Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0029713 (immaturity)
 4,335 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The domestic pig is a useful model in certain areas of biomedical research. Effective use of this species is often encumbered by lack of reference values in conscious as well as anaesthetized animals. Anaesthesia itself influences physiological and biological variables; the anaesthetic technique often affects experimental results. The relationship between anaesthesia and haemodynamics is well characterized in man, but less established in pigs. We studied the effect of midazolam-fentanyl-isoflurane anaesthesia in six immature, male, domestic pigs (Norwegian landrace). Haemodynamic variables (heart rate, arterial systolic, mean, diastolic pressures, pulmonary systolic, mean, diastolic pressures, pulmonary capillary wedge pressure), tissue perfusion, lymph flow (thoracic duct) were recorded for 3 h in animals with open chest through midline sternotomy. Variables relevant to fluid balance, e.g. interstitial hydrostatic pressure (Pi), serum-colloid osmotic pressure (s-COP) and serum-albumin (s-albumin) and -protein (s-protein) concentrations were measured. With the chosen anaesthetic technique haemodynamic variables, including lymph flow, and laboratory variables remained constant during the study period. Most variables were similar to conditions in humans. In contrast to adult humans exposed to the same anaesthetic technique, these pigs had lower haemoglobin-, s-albumin- and s-protein concentrations. A finding which may reflect immaturity. Liver and lung perfusion decreased significantly during the study period whereas perfusion of the other organs studied remained constant. Lack of responses to defined noxious stimuli during the study period suggest adequate analgesia. We conclude that midazolam, fentanyl and isoflurane provide cardiovascular stability including normal microvascular fluid exchange, which are essential elements for securing the quality of results obtained during cardiovascular research in anaesthetized pigs.
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PMID:Midazolam-fentanyl-isoflurane anaesthesia is suitable for haemodynamic and fluid balance studies in pigs. 971 80

Physiologic changes influence the pharmacokinetics of drugs relevant to anesthesia in neonates and infants. The neonatal phase is the phase of life with the most rapid and dramatic changes of organ-functions responsible for pharmacokinetics of most anesthetics. Changes in body composition and the content of plasma proteins influence volume of distribution, the drug distribution to different compartments and the amount of free fraction in plasma. Due to the immaturity of hepatic microsomal enzyme systems there is a decreased metabolism particular of agents which undergo low hepatic extraction like Diazepam, Morphine or some local anesthetics. In the first year of life capacity of the enzymatic systems increases and also clearance increases. Until puberty the clearance of some drugs is greater than the adult level. There are also pharmacodynamic changes like modified sensitivity to some drugs like volatile anesthetics or neuromuscular blocking agents. In summary neonates and infants are a highly heterogenous group with large interindividual differences. Therefore the dosage of anesthetic agents must be individualized to achieve optimal pharmacodynamic effects without toxicity in this age group.
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PMID:[Pharmacokinetics in newborns and infants]. 1054 58

We examined the demographic, seizure history, personality, and intellectual variables in seizure surgery patients who underwent intraoperative language mapping to identify variables that may help predict inability to cooperate with intraoperative mapping. Of 26 patients who had intraoperative language testing during left hemisphere lobectomy, 9 were unable to cooperate with language mapping procedures. Mapping "failure" consisted of an inability to conform to task demands due to anxiety, inattention, immaturity, or confusion that necessitated changing from local to general endotracheal anesthesia. Patients who were unable to cooperate with intraoperative mapping had significantly lower IQs, lower educational attainment, and higher Depression scale scores on the Minnesota Multiphasic Personality Inventory (MMPI) relative to cooperative patients. There were no statistically significant differences between groups with respect to age, handedness, sex, age of onset of habitual seizures, seizure type, site of seizure focus, presence of a lesion, or previous psychiatric history.
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PMID:Predictors of Patient Inability to Cooperate during Intraoperative Language Mapping. 1260 63

We have already suggested that there is an active bimodal sphincteric mechanism in the human vesicoureteral junction (VUJ). This mechanism is affected by immaturity, hormonal effects and surgical ablation. This study set out to investigate the effects of anaesthesia on this mechanism. A total of 16 children undergoing surgery were recruited. They were well hydrated. The ureteric jets before and after anaesthesia were recorded using the colour and pulse wave Doppler. Of the total, 14 children showed mature (complex pattern) and two showed immature (monophasic pattern) waveforms before surgery. After anaesthesia, all showed the monophasic waveform (p=0.01). Thus, the sphincteric action of VUJ as manifest by the complexity of the ureteric jet was modified by anaesthesia by loss of the complex pattern. This supports the hypothesis that the complex pattern is a neural modulation of the simpler myogenic mechanism that produces the monophasic jet.
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PMID:Ureteric jet in the anaesthetised child. 1455 98

We conducted a retrospective analysis of 10 cases of congenital laryngeal stridor. Reports of laryngeal endoscopy and diagnosis define laryngomalacia as laryngeal flaccidity and stridor. Some authors postulate that in addition to immaturity of cartilage, there exist the possibility of laryngeal uncoordination and dyskinesia. They support this idea in cases of late presentation, neurological damage, and atypical cases related with functional state or anesthesia. Laryngeal endoscopies were carried out in 10 cases included in a cohort of subjects from a longitudinal follow-up diagnosed with neurologica damage of perinatal origin. One case was diagnosed with postoperative unilateral paralysis of vocal chord and another identified vascular ring. The eight remaining cases fulfilled laryngomalacia criteria of diagnosis, but because of their characteristics origin is not an anatomic alteration but a functional hypotonia. The need to carry out an integral study to describe co-morbidity is emphasized.
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PMID:[Laryngomalacia in a follow-up of a child development cohort for antecedents of perinatal encephalopathy. Implications for nosologic conceptualization]. 1555 28

Modeling the pharmacokinetics and pharmacodynamics of anesthetics in children is performed as a response to the clinical need for safe and efficacious administration of drugs with a low therapeutic index. Rates and concentrations of these drugs, which are the primary parameters used by anesthesiologists, depend on physiologic parameters that are markedly affected by development. Volatile anesthetics have been used for >50 years in pediatric patients. The pharmacokinetics of inhalation agents are context sensitive, but little difference between age groups has been described. These agents are not only eliminated unchanged by the lung but they are also metabolized by the liver. Halothane has Michaelis-Menten kinetics, with up to 40% of the administered dose metabolized by the liver. For volatile anesthetics, the effect measured is the minimum alveolar concentration (MAC) that leads to movement of the limb in response to skin incision in 50% of the patients studied. The MAC is higher in infants than in children and adults. Infants aged 6 months have a MAC 1.5-1.8 times the MAC observed in adults aged 40 years. Children have a greater clearance and volume of distribution of propofol than adults. In order to achieve similar plasma concentrations, children require three times the initial dose used in adults. In adults, an increased sensitivity to propofol has been demonstrated with aging, but nothing is known about the effects in children. However, it is clear that equipotent doses of propofol induce marked deleterious hemodynamic effects in infants compared with children. Regional anesthesia is used in pediatrics, both in combination with general anesthesia during surgery or alone for postoperative analgesia. A marked decrease in protein binding has been described in infants. In the postoperative period, a rapid increase in binding because of inflammation decreases the free fraction, but the free drug concentration remains constant because of the resulting decrease in total clearance. A low clearance because of liver function immaturity has been observed during the first year(s) of life for bupivacaine and ropivacaine. Pharmacodynamic interactions between general anesthesia and regional anesthesia need to be modeled. This is one of the future tasks for pharmacokineticists. Methods such as the Dixon up-and-down allocation and the isobolographic technique are promising in this field.
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PMID:Pharmacokinetic/pharmacodynamic modeling of anesthetics in children: therapeutic implications. 1677 94

The physiology of the preterm and term neonate is characterized by a high metabolic rate, limited pulmonary, cardiac and thermoregulatory reserve and decreased renal function. Multisystem immaturity creates important developmental differences in drug administration and response when compared to older children. Specific monitoring techniques are required because the neonate is not physically accessible to the anesthetist during the operation. This contribution reviews the specific pathophysiological characteristics of the newborn with relevance to anesthesia and also provides robust guidelines for the anesthetic management of the most frequent non-cardiac procedures which need surgery during the neonatal period. Consideration will also be given to the anesthetic management of very low birth-weight infants with anesthetic key issues such as avoiding hyperoxia, keeping hemodynamic parameters as stable as possible and preventing hypothermia.
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PMID:[Anesthetic management of surgery in term and preterm infants]. 1680 83

Intraoperative transcranial motor evoked potential (MEP) monitoring may help prevent neurologic injury during spine surgery. This type of monitoring may be difficult in the pediatric population under general anesthesia. We retrospectively reviewed data from 56 children, aged 2 to 18 yr, who were to undergo surgical correction of idiopathic scoliosis with MEP monitoring. Under combined isoflurane-propofol general anesthesia, before incision, we examined the minimum stimulating threshold voltage required to achieve a 50-microvolt or greater MEP response amplitude. Younger age was associated with an increase in the threshold voltage needed to elicit a sufficient MEP response. In addition, younger age was associated with longer stimulating pulse trains and greater need to adjust stimulating scalp electrodes. Body surface area, height, weight, and body mass index were also significant factors, but they were not independent predictors, after adjusting for age. Younger children received significantly lower levels of isoflurane and comparable doses of propofol, compared with older patients. Stronger stimulation needed to produce MEP responses in younger patients may reflect immaturity of their central nervous system, specifically conduction by the descending corticospinal motor tracts. Greater attention must be given to optimizing physiologic variables, limiting depressant anesthetics, and selecting the most favorable stimulating conditions in children, especially those <10 yr old.
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PMID:The effect of age on motor evoked potentials in children under propofol/isoflurane anesthesia. 1686 11

Neonatal anaesthesia dosing needs to be based on physiological characteristics of the newborn, pharmacokinetic/pharmacodynamic considerations and the adverse effects profile. Disease processes and treatments in this group are distinct from adults. Absorption, distribution and clearance are altered because of immaturity of enzyme, anatomical or physiological systems resulting in extensive variability of drug disposition in neonates. This is further compounded by pharmacogenomic influences. Population and physiological-based pharmacokinetic modelling have improved understanding of maturation and subsequent dose approximation. Postmenstrual age is a reasonable measure for maturation, although postnatal age may also have an impact. The neonatal response to drugs is also altered. Although neuromuscular monitoring is robust, there remains a need for other clinically applicable tools to assess pharmacodynamics that can provide effect feedback. In neonatal anaesthesia, a specific focus of interest is tools to assess depth of anaesthesia, sedation and pain. These tools have potential to improve effectiveness and safety.
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PMID:The pharmacology of anaesthetics in the neonate. 2103 17

A newborn requires constant vigilance, rapid recognition of the events and swift intervention during anaesthesia. The anaesthetic considerations in neonatal surgical emergencies are based on the physiological immaturity of various body systems, poor tolerance of the anaesthetic drugs, associated congenital disorders and considerations regarding the use of high concentration of oxygen. The main goal is for titration of anaesthetics to desired effects, while carefully monitoring of the cardiorespiratory status. The use of regional anaesthesia has shown to be safe and effective. Advancements in neonatology have resulted in the improvement of the survival of the premature and critically ill newborn babies. Most of the disorders previously considered as neonatal surgical emergencies in the past no longer require immediate surgery due to new technology and new methods of treating sick neonates. This article describes the common neonatal surgical emergencies and focuses on factors that affect the anaesthetic management of patients with these disorders.
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PMID:Anaesthetic consideration for neonatal surgical emergencies. 2329 85


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