Respiratory mechanics during laparoscopic cholecystectomy: the effects of the abdominal wall lift

The abdominal wall lift (AWL) has been proposed for laparoscopic cholecystectomy to reduce hemodynamic effects caused by carbon dioxide (CO2) and high intraabdominal pressures (IAP). Data concerning effects of AWL on respiratory mechanics are scant. We therefore used a noninvasive method to evaluate whether the AWL could offset these effects. The PETCO2, airflow, and airway pressure were continuously measured in nine patients undergoing laparoscopic cholecystectomy using an AWL with minimal CO2 insufflation. We used a least-squares method to calculate maximal airway pressure (Pmax), elastance (Ers), and resistances (Rrs) of the respiratory system. After CO2 insufflation, the initiation of AWL resulted in a significantly decreased IAP (from 13 to 6 mm Hg; P < 0.001) and Rrs (from 20.6 to 17.8 cm H2O.L(-1).s(-1); P = 0.029), whereas Ers was partly modified (34.0 to 33.3 cm H2O/L; not significantly different). With AWL, we hypothesized that the diaphragm remained flat and stiff, outweighing the beneficial effect of the decrease of IAP on Ers. PETCO2 significantly increased after AWL and at the end of the procedure. We conclude that AWL partly reverses the impairment of the respiratory mechanics induced by CO2 insufflation during laparoscopic surgery. IMPLICATIONS: The abdominal wall lift (AWL), acting on the abdominal chest wall, had some benefits during laparoscopic surgery by limiting CO2 peritoneal insufflation and several side effects, such as hemodynamics. We examined the consequences of this technique on respiratory mechanics in nine patients undergoing laparoscopic cholecystectomy. Our findings suggest that the AWL decreases intraabdominal pressure and respiratory resistances without a significant effect on respiratory elastance.     

Sputum and serum pharmacokinetics of loracarbef (LY163892) in patients with chronic bronchial sepsis

BACKGROUND: Carbon dioxide absorption into the blood during laparoscopic surgery using intraperitoneal carbon dioxide insufflation may lead to respiratory acidosis, increased ventilation requirements, and possible serious cardiovascular compromise. The relationship between increased carbon dioxide excretion (VCO2) and intraperitoneal carbon dioxide insufflation pressure has not been well defined. METHODS: In 12 anesthesized pigs instrumented for laparoscopic surgery, intraperitoneal carbon dioxide (n = 6) or helium (n = 6) insufflation pressure was increased in steps, and VCO2 (metabolic cart), dead space, and hemodynamics were measured during constant minute ventilation. RESULTS: VCO2 increases rapidly as intraperitoneal insufflation pressure increases from 0 to 10 mmHg; but from 10 to 25 mmHg, VCO2 does not increase much further. PaCO2 increases continuously as intraperitoneal insufflation pressure increases from 0 to 25 mmHg. Hemodynamic parameters remained stable. CONCLUSIONS: By considering Fick's law of diffusion, the initial increase in VCO2 is likely accounted for by increasing peritoneal surface area exposed during insufflation. The continued increase in PaCO2 without a corresponding increase in VCO2 is accounted for by increasing respiratory dead space.     

Orthotopic neobladder in management of tubercular thimble bladders: initial experience and long-term results

We describe a technique for endobronchial surgery with the neodynium:yttium-aluminum-garnet laser, in which an insufflation catheter with side holes placed into the contralateral mainstem bronchus is used for high-frequency positive pressure ventilation. Thirty-five patients (45 procedures) were treated during general anesthesia using a rigid bronchoscope in combination with a fiberoptic bronchoscope. Perioperatively, oxygen saturation (SaO2), mean arterial pressure, and heart rate were recorded. SaO2 during the recovery period was comparable to that during the intraoperative period but was significantly (P < 0.05) higher than that before the induction of anesthesia. There was a considerable (> or = 5%) increase in SaO2 at the end of the treatment in six patients, which indicates that the recanalization of the treated airway was successful. Our data support the assumption that, during endobronchial resection, selective ventilation of the nonaffected lung was adequate; in addition, subcarinal placement of the insufflation catheter with side holes was advantageous. We conclude that this technique contributes to the prevention of lung complications during endobronchial laser surgery. Implications: We describe a technique in which an insufflation catheter with side holes placed into the contralateral mainstem bronchus largely prevented inhalation of laser smoke and aspiration of blood and debris.     

Use of a laparoscopic insufflation port for ileal conduit endoscopy

We present an effective and simple technique for performing endoscopy of an ileal conduit. With a laparoscopic insufflation port in the stoma, a flexible cystoscope or ureteroscope can be inserted. The one-way valve of the port prevents leakage of irrigation fluid and allows the conduit to distend for optimal visualization. This technique is particularly useful when access to the upper urinary tracts is needed.     

The use of high-frequency jet ventilation for ventilatory support in an extreme case]

We report the case of a 27-year old man given a left lateral thoracotomy for emergency repair of the aortic isthmus, which had partially ruptured as a consequence of chest trauma. The patient also suffered serious trauma to the right lung, such that selective ventilation of that lung had to be applied with the left lung collapsed to allow the surgeon access to the descending aorta. Rapid decrease in SpO2 occurred, with excessively high airway pressures, requiring reinstatement of conventional ventilation of both lungs and interruption of surgery. Conventional ventilation was then replaced by high frequency jet ventilation to both lungs. That technique, combined with intermittent inflation of the left lung (inclined), provided sufficient oxygen as well as a wide and sufficiently immobile surgical field.     

Capnothorax: implications for the anaesthetist

Ten patients underwent a laparoscopic surgical technique for thoracic and cervical dissection of the oesophagus during oesophagogastrectomy. Thoracotomy was avoided with potential benefits to the patient. To facilitate surgical access the right lung was collapsed using a double-lumen bronchial tube and carbon dioxide was insufflated into the right pleural cavity to compress the lung. Changes in haemodynamic and respiratory variables occurred. In the majority of the patients airway pressure and end-tidal CO2 increased, despite alterations in ventilation. In five patients systolic blood pressure decreased suddenly by between 15 and 35 mmHg, and in four patients SpO2 decreased to 91% or less, despite an FIO2 of 1.0. If carbon dioxide was insufflated too fast, or the lung failed to deflate adequately, the clinical picture was that of a tension pneumothorax. One patient developed surgical emphysema and a contralateral pneumothorax. Postoperatively two patients had recurrent laryngeal nerve damage. Suggestions are made to minimise the changes in haemodynamic and respiratory variables during carbon dioxide insufflation into the thorax.     

Influence of age on cardiac pump function during laparoscopic cholecystectomy--measurements by ear densitography

Using ear densitography, consisting of photoelectric plethysomography and Holter electrocardiography, we measured systolic time intervals (STI) in 21 patients, ASA class 1 and 2, undergoing laparoscopic cholecystectomy using CO2 insufflation under general anesthesia (neuroleptanesthesia with isoflurane in air, FIO2 0.5). The patients were divided into two groups: Y-group (10 patients under 59 years of age) and O-group (11 patients over 60 years of age). We investigated the influence of age on cardiac pump function during pneumoperitoneum non-invasively. Y-group showed improvement of cardiac pump function (reduction of PEP/LVET) from 30 minutes after the beginning of insufflation and quick recovery of cardiac function immediately after deflation. O-group showed a tendency of increasing PaCO2 and arterial diastolic pressure, and delayed recovery of cardiac function (elongation of PEP at 60 minutes, and increase of PEP/LVET at 60 and 90 minutes, respectively, after insufflation). Hypertension and tachycardia were apparent immediately after pneumoperitoneum in the O-group. We conclude that special care and monitoring are mandatory for the aged patients with impaired cardiac or respiratory function during laparoscopic surgery.     

Cyclic hypoxic pulmonary vasoconstriction induced by concomitant carbon dioxide changes

We examined the stability of acute lobar hypoxic pulmonary vasoconstriction. In 12 mongrel dogs the left lower lobe (LLL) was selectively ventilated with a constant minute molume with nitrogen and the electromagnetically measured fraction of the cardiac output perfusing the LLL and the LLL end-tidal CO2 concentration were observed for 1 h. We found that both the fraction of the cardiac output perfusing the LLL and the LLL end-tidal CO2 concentration initially decreased during LLL hypoxia and then oxcillated in a progressively damped fashion. When LLL end-tidal CO2 was kept constant by CO2 infusion during LLL hypoxia or when LLL hypoxia was induced by LLL atelectasis, no oscillations were observed. We conclude that if minute ventilation of a hypoxic area of lung is kept constant, then decreased regional blood flow decreases regional alveolar PCO2. As a consequence of these two opposing influences, blood flow to an acutely hypoxic area will be oscillatory.     

Effects of peritoneal insufflation on hepatic and renal blood flow

The effects of peritoneal insufflation with carbon dioxide on hepatic and renal blood flow have not been reported hitherto. We evaluated these effects in a porcine model of abdominal laparoscopic surgery. Seven anesthetized pigs underwent peritoneal insufflation in a step-wise manner to create intraabdominal pressures of 6, 12, 18 and 24 mmHg, and changes in the arterial and venous pressure, arterial blood gases, and hepatic and renal blood flow were monitored. Both the hepatic and renal blood flow decreased as the intraabdominal pressure increased. Therefore, in order to carry out laparoscopic abdominal surgery safely in patients with hepatic or renal impairment, low intraabdominal pressures or noninsufflating techniques are recommended.     

The laryngeal mask airway and positive-pressure ventilation

BACKGROUND: The utility of the laryngeal mask airway during positive-pressure ventilation has yet to be determined. Our study was designed to assess whether significant leaks occurred with positive-pressure ventilation and if leaks were associated with gastroesophageal insufflation. METHODS: Forty-eight patients undergoing elective surgery were studied. After induction of anesthesia and paralysis, controlled ventilation was used with four different peak pressure settings in each patient (15, 20, 25, and 30 cmH2O). The order of ventilator pressure settings was assigned from a randomized block schedule. Data collected included inspiratory and expiratory volumes, qualitative assessments of gastroesophageal insufflation, and leak at the neck. After data collection during laryngeal mask use, the anesthesiologist intubated the trachea and measurements were repeated for tracheal tube ventilation. Leak was calculated by subtracting the expiratory from the inspiratory volume and expressed as a fraction of the inspiratory volume. RESULTS: Ventilation with the laryngeal mask airway was adequate at all ventilation pressures and comparable with tracheal tube ventilation. Leak fraction (mean +/- SD) at 15, 20, 25, and 30 cmH2O for laryngeal mask ventilation were 0.13 +/- 0.15, 0.21 +/- 0.18, 0.25 +/- 0.16 and 0.27 +/- 0.17, respectively, and 0.03 +/- 0.03, 0.05 +/- 0.03, 0.05 +/- 0.03 and 0.04 +/- 0.03, respectively, for tracheal tube ventilation. Leak fractions for ventilation with the laryngeal mask were consistently greater than those measured for tracheal tube ventilation at similar ventilation pressures. Leak fraction with laryngeal mask ventilation increased with increasing airway pressures, whereas leak with tracheal tube ventilation remained unchanged. The frequency of gastroesophageal insufflation ranged from 2.1% at a ventilation pressure of 15 cmH2O to 35.4% at 30 cmH2O. CONCLUSIONS: Ventilation using the laryngeal mask appears to be adequate if airway resistance and pulmonary compliance are normal. Gastroesophageal insufflation of air will become a problem in the presence increased ventilation pressure.     

The effects of space flight on the production of monorden by Humicola fuscoatra WC5157 in solid-state fermentation

BACKGROUND: There is growing evidence that laparoscopy for malignancy is associated with an increased incidence of metastasis to port sites. This study investigated the effect of different insufflation gases on port-site metastasis after laparoscopy in an established animal model. METHODS: Forty-eight Dark Agouti rats with an established adenocarcinoma in the left flank underwent laparoscopic intraperitoneal tumor laceration. The gas used for insufflation was one of the following (12 rats in each group): (1) CO2, (2) N2O, (3) helium, or (4) air. Rats were killed 7 days after the procedure, and the port sites were examined for the presence of tumor metastasis. RESULTS: Tumor involvement of port sites was significantly less likely after helium insufflation than in the other groups (p < 0.0001). There was no significant difference between the air, CO2, and N2O groups. CONCLUSIONS: This study suggests that the development of metastases in port sites after laparoscopy may be influenced in part by the choice of insufflation gas used to create the pneumoperitoneum. In particular, helium was associated with a reduced rate of metastases.     

Effects of carbon dioxide pneumoperitoneum, air pneumoperitoneum, and gasless laparoscopy on body weight and tumor growth

BACKGROUND: The oncologic consequences of intraperitoneal carbon dioxide (CO2) insufflation during the laparoscopic resection of cancer are under debate. The effect of other insufflating gases or gasless laparoscopy on cancer requires study. OBJECTIVE: To study body weight and tumor growth in rats after CO2 pneumoperitoneum, air pneumoperitoneum, and gasless laparoscopy. METHODS: On day 1, an 8-mg bolus of ROS-1 tumor was placed under the renal capsule of both kidneys in rats. In experiment A, rats had either CO2 insufflation (n=10) or a gasless laparoscopic bowel resection (n=10) on day 3 and were humanely killed after 7 days. In experiment B, rats had either a laparoscopic bowel resection with CO2 insufflation (n=11) or insufflation with air (n=11) on day 3 and were killed after 7 days. In both experiments, postoperative weight loss and tumor growth were measured, and the differences were tested with an analysis of covariance. RESULTS: Renal subcapsular tumor growth in the group having gasless laparoscopy was less than that in the group having CO2 pneumoperitoneum (P=.04). Postoperative weight loss in these groups showed no differences (P=.55). No differences in tumor growth or weight loss were found between rats having insufflation with CO2 and those having insufflation with air (P=.61 and P=.68, respectively). CONCLUSIONS: The restoration of body weight after a laparoscopic surgical procedure was similar with CO2, air, or gasless laparoscopy. Gasless laparoscopy was associated with less renal subcapsular tumor growth than was insufflation with CO2. Therefore, the application of gasless techniques in laparoscopic oncologic surgical treatment demands further study.     

Hemodynamic changes during laparoscopic cholecystectomy

Hemodynamics during laparoscopic cholecystectomy under general anesthesia (isoflurane in N2O/O2 (50%)) were investigated in 15 nonobese ASA Class I patients by using invasive hemodynamic monitoring including a flow-directed pulmonary artery catheter. During surgery, intraabdominal pressure was maintained automatically at 14 mm Hg by a CO2 insufflator, and minute ventilation was controlled and adjusted to avoid hypercapnia. Hemodynamics were measured before anesthesia, after the induction of anesthesia, after tilting into 10 degrees head-up position, 5 min, 15 min, and 30 min after peritoneal insufflation, and 30 min after exsufflation. Induction of anesthesia decreased significantly mean arterial pressure and cardiac index (CI). Tilting the patient to the head-up position reduced cardiac preload and caused further reduction of CI. Peritoneal insufflation resulted in a significant increase (+/- 35%) of mean arterial pressure, a significant reduction (+/- 20%) of CI, and a significant increase of systemic (+/- 65%) and pulmonary (+/- 90%) vascular resistances. The combined effect of anesthesia, head-up tilt, and peritoneal insufflation produced a 50% decrease in CI. Administration of increasing concentrations of isoflurane, via its vasodilatory activity, may have partially blunted these hemodynamic changes. These results demonstrate that laparoscopy for cholecystectomy in head-up position results in significant hemodynamic changes in healthy patients, particularly at the induction of pneumoperitoneum.     

Transoesophageal echocardiographic assessment of haemodynamic function during laparoscopic cholecystectomy

We have measured cardiovascular changes associated with insufflation of carbon dioxide and the reverse Trendelenburg position during laparoscopic cholecystectomy, using transoesophageal echocardiography in 13 healthy patients. End-tidal carbon dioxide values increased after insufflation of carbon dioxide, with values significantly (P < 0.05) increased after lateral tilt positioning. Creation of a pneumoperitoneum was associated with increases (P < 0.05) in left ventricular end-systolic wall stress, concomitant with increases (P < 0.01) in peak airway pressure and systemic arterial pressure. In addition, left ventricular end-diastolic area decreased (P < 0.05) after reverse Trendelenburg positioning. Left ventricular ejection fraction was maintained throughout the study.     

Clinical evaluation of single-tooth restorations supported by osseointegrated implants: a retrospective study

Unilateral whole lung lavage (UWLL) was performed four times in a patient with pulmonary alveolar proteinosis. PaO2 was 94 Torr even under ventilation with 100% O2. Because of the difficulty in providing adequate arterial oxygenation, extracorporeal membrane oxygenation (ECMO) was indispensable in accomplishing the first right UWLL. During the second left UWLL, the left lung was ventilated with nitrogen (N2) and an attempt was made to predict the lowest PaO2 occurring during lavage in order to establish criteria for the use of ECMO during UWLL. When both lungs were ventilated with 100%. O2, PaO2 rose to 150 Torr. PaO2 fell to 65 Torr after ventilation of the left lung with N2 while the right lung was ventilated with 100% O2 for 7 minutes. The N2 was replaced with 100% O2 and ventilation was continued for another 10 minutes to wash the N2 out of the left lung. When the tracheal tube in the left lung was clamped for 7 minutes for degassing, PaO2 fell to 59 Torr. Subsequently 1,200 ml of physiological saline was injected into the left lung, and PaO2 rose to 155 Torr. A 6 Torr difference was found between the value of PaO2 under ventilation with N2 and that of degassing, but this difference was not statistically significant. The lowest PaO2 occurring during UWLL was considered to be predictable if the unilateral lung was ventilated with N2.     

Blood gas changes during laparoscopic cholecystectomy--comparative study of N2O pneumoperitoneum and CO2 pneumoperitoneum

During laparoscopic cholecystectomy by alternative insufflation of nitrous oxide and carbon dioxide, the changes of blood gas tensions were measured and analyzed in 12 patients. During N2O insufflation, PaO2 decreased by about 25 mmHg and PaCO2 was unaltered compared with the values before pneumoperitoneum. While during CO2 insufflation, PaO2 decreased by about 13 mmHg and PaCO2 increased by about 6 mmHg. We considered that decrease in PaO2 during N2O insufflation was associated with not only uneven ventilation/blood flow ratios but also with the reduction in the alveolar O2 tension caused by the diffusion of N2O absorbed from the peritoneum. PaCO2 increases during CO2 insufflation because CO2 is absorbed from the peritoneum, and is not excreted entirely through the lungs.     

Effect of propranolol and nifedipine on maximal electroshock-induced seizures in mice: individually and in combination

To clarify the influence of the head-up position on cerebral oxygen metabolism during laparoscopy with CO2 insufflation in 12 patients who underwent laparoscopic cholecystectomy, changes in the concentrations of cerebral oxyhemoglobin (HbO2), deoxyhemoglobin (Hb), total hemoglobin (total Hb) and oxidized cytochrome aa3 (Cyt aa3) were measured by use of near-infrared laser spectroscopy. Anesthesia was maintained with nitrous oxide (66%), oxygen, and sevoflurane. Pneumoperitoneum was maintained at an intraabdominal pressure of 10-12 mm Hg by use of CO2. Minute ventilation was adjusted to maintain end-tidal CO2 tension (P(ET)CO2) between 35 and 40 mm Hg during the procedure. Patients were moved from supine to the head-up (20 degree) position before intraabdominal manipulation. The concentration of HbO2 decreased significantly when patients were moved to the head-up position and 30 min thereafter. It remained significantly low after they were returned to the supine position and at the end of surgery. The concentration of Hb was unchanged during the study. Therefore, the concentration of total Hb decreased significantly when patients were moved to the head-up position, as well as 30 min thereafter. It remained significantly low after they were returned to the supine position and at the end of surgery. The concentration of Cyt aa3, however, did not change significantly during the study. These results suggest that the head-up position during laparoscopic cholecystectomy decreases cerebral HbO2 and total Hb.     

Late post-partum hemorrhage after cesarean section due to rupture of a false aneurysm of the uterine pedicle

We report a 14 year-old girl with a huge adenomatous goiter in the left lobe in the thyroid gland reaching the aortic arch with elevated thyroglobulin. The tumor grew rapidly for two years since the initial diagnosis as an euthyroid hemilateral goiter. Ultrasonography revealed multinodular tumors and magnetic resonance imaging made clear the lower expanding site of the tumor. We recommend careful follow up of hemilateral diffuse goiters by ultrasonography for earlier detection of nodular changes as seen in our case.     

The power of suggestion: another examination of misattribution and insomnia

Impairment of mucous transport is considered significant to the postoperative development of atelectasis, but the association has never beed demonstrated in humans. Tantalum powder, which adheres to airway mucus, can be used to study mucociliary transport. The postoperative clearance of insufflated tantalum powder (mean diameter, 2.5 mum) was investigated in 25 patients. Eighteen patients underwent intra-abdominal vascular surgery and 7 undersent lower-extremity orthopedic procedures. At the completion of surgery, tantalum was insufflated into both lungs of each patient to outline a representative sample of airways from the trachea to the small bronchi. Tantalum clearance was evaluated from serial radiographs obtained immediately after insufflation, at approximately 6, 18, 26, and 48 hours later, and thereafter whenever appropriate. In the 7 orthopedic patients, clearance of tantalum was progressive and usually complete within 48 hours. Atelectasis did not occur in this group. In 14 of the 18 patients who had abdominal surgery, mucociliary clearance was markedly abnormal in that tantalum was retained for up to 6 days. Pooling of tantalum-labeled mucus occurred in dependent bronchi in 16 of these 18 patients. Pooling preceded and always accompanied radiographically visible atelectasis. Lobar atelectasis occurred in 6 patients and segmental atelectasis in 8. Tantalum-labeled mucus moved peripherally in atelectatic lobes or segments and was retained in these bronchi until re-expansion took place. Thus, impaired ciliary function and mucous transport are associated with and implicated in postoperative pulmonary atelectasis.     

New acetylene based histamine H3 receptor antagonists derived from the marine natural product verongamine

BACKGROUND: Respiratory failure secondary to cardiopulmonary bypass (CPB) remains a major complication after cardiac surgery. We tested the hypothesis that post-CPB lung function impairment can be prevented by continuous positive airway pressure (CPAP) applied during the CPB. METHODS: In 6 pigs, CPAP with 5 cmH2O pressure was applied during CPB. Six other pigs served as control, i.e. the lungs were open to the atmosphere during CPB. After median sternotomy, the right atrial appendage as well as the ascending aorta were cannulated. The total CPB duration was 90 min with 45 min cardioplegic arrest. Ventilation-perfusion distribution was measured with the multiple inert gas elimination technique and atelectasis by CT-scanning. RESULTS: Large atelectasis appeared after CPB, corresponding to 14.5% +/- 5.5 (percent of the total lung area) in the CPAP group and 18.7% +/- 5.2 in the controls (P = 0.20). Intrapulmonary shunt increased and PaO2 decreased after the CPB in both groups. CONCLUSIONS: We conclude that in this pig model post-CPB atelectasis is not effectively prevented by CPAP applied during CPB.