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Biomedical subjects

J D Tobias

Publications and source records attributed to J D Tobias.

At least 19 recordsLinked to original sources

Thoracoscopy in the pediatric patient.

The pediatric applications of minimally invasive surgical procedures such as thoracoscopy continue to increase. Specific alterations in anesthetic management may be required during the perioperative care of these patients. This article reviews the anesthetic care of infants and children during thoracoscopy with emphasis on cardiopulmonary disturbances of the patient, techniques to isolate the operative and nonoperative lungs and provide one-lung ventilation to improve surgical visualization, cardiopulmonary alterations induced by the creation of the artificial pneumothorax or the absorption of CO2 by the plural surface, intraoperative management of one-lung ventilation, and the potential for and treatment of inadvertent CO2 embolism.

Anesthesia↗

Variations on one-lung ventilation.

One-lung ventilation is a commonly used technique to facilitate surgical visualization during thoracic surgical procedures. New devices for one-lung ventilation have been introduced into clinical practice over the recent years. One such device is the Arndt Endobronchial Blocker which is a bronchial blocker with a central lumen through which a wire with a looped end has been passed. The loop on the distal end is meant to be placed over a fiberoptic bronchoscope which is then used as a guide to facilitate bronchial placement of the balloon-tipped bronchial blocker. Another advantage of the Arndt device is the airway adaptor that contains ports for the anesthesia circuit, the bronchoscope, the bronchial blocker as well as attachment to the endotracheal tube. The port for the bronchial blocker can be tightened down so as to hold the blocker in place during the procedure. However, patient issues such as size or airway alterations such as the presence of a tracheostomy may make necessary certain alterations in airway management. I describe four cases and provide suggestions for minor alterations in airway management that may be used to provide successful options for one-lung anesthesia.

Adult↗

Tolerance during sedation in a pediatric ICU patient: effects on the BIS monitor.

The authors demonstrate the effects of tolerance as measured using the bispectral index (BIS) monitor. Over a 5-day period, there was a twofold increase in the dose of midazolam and a threefold increase in the dose of fentanyl required to provide the same level of sedation and the same BIS number in a 9 year old boy receiving sedation during mechanical ventilation.

Adjuvants, Anesthesia↗

A dual epidural catheter technique to provide analgesia following posterior spinal fusion for scoliosis in children and adolescents.

BACKGROUND: The authors report their experience with the use of a dual epidural catheter technique in controlling pain following long posterior spinal fusion and instrumentation for scoliosis in children and adolescents. METHODS: Following completion of the surgical procedure and prior to wound closure, the upper catheter was inserted with the tip directed cephalad to T1-4 while the tip of the lower catheter was positioned at the L1-4 level. As the surgical wound was being closed, the catheters were dosed with fentanyl and hydromorphone followed by a continuous infusion of ropivacaine plus hydromorphone. Postoperative pain was assessed every 2-4 h using a visual analogue score or an observational behavioural score (0=no pain, 10=worst imaginable pain). There were 14 patients ranging in age from 5-17 years (12.7 +/- 3.5) and in weight from 19-68 kg (44.3 +/- 17.5). The epidural catheters were left in place until the fifth postoperative day. RESULTS: The mean of the median pain score from each patient was 1.5 +/- 1.6, 1.6 +/- 1.5, 1.4 +/- 1.3, 1.1 +/- 1.1 and 0.9 +/- 0.9, respectively, on postoperative days 1 through 5. The mean of the maximum pain scores was 3.5 +/- 2.3 (range 0-7), 4 +/- 1.6 (range 2-6), 3.1 +/- 1.7 (range 1-6), 2.4 +/- 1.5 (range 0-4) and 2.2 +/- 1.4 (range 0-4), respectively, on postoperative days 1 through 5. CONCLUSION: No adverse effects related to epidural analgesia were noted.

Adolescent↗

Anaesthetic management and high frequency oscillatory ventilation.

In an effort to decrease morbidity and mortality, newer modes of mechanical ventilation have been introduced into the critical care arena. One such technique, high frequency oscillatory ventilation (HFOV) relies on respiratory rates greater than 150 b.min-1, small tidal volumes, and the maintenance of a constant distending pressure thereby limiting peak inflating pressure and potentially the incidence of barotrauma. Despite the frequent application of this technique in the ICU setting, there is limited information concerning its intraoperative use. We present three infants who represent the perioperative applications of HFOV: (i) elective preoperative use to minimize lung movement and interference with surgical exposure during thoracotomy and PDA ligation; (ii) intraoperative application when progressive alterations in respiratory compliance led to ineffective intraoperative ventilation/oxygenation; and (iii) anaesthetic care for a neonate already receiving HFOV. The techniques of HFOV and previous reports of perioperative use are reviewed.

Anesthesia↗

Noninvasive monitoring of carbon dioxide during mechanical ventilation in older children: end-tidal versus transcutaneous techniques.

UNLABELLED: We prospectively compared the accuracy of end-tidal CO(2) (ETCO(2)) and transcutaneous CO(2) (TCCO(2)) monitoring in older pediatric patients (4 yr or older) receiving mechanical ventilation for respiratory failure. ETCO(2) and TCCO(2) were simultaneously monitored and compared with arterial CO(2) (PaCO(2)) values when arterial blood gas analysis was performed. Eighty-two sample sets were compared. The ETCO(2) to PaCO(2) difference was 6.4 +/- 6.3 mm Hg, whereas the TCCO(2) to PaCO(2) difference was 2.6 +/- 2.0 mm Hg (P < 0.0001). The absolute difference of ETCO(2) and PaCO(2) was 5 or less in 47 of 82 measurements, whereas the absolute TCCO(2) to PaCO(2) difference was 5 or less in 76 of 82 measurements (P < 0.00001). Regression analysis of ETCO(2) and PaCO(2) values revealed a correlation coefficient of 0.5418 and an r value of 0.8745. Regression analysis of TCCO(2) and PaCO(2) values revealed a correlation coefficient of 1.0160 and an r value of 0.9693. Bland-Altman analysis revealed a bias of -5.68 with a precision of +/-6.93 when comparing ETCO(2) with PaCO(2) and a bias of 0.02 with a precision of +/-3.27 when comparing TCCO(2) and PaCO(2) (P < 0.00001). TCCO(2) monitoring provided an accurate estimation of PaCO(2) over a wide range of CO(2) values and was superior to ETCO(2) monitoring in older pediatric patients with respiratory failure. TCCO(2) monitoring may be considered as a useful adjunct to monitoring of ventilation in this patient population. IMPLICATIONS: The authors report on the accuracy of noninvasive, transcutaneous CO(2) monitoring during mechanical ventilation in children 4 yr or older. Application of this technique should be useful by decreasing the need for repeated, costly, and sometimes painful arterial blood gas analysis, and the continuity of assessment should facilitate proactive, rather than reactive, ventilator manipulations.

Adolescent↗

Venous air embolism during endoscopic strip craniectomy for repair of craniosynostosis in infants.

BACKGROUND: Various studies have reported an incidence of venous air embolism (VAE) as high as 82.6% during surgical procedures for craniosynostosis. There has been an increase in the use of minimally invasive, endoseopie surgical procedures, including applications for endoscopic strip craniectomy. The current study prospectively evaluated the incidence of VAF during endoscopic strip craniectomy. METHODS: Continuous, intraoperative monitoring for VAE was performed using precordial Doppler monitoring. A recording was made of the Doppler tones and later reviewed to verify its accuracy. RESULTS: The cohort for the study included 50 consecutive neonates and infants ranging in age from 3.5 to 36 weeks and ranging in weight from 3 to 9 kg. Surgical time varied from 31 to 95 min for a total of 2,701 mm of operating time, during which precordial Doppler tones were auscultated. In 46 patients, there was no evidence of VAE. In four patients, there was a single episode of VAE. Two of the episodes of VAE were grade I (change in Doppler tones), and two were grade H (change in Doppler tones and decrease in end-tidal carbon dioxide). No grade III (decrease in systolic blood pressure by 20% from baseline) VAF was noted. CONCLUSION: In addition to previously reported benefits of decreased blood loss, decreased surgical time, and improved postoperative recovery time, the authors noted a low incidence of VAF during endoscopic strip craniectomy in neonates and infants.

Craniosynostoses↗

Bupropion overdose in an adolescent.

Bupropion is a relatively new monocyclic antidepressant whose mechanism of action remains unknown. In addition to its use as an antidepressant, it has also been suggested to be effective in children with attention deficit hyperactive disorder and more recently as an aid in the cessation of cigarette smoking. The latter indication has resulted in an increase in its use and therefore an increased availability in households. To date, reports of overdoses in pediatric patients are limited. We report a 14-year-old boy who ingested 1.5 to 3 g of bupropion in a suicide attempt. Previous reports of bupropion ingestions and its management are discussed.

Adolescent↗

Rapacuronium administration to patients receiving phenytoin or carbamazepine.

Patients receiving anticonvulsants such as phenytoin or carbamazepine may be resistant to neuromuscular blocking agents. The authors report the response to rapacuronium bromide (1.5 mg/kg) in two adult patients; one receiving phenytoin and the other receiving carbamazepine. In both patients, there was a delay in achieving maximum blockade; 100% depression of the first twitch was never achieved in the patient receiving phenytoin. Recovery of neuromuscular function was rapid. In the patient receiving phenytoin and carbamazepine respectively, the clinical duration (time to return of T1% to 25% of baseline) was 5 and 9 minutes, the recovery index (T1 25%-75%) was 4 minutes and 3 minutes, and the time to return of T4/T1 to greater than 0.7 was 15 minutes and 18 minutes 40 seconds. As has been reported with other neuromuscular blocking agents of the aminosteroid class, the clinical duration and the recovery index of rapacuronium are shortened in patients receiving either phenytoin or carbamazepine.

Adult↗

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.

Adult↗

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.

Acute Disease↗

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.

Adolescent↗

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.

Adolescent↗