Biomedical subjects

S T Sum Ping

Publications and source records attributed to S T Sum Ping.

4 recordsLinked to original sources

PubMed1992

Accuracy of the FEF CO2 detector in the assessment of endotracheal tube placement.

The sensitivity and reliability of the FEF end-tidal CO2 detector were investigated for its suitability in the assessment of correct placement of an endotracheal tube. Sensitivity was determined by having eight blinded volunteers observe the color change in the FEF detector with the administration of different volumes and varying CO2 concentrations of gas mixture. The color change in the FEF detector was also assessed during esophageal ventilations before and after administration of carbonated beverage into the stomach of swine and during cardiopulmonary resuscitation in swine. An interpersonal variation was present among the blinded observers during the color-matching process. Different colors were observed with the same volume and CO2 concentration of gas mixture. During esophageal ventilations before or after the administration of carbonated beverage, the FEF detector was neither accurate nor rapid in identifying esophageal placement of the endotracheal tube. The "C" color was displayed during the initial six ventilations in one swine, and esophageal intubation would have been missed. The FEF detector could (by displaying a "C" color) identify one of six correctly intubated swine during cardiopulmonary resuscitation. In conclusion, the FEF CO2 detector does not have the characteristics to reliably assess the correct placement of an endotracheal tube.

Animals↗

PubMed1991

Human learning during general anaesthesia and surgery.

To determine if learning occurs during general anaesthesia, 72 women undergoing surgery were given postoperative implicit memory tests in which performance could be influenced by auditory information presented during general anaesthesia. Two methods of anaesthesia were used: nitrous oxide and opioids (n = 24) or nitrous oxide and isoflurane (1, 1.3 and 1.5 MAC for n = 12, 24 and 12, respectively). Three tests showed some retention, apparently unconscious, of information presented during anaesthesia: in Behavioural Suggestions tests, patients who were instructed during anaesthesia to touch a particular body part (ear or nose) during later questioning touched the "correct" (suggested) body part longer than the "incorrect" (not suggested) body part during a postoperative interview on the day of surgery (means 2.5 vs 0.2 s); in World Completion tests, patients shown a page containing the first three letters of words and asked to give words beginning with those letters gave more words from a list that had been played during anaesthesia than from a list not played (means 0.48 vs 0.27 words); in Nonsense Word tests, patients who were played different nonsense words between two and 16 times during anaesthesia preferred and guessed more accurately those that had been played most often (16 times) relative to those played less often in subsequent preference and recognition tests (means 56% vs 46% for preference and 62% vs 48% for recognition), while showing no such patterns in additional control tests. Learning did not vary with the method of anaesthesia, as might have been expected if learning was a monotonic function of brain depression. Some information processing functions of the brain evidently continue to function during adequate general anaesthesia.

Adult↗

PubMed1991

Efficacy of therapeutic suggestions for improved postoperative recovery presented during general anesthesia.

There have been claims that the postoperative course of patients may be improved by presentation during general anesthesia of therapeutic suggestions which predict a rapid and comfortable postoperative recovery. This study evaluated the effectiveness of such therapeutic suggestions under double-blind and randomized conditions. A tape recording predicting a smooth recovery during a short postoperative stay without pain, nausea, or vomiting was played during anesthesia to about half the patients (N = 109), while the remaining, control patients were played a blank tape instead (N = 100). The patients were primarily undergoing operations on the fallopian tubes, total abdominal hysterectomy, vertical banding gastroplasty, cholecystectomy, and ovarian cystectomy or myomectomy. The anesthesia methods consisted of either isoflurane with 70% nitrous oxide in oxygen to produce end-tidal concentrations of 1.0, 1.3, or 1.5 MAC; or 70% nitrous oxide in oxygen combined with high or low doses of opioids. Assessments of the efficacy of the therapeutic suggestions in the recovery room and throughout the postoperative hospital stay included: the frequency of administration of analgesic and antiemetic drugs; opioid doses; the incidence of fever; nausea, retching, and vomiting; other gastrointestinal and urinary symptoms; ratings of pain; ratings of anxiety; global ratings of the patients' physical and psychological recoveries by the patients and their nurses; and length of postoperative hospital stay. There were no meaningful, significant differences in postoperative recovery of patients receiving therapeutic suggestions and controls. These negative results were not likely to be due to insensitivity of the assessments of recovery, as they showed meaningful interrelations among themselves and numerous differences in recovery following different types of surgery. Widespread utilization of therapeutic suggestions as a routine operating room procedure seems premature in the absence of adequate replication of previously published positive studies.

Adult↗

PubMed1991

Reliability of capnography in identifying esophageal intubation with carbonated beverage or antacid in the stomach.

To evaluate the reliability of capnography in identifying esophageal intubation in the presence of a carbonated beverage in the stomach, we first investigated the amount of CO2 released from different carbonated beverages and antacids in a simulated stomach; next we measured the end-expired CO2 level during esophageal ventilation with a carbonated beverage in the stomachs of six swine. CO2 levels of approximately 20% were consistently observed in all carbonated beverages. The CO2 levels obtained with sodium bicarbonate, Maalox, and sodium citrate were 19.3%, 2.0%, and 0%, respectively. CO2 waveforms were observed during esophageal ventilation in five of six animals after intragastric administration of a carbonated beverage. An end-expired CO2 level of 2.5% or more was observed in two swine. The highest end-expired CO2 level measured was 5.3%. We conclude that although capnography is convenient and effective, it lacks all the attributes of an ideal monitor for detecting esophageal intubation.

Animals↗