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Biomedical subjects

J F Hardy

Publications and source records attributed to J F Hardy.

68 records · Page 4Linked to original sources
PubMed1987

Determining gastric contents during general anaesthesia: evaluation of two methods.

Two methods used to measure the volume of gastric contents were evaluated in 24 supine anaesthetized adults. Methods compared were: (1) aspiration of stomach contents through a large, vented, multi-orificed gastric tube, and (2) indirect determination by a dye dilution method using polyethylene glycol (PEG) as the marker. The volumes determined by these methods (Vasp and Vpeg respectively) were compared to the total volume (Vtot) present in the stomach, determined by direct inspection of the gastric pouch by the surgeon at the beginning of surgery. The results show that the volume of aspirated gastric fluid, using this type of tube, is a very good estimate of the total volume of gastric residue. The PEG dilution method yields similar results. However, correlation between Vpeg and Vtot was not as close-fitting as the correlation between Vasp and Vtot. PEG dilution is more complicated, time-consuming and offers no advantage over aspiration.

Anesthesia, General↗
PubMed1986

Aspiration pneumonia: assessing the risk of regurgitation in the cat.

Depending on the population characteristics, 12 to 80 per cent of patients undergoing elective surgery exceed the current risk criteria for aspiration pneumonitis (gastric volume greater than or equal to 0.4 ml.kg-1 and pH less than or equal to 2.5), in sharp contrast to the actual incidence of the disorder, estimated at 0.01 per cent. Improved specificity would likely result if the risk of regurgitation was also considered, in addition to the volume and pH criteria. As a first attempt to assess the risk of regurgitation under general anaesthesia, we measured the minimal gastric volume (VR) required to produce regurgitation in cats anaesthetized with ketamine. The mean was 20.8 ml.kg-1 (n = 7, range: 8-41, SD = 7.8). We conclude that the residual gastric volume needed to produce a regurgitation under general anaesthesia is at least 20 times greater than the volume required to produce pulmonary damage by intratracheal injection (0.3 ml.kg-1, assuming a pH of 2.5 or less).

Anesthesia, General↗
PubMed1986

Nausea and vomiting after strabismus surgery in preschool children.

The incidence of nausea and vomiting after strabismus surgery was studied in 64 children aged one to six years. Incidence was determined in the post-anaesthesia recovery room (PARR), in the same day surgery (SDS) unit, and at home on days one and two after the operation. After induction of anaesthesia, the children received an intravenous injection of droperidol (50 micrograms . kg-1) or saline in a double-blind randomized fashion, and an intravenous injection of glycopyrrolate (7.5 micrograms . kg-1) or atropine (10 micrograms . kg-1) in an open randomized fashion. The incidence of emetic symptoms was highest in the SDS unit and at home on day one. Droperidol slightly but significantly delayed awakening and was not, at least in this particular age group, associated with any difference in postoperative sickness. Despite theoretical advantages, glycopyrrolate offered no significant benefit over atropine as far as postoperative emesis was concerned.

Anesthesia, General↗
PubMed1983

The oculocardiac reflex: a graphic and statistical analysis in infants and children.

A new method for the detection and recording of the oculocardiac reflex (OCR) is described and applied to 49 healthy infants and children (six months to nine years old) undergoing strabismus surgery under halothane anaesthesia with spontaneous ventilation. Eighty-one extraocular muscles were studied. Square wave stimuli (abrupt and sustained tractions) were definitely more reflexogenic than slow slope stimuli (very gradual, progressive and gentle tractions). Vagal escape, as well as fatigue of the OCR, are graphically documented and analysed. In this series, using well-defined and controlled tractions, the medial rectus was not more reflexogenic than the other extraocular muscles. Hypercapnia was an important adjuvant factor of the OCR. Controlled ventilation is recommended. The routine use of intravenous anticholinergic drugs is briefly discussed. Prevention of the OCR, and prophylaxis of cardiac arrhythmias during strabismus surgery, now seem to be placed on a more rational basis.

Age Factors↗
PubMed1983

Pathophysiology of rupture of the pulmonary artery by pulmonary artery balloon-tipped catheters.

High pressures have been reported in pulmonary artery catheter balloons. This study was undertaken to determine the in vitro rupturing pressures of human peripheral pulmonary arteries and to evaluate whether such pressures could be generated under clinical conditions. The in vitro model then was confirmed in vivo in the dog and the evolution of a rupture of a peripheral pulmonary artery studied. In vitro, pulmonary arteries of subjects under age 60 yr are remarkably resistant and tolerate intra-balloon pressures of 2700 mm Hg in the one mid-pulmonary artery studied and up to 4219 +/- 720 mm Hg (mean +/- SD) in the distal pulmonary artery. Subjects over the age of 60 yr have significantly lower rupturing pressures (1965 +/- 540 mm Hg in the mid-pulmonary artery, and 2498 +/- 600 mm Hg in the distal pulmonary artery), (P less than 0.05). Thus overdistension by the balloon may explain most ruptures. Preexisting pulmonary hypertension did not affect in vitro rupturing pressures. Clinicians generated intraballoon mean pressures of 795 +/- 130 mm Hg, with 20% of them generating higher and potentially dangerous pressures (1000 mm Hg or more). The in vitro model was confirmed by in vivo studies in dogs with pressures that cause pulmonary artery rupture. Furthermore, in normal dogs, rupture of a peripheral pulmonary artery was without complications. This suggests that rupture of the peripheral pulmonary artery may occur clinically more frequently than reported. The user of flotation pulmonary arterial catheters should be aware of the dangers associated with this diagnostic tool. In particular, liquids must never be used to inflate pulmonary arterial catheter balloons.

Air Pressure↗
PubMed1983

The oculocardiac reflex in strabismus surgery.

During strabismus surgery on 81 extraocular muscles in 49 children the cardiac response to calibrated traction on each of the muscles operated on was studied through the use of a microdisplacement transducer and the tachometer of a cardiac monitor. There was no significant difference in the frequency of induction of the oculocardiac reflex between the medial rectus and the other muscles or between the two eyes. However, quick traction provoked a reflex in 87% of instances, whereas progressive traction did so in only 51% of instances, a significant difference (p less than 0.05). Thus, because the oculocardiac reflex is frequent during strabismus surgery, cardiac monitoring during the operation and minimal, gentle manipulation of the extraocular muscles are important.

Child↗
PubMedDate not supplied

Randomized, placebo-controlled, double-blind study of an ultra-low-dose aprotinin regimen in reoperative and/or complex cardiac operations.

BACKGROUND AND AIM OF THE STUDY: High-dose aprotinin is an effective but costly method to reduce transfusions after cardiopulmonary bypass (CPB). Very low doses of aprotinin have been shown to be effective in primary cardiac surgery, but not in patients undergoing procedures associated with the greatest usage of allogeneic blood products after CPB. We evaluated the efficacy of ultra-low-dose aprotinin in this patient population. METHODS: Aprotinin 1 million KIU or placebo was added to the priming solution of the CPB circuit of 52 patients undergoing a reoperation and/or a complex surgical procedure. Dryness of operative field, hemoglobin concentrations, coagulation parameters, chest drainage, and transfusion requirements were compared. RESULTS: Total chest drainage was not different between groups, but fewer patients in the aprotinin group required additional protamine postoperatively (35% vs 69% for controls, p = 0.03) and fewer received fresh frozen plasma (FFP; 19% vs 46% for controls, p = 0.04). Red cell transfusion was smaller in the aprotinin group compared to placebo (median 4 and 2 units, respectively, p = 0.04). Transfusion of FFP, platelets, cryoprecipitates was not different between groups. Total number of units transfused tended to be reduced in the aprotinin group compared to control (median 2 and 7 units, respectively, p = 0.06). CONCLUSIONS: Prophylactic administration of ultra-low-dose aprotinin reduced transfusions in patients undergoing repeat operations or complex procedures. Aprotinin could be used in a more economical manner, even in this patient population at high-risk of receiving allogeneic blood products.

Aged↗