A human model of bilateral pulmonary vein sampling to assess the effects of one-lung ventilation on neutrophil function.

BACKGROUND: Neutrophil activation drives lung complications after cardiopulmonary bypass (CPB). Evidence suggests the healthy, ventilated lung may beneficially re-condition pro-inflammatory neutrophils. However, evidence in humans is lacking, due to a paucity of good models. CPB with simultaneous central venous and bilateral pulmonary vein sampling provides an opportunity to model effects of one-lung ventilation. The study's primary objectives were to establish a model of intra-operative, bilateral pulmonary vein sampling and to determine whether neutrophil function differed after passing through inflated or deflated lungs. METHODS: Seventeen patients having "on pump" coronary artery bypass grafting (CABG) with one-lung ventilation (in two cohorts with tidal volume 2ml kg-1 and FiO2 0.21, or tidal volume 4 ml kg-1 and FiO2 0.5 respectively) were recruited. Cohort 1 consisted of 9 patients (7 male, median age 62.0 years) and Cohort 2 consisted of 8 male patients (median age 65.5 years). Recruitment was via prospective screening of scheduled elective and non-elective CABG procedures with cardiopulmonary bypass. Each patient had five blood samples taken-central venous blood pre-operatively; central venous blood pre-CPB; central venous blood post-CPB; pulmonary venous blood draining the ventilated lung post-CPB; and pulmonary venous blood draining the deflated lung post-CPB. Neutrophil phagocytosis and priming status were quantified. Plasma cytokines were measured. RESULTS: Phagocytosis and priming were not significantly different in neutrophils returning from the ventilated lung as compared to the non-ventilated lung. Plasma IL-6, IL-8 and IL-10 were significantly elevated by CPB. CONCLUSIONS: The intra-operative, bilateral pulmonary vein sampling model provides unique opportunities to assess biological effects of interventions to one lung, with the other lung acting as an internal control. Single-lung ventilation during CPB had no significant effects on neutrophil function.

Managing a Mycotic Thoracoabdominal Aneurysm: The Importance of Molecular Diagnostics.

Pneumococcal mycotic aneurysms are rare and associated with significant mortality and morbidity. Early intravenous antibiotic therapy and surgical intervention is the mainstay of treatment. Pneumococci frequently autolyze in blood cultures, making microbiological diagnosis challenging. We present the case of a man in his mid 70s with multiple thoracoabdominal mycotic aneurysms. Surgery was performed to a threatening saccular aortic arch aneurysm. Samples were sent for microbiological analysis and all were culture negative. The samples were then referred for bacterial 16S ribosomal RNA sequencing, which revealed evidence of infection with Streptococcus pneumoniae.

Bucket-handle repair of a tear in the bronchus intermedius with an intercostal muscle flap.

As previously well described in the literature, the intercostal muscle (ICM) flap can be used to buttress bronchial stumps following lung resection. We describe a harvesting technique of ICM flap which enabled a bi-lobectomy to be avoided in a patient with poor pulmonary function. The Key to this technique is the preservation of the neurovascular bundle. Therefore the flap is not divided anteriorly thereby differentiating it from any previous technique described.We have called it the 'bucket handle' technique, which was used to repair an intra-operative tear in bronchus intermedius. Its efficacy was tested to the full when the patient developed severe adult respiratory distress syndrome (ARDS) secondary to pseudomonas pneumonia and required high-pressure mechanical ventilation. This case demonstrates that ICM flap is an effective buttress to bronchial stumps or repairs and offers reassurance for optimal outcome due to its intact vascular pedicle.

Hemodynamic correlates of serum cortisol in neonates after cardiopulmonary bypass.

OBJECTIVES: To document preoperative and early postoperative serum cortisol levels among a group of neonates with complex congenital heart disease undergoing cardiopulmonary bypass surgery and to describe the relationship between serum cortisol and hemodynamic variables in the early postoperative period. DESIGN: Prospective observational substudy conducted within a randomized controlled trial. SETTING: Tertiary-care pediatric cardiac intensive care unit. PATIENTS: : We consecutively enrolled neonates undergoing a modified Norwood procedure or repair of interrupted aortic arch with ventricular septal defect in a randomized, placebo-controlled trial of triiodothyronine replacement. Methylprednisolone (30 mg/kg intravenously) was administered at anesthetic induction. MEASUREMENTS AND MAIN RESULTS: We measured serum cortisol preoperatively and at 24 and 48 hrs postoperatively. Atrial filling pressures were documented 24 and 48 hrs after surgery. Oxygen consumption was measured and cardiac index was calculated 48 hrs after surgery. Spearman's correlation and linear regression were used to examine the relationship between serum cortisol and postoperative variables. Thirty-eight patients met eligibility criteria. Median serum cortisol levels 24 and 48 hrs postoperatively were 5.0 µg/dL (range 0.4-74.0) and 4.0 µg/dL (range 0.3-17.0), respectively (p = not significant). Greater atrial filling pressures were correlated with higher serum cortisol levels 24 hrs (r = .42, p = .019) and 48 hrs (r = .46, p = .022) after surgery. A lower cardiac index was correlated with higher serum cortisol levels 48 hrs postoperatively (r = -.49, p = .039), and this relationship remained significant after controlling for inotrope score, treatment with triiodothyronine, and atrial filling pressure in bivariate models. Systolic and diastolic BP did not correlate with serum cortisol at 24 or 48 hrs. CONCLUSIONS: Serum cortisol levels were low in the majority of subjects, although a wide range was observed. Higher cortisol levels were associated with greater atrial filling pressures and a lower cardiac index. The relationship between serum cortisol and cardiovascular performance after cardiopulmonary bypass in infants warrants further evaluation.

The influence of comorbidity on the risk of access-related bacteremia in chronic hemodialysis patients.

Access-related bacteremia is an important cause of morbidity in chronic hemodialysis patients. The incidence of bacteremia is higher in patients dialyzing through a tunneled central venous catheter (TCVC) compared with an arteriovenous fistula (AVF). Our aim was to explore if this is explained by patient comorbidity. Two groups of chronic hemodialysis outpatients were compared: all patients who dialyzed through a TCVC at any time during 2003 and were fit enough to subsequently have a functioning AVF or renal transplant even if it was after 2003 (Group 1; n=93); and all patients who dialyzed through a TCVC in 2003 and were not fit enough to have a functioning AVF or renal transplant (Group 2; n=119). Episodes of bacteremia (n=71) were identified and those not related to access were excluded. Patients in Group 1 were younger than Group 2 (57.5 years vs. 64.8 years; P=0.001). The incidences of bacteremia in Groups 1 and 2 were, respectively, 0.31 and 0.44 episodes per 1000 patient days while dialyzing through an AVF (P=0.77), and 2.21 and 2.27 per 1000 days while dialyzing through a TCVC (P=0.91). The 3-year actual survival from January 1, 2003 to January 1, 2006 was significantly higher in Group 1 than in Group 2 (80.6% vs. 26.1%; P<0.0001) confirming the higher comorbidity of the patients in Group 2. Patients dialyzing through a TCVC (compared with an AVF) have a significantly higher risk of access-related bacteremia, irrespective of comorbidity.

Cerebral perfusion and oxygenation after the Norwood procedure: comparison of right ventricle-pulmonary artery conduit with modified Blalock-Taussig shunt.

OBJECTIVE: The proposed physiologic advantage of the modified Norwood procedure using a right ventricle-pulmonary artery conduit to supply pulmonary blood flow, compared with a modified Blalock-Taussig shunt, is reduced runoff from the systemic-to-pulmonary circulation during diastole, resulting in a higher diastolic blood pressure and improved systemic perfusion. We hypothesized that the modified Norwood procedure is associated with improved cerebral perfusion and oxygenation. METHODS: Transcranial Doppler sonography and near-infrared spectroscopy were performed in neonates undergoing the Norwood procedure with either a modified Blalock-Taussig shunt (n = 14) or right ventricle-pulmonary artery conduit (n = 13). RESULTS: Diastolic blood pressure was significantly higher in the right ventricle-pulmonary artery group at 6 hours after bypass (46 +/- 7 vs 40 +/- 4 mm Hg; P = .03), on postoperative day 1 (45 +/- 6 vs 37 +/- 5 mm Hg; P = .002), and on postoperative day 2 (46 +/- 7 vs 37 +/- 4 mm Hg; P = .001). Cerebral diastolic blood flow velocity did not differ significantly between groups at any time point or over time, but cerebral systolic blood flow velocity was higher over time in the Blalock-Taussig group (P = .01). No significant differences in regional cerebral oxygen saturation were found between groups at baseline or after bypass. Blood flow velocities and cerebral oxygen saturation did not differ significantly according to use of regional low-flow perfusion. CONCLUSIONS: The higher diastolic blood pressure after the modified Norwood procedure is not associated with higher cerebral blood flow velocities or regional cerebral oxygen saturation. This may imply an equal vulnerability to the cerebral injury associated with hemodynamic instability in the early postoperative period.

Extracorporeal membrane oxygenation support of a neonate with percutaneous femoral arterial cannulation.

We describe a neonate with hypoplastic left heart syndrome supported with venoarterial extracorporeal membrane oxygenation with a femoral arterial cannula. A 6-French straight sheath was percutaneously placed in the right femoral artery using the Seldinger technique. Adequate extracorporeal membrane oxygenation flows were achieved, and the patient was successfully de-cannulated. Femoral arterial cannulation in neonates is technically feasible and provides an alternative site for extracorporeal membrane oxygenation cannulation.

Initial experience with fenoldopam after cardiac surgery in neonates with an insufficient response to conventional diuretics.

OBJECTIVE: Fenoldopam, a selective dopamine-1 receptor agonist, causes systemic vasodilation and increased renal blood flow and tubular sodium excretion. We hypothesized that urine output would improve when fenoldopam was added to conventional diuretic therapy after neonatal cardiopulmonary bypass. DESIGN: Retrospective cohort study using a time-series design. SETTING: Pediatric cardiac intensive care unit. PATIENTS: All neonates who received fenoldopam to promote diuresis after cardiac surgery requiring cardiopulmonary bypass from February 2002 through December 2004. INTERVENTIONS: Fenoldopam infusion for inadequate urine output despite conventional diuretics. MEASUREMENTS: Demographics, diagnostic information, and surgical procedures were recorded. Urine output, fluid balance, inotrope scores, diuretic doses, and other clinical variables that may influence diuresis were recorded for the 24-hr period immediately preceding fenoldopam initiation and during the initial 24 hrs of drug administration. MAIN RESULTS: A total of 25 neonates received fenoldopam to promote diuresis after the modified Norwood (n = 14), arterial switch (n = 4), or other operations (n = 7). Heart rate, conventional diuretic dosing, and fluid intake were similar during the 24-hr periods of conventional therapy and fenoldopam use (p = not significant for all), whereas inotrope scores decreased during the study (p = .021). There was a small but statistically significant increase in blood pressure during the 48-hr study period. Median urine output was 3.6 mL x kg(-1) x hr(-1) (range, 0.2-7.2 mL x kg(-1) x hr(-1)) during the 24-hr period of conventional therapy and 5.8 mL x kg(-1) x hr(-1) (range, 1.6-11.7 mL x kg(-1) x hr(-1)) during the initial 24 hrs of fenoldopam administration (Wilcoxon's signed-rank test, p = .001). CONCLUSIONS: Fenoldopam may improve urine output in neonates who are failing to achieve an adequate negative fluid balance despite conventional diuretic therapy after cardiac surgery and cardiopulmonary bypass. This study is limited by its retrospective design and the possibility that urine output improved spontaneously during the treatment period. A randomized, placebo-controlled clinical trial will be required to confirm these findings.

A randomized, double-blind, placebo-controlled pilot trial of triiodothyronine in neonatal heart surgery.

OBJECTIVE: This study was undertaken to evaluate the effect of triiodothyronine replacement on the early postoperative course of neonates undergoing aortic arch reconstruction. METHODS: We performed a randomized, double-blind, placebo-controlled trial of triiodothyronine supplementation in neonates undergoing either a Norwood procedure or two-ventricle repair of interrupted aortic arch and ventricular septal defect. Patients were assigned to receive a continuous infusion of triiodothyronine (0.05 micro/kg/h) or placebo for 72 hours after cardiopulmonary bypass. Primary end points were a composite clinical outcome score and cardiac index at 48 postoperative hours. RESULTS: We enrolled 42 patients (triiodothyronine n = 22, placebo n = 20). Baseline characteristics were similar in the treatment groups. Study drug was discontinued prematurely because of hypertension (n = 1) and ectopic atrial tachycardia (n = 1), both cases in the triiodothyronine group. Free and total triiodothyronine levels were higher in the triiodothyronine group than in the placebo group at 24, 48, and 72 postoperative hours (P < .001). The median clinical outcome scores were 2.0 (range 0-4) with triiodothyronine and 2.0 (range 0-7) with placebo (P = .046). Compared with those in the placebo group, neonates assigned to triiodothyronine had shorter median time to negative fluid balance (2.0 vs 2.5 days, P = .027). Cardiac index values were 2.11 +/- 0.64 L/min x m2 with triiodothyronine and 2.05 +/- 0.72 L/min x m2 with placebo (P = .81). Heart rate and diastolic blood pressure were not influenced by triiodothyronine supplementation, but systolic blood pressure was higher in the triiodothyronine group (P < .001). No serious adverse events were attributed to triiodothyronine administration. CONCLUSION: Triiodothyronine supplementation was safe and resulted in more rapid achievement of negative fluid balance after aortic arch reconstruction. Cardiac index at 48 hours was not significantly improved.

Extracorporeal membrane oxygenation support of the Fontan and bidirectional Glenn circulations.

BACKGROUND: Extracorporeal membrane oxygenation can provide effective mechanical circulatory support for the failing circulation in children. Patients with failing Fontan and bidirectional Glenn physiology present additional challenges both for extracorporeal membrane oxygenation cannulation and support. We report our institutional experience in patients with cavopulmonary connections who received extracorporeal membrane oxygenation. METHODS: We performed a retrospective review of 20 patients with cavopulmonary connections (14 Fontan and 6 bidirectional Glenn) who were supported with extracorporeal membrane oxygenation from a single, large pediatric tertiary care center. RESULTS: Of the 20 patients, ten were supported and decannulated successfully (50%) (two after cardiac transplantation), but only six (30%) are alive at follow-up. Of the 14 Fontan patients, seven (50%) were withdrawn from extracorporeal membrane oxygenation or died within 48 hours of decannulation due to lack of myocardial recovery or severe neurologic injury. All four adult-sized (> 40 kg) Fontan patients were withdrawn from extracorporeal support. The seven Fontan patients who were successfully decannulated survived to discharge, and five (35.7%) are alive at follow-up (median 35 months; range, 7 to 140 months). Of the six bidirectional Glenn patients, five died before hospital discharge and the lone survivor has neurologic injury at follow-up. CONCLUSIONS: Patients with failing Fontan and bidirectional Glenn physiology present significant challenges to successful extracorporeal membrane oxygenation support. While the morbidity and mortality rates are high, there are select patients for whom extracorporeal support can be effective and lifesaving as a short-term resuscitative intervention.

Cardiac catheterization of patients supported by extracorporeal membrane oxygenation.

OBJECTIVES: The goal of this study was to describe the clinical outcomes of patients undergoing cardiac catheterization while supported with extracorporeal membrane oxygenation (ECMO). BACKGROUND: Extracorporeal membrane oxygenation is an important mechanical support for the failing circulation. There are diagnostic and therapeutic indications for cardiac catheterization in patients on ECMO, but no large series has been reported. METHODS: We performed a retrospective review of the indications and outcomes of patients catheterized on ECMO from a single, large pediatric tertiary care center. RESULTS: At our institution, 192 patients with cardiac disease have undergone a total of 216 courses of ECMO; 60 catheterizations were performed on 54 patients (28%). Indications for catheterization included assessment of surgical repair (21 patients), left heart decompression (12 patients), myocarditis/cardiomyopathy assessment (10 patients), non-post-operative hemodynamic assessment (8 patients), planned catheter-based interventions (6 patients), and arrhythmia ablation (3 patients). An intervention was undertaken either during or after 50 of the catheterizations (83%); 29 occurred at catheterization, 17 in the operating room (OR), and 4 both during catheterization and in the OR. Complications during catheterization were two myocardial perforations that were treated with pericardial drains (3%). Overall outcomes included successful decannulation of 39 patients, survival to hospital discharge of 26 (48%) patients, and longer-term survival of 23 (43%) patients (median follow-up, 35 months; range, 1 to 180 months). Fifteen patients were withdrawn from ECMO support due to severe neurologic impairment or lack of myocardial recovery. CONCLUSIONS: Cardiac catheterization can be performed safely on patients supported with ECMO. Catheterization during ECMO enables the diagnosis of residual lesions and can facilitate important therapeutic interventions.