 43% (14 of 32 patients) in those with biventricular physiology. Thirty of the 50 patients (60%) were successfully weaned from ECMO, of which 25 (83%) were discharged home. Overall survival to discharge in the entire cohort was 50%. Extracorporeal membrane oxygenation support greater than 72 hours was a grave prognostic indicator. Overall survival in this group was 36% (9 of 25 patients) compared with 56% (14 of 25 patients) in those with ECMO support less than 72 hours (p < 0.05). Univariate analysis revealed the presence of renal failure, extended periods of circulatory support, and a prolonged period of cardiopulmonary resuscitation as risk factors for mortality. The presence of shunt-dependent flow, operative procedure, and institution of ECMO in the intensive care unit did not alter survival. CONCLUSIONS Extracorporeal membrane oxygenation provides effective support for postoperative cardiac and pulmonary failure refractory to medical management. Early institution of ECMO may decrease the incidence of cardiac arrest and end-organ damage, thus increasing survival in these critically ill patients.

Clinical outcomes of 84 children with congenital heart disease managed with extracorporeal membrane oxygenation after cardiac surgery.

The purpose of our research was to study the clinical outcomes of children with congenital heart disease (CHD) requiring extracorporeal membrane oxygenation (ECMO) support after cardiac surgery at a tertiary care childrens hospital. Retrospective review of all patients with CHD who required postcardiotomy ECMO between January 2001 and September 2004 (45 months) was undertaken. Various outcome predictors were tested for any association with survival to hospital discharge using univariate analysis. A total of 84 children were placed on ECMO after CHD surgery; 39 (46.4%) were placed on ECMO in the operating room. Median age of the patients was 128 days (1 day to 5 years) and median weight was 4.53 kg (2–18 kg). Active cardiopulmonary resuscitation was ongoing at the time of cannulation in 27 children (32%). Fifty-two children (61.9) survived > 24 hours after decannulation and 31 (36.9%) survived to discharge. High arterial serum lactate levels at the time of ECMO initiation were strongly correlated with nonsurvival (p = 0.004). Nonsurvivors had longer duration on ECMO than survivors (p = 0.003). The odds of survival dropped significantly after 144 hours (day 6) of ECMO. ECMO support results in improved outcomes in patients who suffered hemodynamic collapse post cardiac surgery. Underlying cardiac lesion, age, weight, gender, initial arterial pH, location of ECMO initiation, need for hemofiltration and placement of ECMO after active ongoing cardiopulmonary resuscitation did not increase the mortality risk. Initial arterial serum lactate level and inability to wean off by 6 days were strongly correlated with nonsurvival.

Coagulopathy as a predictor of outcome in meningococcal sepsis and the systemic inflammatory response syndrome with purpura

ObjectiveTo identify simple, contemporary predictors of both morbidity and mortality in pediatric patients with purpuric sepsis syndrome in order to provide a basis for future study of innovative interventions. DesignRetrospective study. SettingAn 18-bed multidisciplinary intensive care unit (ICU) in a large pediatric hospital. PatientsA total of 53 patients, ranging in age from 18 days to 17 yrs (mean 4.9 yrs) with either culture-proven meningococcal sepsis or the systemic inflammatory response syndrome with purpura, who were admitted to the ICU during the period from January 1, 1982 through March 15, 1992. MethodsA computerized database was constructed containing the characteristics of these patients at presentation, during the first 24 hrs of hospitalization, and on discharge. Single variables were screened for significance between “good” (intact survival) and “poor” (mortality or survival with significant morbidity) outcome groups. Those variables found to be most significant were then tested for sensitivity, specificity, and predictive value. The best predictors identified in this manner were then compared with the two most-cited prognosticating strategies as applied to these patients. Measurements and Main ResultsCoagulopathy (defined as a partial thromboplastin time >50 secs or serum fibrinogen concentration <150 mg/ dL [4.4 μmol/L]) at the referral site or on ICU admission was identified as an excellent predictor of poor outcome: sensitivity, specificity, positive and negative predictive values of a low serum fibrinogen value, being 81%, 95%, 93%, and 88%, and of prolonged partial thromboplastin time, being 95%, 90%, 86%, and 97%, respectively. Classical prognosticating strategies were found to be inadequately associated with mortality, yet comparable with coagulopathy in identifying patients destined for clinically important morbidity. ConclusionsWe conclude that: a) outcome of pediatric patients with meningococcal sepsis or the systemic inflammatory response syndrome with purpura can be predicted rapidly, more easily, and with overall accuracy superior to classical prognostication strategies by the simple presence or absence of coagulopathy; b) when applied to a contemporary population, classical prognostication strategies lack value for prediction of mortality, yet remain valid for prediction of “poor outcome” (significant morbidity + mortality); c) when evaluating treatment strategies for such patients, the presence of serious coagulopathy may potentially be useful as an index of illness severity. (Crit Care Med 1993; 21:706–711)

Leukopheresis therapy for severe infantile pertussis with myocardial and pulmonary failure.

Objective: To describe an infant with severe pertussis successfully treated with leukopheresis. Design: Case report. Setting: Pediatric intensive care unit of a children’s hospital. Patient: Five-wk-old female with pertussis complicated by cardiorespiratory failure. Interventions: Single leukopheresis treatment. Measurements and Main Results: Normalization of the white blood cell count and marked cardiorespiratory improvement after treatment; patient survived. Conclusion: Given the temporal association between treatment and improvement, we hypothesize that the markedly elevated white blood cell count has a major role in the cardiopulmonary compromise.

Methemoglobinemia: Toxicity of inhaled nitric oxide therapy.

Elevation in methemoglobin is a known toxicity of inhaled nitric oxide (NO) therapy. This article describes two significant episodes of methemoglobinemia. These cases illustrate the probable cause and the treatment strategies for the potential for delivery of high concentrations of NO, resulting in methemoglobinemia with moderate and even low-dose delivered NO. We propose mechanisms for this occurrence and means of prevention.

Patient Safety as an Academic Discipline

S ignificant improvement in the delivery of safe and effective care of children will not occur until fundamental gaps in the organization of care are understood and resolved. Most errors and failures in healthcare are the product of poorly designed, poorly engineered, and poorly coordinated care that does not recognize the complexity and tight coupling of contemporary healthcare across many sites and services and in the home. Although there has been success in developing specific interventions to prevent error and improve outcomes (eg, central line and ventilator-associated pneumonia bundles, bar-coding, provider order entry, crew resource management), most error results from fragmented and unnecessarily complex processes, poor communication, lack of team work, and failure to understand technical work in a detailed and coherent manner. Uncertainty and confusion are common and contribute to the inability of patients, families, and providers to find their way through the labyrinth that is today’s healthcare: incomplete information, un-reconciled medications, and production pressures. These examples are but a few of the many barriers to safe and reliable care that require study. Doctors, nurses, and other professionals struggle to improve the conditions in which they work, but they often lack the knowledge and skills to make a significant difference. The need exists to comprehensively address the problems and challenges of today’s healthcare in a practical and highly disciplined way. This need can be met, for example, with the creation of ‘‘test-beds’’ to engineer and study quality and safety improvements for children and families. There is, however, argument about what constitutes legitimate methods to study and build evidence for reliable patient safety practices and care models. The release of the Institute of Medicine’s report, ‘‘To Err is Human: Building a Safer Health System,’’ mobilized attention, but the work of safer health care has proven more difficult, time consuming, and expensive than expected. Cook articulates that most efforts have been in applications rather than explorations into patient safety itself, and that applications alone cannot provide insights into basic mechanisms of why an intervention works or fails, so there is limited new knowledge to substantially improve patient safety.We believe it is time to get on with the work at hand and correct the perception that the large, randomized clinical trial is the only valid research. Although there is comparatively little published in medical journals about patient safety im-

Peak pressures or plateau pressures in asthma

Sir: We thank Drs. Agarwal and Nath for their interest in our recent publication [1]. We agree that the difference between peak inspiratory pressure (PIP) and plateau pressure (Pplat) is widened in patients with reactive airway disease such as asthma. We also concur with their observation that Pplat better reflects the degree of alveolar hyperinflation. However, we disagree with their statement that PIP has no clinical relevance in children with severe asthma. On the contrary, it is PIP (or the difference between PIP and Pplat) that is elevated in asthma and is correlated with the degree of bronchospasm and increased airway resistance. We feel that PIP is a better surrogate than Pplat of the degree of airway obstruction (due to airway inflammation and bronchospasm, the underlying pathophysiology of acute asthma) and better reflects both disease severity and the response to bronchodilators and anti-inflammatory agents. Isoflurane was used in our patients to reduce the severely increased airway resistance, and we feel that PIP reflects this resistive component better than Pplat. We would also like to clarify few other issues raised by them: All our patients were on volume-controlled mode of ventilation (pressure regulated volume control mode), and PIP was not the primary determinant of setting the tidal volume. The tidal volumes were selected based on the physiological range of 5–8 ml/kg. We did not use fast inspiratory flow rates with square waveform, as implied by them; rather, the mode we used in our patient delivered a decelerating flow waveform. We would also like to point out that for various practical reasons obtaining repeated accurate Pplat measurements was not feasible; most of the children were being administered continuous albuterol nebulization in the inspiratory limb of the circuit, and the constant gas flow associated with this therapy interfered with the measurement of Pplat. Additionally, it has been our experience that in children there is sufficient leak around even partially inflated cuffed endotracheal tubes that precludes achieving a steady value of Pplat during an inspiratory hold maneuver. Although higher PIP may not have been associated with increased incidence of air leaks in many studies, even Pplat has not been shown to have a correlation with pulmonary barotrauma in a recent large study [2]. We agree with Drs Agarwal and Nath that degree of dynamic hyperinflation (DHI) is better reflected by Pplat rather than by PIP, but DHI was not our primary indication for administration of isoflurane. Evidence of increasing respiratory acidosis and poor alveolar minute ventilation despite adequate delivered tidal volume was often the indication. We believe that this resulted from increasing airway resistance, better reflected by PIP than Pplat and therefore was a better choice for purposes of our observations. References