Depression of plasma levels of cytokines and ex-vivo cytokine production in relation to the activity of the pituitary-adrenal axis, in patients undergoing major vascular surgery

The relation between the immune and neuroendocrine response during surgery was studied. In 18 patients undergoing major vascular surgery, circulating interleukin (IL)-1beta and ex-vivo production of IL-1beta and tumour necrosis factor (TNF)-alpha were lower on day 1 after surgery compared to pre-operation values (-14+/-5%, P<0.05; -62+/-9%, P<0.05; and -31+/-54%, P<0.005, respectively). Circulating IL-1 receptor antagonist (IL-1ra) was higher on the 5th day post-operatively compared to pre-operation values (mean +640%+/-400, P<0.05). In a more detailed study in six patients, the ex-vivo production of IL-1beta and TNF-alpha started to decrease at induction of general anaesthesia and dropped to under 10% of initial values at the end of surgery. Circulating IL-1ra and ex-vivo production of IL-1ra started to increase at the end of surgery and remained elevated up to 6 days post-operatively. Plasma antidiuretic hormone (ADH) and adrenocorticotropic hormone (ACTH) increased during surgery, but cortisol remained unchanged. We demonstrate a depression of circulating pro-inflammatory IL-1beta and an increase of circulating anti-inflammatory IL-1ra during surgical stress. The ex-vivo production of IL-1beta and TNF-alpha was suppressed, indicating a downregulation of the production of these cytokines. This parallelled the hormonal reaction with high ADH and ACTH, but not of cortisol, suggesting that glucocorticoid is not the key-factor in downregulation of production and release of pro-inflammatory cytokines.

Does peritoneal mobilization increase laparoscopic acidosis?

PURPOSE

It was hypothesized that laparoscopic colon surgery may be associated with increased absorption of CO2 resulting from mobilization of lateral peritoneal reflections.

METHODS

Six pigs underwent laparotomy with removal of a measured quadrant of peritoneum before insufflation to 15 mmHg with CO2. Six paired control animals also underwent insufflation with CO2 to 15 mmHg. Measurements of the end-tidal CO2 (PetCO2), arterial blood gas analysis for CO2 (PaCO2), and pH were performed before insufflation, at 5 and 10 minutes following insufflation, then at successive 15-minute intervals for a total of two hours, and 15 minutes following desufflation. No attempt was made to correct the hypercarbia by increasing minute ventilation.

RESULTS

PaCO2 reached its maximum level at two hours with values of 70.77 +/- 5.54 mmHg and 64.62 +/- 5.18 mmHg in the peritonectomized and control groups, respectively. PetCO2 also peaked at two hours to 60 +/- 13 mmHg for the study group and 54 +/- 11 mmHg for controls. pH reached its nadir at two hours, falling from a baseline of 7.45 +/- 0.08 to 7.23 +/- 0.09 in the study group, and from 7.42 +/- 0.04 to 7.24 +/- 0.04 in the control group. There were no statistically significant differences between the two groups for any of the parameters measured at each time interval.

CONCLUSIONS

The hypothesis that peritonectomy produces greater CO2 absorption during CO2 pneumoperitoneum was disproved under these experimental conditions.

Diagnosis and treatment of respiratory symptoms of initially unsuspected gastroesophageal reflux in infants

Gastroesophageal reflux (GER) in infants is most commonly thought of as repeated excessive vomiting and failure to thrive, with most infants responding favorably to medical therapy. However, GER may also manifest exclusively with a variety of respiratory symptoms that, if not detected and treated early, may lead to life-threatening complications. During the period of 1987 to 1992, 39 neonates and infants underwent Nissen fundoplication for the treatment of respiratory symptoms attributed to GER. Symptoms included apnea and bradycardia (64%), pneumonia (31%), cyanosis (28%), cough (18%), and stridor (15%). Most patients were ascribed at least one incorrect diagnosis to explain respiratory symptoms. These include apnea of prematurity (38%), bronchopulmonary dysplasia (31%), asthma (8%), and subglottic stenosis (8%). All patients underwent a variety of investigations and medical treatments without noticeable clinical improvement. These included bronchoscopy, esophagoscopy, and polysomnograms. Treatment such as antibiotics, theophylline, bronchodilators, steroids, and oxygen were directed at presumed primary respiratory disease. On the other hand, H2 blockers, metoclopramide, positioning, and thickened feeds were prescribed to treat GER without objective evidence of disease. Ultimately, GER was demonstrated by upper gastrointestinal series in 64%, pH probe in 61%, and both studies in 38%. All patients underwent Nissen fundoplication after failed attempts at medical therapy. A total of 95% of patients had resolution or substantial improvement of respiratory symptoms postoperatively. Preoperative hospitalization averaged 37.0 days, and postoperative stay averaged only 14.2 days. We present a series of patients with GER, all of whom presented with respiratory symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic and ventilatory effects of abdominal CO2 insufflation at various pressures in the young swine

Laparoscopic procedures requiring abdominal CO2 insufflation are applied with increasing frequency to the pediatric age group. Whereas the physiological effects accompanying insufflation have been studied in laboratory and clinical adult subjects, little is known of these effects in the juvenile subject. Young swine (weight, 10 to 12 kg, approximate age, 6 weeks) were subjected to abdominal CO2 insufflation at 10 and 15-mm Hg insufflation pressures (IP) to evaluate potential metabolic and hemodynamic effects. After intubation, minute ventilation was adjusted to obtain a baseline PCO2 between 38 and 42 mm Hg, and was kept constant during the subsequent study period. Four subjects underwent a total of eight trials, with insufflation periods of 1 hour each. Serial measurements of peak ventilatory pressure, tidal volume, end tidal CO2, arterial pH, PCO2, PO2, right atrial (RA), and inferior vena caval (IVC) pressure were obtained. Mean pH decreased from 7.45 +/- 0.03 to 7.22 +/- 0.03 at 10 mm Hg IP, and from 7.44 +/- 0.01 to 7.19 +/- 0.03 at 15 mm Hg IP. Mean PCO2 increased from 39.9 +/- 0.4 to 70.0 +/- 1.0 mm Hg at 10 mm Hg IP, and from 39.9 +/- 0.5 to 76.8 +/- 1.6 mm Hg at 15 mm Hg IP. PO2 decreased by approximately 37% at both IPs. End-tidal CO2 increased by 53% at 10 mm Hg IP, and by 68% at 15 mm Hg IP. Right atrial pressure did not increase significantly, and IVC pressure increased in proportion to the IP. Abdominal CO2 insufflation in this model produced marked acidemia, hypercapnia, decreased oxygenation, and increased exhaled CO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Thoracic epidural bupivacaine plus sufentanil: high concentration/low volume versus low concentration/high volume

BACKGROUND AND OBJECTIVES

To compare the postoperative analgesic and side effects of a continuous epidural infusion of bupivacaine with sufentanil: high concentration/low volume versus low concentration/high volume.

METHODS

In a prospective study, 30 patients scheduled for thoracic surgery had a thoracic epidural catheter inserted. Postoperative analgesia was provided by a continuous epidural infusion for 3 days. The patients were randomly divided into two groups: the low volume (LV) group (1.5 to 2 mL per hour of a combination of bupivacaine 0.5% with sufentanil 4 micrograms.mL-1) and the high volume (HV) group (6 to 8 mL per hour of a combination of bupivacaine 0.125% with sufentanil 1 microgram.mL-1).

RESULTS

The visual analogue scales were not different at rest or with exercise on days 1, 2, or 3. Supplemental analgesia by epidural catheter was necessary in half the patients in both groups. In two patients in the HV group and five patients in the LV group, a PaCO2 greater than mm Hg (7 kPa) was observed the first postoperative hour. Only on day 1 was the mean PaCO2 significantly increased in both groups (5.9 mm Hg [0.7] kPa in the LV group, and 6.0 mm Hg [0.4] kPa in the HV group) compared to the mean preoperative PaCO2 (5.1 mm Hg [0.5] kPa and 4.7 mm Hg [0.6] kPa). Between the groups there was no significant difference in PaCO2 at any time.

CONCLUSIONS

With the thoracic epidural administration of bupivacaine and sufentanil for postoperative analgesia, the total dose is more important than the concentration or the volume of the solution.