Syndrome of inappropriate ADH secretion in a woman with preeclampsia.

While preeclampsia is common in pregnancy, associated hyponatraemia is rare with very few cases reported in the literature. We report the case of a previously healthy nulliparous woman who presented at 34 weeks' gestation with hypertension and proteinuria. On admission her serum sodium was 122mmol/L and by day 6, in the absence of fluid restriction, it had fallen to 116mmol/L. Urine and plasma osmolalities suggested a syndrome of inappropriate antidiuretic hormone secretion. She was delivered on the sixth day by caesarean section because of fetal distress and worsening preeclampsia. Postoperatively fluid intake was restricted and her sodium normalised within 48h. Preeclampsia results in a low effective circulating volume which can cause a non-osmotic release of antidiuretic hormone and a resultant increase in the urine/plasma osmolality ratio to greater than 1. In patients with preeclampsia, hyponatraemia may further increase the risk of seizures and should therefore be closely monitored and treated without delay.

Recognition and management of maternal cardiac disease in pregnancy.

Heart disease is a leading cause of maternal death. The aim of this study is to review the most common causes of cardiac disease, highlight factors that should be recognized by the clinician, and address recent advances in the anaesthetic management of these patients. Incipient cardiac disease, including peripartum cardiomyopathy, myocardial infarction and aortic dissection, accounts for approximately one in six maternal deaths. The keys to successful diagnosis and management of incipient disease are: a high index of suspicion, particularly in women with known risk factors for cardiovascular disease; a low threshold for radiological investigations; early cardiology input; and invasive monitoring during labour and delivery. Echocardiography is a safe, non-invasive test, under-used in pregnancy. Management of pregnant women with pre-existing cardiac problems should be undertaken by multidisciplinary teams in tertiary centres. In women with pre-existing cardiac disease wishing to proceed to term, cardiac status must be optimized preoperatively and planned elective delivery is preferable. Vaginal delivery is preferable, and with careful incremental regional anaesthesia is safe in most women with cardiac disease. The presence of adequate systems for early detection, appropriate referral to specialist centres, and timely delivery with multidisciplinary support can minimize the serious consequences of poorly controlled heart disease in pregnancy.

Nasotracheal intubation for head and neck surgery.

Nasotracheal intubation offers the head and neck surgeon more scope for surgical manoeuvre in operations of the mouth, pharynx, larynx and also the neck. Concern over the complications of using this route of intubation and lack of training may be limiting its use. A thorough knowledge of the anatomy, benefits of using nasal vasoconstrictors and attention to technique are prerequisites to maintaining the skill. This article reviews each of these topics and aims to encourage the appropriate use of nasotracheal intubation in current practice.

Assessment of ropivacaine as a local anesthetic for skin infiltration in skin surgery.

BACKGROUND: There has been limited examination of the use of ropivacaine, a relatively new amide local anesthetic, for skin surgery following local infiltration. Initial studies of ropivacaine show it to have a rapid onset and long duration of action. OBJECTIVE: To establish the injection characteristics of different concentrations of ropivacaine and to compare the pain of infiltration of ropivacaine with lidocaine 2% + epinephrine 1:80,000. METHOD: A double-blind placebo-controlled study was carried out on 18 healthy volunteers. Four concentrations of ropivacaine (1, 2, 5, and 7.5 mg/ml) were injected intradermally. Normal saline was used as the control. Sensation for pinprick was used to assess the onset and duration of anaesthesia. Pain of infiltration of ropivacaine and saline was additionally compared with lidocaine 2% + epinephrine 1:80,000. RESULTS: Pain of ropivacaine infiltation increased with increasing strength, but only 5 mg/ml was significantly more painful than the control P =.002). Lidocaine and epinephrine infiltration was significantly more painful than the control P =.0002) and 7.5 mg/ml ropivacaine (P =.0005). Mean times to reach full anesthesia were 74 seconds for 5 mg/ml and 51 seconds for 7.5 mg/ml. Mean times to regain full sensation were estimated as 692 minutes for 5 mg/ml and 773 minutes for 7.5 mg/ml. A vasoconstrictor effect was noted in the ropivacaine sites. CONCLUSION: Ropivacaine has a rapid onset and long duration of action. Ropivacaine produces vasoconstriction which may be clinically relevant. Even at maximum strength ropivacaine is less painful to inject than lidocaine with epinephrine.

Spatial and temporal trends of contaminants in Canadian Arctic freshwater and terrestrial ecosystems: a review.

The state of knowledge of contaminants in Canadian Arctic biota of the freshwater and terrestrial ecosystems has advanced enormously since the publication of the first major reviews by Lockhart et al. and Thomas et al. in The Science of the Total Environment in 1992. The most significant gains are new knowledge of spatial trends of organochlorines and heavy metal contaminants in terrestrial animals, such as caribou and mink, and in waterfowl, where no information was previously available. Spatial trends in freshwater fish have been broadened, especially in the Yukon, where contaminant measurements of, for example, organochlorines were previously non-existent. A review of contaminants data for fish from the Northwest Territories, Yukon and northern Quebec showed mercury as the one contaminant which consistently exceeds guideline limits for subsistence consumption or commercial sale. Lake trout and northern pike in the Canadian Shield lakes of the Northwest Territories and northern Quebec generally had the most elevated levels. Levels of other heavy metals were generally not elevated in fish. Toxaphene was the major organochlorine contaminant in all fish analyzed. The concentrations of organochlorine contaminants in fish appear to be a function not only of trophic level but of other aspects of the lake ecosystem. Among Arctic terrestrial mammals, PCBs and cadmium were the most prominent contaminants in the species analyzed. Relatively high levels (10-60 micrograms g-1) of cadmium were observed in kidney and liver of caribou from the Yukon, the Northwest Territories and northern Quebec, with concentrations in western herds being higher than in those from the east. For the organochlorine contaminants, a west to east increase in zigma PCBs, HCB and zigma HCH was found in caribou, probably as a result of the predominant west to east/north-east atmospheric circulation pattern which delivers these contaminants from industrialized regions of central and eastern North America to the Arctic via long-range atmospheric transport. Radiocesium contamination of lichens and caribou has continued to decrease. Significant contamination by PCBs and lead of soils and vascular plants was observed in the immediate vicinity and within a 20-km radius of DEW line sites in the Canadian Arctic. There was also evidence for transfer of PCBs from plants to lemmings. There was no evidence, however, that large mammals such as caribou living in the general area of the DEW line sites had elevated levels of PCBs. There is very limited temporal trend information for most contaminants in biota of Arctic terrestrial and freshwater environments.

Behavior of captive american kestrels hatched from o,p'-dicofol exposed females.

A two-generation laboratory study was conducted on captive American kestrels (Falco sparverius) to investigate the possible behavioral alterations from the compound o,p'-dicofol. Paired females were exposed to three levels of dicofol by oral gavage. Adults of the second generation, exposed only via the maternal dose of o,p'-dicofol at 5- and 20-mg/kg, displayed negatively correlated changes in reproductive behaviors. Second generation females showed a significant difference (p < 0.05) from control birds in the miscellaneous behavior category, where more time was spent picking at the rope perch, watching flies, laying down on the perch and other such displacement activities. Second generation 5-mg/kg males completed significantly fewer copulations (p < 0.05) than the corresponding control birds. The number of attempted or failed food transfers (a pair bonding activity) was also significantly higher (p < 0.05) in the second generation 5-mg/kg male group. Trials were conducted on second generation males to determine aggressiveness of these individuals when placed in a competitive arena. Primary perch sites and food items were obtained by control birds significantly (p < 0.05) more often than dicofol-exposed males. A bird's maternal dose had a significant negative effect (p < 0.05) on its ability to achieve a high rank order position.

Unrecognized "crack" cocaine abuse in pregnancy.

We report a case of "crack" cocaine abuse in a pregnant patient associated with haematuria, proteinuria, haemolytic anaemia, renal impairment, thrombocytopenia and pulmonary oedema. The case illustrates the problems for clinicians where unrecognized cocaine abuse interferes with the diagnosis and management of a complicated pregnancy. In addition, we discuss the principles for the safe conduct of anaesthesia in the pregnant cocaine abuser.

Auditory, ocular, and facial complications of central neural block. A review of possible mechanisms.

BACKGROUND AND OBJECTIVES: The purpose of this review is to draw together a collection of uncommon complications of central neural block that affect the cranial nerves. There have been a small number of case reports, some of which have included a possible mechanism of the nerve dysfunction, but there is no prior review that collected them together and discussed the possible mechanisms. METHODS: Published case reports were identified by searching Medline of the British Medical Association and the Silver Platter CD-ROM library. In addition, the Medical Defence Union and Medical Protection Society were contacted to find cases that were unpublished but the subject of medical negligence lawsuits. RESULTS: The authors collected these cases together to increase awareness of alarming complications. If such cases are recognized for what they are, then the prognosis is good; however, delayed diagnosis can make them a cause of great anxiety and possible litigation. CONCLUSIONS: Increased awareness of these complications can decrease the likelihood of litigation by early diagnosis and explanation. Their mechanisms are not fully understood but the likely possibilities have been discussed. Further work is needed to establish the incidence of these problems, as it is likely that many cases are not diagnosed and not reported.

Spinal anaesthesia for caesarean section: comparison of 22-gauge and 25-gauge Whitacre needles with 26-gauge Quincke needles.

We have studied 150 women undergoing elective Caesarean section under spinal anaesthesia. They were allocated randomly to have a 22-gauge Whitacre, a 25-gauge Whitacre or a 26-gauge Quincke needle inserted into the lumbar subarachnoid space. The groups were compared for ease of insertion, number of attempted needle insertions before identification of cerebrospinal fluid, quality of subsequent analgesia and incidence of postoperative complications. There were differences between groups, but they did not reach statistical significance. Postdural puncture headache (PDPH) was experienced by one mother in the 22-gauge Whitacre group, none in the 25-gauge Whitacre group and five in the 26-gauge Quincke group. Five of the six PDPH occurred after a single successful needle insertion. Seven of the 15 mothers in whom more than two needle insertions were made experienced backache, compared with 12 of the 129 receiving two or less (P < 0.001). We conclude that the use of 22- and 25-gauge Whitacre needles in elective Caesarean section patients is associated with a low incidence of PDPH and that postoperative backache is more likely when more than two attempts are made to insert a spinal needle.

Secondary poisoning hazard of fenthion to American kestrels.

The possibility that fenthion, an organophosphorus pesticide, could represent a secondary poisoning hazard to birds of prey was tested, using American kestrels (Falco sparverius) and house sparrows (Passer domesticus) as representative models of a naturally occurring predator-prey interaction. Fourteen kestrels were presented with live sparrows exposed previously to perches containing Rid-A-Bird 1100 solution (11% fenthion active ingredient). Eleven kestrels died within twenty-four h after consuming one fenthion-exposed sparrow. Two kestrels died after consumption of a second fenthion-exposed sparrow on day 2, and a final kestrel died after partially consuming a third fenthion-exposed sparrow on day 3. Brain cholinesterase (ChE) activity in kestrels was depressed to levels diagnostic of poisoning by a ChE-inhibiting compound. The majority of fenthion contamination of sparrows was external, with the highest amounts measured on the feet. The detection of fenthion residues in kestrel gastro-intestinal tracts confirmed secondary fenthion poisoning.

Comparative study of the effects of air or saline to identify the extradural space.

Fifty women in labour were allocated randomly to receive either air or saline to assist in the identification of the extradural space by the loss of resistance technique. A study volume of 4 ml of air or saline was used before 0.5% bupivacaine 8 ml and the spread of analgesia was followed for 30 min. The first segment blocked, time of onset, number of blocked segments and height of block were comparable in the two groups. At 30 min, there were eight patients with an unblocked segment in the air group, compared with two in the saline group (P less than 0.01). All unblocked segments were blocked subsequently by further doses of bupivacaine. We conclude that air is more likely than saline to produce unblocked segments in the initiation of extradural analgesia in labour.

Atropine and hyoscine.

The drugs atropine and hyoscine are reviewed in the context of their use by anaesthetists. The results of recent studies are stressed and guidelines given for use of these drugs in modern anaesthetic practice.