Maternal and neonatal outcome after cesarean section: the impact of anesthesia.

BACKGROUND: Among the anesthetic technologies used, regional anesthesia is becoming the most common in cesarean section (CS) deliveries. Aim. This retrospective survey examined the variables taken into account when selecting the anesthetic technique to be used, and how this choice affects the outcome for the mother and the newborn. METHODS: One thousand eight hundred and seventy elective and emergency CS were evaluated for anesthetic technique used, indications, and maternal and neonatal outcome. RESULTS: Of the 611 elective CS (32.6%), 206 (33.8%) were performed under general anesthesia and 405 (66.2%) under regional anesthesia. Of the 1259 emergency CS performed (67.4%), 525 (41.9%) were under general anesthesia and 734 (58.1%) under regional anesthesia. Conditions associated with a newborn 1-minute Apgar score of <7 were general anesthesia and multiple pregnancy (p<0.01); a 5-minute Apgar score of <7 was only associated with multiple pregnancy. The most important factor for very low Apgar scores was the presence of fetal malformations. Whatever the chosen technique, neither maternal deaths directly or indirectly due to the anesthesia nor major maternal and perinatal complications were found. CONCLUSIONS: This survey confirms the preference for regional anesthesia during elective cesarean sections and for general anesthesia in emergency situations. Moreover, newborn outcome was found not to be influenced either by the technique used or by the character of the procedure.

Comparison of clinical and pathological staging and long-term results of liver transplantation for hepatocellular carcinoma in a single transplant center.

Liver transplantation (OLT) is a treatment for hepatocellular carcinoma (HCC) superimposed on cirrhosis provided that the disease meets defined criteria. The aim of the study was to evaluate our experience with respect to clinical and pathological staging and long-term results. From 1996 to 2005, 50 patients underwent OLT for HCC including 43 men (86%) and seven women (14%) of median age 57 years (range 37 to 67). All patients fulfilled the Milan criteria. The HCC diagnosis was based on preoperative imaging and alpha-fetoprotein levels; no tumor biopsy was performed. Upon histological examination of the resected specimens, we discovered 6 (12%) incidentalomas and 8 (16%) cases of no HCC. Finally we had 42 "true" HCC. Twenty-six patients (52%) have been downstaged and 10 (20%) upstaged by preoperative imaging; 15% were pT1, 45% were pT2, 27% pT3, and 13% pT4a. Twenty-six percent of cases exceeded the Milan criteria. One patient (pT4a) with microvascular invasion died of pulmonary metastases at 14 months after transplantation. No HCC recurrences within the liver have been encountered at a median follow-up of 20 months (range 0 to 80 months). Overall the estimated 1-, 3-, and 5-year survival rates were 83%, 77%, and 72%, respectively. One-, 3-, and 5-year estimated survival rates were 87%, 75%, and 75% for pT1, and pT2, and 75%, 67%, and 67% for pT3 and pT4a, respectively (P = .99). Based on our experience OLT for HCC has long-term results comparable to those without HCC despite the presence of a significant number of cases exceeding the Milan criteria upon pathological staging.

Secondary migration of a central venous catheter. A case report.

A case of central venous catheter (CVC) secondary migration in a patient with Hodgkin's lymphoma is reported. The catheter was inserted in the right internal jugular vein with anterior approach. The correct position of the catheter tip in the superior vena cava was confirmed by X-ray. Secondary migration to the right subclavian vein, without displacement at the point of insertion, was reported 8 days later by a chest X-ray performed for worsening of the respiratory condition. CVC was removed and reinserted with the same procedure. The correct position of the catheter tip was confirmed by thoracic radiography till 10 days later. Epidemiological data present in the literature and secondary migration predisposing factors are reported.

A new method of preemptive analgesia in laparoscopic cholecystectomy.

BACKGROUND: Although laparoscopic cholecystectomy (LC) results in less pain then open cholecystectomy, it is not a pain-free procedure. The aim of this study was to test a new method of preemptive analgesia. METHODS: By simple randomization 60 patients were assigned to two groups (30 in each group). Group A, the placebo group, received 200 ml of 0.9% saline, and group B received 5 mg/kg of a local anesthetic solution (ropivacaine) in 200 ml of 0.9% saline. Local anesthetic or placebo solution were administer before creation of the pneumoperitoneum. RESULTS: Pain intensity, as rated by visual analog and verbal rating scales, and stress response data were significantly less in the group receiving ropivacaine than in the placebo group. No patients in treatment group received an additional dose of analgesic, whereas two patients in placebo group needed an additional analgesic. CONCLUSIONS: Our results support the clinical validity of preemptive analgesia, but the timing of intraperitoneal administration of local anesthetic is very important. Only application before creation of the pneumoperitoneum may preempt every neuronal central sensitization.

Application of a clinical score for the diagnosis of acute appendicitis in childhood: a retrospective analysis of 197 patients.

PURPOSE: The aim of this study was to validate a clinical scoring system for the diagnosis of acute appendicitis in childhood. METHODS: The authors retrospectively applied a clinical scoring system on 197 consecutive pediatric patients operated on for acute appendicitis. They therefore looked for a correlation between the management suggested by the scoring system and pathologic diagnosis on surgical specimens. RESULTS: Based on final pathologic specimen, surgery has been performed unnecessarily in 23% of cases. The proposed scoring system could have reduced unnecessary surgery to 2%. Only 8% of patients with acute appendicitis would have been discharged home. Sensitivity and specificity of the scoring system used in this study was 87% and 86%, respectively. CONCLUSION: The clinical scoring system proposed in this study could be of help in early clinical diagnosis of appendicitis to reduce the rate of unnecessary emergency surgery.

Prevention of post-herpetic neuralgia: acyclovir and prednisolone versus epidural local anesthetic and methylprednisolone.

BACKGROUND: Treatment of herpes zoster (HZ) includes the use of acyclovir with or without steroids. An alternative therapy is the epidural administration of local anesthetics with or without steroids. This trial compared the efficacy of these two treatment regimens in the prevention of post-herpetic neuralgia (PHN). METHODS: Six hundred adults over 55 years of age with a rash of less than 7 days duration, and severe pain due to HZ, were enrolled and randomized to receive either intravenous acyclovir (10 mg/kg three times daily) for 9 days+prednisolone (60 mg per day with progressive reduction) for 21 days, or 6-12 ml bupivacaine (0.25%) every 6-8 or 12 h+methylprednisolone 40 mg every 3-4 days by epidural catheter during a period ranging from 7 to 21 days. Efficacy was evaluated at 1, 3, 6 and 12 months. PHN was assessed as pain and/or allodynia, and "abnormal sensations" (hypoesthesia, burning, itching, etc.). Statistical analysis was performed based on the intent-to-treat population. RESULTS: In the 485 patients who completed the study, the incidence of pain after 1 year was 22.2% (51 patients of 230) after acyclovir+steroids, and 1.6% (4 patients of 255) after epidural analgesia+steroids. The incidence of abnormal sensations was 12.2% (28 patients) after acyclovir+steroids, and 4.3% (11 patients) in group B. CONCLUSIONS: Epidural administration of local anesthetic and methylprednisolone is significantly more effective in preventing PHN at 12 months compared to intravenous acyclovir and prednisolone.

The hemodynamic and metabolic effects of tourniquet application during knee surgery.

UNLABELLED: We evaluated the effects of tourniquet application on the cardiovascular system and metabolism in 10 young men undergoing knee surgery with general anesthesia. The duration of inflation was from 75 to 108 min. Heart rate, mean arterial pressure, cardiac index (CI) by pulse contour method, and systemic vascular resistance were measured before, during, and after tourniquet inflation. pH, PaO(2), PaCO(2), and lactate blood concentrations were also measured. VO(2) and VCO(2) were assessed every minute from tracheal intubation up to 15 min after tourniquet deflation and VO(2) in excess of the basal value over the 15 min after deflation (VO(2)exc) was calculated. Mean arterial pressure increased 26% (P: < 0.05) during inflation and returned to basal values after deflation. CI did not change immediately after inflation; although, thereafter, it increased 18% (P: < 0.05). Five minutes after deflation, CI further increased to a value 40% higher than the basal value. Therefore, systemic vascular resistance increased 20% suddenly after inflation (P: < 0.05) and decreased 18% after deflation (P: < 0.05). VO(2) and VCO(2) remained stable during inflation and increased (P: < 0.05) after deflation. VO(2)exc depended on duration of tourniquet inflation time (Tisch) (P: < 0.05). After deflation, PaCO(2) and lactate increased (P: < 0.05) while Tisch increased. We conclude that tourniquet application induces modifications of the cardiovascular system and metabolism, which depend on tourniquet phase and on Tisch. Whether these modifications could be relevant in patients with poor physical conditions is not known. IMPLICATIONS: The clinical effects of tourniquet application were evaluated in 10 young men undergoing knee surgery. Our data indicate that tourniquet application causes hemodynamic and metabolic changes which may become clinically relevant after a long period of tourniquet inflation, particularly in patients with concomitant cardiovascular diseases.

Haemodynamic effects of intravenous clonidine on propofol or thiopental induction.

The study evaluated the effects of premedication with intravenous clonidine on thiopental or propofol requirements for induction and haemodynamic changes associated with both induction and endotracheal intubation. Clonidine administered intravenously before induction of anaesthesia reduced propofol or thiopental requirements. The association of clonidine and propofol caused, after injection of the induction drug, a decrease in mean arterial pressure which was significantly greater than with thiopental. Moreover, a major haemodynamic stability was registered before and after laryngoscopy in the clonidine-thiopental group. These findings might contraindicate the clonidine-propofol combination in patients with cardiovascular disease.

Laparoscopic treatment of symptomatic lymphoceles after kidney transplantation.

BACKGROUND: The incidence of lymphocele after kidney transplantation ranges from 0.6% to 18%. This study examines the use of laparoscopic ultrasound for the location of lymphoceles during laparoscopic drainage. METHODS: Between July 1993 and October 1998, we performed 147 kidney transplants. A symptomatic lymphocele was observed in 19 patients (12.9%). All of these patients underwent peritoneal laparoscopic fenestration of the lymphocele. The graft, kidney hilum, ureter, iliac vessels, and lymphoceles were identified by laparoscopic ultrasound. RESULTS: All but one patient were discharged within 24 h. One recurrence (5.2%), which was successfully treated by laparoscopy, was observed at a mean follow-up of 15.5 months. We had one complication (5.2 %)-a left hydrocele that occurred 2 days after drainage of a lymphocele located in the left iliac fossa. CONCLUSIONS: Laparoscopic peritoneal drainage of posttransplant lymphoceles shares the well known advantages of laparoscopy. Furthermore, laparoscopic ultrasound is a useful tool that allows the recognition of anatomical structures and decreases the risk of iatrogenic lesions.

Laparoscopic vs open splenectomy in the management of hematologic diseases.

BACKGROUND: Laparoscopic splenectomy (LS) is becoming the gold standard in the treatment of several splenic diseases. Shorter postoperative stay and more rapid return to full activity are the primary advantages of LS. METHODS: Prospective data collection of 44 consecutive LS (group 1) and comparison with a historical control group of 56 consecutive open splenectomies (OS) (group 2) were performed for hematologic diseases. RESULTS: The LS patients started earlier on an oral diet (p < 0.0001) and left the hospital sooner (p < 0.0002) than OS patients. Less blood transfusion (p < 0.004) and pain medication (p < 0.0001) was required by LS patients. They also had fewer postoperative complications (p < 0.03). Compared by diagnosis, patients with laparoscopic idiopathic thrombocytopenic purpura or Hodgkin's disease started to eat earlier (p < 0.0001) and left the hospital sooner (p < 0.01). Multivariate analysis showed that time to oral diet and postoperative stay was related to operative technique and age. Morbidity and pain medications were related, respectively, to transfusion requirements and type of surgical approach. CONCLUSIONS: Used to manage hematologic diseases, LS is feasible, effective, and safe. It offers several advantages over the open approach. The type of surgical approach seems to be the crucial factor in determining the length of the postoperative course.

Laparoscopic splenectomy for haematological diseases: review of current concepts and opinions.

Laparoscopic splenectomy is now currently used by most surgeons in the treatment of many haematological diseases. The operative technique varies depending on the surgeon, but results are usually comparable among published series. We have reviewed 104 papers about laparoscopic splenectomy for haematological diseases and paid particular attention to surgical aspects and early postoperative results. We searched MEDLINE from January 1989 to April 1998, and of the 104 papers that we found 41 fulfilled our criteria of large series published in peer-reviewed journals that had been cited often. They usually compared laparoscopic and open splenectomy and focused on common problems (such as accessory spleens) and technical aspects (such as bleeding). Laparoscopic splenectomy is reported by most authors to be as safe and effective as open splenectomy for haematological diseases. It also has several advantages over the open approach, such as shorter and less complicated postoperative stay with better cosmetic results and more rapid return to full activities.

[Herpes Zoster and post-herpetic neuralgia: everything to revise?]. / Herpes Zoster e nevralgia post-herpetica: tutto da rivedere?

The treatment and prevention of the algic symptomatology of Post-Herpetic Neuralgia (PHN) are problems still to be solved. In our opinion the reason of this failure is to be found in an insufficient knowledge of the pathophysiological phenomena which cause the PHN. In fact, many fundamental aspects, such as its "temporal" and symptomatological definition and its pathogenesis are still unsolved. This revision tries to focus the problems and discrepancies hindering an improvement in PHN treatment and prevention. The literature reports three different symptomatological levels after herpes zoster acute phase: patients affected by pain and/or allodynia, patients with "abnormal sensations" (anesthesia, paresthesia, dysesthesia, prickling, itching, burning, etc.,) and patients in "complete recovery". Only two studies have analyzed the final incidence of these symptomatologies. Therefore, it is absolutely unclear whether the patients in "abnormal sensations", that is with a symptomatology which is definitely less weakening than pain, have to be considered in PHN (patients with pain) or in "complete recovery". On the contrary, from a clinical and physiopathological point of view this symptomatological difference may have a great importance: the symptomatological non-distinction could be the cause of the disagreement concerning PHN incidence data; this distinction could differentiate and compare in a reliable way the effects of the various therapies reported in the literature. The lack of a symptomatological classification does not facilitate a verification of the physiopathological hypothesis of PHN onset and maintenance. The differentiation among pain, "abnormal sensations" and "complete recovery" could correlate these three symptomatological conditions to the anatomopathological and viral data which according to literature characterize the evolution of Herpes Zoster acute phase in PHN. This would largely help to improve the therapeutic strategy.

Elective transumbilical compared with standard laparoscopic cholecystectomy.

OBJECTIVE: To compare the transumbilical technique of laparoscopic cholecystectomy with standard laparoscopic cholecystectomy. DESIGN: Randomised open study. SETTING: Teaching hospital, Italy. SUBJECTS: 90 patients who required elective cholecystectomy under general anaesthesia. INTERVENTIONS: Standard laparoscopic cholecystectomy through 4 ports or transumbilical cholecystectomy through 2 ports. MAIN OUTCOME MEASURES: Amount of pain and analgesia, cost, side effects, and cosmesis. RESULTS: 25 patients were excluded from analysis (8 in the standard group because relevant data were not recorded; and 17 in the transumbilical group in 4 of whom relevant data were not recorded, and 13 for technical reasons). 32 patients who had standard, and 25 who had transumbilical cholecystectomy had operative cholangiograms. There were no complications, no side effects, and no conversions to open cholecystectomy. Those who had transumbilical cholecystectomy had significantly lower pain scores (p<0.05) and required significantly less analgesia during the first 24 hours (p<0.05) than those who had standard laparoscopic cholecystectomy. CONCLUSION: Once the learning curve has been completed, transumbilical cholecystectomy is possible without some of difficulties associated with standard laparoscopic cholecystectomy.

Experimental and clinical studies about the preemptive analgesia with local anesthetics. Possible reasons of the failure.

Though we fully agree with the truthfulness of the physiopathological sequences proving the phenomena of the hyperalgesia onset and therefore a prolongation of the postoperative pain, we do not believe, as stated by some authors that the studies carried out up to now, both experimental and clinical, are sufficient, the first ones to confirm the preemptive analgesia, while the second ones to be defined as contrasting and totally inadequate to confirm the preemptive analgesia effect. The lack of positive clinical data is why some authors have suggested a "revision" and a "reduction" of the word preemptive analgesia. On the contrary, we believe that differences which seem to originate from the clinical works can also be found in the experimental ones if we examine them with the same methodological principle. In order to classify better such an important treatment like the preemptive analgesia, the aim of this note is to focus the attention on the experimental and clinical data. Our criterion to select the works has based on a backwards research taking into consideration the last reviews and studies about the preemptive analgesia. Since the results obtained with local anesthetics or with opioids seem to counterbalance each other, we have reexamined the experimental and clinical works limiting our attention to the local anesthetics. On a total of 19 assessments carried out in 16 experimental studies, only three of the eight ones comparing pre-vs post-administration prove a real preemptive analgesia effect of the local anesthetic (block of the first and second phase of hyperexcitability) whereas four of the eleven clinical studies examined seem to confirm the validity of the preemptive analgesia effect. These data show how the results of the experimental studies are equal to the results of the clinical ones. However, an important characteristic that seems to come out from these works is connected to two elements strictly linked each other: the intensity and the duration of the nociceptive impulse produced and the level and the type of the induced block. In our opinion, the failure of many of these works can be attributed to the inadequacy of the analgesic levels (intensity of the block) reached and maintained in the pre-and intraoperative period. Therefore we believe that before thinking of a "review" and "reduction" of the word preemptive analgesia is necessary to take a step backward and to face again the methodological problems of the preemptive analgesia.

Laparoscopic versus open splenectomy in the management of splenomegaly: our preliminary experience.

BACKGROUND: Laparoscopic splenectomy for normal-sized spleens has several advantages compared with laparotomy. Only a few cases of splenomegaly done by laparoscopy are reported in the literature. The purpose of this study is to show that laparoscopy for splenomegaly is feasible and has several advantages over the open operation. METHODS: We performed retrospective chart review of 8 cases of splenomegaly managed by laparoscopy (group 1), 15 cases of open splenomegaly (group 2), and 27 cases of laparoscopic splenectomy for normal-sized spleens (group 3). Comparison has been done between groups 1 and 2 and groups 1 and 3 in terms of operative time, intraoperative estimated blood loss, need for blood transfusion, postoperative ileus, postoperative stay, and mortality and morbidity rates. RESULTS: Patients in group 1 required longer operative time and significantly less intraoperative blood transfusion compared with group 2. The postoperative course was less complicated and shorter in group 1 than in group 2. Operative time was longer in group 1 compared with group 3. No significant differences in terms of postoperative course have been found between groups 1 and 3. CONCLUSIONS: Laparoscopy for splenomegaly is a feasible, effective, and safe technique for experienced laparoscopic surgeons. This approach seems to have several advantages over the open operation. Prospective, randomized trials would be required for a proper quantitative evaluation.

Preemptive analgesia: intraperitoneal local anesthetic in laparoscopic cholecystectomy. A randomized, double-blind, placebo-controlled study.

BACKGROUND: A controversy exists over the effectiveness and clinical value of preemptive analgesia. Additional studies are needed to define the optimum intensity, duration, and timing of analgesia relative to incision and surgery. METHODS: One hundred twenty patients undergoing laparoscopic cholecystectomy under general anesthesia plus topical peritoneal local anesthetic or saline were studied. Local anesthetic (0.5% bupivacaine with epinephrine) or placebo solutions were given as follows: immediately after the creation of a pneumoperitoneum (blocking before surgery), and at the end of the operation (blocking after surgery). Patients were randomly assigned to one of four groups of 30 patients each. Group A (placebo) received 20 ml 0.9% saline both before and after surgery, group B received 20 ml 0.9% saline before surgery and 20 ml local anesthetic after surgery, group C received 20 ml local anesthetic both before and after surgery, group P received 20 ml local anesthetic before and 20 ml 0.9% saline after surgery. Pain was assessed using a visual analog scale and a verbal rating scale at 0, 4, 8, 12, and 24 h after surgery. Metabolic endocrine responses (blood glucose and cortisol concentrations) and analgesic requirements also were investigated. RESULTS: Pain intensity (visual analog and verbal rating scales) and analgesic requirements were significantly less in the group receiving bupivacaine after surgery compared to placebo. However, in the groups receiving bupivacaine before surgery, both pain intensity and analgesic consumption were less than in the group receiving bupivacaine only after surgery. Blood glucose and cortisol concentrations 3 h after surgery were significantly less in groups receiving bupivacaine before surgery. CONCLUSIONS: The results indicate that intraperitoneal local anesthetic blockade administered before or after surgery preempts postoperative pain relative to an untreated placebo-control condition. However, the timing of administration is also important in that postoperative pain intensity and analgesic consumption are both lower among patients treated with local anesthetic before versus after surgery.

[Trans-umbilical cholecystectomy: a new laparoscopic cholecystectomy technique. Description of the technique and preliminary results]. / Colecistectomia trans-ombelicale: nuova tecnica di videolaparo-colecistectomia. Illustrazione della tecnica e risultati preliminari.

The aim of videolaparo-cholecystectomy is to achieve a good results with minimal surgical trauma. Recently there has been an evolution of this technique toward the progressive reduction of trauma with an improvement of the results, also from the aesthetical point of view. In this article we describe our new videolaparo-cholecystectomy technique. Trans-umbilical videolaparo-cholecystectomy represents a variant of the traditional technique. This new method allows the operation to perform with only two trocars positioned in the peritoneum cavity through only one umbilical incision. The technical innovation of this method consists of the substitution of the others trocars, utilized in the traditional technique, with an equal number of trans-parietal suspension wires. Up to now, we have given 95 patients this kind of operation being successful in 67% of the cases. We think that this new technique, requiring as it does only standard laparoscopic instruments, is in accordance with the philosophy of mini-invasive surgery. The suspension wires are responsible for minimal bile spreading which is not an important complication if the surgeon performs an accurate and through cleaning of the abdominal cavity at the end of the surgical procedure. The patient better accepts this technique because of its better aesthetical results. In spite of this there should be more evaluable data about trans-umbilical videolaparo-cholecystectomy especially about the incidence of post-operatory complications.

The effects of intraperitoneal local anesthetic on analgesic requirements and endocrine response after laparoscopic cholecystectomy: a randomized double-blind controlled study.

This randomized double-blind placebo-controlled study was designed to evaluate the effects on postoperative pain of the local anesthetic, 0.5% bupivacaine with epinephrine, sprayed hepatodiaphragmatically under the surgeon's direct view during laparoscopic cholecystectomy. Metabolic endocrine responses to surgery (glucose and cortisol) and nonsteroidal anti-inflammatory drug requirements were investigated, as well as the presence of nausea, vomiting, and sweating. Local anesthetics or placebo solutions were given as follows. Immediately following the creation of a pneumoperitoneum, surgeons sprayed the first 20 mL of solution (S1), and an additional 20 mL of solution (S2) was sprayed at the end of the operation. Patients were classified into three groups (14 patients per group). Group A received 20 mL of saline during both S1 and S2, group B received 20 mL of saline during S1 and 20 mL of bupivacaine during S2, and group C received 20 mL of bupivacaine during both S1 and S2. The degree of postoperative pain was assessed using the visual analogue scale (VAS) and the verbal rating scale (VRS) on arrival in the recovery room and subsequently at time intervals of 4 h, 8 h, 12 h, and 24 h. The results of this study indicate a significant decrease of postoperative pain in patients treated with local anesthetic. VAS and VRS pain scores, as well as respiratory rate and analgesic requirements, were significantly lower in group C. The postoperative plasma cortisol level in group C was significantly lower than in groups A and B.

[Effects of age, body weight, and ventilatory pattern on the difference between arterial and end-tidal PCO2]. / Effetti di età, peso corporeo e pattern ventilatorio sulla differenza tra PCO2 arteriosa e fine espirazione.

OBJECTIVE: To evaluate the effects of physiological ventilatory patterns on P(a-ET)CO2 gradient and on the alveolar dead space production during controlled mechanical ventilation. DESIGN: Prospective and experimental comparison among three different ventilatory settings in three different groups of subjects. SETTING: General surgery's operating-theatre in university hospital. PATIENTS: Twenty-eight patients subdivided randomly in 3 groups differing for ventilatory setting. I group: constant tidal volume (VC = 8 ml.kg-1) and 3 different respiratory frequencies (f = 10, 12 and 14 breaths.min-1); II group: constant ventilation (112 ml.kg-1) but VC and f modified in three different ways; III group: inspiratory volume was set to give an end-tidal PCO2 (PETCO2) of about 35 mmHg. The cases were subdivided, on the basis of P(a-ET)CO2 distribution, in three groups: group with values larger than mean plus 1 standard deviation, group with values between +/- 1 standard deviation and group with values lower than mean minus 1 standard deviation. Moreover in two homogeneous groups for age. INTERVENTIONS: General surgery but not important because measures were performed before surgical manoeuvres. MEASUREMENTS AND MAIN RESULTS: Anthropometrical data (age and body weight), PaCO2, PETCO2, heart rate, invasive arterial pressure, ventilatory parameters and airway pressure were collected for every subject and ventilatory setting; arterial to end-tidal difference P(a-ET)CO2 and P(a-ET)CO2.PaCO2(-1) were calculated during data analysis. The P(a-ETFCO2 and P(a-ET)CO2.PaCO2(-1) values were not significantly different among the three different ventilatory patterns both in the first and in the second group. P(a-ET)CO2 values were significantly correlated with age, body weight and airway pressure. These parameters were correlated significantly also with P(a-ET)CO2.PaCO2(-1) values. CONCLUSIONS: Ventilatory setting, used in a normal physiological range, don't affect P(a-ET)CO2 difference during mechanical ventilation. Age, body weight and airway pressure of the patient must be considered to obtain a correct value of PaCO2 by the measure of PETCO2.