Biomedical subjects
J D Tobias
Publications and source records attributed to J D Tobias.
Anesthetic implications of the grey platelet syndrome.
PURPOSE: To describe the obstetrical anesthetic care provided to two sisters with a rare qualitative platelet disorder, the grey platelet syndrome (GPS). CLINICAL FEATURES: Both patients manifested thrombocytopenia prior to delivery without previous history of a bleeding diathesis or other abnormal laboratory tests of coagulation function. The first required emergency Cesarean section due to fetal bradycardia. Due to the thrombocytopenia and the emergency nature of the procedure, general anesthesia was used. During the C-section, 1.5-2 litres of old blood was noted in the abdominal cavity which was attributed to an old splenic capsular tear of unknown etiology. Work-up for the thrombocytopenia revealed large platelets on the peripheral smear with abnormal aggregation on platelet function studies. Electron microscopy of the platelets revealed absent alpha granules, diagnostic of GPS. The second patient, the sister of patient #1, presented in a similar fashion. However, at presentation, the platelet count was 112,000 x m(-3) and spinal anesthesia was provided without complication for Cesarean delivery. The same patient presented for a second delivery during which fetal bradycardia necessitated emergency C-section under general anesthesia. Despite administration of six units of platelets, blood loss was 5,200 mL. Her postpartum course was uncomplicated and she and the infant were discharged home on postoperative day #4. CONCLUSION: The primary concerns for the anesthesiologist looking after patients with qualitative platelet defects are related to defective coagulation which influences the need for perioperative replacement of blood products and limits the use of regional anesthesia.
Weak analgesics and nonsteroidal anti-inflammatory agents in the management of children with acute pain.
The PSIs include acetaminophen, NSAIDs, and salicylates. They can be used alone for the treatment of mild pain or as an adjunct to opioid analgesia. In children, most experience is with acetaminophen and ibuprofen. For the treatment of mild to moderate pain, these agents can be administered as needed or at fixed intervals. The latter dosing scheme may provide a more consistent serum level, thereby improving analgesia. The major advantages of acetaminophen are its availability as a suppository for PR administration and its lack of effects on renal and GI function, adverse effects that may be seen with the NSAIDs. Many of the effects on platelet functioning, RBF, and the GI tract may be eliminated with the introduction of NSAIDs that selectively inhibit COX II without effects on COX I, the enzyme present in the GI tract, renal system, and platelets. Future evaluations with these agents in the pediatric population are needed. For more severe pain, the NSAID salicylate or acetaminophen can be combined with a weak opioid, such as codeine, oxycodone, or hydrocodone. When using oral analgesics, factors that may interfere with effective analgesia include a child's refusal to take the medication, ineffective doses and dosing regimens, decreased bioavailability following PO administration, inability to tolerate PO medications because of nausea or vomiting, altered GI motility, and a delayed onset caused by slow absorption. With such caveats in mind, the PO route provides an effective and cost-effective means for many patients. It should be considered as the primary route for pediatric patients in the treatment of mild to moderate pain, even in the hospital setting.
Central hyperventilation related to administration of topiramate.
Topiramate is a recently released antiepileptic agent used in the treatment of patients with refractory seizure disorders. In addition to its antiepileptogenic activities, it results in inhibition of carbonic anhydrase isoenzymes II and IV, which are present in the central nervous system. A 15-year-old female who presented with hyperpnea and primary respiratory alkalosis is reported. Other possible etiologies of the central hyperventilation syndrome were excluded. The problem resolved within 24 hours after discontinuing topiramate.
Noninvasive ventilation using bilevel positive airway pressure to treat impending respiratory failure in the postanesthesia care unit.
The author presents the use of noninvasive positive pressure ventilation using bilevel positive airway pressure (BiPAP) to treat respiratory insufficiency and hypoxemia in three patients in the postanesthesia care unit. BiPAP improved respiratory function with a decreased respiratory rate, decreased PaCO2, and improved oxygenation in the three patients. The applications of these techniques and equipment required are reviewed.
Spinal anaesthesia in infants and children.
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Applications of intrathecal catheters in children.
Access to the intrathecal space may be required for sampling of cerebrospinal fluid for diagnostic purposes, for the administration of pharmacological agents, or for cerebrospinal fluid (CSF) drainage to lower intracranial pressure. The current report details five children in whom a percutaneously placed lumbar intrathecal catheter was used: (i) to provide intraoperative surgical anaesthesia instead of general anaesthesia (ii); to deliver intrathecal fentanyl to provide postoperative analgesia (iii); to provide chronic pain control during the terminal stages of metastatic malignancy; (iv) to allow repeated doses of intrathecal chemotherapy; and (v) to allow CSF drainage and prevent CSF leakage following frontal encephalocele repair. The indications and applications of intrathecal catheters in the paediatric aged patient are reviewed.
Fenoldopam for controlled hypotension during spinal fusion in children and adolescents.
Fenoldopam is a dopamine1 agonist whose pharmacological effects include vasodilation of the vascular beds of the kidney, mesentery, skeletal muscle, and coronary systems, resulting in a decrease in systemic vascular resistance and mean arterial pressure. The current retrospective review outlines the use of fenoldopam for controlled hypotension during anterior or posterior spinal fusion in 10 children and adolescents, aged 8-14 years and weighing 22-61 kg. Fenoldopam was infused at a starting dose of 0.3-0.5 microg.kg-1. min-1 and increased incrementally to achieve a mean arterial pressure (MAP) of 50-65 mmHg. The desired MAP was achieved in 4-11 min (7+/-2.5 min). The fenoldopam infusion was administered for 135-225 min (160+/-25 min) in doses ranging from 0.2 to 2.5 microg. kg-1.min-1. The mean fenoldopam infusion rate for the 10 cases varied from 0.5 to 1.4 microg.kg-1.min-1 (1.0+/-0.3 microg.kg-1. min-1). No excessive hypotension or clinically significant adverse effects were noted. Statistically significant, but clinically insignificant, increases in heart rate and decreases in PaO2 were noted during the fenoldopam infusion. The baseline heart rate increased from 87+/-13 b.min-1 to a maximum of 114+/-16 b.min-1 (P < 0.0001) during the fenoldopam infusion. In the six patients undergoing posterior spinal fusion, the baseline PaO2 decreased from 232+/-7 mmHg to a low of 199+/-11 mmHg (P=0.0004) during the fenoldopam infusion. Fenoldopam can be used to provide controlled hypotension during spinal surgery in children and adolescents. Future studies, with direct comparison to other commonly used agents, are needed to better define its advantages and disadvantages as well as its effects on estimated blood loss.
Continuous pH and Pco2 monitoring during respiratory failure in children with the Paratrend 7 inserted into the peripheral venous system.
CONTEXT: The Paratrend monitor provides continuous arterial blood gas monitoring after insertion through a >/=20-gauge arterial cannula. OBJECTIVE: To determine the correlation of arterial blood gas values and the Paratrend monitor placed through a peripheral intravenous catheter. DESIGN: Prospective, open-label evaluation. SETTING: University-based pediatric intensive care unit. PATIENTS: Infants and children with respiratory failure and arterial access. RESULTS: The cohort included 23 infants and children. A total of 100 sample sets (Paratrend/ABG Pco(2) and pH values) were collected. The absolute difference between the arterial and Paratrend Pco(2) was 2. 9 +/- 1.8 mm Hg (range 0 to 9 mm Hg). Linear regression analysis of Paratrend Pco(2) versus arterial Pco(2) resulted in r = 0.97 and r(2) = 0.9479 (P <.001). Bland-Altman analysis of Pco(2) values demonstrated a bias +/- precision of -2.1 +/- 2.7 mm Hg. The absolute difference between arterial and Paratrend pH was 0.04 +/- 0. 02 units (range 0 to 0.15 units). Linear regression analysis of Paratrend pH versus arterial pH resulted in r = 0.83 and r(2) = 0. 7016 (P <.0001). Bland-Altman analysis of pH values revealed a bias +/- precision of 0.03 +/- 0.03 units. CONCLUSIONS: Inserted through a peripheral intravenous cannula, the Paratrend monitor can be used to provide an accurate estimation of arterial blood gas values in children with respiratory failure.
Pediatric regional anesthesia: beyond the caudal.
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Rapacuronium administration to two children with Duchenne's muscular dystrophy.
Children with Duchenne's muscular dystrophy should not be exposed to succinylcholine because of the risk of hyperkalemic cardiac arrest and rhabdomyolysis. This report describes the response to rapacuronium bromide in two patients with Duchenne's muscular dystrophy. Both patients had a recovery index 2 times longer than that reported in children with normal neuromuscular function.
Prospective study of airway management of children requiring endotracheal intubation before admission to a pediatric intensive care unit.
OBJECTIVE: To prospectively identify complications related to airway management in children before pediatric intensive care unit (ICU) admission. DESIGN: A descriptive, prospective study covering an 18-month period. A survey was completed at the time of admission to obtain demographic data, reason for endotracheal (ET) intubation, medications administered, location of and personnel responsible for ET intubation, and major/minor variances associated with airway management. Major variances were defined as technical problems resulting in a significant risk for airway trauma and increased morbidity. Minor variances were problems that should be avoided, but which do not significantly increase the immediate risk to the patient. Additional information obtained included whether a chest radiograph (CXR) was obtained and if postextubation problems occurred, such as stridor requiring treatment or reintubation. SETTING: Community hospitals, emergency rooms, children's hospital emergency rooms PATIENTS: All children < or =18 yrs of age receiving ET intubation before admission to the pediatric ICU, except those in cardiovascular arrest. MEASUREMENTS AND MAIN RESULTS: Data were collected on 250 consecutive patients. Major or minor variances were noted in 135 (54%) patients and in 66% of patients < or =1 yr of age (p = .02865; odds ratio, 2.0). Twenty-six percent of patients < or =1 yr of age received an anticholinergic agent before ET intubation compared with 40% of older patients (p = .04343; odds ratio, 0.504). Eleven patients received a neuromuscular blocking agent (NMBA) without a sedative/analgesic agent. Major variances occurred in 54% of patients who did not receive a NMBA and in 27% of patients who received a NMBA (p = .00002; odds ratio, 0.307). Forty-one patients (16%) were intubated with an inappropriately sized ET tube. Postintubation CXRs were obtained in 65% of patients managed outside of a children's hospital and in 93% of patients in a children's hospital emergency room (p < .00001; odds ratio, 7.199). Variances detectable by CXR went unrecognized in 40% of patients, despite obtaining a CXR. CONCLUSIONS: Emergency airway management in children can be fraught with problems. Most variances could be avoided by improved education regarding appropriate ET tube size, appropriate medication use, and improved training for evaluation of ET tube placement.
Tolerance, withdrawal, and physical dependency after long-term sedation and analgesia of children in the pediatric intensive care unit.
OBJECTIVE: To describe the consequences of the prolonged administration of sedative and analgesic agents to the pediatric intensive care unit (PICU) patient. The problems to be investigated include tolerance, physical dependency, and withdrawal. DATA SOURCES: A MEDLINE search was performed of literature published in the English language. Cross-reference searches were performed using the following terms: sedation, analgesia with PICU, children, physical dependency, withdrawal; tolerance with sedative, analgesics, benzodiazepines, opioids, inhalational anesthetic agents, nitrous oxide, ketamine, barbiturates, propofol, pentobarbital, phenobarbital. STUDY SELECTION: Studies dealing with the problems of tolerance, physical dependency, and withdrawal in children in the PICU population were selected. DATA EXTRACTION: All of the above-mentioned studies were reviewed in the current manuscript. DATA SYNTHESIS: A case by case review is presented, outlining the reported problems of tolerance, physical dependency, and withdrawal after the use of sedative/analgesic agents in the PICU population. This is followed up by a review of the literature discussing current treatment options for these problems. CONCLUSIONS: Tolerance, physical dependency, and withdrawal can occur after the prolonged administration of any agent used for sedation and analgesia in the PICU population. Important components in the care of such patients include careful observation to identify the occurrence of withdrawal signs and symptoms. Treatment options after prolonged administration of sedative/analgesic agents include slowly tapering the intravenous administration of these agents or, depending on the drug, switching to subcutaneous or oral administration.
Endocarditis attributable to group A beta-hemolytic streptococcus after uncomplicated varicella in a vaccinated child.
Varicella is generally a benign, self-limited childhood illness; however, severe, life-threatening complications do occur. A live, attenuated vaccine exists to prevent this illness, but controversy remains concerning the need to vaccinate children for what is generally a benign, self-limited disease, although more states are currently recommending this vaccine. We report a previously healthy 3-year-old who developed varicella 6 months after vaccination with no apparent skin superinfections, who subsequently developed group A beta-hemolytic streptococcus (GABHS) bacteremia resulting in endocarditis of a normal heart valve. We are unaware of previous reports of endocarditis related to GABHS after varicella. After developing a harsh, diastolic murmur that led to an echocardiogram, aortic valve endocarditis was diagnosed. A 6-week course of intravenous penicillin G was administered. Two weeks after the initiation of therapy, the diastolic murmur was harsher, and echocardiography revealed a large vegetation on the posterior leaflet of the aortic valve, with severe aortic insufficiency and a dilated left ventricle. The patient subsequently developed congestive heart failure requiring readmission and aggressive management. One month after the initial echocardiogram, a repeat examination revealed worsening aortic regurgitation and mitral regurgitation. The patient received an additional 4 weeks of intravenous penicillin and gentamicin followed by aortic valve replacement using the Ross procedure. Our patient, the first reported case of bacteremia and endocarditis from GABHS after varicella, illustrates the need for the health care practitioner to consider both common and life-threatening complications in patients with varicella. While cellulitis, encephalitis, and septic arthritis may be readily apparent on physical examination and commonly recognized complications of varicella, the possibility of bacteremia without an obvious skin superinfection should also be entertained. The case we report is unique in that the patient had normal immune function, had been previously vaccinated, and developed a rare complication of varicella-endocarditis-in a structurally normal heart with a previously unreported pathogen. Although a child may have been vaccinated against varicella, the chance of contracting the virus still exists and parents should be informed of this risk. group A beta-hemolytic streptococcus, endocarditis, varicella, Varivax, complications of varicella.
Mivacurium administration in children with Duchenne muscular dystrophy.
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Initial experience with isradipine for the treatment of hypertension in children.
BACKGROUND: Isradipine is a calcium channel blocker of the dihydropyridine class. It has limited effects on myocardial contractility; is available in a powder-filled capsule and has a half-life of 6 to 8 hours. METHODS: Pharmacy records were reviewed to identify pediatric patients who had received isradipine. The following demographic data were obtained: age, weight, sex, underlying medical problems, and initial blood pressure values. Information concerning isradipine included the initial dose and its interval, subsequent dose escalations, blood pressure response to the medication, and duration of therapy. RESULTS: The study population comprised 12 patients, ranging in age from 10 days to 11 years. The etiology of the hypertension was renal in 9 cases and nonrenal in 3. Initial dosing with isradipine was 0.1 mg/kg/dose. Six patients had emergent hypertension, and their blood pressure had been controlled with intravenous nicardipine before oral isradipine. Six patients received initial therapy with oral isradipine. Isradipine was monotherapy in 7 patients and in combination with other agents in 5 patients. The dose of isradipine required for blood pressure control was 0.6 +/- 0.3 mg/kg/day (range, 0.3 to 1.2 mg/kg/day). Isradipine failed to provide effective blood pressure control in 2 patients. In 1 of these patients, isradipine was effective after peritoneal dialysis. CONCLUSIONS: Isradipine is an effective, orally administered agent for control of hypertension in children.
Caffeine in the treatment of apnea associated with respiratory syncytial virus infection in neonates and infants.
BACKGROUND: The xanthines have been shown to be effective in the treatment of apnea of prematurity. Limited reports are available in the literature concerning the use of these agents with apnea related to respiratory syncytial virus (RSV) infections. METHODS: A retrospective review was done to identify infants who received caffeine therapy for RSV-associated apnea. The number of apneic episodes during the 2 hours before the use of caffeine and the number of apneic episodes after the administration of caffeine were compared using a Wilcoxon nonparametric test. RESULTS: The 7 infants ranged in age from 14 to 64 days and in weight from 2.8 to 4.4 kg. The number of apneic episodes per hour for the 2 to 3 hours before the administration of caffeine ranged from 7 to 12, and the number of episodes during the 3 hours after the administration of the first dose of caffeine ranged from 0 to 2. The apneic episodes after caffeine responded to external stimulation. Apnea recurred in 3 infants, 18 to 24 hours after the first dose of caffeine. These infants received a second dose of caffeine (5 mg/kg). CONCLUSIONS: Caffeine should be considered in the treatment of apnea related to RSV infections in neonates and infants.
Antiphospholipid antibody syndrome manifested as a postoperative cerebrovascular event in a child.
Perioperative cerebrovascular events are exceedingly uncommon in pediatric patients. The etiology of such problems includes emboli from intracardiac thrombi, sickle cell disease, vascular anomalies, vasculitis affecting the cerebral vasculature, and prothrombotic states. We describe a 6-year-old boy who had right-sided hemiparesis on the second postoperative day after an uneventful patch angioplasty for renal artery stenosis. Workup revealed a possible hypercoagulable state due to an anticardiolipin antibody. The pathogenesis of the anticardiolipin antibody syndrome, its clinical manifestations, diagnostic criteria, and potential treatment strategies are reviewed.