Laparoscopic colon surgery: unreliability of end-tidal CO2 monitoring.

BACKGROUND: The relatively good haemodynamic and respiratory tolerance to abdominal CO(2) insufflation has mostly been observed in healthy patients during short-lasting laparoscopic procedures. End-tidal CO(2) pressure (PetCO(2)) has been shown to be a reliable method to assess arterial CO(2) (PaCO(2)) in the absence of cardio-respiratory disease in this setting. However, no study has investigated whether PetCO(2) is accurately related to PaCO(2) during laparoscopic colon surgery. Indeed, these procedures last longer, prolonging the pneumoperitoneum and requiring a Trendelenburg position. The aim of the present study was to measure the PaCO(2)-PetCO(2) difference over time in patients undergoing laparoscopic colon surgery and to determine whether PaCO(2) is reliably assessed by PetCO(2). METHODS: Forty consecutive patients (ASA I and II) scheduled for laparoscopic colon surgery were anaesthetized and ventilated to obtain a PetCO(2) between 4.0 and 5.5 kPa. After initiation of CO(2) insufflation, PaCO(2) and PetCO(2) were recorded every 30 min during surgery. RESULTS: No complication was observed during anaesthesia. The mean arterial pressure increased significantly after CO(2) insufflation and remained steady up to the end of pneumoperitoneum. The heart rate remained stable over time. The relation between PaCO(2) and PetCO(2) was not constant among patients and increased over time within the same patients. The R(2) values fluctuated and did not show a constant correlation between PaCO(2) and PetCO(2). CONCLUSION: The correlation between PaCO(2) and PetCO(2) during laparoscopic colon surgery is inconsistent mainly due to inter- and intra-individual variability.

Hepatopulmonary syndrome increases the postoperative mortality rate following liver transplantation: a prospective study in 90 patients.

Hepatopulmonary syndrome (HPS) is a frequent pulmonary complication of patients with end-stage liver diseases. HPS is diagnosed by hypoxemia and pulmonary vascular dilatation and is an independent risk factor of mortality. Orthotopic liver transplantation (OLT) is the only factor that modifies the natural course of HPS. Once patients with HPS have been transplanted, their long-term survival rate is similar to transplanted patients without HPS. Consequently, HPS is an indication of OLT whatever the severity of hypoxemia. However, besides the favorable long-term survival of HPS patients with OLT, a high postoperative mortality (mostly within 6 months) has been suggested. The aim of our study was to analyze the incidence of HPS and postoperative outcome after OLT in 90 consecutive patients. All patients were prospectively included and had blood gas analysis to detect HPS. Patients with hypoxemia had contrast echocardiography to confirm HPS. Nine patients had HPS with a 50 50 mmHg in all HPS patients transplanted.

The quantitative distinction between train-of-four "counts of 2" and posttetanic "counts of 2" evidenced by a stable paralysis/stable infusion rate method in anesthetized patients receiving mivacurium.

In this study we quantitatively evaluated, by a stable paralysis/stable infusion rate method, the difference between two standardized paralysis levels--train-of-four (TOF) count of 2 responses and posttetanic count (PTC) of 2. Ten ASA physical status I-II consenting adult patients scheduled for elective surgery were anesthetized (sufentanil/propofol), tracheally intubated, mechanically normoventilated with a fixed O(2)/air mixture, and normothermic; oropharynx and thenar temperatures were maintained above 36 degrees and 32.5 degrees C, respectively. After partial recovery from 200 microg/kg mivacurium (MIV), stable tactile TOF and PTC counts of 2 paralysis levels were induced on the adductor pollicis muscle by manual adjustments of an infusion pump containing MIV. The paralysis levels and the infusion rates were considered as stable once they remained constant at 4 consecutive time points separated by 5 min each. Infusion rates observed were: TOF count 2-6 (2-11) and PTC 2-17 (3-18) microg . kg(-1) . min(-1) (P < 0.001; Wilcoxon's paired comparison test). Under the present conditions, obtaining and maintaining a PTC of 2 requires MIV infusion rates far in excess of the "standard" recommendations mentioned in the literature for MIV infusion management.

Are there reliable predictors of postoperative pain?

BACKGROUND: The purpose of this study was to identify the preoperative determinants of severe postoperative pain. METHODS: Potential predictors were assessed using a questionnaire submitted on the day before surgery. Pain at rest, and pain during coughing/mobilization, were measured using visual analog scales on the day of surgery and on the following 2 days. The type of postoperative pain management was not standardized and was prescribed by the anesthesiologist in charge. Multivariate logistic regression models explaining postoperative pain were developed in Group I, comprising 304 consecutive patients undergoing orthopedic or intraperitoneal surgery, and validated in Group II, comprising 145 independent patients. RESULTS: Of the 62 variables examined by univariate analysis, only five were found to increase the risk of severe postoperative pain in Group I at rest and six factors during cough/mobilization. In the multivariate model for pain at rest, general anesthesia, expectation of postoperative pain, and chronic sleeping difficulties increased the risk of severe postoperative pain. In Group II, only chronic sleeping difficulties remained (OR: 3.97, 95% Cl: 1.69-9.29). In the multivariate model during cough/mobilization, intraperitoneal surgery, fear of postoperative pain, and having a relative with a history of pain increased the risk of severe postoperative pain in Group I. Intraperitoneal surgery OR 2.45 (95% Cl = 1.01-4.50) and having a relative with a history of pain OR 2.06 (95% Cl = 1.005-4.50) remained in Group II. CONCLUSION: Of the many factors that may influence postoperative pain, chronic sleeping difficulties emerge in this population of patients as the strongest determinant of pain at rest. Intraperitoneal surgery and having a relative with a history of pain are the strongest determinants of pain during cough/mobilization. These findings make physiological sense and deserve more attention by anesthesiologists.

[Start of an adult living donor liver transplantation program in Switzerland]. / Début d'un programme adulte de donneurs vivants de foie en Suisse.

The shortage of cadaver organs has prompted transplant centres to seek new sources of grafts. While living-donor left lobe transplantation (segments II and III) is an established procedure for children, living donor right liver transplantation (segments V, VI, VII, VIII), which can provide adequate liver mass for an average-sized adult patient, is technically more demanding and potentially associated with higher risks for the donor. In view of the permanent shortage of organs in Switzerland, we started an adult living donor liver transplantation programme in 1999 with the approval of the Clinical Ethics Committee of Geneva University Hospitals. Donor evaluation was performed only after the recipient had been officially registered for transplantation in the national waiting list. Preoperative evaluation consisted of a preliminary information phase with blood tests and Doppler ultrasonography, a second phase with radiological non invasive investigations (CT scan with volume measurements, magnetic resonance cholangiography) and a third phase including liver biopsy and angiography. A formal psychiatric evaluation was performed in all cases and detailed consent was required. Eight potential donors were investigated, 5 were not retained because of too small right liver or steatosis, and 3 were accepted (wife, son, sister). Living-donor hepatectomy was performed without interrupting the vascular blood flow. The liver graft was perfused ex-situ with University of Wisconsin solution. The grafts were anastomosed to the preserved vena cava of the recipient and the portal and arterial anastomoses were performed without interposition grafts, with short cold ischaemic times in the 3 cases. The graft-to-recipient weight ratio ranged from 1.04 to 1.12%. The grafts worked immediately; the post-operative course in the 3 recipients was unremarkable and no rejection episode occurred. Significant complications were observed in one donor (percutaneously drained bilioma and spontaneously resolved popliteal sensory palsy). Living-donor right liver transplantation is a potentially valuable solution to the increasing shortage of donor organs. The procedure can be performed safely provided stringent criteria for donor selection, for donor-recipient coupling (> 1% graft to body weight ratio) and for centre selection (experience in liver surgery, reduced and split liver transplantation) are applied.

Anesthetic assessment in an outpatient consultation clinic reduces preoperative anxiety.

PURPOSE: Preoperative anxiety in relation to anesthesia remains for many patients a major subject of concern. The aim of the present study was to compare the level of preoperative anxiety in patients assessed in an outpatient consultation clinic with the anxiety level of those having been assessed by the anesthesiologist after entering the hospital. METHOD: We studied two groups of 20 patients who underwent elective transurethral prostate or bladder resection: group A having the anesthetic assessment between one-two weeks before hospitalisation, group B having this assessment the evening before surgery, after entering the hospital. Two different methods to assess anxiety were used: the Multiple-Affect-Adjective-Check-List (MAACL) and the visual analogue scale of anxiety (VAS). RESULTS: Both anxiety provided scores, assessed by two different methods, were lower in group A, than in group B(P<0.01). CONCLUSION: The results of this study confirm that an anesthetic assessment in an outpatient consultation clinic reduces preoperative anxiety, when compared with an assessment on the evening before surgery.

Pain intensity and pain relief after surgery. A comparison between patients' reported assessments and nurses' and physicians' observations.

BACKGROUND: Postoperative pain remains a problem for many patients. One of the reasons could lie in the insufficient evaluation of pain and analgesia. This study was designed to obtain more insight in the performance of nurses and physicians in evaluating patients' postoperative pain and pain relief. METHODS: Forty patients hospitalised in one surgical unit and the 8 nurses and the 2 surgical residents in charge of this unit were investigated. Patients were asked to assess on a visual analogue scale the intensity of their pain and their pain relief at rest, on coughing and globally since the operation, on the first and second postoperative days and the day before hospital discharge. Separately, the nurses and the physicians were asked to evaluate the pain intensity and the pain relief for each patient involved. A MANOVA and a multiple comparisons test with Bonferroni adjustment were used. RESULTS: At rest, only nurses underestimated pain intensity on the day before hospital discharge. On coughing, physicians underestimated pain intensity in all 3 assessments, whereas nurses only in the 3rd assessment (on the day before hospital discharge). Globally, physicians underestimated pain intensity in all 3 assessments, nurses in the 2nd and the 3rd assessment. Only physicians overestimated pain relief on coughing on the day before hospital discharge and globally in all 3 assessments. Surprisingly, the pain scores rated by the patients before hospital discharge were high. CONCLUSION: The results of this survey suggest that assessment of pain and pain relief is inadequately done by both physicians and nurses. This emphasises the importance of a better training, and a systematic assessment of pain intensity and pain relief.

Treatment efficacy is not an index of pain intensity.

PURPOSE: To determine if the efficacy of pain treatment assessed by the patient is a valid indicator to evaluate pain management. METHODS: Three hundred and ninety one adult patients were investigated on the day of surgery and on the two following days after intraperitoneal or orthopedic surgery. Pain scores and efficacy of pain treatment were evaluated using ungraduated visual analog scales (VAS). According to the evolution of pain between two consecutive days, patients were classified as having "worse pain", "same pain" or "lower pain". RESULTS: During the first time interval, pain treatment was considered effective by 42% of patients with worse pain, compared with 55% with less pain (OR= 1.9, 95% CI=1.1-3.7) and to 58% of patients with the same pain (OR =2.0, 95%CI=1.2-3.0). During the second time interval, these proportions were: 46% (worse pain), 63% (lower pain vs worse: OR= 1.8, 95%CI= 1.0-3.2) and 66% (same pain vs worse: OR=2.1, 95%CI=1.1-4.1). Using pain evolution as a"gold standard", patient assessment of pain treatment efficacy had sensitivity of 0.55 and specificity 0.5 during the first time interval, and of 0.63 and 0.43 during the second time interval. CONCLUSION: Patient evaluation of the efficacy of pain treatment can mislead the clinician about the severity of pain. Patients tend to be satisfied with pain treatment, even when pain is not relieved. The relation of intensity of pain to patient perception of treatment efficacy is weak.

[Halogenated anesthetic vaporizers: importance of maintenance regulations]. / Evaporateurs d'anesthésiques halogénés: importance des prescriptions d'entretien.

We report a serious dysfunction of 19 halothane vaporisers Vapor 19.3 (Dräger) which delivered a much higher concentration of agent than indicated on the dial. This inaccuracy was linked to a major corrosion of the inner layers of the vaporiser, with a deposit of zinc bromide and chloride in the bypass channel. The main cause for this dysfunction was the absence of an adequate maintenance of the vaporisers since their purchase 3 years before.

Effects of abdominal CO2 insufflation and changes of position on hepatic blood flow in anesthetized pigs.

During surgical laparoscopy, total hepatic blood flow (THBF) may be modified by CO2 insufflation, changes of tilt, ventilation with high tidal volume, hypercapnia, and anesthesia, but little information is available on the THBF during the procedure. To investigate the changes of hepatic blood flow following the combination of abdominal CO2 insufflation and changes of tilt, we measured mean arterial pressure (MAP), cardiac output, portal vein blood flow (PVBF), and hepatic artery blood flow (HABF) in anesthetized and ventilated pigs. CO2 was insufflated in the abdomen [intra-abdominal pressure (IAP) approximately 15 mmHg], and the hepatic blood flow was measured in various positions (horizontal, 10 degrees and 20 degrees head down, and 10 degrees and 20 degrees head up) before and during CO2 insufflation. CO2 insufflation in the horizontal position did not modify MAP, cardiac output, or PVBF but increased HABF. The head-up tilt decreased MAP, cardiac output, and both hepatic flows in the absence of pneumoperitoneum, but in the presence of abdominal CO2 only cardiac output and PVBF were decreased. The head-down tilt increased MAP and THBF in the absence of pneumoperitoneum, whereas no change was observed in the presence of abdominal CO2. The combination of CO2 insufflation and changes of tilt was not deleterious to hepatic perfusion. These results suggest that hepatic blood flow may be preserved during surgical laparoscopy if the tilt does not exceed 20 degrees and if IAP after CO2 insufflation remains <15 mmHg.

Checking the anaesthetic machine: self-reported assessment in a university hospital.

Checking the anaesthetic machine before its daily use is essential. The aim of our study was to evaluate, through the use of an anonymous questionnaire, how the anaesthetists of our institution (physicians and nurses) report their daily checking. Sixty-three questions were used to ask the participants how frequently they checked the main components of the anaesthetic machine; the answers were evaluated with a score (0-3). The overall response rate was 78%, nurses; rate being lower than physicians' rate. Nurses obtained a higher global score, which raises the question of different adherence to guidelines by nurses and physicians. Moreover, questions in relation to gas supply were badly scored by all participants, which should alert us to reinforce theoretical and practical training in these items. Finally, although the methodology used in this survey could raise the question of the best way to evaluate the actual checkout procedure, self-reported assessment remains an alternative to more complex and expensive methods, such as an observer or a video evaluation.

The influence of an aging surgical population on the anesthesia workload: a ten-year survey.

UNLABELLED: To assess the evolution of the anesthetic workload related to elderly population (> or = 65 yr) at the University Hospital of Geneva, the total number of anesthesia cases, high-risk patients, and emergency procedures, as well as the total duration of anesthesia and incidence of perianesthetic complications, were retrospectively analyzed over 10 yr. The squared correlation coefficient was used to assess the proportion of variance explained by the linear regression of the absolute and the relative number of events over time. More than 165,000 anesthesia procedures were analyzed, and the data were separated into two groups: the younger population (<65 yr) and the elderly population (> or = 65 yr). From 1985 to 1994, the elderly surgical population grew significantly faster (P < 0.001) than the elderly resident population (from 20.3% to 25.1% versus from 12.5% to 13.6%). Half of the increased number of anesthesia cases during this period were administered to elderly patients. The number of high-risk elderly patients increased by 48.3% (P < 0.0001). The number of emergency procedures in elderly patients increased only until 1991, and a significant decrease in the incidence of perianesthetic complications was observed. Because the mean duration of each procedure remained constant, the increased anesthetic workload in our institution was mainly due to increased geriatric surgical activity. IMPLICATIONS: During a study period of 10 yr, the increased anesthetic workload (defined as the number of anesthesia cases, high-risk patients, emergency procedures, and complication rate) at the University Hospital of Geneva was mainly due to the increased geriatric (patients > or = 65 yr) surgical activity, not to the aging of the resident population.

Preoperative clinical assessment of hemostatic function in patients scheduled for a cardiac operation.

BACKGROUND: Bleeding during and after cardiac operations is usually attributed to inadequate surgical hemostasis or cardiopulmonary bypass-induced disorders of hemostasis. Patient-related factors often are neglected. METHODS: Articles published between 1976 and 1996 on the preoperative assessment of surgical patients were reviewed to determine the clinical elements most likely to predict increased perioperative blood requirements. RESULTS: Preoperative assessment is based on a carefully conducted interview (history of bruising, petechiae, recent or excessive bleeding after operation, chronic drug therapy) and physical examination. A standardized questionnaire to enhance the reliability of the assessment is presented. Thus, patients at high risk of being transfused can be identified early on and may be enrolled in various programs designed to decrease bleeding and the need for allogeneic blood transfusions. CONCLUSIONS: Clinical assessment of hemostatic function before cardiac operations is both effective and efficient. It obviates the need for routine laboratory testing and favors the introduction of blood conservation strategies early on during the process of care.

Hemodynamic effects of intermittent pneumatic compression of the lower limbs during laparoscopic cholecystectomy.

BACKGROUND: The effects of surgical pneumoperitoneum on lower-limb venous hemodynamics have already been studied; however, the effects of intermittent compression boots are not known in such venous-stasis conditions. METHODS: In 12 volunteers and 12 patients, the venous hemodynamic effects of intermittent leg compression were studied under external abdominal pressure or during laparoscopic cholecystectomy, respectively. Femoral venous diameter and velocity were measured. Venous pressure was monitored during the surgical procedures. RESULTS: External abdominal pressure of 50 mm Hg and pneumoperitoneum were found to increase the diameter (17% in the volunteers and 14% in the patients) and decrease peak velocity (49% and 32%, respectively) in the femoral vein. Femoral pressure was increased (106%) during pneumoperitoneum. In both venous-stasis circumstances, intermittent compression of the legs restored venous flow velocity, but had no effect on vessel diameter and pressure. CONCLUSIONS: The lower-limb venous hemodynamic changes were similar during external abdominal pressure or pneumoperitoneum, and the flow velocity decrease was intermittently reversed by pneumatic compression boots.

Cardiovascular reflexes during anesthesia induction and tracheal intubation in elderly patients: the influence of thoracic epidural anesthesia.

STUDY OBJECTIVES: To determine whether thoracic epidural anesthesia performed prior to general anesthesia provides hemodynamic protection from the stress of laryngoscopy and tracheal intubation; to access the autonomic reflex response to epidural anesthesia, general anesthesia, and airway stimulation. DESIGN: Randomized unblind, controlled study. PATIENTS AND SETTING: 20 elderly (over 60) patients scheduled for colonic or gastric surgery at a university medical center. INTERVENTIONS: All patients (n = 10, in each group) underwent a standardized anesthesia induction sequence that included fentanyl 2 micrograms/kg, thiopental sodium 3 to 5 mg/kg (up to loss of eyelid reflex), and vecuronium 0.1 mg/kg followed by laryngoscopy and tracheal intubation. Before general anesthesia, thoracic epidural anesthesia was performed with plain 1% lidocaine in the epidural group. Preoperatively, baroreflex function was assessed by the Valsalva maneuver and the cough test. Spectral analysis of heart rate (HR) variability was performed before as well as during anesthesia. MEASUREMENTS AND MAIN RESULTS: There were no differences between the two groups in basal hemodynamics autonomic reflex status. Thoracic epidural anesthesia (median upper level at T2, median lower level at L2) was associated with stable hemodynamics, preservation of baroreflex sensitivity, and increased ratio of low to high frequency (LF/HF) components of HR variability, suggesting withdrawal of vagal activity. In both groups, general anesthesia induction was associated with decreased total HR variability and tracheal intubation was followed by increased LF/HF ratio, reflecting cardiac sympathetic activation. Patients with thoracic epidural anesthesia presented significant attenuation of the maximal rise in mean arterial pressure, and the increase in HR tended to be lower although not significantly. CONCLUSIONS: Thoracic epidural blockade combined with general anesthesia was associated with preserved baroreflex function, and it afforded hemodynamic protection during laryngoscopy and tracheal intubation.

Laparoscopic extraperitoneal inguinal hernia repair complicated by subcutaneous emphysema.

The case of a healthy 59-yr-old man who underwent elective laparoscopic extraperitoneal inguinal hernia repair and general anaesthesia is presented. After one hour of surgery, a sudden increase in the FETCO2 from 5.0% to 9.4% in relation to a massive subcutaneous emphysema, but without any haemodynamic instability, was noticed. The acute rise of FETCO2 was the first sign of an abnormal event. Nevertheless, subcutaneous emphysema was diagnosed with chest wall examination and palpation. Subcutaneous emphysema and hypercarbia are potential complications of laparoscopic surgery, but are more likely to occur in extraperitoneal surgery, since insufflated CO2 can diffuse easily into the surrounding tissues. High insufflation pressures will increase chances of this occurring and was the most likely cause of this complication. This case encouraged us to make recommendations for the management of laparoscopic extraperitoneal surgery which included: monitoring of CO2 insufflation pressure, routine examination and palpation of chest wall, use of N2O with caution, adjusting ventilation to physiological FETCO2 and excluding other causes of subcutaneous emphysema and hypercarbia.

Effect of dynamic exercise on left atrial function in conscious dogs.

1. Dynamic changes in left atrial (LA) function during treadmill exercise were studied in ten conscious dogs instrumented to measure left ventricular (LV) pressure and diameter, LA pressure and diameter, and pulmonary venous blood flow (PVF, transit time flowmeter). 2. Systolic PVF volume (reservoir volume; a measure of LA reservoir function) increased from 38 +/- 4% of total PVF volume at baseline to 52 +/- 8% of total PVF volume during exercise, and diastolic PVF volume (conduit volume; a measure of LA conduit function) decreased from 62 +/- 5% at baseline to 48 +/- 8% during exercise (P < 0.005). 3. The increases in reservoir volume and the decrease in conduit volume were due not only to a greater decrease in diastolic interval than systolic interval but were also caused by a significantly greater increase (P < 0.05) in the mean systolic filling rate (93%) than in the mean diastolic filling rate (51%). 4. During exercise the pattern of LV filling derived from changes in LV diameter showed that a greater percentage of LV filling occurred during the second half of diastole at the time of atrial contraction (P < 0.05), suggesting that LA booster function was enhanced. 5. Changes in LA dimension revealed that during exercise more blood volume was reserved in the LA during systole and that this change was associated with an increase in the LA dimension at the beginning of LA contraction (r = 0.61, P < 0.05). 6. We conclude that LA reservoir and booster functions were augmented during exercise, whereas conduit function was not. Increased reservoir function may play an important role in accelerating LV filling by helping to maintain an enhanced atrioventricular pressure gradient during diastole and also by increasing LA booster function through an increase in LA preload.

Absence of agonist effects of high-dose flumazenil on ventilation and psychometric performance in human volunteers.

Flumazenil, a specific benzodiazepine antagonist, reverses sedative and respiratory depressant effects of benzodiazepines. We determined whether a large dose of flumazenil, injected alone, induces respiratory depression or alteration of psychomotor performance. After informed consent, eight healthy volunteers participated at three different sessions: 1) flumazenil (0.1 mg/kg) (a dose 7-15 times the clinically recommended dose) injected intravenously over a 5-min period, followed by placebo (NaCl 0.9%); 2) flumazenil at the same dose and injection rate as in Session 1, followed by midazolam (0.1 mg/kg) injected over 5 min; and 3) placebo followed by midazolam at the same dose as above and administered over 5 min. All drug combinations were administered in a randomized and double-blind manner. Tidal volume, respiratory frequency, minute ventilation, and mean inspiratory flow were continuously measured from 15 min before until 120 min after drug injection by noninvasive on-line data acquisition methods. Psychometric performance was evaluated 15 min before the first drug and 15 min after administration of the second drug. During the placebo-midazolam session, tidal volume (-40%), minute ventilation (-25%), and inspiratory flow (-25%) were significantly (P < 0.01) decreased compared both with baseline and with the other two sessions, and psychometric performance was significantly (P < 0.01) altered; in contrast, there was no significant change in any of the measured respiratory or psychometric variables during the flumazenil-placebo or flumazenil-midazolam sessions. We conclude that flumazenil, administered at about 10 times the clinically recommended dose, has no agonist effects on resting ventilation or psychomotor performance in normal subjects.