Intoxication of the fetus by a local anesthetic. A newly recognized complication of maternal caudal anesthesia

Reporting a fatality during tumescent liposuction

Deaths of patients during elective surgery have drawn attention to the danger of anesthesia. Tumescent local anesthesia is subcutaneous infiltration of large volumes of dilute lidocaine with epinephrine to produce vasoconstriction while delivering anesthesia over large areas without lidocaine toxicity. This report documents the case of a 38-year-old woman who attended an outpatient clinic to undergo liposuction of the abdomen and bilateral hips and thighs. According to one witness, around 30 min after anesthesia administration, the victim suffered an episode of tonic-clonic convulsion. When the emergency medical services arrived the patient was in asystole. She died in spite of attempted cardiopulmonary resuscitation. The patient had no significant past medical history including no history of allergies or any known complications with anesthesia. A complete autopsy was performed and possible causes of death such as myocardial infarction, aspiration of food or foreign body, and pulmonary embolism were discarded. Anaphylactic shock was considered a possible but unlikely explanation for the fatality. Toxicological analyses revealed the presence of lidocaine and mepivacaine in heart blood, at concentrations of 4.9 and 16.2mg/L, respectively. All drugs involved in the case were detected using gas chromatography with nitrogen-phosphorus detector and confirmed using gas chromatography-mass spectrometry full scan mode after solid-phase extraction using Chem-Elut columns. An additional high-performance liquid chromatography coupled to diode-array detection screening also obtained the same results. Based on the autopsy findings, case history, and toxicology results, the forensic pathologists ruled that the cause of death was an overdose of local anesthetic agents. The Court of Law ruled the death as an involuntary homicide due to gross negligence.

Neonatal seizures: a clinician's overview

Seizures are the most frequent neurological event in newborns (NBs), provoked often by noxae not apt to cause them in later life. This is because receptor families of excitatory amino acids (EAA) are overexpressed at this stage of brain ontogenesis, which is also why most neonatal seizures rapidly abate, even when neurological deficits persist. The brain's immaturities dictate distinct seizure phenotypes. A classification proposed in the late 1960s has been criticized, and a new one has been advocated, based on correlations between EEGs and behaviors, leading to a classification of seizures into 'epileptic' and 'non-epileptic'. The taxonomic pitfalls of these classifications are discussed, and the notion advanced that many seizures fail to fulfil the criteria to label them as epileptic. While etiological factors have changed in time, the striking dichotomy in outcome has persisted. Many etiologies, often multifactorial, are unique in NBs, and they are discussed with reference to diagnosis and therapies. Four syndromes of NB seizures, accepted into the International Classification of the Epilepsies, are critically analyzed, some appearing to rest on fragile grounds. Controversies persist whether seizures per se are injurious to the immature brain. Clinical studies suggest that neither duration in days or length of seizure phenotypes correlates with outcomes, the most valid prognostic indices being offered by etiologies and by patterns of EEG polygraphy. However, because most seizures are symptomatic, it may be difficult to distinguish morbidity due to underlying pathology from that possibly added by seizures. Animal experiments suggested that they are injurious. The theory of energy failure, postulated to cause a cascade of events leading to inhibitions of DNA, proteins, lipids and disrupted neuronal proliferation, synaptogenesis, myelination, has largely been disproved. Brains of immature animals have been shown to have the oxidative machinery needed to fulfill energy demands, even during status convulsivus. They are also capable of using anaerobic metabolism and require less ATP when aerobic energy production ceases. Recent explanations for the injurious consequences of hypoxic ischemia and of prolonged convulsions postulate that neuronal damage occurs from excessive release of EAA which, by binding to their ligand-gated ionic receptors, cause a large influx of Ca2+, resulting in cell death. Because of the overabundance of EAA receptors in early ontogenesis, the excitotoxic hypothesis would appear attractive, but some observations militate against it. Among these is the dissociation found between the focal neurotoxicities induced by EAA injected into the brain and their absence following the concomitant convulsions. The latter are not blocked by pretreatment with EAA antagonists, while these prevent injuries caused by the injected EAA. There is no convincing evidence that excessive release of EAA occurs during NBs' seizures. Even if it does occur, it has been shown that immature neurons have a better capacity to self-protect from increased Ca2+ influx, and also that direct application of glutamate to immature neurons leads to significantly lower Ca2+ influx. These data raise doubts about the postulated excitotoxicity caused by NBs' seizures, being consistent with the fact that no one, so far, has observed neuronal damage from drug-induced convulsive states in NBs. Lack of overt neuronal injuries does not preclude that long-term subtle changes might be induced by noxae apt to provoke transient ictal events. Thus models developed in our laboratories demonstrate that long-term epileptogenicity results following postnatal O2 deprivation without evidence of neuronal injuries or of long-term behavioral or electrophysiological alteration. However, both age at which hypoxia occurs and specific proconvulsant methods used strictly determine whether increased epileptogenicity will occur.

The place of caudal anaesthesia in obstetrics

Present day trainee anaesthetists could be forgiven if they finished their anaesthetic training believing that caudal anaesthesia in obstetrics is not only unnecessary, but dangerous and a relic of the past. Many anaesthetic texts teach applications and techniques which are little or no advance on the teachings of Hingson and Edwards in 1942 and reflect nothing of the true value and application of this valuable block. This paper presents a critical review of these texts and of the results of the use of the block in a busy obstetric unit.

Heart block after intravenous lidocaine in an infant

A 14-day-old infant received intravenous lidocaine (2 mg X kg-1) at the conclusion of cataract surgery to prevent coughing from tracheal tube stimulation. Within 30 seconds the infant developed high-grade AV heart block and a ventricular rate of 40. Following brief resuscitation efforts, the patient had a normal cardiac rhythm, blood pressure and respiratory pattern. Intravenous lidocaine may be followed by major disturbances in cardiac rhythm and rate. Cautious titration of small doses should decrease the potential for adverse effects.

Brain-to-blood and saliva-to-blood mepivacaine ratios in rats

Mepivacaine hydrochloride, 25 and 50 mg/kg sc (with sacrifice at 15 min) produced higher (p less than 0.005) drug levels in neonate (24--36-hr-old) rat brain and blood than in adult rat brain and blood; however, there was no significant difference in the brain-to-blood ratio of the drug between neonates and adults at either dose level. Intraarterial infusion of mepivacaine hydrochloride (20 micrograms/min) in adult rats resulted in measurable (GLC) mepivacaine base levels in pilocarpine-induced parotid salivary secretions collected throughout 30- and 45-min infusion periods. The saliva-to-blood ratios (+/- SEM) of mepivacaine base were 0.64 +/- 0.13 after a 30-min infusion and 2.13 +/- 0.48 after a 45-min infusion.

Diagnosis, treatment, and follow-up of neonatal mepivacaine intoxication secondary to paracervical and pudendal blocks during labor

Seven infants developed mepivacaine intoxication secondary to accidental injection during paracervical or pudental blocks or both. All presented with unexplained neonatal depression at birth, tonic seizures (often with apnea) within six hours, and characteristic neurologic findings. Twenty-four-hour urinary excretion produced 12.7 to 37.4 mg, exchange transfusions less than 1.02 to 3.5 mg, and gastric drainage or lavage or both 0.63 to 1.26 mg of mepivacaine. Thus promotion of urinary excretion is the treatment of choice. All six survivors are seizure free and neurologically and developmentally normal at one to 4 1/2 years. With early diagnosis and prevention of severe perinatal hypoxia, the prognosis from intoxication alone is very good.

Foetal hypoxia--an anaesthetist's approach to classification and prevention

Nearly one third of perinatal deaths are due to hypoxia occurring during pregnancy and labour. Many factors contribute to foetal hypoxia and in order to group these into orderly categories a classification of hypoxia, which is familiar to anaesthetists, has been applied to the maternal and foetal circulations. This theoretical approach forms a logical guide to our understanding the cause, prevention and treatment of foetal hypoxia.

Ventricular tachycardia in a neonate with mepivacaine toxicity

An unusual case of mepivacaine toxicity with ventricular tachycardia in a newborn infant is presented. The mepivacaine probably reached the infant by direct injection into the scalp. Effective removal of the drug by gastric lavage was demonstrated. Exchange transfusion may also have been instrumental in the infant's survival by reducing the high blood concentration of mepivacaine.

Brain tissue levels in a fatal case of neonatal mepivacaine (Carbocaine) poisoning

A fatal case of mepivacaine poisoning in a newborn infant is reported. Regional brain tissue concentrations of mepivacaine were determined by a sensitive and specific gas chromatographic-mass spectrometric method. The brain tissue levels in this patient were higher than those previously reported, possibly due to alkalosis occurring several hours prior to the infant's death.

Concentration of lidocaine hydrochloride in newborn gastric fluid after elective caesarean section and vaginal delivery with epidural analgesia

Lidocaine concentrations were measured after vaginal delivery or Caesarean section with epidural anaesthesia in samples of maternal and umbilical blood and in newborn gastric contents. The pH of the gastric aspirate was also determined in a number of neonates. Gastric lidocaine concentrations were higher and the pH was lower after vaginal delivery in comparison to Caesarean section. A significant inverse correlation exists between gastric pH and gastric lidocaine concentration, Neonate gastric lidocaine concentration was significantly higher than in maternal or umbilical venous plasma after vaginal delivery, but not after Caesarean section. Due to these differences, gastric lavage for the treatment of neonatal lidocaine intoxication may be more beneficial in reducing foetal systemic local anaesthetic concentration after vaginal than after elective abdominal delivery.

Local-regional anesthesia during childbirth: effect on newborn behaviors

Administration of local-regional anesthesia during norgnal deliveries was correlated significantly with newborn behaviors as evaluated by the Brazelton neonatal assessment scale. Three days after birth, infants whose mothers received local-regional anesthesia were more irritable and motorically less mature than those infants whose mothers were not medicated.