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Biomedical subjects

Michael L Schmitz

Publications and source records attributed to Michael L Schmitz.

At least 19 recordsLinked to original sources
PubMed2007

Noninvasive cerebral oximeter as a surrogate for mixed venous saturation in children.

We evaluated the relationship between regional cerebral oxygen saturation (rSO(2)) measured by near-infrared spectroscopy (NIRS) cerebral oximeter with superior vena cava (SVC), inferior vena cava (IVC), right atrium (RA), and pulmonary artery (PA) saturation measured on room air and 100% inspired oxygen administered via a non-rebreather mask (NRB) in children. Twenty nine pediatric post-orthotopic heart transplant patients undergoing an annual myocardial biopsy were studied. We found a statistically significant correlation between rSO(2) and SVC saturations at room air and 100% inspired oxygen concentration via NRB (r = 0.67, p = 0.0002 on room air; r = 0.44, p = 0.02 on NRB), RA saturation (r = 0.56, p = 0.002; r = 0.56, p = 0.002), and PA saturation (r = 0.67, p < 0.001; r = 0.4, p = 0.03). A significant correlation also existed between rSO(2) and measured cardiac index (r = 0.45, p = 0.01) and hemoglobin levels (r = 0.41, p = 0.02). The concordance correlations were fair to moderate. Bias and precision of rSO(2) compared to PA saturations on room air were -0.8 and 13.9%, and they were 2.1 and 15.6% on NRB. A stepwise linear regression analysis showed that rSO(2) saturations were the best predictor of PA saturations on both room air (p = 0.0001) and NRB (p = 0.012). In children with biventricular anatomy, rSO(2) readings do correlate with mixed venous saturation.

Adolescent↗
PubMed2006

Successful anesthetic management of a child with an extensive facial hemangioma and high output cardiac failure for placement of a central venous catheter.

A two-and-a-half-year-old female with an extensive facial and lingual hemangioma, associated high output cardiac failure, and a history of difficult intubation presented for central venous catheter (CVC) placement for vincristine chemotherapy. Anesthetic management of this complex case is presented and the complicating medical conditions are discussed.

Anesthetics, Inhalation↗
PubMed2006

Cardiopulmonary bypass for adults with congenital heart disease: pitfalls for perfusionists.

The fixed incidence of congenital heart defects and improved survival have resulted in increasing numbers of adults with congenital heart disease (CHD) who have undergone complex repairs and/or palliations. Eventually, there will be more adults with CHD than children. They will require cardiac surgical interventions associated with progression of their CHD or for age-related disease, such as coronary revascularization. During bypass, anatomical shunts may exist within or without the heart. Left-to-right shunts can result in dramatically lower systemic blood flow than pump flow due to 'steal', while pulmonary edema ensues due to excessive pulmonary flow. Right-to-left shunts carry risks of massive air embolism and double or triple venous cannulation may be necessary. Cannulation of composite reconstructed aortas may be difficult, risking dissection or aortic obstruction, and double arterial cannulation may be indicated. Aberrant coronary arterial and venous anatomy may .preclude adequate myocardial preservation with common techniques and can be complicated by aortic insufficiency. Valves and conduits may exhibit failure. Conventional monitoring, such as central venous oximetry, may be misleading. Monitoring, such as serial lactate measurement, near-infrared spectroscopy and transcranial Doppler blood velocity, offer advantages for such patients. The perfusionist needs to be aware of such conditions as much congenital aberrancy may present unexpectedly during cardiac surgery.

Adult↗
PubMed2006

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.

Heart Transplantation↗
PubMed2005

Big help for small hearts.

The ACH Heart Center is a comprehensive, full-service resource for infants and children with congenital and acquired heart disease. UAMS physicians and nurses and ACH nurses and staff are here to care for these children both directly and by providing support to pediatricians and primary care physicians within Arkansas and the surrounding states.

Arkansas↗
PubMed2004

Venovenous extracorporeal membrane oxygenation for cyanotic congenital heart disease.

BACKGROUND: Severe, refractory hypoxemia complicating uncorrected cyanotic congenital heart disease is a potentially lethal condition, even when urgent surgical intervention is undertaken. When a viral pneumonia initiates hypoxemia, the likelihood of a satisfactory outcome is further reduced. We examined our policy of venovenous extracorporeal membrane oxygenation support through the hypoxic event and performing delayed surgery, if required, to separate from extracorporeal membrane oxygenation. METHODS: A single institution, retrospective review of an Institutional Review Board approved database was undertaken. Over a 6-year period, 18 instances were identified for 17 patients who became acutely hypoxemic from either inadequate pulmonary blood flow (8 instances) or a viral pneumonia (10 instances) complicating their cyanotic heart disease. Demographics, duration of venovenous extracorporeal membrane oxygenation and outcomes are reported. RESULTS: The length of venovenous extracorporeal membrane oxygenation ranged from 13.5 to 362.5 hours (mean 130 +/- 121 hours). During 10 supports, operations were performed to facilitate weaning from support. In 7 patients, extracorporeal support was weaned during this surgery. Follow-up was obtained in all patients over a period ranging from 4 months to 7 years (mean 39.0 +/- 23.0 months). There were two late deaths due to sepsis 1.4 and 2.5 months after extracorporeal support. CONCLUSIONS: Venovenous extracorporeal membrane oxygenation allows time for the recovery of acute hypoxic insult and resolution of some viral pneumonia processes. Palliative surgical procedures may be safely undertaken during extracorporeal support. Viral pneumonia is a risk for prolonged support. Venovenous extracorporeal membrane oxygenation is useful in these high-risk patients.

Child, Preschool↗
PubMed2004

Expanding the donor pool: use of a donor heart having undergone recent cardiac surgery.

The current shortage of donor organs is a well-recognized global phenomenon. The goal of contemporary transplant practice is to optimize and expand the organ donor pool. Despite biologic and technologic advancements, the single most important limitation remains underutilization and non-recovery of potential organs. We report the use of a donor cardiac organ from a 5-year-old child who had undergone recent (<72 hours) closure of an atrial septal defect. The heart was harvested successfully and implanted with no apparent hemodynamic compromise.

Child, Preschool↗
PubMed2004

Analgesia following surgery in children with and without cognitive impairment.

Both children and adults with cognitive impairment (CI) have historically been excluded from research examining pain. This is unfortunate since patients with CI may be at higher risk for experiencing pain or having their pain undertreated due to the difficulty of pain assessment and communication. There are now several published reports about the general pain experience of both adult and pediatric patients with cognitive impairment. The purpose of this study was to compare the amount and type of pain medication administered in children with and without CI after surgery to ascertain if there were any differences in analgesic administration patterns between these two groups. One hundred and fifty-two children with borderline to profound CI and 138 non impaired (NI) children were recruited to participate. Analgesic administration data include type and amount of opioid, type of non-opioid medication, and prescribed discharge medications. Results of this study show that children with CI undergoing surgery received less opioid in the perioperative period than children without CI. However, children with CI received comparable amounts and types of analgesics in the postoperative period as children without CI.

Adolescent↗
PubMed2004

Optimizing cardioplegia strategy for donor hearts.

Variability in organ preservation strategy has thus far prevented meaningful analysis of clinical donor heart cardioplegia strategies. This paper describes our donor heart procurement protocol, techniques, and recovery team responsibilities. We present 21 patients receiving cardiac transplantation at our institution with an adopted cardioplegia protocol. The procurement team perfusionist ensures consistent attention to myocardial protection with standards that are similar to those applied to native hearts for all congenital heart surgeries.

Adolescent↗
PubMed2004

Management of continuous venous gas emboli during extracorporeal life support utilizing the Kolobow gas trap.

Extracorporeal life support (ECLS) with a roller pump system uses a closed cardiopulmonary bypass (CPB) circuit not equipped with a venous reservoir. Hence, gas emboli cannot escape the ECLS circuit, predisposing to clot formation, membrane failure and potential gas embolism. Rarely, some patients may develop a continuous release of gas into the venous circulation from multiple sources. Two pediatric ECLS cases are presented with continuous venous gas embolism. A 'gas trap' was devised by creating a column of fluid erected vertically on the venous line. This allowed gas to rise within the column, separating it from the ECLS circuit, thus, preventing gas from lodging in the membrane.

Advanced Cardiac Life Support↗
PubMed2003

Transpleural subclavian central venous catheter placement in a child with scoliosis discovered during a thoracotomy.

Placement of central venous catheters in dysmorphic children can be difficult because of distortion of normal anatomical landmarks. We present such a case of a 16 year-old child who had a central venous catheter inserted in the left subclavian vein. Although a conventional roentgenogram was consistent with correct placement, the catheter was found to traverse the pleural space before entering the subclavian vein.

Adolescent↗
PubMed2003

Hemodynamic troubleshooting for mechanical malfunction of the extracorporeal membrane oxygenation systems using the PPP triad of variables.

Prolonged usage of disposable extracorporeal membrane oxygenation (ECMO) circuitry increases the risk of mechanical complications due to breakdown or malposition of the circuit elements. Often, such complications are life threatening for the critically ill patient. Such problems need to be rapidly identified and corrected. Algorithms can be especially helpful in such acute, life-threatening situations. We have outlined an algorithm that uses the relationship between three hemodynamic variables that can be used to rapidly identify mechanical dysfunctions associated with use of the ECMO circuit. These hemodynamic variables are premembrane pressure, pump flow, and patient mean systemic arterial pressure (the PPP triad). These variables are interrelated as a change in one variable results in a change in another. Mechanical malfunction can eliminate this relationship. Changes in one variable only suggest mechanical impairment or failure of the ECMO system. When such a change is detected, a checklist can be rapidly reviewed that directs an immediate logical assessment of potential mechanical causes of hemodynamic compromise.

Algorithms↗
PubMed2003

Management of potential gas embolus during closure of an atrial septal defect in a three-year-old.

Gas embolism occurring in adult patients supported with cardiopulmonary bypass is usually associated with mechanical complications. Management of gas embolism is less often described for the pediatric or neonatal patient. Measures to counteract gas embolism must be undertaken immediately if a satisfactory outcome is to be achieved. Here, the management of a three-year-old female patient, who was undergoing repair of a secundum atrial septal defect when the aortic cannula became dislodged and air entered the aorta, is described. Immediate implementation of an air embolism protocol, including (among other maneuvers) removal of air from the circuit, retrograde cerebral perfusion via the superior vena cava, and induction of cerebral hypothermia, may have aided in an acceptable outcome.

Child, Preschool↗