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L Halpern

Publications and source records attributed to L Halpern.

18 recordsLinked to original sources
PubMed1998

Recovery characteristics of propofol anaesthesia, with and without nitrous oxide: a comparison with halothane/nitrous oxide anaesthesia in children.

Few studies have examined whether nitrous oxide influences the recovery characteristics of propofol anaesthesia. The present study examined the effect of nitrous oxide on the recovery characteristics of propofol anaesthesia, and compared these data with those for halothane/nitrous oxide anaesthesia. Sixty children aged 3-12 years were assigned at random to receive one of three maintenance regimens: propofol with or without nitrous oxide (70%) or halothane/nitrous oxide (70%). During propofol/N2O anaesthesia, the infusion rate of propofol (180 +/- 39 micrograms.kg-1.min-1) required to maintain the mean arterial pressure and heart rate within 20% of the baseline values was significantly less than that during propofol/O2 (220 +/- 37 micrograms.kg-1.min-1; P < 0.005). The time from discontinuation of anaesthesia to eye-opening (11 +/- 6 min), to response to commands (12 +/- 6 min), and to return of full wakefulness (21 +/- 10 min) after propofol/N2O were similar to those after propofol/O2, but significantly less (by approximately 30%) than those after halothane (P < 0.05). The overall incidence of emesis after propofol/N2O (53%) was greater than that after propofol/O2 (17%, P < 0.05) and comparable to that after halothane/N2O (58%). These data suggest that N2O has little effect on the rate of recovery after propofol, but significantly increases the incidence of postoperative emesis, thereby attenuating one of the main attributes of propofol anaesthesia.

Anesthesia Recovery Period↗
PubMed1996

Behavioral intervention and post-natal growth in full-term intrauterine growth retarded (IUGR) infants.

The purpose of this study was twofold: (1) to describe the patterns of post-natal growth in full-term infants as a function of IUGR and (2) to assess the impact of an individualized behavioral feeding intervention with the mothers on these patterns of infant growth. Eighty-eight (88) full-term infants, including 54 with IUGR, half of whom received behavioral intervention were included. Weight, length, skinfold thickness, head circumference and Ponderal Index were measured at birth and at 1, 4, 8, 12, and 18 months. Results show positive intervention effects between birth and 1 month in weight, length, skinfold thickness, and Ponderal Index. However, there were no intervention effects at subsequent ages. No evidence was found for catch-up growth in full-term IUGR infants in weight, length, and head circumference. We conclude that an individualized behavioral feeding intervention can accelerate early growth in IUGR infants, but the positive effects on growth are only seen while the intervention lasts (between birth and 1 month). On most parameters of physical growth, there is no lasting catch-up growth over the first 18 months in IUGR full-term infants.

Body Height↗
PubMed1994

The most proximal and accurate site for sampling end-tidal CO2 in infants.

The most proximal site to sample end-tidal CO2 with reasonable accuracy in infants during pulmonary ventilation using a Mapleson D circuit remains controversial. The utilisation of high fresh gas flow near the site of gas sampling dilutes the expired gas and causes an underestimation of end-tidal CO2. In this study a laboratory model was used to identify, qualitatively and quantitatively, the most proximal site in the Mapleson D circuit where the measurement of end-tidal CO2 is not influenced by mixing with fresh gas. A fresh gas flow rate of between 2 and 15 L.min-1 with a respiratory rate of 20-30.min-1 and a tidal volume of 30-100 ml.min-1 was evaluated. This experiment was divided into two parts. Firstly, an infant lung model was used to visualize the site of mixing between fresh gas and smoke-labelled exhaled gas. Secondly, fresh gas flow and expired gas flow were controlled and the end-tidal CO2 concentration was measured along the length of the anaesthetic circuit to identify the site of mixing of fresh gas and expired gas during steady-state conditions. Three expired gas flows were studied at six fresh gas flows. In all our studies, the rate of fresh gas flow and expired gas flow influenced the site of mixing and degree of dilution but no mixing was observed distal to the point at which the endotracheal tube connector narrows to the diameter of the endotracheal tube (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Airway Resistance↗
PubMed1988

Wide-angle one-way wave equations.

A one-way wave equation, also known as a paraxial or parabolic wave equation, is a differential equation that permits wave propagation in certain directions only. Such equations are used regularly in underwater acoustics, in geophysics, and as energy-absorbing numerical boundary conditions. The design of a one-way wave equation is connected with the approximation of (1-s2)1/2 on [-1,1] by a rational function, which has usually been carried out by Padé approximation. This article presents coefficients for L2, L infinity, and other alternative classes of approximants that have better wide-angle behavior. For theoretical results establishing the well posedness of these wide-angle equations, see the work of Trefethen and Halpern ["Well-posedness of one-way wave equations and absorbing boundary conditions," Math. Comput. 47, 421-435 (1986)].

Acoustics↗
PubMed1977

Carbamazepine--a double-blind comparison with phenytoin.

In a double-blind crossover study, carbamazepine and phenytoin were compared as single anticonvulsants in 47 patients with focal and major generalized seizures. Each drug provided superior seizure control in about half the patients, but significantly fewer patients had objective side effects while taking carbamazepine. Neuropsychologic testing showed improved performance in cognitive function and emotional status of patients while and carbamazepine. No hematotoxic complications arose, but vigilant follow-up is advised. Mean serum level of carbamazepine was 9.3 microng per milliliter with a suggested therapeutic range of 8 to 12 microng per milliliter reached by eventual doses of 16 to 20 mg per kilogram. Carbamazepine offers an independent choice of improved seizure control with a possibility of fewer side effects.

Adult↗
PubMed1976

Population cancer screening.

Controlled trials to evaluate mass screening programs for cancer detection have been singularly lacking. High cost, lack of medical manpower, and low yield have contributed to this problem. A new program in cancer detection (CANSCREEN) has been developed jointly by The Fox Chase Cancer Center in Philadelphia and the Preventive Medicine Institute in New York City. This program attempts to provide a quality cancer-detection examination with increased cost effectiveness. Features include: 1) a self-administered questionnaire on medical history, symptoms, and risk factors; 2) nonphysican examiners; 3) risk-facotr analysis with a predetermined decision logic to determine type and periodicity of examination; and 4) primary intervention (health education). This collaborative program between two institutions in two cities demonstrates the feasibility of introducing similar programs elsewhere. A data base shared by cooperating centers permits information on all patients to be used for evaluation of new techniques, end results, etc. A randomized controlled trial has been designed to evaluate the effectiveness and efficiency of the questionnaire alone and of the questionnaire and examination.

Breast Neoplasms↗