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Biomedical subjects

D R Cook

Publications and source records attributed to D R Cook.

At least 109 records · Page 6Linked to original sources
PubMed1981

Muscle relaxants in infants and children.

In the first 2 years of life there is physical and biochemical maturation of the neuromuscular junction of man. With this maturation there is an increase in the neuromuscular reserve (margin of safety) of the infant and a change in the contractile properties of skeletal muscle. On a weight basis neonates and young infants are resistant to both depolarizing and non-depolarizing muscle relaxants; when dosage is calculated on the basis of surface area neonates and young infants are not resistant to succinylcholine, but appear sensitive to non-depolarizing relaxants. Variation in extracellular fluid volume probably explains these differences in apparent resistance. Data relating recovery of neuromuscular transmission to plasma or tissue bath concentrations of dTc are conflicting. Awareness of the clinical response of neonates and infants to muscle relaxants and awareness of the non-neuromuscular blocking properties of relaxants in infants and children permits the use of these anesthetic adjuncts in patients of any age.

Adolescent↗
PubMed1977

Intracranial pressure: monitoring and normalization therapy in children.

The clinical course of 42 children with intracranial pressure monitoring was reviewed. Intracranial hypertension was documented in a variety of diagnostic categories. Therapy was titrated to maintain a baseline intracranial pressure of less than 15 torr (mm Hg), and to decrease the frequency of spontaneous and reactive pressure waves. Ventricular drainage, controlled hyperventilation, intravenous glycerol osmotherapy, therapeutic hypothermia, and barbiturate loading were employed as needed to achieve those goals. Survival was significantly related to average and peak intracranial pressure levels and to the degree of serum hyperosmolality that developed during therapy.

Adolescent↗
PubMed1976

Pharmacokinetics of succinylcholine in infants, children, and adults.

The elimination of succinylcholine appears to follow first-order kinetics with a linear relationship between intensity of effect and logarithm of the dose. Determination of the time-course of neuromuscular blockade following succinylcholine in infants and children allowed us to compare the rate of recovery and elimination rate constant with those determined by others in adults. The rate of recovery was independent of dose for each age group. The rate of recovery was faster in children than in infants; the rate of recovery of infants was faster than that of adults. The elimination rate constant for infants was similar to that of children; for both the infants and children the rate constants appeared dissimilar from those of adults.

Adult↗
PubMed1976

Pharmacodynamics of tubocurarine in humans.

The pharmacodynamics of neuromuscular transmission, following blockade by a single i.v. dose of tubocurarine (dtc) in humans, were simulated from experimental serum dtc concentration versus time data and serum dtc concentration versus percentage recovery data. Good agreement was obtained between the simulated and experimental time course of recovery at five different therapeutic doses. The initial apparent volume of distribution (Vapp) of dtc was approximately the same as the serum volume and appeared to increase with the size of the dose. These results were consistent with the suggestion that a greater fraction of the dose of dtc was distributed in non-vascular spaces or bound to tissue at larger doses. A pharmacodynamic working model using an average Vapp of 2848 ml simulated times up to 40% recovery within 15-20% error for doses of dtc of 0.30 mg/kg or less.

Dose-Response Relationship, Drug↗
PubMed1976

Paediatric anaesthesia: pharmacological considerations.

The young infant differs from the adult in his quantitative responses to many anaesthetic drugs and adjuncts. In the neonate, the larger extracellular fluid volume and blood volume, the smaller muscle mass and fat stores, and presumable greater blood flow to the central organs, not only influence the distribution of drugs to their active site but also secondary redistribution. The neonatal hepatic anzyme systems responsible for the metabolism of drugs are incompletely developed or absent. Glomerular filtration, important for drug excretion, is inefficient by adult standards. The neonate has increased toxicity and sensitivity to a variety of sedative-hypnotics, narcotics, and local anaesthetics. On the other hand, the infant requires more suxamethonium (succinylcholine) and ketamine on a weight basis that does the adult. The response of some infants to non-depolarising muscle relaxants resembles that of the myasthenic patients. The rate of uptake of alveolar levels of inhalation anesthetics is more rapid in infants and children than in adults. In addition, the neonate requires more anaesthetic than the adult for a given surgical stimulus. Biotransformation of inhalation anaesthetics is limited in neonates. Awareness of these pharmacological differences and their probable explanations allows one to provide rational, safer anaesthesia to infants.

Anesthesia↗
PubMed1975

Neuromuscular blocking effects of succinylcholine in infants and children.

The neuromuscular blocking effects and recovery times following two doses of succinylcholine on a weight basis were evaluated in 16 infants and 16 children. Infants had less profound neuromuscular blockade than children at both 0.5 and 1.0 mg/kg doses. Succinylcholine, 1 mg/kg, in infants produced blockade equal to that produced by 0.5 mg/kg in children; at these equipotent doses there was no statistically significant difference between the times to recover to 10 and 90 per cent neuromuscular transmission in the two groups. However, the rate of recovery from 50 per cent neuromuscular transmission to 90 per cent neuromuscular transmission was 69.1 per cent/min in children, as opposed to 46.4 per cent/min in infants. When dosage was calculated on a surface area basis, there was a linear relationship for infants and children as a single group between the log dose and the times to recover to 50 and 90 per cent neuromuscular transmission. Similarly, there was a linear relationship between the log dose (mg/m2) and the maximum intensity of neuromuscular blockade.

Adult↗
PubMedDate not supplied

Continuous alfentanil infusion in pediatric patients undergoing general anesthesia for complete oral restoration.

STUDY OBJECTIVE: To study the safety and efficacy of continuous alfentanil infusions in children. DESIGN: Randomized open study. SETTING: Outpatient pediatric anesthesia at a university medical center. PATIENTS: Forty pediatric patients aged 2 to 12 years about to undergo anesthesia for complete oral restoration. INTERVENTIONS: Twenty patients were anesthetized with halothane and nitrous oxide (N2O), and 20 patients were anesthetized with N2O and a 100 micrograms/kg bolus of alfentanil followed by a continuous alfentanil infusion. MEASUREMENTS AND MAIN RESULTS: Hemodynamic measurements, emergence times, and postoperative side effects were measured. Hemodynamic stability was maintained in both groups. Although children emerged faster and were extubated earlier when anesthetized with alfentanil, they required longer times until they could be discharged from the outpatient anesthesia area. Children anesthetized with alfentanil had a higher occurrence of postoperative emesis compared with children anesthetized with halothane. These differences, however, were not statistically significant. CONCLUSIONS: Alfentanil appears to be a safe anesthetic. The reason for prolonged discharge time in the alfentanil-anesthetized patient is unclear, but it may be related to postoperative vomiting.

Alfentanil↗