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Biomedical subjects

E Lear

Publications and source records attributed to E Lear.

26 records · Page 2Linked to original sources
PubMed1982

Intrapulmonary shunting during induced hypotension.

The effect of sodium nitroprusside (SNP) and nitroglycerin (TNG) on pulmonary shunting (Qs/Qt) in 14 consenting adults [nine with normal lung function and five with chronic obstructive pulmonary disease (COPD)] was studied under general anesthesia. Qs/Qt significantly increased (p less than 0.005) from 5.19% to 8.81%, whereas pulmonary arterial pressure (PAP) decreased from 18.5 to 8 torr (p less than 0.005) and pulmonary vascular resistance (PVR) decreased from 235 to 147.75 dynes . sec/cm5 (p less than 0.025) when SNP was administered to patients with normal lung function. Nitroglycerin increased Qs/Qt from 5.13% to 6.19% (p less than 0.005), whereas PAP decreased from 18 to 10 torr (p less than 0.005) and PVR decreased from 237 to 162.6 dynes . sec/cm5 (p less than 0.025) in these patients. In patients with COPD, SNP and TNG produced no significant changes in Qs/Qt, PAP, or PVR. Cardiac output remained unchanged in both groups of patients. Various mechanisms to explain these results can be postulated. When hypotension is induced in patients with normal pulmonary function. PAP decreases and the effect of gravity puts more blood through dependent areas where most of the shunt units are. In patients with COPD, destructive vascular changes increase PAP, preventing vasodilators from decreasing PVR. In addition, dilation of hypoxic pulmonary vasoconstriction (if present) by SNP and TNG will occur independent of the two previously mentioned mechanisms. These results provide evidence that SNP- and TNG-induced hypotension may cause significant impairment in pulmonary gas exchange in patient with normal lung function. In patients with COPD pulmonary gas exchange is not affected after deliberate hypotension with SNP or TNG.

Adult↗
PubMed1976

Gas-chromatographic quantitation of theophylline in small volumes of plasma.

We describe a rapid procedure for quantitating theophylline in 100-mul plasma samples by use of a gas-liquid chromatograph equipped with a flame ionization detector. This methos is especially useful for monitoring theophylline concentrations in serum or plasma of infants, because sufficiently large blood samples can be readily obtained from a heel prick. The method is specific for theophylline in the presence of caffeine, theobromine and phenobarbital. For plasma concentrations equal to or greater than 5 mg/liter the average daily coefficient of variation was less than 7% while the coefficient of variation from day to day was less than 11%. The same approach can also be used to measure concentrations of phenobarbital in small volumes of plasma or serum, and is readily adapted to determination of theophylline and phenobarbital in larger samples.

Amobarbital↗
PubMedDate not supplied

Atypical pseudocholinesterase: a clinical report.

The safe conduct of anesthesia demands careful evaluation of the previous experience of patients under anesthesia and surgical operation, as well as that of their families. Untoward responses that may recur with subsequent anesthetic procedures should be documented and patients informed, as the need dictates. Two cases of prolonged apnea following single intubating doses of succinylcholine could not have been predicted by the patient's preanesthetic history. As a result of these problems, the authors recommend more careful preanesthetic history-taking with reference to patients' prior anesthetic experiences.

Anesthesia, Intravenous↗