Gravity Venous Drainage and the 3/8-Inch Venous Line: What Would Poiseuille Do?

The 1/2″ venous line has long been the drainage tubing diameter of choice for adult patients undergoing cardiac surgery. However, several programs use a smaller diameter venous line when used in conjunction with kinetic-assisted venous drainage or vacuum-assisted venous drainage. In 2014, our perfusion team made an institution-wide effort to miniaturize the cardiopulmonary bypass (CPB) circuit for children. One of our changes was the transition to a 3/8″ diameter venous line for drainage, even in our larger patients (up to 80 kg). We reviewed the current literature on this topic and delineated the various parameters required to be able to use the 3/8″ venous line with gravity drainage with the aim of using it on patients up to 115 kg with the appropriate venous reservoir. We have successfully used the 3/8″ venous line in more than 40 of our larger patients (35-90 kg) without the need for assisted venous drainage. We were able to reduce CPB prime from 625 ± 118 to 425 ± 52 mL before retrograde autologous priming (RAP)/venous autologous priming (VAP). The prime was further reduced to 325 ± 66 mL after RAP/VAP. Homologous blood utilization was reduced from 217 ± 311 mL to 27 ± 77 mL. Both results were statistically significant. We hypothesize that taking into account two of the parameters of Poiseuille's law, namely length and diameter, it is possible to safely drain large children and mid-size adults via gravity venous drainage and the 3/8″ venous line. This technique allows reducing prime volume, simplifies CPB circuits with increased safety and potentially reduces the need for homologous blood transfusion.

The Novel Use of a Low Prime Modified Ultrafiltration Apparatus in a 13-kg Jehovah's Witness Patient: A Case Report.

Modified ultrafiltration (MUF) is used in neonates and infants to reduce volume overload and increase oxygen-carrying capacity post cardiopulmonary bypass (CPB). In addition, it decreases edema, attenuates complementation activation and immunogenic response to CPB. Hemodilution in the pediatric patient has always been a challenge, countered in part by miniaturization of CPB circuits. We describe a case in which we maintained an acceptable hematocrit level greater than 24%, considered the nadir below which the adverse effects of hemodilution can become evident. We performed this by the novel use of an intravenous warming device (enFlow, Vyaire Medical, Mettawa, IL) to reduce the prime volume of our MUF circuit by more than 50%. We present the case and discuss the advantages and disadvantages of using a low-prime MUF circuit. We were able to conduct "bloodless" CPB, with the use of acute normovolemic hemodilution, miniaturization of the CPB and MUF circuits.

The Impact of Roller Pump vs. Centrifugal Pump on Homologous Blood Transfusion in Pediatric Cardiac Surgery.

Centrifugal pumps are considered to be less destructive to blood elements (1) when compared to roller pumps. However, their large prime volumes render them unsuitable as arterial pumps in heart lung machine (HLM) circuitry for children. In November of 2014, the circuit at Arnold Palmer Hospital, a Biomedicus BP-50 with kinetic assist venous drainage (KAVD) and 1/4″ tubing was converted to a roller pump in the arterial position with gravity drainage. Vacuum-assisted venous drainage (VAVD) was mounted on the HLM as a backup, but not used. Tubing was changed to 3/16″ in the arterial line in patients <13 kg. A retrospective study with a total of 140 patients compared patients placed on cardiopulmonary bypass (CPB) with Biomedicus centrifugal pumps and KAVD (Centrifugal Group, n = 40) to those placed on CPB with roller pumps and gravity drainage (Roller Group, n = 100). Patients requiring extra-corporeal membrane oxygenation (ECMO)/cardio-pulmonary support (CPS) or undergoing a hybrid procedure were excluded. Re-operation or circulatory arrest patients were not excluded. Prime volumes decreased by 57% from 456 ± 34 mL in the Centrifugal Group to 197 ± 34 mL in the Roller Group (p < .001). There was a corresponding increase in hematocrit (HCT) of blood primes and also on CPB. Intraoperative homologous blood transfusions also decreased 55% from 422 mL in the Centrifugal Group to 231 mL in the Roller Group (p < .001). The Society of Thoracic Surgeons--European Association for Cardio-Thoracic Surgery (STAT) categorized intubation times and hospital length of stay (LOS) for all infants showed a trend toward reduction, but was not statistically significant. Overall mortality was 5% utilizing the centrifugal configuration and 0% in the roller pump cohort. We demonstrated that the transition to roller pumps in the arterial position of the HLM considerably reduced our priming volume and formed a basis for a comprehensive blood conservation program. By maintaining higher HCTs on CPB, we were able to reduce intraoperative homologous blood transfusions.

Fontan Fenestration Closure Prior to Posterior Spinal Fusion in Patients With Single-Ventricle Heart Disease.

STUDY DESIGN: Case series. OBJECTIVE: To describe transcatheter closure of the Fontan fenestration prior to posterior spinal fusion in two children to prevent paradoxical venous air embolism during the operation. SUMMARY OF BACKGROUND DATA: Scoliosis is common among patients with single-ventricle congenital heart disease who have undergone Fontan operation and spinal surgery can offer physiologic benefits. Venous air embolism is a rare, but important reported complication during spinal surgery performed in the prone position. Patients with Fontan circulation can have significant right to left shunting via a patent Fontan fenestration that can increase the risk of paradoxical systemic embolization of any entrained venous air. METHODS: We retrospectively reviewed the charts of two patients with single-ventricle congenital heart disease who had undergone fenestrated Fontan operation and underwent transcatheter fenestration closure prior to spinal fusion. RESULTS: Two patients with Fontan circulation underwent successful transcatheter fenestration closure with Amplatzer Ductal Occluder II devices. Five to 6 months after closure, both underwent uncomplicated posterior spinal fusion. CONCLUSION: Transcatheter closure of the Fontan fenestration prior to spinal fusion in two with Fontan circulation and scoliosis is a rare, but important indication for fenestration closure that warrants emphasis. LEVEL OF EVIDENCE: N/A.

Transcatheter Patent Ductus Arteriosus Occlusion in Small Infants.

BACKGROUND: Transcatheter patent ductus arteriosus (PDA) occlusion is feasible in small infants and may improve lung function in symptomatic patients. We aimed to describe transcatheter PDA closure in small infants including predictors of technical success and rate of complication and to identify factors associated with improved respiratory status after closure. METHODS: All patients in the NICU at our center who were referred for transcatheter PDA occlusion between 1/2010 and 11/2014 were retrospectively identified. Relevant details were extracted. Additionally, a modification of the respiratory severity score (RSS) (FiO2 × mean airway pressure) was used to characterize degree of pulmonary support before and at intervals after catheterization. RESULTS: Twenty patients were identified with median age of 96 days (13-247) and weight of 3.1 kg (1.7-4.7). The PDA was type F morphology in 14 (70%) patients. The PDA was successfully occluded in 16 (80%) patients. Ratio of minimum PDA diameter/length was >0.5 in all unsuccessful attempts and <0.4 in all successful cases (P = .01). Of the 16 cases of occlusion, Amplatzer Vascular Plug II was used in 15 (94%). No deaths or pulse loss occurred. Five (25%) patients required blood transfusion and transfusion was associated with lower hemoglobin (P = .049), lower weight (P = .008), and lower aortic pressure (P = .04). Excluding 1 patient with significant congenital heart disease, the RSS improved at 3 days in 9 (60%) patients and at 7 days in 12 (80%) compared with preintervention value. Patient factors were not associated with improved RSS at 3 or 7 days. CONCLUSIONS: In our cohort of symptomatic infants, transcatheter PDA occlusion was successful in most and a ratio of minimum PDA diameter/length of <0.4 was predictive of technical success. Using a surrogate for pulmonary support, the majority of patients were on less support 7 days after closure.

The effect of epinephrine on coronary flow in the setting of a systemic-to-pulmonary artery shunt.

BACKGROUND: Indirect clinical evidence suggests that coronary blood flow (CBF) is altered in patients palliated with systemic-to-pulmonary artery shunts (SPSs). The addition of epinephrine may exert additional effects. METHODS: A total of 11 newborn piglets underwent placement of a 3.5- to 4-mm graft between the innominate artery and the pulmonary artery. Doppler probes measured flow continuously in the aorta (aortic flow [AoF]), pulmonary artery and left coronary artery at baseline (SPS closed), SPS open, and during epinephrine administration (SPS closed and open). Each animal served as its own control. Systolic and diastolic CBF, resistance (coronary vascular resistance index [CVRI]), and myocardial oxygen supply demand ratio were calculated. RESULTS: Opening the SPS increased AoF and decreased systolic and diastolic pressure from baseline, with and without the presence of epinephrine. The CBF and CVRI decreased on opening the SPS in the presence of epinephrine. The decrease occurred only in diastole and was proportional to pulmonary-to-systemic flow ratio (Qp/Qs). Epinephrine infusion itself reduced CVRI with SPS closed, but there was little further decrease on opening SPS. Myocardial oxygen supply-demand ratio decreased on opening SPS at baseline and with epinephrine. CONCLUSIONS: This study suggests that SPS decreases CBF, especially in the presence of a higher Qp/Qs and epinephrine. The mechanism is largely due to the decrease in diastolic pressure and the inability of the coronary arteries to compensate with vasodilation.

Effects of phentolamine infusion during selective cerebral perfusion in neonatal piglets.

BACKGROUND: An optimal selective cerebral perfusion protocol in pediatric cardiac surgery is unknown. Phentolamine is frequently used in pediatric cardiopulmonary bypass. We sought to determine the effects of continuous phentolamine infusion during selective cerebral perfusion. METHODS: Twenty-seven neonatal piglets (3.38 ± 0.32 kg) were randomly assigned to 3 groups; sham (n = 7, anesthesia alone, no surgery or bypass), control (n = 10, saline infusion), or experimental (n = 10, phentolamine infusion 0.1 mg/kg per hour). Animals underwent 90 minutes of selective cerebral perfusion. Cerebral vascular resistance index (CVRI) and metabolic rate of oxygen (CMRO2) were determined every 15 minutes. Standardized sections of hippocampus, basal ganglia, and neo-cortex were obtained. Tissue samples were stained for caspase-3 and analyzed for positive apoptotic cell count. Data were analyzed with repeated measures and one-way analysis of variance. RESULTS: The CVRI tended to increase over time in the control group and decrease over time in the experimental group, but difference was not statically significant (0.46 ± 0.24 vs 0.39 ± 0.10 mm Hg × min × kg(2/3)/mL, p = 0.15). Mean CMRO2 was higher in the control group compared with the experimental group (0.90 ± 0.27 vs 0.59 ± 0.12 mLO2/min × kg(2/3), p = 0.005) and decreased over time in both groups. The percentage of caspase-3 positive cells was significantly different among regions (hippocampus = 16.9 ± 8.8; basal ganglia = 14.6 ± 7.5; neocortex = 10.8 ± 6.3; p < 0.0001) but not significantly different among sham (11.8% ± 2.68%), control (14.4% ± 2.24%), and experimental (15.5% ± 2.24%) groups. CONCLUSIONS: A continuous infusion of phentolamine during selective cerebral perfusion significantly decreases CMRO2 and tends to decrease CVRI when compared with control. At the dose studied and at the time of tissue sampling, phentolamine does not appear to decrease apoptosis during or early after selective cerebral perfusion.

Cardiopulmonary bypass in an infant with a recent history of malaria.

Severe malarial infection is associated with impaired cardiac function. We report a child who underwent repair of tetralogy of Fallot two weeks after being treated for malaria. The postoperative course was complicated by impaired left ventricular function. The pathogenesis of malaria is discussed as well as the potential complications of cardiopulmonary bypass (CPB).

Alternative anticoagulation during cardiovascular procedures in pediatric patients with heparin-induced thrombocytopenia.

Patients with heparin-induced thrombocytopenia (HIT) that require anticoagulation for cardiovascular procedures represent a challenging and high-risk group. Bivalirudin and argatroban have been successfully used as alternative anticoagulants in adult patients with HIT. There have been few experiences published involving the pediatric population and controversy exists regarding the properties and optimal dosing of these drugs. This report describes the experience of managing two pediatric patients with HIT that underwent cardiovascular procedures requiring anticoagulation. Bivalirudin was used in both cases for anticoagulation during cardiopulmonary bypass, while argatroban was used without complications during cardiac catheterization. A description of perfusion and anticoagulation protocols is included.

Perioperative hyperglycemia: effect on outcome after infant congenital heart surgery.

BACKGROUND: Studies demonstrate that cardiopulmonary bypass (CPB) causes intraoperative and postoperative hyperglycemia. Hyperglycemia has been associated with morbidity and mortality after infant cardiac surgery. We studied the effects on early postoperative outcomes of glucose (GLU) changes during and after pediatric cardiac surgery. METHODS: The records of 144 infants less than 10 kg who underwent CPB for a variety of congenital cardiac procedures were reviewed. The GLU values (at multiple intervals during and after surgery), age, weight, CPB time, ultrafiltration volume, and risk adjustment for congenital heart surgery (RACHS-1) score were recorded. Univariate and multivariate linear and binary logistic regression were used to examine the dependence of the composite outcome mortality or postoperative infection, the mechanical ventilation time (VENT time), and the length of stay (LOS), on these variables. RESULTS: The RACHS-1 score was the only significant predictor of the composite variable "mortality or infection" (p = 0.008). Glucose at any time was not a significant factor predicting this outcome. Lower pre-CPB GLU, younger age, and higher RACHS-1 score were significant predictors of greater LOS and VENT time. CONCLUSIONS: In this study, post-CPB and postoperative hyperglycemia were not risk factors for postoperative morbidity and mortality after infant cardiac surgery.

Dexmedetomidine/ketamine for diagnostic cardiac catheterization in a child with idiopathic pulmonary hypertension.

The use of a combination of dexmedetomidine and ketamine to provide procedural sedation in a 12-year old boy with a diagnosis of idopathic pulmonary hypertension and a behavioral disorder, undergoing diagnostic cardiac catheterization, is presented. Following a loading dose of ketamine one mg/kg and dexmedetomidine one mcg/kg, an infusion of dexmedetomidine at one mcg/kg/hr was used with the patient breathing spontaneously. Stable hemodynamics were observed throughout the procedure and pulmonary vascular resistance was measured under three conditions. The dexmedetomidine infusion was continued for two hours post-catheterization, facilitating a smooth emergence.

Continuous incisional infusion of local anesthetic in pediatric patients following open heart surgery.

AIM: To determine the efficacy and safety of a continuous subcutaneous local anesthetic (LA) infusion in pediatric patients following open heart surgery. BACKGROUND: The use of a continuous LA infusion has been shown to be beneficial following adult cardiac surgery. To date there are no studies in the pediatric population. METHODS/MATERIALS: Using a prospective, randomized, and double blind design, we compared LA, either 0.25% levobupivacaine or bupivacaine (Treatment Group) to saline (Placebo Group) delivered subcutaneously via a continuous infusion for 72 h after open heart surgery in 72 patients. Requirements for postoperative analgesics and pain scores were recorded for 72 h and plasma levels of local anesthetic were measured. Secondary outcomes measures included time to first oral intake, time to first bowel movement, time to urinary catheter removal, length of stay, requirements for antiemetics and additional sedation. RESULTS: Total morphine requirements over the first 24 h were less in the Treatment Group than the Placebo Group (0.05 mg x kg(-1) vs 0.2 mg x kg(-1), P = 0.007); this was true for all patient groups except those patients weighing less than 6.3 kg. The number of patients requiring no morphine was greater in the Treatment Group (7/35 vs 1/37, P = 0.02). The Treatment Group also received less midazolam, lorazepam, and ketorolac than the Placebo Group over 72 h due to the reduced clinical need for these agents in patients weighing less than 31 kg. There were no differences in secondary outcomes. CONCLUSIONS: A continuous incisional infusion of LA reduced postoperative analgesic requirement and sedative use in pediatric patients undergoing a median sternotomy incision. Dosed at a maximum rate of 0.4 mg x kg(-1) x h(-1), a continuous incisional infusion of LA is effective and safe for up to 72 h, with plasma levels of local anesthetic well below the toxic threshold.

Initial experience with dexmedetomidine for diagnostic and interventional cardiac catheterization in children.

BACKGROUND: Children undergoing diagnostic and interventional cardiac catheterization require deep sedation or general anesthesia (GA). Dexmedetomidine, a selective alpha-2 adrenergic agonist, has sedative, analgesic and anxiolytic properties without respiratory depression. These characteristics make it potentially suitable as a sedative agent during diagnostic procedures in children. We report our experience using dexmedetomidine in 20 children aged 3 months to 10 years undergoing cardiac catheterization. METHODS: Following a midazolam premedication, intravenous access was secured facilitated by the inhalation of sevoflurane in oxygen. A loading dose of 1 microg x kg(-1) dexmedetomidine was administered over 10 min followed by an initial infusion rate of 1 microg x kg(-1) x h(-1). Nasal cannulae were applied, allowing endtidal CO2 monitoring with the patients breathing spontaneously. Hemodynamic parameters, Bispectral Index Score (BIS) and sedation score were measured every 5 min. Patient movement or evidence of inadequate sedation were treated with propofol (1 mg x kg(-1)). The dexmedetomidine infusion rate was titrated to the level of sedation to a maximum of 2 microg x kg(-1) x h(-1) to maintain a sedation score of 4-5 and a BIS value <80. RESULTS: Five patients (25%) had some movement on local infiltration or groin vessel access. This did not necessitate restraint or result in difficulty securing vascular access. No patients failed sedation that required the addition of another sedative agent or conversion to GA; eight patients were sedated with dexmedetomidine alone; however, 12 (60%) patients did receive a propofol bolus at some time during the procedure due to movement, increasing BIS value or in anticipation of stimulation. There were no incidences of airway obstruction or respiratory depression. In all cases the heart rate and blood pressure remained within 20% of baseline. No patient required treatment for profound bradycardia or hypotension. The average infusion rate for dexmedetomidine following the loading dose was 1.15 (+/-0.29)microg x kg(-1) x h(-1) (range 0.6-2.0 microg x kg(-1) x h(-1)). CONCLUSIONS: This initial experience showed dexmedetomidine, with or without the addition of propofol, may be a suitable alternative for sedation in spontaneously breathing patients undergoing cardiac catheterization.

Severe stenosis of a long tracheal segment, with agenesis of the right lung and left pulmonary arterial sling.

A baby presented at term with respiratory distress was managed with extracorporeal membrane oxygenation. Bronchoscopy revealed tracheal hypoplasia, complete tracheal rings, and agenesis of the right main bronchus. Echocardiography showed a left pulmonary arterial sling arising from the proximal part of the right pulmonary artery. Cardiac catheterization demonstrated abnormal pulmonary vasculature in the left lung which would have prevented survival, even after surgical repair. Diagnostic catheterization was important in delineating the anatomy, and aided in the decision not to proceed with surgical repair.

Anesthetic management of conjoined twins presenting for palliative open-heart surgery.

A set of dicephalous parapagus twins was born at 36 wk gestational age. Twin A had complex congenital heart disease in the form of a single ventricle that would be fatal without surgical intervention. Twin B had normal intracardiac anatomy. The twins were deemed surgically inseparable and the parents requested palliative open-heart surgery on Twin A. The twins shared a common circulatory system to the lower half of the body so that physiological manipulations in one twin adversely affected the other's hemodynamic condition. Twin A underwent successful single ventricle palliation; however, after a prolonged hospitalization, the infants died secondary to severe respiratory disease in Twin B.

Efficacy of aprotinin in children undergoing craniofacial surgery.

OBJECT: This prospective, randomized, placebo-controlled, double-blind trial was undertaken to assess the efficacy of aprotinin in reducing the need for blood transfusions in 39 children undergoing reconstructive craniofacial surgery. METHODS: Two demographically similar groups--a total of 39 patients with a mean age of 1.2 +/- 1.2 years--were studied. The efficacy of aprotinin (240 mg/m2 administered intravenously over 20 minutes, followed by infusions of 56 mg/m2/hr) was compared with that of an equal infusion of 0.9% saline (placebo). Patients in the aprotinin group received less blood per kilogram of body weight than patients in the placebo group (32 +/- 25 ml/kg compared with 52 +/- 34 m/kg, respectively; p = 0.04). Those patients in whom aprotinin was administered experienced less change in their hematocrit levels during surgery (aprotinin -33 +/- 13% compared with placebo -44 +/- 9%, p = 0.01). Each patient underwent a transfusion as per study protocol, and there was no significant change in hematocrit levels from the beginning to the end of surgery. The surgical faculty judged blood loss in patients in the aprotinin group to be significantly less than usual (p = 0.03). The use of aprotinin was also associated with reduced blood transfusion requirements during the first 3 postoperative days (p = 0.03). There was no adverse event reported in either the aprotinin or placebo group. CONCLUSIONS: Aprotinin decreased blood transfusion requirements in pediatric patients undergoing craniofacial reconstruction, thereby reducing the risks associated with exposure to banked blood components.

Low-dose ketorolac improves analgesia and reduces morphine requirements following posterior spinal fusion in adolescents.

PURPOSE: To determine if low-dose ketorolac would improve analgesia while minimizing unwanted side effects in adolescents following posterior spinal fusion (PSF). METHODS: A prospective randomized double-blind placebo-controlled trial assessed the analgesic effects of low-dose ketorolac following PSF. Thirty-five adolescents aged 11-17 yr were randomly assigned to receive placebo or 0.5 mg x kg(-1) ketorolac (maximum of 15 mg) six hourly postoperatively for 36 hr in conjunction with standard morphine patient controlled analgesia (PCA). Pain and sedation were assessed twice daily for the first three postoperative days (POD). The incidence of side effects related to both non-steroidal anti-inflammatory agents and opioids were recorded. RESULTS: Adolescents in the ketorolac group received an average dose of 0.2 mg x kg(-1) (average exposure 1.2 mg x kg(-1)), had lower pain scores on POD one and two (P < 0.05) and consumed less morphine in the postanesthesia care unit and on POD two. There was no difference in the incidence of pruritus, nausea, vomiting or constipation, but patients in the ketorolac group tolerated activity better on POD one (P < 0.05). There were no differences between groups with regard to postoperative blood loss or transfusion requirements. Fourteen patients were followed for two years and the incidence of curve progression, hardware failure or back pain at final follow-up was not different. CONCLUSION: Low-dose ketorolac in conjunction with morphine PCA improved the quality of analgesia and reduced morphine requirements following PSF compared to placebo without increasing the incidence of non-steroidal anti-inflammatory side effects.