Leidulf Segadal

Rewarming from accidental hypothermia by extracorporeal circulation. A retrospective study

OBJECTIVE Twenty-six patients with accidental hypothermia combined with circulatory arrest or severe circulatory failure were rewarmed to normothermia by use of extracorporeal circulation (ECC). The aim of the present study was to evaluate our results. PATIENTS AND METHODS The treatment of six female and 20 male patients (median age: 26.7 years; range 1.9--76.3 years) rewarmed in the period 1987--2000 was evaluated retrospectively. Hypothermia was related to immersion/submersion in cold water (n=17), avalanche (n=1) or prolonged exposure to cold surroundings (n=8). Prior to admission, the trachea was intubated and cardiopulmonary resuscitation (CPR) initiated in all patients with cardiorespiratory arrest (n=22), whereas in those with respiration/circulation (n=4) only oxygen therapy via a face mask was given. RESULTS Nineteen of the 26 patients were weaned off ECC whereas seven died because of refractory respiratory and/or cardiac failure. Eight of the 19 successfully weaned patients were discharged from hospital after a median of 10 days. One patient died 3 days after circulatory arrest (complete atrioventricular block) resulting in severe cerebral injury. The remaining ten patients died following 1--2 days due to severe hypoxic brain injury (n=5), cerebral bleeding (n=1) or irreversible cardiopulmonary insufficiency (n=4). Based on the reports from the site of accident, two groups of patients were identified: the asphyxia group (n=15) (submersions (n=14); avalanche accident (n=1)) and the non-asphyxia group (n=11) (patients immersed or exposed to cold environment). Seven intact survivors discharged from hospital belonged to the non-asphyxia group whereas one with a severe neurological deficit was identified within the asphyxia group. CONCLUSION Patients with non-asphyxiated deep accidental hypothermia have a reasonable prognosis and should be rewarmed before further therapeutic decisions are made. In contrast, drowned patients with secondary hypothermia have a very poor prognosis. The treatment protocol under such conditions should be the subject for further discussion.

Myocardial deformation in aortic valve stenosis: relation to left ventricular geometry.

Objective To assess left ventricular (LV) strain and displacement and their relations to LV geometry in patients with aortic stenosis (AS). Design Cross-sectional echocardiographic study in patients with AS. Peak circumferential, radial and longitudinal strain, and radial, longitudinal and transverse displacement were measured by 2D speckle tracking. Severity of AS was assessed from energy loss index (ELI). LV hypertrophy was present if LV mass/height2.7 ≥46.7/49.2 g/m2.7 in women/men and concentric LV geometry if relative wall thickness ≥0.43. LV geometry was assessed from LV mass/height2.7 and relative wall thickness in combination. Setting Department of Heart Disease, Haukeland University Hospital, Bergen, Norway. Patients 70 patients with AS (mean age 73±10 years, 54% women). Interventions None. Main outcome measures Association of regional and average LV myocardial strain and displacement with LV geometric pattern and degree of AS. Results Average longitudinal strain was lower in the hypertrophy groups and correlated with higher LV mass index and relative wall thickness, lower stress-corrected mid-wall shortening and smaller ELI (all p<0.05). Average strain and displacement in other directions did not differ between geometric groups. In multivariate regression analysis, lower average longitudinal strain was associated with higher relative wall thickness (β=0.15), lower ejection fraction (β=−0.16), systolic blood pressure (β=−0.16) and energy loss index (β=−0.20) (all p<0.05) (R2=0.72). When relative wall thickness was replaced with LV mass, lower longitudinal strain was also associated with higher LV mass (β=0.21, p<0.05) (R2=0.73). Conclusions In patients with AS, lower average longitudinal strain is related to higher LV mass, concentric geometry and more severe AS.

Patient-reported outcomes as predictors of 10-year survival in women after acute myocardial infarction

BackgroundPatient-reported outcomes are increasingly seen as complementary to biomedical measures. However, their prognostic importance has yet to be established, particularly in female long-term myocardial infarction (MI) survivors. We aimed to determine whether 10-year survival in older women after MI relates to patient-reported outcomes, and to compare their survival with that of the general female population.MethodsWe included all women aged 60-80 years suffering MI during 1992-1997, and treated at one university hospital in Norway. In 1998, 145 (60% of those alive) completed a questionnaire package including socio-demographics, the Sense of Coherence Scale (SOC-29), the World Health Organization Quality of Life Instrument Abbreviated (WHOQOL-BREF) and an item on positive effects of illness. Clinical information was based on self-reports and hospital medical records data. We obtained complete data on vital status.ResultsThe all-cause mortality rate during the 1998-2008 follow-up of all patients was 41%. In adjusted analysis, the conventional predictors s-creatinine (HR 1.26 per 10% increase) and left ventricular ejection fraction below 30% (HR 27.38), as well as patient-reported outcomes like living alone (HR 6.24), dissatisfaction with self-rated health (HR 6.26), impaired psychological quality of life (HR 0.60 per 10 points difference), and experience of positive effects of illness (HR 6.30), predicted all-cause death. Major adverse cardiac and cerebral events were also significantly associated with both conventional predictors and patient-reported outcomes. Sense of coherence did not predict adverse events. Finally, 10-year survival was not significantly different from that of the general female population.ConclusionPatient-reported outcomes have long-term prognostic importance, and should be taken into account when planning aftercare of low-risk older female MI patients.

Evaluation of the microsphere-method for determination of cardiac output

Cardiac output was determined by means of radioactive microspheres, 15 +/- 5 microns in diameter. Blood flow in the ascending aorta was measured by an electromagnetic flowmeter. In eight cats thirty-eight simultaneous measurements were made of cardiac output and aortic flow. The observations correlated well (r = 0.89), with a mean difference of 5.2%, probably corresponding to coronary blood flow. Continuous flow recordings showed no alterations in aortic flow during the injections of microspheres; arterial blood pressure and heart rate remained unchanged even after six injections, each consisting of about 2 x 10(5) spheres per kg body weight. Tests for shunting of microspheres were performed and revealed shunt fractions in the systemic circulation of about 8%, with no significant shunting through the lungs. The microsphere method for determining cardiac output is thought to be an accurate method, suitable for small and medium sized animals.

An anaesthetic protocol in the young domestic pig allowing neuromuscular blockade for studies of cardiac function following cardioplegic arrest and cardiopulmonary bypass

Background:  Neuromuscular blockade should, for ethical reasons, not be allowed in animal experiments unless the use is strongly motivated. Beforehand, the anaesthetic protocol must be documented without muscle relaxation in the species studied. Documentation is difficult to obtain from the scientific literature. When focusing on cardiac function over time, in particular, the ideal anaesthetic protocol should cause no or minor alterations in cardiac variables.

Multidose Cold Oxygenated Blood Is Superior to a Single Dose of Bretschneider HTK-Cardioplegia in the Pig

BACKGROUND A single-dose strategy for cardioplegia is desired in minimal invasive approaches to valve surgery and aortic arch repairs. We hypothesized that a single infusion of Bretschneider HTK solution offers myocardial protection comparable to repeated cold oxygenated blood. METHODS Sixteen pigs on bypass with 60 minutes of aortic cross-clamping were randomized to a single dose of Custodiol (HTK group) or repeated oxygenated blood cardioplegia (CBC group). Left ventricular function and perfusion were evaluated by conductance catheter, echocardiography, and microspheres. Myocardial injury was assessed with serum troponin-T. RESULTS Baseline values showed no group differences. One hour after declamping cardiac index was reduced in the HTK group, 3.5 +/- 0.2 L x min(-1) x m(-2) (mean +/- standard error of the mean) compared with 4.7 +/- 0.4 L x min(-1) x m(-2) in the CBC group (p < 0.0005), decreasing to 4.0 +/- 0.2 and 3.9 +/- 0.2 L x min(-1) x m(-2) after 2 and 3 hours, respectively (p < 0.005 versus 1 hour). In the HTK group cardiac index remained low and unchanged. In the CBC group preload recruitable stroke work was 72.6 +/- 1.2 mm Hg 1 hour after declamping, decreasing to 65.2 +/- 2.5 and 60.3 +/- 3.9 mm Hg after 2 and 3 hours, respectively (p < 0.05 versus 1 hour). In the HTK group corresponding values after 1, 2, and 3 hours were low at 47.2 +/- 4.4, 48.4 +/- 4.2, and 50.7 +/- 4.3 mm Hg, respectively (p < 0.025 versus CBC for all). Subendocardial radial peak systolic strain averaged 80.5% +/- 4.8% after declamping in the CBC group versus 53.4% +/- 5.5% in the HTK group (p = 0.002). Serum troponin-T release was lower in the CBC group. CONCLUSIONS Repeated oxygenated blood cardioplegia provides better myocardial protection and preservation of left ventricular function than a single dose of HTK during the early hours after declamping.

Instantaneous cross-sectional flow velocity profiles: a comparative study of two ultrasound Doppler methods applied to an in vitro pulsatile flow model.

Two methods based on different techniques for construction of cross-sectional flow velocity profiles from Doppler ultrasound signals were compared: an intraluminal method using pulsed-wave Doppler echocardiography and an extraluminal method using two-dimensional (color) Doppler ultrasound. The methods were applied to an in vitro pulsatile flow model. With the intraluminal method, pulsed Doppler recordings obtained throughout several flow pulses at different positions across a tube were digitized, and cross-sectional flow velocity profiles were obtained by matching the onset of flow velocity at the various positions. With the extraluminal method, cross-sectional flow velocity profiles were obtained by time interpolation between the digital flow velocity data obtained from several flow velocity maps. The first flow velocity map was recorded at onset of flow and the following maps were incrementally delayed with 20 msec from one flow pulse to the next. The time lag caused by the time needed to update each of the flow velocity maps was compensated for by time interpolation between the sequentially recorded flow velocity maps. The cross-sectional flow velocity profiles obtained with the two methods were compared at identical positions within the tube model at equal flow settings and throughout the pulsatile flow periods. At three different flow settings with peak flow velocity of 0.3, 0.5, and 0.7 m/sec, the difference (mean +/- SD) between the obtained velocities were 0.01 +/- 0.04, -0.01 +/- 0.05, and -0.03 +/- 0.07 m/sec, respectively. The findings suggest that cross-sectional flow velocity profiles from pulsatile flow velocity recordings can be obtained equally well with both methods.

Continuous measurement of aortic blood velocity, after cardiac surgery, by means of an extractable doppler ultrasound probe

A new method has been developed for the continuous measurement of aortic blood velocity in patients following cardiac surgery. Using an extractable Doppler ultrasound probe placed on the ascending aorta, the changes in aortic velocity were recorded up to 24 h postoperatively, in 14 patients undergoing coronary bypass surgery. Volume flow rate is calculated from the mean velocity, the diameter of the aorta and the angle between the ultrasound beam and the direction of the blood flow, by means of an analogue flow calculator. Estimation of aortic flow showed a correlation of r = 0.79 with cardiac output measured by a thermodilution technique. The main advantage of the system is that it allows continuous monitoring of cardiac output, as well as short and long-term trend analyses, during the early postoperative period.

Cardiac arrest due to massive pulmonary embolism following caesarean section. Successful resuscitation and pulmonary embolectomy

A woman developed pulmonary embolism with cardiac arrest after caesarean section. Cardiopulmonary resuscitation was performed for 45 min during which echocardiography showed right ventricular dilatation. After stabilization, but still in a critical condition, the patient was transferred by airambulance to a hospital with facilities for extracorporeal circulation. A massive embolus was removed. Some hours after extubation the patient developed respiratory insuffiency and hypovolaemia. Re‐intubation was followed by severe hypotension requiring external cardiac compression for about 15 min. An emergency explorative laparotomy revealed a ruptured liver with a subcapsular haematoma. A critical illness polyneuropathy made prolonged ventilatory support necessary. She recovered without cerebral sequelae.

Velocity distribution model for normal blood flow in the human ascending aorta

During the study of velocities in the human ascending aorta it became necessary to establish a method for two-dimensional velocity profiles from discrete velocity data obtained from different heartbeats and with different techniques. A descriptive geometrical model was therefore developed and expanded to 16 elements each containing 16 constants by a serial optimising technique using a least-squares method. Published data from two different studies on velocity distribution in the ascending aorta comprising six subjects with normal aortic valves were used. Threedimensional graphic displays of velocity profile at different time intervals of the heart cycle clearly show common features of distribution of velocity at a point 6 cm above the aortic valve. There was a pronounced skewness with clockwise rotation of the skwwness direction during systole, reversed flow directed towards the left coronary sinus of Valsalva in late systole and early diastole concomitant with secondary flow augmentation along the opposite wall of the aorta. Consistent plane-symmetric features during the heart cycle could not be demonstrated.