Inspiratory and end-expiratory effects of lung recruitment in the prone position on dorsal lung aeration - new physiological insights in a secondary analysis of a randomised controlled study in post-cardiac surgery patients.

Background: Cardiac surgery produces dorso-basal atelectasis and ventilation/perfusion mismatch, associated with infection and prolonged intensive care. A postoperative lung volume recruitment manoeuvre to decrease the degree of atelectasis is routine. In patients with severe respiratory failure, prone positioning and recruitment manoeuvres may increase survival, oxygenation, or both. We compared the effects of lung recruitment in prone vs supine positions on dorsal inspiratory and end-expiratory lung aeration. Methods: In a prospective RCT, 30 post-cardiac surgery patients were randomly allocated to recruitment manoeuvres in the prone (n=15) or supine position (n=15). The primary endpoints were late dorsal inspiratory volume (arbitrary units [a.u.]) and left/right dorsal end-expiratory lung volume change (a.u.), prone vs supine after extubation, measured using electrical impedance tomography. Secondary outcomes included left/right dorsal inspiratory volumes (a.u.) and left/right dorsal end-expiratory lung volume change (a.u.) after prone recruitment and extubation. Results: The last part of dorsal end-inspiratory volume after extubation was higher after prone (49.1 a.u.; 95% confidence interval [CI], 37.4-60.6) vs supine recruitment (24.2 a.u.; 95% CI, 18.4-29.6; P=0.024). Improvement in left dorsal end-expiratory lung volume after extubation was higher after prone (382 a.u.; 95% CI, 261-502) vs supine recruitment (-71 a.u., 95% CI, -140 to -2; n=15; P<0.001). After prone recruitment, left vs right predominant end-expiratory dorsal lung volume change disappeared after extubation. However, both left and right end-expiratory volumes were higher in the prone group, after extubation. Conclusions: Recruitment in the prone position improves dorsal inspiratory and end-expiratory lung volumes after cardiac surgery. Clinical trial registration: NCT03009331.

Lung recruitment in the prone position after cardiac surgery: a randomised controlled study.

BACKGROUND: Atelectasis after cardiac surgery is common and promotes ventilation/perfusion mismatch, infection, and delayed discharge from critical care. Recruitment manoeuvres are often performed to reduce atelectasis. In severe respiratory failure, recruitment manoeuvres in the prone position may increase oxygenation, survival, or both. We compared the effects of recruitment manoeuvres in the prone vs supine position on lung aeration and oxygenation in cardiac surgical patients. METHODS: Subjects were randomised to recruitment manoeuvres (40 cm H2O peak inspiratory pressure and 20 cm H2O PEEP for 30 s) in either the prone or supine position after uncomplicated cardiac surgery. The co-primary endpoints were lung aeration (end-expiratory lung volume measured by electrical impedance tomography (arbitrary units [a.u.]) and lung oxygenation (ratio of arterial oxygen partial pressure to fractional inspired oxygen [Pao2/FiO2 ratio]). Secondary outcomes included postoperative oxygen requirement and adverse events. RESULTS: Thirty subjects (27% female; age, 48-81 yr) were recruited. Dorsal lung tidal volume was higher after prone recruitment manoeuvres (363 a.u.; 95% confidence intervals [CI], 283-443; n=15) after extubation, compared with supine recruitment manoeuvres (212 a.u.; 95% CI, 170-254; n=15; P<0.001). Prone recruitment manoeuvres increased dorsal end-expiratory lung volume by 724 a.u. (95% CI, 456-992) after extubation, compared with 163 a.u. decrease (95% CI, 73-252) after supine recruitment manoeuvres (P<0.001). The Pao2/FiO2 ratio after extubation was higher after prone recruitment manoeuvres (46.6; 95% CI, 40.7-53.0) compared with supine recruitment manoeuvres (39.3; 95% CI, 34.8-43.8; P=0.04). Oxygen therapy after extubation was shorter after prone (33 h [13]) vs supine recruitment manoeuvres (52 h [22]; P=0.01). No adverse events occurred. CONCLUSIONS: Recruitment manoeuvres in the prone position after cardiac surgery improve lung aeration and oxygenation. CLINICAL TRIAL REGISTRATION: NCT03009331.

The role of bone cement for the development of intraoperative hypotension and hypoxia and its impact on mortality in hemiarthroplasty for femoral neck fractures.

Background and purpose - The bone cement implantation syndrome characterized by hypotension and/or hypoxia is a well-known complication in cemented arthroplasty. We studied the incidence of hypotension and/or hypoxia in patients undergoing cemented or uncemented hemiarthroplasty for femoral neck fractures and evaluated whether bone cement was an independent risk factor for postoperative mortality.Patients and methods - In this retrospective cohort study, 1,095 patients from 2 hospitals undergoing hemiarthroplasty with (n = 986) and without (n = 109) bone cementation were included. Pre-, intra-, and postoperative data were obtained from electronic medical records. Each patient was classified for grade of hypotension and hypoxia during and after prosthesis insertion according to Donaldson's criteria (Grade 1, 2, 3). After adjustments for confounders, the hazard ratio (HR) for the use of bone cement on 1-year mortality was assessed.Results - The incidence of hypoxia and/or hypotension was higher in the cemented (28%) compared with the uncemented group (17%) (p = 0.003). The incidence of severe hypotension/hypoxia (grade 2 or 3) was 6.9% in the cemented, but not observed in the uncemented group. The use of bone cement was an independent risk factor for 1-year mortality (HR 1.9, 95% CI 1.3-2.7), when adjusted for confounders.Interpretation - The use of bone cement in hemiarthroplasty for femoral neck fractures increases the incidence of intraoperative hypoxia and/or hypotension and is an independent risk factor for postoperative 1-year mortality. Efforts should be made to identify patients at risk for BCIS and alternative strategies for the management of these patients should be considered.

Levosimendan or milrinone for right ventricular inotropic treatment?-A secondary analysis of a randomized trial.

BACKGROUND: The aim of the present study was to compare the effects of milrinone and levosimendan on right ventricular (RV) inotropy and lusitropy in patients after aortic valve replacement (AVR) for aortic stenosis, a procedure in which an abnormal postoperative RV function may be seen. METHODS: In a prospective, blinded trial, 31 patients were randomized to receive either milrinone (0.4 and 0.8 µg/kg/min, n = 16) or levosimendan (0.1 and 0.2 µg/kg/min, n = 15) after AVR for aortic stenosis. RV performance, afterload (pulmonary arterial elastance), RV strain, systolic (SR-S) and early diastolic (SR-E) strain rate were measured by pulmonary artery thermodilution catheterization and transoesophageal two-dimensional speckle tracking echocardiography. To circumvent the indirect effects of inodilator-induced hemodynamic changes on RV systolic and diastolic deformation, pulmonary arterial elastance, central venous pressure and heart rate were maintained constant by atrial pacing, plasma volume expansion with colloids and phenylephrine-induced vasoconstriction during treatment with the inotropes. RESULTS: A dose-dependent increase in stroke volume index and cardiac index by approximately 20% were seen with both agents at the highest doses, with no difference between groups (P = .792 and 0.744, respectively). In both groups, RV strain and SR-S dose-dependently increased by 20% and 15%-19%, respectively, at the highest doses (P = .742 and 0.259, respectively) with no difference between groups. SR-E improved by both agents 20%-24% at the highest dose with no difference between groups (P = .714). CONCLUSIONS: The direct RV inotropic and lusitropic effects of levosimendan and milrinone were comparable at clinically relevant infusion rates.

Inhaled prostacyclin for the prevention of increased pulmonary vascular resistance in cemented hip hemiarthroplasty-A randomised trial.

BACKGROUND: Bone cementation may cause pulmonary vasoconstriction and ventilation/perfusion abnormalities in patients undergoing cemented hip hemiarthroplasty. In this randomised trial, we tested the hypothesis that intra-operative inhalation of prostacyclin could attenuate the increase in pulmonary vascular resistance index (PVRI, primary endpoint) when compared to inhaled saline in this group of patients. METHODS: Twenty-two patients with displaced femoral neck fractures were allocated to receive inhaled aerosolised prostacyclin (20 ng/kg/min) (n = 11) or inhaled saline (NaCl, 9 mg/mL) (n = 11). All patients received total intravenous anaesthesia and were catheterised with radial and pulmonary artery fast response thermodilution catheters, for measurements of arterial and pulmonary arterial pressures, cardiac output, right ventricular ejection fraction and effective pulmonary arterial elastance. Haemodynamic measurements were performed after induction of anaesthesia, during surgery before and immediately after bone cementation and prosthesis insertion, 10 and 20 min after insertion and during skin closure. RESULTS: During the surgical procedure, PVRI increased both in the saline (44%, P < 0.001) and the prostacyclin (36%, P = 0.019) groups, with a less pronounced increase in the prostacyclin group (P = 0.031). Effective pulmonary arterial elastance increased both in the saline (44%, P < 0.001) and the prostacyclin groups (29%, P = 0.032), with a trend for a less pronounced increase in the prostacyclin group (P = 0.084). Right ventricular ejection fraction decreased significantly in both groups with no difference between the groups. CONCLUSION: Inhalation of prostacyclin attenuates the increase in pulmonary vascular resistance in patients undergoing cemented hip hemiarthroplasty and could potentially attenuate/prevent haemodynamic instability induced by an increase in right ventricular afterload seen in this procedure.

Pulmonary haemodynamics and right ventricular function in cemented vs uncemented total hip arthroplasty-A randomized trial.

BACKGROUND: Bone cement implantation syndrome (BCIS) is a feared complication in orthopaedic surgery with a huge impact on post-operative morbidity. In this randomized trial, we evaluated the effects of bone cement on pulmonary and systemic haemodynamics in patients receiving either cemented or uncemented hip arthroplasty for isolated femoral neck fracture. METHODS: Twenty-two patients were randomized to receive either cemented (n = 10) or uncemented (n = 12) total hip arthroplasty. Surgery was performed under total intravenous anaesthesia in the lateral position. All patients were catheterized with radial- and pulmonary artery catheters, for continuous measurements of mean arterial pressure (MAP), pulmonary arterial pressure (PAP), cardiac output, right ventricular (RV) end-diastolic volume (RVEDV) and RV ejection fraction (RVEF). Haemodynamic measurements and blood gas analyses were performed after induction of anaesthesia, during surgery before and immediately after bone cementation and prosthesis insertion, 10 and 20 minutes after insertion and during skin closure. RESULTS: Pulmonary vascular resistance index (PVRI) increased during and after prosthesis insertion by 45% and 20% in the cemented and uncemented group, respectively (P < 0.005). Systolic and mean PAP increased by 18% and 17% in the cemented group, which was not seen in the uncemented group (P < 0.001). There was a trend for a more pronounced fall in RVEF in the cemented group, while there were no differences in cardiac output or stroke volume between groups. CONCLUSION: The use of bone cement in total hip arthroplasty increases pulmonary vascular resistance and the afterload of the RV with potentially negative effects on RV performance.

Impact of trismus on health-related quality of life and mental health.

BACKGROUND: Trismus is a common symptom often related to the treatment for head and neck cancer and to temporomandibular disorders. The purpose of the present study was to measure the impact of trismus on health-related quality of life (HRQOL) and mental health in patients with head and neck cancer and temporomandibular disorder. METHODS: We used the criteria for trismus of maximum interincisal opening (MIO) ≤35 mm and the study subjects responded to the following instruments: the Gothenburg Trismus Questionnaire (GTQ), the Short-Form 36 Health Survey (SF-36), and the Hospital Anxiety and Depression Scale (HADS). The study also comprised an age-matched and sex-matched control group without trismus. RESULTS: Patients with trismus reported significantly more dysfunction in all GTQ domains and more facial pain compared to the control group. The patients with head and neck cancer and trismus scored significantly lower on all SF-36 domains except general health compared to the control group, and the patients with temporomandibular disorder with trismus scored significantly lower in 3 of the 8 domains in SF-36. According to the HADS, a greater proportion of patients with head and neck cancer with trismus displayed more depression compared to the control group. CONCLUSION: The results showed that trismus is associated with a significant impact on HRQOL and that patients with trismus should be approached in a holistic way with respect for the underlying cause, treating not only the physical aspects of trismus but also addressing the patients' mental health.

The relative contribution of prosthetic gradients, systemic arterial pressure, and pulse pressure to the left ventricular pressure in patients with aortic prosthetic valves.

AIMS: aortic valve replacement (AVR) in patients with aortic stenosis reduces the left ventricular (LV) pressure and the LV mass. However, residual LV hypertrophy at follow-up is a common finding with negative prognostic impact. In the present study, we investigate the contribution of the prosthesis (size, type, and gradients) and the load opposed by the arterial system to the mean LV pressure (MLVP). METHODS AND RESULTS: twenty-five patients with a bileaflet mechanical (n = 12, size 19-27) or stented biological (size 21-25) valve were included. After weaning from bypass, continuous Doppler recordings (transoesophageal transducer) and simultaneous LV and aortic pressure measurements were performed (high-fidelity catheters). The mean prosthesis gradients with catheter or Doppler were moderately correlated to MLVP (R(2) = 0.40 and 0.34, P = 0.002 and <0.0001). In a multiple regression model, the relationship between MLVP and prosthesis gradient, mean blood pressure, and pulse pressure was strong for both mechanical and biological valves. Using catheter prosthesis gradients, we could explain 97% of the variability in MLVP and when using Doppler gradients 91%. CONCLUSION: in the present study of patients with aortic prosthetic valves, we demonstrate the importance of the load opposed by the arterial system for the LV pressure. Our findings suggest that the MLVP can be estimated from easily obtainable Doppler data and blood pressure measurements. In analysing predictors of LV mass regression, morbidity, and mortality following AVR, the equations might be of interest.

Doppler-catheter discrepancies in patients with bileaflet mechanical prostheses or bioprostheses in the aortic valve position.

The aims of the present study were to investigate in vivo Doppler-catheter discrepancies in aortic bileaflet mechanical and stented biologic valves and evaluate whether these can be predicted using Doppler echocardiography. Results of in vitro studies of bileaflet mechanical valves suggested overestimation using Doppler gradients. Findings in stented biologic valves were conflicting. Patients who underwent valve replacement with a St. Jude Medical mechanical (n = 14, size 19 to 29) or a St. Jude Medical Biocor (Biocor, n = 13, size 21 to 25) valve were included. Simultaneous continuous Doppler recordings (transesophageal transducer) and left ventricular and aortic pressure measurements were performed using high-fidelity catheters. Gradients after pressure recovery were predicted from Doppler using a validated equation. Doppler overestimated catheter gradients in both the mechanical and Biocor. Mean Doppler catheter differences for the mechanical/Biocor were for mean gradients of 4 +/- 3 (SD; p = 0.002)/6 +/- 4 mm Hg (p = 0.002). There was a strong relation between catheter and Doppler gradients (r = 0.85 to 0.92). Doppler catheter discrepancy as a percentage of the Doppler mean gradient for the mechanical was median 41% (range -30% to 76%) and for the Biocor was median 35% (range -7% to 75%). The catheter-Doppler discrepancy was not significant using the predicted net gradient from Doppler. In conclusion, this was the first in vivo investigation of prosthetic valves using simultaneous Doppler and high-fidelity catheters. Doppler overestimated catheter gradients in both mechanical and stented biologic valves. However, the discrepancy can be predicted considering pressure recovery in the aorta.

Effects of levosimendan on left ventricular relaxation and early filling at maintained preload and afterload conditions after aortic valve replacement for aortic stenosis.

BACKGROUND: We determined the effects of levosimendan, a calcium sensitizer, on left ventricular (LV) diastolic function in patients with LV hypertrophy. METHODS AND RESULTS: In this prospective, randomized, blinded study, 23 patients received either levosimendan (0.1 and 0.2 microg x kg(-1) x min(-1); n=12) or placebo (n=11) after aortic valve replacement for aortic stenosis. The effects on LV performance, dimensions, filling patterns, and isovolumic relaxation time, as well as systemic hemodynamics, were assessed by pulmonary artery thermodilution catheterization and transesophageal 2-dimensional Doppler echocardiography. To circumvent the confounding effects of the levosimendan-induced hemodynamic changes on Doppler echocardiographic indexes of LV early relaxation, heart rate and mean arterial and central venous pressures were kept constant during levosimendan/placebo infusion by atrial pacing, vasopressor, and colloid infusions. In the levosimendan group, dose-dependent increases in cardiac output (28%; P<0.001) and stroke volume (26%; P<0.001) and a decrease in systemic vascular resistance (-22%; P<0.001) were observed. There was a trend for an increase in LV ejection fraction (12%; P=0.058) with levosimendan. There were no significant differences in systolic, diastolic arterial, or LV filling pressures or LV end-diastolic area between the 2 groups. Isovolumic relaxation time decreased (-23%; P<0.001), as did the deceleration slope of early diastolic filling (-45%; P<0.01), whereas peak early diastolic filling velocity (16%, P<0.01) and peak late diastolic filling velocity (15%; P<0.001) increased after levosimendan compared with placebo. CONCLUSIONS: Levosimendan, in addition to its inotropic effects, exerts a direct positive lusitropic effect in patients with LV hypertrophy as it shortens isovolumic relaxation time and improves LV filling.

Reduced intrathoracic blood volume and left and right ventricular dimensions in patients with severe emphysema: an MRI study.

BACKGROUND: Left ventricular (LV) filling is impaired in patients with severe emphysema manifesting in small end-diastolic dimensions. We hypothesized that the hyperinflated lungs of these patients with high intrinsic positive end-expiratory pressure will decrease intrathoracic blood volume (ITBV) and ventricular preload. We therefore measured ITBV, and LV and right ventricular (RV) dimensions and function using MRI techniques in patients with severe emphysema. METHODS: Patients with severe emphysema (n = 13) and matched healthy volunteers (n = 11) were included. The magnetic resonance (MR) examination consisted of three parts: (1) evaluation of RV and LV dimensions and function and interventricular septum curvature using cine MRI; (2) quantification of aortic flow using MR phase velocity mapping; and (3) calculation of the cardiopulmonary peak transit time (PTT) from the pulmonary artery to the ascending aorta using contrast-enhanced, time-resolved, two-dimensional MR angiography. RESULTS: There were no differences between the groups regarding age, height, or weight. In the emphysema patients, ITBV index (- 35%), LV end-diastolic volume index (LVEDVI) [- 21%], RV end-diastolic volume index (- 20%), cardiac index (- 22%), and stroke volume index (SVI) [- 40%] were lower compared to control subjects. LV and RV end-systolic volumes, LV wall mass, septal curvature, and PTT did not differ between the groups. LVEDVI (r = 0.83) as well as SVI (r = 0.82) correlated closely to ITBV index. SVI correlated closely to LVEDVI (r = 0.84). CONCLUSIONS: LV and RV performance is impaired in patients with severe emphysema because of small end-diastolic dimensions. One possible explanation for the decreased biventricular preload in these patients is intrathoracic hypovolemia caused by hyperinflated lungs.

Left ventricular performance and dimensions in patients with severe emphysema.

BACKGROUND: Concomitant heart dysfunction during the course of chronic obstructive pulmonary disease is well recognized. The prevailing view is that mainly the right side of the heart is involved. We evaluated left ventricular (LV) function and dimensions in patients with severe emphysema. METHODS: Patients with severe emphysema undergoing lung volume reduction surgery were studied after anesthesia induction (n = 10). Non-emphysematous patients scheduled for lobectomy served as controls (n = 10). LV dimensions were measured with patients in the supine position by transesophageal two-dimensional echocardiography and systemic hemodynamics by a pulmonary artery thermodilution catheter, before and during central blood volume expansion by passive leg elevation. RESULTS: Baseline cardiac index (-25%), stroke volume index (SVI, -32%) stroke work index (-34%) and LV end-diastolic area index (EDAI, -33%) were significantly (P < 0.001) lower in the emphysema group. Passive leg elevation increased SVI and LV area ejection fraction more in the emphysema group than in controls (P < 0.05). The DeltaSVI/Delta pulmonary capillary wedge pressure and the DeltaSVI/DeltaEDAI relationships were significantly (P < 0.05) higher in the emphysema group compared to controls (2.2 +/- 0.71 vs 0.6 +/- 0.2 mL/mm Hg x m2 and 5.8 +/- 0.89 vs 2.8 +/- 0.8 mL/cm2 x m2, respectively). Preload-recruitable stroke work (Deltastroke work index/DeltaEDAI), a load-independent index of systolic LV function, did not differ between the two groups. CONCLUSION: The LV in patients with severe emphysema is hypovolemic, and operates on a steeper portion of the LV function curve, while indices of systolic function are not significantly impaired compared to non-emphysematous controls.

Autoregulation of human jejunal mucosal perfusion during cardiopulmonary bypass.

Animal studies have suggested that autoregulation of intestinal blood flow is severely impaired during cardiopulmonary bypass (CPB). We investigated the jejunal mucosal capacity to autoregulate perfusion during nonpulsatile CPB (34 degrees C) in 10 patients undergoing elective cardiac surgery. Changes in mean arterial blood pressure (MAP) were induced by altering the CPB flow rate randomly for periods of 3 min from 2.4 L/min/m2 to either 1.8 or 3.0 L/min/m2. Jejunal mucosal perfusion (JMP) was continuously recorded by laser Doppler flowmetry. A typical pattern of flow motion (vasomotion) was recorded in all patients during CPB. Variations in CPB flow rates caused no significant changes in mean JMP, jejunal mucosal hematocrit, or red blood cell velocity within a range of MAP from 50 +/- 15 to 74 +/- 16 mm Hg. The vasomotion frequency and amplitude was positively correlated with CPB flow rate. IV injections of prostacyclin (10 microg, Flolan) blunted vasomotion and increased JMP from 192 +/- 53 to 277 +/- 70 (P < 0.05) perfusion units despite a reduction in MAP from 59 +/- 12 to 45 +/- 10 mm Hg (P < 0.05). Prostacyclin-induced vasodilation resulted in loss of mucosal autoregulation (pressure-dependent perfusion). We conclude that autoregulation of intestinal mucosal perfusion is maintained during CPB in humans.

Thoracic epidural versus intravenous patient-controlled analgesia after cardiac surgery: a randomized controlled trial on length of hospital stay and patient-perceived quality of recovery.

BACKGROUND: Perioperative thoracic epidural analgesia reduces stress response and pain scores and may improve outcome after cardiac surgery. This prospective, randomized trial was designed to compare the effectiveness of patient-controlled thoracic epidural analgesia with patient-controlled analgesia with intravenous morphine on postoperative hospital length of stay and patients' perception of their quality of recovery after cardiac surgery. METHODS: One hundred thirteen patients undergoing elective cardiac surgery were randomly assigned to receive either combined thoracic epidural analgesia and general anesthesia followed by patient-controlled thoracic epidural analgesia or general anesthesia followed by to patient-controlled analgesia with intravenous morphine. Postoperative length of stay, time to eligibility for hospital discharge, pain and sedation scores, degree of ambulation, lung volumes, and organ morbidities were evaluated. A validated quality of recovery score was used to measure postoperative health status. RESULTS: Length of stay and time to eligibility for hospital discharge were similar between the groups. Study groups differed neither in postoperative global quality of recovery score nor in five dimensions of quality of recovery score. Time to extubation was shorter (P < 0.001) and consumption of anesthetics was lower in the patient-controlled thoracic epidural analgesia group. Pain relief, degree of sedation, ambulation, and lung volumes were similar between the study groups. There was a trend for lower incidences of pneumonia (P = 0.085) and confusion (P = 0.10) in the patient-controlled thoracic epidural analgesia group, whereas cardiac, renal, and neurologic outcomes were similar between the groups. CONCLUSIONS: In elective cardiac surgery, thoracic epidural analgesia combined with general anesthesia followed by patient-controlled thoracic epidural analgesia offers no major advantage with respect to hospital length of stay, quality of recovery, or morbidity when compared with general anesthesia alone followed by to patient-controlled analgesia with intravenous morphine.

Estimation of functional residual capacity at the bedside using standard monitoring equipment: a modified nitrogen washout/washin technique requiring a small change of the inspired oxygen fraction.

We developed a modified nitrogen washin/washout technique based on standard monitors using inspiratory and end-tidal gas concentration values for functional residual capacity (FRC) measurements in patients with acute respiratory failure (ARF). For validation we used an oxygen-consuming lung model ventilated with an inspiratory oxygen fraction (Fio(2)) between 0.3 and 1.0. The respiratory quotient of the lung model was varied between 0.7 and 1.0. Measurements were performed changing Fio(2) with fractions of 0.1, 0.2, and 0.3. In 28 patients with ARF, duplicate measurements were performed. In the lung model, an Fio(2) change of 0.1 resulted in a value of 103 +/- 5% of the reference FRC value of the lung model, and the precision was equally good up to an Fio(2) of 1.0 with a value of 103 +/- 7%. In the patients, duplicate measurements showed a bias of -5 mL with a 95% confidence interval [-38; 29 mL ]. A comparison of a change in Fio(2) of 0.1 with 0.3 showed a bias of -9 mL and limits of agreement of [-365; 347 mL]. This study shows good precision of FRC measurements with standard monitors using a change in Fio(2) of only 0.1. Measurements can be performed with equal precision up to an Fio(2) of 1.0.

Recombinant activated factor VII in the management of life-threatening bleeding in cardiac surgery.

OBJECTIVE: Massive perioperative bleeding is a potential complication of cardiac surgery, and may persist despite conventional interventions. RFVIIa is being increasingly used as additional therapy, and the aim of the present study was to describe our experience with rFVIIa in the management of life-threatening bleeding in adult cardiac surgery. METHODS: Retrospective chart review of 24 patients undergoing a variety of cardiac procedures was performed at Sahlgrenska University Hospital between January and August 2004. The patients developed life-threatening bleeding during or after surgery despite conventional medical therapy and transfusion of blood products, and received rFVIIa as additional therapy. RESULTS: RFVIIa was administered as a median bolus dose of 60 microg/kg. Nineteen patients received one dose of rFVIIa; the bleeding stopped or decreased in 18 of them. Five patients received repeated doses of rFVIIa. Fifteen patients were reexplored due to massive postoperative bleeding or cardiac tamponade and a surgical source of bleeding was identified in six of these patients. A statistically significant reduction in chest drain losses after administration of rFVIIa was demonstrated. No adverse reactions were noted. CONCLUSIONS: RFVIIa was successfully used as an additional therapy both during and after cardiac surgery, when bleeding was refractory to conventional methods. Bleeding stopped eventually in all patients and none of the patients exsanguinated.

Effectiveness and side effects of closed and open suctioning: an experimental evaluation.

OBJECTIVE: To compare the effectiveness of closed system suctioning (CSS) and open system suctioning (OSS) and the side effects on gas exchange and haemodynamics, during pressure-controlled ventilation (PCV) or continuous positive airway pressure (CPAP). DESIGN: Bench test and porcine lung injury model. PARTICIPANTS: Twelve bronchoalveolar saline-lavaged pigs. SETTING: Research laboratory in a university hospital. INTERVENTIONS: In a mechanical lung, the efficacy of OSS and CSS with 12 and 14 Fr catheters were compared during volume-control ventilation, PCV, CPAP 0 or 10 cmH(2)O by weighing the suction system before and after aspirating gel in a transparent trachea. Side effects were evaluated in the animals with the same ventilator settings during suctioning of 5, 10 or 20 s duration. MEASUREMENTS AND RESULTS: Suctioning with 12 and 14 Fr catheters was significantly more efficient with OSS (1.9+/-0.1, 2.8+/-0.9 g) and with CSS during CPAP 0 cmH(2)O (1.8+/-0.2, 4.2+/-0.5 g) as compared to CSS during PCV (0.2+/-0.2, 0.8+/-0.3 g) or CPAP 10 cmH(2)O (0.0+/-0.1, 0.7+/-0.4 g), p<0.01 (means +/- SD). OSS and CSS at CPAP 0 cmH(2)O resulted in a marked decrease in SpO(2), mixed venous oxygen saturation and tracheal pressure, p<0.001, but the side effects were considerably fewer during CSS with PCV and CPAP 10 cmH(2)O, p<0.05. CONCLUSIONS: Irrespective of catheter size, OSS and CSS during CPAP 0 cmH(2)O were markedly more effective than CSS during PCV and CPAP 10 cmH(2)O but had worse side effects. However, the side effects lasted less than 5 min in this animal model. Suctioning should be performed effectively when absolutely indicated and the side effects handled adequately.

Effects of lung volume reduction surgery on left ventricular diastolic filling and dimensions in patients with severe emphysema.

STUDY OBJECTIVES: Data on the influence of lung volume reduction surgery (LVRS) on cardiac function and hemodynamics are scarce and controversial. Previous studies have focused mainly on right ventricular function and pulmonary hemodynamics. Here, we evaluated the effects of LVRS on left ventricular (LV) end-diastolic filling pattern, dimensions, stiffness, and performance, as well as pulmonary and systemic hemodynamics. DESIGN: A prospective, open, controlled study. PATIENTS: Patients with severe emphysema undergoing LVRS (10 patients). Patients scheduled for pulmonary lobectomy due to carcinoma (ie, the lobectomy group) served as control subjects (10 patients). MEASUREMENTS: LV dimensions and mitral flow velocities were measured by transesophageal, two-dimensional, Doppler echocardiography, and central hemodynamics were measured by a pulmonary artery thermodilution catheter. Measurements were performed during anesthesia in the supine position, before and after surgery, without and with passive leg elevation. RESULTS: Baseline cardiac index (CI) [- 21%], stroke volume index (SVI) [- 31%], stroke work index (SWI) [- 26%], and LV end-diastolic area index (EDAI) [- 15%] were significantly (p < 0.001) lower, whereas LV end-diastolic stiffness (LVEDS) did not differ in the LVRS group compared to the lobectomy group. The time from peak early diastolic filling to zero flow (E-dec time) [58%] and the deceleration slope of early diastolic filling (E-dec slope) [45%] were significantly higher (p < 0.01), whereas peak early diastolic filling velocity (E-max) [- 31%; p < 0.01] and the proportion of E-max vs peak late diastolic filling velocity (A-max) [ie, the E/A ratio] (- 27%; p < 0.001) were significantly lower compared to the lobectomy group. LVRS significantly increased CI (40%; p < 0.001), SVI (34%; p < 0.001), SWI (58%; p < 0.001), LV EDAI (18%; p < 0.001), E-max (44%; p < 0.01), A-max (15%; p < 0.05) and E/A ratio (28%; p < 0.01), decreased E-dec time (- 31%; p < 0.05) and E-dec slope (- 98%; p < 0.01), and had no effect on LVEDS. In the lobectomy group, surgery affected none of these variables. CONCLUSIONS: LV function is impaired in patients with severe emphysema due to small end-diastolic dimensions. LVRS increases LV end-diastolic dimensions and filling, and improves LV function.

The effects of isoflurane-induced electroencephalographic burst suppression on cerebral blood flow velocity and cerebral oxygen extraction during cardiopulmonary bypass.

UNLABELLED: We investigated the effects of isoflurane-induced burst suppression, monitored with electroencephalography (EEG), on cerebral blood flow velocity (CBFV), cerebral oxygen extraction (COE), and autoregulation in 16 patients undergoing cardiac surgery. The experimental procedure was performed during nonpulsatile cardiopulmonary bypass (CPB) with mild hypothermia (32 degrees C) in fentanyl-anesthestized patients. Middle cerebral artery transcranial Doppler flow velocity, right jugular vein bulb oxygen saturation, and jugular venous pressure (JVP) were continuously measured. Autoregulation was tested during changes in mean arterial blood pressure (MAP) within a range of 40-80 mm Hg, induced by sodium nitroprusside and phenylephrine before (control) and during additional isoflurane administration to an EEG burst-suppression level of 6-9/min. Isoflurane induced a 27% decrease in CBFV (P < 0.05) and a 13% decrease in COE (P < 0.05) compared with control. The slope of the positive relationship between CBFV and cerebral perfusion pressure (CPP = MAP - JVP) was steeper with isoflurane (P < 0.05) compared with control, as was the slope of the negative relationship between CPP and COE (P < 0.05). We conclude that burst-suppression doses of isoflurane decrease CBFV and impair autoregulation of cerebral blood flow during mildly hypothermic CPB. Furthermore, during isoflurane administration, blood flow was in excess relative to oxygen demand, indicating a loss of metabolic autoregulation of flow. IMPLICATIONS: The effects of isoflurane on cerebral blood flow velocity (CBFV) and oxygen extraction (COE) as a function of perfusion pressure were studied. When added to fentanyl anesthesia, isoflurane induced a 27% and 13% decrease in CBFV and COE, respectively. CBFV became more pressure-dependent with isoflurane indicating an impaired autoregulation.

Net pressure gradients in aortic prosthetic valves can be estimated by Doppler.

BACKGROUND: In aortic prosthetic valves, both the Doppler-estimated gradients and orifice areas are misleading in the assessment of hemodynamic performance. The parameter of major interest is the net pressure gradient after pressure recovery (PR). We, therefore, investigated, in vitro, our ability to predict the net pressure gradient and applied the formulas in a representative patient population with 2 different valve designs. METHODS: We studied the St Jude Medical (SJM) standard valve (size 19-27) and SJM Biocor (size 21-27) in an in vitro steady-flow model with simultaneous Doppler-estimated pressure and catheter pressure measurements. Using echocardiography, we also studied patients who received the SJM (n = 66) and SJM Biocor (n = 45). RESULTS: In the SJM, we observed PR both within the prosthesis and aorta, whereas in the SJM Biocor, PR was only present in the aorta. We estimated the PR within the valve and within the aorta separately from echocardiographic in vitro data, combining a regression equation (valve) with an equation on the basis of fluid mechanics theory (aorta). The difference between estimated and catheter-obtained net gradients (mean +/- SD) was 0.6 +/- 1.6 mm Hg in the SJM and -0.2 +/- 1.9 mm Hg in the SJM Biocor. When these equations were applied in vivo, we found that PR had an overall value of 57 +/- 7% of the peak Doppler gradient in the SJM and 33 +/- 9% in the SJM Biocor. CONCLUSIONS: The in vitro results indicate that it is possible to predict the net pressure gradient by Doppler in bileaflet and stented biologic valves. Our data indicate that important PR is also present in stented biologic valves.