Biomedical subjects

T A Leighton

Publications and source records attributed to T A Leighton.

5 recordsLinked to original sources

PubMed1993

Helium insufflation for laparoscopic operation.

Laparoscopic surgical procedures are becoming simultaneously more commonplace and complex. However, carbon dioxide (CO2) pneumoperitoneum required for these procedures causes a respiratory acidosis. We undertook this study to determine if an alternate insufflating gas, such as helium, prevents this sequelae. Twenty patients undergoing elective laparoscopic cholecystectomy were randomized to receive either CO2 or helium insufflation. Intraoperative parameters, including arterial CO2 (PaCO2), end-tidal CO2, pH, bicarbonate (HCO3-), cardiac output and blood pressure were obtained before, during and at the conclusion of pneumoperitoneum. Effects of the two gases on these variables were compared. The average CO2 rose significantly from 35.7 +/- 1.0 to 50.4 +/- 3.2 (p < 0.0001), while pH decreased from 7.434 +/- 0.014 to 7.286 +/- 0.018 (p < 0.0001) in those who received CO2. No change in PaCO2 was observed in those who received He, although a small decrease in pH from 7.428 +/- 0.011 to 7.392 +/- 0.012 (p < 0.05) was observed. HCO3- decreased slightly in both groups. Increases in blood pressure and pulse rate were independent of the gas received. The cardiac output did not change. Helium insufflation for laparoscopic cholecystectomy does not produce the respiratory acidosis caused by CO2 and, therefore, merits further investigation for use, particularly in patients with underlying respiratory disease.

Adult↗

PubMed1993

Comparative cardiopulmonary effects of carbon dioxide versus helium pneumoperitoneum.

The recent surge in enthusiasm for laparoscopic surgery has created concern that abdominal insufflation with carbon dioxide produces a respiratory acidosis. This may be because of both transperitoneal gas absorption and impaired ventilation with increased dead space from elevated intraabdominal pressure. To examine the relative contributions of these factors, we developed an animal model of surgical pneumoperitoneum that evaluated the cardiorespiratory effects of abdominal insufflation. Helium was chosen as an alternative to CO2 because it is both chemically and biologically inert. Carbon dioxide absorption during CO2 pneumoperitoneum caused arterial PCO2 to increase from 41.3 +/- 3.0 to a maximum of 58.3 +/- 4.0 mm Hg, with pH descending from 7.46 +/- 0.02 to a nadir of 7.31 +/- 0.02 (p < 0.05). Pulmonary artery pressure increased to twice baseline levels during CO2 insufflation (p < 0.05). Helium did not cause hypercarbia, acidemia, or pulmonary hypertension despite insufflation under identical conditions. These results indicate that transperitoneal absorption of CO2, not increased dead space, is responsible for the respiratory acidosis observed. Helium merits further study as an agent to induce pneumoperitoneum, especially when concerns of underlying acidosis or impaired gas exchange are present.

Acidosis, Respiratory↗

PubMed1992

Continuous dual oximetry in surgical critical care. Indications and limitations.

Continuous dual oximetry combines pulse and venous oximetry to provide real-time information about oxygen utilization and pulmonary function. The authors undertook this study to examine the accuracy, utility, and limitations of the technique in surgical critical care. Twelve critically ill patients underwent placement of a modified pulmonary artery catheter and a pulse oximeter, both connected to an on-line computer. Paired blood gas and oximeter measurements were recorded every 4 to 6 hours, with a minimum of six sets per patient. Blood-gas-derived shunt fraction correlated well with oximeter-derived ventilation-perfusion index (r = 0.78, p less than 0.01). Further, the continuous oxygen extraction ratio (O2EI) and mixed venous oxygen saturation (SpvO2) correlated with the oxygen utilization coefficient (O2EI:r = 0.6, p less than 0.01; SpvO2, r = 0.76, p less than 0.01). Computer modeling of ventilation-perfusion index found limitations in accuracy that occur at high arterial oxygen saturations and when pulse oximetry errors are present. The authors conclude that (1) Continuous dual oximetry offers a significant advantage over routine blood gas analysis for monitoring cardiopulmonary parameters in critically ill patients because of its real-time display; (2) Oximeter-derived determinations parallel traditional parameters; and (3) The most significant technical limitations occur primarily at high arterial saturations and with pulse oximetry errors.

Adolescent↗

PubMed1991

Time-course of cardiopulmonary effects tumor necrosis factor and endotoxin are similar.

Tumor necrosis factor (TNF) is a postulated proximal septic mediator. The authors compared the time course and extent of the cardiopulmonary effects of recombinant human TNF (rTNF) in swine vs those of Escherichia coli endotoxin (ETX). Intravenous boluses of either rTNF (n = 4), ETX (n = 2), or saline (n = 4) were given to swine. Mean pulmonary artery pressure and extravascular lung water (EVLW) were increased at 60 minutes for rTNF and ETX to 31 +/- 2 mmHg and 33 +/- 3 mmHg and 6.3 +/- 0.9 ml/kg and 7.1 +/- 1.6 ml/kg, while saline animals were unchanged. The authors conclude that rTNF mimics ETX both in time course and magnitude of effects. Right-sided cardiopulmonary effects predominate in both with minimal left-sided effects at these dosages. The time course of early increased EVLW suggests an initial hydrostatic influence on pulmonary edema formation in this septic model.

Animals↗

PubMed1991

Peripheral arterial shotgun missile emboli: diagnostic and therapeutic management--case reports.

Arterial bullet embolism is an uncommon complication of vascular trauma. While many reports exist of peripheral embolism from aortic entry sites, few cases are described of distal embolization from peripheral arteries. Untreated emboli may cause ischemia and threaten the limb at a site far removed from the point of missile entry. Unless suspected, diagnosed, and extracted, these emboli may ultimately result in limb loss in spite of a successful proximal arterial repair. During the last 10 years we treated 4 such cases, all of whom had initial limb salvage. This report describes our diagnostic and operative management of these injuries and collectively summarizes our experience as well as all other cases in the literature.

Adolescent↗