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Biomedical subjects

J G Brock-Utne

Publications and source records attributed to J G Brock-Utne.

At least 19 recordsLinked to original sources
PubMed1995

Is nitrous oxide safe for bone marrow harvest?

Patients with non-Hodgkins lymphoma undergoing autologous bone marrow harvest were studied in a prospective, randomized fashion. All patients received a general anesthetic consisting of intravenous thiopental, fentanyl, and vecuronium and were ventilated with oxygen and isoflurane. Group I (19) patients also were ventilated with nitrous oxide (70%) whereas patients in Group II (19) did not receive nitrous oxide. Bone marrow samples were obtained at the beginning and end of the harvest. Viability of bone marrow mononuclear cells was assessed with a colony-forming unit-granulocyte macrophage (CFU-GM) assay, CFU-GM growth is a marker for myeloid progenitor cells and is dependent on intact deoxyribonucleic acid synthesis. Rate of neutrophil engraftment after autologous bone marrow transplantation was also studied. Both groups of patients were statistically similar in age, weight, anesthetic duration, CFU-GM counts at both sample draws, and the time for successful engraftment. There appears to be no difference in bone marrow viability as assayed by both CFU-GM colony growth and engraftment in human bone marrow exposed to a general anesthetic with nitrous oxide.

Adult↗
PubMed1995

A cost analysis of the laryngeal mask airway for elective surgery in adult outpatients.

BACKGROUND: Since the introduction of the laryngeal mask airway (LMA) into the United States in 1991, the device has become widely used in anesthesia practice. The purpose of this economic analysis was to use existing data to evaluate the costs of the LMA relative to three other common airway management techniques and to identify the variables that had the greatest effect on cost efficiency. METHODS: We evaluated four airway management techniques for healthy adults receiving an isoflurane-nitrous oxide-oxygen anesthetic for elective outpatient surgery: (1) LMA with spontaneous ventilation; (2) face mask with spontaneous ventilation; (3) tracheal intubation after succinylcholine with subsequent spontaneous ventilation; and (4) tracheal intubation after nondepolarizing neuromuscular blockade and controlled ventilation. We analyzed published clinical studies of the LMA and obtained cost data from Stanford University Medical Center. The best available estimates of the independent variables were incorporated into a baseline case. For each airway technique we derived cost equations that excluded costs common to all four techniques. RESULTS: Relative to airway management with an LMA, calculated values for the baseline analysis included additional isoflurane costs for use of a face mask ($ 0.12/min) and for tracheal intubation with ($ 0.043/min) and without neuromuscular blockade ($ 0.06/min). With a neuromuscular blocking drug cost of $ 0.21/min and an LMA cost per use of $ 20, the face mask with spontaneous ventilation was the cost-efficient airway choice for anesthetics lasting as long as 100 min. Increasing the LMA reuse rate from 10 to 25 made the LMA the least costly airway technique for cases lasting more than 70 min. CONCLUSIONS: If the LMA is reused 40 times, the LMA is the cost-efficient airway choice for outpatients receiving an isoflurane-nitrous oxide-oxygen anesthetic lasting longer than 40 min. This finding does not change if the cost of neuromuscular blockade or the incidence of airway-related complications is varied over a clinically relevant range.

Adult↗
PubMed1992

Difficulty in extubation. A cause for concern.

Difficulties in removing the tracheal tube from the trachea are relatively uncommon. We report here a case of difficult extubation which was precipitated by pulling off the pilot balloon and valve assembly in order to deflate the cuff.

Adult↗
PubMed1992

Are electrocardiogram changes the first sign of impending peri-operative pneumothorax?

A patient in the right lateral position underwent left nephrectomy, after which he was placed supine for insertion of an arteriovenous fistula. All haemodynamic and respiratory values, including peak inspiratory pressure, were within normal limits and unchanged from baseline measurements. However, following the position change we noted that the amplitude of the electrocardiogram complexes were dramatically reduced. Our differential diagnosis included the possibility of a pneumothorax, which was subsequently confirmed by both physical examination and chest X ray. A chest drain was planned to be inserted at the end of the surgery, but 25 min after the electrocardiogram changes were noted, the patient's vital signs suddenly deteriorated. Emergency treatment for pneumothorax was instituted with good effect. The diagnostic use of the electrocardiogram and the treatment of this intra-operative pneumothorax are discussed.

Drainage↗
PubMed1992

Aspects of mechanical ventilation affecting interatrial shunt flow during general anesthesia.

Intraoperative transesophageal echocardiography was used to study the incidence of flow-patent foramen ovale in 33 normal, healthy patients (ASA physical status I) undergoing general anesthesia in the supine position for nonthoracic surgical procedures. Echocardiographic contrast was injected intravenously during mechanical ventilation in the presence of 0, 5, 10, 15, or 19 cm H2O positive end-expiratory pressure (PEEP). A final test was performed during the release of 19 cm H2O PEEP. The presence of a flow-patent foramen ovale was detected when the injected echo targets were observed crossing the interatrial septum from right to left. Most interesting, 3 of 33 patients developed a right-to-left shunt that was first detected with the steady application of 10 (1 patient) or 15 cm H2O PEEP (2 patients). In all three cases, the shunt flow was accentuated on the release of PEEP; however, no additional cases were detected using this respiratory maneuver. These cases represent the first demonstration of right-to-left interatrial shunting evoked as the result of the sustained application of PEEP. This study also revealed a lower than expected incidence of flow-patent foramen ovale (9%) when measured during general anesthesia and positive pressure ventilation with or without PEEP.

Adult↗
PubMed1992

Anesthesia in military conflicts: towards simpler, safer, and higher standards.

The increasing military activity in the Persian Gulf necessitates that anesthesiologists in the United States should gain familiarity with the use of a draw-over vaporizer attached to a non-rebreathing circuit. Unfortunately, distributors of draw-over vaporizers in the United States do not allow anesthetists to use this equipment on humans in North America when conventional anesthesia equipment is available. Since the standard of anesthesia care in the U.S. is high, the use of a draw-over vaporizer is not allowed in most settings. Hence, this article reviews the function, the advantages, and disadvantages of a draw-over vaporizer attached to a non-rebreathing circuit. The use of an oxygen concentrator is also discussed, which increases the safety of this anesthetic delivery system.

Anesthesiology↗
PubMed1991

Oxygen pipeline supply failure: a coping strategy.

Oxygen is the most vital drug administered during anesthesia. The delivery of hypoxic or even anoxic gas mixtures during anesthesia has been reported. Because such occurrences often meet with disaster, modern anesthesia machines have a system of alarms to warn against the delivery of hypoxic or anoxic gas mixtures and also to warn of the failure of the oxygen pipeline supply. We describe the occurrence of a sudden failure of the oxygen pipeline supply, and discuss a strategy for coping with this emergency.

Adult↗
PubMed1991

The effect of tourniquet release on intra-compartmental pressure in the bandaged and unbandaged limb.

Changes in intra-compartmental pressure in bandaged and unbandaged limbs following 90 minutes of tourniquet-induced ischaemia and subsequent tourniquet release are examined in a primate model. Bandaging raises intra-compartmental pressure. Release of the tourniquet is shown to cause a transient increase in intra-compartmental pressure of less than 30 minutes duration. This is followed by a fall in intra-compartmental pressure for up to three hours. Tourniquet release and the ensuing hyperaemia does not appear to put the limb at risk of developing a compartment syndrome.

Animals↗
PubMed1991

Use of an oxygen concentrator linked to a draw-over vaporizer (anesthesia delivery system for underdeveloped nations)

The use of an oxygen concentrator linked to a draw-over vaporizer was examined. The fractional oxygen concentration from this equipment was dependent on the minute ventilation, oxygen output of the concentrator (%), and the presence of an oxygen economizer tube (OET) (a 900-mL corrugated tube). Fractional oxygen concentrations were always higher with an OET than without an OET (other variables being constant). With the OET in place, the fractional oxygen concentration was only dependent on the minute volume and independent of the pattern of ventilation (i.e., varying inspiratory and expiratory ratios and inspiratory and expiratory pauses). Without an OET, the performance of the system was considerably impaired. In this setting, the final oxygen concentration depended not only on the added flow of oxygen and minute volume but also on the pattern of ventilation. In conclusion, when using a draw-over vaporizer linked to an oxygen concentrator, an OET is essential so as to provide consistent oxygen concentrations to the patient at any given minute volume.

Anesthesiology↗