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Biomedical subjects

S C Nicolson

Publications and source records attributed to S C Nicolson.

At least 19 recordsLinked to original sources
PubMed1995

Interrupted aortic arch. Impact of subaortic stenosis on management and outcome.

Interrupted aortic arch (IAA) is often related developmentally to subaortic obstruction (SAO). When severe, SAO must be addressed in surgical management of IAA. From 1990 to 1993, 25 neonates presented for initial surgical management of IAA complexes. Associated lesions were ventricular septal defect (VSD) with or without atrial septal defect (19 patients), truncus arteriosus (3 patients), tricuspid atresia with transposition of the great arteries (1 patient), aortic atresia with VSD (1 patient), and d-transposition of the great arteries with VSD (1 patient). Overall hospital mortality was 20% (five deaths). One death was related to sepsis and two to sudden hemodynamic decompensation (a 2-kg premature infant after arch repair and VSD closure and a neonate with IAA-truncus arteriosus after arch repair and truncus repair with aortic root replacement). Two deaths were related to low cardiac output in patients with severe subaortic narrowing (< 3 mm by two-dimensional echocardiography), which was not addressed surgically. Of 10 additional patients judged preoperatively to have severe SAO, 1 underwent resection of the infundibular septum together with VSD closure and arch reconstruction, and 9 underwent a modification of Norwood's operation with arch reconstruction and proximal pulmonary artery to aortic anastomosis (7 with systemic to pulmonary artery shunts and 2 with right ventricle to pulmonary artery outflow tract reconstruction). One patient died 2 months after surgery of staphylococcal sepsis. All 9 others were discharged well. Subaortic narrowing is a physiologically important element of IAA complexes. When SAO is severe, satisfactory initial palliation can be achieved by a modification of Norwood's operation.

Aorta, Thoracic↗
PubMed1995

Avoidance of subaortic obstruction in staged management of single ventricle.

BACKGROUND: Subaortic obstruction is a frequent accompaniment of single-ventricle anatomy. Most often, the aorta arises from an outflow chamber that is connected to the single ventricle by a bulboventricular foramen or ventricular septal defect. This connection may be restrictive of flow at birth, or may become obstructive after surgical procedures that reduce the volume work of the ventricle. Subaortic obstruction is recognized as a risk factor for reconstructive surgical procedures for single ventricle. METHODS: To prevent the consequences of subaortic obstruction, we have routinely amalgamated the proximal main pulmonary artery with the ascending aorta and arch early in the management of these patients. From September 1990 through September 1994, 29 neonates and infants with single ventricle and established or potential subaortic obstruction underwent staged reconstructive surgical procedures. The initial operation in the newborn period was a Norwood procedure (18 patients) or a pulmonary artery band (5 patients). All survivors underwent a hemi-Fontan procedure at approximately 6 months. RESULTS: Eighteen patients have undergone a completion Fontan operation with no deaths. Five await completion Fontan. None has subaortic obstruction, and none has pulmonary valve insufficiency that is graded more than mild. CONCLUSIONS: Early association of the proximal main pulmonary artery with the ascending aorta appears to obviate the risks and complications associated with subaortic obstruction in patients with single ventricle.

Cardiac Surgical Procedures↗
PubMed1995

Results of Norwood's operation for lesions other than hypoplastic left heart syndrome.

Norwood's operation provides satisfactory palliation for neonates with hypoplastic left heart syndrome. The dominant physiologic features of hypoplastic left heart syndrome, ductal dependency of the systemic circulation and parallel pulmonary and systemic circulations, are shared by a multitude of other less common congenital heart malformations. Theoretically, these should be equally amenable to palliation by Norwood's operation. Between January 1990 and June 1994, 60 neonates with malformations other than hypoplastic left heart syndrome underwent initial surgical palliation by Norwood's procedure. Diagnoses included single left ventricle with levo-transposition of the great arteries (12); critical aortic stenosis (8); complex double-outlet right ventricle (8); interrupted aortic arch with ventricular septal defect and subaortic stenosis (7); ventricular septal defect, subaortic stenosis, and coarctation of the aorta (7); aortic atresia with large ventricular septal defect (6); tricuspid atresia with transposition of the great arteries (6); heterotaxy syndrome with subaortic obstruction (3); and other (3). There were 10 hospital deaths and 50 survivors (83% survival). After the introduction of inspired carbon dioxide therapy into the postoperative management protocol (1991), 42 of 47 patients survived (89% survival). Mortality was independent of diagnosis and essentially the same as that for hypoplastic left heart syndrome. With minor technical modifications, Norwood's operation provides satisfactory initial palliation for a wide variety of malformations characterized by ductal dependency of the systemic circulation in anticipation of either a Fontan procedure or a biventricular repair.

Aorta, Thoracic↗
PubMed1995

Cerebral oxygenation during pediatric cardiac surgery using deep hypothermic circulatory arrest.

BACKGROUND: Deep hypothermic circulatory arrest is a widely used technique in pediatric cardiac surgery that carries a risk of neurologic injury. Previous work in neonates identified distinct changes in cerebral oxygenation during surgery. This study sought to determine whether the intraoperative changes in cerebral oxygenation vary between neonates, infants, and children and whether the oxygenation changes are associated with postoperative cerebral dysfunction. METHODS: The study included eight neonates, ten infants, and eight children without preexisting neurologic disease. Cerebrovascular hemoglobin oxygen saturation (SCO2), an index of brain oxygenation, was monitored intraoperatively by near-infrared spectroscopy. Body temperature was reduced to 15 degrees C during cardiopulmonary bypass (CPB) before commencing circulatory arrest. Postoperative neurologic status was judged as normal or abnormal (seizures, stroke, coma). RESULTS: Relative to preoperative levels, the age groups experienced similar changes in SCO2 during surgery: SCO2 increased 30 +/- 4% during deep hypothermic CPB, it decreased 62 +/- 5% by the end of arrest, and it increased 20 +/- 5% during CPB recirculation (all P < 0.001); after rewarming and removal of CPB, SCO2 returned to preoperative levels. During arrest, the half-life of SCO2 was 9 +/- 1 min in neonates, 6 +/- 1 min in infants, and 4 +/- 1 min in children (P < 0.001). Postoperative neurologic status was abnormal in three (12%) patients. The SCO2 increase during deep hypothermic CPB was less in these patients than in the remaining study population (3 +/- 2% versus 33 +/- 4%, P < 0.001). There were no other significant SCO2 differences between outcome groups. CONCLUSIONS: Brain oxygenation changed at distinct points during surgery in all ages, reflecting fundamental cerebral responses to hypothermic CPB, ischemia, and reperfusion. However, the changes in SCO2 half-life with age reflect developmental differences in the rate of cerebral oxygen utilization during arrest, consistent with experimental work in animals. Certain intraoperative cerebral oxygenation patterns may be associated with postoperative cerebral dysfunction and require further study.

Aging↗
PubMed1994

A single dose of morphine sulfate increases the incidence of vomiting after outpatient inguinal surgery in children.

BACKGROUND: In children, opioids are valuable both for their analgesic properties and for their salutary effect on emergence delirium. Although intraoperative administration of opioids is often cited as the cause of postoperative emesis, few data quantitating the magnitude of this effect exist. METHODS: Patients undergoing inguinal surgery as outpatients were randomly assigned to one of two groups. One group received a single intravenous dose of morphine 0.1 mg/kg (morphine group), and the other (control) group had the identical anesthetic but instead received saline. Intravenous ketorolac was administered in response to verbal complaints of pain or a Children's Hospital of Eastern Ontario Pain Score greater than 9 on two successive evaluations performed at 5-min intervals. The authors compared the incidence of postoperative emesis and emergence, behavior, and pain scores between the two groups. RESULTS: Patients in the morphine group (n = 48) were 5.6 +/- 2.8 yr old and weighed 20.8 +/- 7.8 kg, and those in the control group (n = 49) were 4.5 +/- 2.9 yr old and weighed 18.9 +/- 9.2 kg. More patients in the morphine group were cooperative and deeply asleep both on arrival and through the first 30 min of their stay in the postanesthesia care unit (PACU) (P < 0.05). Sixty-three percent of the children in the control group received ketorolac in the PACU compared with 20% of the morphine group (P < 0.01). The incidence of emesis for the 24 h after arrival in the PACU was 56% for those who received morphine compared with 25% in the control group (P < 0.01). CONCLUSIONS: For children undergoing inguinal surgery, the administration of a single dose of intravenous morphine after the induction of anesthesia smooths emergence from anesthesia as assessed by improved cooperation and sedation in the PACU, decreases the need for postoperative analgesics, but increases the incidence of vomiting in the first 24 h after surgery.

Age Factors↗
PubMed1994

Feed the babies.

Explore the source record for details and available documents.

Anesthesia↗
PubMed1994

The metabolic effects of surface cooling neonates prior to cardiac surgery.

Neonates undergoing cardiac surgery at The Children's Hospital of Philadelphia frequently developed metabolic acidemia as they passively cooled prior to the start of cardiopulmonary bypass. This study was performed in an attempt to identify the mechanism for this acidemia. After receiving an initial dose of fentanyl (10 micrograms/kg) and pancuronium, 22 neonates were randomly assigned to maintain normothermia by active warming (Group I), or to permit passive cooling (Group II) before surgery. Arterial blood samples were obtained prior to, and at 10 and 45 min after entering the operating room for the analysis of pH, gas tensions, lactate, pyruvate, plasma free fatty acids, acetoacetate, beta-hydroxybutyrate, total CO2, and glucose concentrations. In the last 11 patients studied, the observation period was extended to 75 min at which time another arterial blood sample was obtained. There was a steady decrease in heart rate as the Group II patients cooled; however, arterial blood pressure did not change in either group. There were no changes in blood values measured in Group I neonates. In the Group II patients, there was a progressive decline in calculated base excess, total CO2, and an increase in serum lactate as the patients cooled. The metabolic acidemia that develops in neonates represents lactate accumulation as a consequence of surface cooling prior to surgery and the institution of cardiopulmonary bypass. Whether lactate accumulates as a result of anaerobic metabolism in underperfused tissue beds or reduced hepatic clearance could not be distinguished in this study. Since neither clinically significant hemodynamic changes nor differences in outcome were found between the two groups, the authors believe this mild lactic acidemia is inconsequential and does not require therapy.

Acidosis↗
PubMed1993

Propofol anesthesia reduces emesis and airway obstruction in pediatric outpatients.

This study was an authors comparison of the effects of and recovery from anesthesia in healthy, premedicated pediatric outpatients who received either inhaled anesthetics (group 1) or propofol (group 2). Group 1 (n = 68) averaged 3.8 +/- 0.2 yr and weighed 17.7 +/- 0.8 kg, whereas group 2 (n = 75) averaged 3.3 +/- 0.2 yr and weighed 16.3 +/- 0.6 kg. The incidence of vomiting in the Postanesthetic Care Unit (PACU) and from discharge to the first postoperative morning was lower in the group receiving propofol (0% and 18%) than in the group receiving volatile agents (7% and 34%, P < 0.05). The incidence of airway obstruction during induction of anesthesia was higher (34% vs 10%, P < 0.01) in children receiving inhaled agent. Withdrawal of the extremity with propofol injection occurred in 14 (19%) patients. Arterial blood pressure was higher at loss of consciousness, laryngoscopy, and tracheal intubation in group 2 (P < 0.01). The length of time from the end of surgery to extubation of the trachea, recovery scores, and length of time spent in the PACU and the Day Surgery Unit were the same in the two groups. Pain scores obtained in the PACU were not different. The data indicate that propofol can be used safely to induce and maintain anesthesia in healthy pediatric outpatients. This coupled with the low incidence of vomiting and airway obstruction in the propofol group suggests distinct and compelling reasons to consider using the drug in this patient population.

Airway Obstruction↗
PubMed1993

Influence of sensor site location on pulse oximetry kinetics in children.

A pulse oximeter sensor is used to monitor changes in arterial hemoglobin oxygen saturation (SpO2) in anesthetized pediatric patients. The authors compared the kinetics of desaturation and resaturation measured by sensors placed over central (tongue, cheek) and peripheral (finger, toe) vascular beds in children with congenital heart disease. Desaturation time was defined as the time which elapsed between the onset of apnea and a 4% decrease in SpO2 from baseline. The desaturation times averaged 24 +/- 12 s, 56 +/- 34 s, and 58 +/- 28 s for the cheek, finger, and toe, respectively (n = 40; P < 0.0001 for cheek versus finger or toe). Resaturation time was defined as the interval between the resumption of ventilation and a 4% increase in SpO2 above the nadir. Resaturation times averaged 12 +/- 8 s for the cheek, 40 +/- 36 s for the finger, and 47 +/- 25 s for the toe (n = 40; P < 0.0001 for cheek versus finger or toe). A comparison of the kinetics at two central sensor sites, cheek and tongue, respectively, revealed no significant differences in desaturation times (20 +/- 10 s vs 21 +/- 9 s) or resaturation times (10 +/- 6 s vs 7 +/- 3 s) (n = 13). The authors conclude that both desaturation and resaturation are detected earlier by centrally placed sensors.

Biosensing Techniques↗
PubMed1993

Desmopressin does not decrease bleeding after cardiac operation in young children.

Young children undergoing complex cardiac operation lose more blood after cardiopulmonary bypass than do older patients. This study was designed to investigate the effect of desmopressin on blood loss during the first 24 hours after cardiac operation in children undergoing principally complex surgical procedures. The study consisted of a randomized, blinded comparison of 112 pediatric patients who received either desmopressin 0.3 microgram/kg or saline solution placebo after cardiopulmonary bypass. A coagulation profile including bleeding time, quantitation of von Willebrand factor, and qualitative analysis of the factor VII:von Willebrand factor complex was performed before, 30 minutes after, and 3 hours after the operation. Blood loss and blood replacement were recorded for the first 24 hours after the operation. The surgeon classified the technical difficulty of each procedure as simple or complex. Statistical analysis was performed with Student's unpaired t test and chi 2 analysis. Significance was defined as p < 0.05. Results are listed as mean +/- standard deviation. Data collection was completed for 95 patients. The mean age of all patients was 26 +/- 40 months, and the mean weight was 10 +/- 11 kg, with 84% undergoing complex procedures. There were no differences between the desmopressin and placebo groups with respect to age, weight, or surgical complexity. Twenty-four-hour blood loss and replacement between the desmopressin and placebo groups were not different (blood loss: desmopressin 30 +/- 33 ml/kg, placebo 35 +/- 36; blood replacement: desmopressin 65 +/- 43 ml/kg, placebo 64 +/- 46 ml/kg). Coagulation profiles between the desmopressin and placebo groups were not different at any time. We conclude that desmopressin does not reduce blood loss or blood replacement in young children after cardiopulmonary bypass for either simple or complex cardiac surgical procedures.

Adolescent↗
PubMed1992

Carbon dioxide prevents pulmonary overcirculation in hypoplastic left heart syndrome.

Circulatory and metabolic homeostasis in patients with hypoplastic left heart syndrome is dependent on a delicate balance between systemic and pulmonary blood flow. Hypocarbia can result in a marked decrease in pulmonary vascular resistance accompanied by pulmonary overcirculation, systemic hypotension, metabolic acidosis, and death. This report illustrates that early and precise control of the arterial carbon dioxide tension using inspired carbon dioxide can be effective in preventing or treating instability arising during management of a patient with hypoplastic left heart syndrome.

Acidosis, Respiratory↗
PubMed1992

The effect of administering or withholding dextrose in pre-bypass intravenous fluids on intraoperative blood glucose concentrations in infants undergoing hypothermic circulatory arrest.

Thirty-six fasted infants under 1 year of age who were scheduled for elective cardiac surgery using hypothermic bypass with circulatory arrest were randomized to receive a lactated Ringer's (LR) solution (group I) or a LR with 5% dextrose solution (group II) in the pre-bypass period. Marked increases in blood glucose concentrations were found following institution of bypass and circulatory arrest in the children in both groups. There was no correlation between the amount of dextrose infused in the pre-bypass period and the presence of hyperglycemia following institution of bypass. A single patient in group I was hypoglycemic (blood glucose less than 30 mg/dL) on the initial glucose determination and the blood glucose did not increase during the pre-bypass period. Elimination of dextrose from the parenteral fluids given before bypass will not eliminate hyperglycemia following institution of bypass; however, it may expose pediatric patients to the risks of hypoglycemia before bypass.

Blood Glucose↗
PubMed1992

Should children drink before discharge from day surgery?

The ability to drink clear liquids without vomiting after anesthesia and surgery is a commonly used criteria for discharge of pediatric day surgery patients. We hypothesized that the ability to drink as a prerequisite for discharge would not affect the frequency of vomiting, delay discharge, or increase the frequency of readmission of children for dehydration after day surgical procedures. We randomized 989 patients between the ages of 1 month and 18.0 yr to one of two groups. The 464 "mandatory drinkers" were required to demonstrate the ability to drink clear liquids without vomiting prior to discharge from the hospital, whereas 525 "elective drinkers" were allowed but not required to drink. Other than the discharge criteria, the patients were managed in an identical fashion; the minimum volume of intravenous fluids received by all patients was adequate to supply a calculated 8-h fluid deficit prior to discharge from the hospital. There were no differences between the two groups in the incidence of vomiting in the operating room, the postanesthesia care unit, or after discharge from the hospital. However, in the day surgery unit, only 14% of the elective drinkers vomited compared to 23% of the mandatory drinker group (P less than 0.001). The mandatory drinkers had a more prolonged stay in the day surgical unit, averaging 101 +/- 58 min (mean +/- SD) compared to 84 +/- 40 min for elective drinkers (P less than 0.001). No patient in either group required admission to the hospital for persistent vomiting on the day of surgery, and no patient required readmission for vomiting or dehydration after discharge from the day surgery unit.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Kinetics of cerebral deoxygenation during deep hypothermic circulatory arrest in neonates.

Brain injury associated with neonatal congenital heart operations performed during deep hypothermia and/or total circulatory arrest is often attributed to cerebral hypoxia. We studied the kinetic changes in cerebrovascular hemoglobin O2 saturation (HbO2%) and total hemoglobin concentration (Hbtotal) in 17 neonates undergoing cardiac surgery as they were cooled to 15 degrees C, underwent total circulatory arrest, and were rewarmed. HbO2% and Hbtotal in brain vasculature were monitored noninvasively by near-infrared spectroscopy. Neonates were cooled over 12 min and rewarmed over 15 min while being perfused using cardiopulmonary bypass (CPB). Total circulatory arrest lasted from 20 to 70 min. We found that HbO2% in brain vasculature increased during the initial 8 min of CPB as nasopharyngeal temperature decreased, and then remained constant until circulatory arrest. After the onset of circulatory arrest, cerebrovascular HbO2% decreased curvilinearly for 40 min; no further hemoglobin desaturation was observed from 40 to 70 min of arrest. The changes in cerebrovascular Hbtotal were quite different from those in HbO2%, as Hbtotal decreased during the initial minute of CPB and circulatory arrest and then remained constant until recirculation. Brain intravascular HbO2% and Hbtotal increased within 3 min after the onset of recirculation to prearrest levels, and during rewarming, HbO2% decreased to normothermic baseline values. The results demonstrate that cerebral oxygenation increased during CPB cooling; O2 was consumed by the neonatal brain during the initial 40 min of deep hypothermic circulatory arrest; and cerebral oxygenation was restored on recirculation. These observations may be important in identifying the etiologies of brain injury during neonatal congenital heart surgery.

Brain↗