Pulmonary function following laparoscopic or conventional colorectal resection: a randomized controlled evaluation

BACKGROUND: Laparotomy causes a significant reduction of pulmonary function, and atelectasis and pneumonia occur after elective conventional colorectal resections. OBJECTIVE: To evaluate the hypothesis that pulmonary function is less restricted after laparoscopic than after conventional colorectal resection. DESIGN: A randomized clinical trial. SETTING: The surgical department of an academic medical center. PATIENTS: Sixty patients underwent laparoscopic (n = 30) or conventional (n = 30) resection of colorectal tumors. The 2 groups did not differ significantly in age, sex, localization or stage of tumor, or preoperative pulmonary function. MAIN OUTCOME MEASURES: Forced vital capacity, forced expiratory volume in 1 second, peak expiratory flow, mid-expiratory phase of forced expiratory flow, and oxygen saturation of arterial blood. RESULTS: The forced vital capacity (mean +/- SD values: conventional resection group, 1.73+/-0.60 L; laparoscopic surgery group, 2.59+/-1.11 L; P<.01) and the forced expiratory volume in 1 second (conventional resection group, 1.19+/-0.51 L/s; laparoscopic surgery group, 1.80+/-0.80 L/s; P<.01) were more profoundly suppressed in the patients having conventional resection than in those having laparoscopic surgery. Similar results were found for the peak expiratory flow (conventional resection group, 2.51+/-1.37 L/s; laparoscopic resection group, 3.60+/-2.22 L/s; P<.05) and the midexpiratory phase of forced expiratory flow (conventional resection group, 1.87+/-1.12 L/s; laparoscopic surgery group, 2.67+/-1.76 L/s; P<.05). The oxygen saturation of arterial blood, measured while the patients were breathing room air, was lower after conventional than after laparoscopic resections (P<.01). The recovery of the forced vital capacity and forced expiratory volume in 1 second to 80% of the preoperative value took longer in patients having conventional resection than in those having laparoscopic resection (P<.01). Pneumonia developed in 2 patients having conventional resection, but no pulmonary infection occurred in the laparoscopic resection group (P>.05). CONCLUSIONS: Pulmonary function is better preserved after laparoscopic than after conventional colorectal resection. Pulmonary complications may be reduced after laparoscopic resections because of the better postoperative pulmonary function.     

Effect of bcr-abl oligodeoxynucleotides on the clonogenic growth of chronic myelogenous leukaemia cells

Two-dimensional echocardiographic (2-D) planimetry and the Doppler pressure half-time (PHT) method have been used to estimate mitral valve area (MVA) in patients with mitral stenosis (MS). Recently, the proximal isovelocity surface area (PISA) method has been shown to be accurate for calculating MVA. The purpose of this study was to compare the PISA method with previous methods. Thirty patients with MS were studied; 17 had pure MS, 4 combined mild MR, 6 combined mild AR, and 3 combined MR and AR. Color Doppler flow mapping was performed at an aliasing (blue-red interface) velocity of 14 cm/sec using the zero-baseline shift. MVA was calculated as 2 x 3.14 x R2 x 14 x (theta/180) / PFV, where R is the distance from aliasing to orifice, 14 is the aliasing velocity, theta is the internal angle of the mitral valve, and PFV is the peak flow velocity at the mitral orifice. MVA was also calculated using the 2-D and PHT methods, and compared with the PISA method. MVA calculated using the PISA method correlated well with the 2-D (r=0.90, p < 0.01, SEE = 0.18 cm2) and PHT methods (r=0.82, p < 0.01, SEE = 0.24 cm2). Compared with the 2-D method, the standard error of the estimate of the PISA method was - 0.14+/-0.18 cm2 and the percent error was -10.4+/-18.9%. Compared with the PHT method, the standard error of the estimate of the PISA method was + 0.01+/-0.24 cm2 and the percent error was +3.4+/-34.6%. MVA calculated using the PISA method correlated well with the 2-D and PHT methods in patients with pure MS or with MS combined mild regurgitation. The PISA method may be useful for calculating MVA as an alternative method.     

Properties of the catalytic center of a secretory 28kDa protein (1-cys peroxiredoxin) from rat olfactory epithelium

BACKGROUND: Percutaneous mitral valvuloplasty with the Inoue balloon is conventionally performed with double vascular access: arterial and venous. However, in patients with a good echogenic window it may be performed with venous access only and the procedure monitored by 2D-echocardiography and colour flow mapping. This should result in early ambulation and hospital discharge with reduced arterial complications. AIMS: To compare retrospectively the immediate results of percutaneous mitral valvuloplasty with the Inoue balloon in two groups of patients: Group I: venous access only (no arterial access, n = 102) and Group II: conventional double vascular access (arterial and venous access, n = 275). METHODS AND RESULTS: The baseline characteristics of the two groups were comparable for age, sex, clinical, echocardiographic, radiological and haemodynamic variables. The mitral valve area (Group I: 1.1 +/- 0.3 to 1.85 +/- 0.5 cm2 vs Group II: 1.05 +/- 0.2 to 1.85 +/- 0.5 cm2, P = ns) and transmitral gradient (Group I: 11 +/- 4 to 4.7 +/- 2 mmHg vs Group II: 12 +/- 4 to 4.8 +/- 2 mmHg, P = ns) before and after mitral valvuloplasty were not statistically different. A good immediate result, defined as mitral valve area > 1.5 cm2 and mean mitral gradient < 5 mmHg with mitral regurgitation < or = 2+ at the end of the procedure, was observed in 77% of the cases in the venous-only group and 79% in the double access group (P = ns). The incidence of severe mitral regurgitation (Grade III or IV) was not statistically significant. Procedural duration (71 +/- 24 min vs 109 +/- 26 min, P < 0.01), fluoroscopic time (12.5 +/- 5.5 min vs 18.5 +/- 6 min, P < 0.01) and hospital stay (2.8 +/- 1.5 days vs 4.8 +/- 2.6 days, P < 0.001) were significantly shorter in the venous-only group than in the conventional Inoue series. CONCLUSION: Single venous access balloon mitral valvuloplasty is as equally safe and effective as double vascular access. The additional advantages of single venous access are shorter procedural duration, fluoroscopic time and hospital stay. We recommend that it be performed by an experienced operator (minimum of 100 trans-septal punctures) in patients without major thoracic deformity and a good echogenic window.     

Femoral venous flow dynamics during intraperitoneal and preperitoneal laparoscopic insufflation

BACKGROUND: Laparoscopic herniorrhaphy may be performed using an intraperitoneal or a preperitoneal approach. Anecdotal and experimental evidence indicates that alterations in lower extremity venous flow, which occur during intraperitoneal laparoscopic insufflation, may be associated with an increased risk of deep vein thrombosis. However, no study has directly compared femoral venous flow during intraperitoneal insufflation with that during preperitoneal insufflation. METHOD: In eight consecutive patients undergoing laparoscopic herniorrhaphy under general anesthesia, flow through the common femoral vein was evaluated with B-mode and color flow duplex. Pre- and intraperitoneal pressures were standardized to 10 mm Hg, and respiratory tidal volumes were standardized to 10 cc/kg. Flow measurements were taken at end expiration. Flow through the common femoral vein was measured after induction of anesthesia, during intraperitoneal insufflation, during preperitoneal insufflation, and between insufflations to ensure return to baseline. RESULTS: All patients in the study were males. Their mean age was 59 years. Mean flow in the common femoral vein was essentially identical at baseline (138 ml/min) and during preperitoneal insufflation (135 ml/min). Alternatively, mean flow in the common femoral vein was significantly reduced during intraperitoneal insufflation (65 ml/min, p = 0.02). CONCLUSIONS: Flow in the common femoral vein is significantly reduced during intraperitoneal insufflation. However, flow in the common femoral vein is not affected by preperitoneal insufflation. These data suggest that laparoscopic preperitoneal inguinal hernia repair may pose as less a risk of thromboembolic complications than laparoscopic intraperitoneal inguinal hernia repair.     

A prospective, randomized trial comparing laparoscopic versus conventional techniques in colorectal cancer surgery: a preliminary report

BACKGROUND: Uncontrolled studies using laparoscopic techniques in colorectal surgery have not demonstrated clear advantages to these procedures compared with conventional ones, and surgeons are concerned about unusual early recurrences reported after laparoscopic colorectal cancer surgery. STUDY DESIGN: We conducted a prospective, randomized trial in one surgical department comparing laparoscopic (LAP) and conventional (CON) techniques in 109 patients undergoing bowel resection for colorectal cancers or polyps. Postoperatively, all patients underwent measurement of pulmonary function tests every 12 hours, and were treated identically on a highly controlled protocol with regard to analgesic administration, feeding, and postoperative care. RESULTS: Of the 55 patients assigned to LAP and 54 to the CON group, there were 42 and 38 with cancer, respectively (the other patients had large adenomas). Overall recovery of 80% of forced expiratory volume in 1 second and forced vital capacity was a median of 3 days for LAP and 6.0 days for CON (p = 0.01). LAP patients used significantly less morphine than CON patients up to the second day after surgery (0.78 +/- 0.32 versus 0.92 +/- 0.34 mg/kg per day, p = 0.02). Flatus returned a median of 3.0 days after LAP versus 4.0 days after CON surgery (p = 0.006). Tumor margins were clear in all patients. After a median followup of 1.5 years (LAP) and 1.7 years (CON), there were no port site recurrences in the LAP group. Seven cancer-related deaths have occurred (three in the LAP group, four in the CON group). CONCLUSIONS: Within this prospective, randomized trial, laparoscopic techniques were as safe as conventional surgical techniques and offered a faster recovery of pulmonary and gastrointestinal function compared with conventional surgery for selected patients undergoing large bowel resection for cancer or polyps. There were no apparent shortterm oncologic disadvantages. Longer followup is needed to fully assess oncologic outcomes.     

Postoperative pain and fatigue after laparoscopic or conventional colorectal resections. A prospective randomized trial

BACKGROUND: Conventional colorectal resections are associated with severe postoperative pain and prolonged fatigue. The laparoscopic approach to colorectal tumors may result in less pain as well as less fatigue, and may improve postoperative recovery after colorectal resections. METHODS: Sixty patients were included into a prospective randomized trial to determine the influence of laparoscopic (n = 30) or conventional (n = 30) resection of colorectal tumors on postoperative pain and fatigue. Major endpoints of the study were dose of morphine sulfate during patient-controlled analgesia (PCA), visual analog scale for pain while coughing (VASC), and visual analogue scale for fatigue (VASF). Efficacy of pain medication was assessed by visual analogue score at rest (VASR). RESULTS: Preoperative age, sex, stage, and localization of tumors were comparable in both groups. The PCA dose of morphine given immediately after surgery until postoperative day 4 was higher in the conventional group (median, 1.37 mg/kg; 5-95 percentile 0.71-2. 46 mg/kg) than the laparoscopic group (0.78 mg/kg; 0.24-2.38 mg/kg, p < 0.01). Postoperative VASR was comparable between both groups, but VASC was higher from the first to the seventh postoperative day (p < 0.01). Postoperative fatigue was higher after conventional than after laparoscopic surgery from the second to the seventh day (p < 0. 05). CONCLUSIONS: This study confirms that analgetic requirements are lower and pain is less intense after laparoscopic than after conventional colorectal resection. Patients also experience less fatigue after minimal invasive surgery. Because of these differences, the duration of recovery is shortened, and the postoperative quality of life is improved after laparoscopic colorectal resections.     

Skeletal muscle function and its relation to exercise tolerance in chronic heart failure

OBJECTIVES: This study sought to define the relation between muscle function and bulk in chronic heart failure (HF) and to explore the association between muscle function and bulk and exercise capacity. BACKGROUND: Skeletal muscle abnormalities have been postulated as determinants of exercise capacity in chronic HF. Previously, muscle function in chronic HF has been evaluated in relatively small numbers of patients and with variable results, with little account being taken of the effects of muscle wasting. METHODS: One hundred male patients with chronic HF and 31 healthy male control subjects were studied. They were matched for age (59.0 +/- 1.0 vs. 58.7 +/- 1.7 years [mean +/- SEM]) and body mass index (26.6 +/- 0.4 vs. 26.3 +/- 0.7 kg/m2). We assessed maximal treadmill oxygen consumption (VO2), quadriceps maximal isometric strength, fatigue (20-min protocol, expressed in baseline maximal strength) and computed tomographic cross-sectional area (CSA) at midthigh. RESULTS: Peak VO2 was lower in patients (18.0 +/- 0.6 vs. 33.3 +/- 1.4 ml/min per kg, p < 0.0001), although both groups achieved a similar respiratory exchange ratio at peak exercise (1.15 +/- 0.01 vs. 1.19 +/- 0.03, p = 0.13). Quadriceps (582 vs. 652 cm2, p < 0.05) and total leg muscle CSA (1,153 vs. 1,304 cm2, p < 0.005) were lower in patients with chronic HF. Patients were weaker than control subjects (357 +/- 12 vs. 434 +/- 18 N, p < 0.005) and also exhibited greater fatigue at 20 min (79.1% vs. 92.1% of baseline value, p < 0.0001). After correcting strength for quadriceps CSA, significant differences persisted (5.9 +/- 0.2 vs. 7.0 +/- 0.3 N/cm2, p < 0.005), indicating reduced strength per unit muscle. In patients, but not control subjects, muscle CSA significantly correlated with peak absolute VO2 (R = 0.66, p < 0.0001) and is an independent predictor of peak absolute VO2. CONCLUSIONS: Patients with chronic HF have reduced quadriceps maximal isometric strength. This weakness occurs as a result of both quantitative and qualitative abnormalities of the muscle. With increasing exercise limitation there is increasing muscle weakness. This progressive weakness occurs predominantly as a result of loss of quadriceps bulk. In patients, this muscular atrophy becomes a major determinant of exercise capacity.     

Efficacy of dead-space washout in mechanically ventilated premature newborns

The prosthetic dead space makes a significant contribution to the total dead space in low-birth-weight premature newborns receiving artificial ventilation in response to respiratory distress. Use of an endotracheal tube with capillaries molded into the tube wall enables washout of the dead space without insertion of a tracheal catheter. In 10 premature newborns (mean gestational age, 27.5 +/- 2.2 wk; mean weight, 890 +/- 260 g) receiving continuous positive-pressure ventilation (Paw = 12.7 +/- 1.8 cm H2O; FIO2 = 39 +/- 17%), tracheal gas insufflation (TGI) for CO2 washout was conducted using this technique. The flow of tracheal insufflation (0.5 L/min) was derived from the inspiratory line of the ventilator circuit and blown into the trachea. Intratracheal pressures showed little or no TGI-related modification ( < 1 cm H2O). A control system enabled TGI discontinuation in the event of a pressure rise. At constant ventilation pressure, PaCO2 decreased by 12.1 +/- 5.9 mm Hg (delta PaCO2 = -26 +/- 12%) under TGI, whereas PaO2 remained unchanged. While maintaining PaCO2 constant, peak inspiratory pressure (PIP) was decreased by 5.4 +/- 1.7 cm H2O (delta PIP = -22.0 +/- 8.3%). TGI showed immediate efficacy (PCO2 reduction of at least 5 mm Hg) in nine of the 10 newborns who then received chronic TGI (14 to 138 h). TGI appears to be an effective method, suitable for long-term clinical application, enabling a reduction in the aggressive nature of conventional ventilation.     

Quantitative assessment of the operative results after extended myectomy and surgical reconstruction of the subvalvular mitral apparatus in hypertrophic obstructive cardiomyopathy using dynamic three-dimensional transesophageal echocardiography

OBJECTIVES: The aim of this study was to examine the value of dynamic three-dimensional (3D) transesophageal echocardiography (TEE) for the postoperative evaluation after extended myectomy and surgical reconstruction of the subvalvular mitral valve apparatus in patients with hypertrophic obstructive cardiomyopathy (HOCM). BACKGROUND: Two-dimensional imaging techniques such as echocardiography, computed tomography and magnetic resonance imaging have not been able to precisely quantify the effects of surgical therapy on the morphology of the left ventricular outflow tract (LVOT). METHODS: Multiplane TEE with 3D reconstruction was performed in 11 patients before and after the operation and in 16 normal control subjects for comparison. The preoperative maximal systolic pressure gradient in the LVOT was 69 +/- 59 mm Hg. The following variables were measured within the dynamic 3D data set: depth, width, length and cross-sectional area (CSA) gain caused by the myectomy trough, minimal CSA of the LVOT at each time point and its cyclic changes and maximal mitral leaflet deviation during systole. RESULTS: Functional class improved from 3.0 +/- 0.2 before the operation to 1.5 +/- 0.6 after it. The maximal systolic pressure gradient in the outflow tract decreased to 26 +/- 21 mm Hg postoperatively (p < 0.001). Minimal CSA of the outflow tract increased from 1.1 +/- 1.2 to 3.8 +/- 1.9 cm2 postoperatively (p < 0.001), similar to the value of the control group (4.2 +/- 1.5 cm2, p = NS). The area gain due to the myectomy trough was 1.3 +/- 1.0 cm2, corresponding to 48 +/- 12% of the total operative area difference. Maximal systolic depth of the myectomy was 7 +/- 2 mm, maximal width was 20 +/- 8 mm and length was 28 +/- 7 mm. Maximal deviation of the mitral leaflets fell from 15 +/- 7 to 6 +/- 7 mm postoperatively (p < 0.01). In five patients mass measurements of the intracavitary portion of the papillary muscle (PM) revealed an increase from 7.3 +/- 1.0 to 12.1 +/- 2.5 g due to surgical mobilization of PMs (p < 0.01). CONCLUSIONS: 3D TEE quantifies the differences in outflow tract morphology before and after surgery for HOCM. This technique may have an impact on the planning of operative interventions and allow for the evaluation of its results.     

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.     

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.     

Consistency of response to sumatriptan nasal spray across patient subgroups and migraine types

Shoulder pain (SP) is frequently mentioned in recent literature following laparoscopic operations. In the literature, many causes have been declared to explain shoulder pain after CO2 insufflation, such as direct peritoneal irritation of the CO2 gas, excessive traction of the triangular ligament, and overstretching of the diaphragmatic muscle fibers due to the high rate of insufflation. This study was planned as multicentric, and 76 patients, aged between 35 to 45, were entered into the study. They were all selected by a randomized sampling method, with equal numbers of men and women, to achieve true evaluation. The low flow-rate (LFR) group was insufflated with 2.5 L/min and the high flow-rate (HFR) group with 7.5 L/min. All cases were evaluated by subjective pain classification on postoperative day 3. According to the subjective pain scale method, shoulder pain average was 23.9+/-3.1 in the LFR group and 55.4+/-6.5 in the HFR group. The difference between these groups was significant (p > 0.01). There is no significant difference for the operation time (LFR%: 64+/-15 minutes, HFR: 61+/-20 minutes, p > 0.05). Our results suggest that there is a significant statistical relation between the postoperative shoulder pain levels and increased insufflation rates. For this reason, low insufflation rate significantly reduces the shoulder pain but does not increase the operation time. Therefore, a low insufflation rate should be applied in all cases for patients' comfort and safety.     

Embryogenesis and functional development of the chick''s basilar papilla

BACKGROUND: After laparoscopy with carbon dioxide (CO2) insufflation early postoperative recovery is often complicated with drowsiness and postoperative nausea and vomiting (PONV). METHODS: 25 ASA I-II patients undergoing elective laparoscopic cholecystectomy under standardized anaesthesia were studied in a randomized, prospective study. The conventional CO2 pneumoperitoneum was compared with the mechanical abdominal wall lift (AWL) method with minimal CO2 insufflation with special reference to postoperative recovery. RESULTS: Postoperative drowsiness was of a significantly longer duration with the conventional method (p < 0.001) compared with the AWL technique. There was a positive correlation with the total amount of CO2 used and the duration of drowsiness (r = 0.75, p < 0.01). PONV was seen significantly more often in patients with CO2 insufflation of more than 121 (p < 0.05). CONCLUSIONS: Avoiding excessive CO2 is beneficial for smoother and more uneventful recovery after laparoscopic cholecystectomy.     

Continuous low-flow tracheal gas insufflation during partial liquid ventilation in rabbits

BACKGROUND: Both partial liquid ventilation (PLV) and tracheal gas insufflation are novel techniques for mechanical ventilation. In this study we examined whether PLV superimposed by continuous low-flow tracheal gas insufflation (TGI) offers any advantage to the blood gases and lung mechanics in normal-lung rabbits compared to the use of PLV only. METHODS: Eighteen anesthetized, paralyzed and mechanically ventilated rabbits were used. After obtaining a baseline PaCO2 value between 29 and 39 mmHg (3.9 and 5.2 kPa), the animals were assigned to three equal groups according to the ventilation they received--A group: PLV superimposed by TGI; B group: PLV only; and C group: continuous mandatory ventilation (CMV) superimposed by TGI. Serial arterial blood gases, pH and lung mechanics were measured. RESULTS: The animals in each group were hemodynamically stable. In the case of the A group, PaO2 continuously increased, and PaCO2 stabilized around 40.8 +/- 5.5 mmHg (5.4 +/- 0.7 kPa, mean +/- SD, NS). In the B group, the tendency for PaO2 to increase was not as definite; PaCO2 continuously increased from 35.2 +/- 2.3 mmHg (4.7 +/- 0.3 kPa) to 56.3 +/- 12.7 mmHg (7.5 +/- 1.7 kPa, P < 0.05) at the end of the experiment. In the C group, PaO2 and PaCO2 were stable during the observation period. The superimposition of TGI on PLV did not decrease the airway pressures compared to PLV alone. CONCLUSION: In summary, continuous low-flow TGI superimposed on PLV can decrease and stabilize the PaCO2 elevation caused by the initiation of PLV.     

Preconditioning improves myocardial function and reflow, but not vasodilator reactivity, after ischaemia and reperfusion in anaesthetized dogs

1. The present study examines whether three cycles of brief coronary artery occlusion and reperfusion (i.e. ischaemic preconditioning; PC) can prevent vasodilator dysfunction and the impairment of myocardial reflow caused by prolonged ischaemia. Coronary blood flow, left ventricular dP/dt, systemic arterial blood pressure and heart rate were measured in open-chest anaesthetized dogs. 2. Sixty minute occlusion of the left circumflex coronary artery (LCx) and 60 min LCx reperfusion (ISC/REP; group 1) significantly reduced resting coronary blood flow (CBF, initial 29 +/- 3 mL/min; ISC/REP 20 +/- 3 mL/min, P < 0.05 vs initial) and increased coronary vascular resistance (CVR, initial 4.1 +/- 0.6 mmHg/min per mL; ISC/REP 5.8 +/- 1.0 mmHg/min per mL, P < 0.05 vs initial). By contrast CBF and CVR were not affected in dogs subjected to preconditioning before ischaemia (group 2: CBF, initial 24 +/- 4 mL/min; PC+ISC/REP 23 +/- 4 mL/min; CVR, initial 4.7 +/- 0.6 mmHg/min per mL; PC+ ISC/REP 5.3 +/- 1.0 mmHg/min per mL). These data suggest that ischaemic preconditioning prevents the ischaemia-induced impairment of myocardial reflow. 3. Ischaemia and reperfusion impaired coronary dilator responses to the endothelium-dependent dilator acetylcholine (delta CBF, after ISC/REP: 50 +/- 6% of initial) and the endothelium-independent dilator glyceryl trinitrate (delta CBF, ISC/REP: 46 +/- 6% of initial). Despite the improvement in reperfusion in the preconditioned group, there was no significant improvement in responses to acetylcholine (PC+ISC/REP 52 +/- 6% of initial) or glyceryl trinitrate (PC+ISC/REP 59 +/- 6% of initial) after ischaemia and reperfusion. 4. The reduction in left ventricular dP/dt after ischaemia and reperfusion was significantly smaller in the preconditioned group indicating a lower level of impairment of cardiac contractility. In addition, we confirmed that preconditioning caused a significant reduction in infarct size and a reduction in the release of lactate dehydrogenase indicating less cardiac injury. 5. These results suggest that although ischaemic preconditioning was able to improve both myocardial reperfusion and contractility, it was not able to preserve vasodilator function. Such a reduction in vasodilator reserve could prevent adequate myocardial perfusion under conditions of elevated oxygen demand.     

Effects of heat and moisture exchangers on minute ventilation, ventilatory drive, and work of breathing during pressure-support ventilation in acute respiratory failure

OBJECTIVES: To evaluate the effect of two commonly used heat and moisture exchangers on respiratory function and gas exchange in patients with acute respiratory failure during pressure-support ventilation. DESIGN: Prospective, randomized trial. SETTING: Intensive care unit of a university hospital. PATIENTS: Fourteen patients with moderate acute respiratory failure, receiving pressure-support ventilation. INTERVENTIONS: Patients were assigned randomly to two treatment groups, in which two different heat and moisture exchangers were used: Hygroster (DAR S.p.A., Mirandola, Italy) with higher deadspace and lower resistance (group 1, n = 7), and Hygrobac-S (DAR S.p.A.) with lower deadspace and higher resistance (group 2, n = 7). Patients were assessed at three pressure-support levels: a) baseline (10.3 +/- 2.4 cm H2O for group 1, 9.3 +/- 1.3 cm H2O for group 2); b) 5 cm H2O above baseline; and c) 5 cm H2O below baseline. Measurements obtained with the heat and moisture exchangers were compared with those values obtained using the standard heated hot water humidifier. MEASUREMENTS AND MAIN RESULTS: At baseline pressure-support ventilation, the insertion of both heat and moisture exchangers induced in all patients a significant increase in the following parameters: minute ventilation (12.4 +/- 3.2 to 15.0 +/- 2.6 L/min for group 1, and 11.8 +/- 3.6 to 14.2 +/- 3.5 L/min for group 2); static intrinsic positive end-expiratory pressure (2.9 +/- 2.0 to 5.1 +/- 3.2 cm H2O for group 1, and 2.9 +/- 1.7 to 5.5 +/- 3.0 cm H2O for group 2); ventilatory drive, expressed as P41 (2.7 +/- 2.0 to 5.2 +/- 4.0 cm H2O for group 1, and 3.3 +/- 2.0 to 5.3 +/- 3.0 cm H2O for group 2); and work of breathing, expressed as either power (8.8 +/- 9.4 to 14.5 +/- 10.3 joule/ min for group 1, and 10.5 +/- 7.4 to 16.6 +/- 11.0 joule/min for group 2) or work per liter of ventilation (0.6 +/- 0.6 to 1.0 +/- 0.7 joule/L for group 1, and 0.8 +/- 0.4 to 1.1 +/- 0.5 joule/L. for group 2). These increases also occurred when pressure-support ventilation was both above and below the baseline level, although at high pressure support the increase in work of breathing with heat and moisture exchangers was less evident. Gas exchange was unaffected by heat and moisture exchangers, as minute ventilation increased to compensate for the higher deadspace produced in the circuit by the insertion of heat and moisture exchangers. CONCLUSIONS: The tested heat and moisture exchangers should be used carefully in patients with acute respiratory failure during pressure-support ventilation, since these devices substantially increase minute ventilation, ventilatory drive, and work of breathing. However, an increase in pressure-support ventilation (5 to 10 cm H2O) may compensate for the increased work of breathing.     

Continuous spinal anesthesia vs. combined spinal-epidural anesthesia in emergency surgery. The combined spinal-epidural anesthesia technique does not offer an advantage of spinal anesthesia with a microcatheter

In this prospective study we investigated the efficacy of microcatheter spinal anaesthesia in comparison with a combined spinal-epidural technique in trauma patients. METHODS: After institutional approval 60 patients undergoing urgent lower-limb surgery randomly received either CSA (22 G Sprotte needle, 28 G nylon catheter) in group 1 or CSE (18 G Tuohy needle, 22 G epidural catheter and 25 G pencil-point needle) in group 2. An initial subarachnoid bolus of 2 ml of plain bupivacaine 0.5% was injected in both groups. Difficulties with the lumbar puncture or catheter insertion, the time required for performance of either technique and the onset of analgesia at T12 were documented. If analgesia did not reach T12 within 20 min, supplemental bupivacaine was injected either intrathecally or epidurally up to a maximum of 5 ml in the CSA group or 16 ml in the CSE group. RESULTS: The number of lumbar punctures (CSA: n = 1.8 +/- 1.5; CSE: n = 2.6 +/- 1.8; P = 0.05) and the incidence of technical problems (CSA: 13%, CSE: 47%; P = 0.012) was higher in the CSE group. In contrast to CSA, performance of CSE was more time consuming (CSA: 8 +/- 3 min, CSE: 15 +/- 8 min; P = 0.0003), and the total dose of local anaesthetics was higher in the CSE group (CSA: 3.2 +/- 1 ml, CSE: 9.7 +/- 5 ml; P < 0.0001). CONCLUSIONS: Because of the higher incidence of technical problems, more time was required for the performance of CSE. As a consequence, microcatheter CSA might be preferred over CSE in trauma patients.     

Favorable effects of oral maintenance digoxin therapy on left ventricular performance in normal subjects: echocardiographic study

Left ventricular performance was assessed with echocardiography in 10 normal subjects before and during maintenance therapy with digoxin (0.5 mg/day orally) in the basal state and after acute pressure loading with intravenously administered phenylephrine. During digoxin therapy, despite a decrease in mean heart rate of 5 beats/min in the basal state, mean left ventricular ejection fraction increased from 74 +/- 2 to 79 +/- 1 percent (standard error, P less than 0.03); percent shortening of a left ventricular minor dimension increased from 37 +/- 2 to 41 +/- 1 percent (P less than 0.04) and the mean rate of left ventricular dimension shortening increased from 5.66 +/- 0.22 to 6.31 +/- 0.23 cm/sec (P = 0.05). During acute pressure loading with phenylephrine there was no change in mean heart rate after digoxin and mean ejection fraction increased from 69 +/- 3 to 75 +/- 2 percent; mean percent shortening increased from 33 +/- 2 to 38 +/- 2 percent; mean rate of shortening increased from 5.46 +/- 0.32 to 6.48 +/- 0.33 cm/sec and mean normalized rate of shortening increased from 1.11 +/- 0.06 to 1.29 +/- 0.05 sec-1 (all P less than 0.01). In a few subjects the response to digoxin did not coincide with the mean data for the whole group. This variability was largely due to difficulties in exactly matching heart rate between the control and digoxin studies. These data (1) support the concept that long-term oral digoxin therapy exerts a positive inotropic effect on the normal left ventricle, and (2) demonstrate the usefulness of echocardiography in nonivasive assessment of the effects of drugs on left ventricular performance.     

Utility of transesophageal echocardiography and pulmonary artery catheterization during laparoscopic assisted abdominal aortic aneurysm repair

BACKGROUND: Advanced laparoscopic procedures are more commonly performed in elderly patients with cardiac disease. There has been limited data on the use of pulmonary artery catheters (PAC) and transesophageal echocardiography (TEE) to monitor hemodynamic changes. METHODS: We prospectively studied eight patients undergoing laparoscopic assisted abdominal aortic aneurysm repair. All patients had a PAC and all but one had an intraoperative TEE. Data included heart rate (HR), temperature (temp), pulmonary artery systolic (PAS) and diastolic (PAD) pressures, mean arterial pressure (MAP), central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP), cardiac index (CI), mixed venous oxygen saturation (MVO2), and oxygen extraction ratio (O2Ex) and was obtained prior to induction, during insufflation, after desufflation, during aortic cross-clamp, and at the end of the procedure. End diastolic area (EDA), a reflection of volume status, was measured on TEE. ANOVA was used for data analysis. RESULTS: No changes were noted in HR, temp, PAS, PCWP, CI, MVO2, and O2Ex. PAD and CVP were greater during insufflation compared with baseline and aortic cross-clamp without associated changes in EDA. MAP was higher at baseline compared with all other times during the procedure. CONCLUSIONS: Insufflation increased PAD and CVP. However, volume status as suggested by EDA and PCWP did not change. These data question the reliability of hemodynamic measurements obtained from the PAC during pneumoperitoneum and suggest that TEE may be sufficient for evaluation of volume status along with the added benefit of timely detection of ventricular wall motion abnormalities.     

Intimal hyperplasia thickness at follow-up is independent of stent size: a serial intravascular ultrasound study

The purpose of this study was to determine whether the thickness of the intimal hyperplasia (IH) layer that accumulates within Palmaz-Schatz stents is dependent on stent size. Intravascular ultrasound (IVUS) and quantitative angiographic (QCA) studies were performed after stent implantation and at follow-up (5.4 +/- 3.8 months) in 161 patients with 177 lesions treated with 221 Palmaz-Schatz stents. Stent and lumen cross-sectional area (CSA) were measured. IH CSA and thickness at follow-up were calculated and compared with stent CSA and circumference. Maximum IH CSA and thickness were measured at the smallest follow-up lumen CSA; mean IH CSA and thickness was averaged over the length of the stent. Maximum IH CSA measured 4.8 +/- 2.4 mm2, and mean IH CSA measured 2.8 +/- 2.2 mm2. Maximum IH thickness (at the smallest follow-up lumen CSA) measured 0.60 +/- 0.36 mm, and mean IH thickness (over the length of the stent) measured 0.30 +/- 0.19 mm. There was a weak, but significant correlation between mean and maximum IH CSA versus stent CSA (r = 0.215, p <0.0001 and r = 0.355, p <0.0001, respectively). However, there was no correlation between mean or maximum IH thickness versus stent CSA (r = 0.018, p = 0.643 and r = 0.056, p = 0.463, respectively) or stent circumference (r = 0.002, p = 0.956 and r = 0.069, p = 0.361, respectively). IH thickness was found to be independent of the stent size. This explains the known higher frequency of restenosis in smaller stents compared with larger stents.