Luis Zabala

Altered hematologic profiles following donor right hepatectomy and implications for perioperative analgesic management

Living liver donors for adult liver transplant recipients undergo extensive liver resection. Partial donor hepatectomies may alter postoperative drug metabolism and hemostasis; thus, the risks and the benefits of pain management for this unique patient population may need to be reassessed. The safety and efficacy of combined epidural analgesia and field infiltration in our initial living liver donor group are presented. A thoracic epidural catheter was placed before general anesthesia in 2 female and 6 male donors (44.2 ± 11.3 years old, mean ± standard deviation [SD], range 26–56). At the end of surgery, incisions were infiltrated (bupivacaine 0.25%), and an epidural infusion was used (bupivacaine 0.1% + hydromorphone hydrochloride 0.02%). Clinical outcomes were followed for 5 days. The time sequence of pain intensity on a 0–10 visual analog scale clustered into 3 phases, the intensity of which differed significantly from each other (2.2 ± 0.6, 0.69 ± 0.2, and 2.37 ± 0.3 respectively, P = 0.028). Right shoulder pain was observed in 75% of the donors. Sedation, pruritus, and nausea were minimal. Consistently maximal international normalized ratio elevation occurred at 17.6 ± 7 hours postoperatively, then slowly declined. Platelet counts were lowest on day 3. No neurologic injury or local anesthetic toxicity was observed. This 2‐site approach provided effective, safe, postoperative analgesia for our donors. Universally, coagulopathy ensued, indicating a potentially increased risk for epidural hemorrhage at epidural catheter removal and mandating close postoperative neurologic and laboratory monitoring. Research is needed to advance the understanding of postoperative coagulopathy and hepatic dysfunction in these donors to further optimize their perioperative management, including that of analgesia. (Liver Transpl 2004;10:363–368.)

Cardiac organ donor management

There is a critical shortage of donor organs. According to the United Network for Organ Sharing (UNOS), 20% of organs are discarded after procurement. Many of these may be potentially salvageable. Brain death is particularly detrimental to cardiac function. The initial sympathetic storm can produce direct myocardial injury. The ensuing spinal shock reduces global oxygen delivery. There is a change to anaerobic metabolism due to global mitochondrial dysfunction. Diabetes insipidus worsens hypovolemia and thyroid deficiency impairs cardiac function. Inadequate replacement of blood loss from trauma and coagulopathy worsens anemia and oxygen delivery. In the mid-1990s, the Papworth Hospital group in the UK advocated early invasive hemodynamic monitoring and administration of a ‘hormonal cocktail’, consisting of triiodothyronine (T3), vasopressin, methylprednisolone and insulin. This has been widely accepted and is endorsed by UNOS. Ventricular function, volume status and adequacy of resuscitation should be guided by invasive monitoring and serial echocardiography. Dopamine or epinephrine is used for inotropic support. If hypotension persists, vasopressin should be added which may allow reduction of inotropes. Donor lung function and ventilation should be optimized. Recently, two large retrospective studies have shown that, with aggressive pharmacological and hormonal resuscitation, a significant increase in the number and quality of organs harvested can be achieved.

Cyanotic congenital heart disease (CCHD): focus on hypoxemia, secondary erythrocytosis, and coagulation alterations

Children with cyanotic congenital heart disease (CCHD) have complex alterations in their whole blood composition and coagulation profile due to long‐standing hypoxemia. Secondary erythrocytosis is an associated physiological response intended to increase circulating red blood cells and oxygen carrying capacity. However, this response is frequently offset by an increase in whole blood viscosity that paradoxically reduces blood flow and tissue perfusion. In addition, the accompanying reduction in plasma volume leads to significant deficiencies in multiple coagulation proteins including platelets, fibrinogen and other clotting factors. On the one hand, these patients may suffer from severe hyperviscosity and subclinical ‘sludging’ in the peripheral vasculature with an increased risk of thrombosis. On the other hand, they are at an increased risk for postoperative hemorrhage due to a complex derangement in their hemostatic profile. Anesthesiologists caring for children with CCHD and secondary erythrocytosis need to understand the pathophysiology of these alterations and be aware of available strategies that lessen the risk of bleeding and/or thrombosis. The aim of this review is to provide an updated analysis of the systemic effects of long‐standing hypoxemia in children with primary congenital heart disease with a specific focus on secondary erythrocytosis and hemostasis.

Bispectral index in a 3-year old undergoing deep hypothermia and circulatory arrest.

We report a 3‐year‐old girl who presented with Scimitar syndrome and underwent hypothermic circulatory arrest for correction of anomalous pulmonary veins and an atrial septal defect. In this case the Bispectral Index (BIS) correlated significantly with the gradual onset of hypothermia and circulatory arrest. However, BIS remained low during the rewarming phase of cardiopulmonary bypass, in spite of adequate pump flows and stable haemodynamics. We postulate that this significant lag in BIS during the rewarming phase of deep hypothermic circulatory arrest may represent neuronal bewilderment or perhaps stunning, and differs from previous studies that show significant increase in BIS during rewarming from mild hypothermia.

Impact of protamine dose on activated clotting time and thromboelastography in infants and small children undergoing cardiopulmonary bypass.

To study the effect of two protamine‐dosing strategies on activated clotting time (ACT) and thromboelastography (TEG).

Transesophageal doppler measurement of renal arterial blood flow velocities and Indices in children

BACKGROUND: Doppler-derived renal blood flow indices have been used to assess renal pathologies. However, transesophageal ultrasonography (TEE) has not been previously used to assess these renal variables in pediatric patients. In this study, we (a) assessed whether TEE allows adequate visualization of the renal parenchyma and renal artery, and (b) evaluated the concordance of TEE Doppler-derived renal blood flow measurements/indices compared with a standard transabdominal renal ultrasound (TAU) in children. METHODS: This prospective cohort study enrolled 28 healthy children between the ages of 1 and 17 years without known renal dysfunction who were undergoing atrial septal defect device closure in the cardiac catheterization laboratory. TEE was used to obtain Doppler renal artery blood velocities (peak systolic velocity, end-diastolic velocity, mean diastolic velocity, resistive index, and pulsatility index), and these values were compared with measurements obtained by TAU. Concordance correlation coefficient (CCC) was used to determine clinically significant agreement between the 2 methods. The Bland-Altman plots were used to determine whether these 2 methods agree sufficiently to be used interchangeably. Statistical significance was accepted at P ⩽ 0.05. RESULTS: Obtaining 2-dimensional images of kidney parenchyma and Doppler-derived measurements using TEE in children is feasible. There was statistically significant agreement between the 2 methods for all measurements. The CCC between the 2 imaging techniques was 0.91 for the pulsatility index and 0.66 for the resistive index. These coefficients were sensitive to outliers. When the highest and lowest data points were removed from the analysis, the CCC between the 2 imaging techniques was 0.62 for the pulsatility index and 0.50 for the resistive index. The 95% confidence interval (CI) for pulsatility index was 0.35 to 0.98 and for resistive index was 0.21 to 0.89. The Bland-Altman plots indicate good agreement between the 2 methods; for the pulsatility index, the limits of agreement were −0.80 to 0.53. The correlation of the size of the measurement and the mean difference in methods (−0.14; 95% CI = −0.28, 0.01) was not statistically significant (r = 0.31, P = 0.17). For the resistive index, the limits of agreement were −0.22 to 0.12. The correlation of the size of the measurement and the mean difference in methods (−0.05; 95% CI = −0.09, −0.01) was not statistically significant (r = 0.10, P = 0.65). CONCLUSION: This study confirms the feasibility of obtaining 2-dimensional images of kidney parenchyma and Doppler-derived measurements using TEE in children. Angle-independent TEE Doppler-derived indices show significant concordance with those derived by TAU. Further studies are required to assess whether this correlation holds true in the presence of renal pathology. This technique has the potential to help modulate intraoperative interventions based on their impact on renal variables and may prove helpful in the perioperative period for children at risk of acute kidney injury.

Cardiac arrest because of unrecognized delayed dilated cardiomyopathy in a child with severe burn injury.

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Application of mid-frequency ventilation in an animal model of lung injury: a pilot study.

BACKGROUND: Mid-frequency ventilation (MFV) is a mode of pressure control ventilation based on an optimal targeting scheme that maximizes alveolar ventilation and minimizes tidal volume (VT). This study was designed to compare the effects of conventional mechanical ventilation using a lung-protective strategy with MFV in a porcine model of lung injury. Our hypothesis was that MFV can maximize ventilation at higher frequencies without adverse consequences. We compared ventilation and hemodynamic outcomes between conventional ventilation and MFV. METHODS: This was a prospective study of 6 live Yorkshire pigs (10 ± 0.5 kg). The animals were subjected to lung injury induced by saline lavage and injurious conventional mechanical ventilation. Baseline conventional pressure control continuous mandatory ventilation was applied with VT = 6 mL/kg and PEEP determined using a decremental PEEP trial. A manual decision support algorithm was used to implement MFV using the same conventional ventilator. We measured PaCO2, PaO2, end-tidal carbon dioxide, cardiac output, arterial and venous blood oxygen saturation, pulmonary and systemic vascular pressures, and lactic acid. RESULTS: The MFV algorithm produced the same minute ventilation as conventional ventilation but with lower VT (−1 ± 0.7 mL/kg) and higher frequency (32.1 ± 6.8 vs 55.7 ± 15.8 breaths/min, P < .002). There were no differences between conventional ventilation and MFV for mean airway pressures (16.1 ± 1.3 vs 16.4 ± 2 cm H2O, P = .75) even when auto-PEEP was higher (0.6 ± 0.9 vs 2.4 ± 1.1 cm H2O, P = .02). There were no significant differences in any hemodynamic measurements, although heart rate was higher during MFV. CONCLUSIONS: In this pilot study, we demonstrate that MFV allows the use of higher breathing frequencies and lower VT than conventional ventilation to maximize alveolar ventilation. We describe the ventilatory or hemodynamic effects of MFV. We also demonstrate that the application of a decision support algorithm to manage MFV is feasible.

Rationalising the use of cardiac catheterisation before Glenn completion

Previous studies have shown that cardiac MRI can be used to evaluate the suitability for infants to undergo the Glenn operation after having undergone the Norwood procedure. We sought to analyse our institutional data retrospectively to identify whether such a policy would be advisable in the current era. We reviewed patients who underwent the Norwood procedure between 1 January, 2006 and 1 January, 2016. All patients undergoing evaluation for the Glenn procedure received clinical evaluation, echocardiography, and cardiac catheterisation. A total of 179 patients were identified; 154 patients (86%) survived to undergo cardiac catheterisation as part of evaluation for the Glenn, and all who were evaluated did not eventually receive the Glenn. Using said algorithm, if cardiac MRI or CT were to be used to rationalise the use of catheterisation, 26 of 154 patients would have required catheterisation after cross-sectional imaging identified vascular obstruction; 83 of 154 patients would have received cross-sectional imaging only; and 45 of 154 would have had catheterisation only. All cases that required intervention, excluding aortopulmonary collaterals, and all cases that were not suitable to progress would have been correctly identified using clinical and echocardiographic criteria in addition to cardiac cross-sectional imaging to rationalise the use of catheterisation. Thus, in cases with acceptable clinical, echocardiographic, and angiographic findings, the additional haemodynamic information from catheterisation is rarely of use for decision-making, and interventions can largely be predicted by angiographic imaging modalities.

Consensus Statement by the Congenital Cardiac Anesthesia Society: Milestones for the Pediatric Cardiac Anesthesia Fellowship

Pediatric cardiac anesthesiology has evolved as a subspecialty of both pediatric and cardiac anesthesiology and is devoted to caring for individuals with congenital heart disease ranging in age from neonates to adults. Training in pediatric cardiac anesthesia is a second-year fellowship with variability in both training duration and content and is not accredited by the Accreditation Council on Graduate Medical Education. Consequently, in this article and based on the Accreditation Council on Graduate Medical Education Milestones Model, an expert panel of the Congenital Cardiac Anesthesia Society, a section of the Society of Pediatric Anesthesiology, defines 18 milestones as competency-based developmental outcomes for training in the pediatric cardiac anesthesia fellowship.