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Biomedical subjects

John G Brock-Utne

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

At least 19 recordsLinked to original sources

Esophageal saturation during antegrade cerebral perfusion: a preliminary report using visible light spectroscopy.

BACKGROUND: Visible light spectroscopy (VLS) is newer technology that measures real-time tissue oxygenation. It has been validated in detecting mucosal ischemia in adults. During complex neonatal heart surgery, antegrade cerebral perfusion (ACP) maintains cerebral saturation. Whether ACP maintains peripheral tissue perfusion in humans is not known. METHODS: Five patients undergoing neonatal open heart surgery with hypothermic cardiopulmonary bypass (CPB) were studied using a VLS esophageal probe in addition to bilateral near infrared cerebral oximetry. Three of five patients required ACP for arch repair, while two patients did not. VLS and cerebral saturation data were collected and analyzed in 5 min intervals prior to CPB, during CPB, and during ACP. RESULTS: In the two patients undergoing heart surgery with routine hypothermic CPB, both cerebral and esophageal saturations were maintained. However in all three neonates requiring ACP, although cerebral saturations did not decrease, esophageal saturation fell below the ischemic threshold (35%). Following establishment of normal CPB, esophageal saturation returned to baseline. CONCLUSIONS: Antegrade cerebral perfusion maintains cerebral oxygen delivery, however, it does not adequately perfuse the esophagus in neonates. This could have clinical implications.

Brain Ischemia↗

General anesthesia and chronic amphetamine use: should the drug be stopped preoperatively?

Prescription amphetamines are being used more often for several medical conditions. Anesthesia concerns focus on the cardiovascular stability of patients who may be catecholamine-depleted and thus have a blunted response to intraoperative hypotension. Previously we reported one case of a patient receiving chronic amphetamine therapy who had a stable intraoperative course. We now report eight additional patients taking chronic prescription amphetamines who underwent a safe general anesthesia and outcome. Predominantly prescribed for narcolepsy and attention deficit hyperactivity disorder, amphetamine drugs had been given to these 8 patients for 2 to 10 yr. Ages ranged from 22 to 77 yr and genders were equally divided. All required general anesthesia for their surgical procedures and 6 of the 8 patients were tracheally intubated. Anesthesia operating room times ranged from 30 min to 4.25 h. The authors conclude that amphetamine use need not be stopped before surgery and anesthesia.

Adult↗

Intra-operative fluid volume influences postoperative nausea and vomiting after laparoscopic gastric bypass surgery.

BACKGROUND: Laparoscopic Roux-en-Y gastric bypass (RYGBP) is a commonly performed operation for morbid obesity. A significant number of patients experience postoperative nausea and vomiting (PONV) following this procedure. The aim of this study was to determine the effect, if any, of intra-operative fluid replacement on PONV. METHODS: Patients who underwent laparoscopic (RYGBP) for morbid obesity during a 12-month period were included in this retrospective analysis. Demographic data including age, gender, and body mass index (BMI) were collected. Perioperative data also included total volume of intra-operative fluids administered, rate of administration, urine output, length of surgery, and incidence of PONV as determined by nursing or anesthesia records in the postanesthesia care unit (PACU). Data were analyzed by t-test. RESULTS: The table below depicts demographic and perioperative data, comparing patients who experienced PONV (n=125) in the PACU with those who did not (n=55). Values are mean +/- standard deviation. CONCLUSIONS: PONV is a common complication after laparoscopic RYGB. Patient who did not experience PONV received a larger volume of intravenous fluid at a faster rate than similar patients who complained of PONV.

Adult↗

Wrist hyperextension leads to median nerve conduction block: implications for intra-arterial catheter placement.

BACKGROUND: It is common practice to hyperextend the wrist to facilitate insertion of a radial intra-arterial catheter. This position may be maintained for prolonged periods. Although there has been much discussion about optimal patient management to protect the ulnar nerve and brachial plexus, little attention has been paid to the median nerve during wrist hyperextension. The authors report the effects of wrist hyperextension on conduction in the median nerve. METHODS: Median nerve conduction was studied in 12 awake, healthy volunteers using standard nerve conduction tests consisting of the measurement of compound sensory and motor action potentials, as well as their amplitudes and latencies. With the contralateral hand as a control, the right wrist was placed in hyperextension (angled between 65 and 80 degrees), and compound action potentials were recorded to determine the onset and magnitude of effects. Subsequently, the hand was released from hyperextension and recovery was recorded. RESULTS: In 83% of subjects, hyperextension resulted in a significant decrease in compound sensory action potential amplitudes, sufficient to qualify as conduction block (16.6% of baseline). The average time to conduction block was 43 +/- 13.2 min. All subjects who manifested conduction block showed marked improvement 5 min after release from hyperextension. CONCLUSIONS: Wrist hyperextension for arterial line placement and stabilization is likely to result in profound impairment of median nerve function. Although the effects were transient in this study, the results suggest that prolonged hyperextension may be associated with significant changes in median nerve conduction. To minimize the chance for nerve injury, the authors recommend that wrists be returned promptly to the neutral position following arterial line placement.

Action Potentials↗

Heat and moisture exchange devices: are they doing what they are supposed to do?

UNLABELLED: Heat and moisture exchangers (HMEs) are used to provide humidification and warming of the inspiratory gases during general anesthesia. The performance specifications provided by manufacturers of HMEs are based on in vitro measurements of moisture output using the International Standards Organization (ISO) 9360 method. We studied the in vivo performance of three different HMEs with similar ISO specifications in a randomized crossover fashion in patients under general anesthesia. The effect of each HME on temperature, convective heat loss, evaporative heat loss, total heat loss, relative humidity, and absolute humidity of inspiratory gases was determined. Although all HMEs in general improved baseline variables, we found significant differences in performance for the different HMEs. In only one type did the moisture output correspond with ISO specifications. We conclude that the in vivo performance of HMEs may not correspond with manufacturer's specifications. IMPLICATIONS: There is considerable variability in the in vivo performance of heat and moisture exchangers that have similar manufacturer specifications. These specifications, based on the International Standards Organization 9360 standard, which is measured in vitro, cannot be used to predict clinical performance.

Absorption↗

Anesthetic concerns for robot-assisted laparoscopy in an infant.

A 2-mo-old infant with biliary atresia was scheduled for laparoscopic Kasai with robot assistance. Before surgery, a practice trial maneuvering the cumbersome robotic equipment was performed to ensure rapid access to the patient in case of emergency. IV access, tracheal intubation, and arterial line placement followed inhaled anesthesia induction with sevoflurane. Robotic setup took 53 min and severely limited patient access. No adverse events occurred during the procedure requiring the removal of the robotic equipment, and the patient was discharged after a stable postoperative recovery. Advance preparation is required to maximize patient safety during robotic surgery.

Anesthesia, Inhalation↗

Laryngoscopy and morbid obesity: a comparison of the "sniff" and "ramped" positions.

BACKGROUND: The effect of patient position on the view obtained during laryngoscopy was investigated. METHODS: 60 morbidly obese patients undergoing elective bariatric were studied. Patients were randomly assigned into one of two groups. In Group 1, a conventional "sniff" position was obtained by placing a firm 7-cm cushion underneath the patient's head, thus raising the occiput a standard distance from the operating-table while the patient remained supine. In Group 2, a "ramped" position was achieved by arranging blankets underneath the patient's upper body and head until horizontal alignment was achieved between the external auditory meatus and the sternal notch. Following induction of general anesthesia, tracheal intubation was performed using a Video MacIntosh laryngoscope. The laryngoscopy and intubation sequences were recorded onto videotape. Three independent investigators, unaware as to which position the patient had been in at the time of tracheal intubation, then viewed the videotape and assigned a numerical grade to the best laryngeal view obtained. RESULTS: The "ramped" position improved the laryngeal view when compared to a standard "sniff" position, and this difference was statistically significant (P=0.037). CONCLUSION: The "ramped" position is superior to the standard "sniff" position for direct laryngoscopy in morbidly obese patients.

Adult↗

The timing of electroconvulsive therapy and bispectral index after anesthesia induction using different drugs does not affect seizure duration.

STUDY OBJECTIVE: To determine the association between bispectral index (BIS) and seizure duration obtained by electroconvulsive therapy (ECT) administered sooner or later after anesthetic induction. DESIGN: Prospective, randomized, crossover study. SETTING: University-affiliated medical center. PATIENTS: Nine ASA physical status I, II, and III patients undergoing a total of 31 ECTs. INTERVENTIONS: ECT was administered soon (<210 sec) or later (between 210 sec and 360 sec) after anesthetic induction. In each individual patient, drug regimens and ECT machine settings were identical. MEASUREMENTS: BIS immediately before the start of the ECT and the duration of the EEG seizure were recorded, as well as the time period between loss of consciousness and ECT administration. MAIN RESULTS: There was no relationship between BIS level and seizure duration. Moreover, seizure duration was not dependent on the time of ECT administration in the time window between one and 6 minutes after loss of consciousness. CONCLUSION: The hypnotic drug effect measured by the BIS is not correlated to the seizure duration obtained by ECT.

Aged↗

Airway complication following functional endoscopic sinus surgery.

Difficulty breathing after upper airway surgery requires immediate evaluation and treatment. We present a case of airway compromise after sinus surgery due to edema of the uvula. The patient was admitted for observation overnight and discharged the next day. A discussion of potential airway changes after sinonasal surgery is presented.

Adult↗