Influence of carbon dioxide pneumoperitoneum on the growth hormone-insulin-like growth factor I axis in mid- and late-pregnancy rats.

AIM: We investigated the influence of carbon dioxide (CO2) pneumoperitoneum on the growth hormone(GH)-insulin-like growth factor I (IGF-I) axis in mid- and late-pregnancy Sprague-Dawley rats. METHODS: A total of 48 mid-pregnancy rats were randomly assigned to one of three groups: anesthesia only (control group); 1-h CO2 pneumoperitoneum; or 2-h CO2 pneumoperitoneum. Blood samples were collected immediately after the procedure or in late pregnancy. Maternal concentration of serum GH and IGF-I was measured on enzyme-linked immunosorbent assay and compared between different groups. RESULTS: Under the same CO2 pneumoperitoneum pressure, serum GH and IGF-I concentration in the 2-h pneumoperitoneum group were significantly lower than those of the 1-h pneumoperitoneum group or the control group in both mid- and late pregnancy (P < 0.05), but there was no significant difference between the 1-h pneumoperitoneum group and the control group (P > 0.05). Serum GH and IGF-I concentrations were positively correlated in pregnant rats (R(2) = 0.3434, P < 0.05). CONCLUSIONS: Under the same CO2 pneumoperitoneum pressure, exposure duration was correlated with effect on maternal GH-IGF-I axis in mid- and late-pregnancy rats. Two h of exposure inhibited the GH-IGF-I axis in both mid- and late pregnancy, and therefore may restrict development of the placenta and fetus.

High-dose remifentanil suppresses stress response associated with pneumoperitoneum during laparoscopic colectomy.

PURPOSE: Although laparoscopic surgery is minimally invasive, it produces stress responses to an extent similar to that of conventional laparotomy. Both epidural anesthesia and remifentanil intravenously (i.v.), combined with general anesthesia, provide stable hemodynamics during laparoscopic surgery. However, it has not been elucidated whether epidural anesthesia and remifentanil are associated with suppression of autonomic and neuroendocrine stress responses. This study aimed to clarify whether thoracic epidural anesthesia (TEA) or remifentanil suppresses stress responses during laparoscopic surgery. METHODS: We assigned 60 patients undergoing laparoscopic colectomy to three groups anesthetized with 40 % oxygen-air-sevoflurane plus either TEA (TEA group), continuous infusion of remifentanil 0.25 µg/kg/min [low-dose (LD) group], or 1.0 µg/kg/min [high-dose (HD) group] (n = 20 each group). Plasma concentrations of adrenocorticotropic hormone (ACTH), cortisol, antidiuretic hormone (ADH), and catecholamines were measured immediately before anesthesia induction, and 30 and 90 min after the start of pneumoperitoneum. RESULTS: All groups showed no significant changes in hemodynamics during the course of anesthesia. Compared with TEA, both high-dose and low-dose remifentanil significantly suppressed increases in ACTH, ADH, and cortisol during pneumoperitoneum. Plasma adrenaline showed no significant changes during pneumoperitoneum in any group. Compared with TEA, low-dose remifentanil produced significantly higher plasma concentrations of noradrenaline and dopamine during pneumoperitoneum. CONCLUSION: Notwithstanding similar hemodynamic responses in all groups, only high-dose remifentanil suppressed both sympathetic responses and the hypothalamus-pituitary-adrenal axis. This result indicates that of these three anesthesia regimens, high-dose remifentanil seems most suited for laparoscopic surgery.

Inclusion of a nitric oxide congener in the insufflation gas repletes S-nitrosohemoglobin and stabilizes physiologic status during prolonged carbon dioxide pneumoperitoneum.

A method to maintain organ blood flow during laparoscopic surgery has not been developed. Here we determined if ethyl nitrite, an S-nitrosylating agent that would maintain nitric oxide bioactivity (the major regulator of tissue perfusion), might be an effective intervention to preserve physiologic status during prolonged pneumoperitoneum. The study was conducted on appropriately anesthetized adult swine; the period of pneumoperitoneum was 240 minutes. Cohorts consisted of an anesthesia control group and groups insufflated with CO2 alone or CO2 containing fixed amounts of ethyl nitrite (1-300 ppm). Insufflation with CO2 alone produced declines in splanchnic organ blood flows and it reduced circulating levels of S-nitrosohemoglobin (i.e., nitric oxide bioactivity); these reductions were obviated by ethyl nitrite. In a specific example, preservation of kidney blood flow with ethyl nitrite kept serum creatinine and blood urea nitrogen concentrations constant whereas in the CO2 alone group both increased as kidney blood flow declined. The data indicate ethyl nitrite can effectively attenuate insufflation-induced decreases in organ blood flow and nitric oxide bioactivity leading to reductions in markers of acute tissue injury. This simple intervention provides a method for controlling a major source of laparoscopic-related morbidity and mortality: tissue ischemia and altered postoperative organ function.

Efeitos do pneumoperitônio com ar e CO2 na gasometria de suínos / Effects of CO2 and air pneumoperitoneum on blood gas changes in pigs

OBJETIVO: O pneumoperitônio produz várias alterações na fisiologia humana. Algumas destas alterações, como hipercapnia e acidose, dependem ou säo agravadas com o uso de CO2, tendo maior repercussäo em pacientes com problema cardio-respiratório. A necessidade de uma melhor alternativa para insuflaçäo da cavidade; a observaçäo de que as cirurgias abertas, assim como as laparoscópicas com suspensäo mecânica, säo realizadas na presença de Ar ambiente; e a escassez de trabalhos testando o Ar em substituiçäo ao CO2 para insuflaçäo da cavidade, foram motivos para a realizaçäo deste trabalho. MÉTODOS: Vinte (0) suínos anestesiados foram submetidos a pneumoperitônio com 1 hora de duraçäo. Os animais foram distribuídos em 4 grupos de 5 animais: Grupo A1 - Pneumoperitônio de Ar a 10 mmHg; Grupo A - Pneumoperitônio de Ar a 16 mmHg; Grupo B1 - Pneumoperitônio de CO2 a 10 mmHg; Grupo B - Pneumoperitônio de CO2 a 16 mmHg. O pneumoperitônio foi realizado pela técnica aberta com trocater de Hasson. Através de um cateter venoso central colhe-se amostra de sangue para exame de gasometria em 3 momentos. RESULTADOS: A análise da gasometria venosa näo revelou alterações significativas entre os grupos em relaçäo a PaO2 e a saturaçäo do O2. Nos Grupos A1, A e B1 näo foram observadas alterações no equilíbrio ácido-básico. No Grupo B após uma hora de pneumoperitônio houve nítida tendência a hipercapnia e acidose. CONCLUSÄO: O ar, com a técnica aberta de pneumoperitônio foi uma opçäo segura para insuflaçäo de cavidade em procedimentos laparoscópicos diagnósticos de suínos

Vasopressin antagonist improves renal function in a rat model of pneumoperitoneum.

Pneumoperitoneum (PP) is associated with oliguria and increased plasma arginine vasopressin (AVP) levels. This study investigated the role of AVP in the pathogenesis of oliguria due to PP. Anesthetized and ventilated rats (n = 12) were subjected for 1 h to carbon dioxide PP with an intra-abdominal pressure of 8 mmHg or, as control, at 0 mmHg, before the determination of plasma AVP level. Another group of rats (n = 48) subjected to PP or control conditions was pretreated with the AVP V2 receptor antagonist, OPC-31260 (5 mg/kg), or vehicle, and their renal parameters were measured. Glomerular filtration rate (GFR) was determined by inulin clearance in an additional group of rats (n = 12) subjected to PP with or without pretreatment with OPC-31260. Rats subjected to PP had higher plasma AVP levels than did controls (17.3 +/- 8.1 pg/ml vs 1.5 +/- 0. 6 pg/ml, P < 0.05). In rats pretreated with vehicle, PP decreased urine output, excretion of water, and urea nitrogen, leading to reduced serum osmolality and serum sodium levels as well as elevated blood urea nitrogen levels. OPC-31260 pretreatment improved urine output, excretion of water, and urea nitrogen, thereby preventing changes in serum osmolality, serum sodium levels, and blood urea nitrogen levels. OPC-31260 pretreatment did not affect GFR. Results suggest that plasma AVP contributes to the oliguria due to PP. OPC-31260 may be useful in treating the water retention associated with PP.