One-step transformation of tricyclopentabenzene (trindane, C(15)H(18)) to bicyclo(10.3.0)pentadec-1(12)ene- 2,6,7,11-tetrone (C(15)H(18)O(4)) and its aldol product, 12-hydroxy-16-oxatetracyclo(10.3.1.0.(1,5)0(7,11))hexadec-7(11)ene-2,6-dione (C(15)H(18)O(4)).

[reaction: see text] Ozonolysis of 1 largely results in 2 and 3, having features similar to several classes of natural products. The retention of the C(15) pericycle suggests preference for the cleavage of pi-bonds endo to the cyclopentane ring. This unique property of trindane offers opportunities for synthesis of complex natural products from this hydrocarbon that can be made in quantity by acid-catalyzed trimerization of cyclopentanone.

Anaesthetic considerations for magnetic resonance imaging.

Magnetic resonance imaging (MRI) has become an increasingly popular non-invasive radiological diagnostic procedure, with several distinct advantages over computerised tomography (CT). The images are produced using a strong (1.5-Tesla) magnetic field and radiofrequency (RF) pulses. Due to the effects of the strong magnetic field, certain groups of patients with implanted ferromagnetic objects and women in their first trimester of pregnancy are precluded from undergoing MRI. While most of the patients undergo MRI awake or with light sedation, few need heavy sedation or general anaesthesia. The problems related to anaesthesia in MRI include the constant presence of a strong magnetic field, the RF pulses and their effect on the anaesthesia machine, monitoring devices, magnetically coded material, and loose ferromagnetic objects. In this article, the current availability of MRI-compatible anaesthesia machine, various monitoring devices, and safe conduct of anaesthesia during MRI for patients of all ages are discussed. In addition, the implications of the strong magnetic field on patient resuscitation inside the MRI suite and the recommended procedure for a successful outcome are outlined.

Anesthesia for selected procedures.

This article reviews selected procedures for which a particularly close working relationship between the surgeon and the anesthesiologist is essential for patient safety. Anesthetic considerations for upper and lower gastrointestinal endoscopies, bronchoscopy for aspirated foreign bodies, resection of mediastinal masses, thoracotomies for procedures requiring one-lung anesthesia, and surgery for burn patients are reviewed.

Anesthesia outside the operating room.

Many new diagnostic and surgical procedures rely on immobile equipment such as computed tomography or magnetic resonance scanners, biplanar fluoroscopes, or radiotherapy units. To facilitate these procedures in infants and children, anesthesiologists must provide services in a variety of unique environments. This article reviews the anesthetic equipment and techniques that have been adapted to provide anesthesia for children outside the operating room.

Increased sensitivity of the isometric contraction of the neonatal isolated rat atria to halothane, isoflurane, and enflurane.

Isolated atria from neonatal (0-5 day old) and adult (50 +/- 5 day old) rats were perifused in oxygenated Kreb's Henseleit solution at 30 +/- 0.5 degrees C and exposed to four different concentrations of halothane, isoflurane, or enflurane while isometric contractile tension was recorded and compared with control atria. ED50 values (mM of anesthetic required to produce 50% reduction in contractile tension) of neonates for halothane (0.18 +/- 0.01), isoflurane (0.41 +/- 0.05), and enflurane (0.41 +/- 0.04) were significantly lower than those of adults (0.35 +/- 0.02, 0.80 +/- 0.05, and 1.15 +/- 0.05, respectively). Furthermore, neonatal ED50 calculated as per cent of adult ED50 was significantly less for enflurane (35%) than for halothane (54%) or isoflurane (51%).

Dopamine reverses cardiovascular depression of toxic doses of pentobarbitone in dogs.

Pentobarbitone, 20 mg X kg-1 IV followed by infusion of 25 mg X kg-1 X hr-1, produced a progressive decrease in mean arterial pressure in dogs from 113 +/- 17 mmHg (SD) after one hour of infusion to 82 +/- 21 mmHg after 3.5 hours and to 49 +/- 22 mmHg after 5.5 hours. EEG silence occurred at 3.6 +/- 0.6 hours. In dogs similarly treated with pentobarbitone, a two hour infusion of dopamine 5 micrograms X kg-1 X min-1 beginning at the time of EEG silence prevented the further decrease in pressure and restored pressure to 87 +/- 18 mmHg. The mechanism for this effect of dopamine was an increase in cardiac output as systemic vascular resistance was unaffected by dopamine. The cardiac output increase was mainly the result of an increase in stroke volume as heart rate increased only slightly. Since reduced stroke volume was the main reason why pentobarbitone lowered blood pressure, the effect of dopamine on stroke volume and thus on blood pressure makes it an appropriate antagonist to the cardiovascular effects of toxic doses of pentobarbitone.

Effect of age on epinephrine-induced arrhythmias during halothane anaesthesia in pigs.

The effect of age on the arrhythmogenicity of epinephrine during halothane anaesthesia was studied in pigs of two different age groups. At a stable alveolar concentration of 0.84 volumes per cent halothane, ventricular arrhythmias could not be elicited in one- to three-day-old pigs by a 100 micrograms X kg-1 infusion of epinephrine. PVCs were produced in 50- to 55-day-old pigs at a mean epinephrine dose of 9.55 micrograms X kg-1. Heart rate, systolic blood pressure, and rate-pressure product were significantly higher before and during the epinephrine infusion in the 50- to 55-day-old pigs. It is concluded that there is an age dependent effect upon epinephrine induced arrhythmias during halothane anaesthesia in pigs.

Neonatal lung abscess: resection using one-lung anesthesia.

Three neonates with lung abscess unresponsive to antibiotic therapy underwent successful resection of infected lobes with the aid of one-lung anesthesia. This was accomplished by selective endobronchial intubation of the opposite lung and obstruction of the ipsilateral main bronchus with a Fogarty balloon-tipped catheter. This valuable technique provides protection against tracheobronchial spillage of purulent material and results in the rapid recovery of these seriously ill neonates.

Comparison of cardiovascular effects of thiopental and pentobarbital at equivalent levels of CNS depression.

Thiopental and pentobarbital have been used in high doses to protect the brain from injury following hypoxia or to reduce intracranial pressure. This study was performed to determine whether these barbiturates differ in cardiovascular effects when present in plasma concentrations that produce equivalent CNS effects. The effects of thiopental and pentobarbital on heart rate, stroke volume/kg, cardiac output/kg, systemic vascular resistance, mean arterial pressure, and central venous pressure were statistically indistinguishable at plasma concentrations of each barbiturate ranging from 50% to 100% of their concentration producing EEG silence. Three of the seven dogs given thiopental developed ventricular bigeminy at plasma concentrations ranging from 45% to 65% of their concentration producing EEG silence. Lidocaine (1.4-2.0 mg/kg intravenously) reversed the bigeminy to sinus rhythm. When given more than the amount needed to produce a flat EEG, five of the seven dogs given thiopental died, but all dogs given pentobarbital survived. Pentobarbital may be a better choice than thiopental when large doses are indicated.

Anaesthetic implications of neonatal necrotizing enterocolitis.

A retrospective analysis of infants with necrotizing enterocolitis was done to evaluate the effects of preoperative abnormalities upon anaesthesia and mortality. Mortality was significantly increased in infants weighing less than 1500 grams (p less than .001). Sixty-nine per cent of the infants had hyaline membrane disease and 35 per cent had platelet counts less than 50 X 10(9) cells/litre (50,000/mm3). Perioperative problems include peritonitis, sepsis, hypovolaemia, acidosis, and prematurity. Other ramifications of prematurity and anaesthesia are discussed.