Keith C. Kocis

High-frequency oscillatory ventilation in pediatric respiratory failure: A multicenter experience

ObjectiveThe use of high-frequency oscillatory ventilation (HFOV) has increased dramatically in the management of respiratory failure in pediatric patients. We surveyed ten pediatric centers that frequently use high-frequency oscillation to describe current clinical practice and to examine factors related to improved outcomes. DesignRetrospective, observational questionnaire study. SettingTen tertiary care pediatric intensive care units. PatientsTwo hundred ninety patients managed with HFOV between January 1997 and June 1998. InterventionsNone. Measurements and Main ResultsPatients were classified according to presence or absence of preexisting lung disease, symptomatic respiratory syncytial virus infection, or presence of cyanotic heart disease or residual right-to-left intracardiac shunt. In addition, patients for whom HFOV acutely failed were analyzed separately. Those patients with preexisting lung disease were significantly smaller, had a significantly higher incidence of pulmonary infection as the triggering etiology, and had a significantly greater duration of conventional ventilation before institution of HFOV compared with patients without preexisting lung disease. Stepwise logistic regression was used to predict mortality and the occurrence of chronic lung disease in survivors. In patients without preexisting lung disease, the model predicted a 70% probability of death when the oxygenation index (OI) after 24 hrs was 28 in the immunocompromised patients and 64 in the patients without immunocompromise. In the immunocompromised patients, the model predicted a 90% probability of death when the OI after 24 hrs was 58. In survivors without preexisting lung disease, the model predicted a 70% probability of developing chronic lung disease when the OI at 24 hrs was 31 in the patients with sepsis syndrome and 50 in the patients without sepsis syndrome. In the patients with sepsis syndrome, the model predicted a 90% probability of developing chronic lung disease when the OI at 24 hrs was 45. ConclusionsGiven the number of centers involved and the size of the database, we feel that our results broadly reflect current practice in the use of HFOV in pediatric patients. These results may help in deciding which patients are most likely to benefit from aggressive intervention by using extracorporeal techniques and may help identify high-risk populations appropriate for prospective study of innovative modes of supporting gas exchange (e.g., partial liquid breathing or intratracheal pulmonary ventilation).

Late follow-up of balloon angioplasty in children with a native coarctation of the aorta

Between May 1984 and April 1993, 59 children underwent balloon angioplasty of a native coarctation at our institution. The follow-up protocol included a cardiac catheterization 1 to 2 years after angioplasty, which was performed in 90% of patients with > or = 2 years follow-up. Angioplasty caused an acute decrease in peak systolic gradient from 46 +/- 2 to 15 +/- 2 mm Hg, without early aneurysm or emergent surgical intervention in any patient. Based on follow-up data, a satisfactory result was obtained in 38 patients (64%; 70% confidence limit: 58% to 71%), defined as a residual systolic gradient < 20 mm Hg and no aneurysm. In these patients the gradient decreased acutely from 43 +/- 2 to 9 +/- 1 mm Hg, was 6 +/- 1 mm Hg at follow-up catheterization, and 9 +/- 2 mm Hg by clinical evaluation 4.4 +/- 0.3 years after angioplasty. Twenty-one patients (36%; 70% confidence limit: 29% to 42%) had an unsatisfactory result due to a residual gradient > or = 20 mm Hg (n = 19) or aneurysm formation (n = 3), or both. Restenosis occurred in 6 patients, and occurred more in infants than in children > or = 12 months of age (3 of 5 infants vs 3 of 41 children, p = 0.01). Thus, balloon angioplasty provides an effective initial treatment strategy for native coarctation in most children aged > 12 months.

Probiotic administration and the incidence of nosocomial infection in pediatric intensive care: a randomized placebo-controlled trial.

Objective: To evaluate the efficacy of probiotics in reducing the rates of nosocomial infection in pediatric intensive care. Design: Randomized, double-blind, placebo-controlled trial. Setting: A 16-bed pediatric intensive care unit in a university-affiliated children’s hospital. Patients: Sixty-one pediatric patients were enrolled from April 2004 until December 2004. Screening of all patients admitted occurred on a daily basis. Patients were excluded if they had the following: evidence/suspicion of intestinal perforation, evidence/suspicion of mechanical gastrointestinal obstruction, absolute neutrophil count ≤0.5 × 109 cells/L, judgment by the attending physician that unable to tolerate the enteral volume necessary for administration, use of a probiotic preparation at any time in the week before study entry, participation in another clinical trial, lack of parental presence, or lack of parental consent. Interventions: Patients were randomized to receive either one capsule of Lactobacillus rhamnosus strain GG (Culturelle, ConAgra Foods, Omaha, NE) or placebo capsule of insulin once a day until discharge from the hospital. Results: Sixty-one patients were randomized: 31 in the treatment group and 30 on the placebo group. Three patients in the control group developed four infections. Six patients in the treatment group developed 11 infections. The relative risk of developing infection in the treatment group was 1.94 (confidence interval [CI], 0.53 to 7.04; p = .31). The mean number of infections in the treatment and control groups was 1.83 and 1.33, respectively, with a difference of 0.5 (p = .52). No serious adverse effects in the study population were noted. However, due to recent safety concerns regarding the administration of L. rhamnosus strain GG and a lack of benefit in this interim analysis, the study was terminated by the study investigators. Conclusions: The results of this preliminary investigation were unexpected but important in view of the increased use of probiotic preparations in medically fragile pediatric patients. In this randomized, placebo-controlled trial, L. rhamnosus strain GG was not shown to be effective in reducing the incidence of nosocomial infections. In fact, a statistically nonsignificant trend toward an increase in infection was seen (four vs. 11). Further studies with a larger patient population are needed to establish both safety and efficacy of probiotics in pediatric critical care.

ACCF/AHA/AAP recommendations for training in pediatric cardiology

SUMMARY It is vital to the future intellectual health of cardiovascularmedicine and the welfare of pediatric patients with cardiovas-cular disease that all future pediatric cardiologists be familiarwith the principles and tools of research. Training in researchrequires the intense involvement of productive and establishedinvestigators. Those trainees preparing for a career in investi-gative cardiology require a carefully developed but flexibleeducational plan that will permit them to be successful in theirresearch careers over an extended period. REFERENCES 1. Sonnenblick EH, Ryan TI, Starke RD. Task force 7: training incardiovascular research. J Am Coll Cardiol 1995;25:25–8.2. Roberts R, Alexander RW, Loscalzo J, Williams RS. Task force 7:training in cardiovascular research. Available at: http://www.acc.org/clinical/training/cocats2.pdf 2002. Accessed August 10, 2004.3. NHLBI Task Force Report on Pediatric Cardiovascular Diseases.Available at: http://www.nhlbi.nih.gov/resources/docs/pediatric_cvd.pdf.Accessed August 10, 2004.

Safety and Feasibility of High-pressure Transvenous Limb Perfusion With 0.9% Saline in Human Muscular Dystrophy

We evaluated safety and feasibility of the transvenous limb perfusion gene delivery method in muscular dystrophy. A dose escalation study of single limb perfusion with 0.9% saline starting with 5% of limb volume was carried out in adults with muscular dystrophies under intravenous analgesia/anesthesia. Cardiac, vascular, renal, muscle, and nerve functions were monitored. A tourniquet was placed above the knee with inflated pressure of 310 mm Hg. Infusion was carried out with a clinically approved infuser via an intravenous catheter inserted in the saphenous vein with a goal infusion rate of 80 ml/minute. Infusion volume was escalated stepwise to 20% limb volume in seven subjects. No subject complained of any post procedure pain other than due to needle punctures. Safety warning boundaries were exceeded only for transient depression of limb tissue oximetry and transient elevation of muscle compartment pressures; these were not associated with nerve, muscle, or vascular damage. Muscle magnetic resonant imaging (MRI) demonstrated fluid accumulation in muscles of the perfused lower extremity. High-pressure retrograde transvenous limb perfusion with saline up to 20% of limb volume at above infusion parameters is safe and feasible in adult human muscular dystrophy. This study will serve as a basis for future gene transfer clinical trials.

Pulse contour cardiac output analysis in a piglet model of severe hemorrhagic shock

Objective:Pulse contour cardiac output (PCCO) analysis is a technique for continuous cardiac output (CO) monitoring through an arterial catheter after calibration by transpulmonary thermodilution (TPTD). Studies in adults show good correlation with pulmonary artery thermodilution (PATD) CO. Data are limited in children and patients with hemodynamic instability. The objective was to determine whether TPTD CO and PCCO analysis correlate with PATD CO in a piglet model of severe hemorrhagic shock. Mixed venous oxygen saturation (S&OV0413;o2) was also compared with PATD CO. Design:Prospective animal study. Setting:University animal research laboratory. Subjects:Domesticated piglets, 24–37 kg. Interventions:Hemorrhagic shock was created by graded hemorrhage in anesthetized piglets. Hemorrhage was initiated to achieve mean arterial pressure plateaus of 60, 50, 40, 30, and 20 mm Hg. Measurements and Main Results:CO was measured by PATD and simultaneously with two femoral artery PCCO catheters. At each mean arterial pressure plateau, one PCCO catheter was recalibrated by TPTD; the other catheter was not recalibrated during hemorrhage. TPTD CO, PCCO measurements from each catheter, and S&OV0413;o2 were compared with PATD CO at each mean arterial pressure level. TPTD CO and recalibrated PCCO showed excellent correlation (r2 = .96 and .97) and small bias (+0.11 and +0.14 L/min), respectively, compared with PATD. Without recalibration, PCCO measurements were not accurate during rapid hemorrhage (r2 = .22). S&OV0413;o2 decline did not correlate as well with PATD CO (r2 = .69). Conclusions:TPTD CO and recalibrated PCCO analysis correlate well with PATD CO in this severe hemorrhagic shock model. The mean difference is small (<0.15 L/min) and is not clinically significant. With rapid changes in blood pressure or intravascular volume, PCCO is not accurate unless recalibrated by TPTD CO. S&OV0413;o2 did not correlate well with CO in this model.

Pressure-regulated volume control vs volume control ventilation in infants after surgery for congenital heart disease.

Abstract. The objective of this investigation was to compare how two modes of positive pressure ventilation affect cardiac output, airway pressures, oxygenation, and carbon dioxide removal in children with congenital heart disease in the immediate postoperative period. The investigation used a one group pretest–post-test study design and was performed in the pediatric cardiac intensive care unit in a university-affiliated childrens hospital. Nine infants were enrolled immediately after repair of tetralogy of Fallot (2) or atrioventricular septal defects (7) with mean weight = 5.5 kg (4.2–7.3 kg). Children were admitted to the pediatric cardiothoracic intensive care unit after complete surgical repair of their cardiac defect and stabilized on a Siemens Servo 300 ventilator in volume control mode (VCV1) (volume-targeted ventilation with a square flow wave pattern). Tidal volume was set at 15 cc/kg (total). Hemodynamic parameters, airway pressures and ventilator settings, and an arterial blood gas were measured. Patients were then changed to pressure-regulated volume control mode (PRVC) (volume-targeted ventilation with decelerating flow wave pattern) with the tidal volume set as before. Measurements were repeated after 30 minutes. Patients were then returned to volume control mode (VCV2) and final measurements made after 30 minutes. The measurements and results are as follows:After correction of congenital heart defects in infants, mechanical ventilation using a decelerating flow wave pattern resulted in a 19% decrease in peak inspiratory pressure without affecting hemodynamics, arterial oxygenation, or carbon dioxide removal.

Two-dimensional and Doppler ultrasound evaluation of femoral arteries in infants after cardiac catheterization.

In conclusion, femoral artery obstruction occurs frequently (32%) in infants <1 year old undergoing cardiac catheterization. Two-dimensional and Doppler ultrasound examination of the femoral arteries is useful for identifying femoral arterial obstruction.

ACCF/AHA/AAP recommendations for training in pediatric cardiology: A report of the American College of Cardiology Foundation/American Heart Association/American College of Physicians Task Force on Clinical Competence (ACC/AHA/AAP Writing Committee to Develop Training Recommendations for Pediatric Cardiology)

SUMMARY It is vital to the future intellectual health of cardiovascularmedicine and the welfare of pediatric patients with cardiovas-cular disease that all future pediatric cardiologists be familiarwith the principles and tools of research. Training in researchrequires the intense involvement of productive and establishedinvestigators. Those trainees preparing for a career in investi-gative cardiology require a carefully developed but flexibleeducational plan that will permit them to be successful in theirresearch careers over an extended period. REFERENCES 1. Sonnenblick EH, Ryan TI, Starke RD. Task force 7: training incardiovascular research. J Am Coll Cardiol 1995;25:25–8.2. Roberts R, Alexander RW, Loscalzo J, Williams RS. Task force 7:training in cardiovascular research. Available at: http://www.acc.org/clinical/training/cocats2.pdf 2002. Accessed August 10, 2004.3. NHLBI Task Force Report on Pediatric Cardiovascular Diseases.Available at: http://www.nhlbi.nih.gov/resources/docs/pediatric_cvd.pdf.Accessed August 10, 2004.

High-frequency percussive ventilation in a pediatric patient with hydrocarbon aspiration

Introduction: To describe ventilator management using a high-frequency percussive ventilator (HFPV), after other modes of mechanical ventilation failed. Design: Case series. Setting: Pediatric intensive care unit. Patients: Previously healthy 11-month-old male with severe aspiration pneumonitis from mineral oil. Interventions: The patient was initially placed on a conventional ventilator in a pressure-regulated volume-control mode but needed higher-than-normal pressures to maintain adequate ventilation. A decision was made to switch the patient to a pressure-control/pressure-support mode. At the end of the third day of pressure-control/pressure-support mode, a decision was made to attempt airway pressure-release ventilation. During a trial attempt, saturation levels deteriorated and a decision was made to place the patient on a high-frequency oscillator. The patient remained on this mode of ventilation for 6 days. On the sixth day, the chest radiograph showed a worsening of his pneumonia, and the patient started to deteriorate. A decision was made to try the HFPV in an attempt to mobilize secretions and any residual mineral oil. Immediately after initiating the HFPV and for 4 hrs thereafter, large amounts of secretions—including a thick, oily substance—were suctioned from the airways. Within 12–24 hrs, oxygenation improved dramatically and Fio2 was weaned. During the next 12 hrs, the patient was weaned off HFPV onto a conventional ventilator, and he was extubated 48 hrs after initiating HFPV. Conclusions: In this case, HFPV used as an alternative mode of ventilation successfully mobilized secretions that were otherwise unobtainable and that we believe led to the swift recovery of this child. HFPV should be given consideration as a mode of ventilation when mobilization of secretions is an issue.