Untargeted toxicology in sudden cardiac arrest victims

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union’s Horizon 2020 research and innovation programme to J.T.-H under acronym ESCAPE-NET

Background

Sudden cardiac arrest (SCA) is a major public health challenge and is associated with poor outcomes. Many drugs are known to increase risk of arrythmias and ultimately sudden cardiac death. To our knowledge an untargeted toxicological analysis has not previously been performed in an initially resuscitated SCA cohort.

Purpose

We aimed to determine the qualitative and quantitative drug composition present in SCA patients by using forensic toxicological analytical chemistry of all illicit, non-prescription and prescribed drugs, and further investigate whether these drugs are in therapeutic levels or overdosed and to correlate the clinical findings with the toxicology results.

Methods

We performed a prospective single-tertiary-center study and included all SCA victims (aged 18-90 years) admitted to our cardiac intensive care unit, between February 2019 to November 2019 (Figure 1). Traumatic and overt overdose related SCA were not included in the study. Drugs used during resuscitation and administered prior to sample collection were identified in each patient and excluded.

Results

We prospectively identified 85 all-cause SCA patients with a median age of 60 years (IQR: 53-71) and male predominance (80%). The majority had a shockable rhythm as first rhythm (95%). The major cause of cardiac arrest was acute and chronic ischemia (56/77, 66%), followed by cardiomyopathy (9/77, 12%), idiopathic ventricular fibrillation (8/77, 10%), bradycardia (2/77, 2.6%), primary arrhythmia (1/77, 1.3%), other (1/77, 1.3%). The remaining 8 patients (9.4%) died prior to diagnosis.

A positive toxicology was identified in 67 patients (79%) with a total of 218 detected drugs. The most frequent drugs were mild analgesics (32/85, 38%), beta-blockers (21/85, 25%) and ACE-inhibitors/ARB (20/85, 24%). A total of 9 (11%) patients had one or more potentially abusable drugs detected, with the most common being opioid agonists in 5 patients (Figure 2). Importantly, all drugs were found at sub-therapeutic or therapeutic concentrations. None had overdose concentrations. Moreover, polypharmacy was common and a median of 2 drugs (IQR: 1-4) were detected (excluding caffeine that was detected in 83 patients).

Conclusion

We found that the majority had drugs detected, and polypharmacy is displayed in a considerable proportion. Potentially abusive drugs were encountered in 11%. However, we did not identify any occult overdose related cardiac arrests among all resuscitated SCA patients. In our setting, toxicological screening in cardiac arrest patients who is not obviously overdosed is excessive.

Higher vs lower doses of dexamethasone in patients with COVID-19 and severe hypoxia (COVID STEROID 2) trial: Protocol and statistical analysis plan

Background

The coronavirus disease 2019 (COVID‐19) pandemic has resulted in millions of deaths and overburdened healthcare systems worldwide. Systemic low‐dose corticosteroids have proven clinical benefit in patients with severe COVID‐19. Higher doses of corticosteroids are used in other inflammatory lung diseases and may offer additional clinical benefits in COVID‐19. At present, the balance between benefits and harms of higher vs. lower doses of corticosteroids for patients with COVID‐19 is unclear.

Methods

The COVID STEROID 2 trial is an investigator‐initiated, international, parallel‐grouped, blinded, centrally randomised and stratified clinical trial assessing higher (12 mg) vs. lower (6 mg) doses of dexamethasone for adults with COVID‐19 and severe hypoxia. We plan to enrol 1,000 patients in Denmark, Sweden, Switzerland and India. The primary outcome is days alive without life support (invasive mechanical ventilation, circulatory support or renal replacement therapy) at day 28. Secondary outcomes include serious adverse reactions at day 28; all‐cause mortality at day 28, 90 and 180; days alive without life support at day 90; days alive and out of hospital at day 90; and health‐related quality of life at day 180. The primary outcome will be analysed using the Kryger Jensen and Lange test adjusted for stratification variables and reported as adjusted mean differences and median differences. The full statistical analysis plan is outlined in this protocol.

Discussion

The COVID STEROID 2 trial will provide evidence on the optimal dosing of systemic corticosteroids for COVID‐19 patients with severe hypoxia with important implications for patients, their relatives and society.

P3347Pre-hospital time and 30-day mortality in patients with presumed heart conditions or dyspnea: a registry-based cohort study of patients requiring a highest priority emergency medical response

Introduction

Centralization of emergency care is expected to increase average pre-hospital time for patients, leading to concerns about possible adverse outcomes for patients. Prior studies have found increased mortality for patients with prolonged transport following acute myocardial infarction.

Purpose

Examine the association between total pre-hospital time (from dispatch to hospital arrival) and mortality for patients, depending on the condition presumed by the emergency dispatcher (presumed heart condition, dyspnea or non-specific medial conditions).

Methods

Pre-hospital registry data from a Danish region from 2006–2012 was used. This contained information on ambulance dispatch priority, ambulance times, and patient condition, as well if procedures consistent with cardiac arrest (CPR or shock) were performed. We included patients with both highest priority dispatch and transport to the hospital. Linkage to nationwide registries of hospital admissions, comorbidities and mortality was performed. Logistic regression was used for analysis.

Results

95% of total pre-hospital times were below 84 minutes. 30-day mortality was highest among patients with dyspnea (36.6%). Compared to pre-hospital times of 0–30 min, odds ratios of 30-day mortality for times >60 min were: for presumed heart conditions 0.54 [95% CI 0.38–0.77] (p<0.001), for dyspnea 0.98 [95% CI 0.65–1.47] and for other medical conditions 1.14 [95% CI 0.98–1.32]

Patient characteristics and outcomes according to the presumed aetiology of the priority 1 emergency dispatch Presumed heart condition Dyspnea Other medical conditions N 1836 1101 11538 Age, median {IQR} 66.4 {55.3, 76.8} 70.5 {56.8, 80.8} 61.5 {40.3, 75.8} Male, n (%) 1194 (65.0) 585 (53.1) 6172 (53.5) 10-year Charlson comorbidity index score ≥3, n (%) 744 (40.5) 613 (55.7) 4311 (37.6) Response time, median {IQR} 9 {5, 13} 9 {5, 13} 8 {5, 13} Total pre-hospital time, median {IQR} 49{37,61} 45{34, 58} 46{34,58} Cardiac arrest procedures during transport, n (%) 266 (14.5) 133 (12.1) 844 (7.3) Cardiovascular diagnosis (DI00-DI99), n (%) 962 (52.4) 282 (25.6) 3285 (28.5) Respiratory diagnosis (DJ00-DJ99), n (%) 82 (4.5) 430 (39.1) 1036 (9.0) 1-day mortality, n (%) 289 (15.7) 225 (20.4) 1311 (11.4) 30-day mortality, n (%) 402 (21.9) 403 (36.6) 2264 (19.6)

Logistic regression, 30-day mortality

Conclusion

No overall association between total pre-hospital time and mortality, however for presumed heart conditions longer times may improve survival.

Acknowledgement/Funding

Program for clinical research infrastructure (PROCRIN) established by the Lundbeck and Novo Nordisk foundations & The Danish Heart Foundation

Intensive care doctors' preferences for arterial oxygen tension levels in mechanically ventilated patients

BACKGROUND

Oxygen is liberally administered in intensive care units (ICUs). Nevertheless, ICU doctors' preferences for supplementing oxygen are inadequately described. The aim was to identify ICU doctors' preferences for arterial oxygenation levels in mechanically ventilated adult ICU patients.

METHODS

In April to August 2016, an online multiple-choice 17-part-questionnaire was distributed to 1080 ICU doctors in seven Northern European countries. Repeated reminder e-mails were sent. The study ended in October 2016.

RESULTS

The response rate was 63%. When evaluating oxygenation 52% of respondents rated arterial oxygen tension (PaO₂ ) the most important parameter; 24% a combination of PaO₂ and arterial oxygen saturation (SaO₂ ); and 23% preferred SaO₂ . Increasing, decreasing or not changing a default fraction of inspired oxygen of 0.50 showed preferences for a PaO₂ around 8 kPa in patients with chronic obstructive pulmonary disease, a PaO₂ around 10 kPa in patients with healthy lungs, acute respiratory distress syndrome or sepsis, and a PaO₂ around 12 kPa in patients with cardiac or cerebral ischaemia. Eighty per cent would accept a PaO₂ of 8 kPa or lower and 77% would accept a PaO₂ of 12 kPa or higher in a clinical trial of oxygenation targets.

CONCLUSION

Intensive care unit doctors preferred PaO₂ to SaO₂ in monitoring oxygen treatment when peripheral oxygen saturation was not included in the question. The identification of PaO₂ as the preferred target and the thorough clarification of preferences are important when ascertaining optimal oxygenation targets. In particular when designing future clinical trials of higher vs lower oxygenation targets in ICU patients.

Oxygen supplementation for critically ill patients-A protocol for a systematic review

BACKGROUND

In critically ill patients, hypoxaemia is a common clinical manifestation of inadequate gas exchange in the lungs. Supplemental oxygen is therefore given to all critically ill patients. This can result in hyperoxaemia, and some observational studies have identified harms with hyperoxia. The objective of this systematic review is to critically assess the evidence of randomised clinical trials on the effects of higher versus lower inspiratory oxygen fractions or targets of arterial oxygenation in critically ill adult patients.

METHODS

We will search for randomised clinical trials in major international databases. Two authors will independently screen and select references for inclusion using Covidence, extract data and assess the methodological quality of the included randomised clinical trials using the Cochrane risk of bias tool. Any disagreement will be resolved by consensus. We will analyse the extracted data using Review Manager and Trial Sequential Analysis. To assess the quality of the evidence, we will create a 'Summary of Findings' table containing our primary and secondary outcomes using the GRADE assessment.

DISCUSSION

Supplemental oxygen administration is widely recommended in international guidelines despite lack of robust evidence of its effectiveness. To our knowledge, no systematic review of randomised clinical trials has investigated the effects of oxygen supplementation in critically ill patients. This systematic review will provide reliable evidence to better inform future trialists and decision-makers on clinical practice on supplemental oxygen administration in critically ill patients.

Forced fluid removal in intensive care patients with acute kidney injury: The randomised FFAKI feasibility trial

BACKGROUND

Accumulation of fluids is frequent in intensive care unit (ICU) patients with acute kidney injury and may be associated with increased mortality and decreased renal recovery. We present the results of a pilot trial assessing the feasibility of forced fluid removal in ICU patients with acute kidney injury and fluid accumulation of more than 10% ideal bodyweight.

METHODS

The FFAKI-trial was a pilot trial of forced fluid removal vs standard care in adult ICU patients with moderate to high risk acute kidney injury and 10% fluid accumulation. Fluid removal was done with furosemide and/or continuous renal replacement therapy aiming at net negative fluid balance > 1 mL/kg ideal body weight/hour until cumulative fluid balance calculated from ICU admission reached less than 1000 mL.

RESULTS

After 20 months, we stopped the trial prematurely due to a low inclusion rate with 23 (2%) included patients out of the 1144 screened. Despite the reduced sample size, we observed a marked reduction in cumulative fluid balance 5 days after randomisation (mean difference -5814 mL, 95% CI -2063 to -9565, P = .003) with forced fluid removal compared to standard care. While the trial was underpowered for clinical endpoints, no point estimates suggested harm from forced fluid removal.

CONCLUSIONS

Forced fluid removal aiming at 1 mL/kg ideal body weight/hour may be an effective treatment of fluid accumulation in ICU patients with acute kidney injury. A definitive trial using our inclusion criteria seems less feasible based on our inclusion rate of only 2%.

Effects of fluid restriction on measures of circulatory efficacy in adults with septic shock

BACKGROUND

The haemodynamic consequences of fluid resuscitation in septic shock have not been fully elucidated. Therefore, we assessed circulatory effects in the first 24 h of restriction of resuscitation fluid as compared to standard care in intensive care unit (ICU) patients with septic shock.

METHODS

This was a post-hoc analysis of the multicentre CLASSIC randomised trial in which patients with septic shock, who had received the initial fluid resuscitation, were randomised to a protocol restricting resuscitation fluid or a standard care protocol in nine ICUs. The highest plasma lactate, highest dose of noradrenaline, and the urinary output were recorded in five time frames in the first 24 h after randomisation. We used multiple linear mixed effects models to compare the two groups.

RESULTS

We included all 151 randomised patients; the cumulated fluid resuscitation volume in the first 24 h after randomisation was median 500 ml (Interquartile range (IQR) 0-1500) and 1250 ml (500-2500) in the fluid restriction group and standard care group, respectively. The estimated differences in the fluid restriction group vs. the standard care group were 0.1 mM (95% confidence interval -0.7 to 0.9; P = 0.86) for lactate, 0.01 μg/kg/min (-0.02 to 0.05; P = 0.48) for dose of noradrenaline, and -0.1 ml/kg/h (-0.3 to 0.2; P = 0.70) for urinary output during the first 24 h after randomisation.

CONCLUSIONS

We observed no indications of worsening of measures of circulatory efficacy in the first 24 h of restriction of resuscitation fluid as compared with standard care in adults with septic shock who had received initial resuscitation.

Variability in targeted arterial oxygenation levels in patients with severe sepsis or septic shock

BACKGROUND

Supplemental oxygen therapy is used for intensive care (ICU) patients with severe sepsis, but with no general guidelines and few safety data. The aim of this observational study was to describe the variability in oxygen administration as well as the association between partial pressure of arterial oxygen (PaO2 ) and mortality.

METHODS

We extracted data from two Scandinavian clinical trials of ICU patients with severe sepsis or septic shock. We calculated average PaO2 and fraction of inspired oxygen (FiO2 ) from trial inclusion and the following 5 days, and assessed the association between PaO2 and 90-day mortality.

RESULTS

The median PaO2 was 9.8 kPa [5-95% range 6.4-19.9] and FiO2 was 0.51 [5-95% range 0.27-1.00], respectively. Eight hundred and five of 1,770 patients (45%) died. The relative risk of mortality was 1.43 [95% CI: 1.19-1.65] in patients with average PaO2 < 8 kPa and 1.29 [95% CI: 0.84-1.68] in patients with average PaO2 ≥ 16 kPa, as compared to patients with average PaO2 10-12 kPa. The relative risk of mortality was 1.38 [95% CI: 1.17-1.58] in patients with an average FiO2 0.60-0.80 and 2.10 [95% CI: 1.88-2.23] in patients with an average FiO2  ≥ 0.80 as compared to patients with an average FiO2  ≤ 0.40.

CONCLUSION

Administration of oxygen in patients with severe sepsis resulted in a wide range of PaO2 . Significantly higher mortality was observed in patients with an average PaO2 < 8 kPa and FiO2 ≥ 0.60. The results do not imply causation and the associations between average PaO2 and adverse outcomes have to be assessed further.

Should blood flow during cardiopulmonary bypass be individualized more than to body surface area?

Blood flow during cardiopulmonary bypass (CPB) is calculated on body surface area (BSA). Increasing comorbidity, age and weight of today’s cardiac patients question this calculation as it may not reflect individual metabolic requirement. The hypothesis was that a measured cardiac index (CI) prior to normothermic CPB is a better estimate. A cross-over study, with random allocation to CPB blood flow for 20 minutes based on either a calculation (2.4 L/min/m2) or on CI, with a switch to the opposite flow for another 20 minutes, was performed. Twenty-two elective cardiac surgery patients with normal ventricular function were included. Effect parameters were cerebral oxygenation, mixed venous saturation and arterial lactate. CI varied from 1.9 to 3.1 L/min/m2 (median 2.4 L/min/m2). No differences in effect parameters were seen. In conclusion, a CPB blood flow based on an individual estimate did not improve cerebral and systemic oxygenation compared to a blood flow based on BSA.

Oxygenation and release of inflammatory mediators after off-pump compared with after on-pump coronary artery bypass surgery

BACKGROUND

In a previous study, we showed that oxygenation was impaired for up to 5 day after conventional coronary artery bypass grafting (CABG). As cardiopulmonary bypass (CPB) may have a detrimental effect on pulmonary function, we hypothesized that coronary revascularization grafting without the use of CPB (OPCAB) would affect post-operative oxygenation and release of inflammatory mediators less compared with CABG.

METHODS

Low-risk patients scheduled for elective coronary revascularization were randomly assigned to one of two groups (CABG, n = 17 or OPCAB, n = 18). Two parameters of oxygenation, shunt (%) and ventilation-perfusions mismatch, described as DeltaPO(2) (kPa), were estimated for up to 5 days post-operatively. Systemic release of interleukin (IL)-6, -8 and -10, C-reactive protein (CRP) and neutrophils were measured in peripheral blood samples for up to 3 days post-operatively. The lungs participation in the cytokine response was evaluated from mixed venous blood samples taken within the first 16 h post-operatively.

RESULTS

OPCAB was followed by a higher shunt (P = 0.047), with no difference (P = 0.47) in the deterioration of DeltaPO(2) between the groups. OPCAB was followed by an attenuated systemic release of IL-8 (P = 0.041) and IL-10 (P = 0.006), while the release of IL-6 (P = 0.94), CRP (P = 0.121) and neutrophils (P = 0.078) did not differ between the groups. Indications of an uptake of cytokines in the lungs were found after OPCAB.

CONCLUSIONS

When comparing OPCAB with CABG, oxygenation was more affected and only part of the systemic inflammatory response was attenuated.

Oxygenation within the first 120 h following coronary artery bypass grafting. Influence of systemic hypothermia (32 degrees C) or normothermia (36 degrees C) during the cardiopulmonary bypass: a randomized clinical trial

BACKGROUND

Lung function is often impaired after cardiac surgery performed under cardiopulmonary bypass (CPB). Normothermic CPB has become more common, but it remains unknown whether it reduces post-operative lung function compared with hypothermic CPB. The aim of this study was to investigate oxygenation within the first 120 h after systemic hypothermia and normothermia under CPB.

METHODS

Thirty patients undergoing coronary artery bypass grafting (CABG) were randomized to either hypothermic (32 degrees C) or normothermic (36 degrees C) CPB. Oxygenation was studied by a simple method for the estimation of intrapulmonary shunt and ventilation-perfusion (V/Q) mismatch pre-operatively and 4, 48 and 120 h post-operatively by changing Fio2 in four to six steps. V/Q mismatch was described with DeltaPo2 (normal values, 0-2.38 kPa).

RESULTS

Shunt and V/Q mismatch (DeltaPo2) increased post-operatively in both groups (P<0.01), with no differences between the groups, and with the nadir values 48 h after surgery, i.e. shunt of 15% (5.8-25%) and DeltaPo2 of 3.0 kPa (0.8-14 kPa) [values given as median (range)].

CONCLUSIONS

Impaired oxygenation is prevalent and prolonged following CABG, with equal intensity after hypothermic and normothermic CPB.

Myocardial structure as a determinant of pre- and postoperative ventricular function and long-term prognosis after valve replacement for aortic stenosis

BACKGROUND

Long-term results after aortic value replacement for aortic stenosis can be correlated to a cardiac-related pre-operative risk profile. This predictability indicates that there is a common basis in subtle or overt structural abnormalities of left ventricular myocardium.

METHODS AND RESULTS

Forty-nine patients aged 24-82 (mean 61) years, with aortic stenosis had a full wall thickness transmural biopsy of the left ventricular antero-lateral free wall during aortic valve replacement. Echocardiography and radionuclide ventriculography were performed prior to, and 18 months (n = 41) after, the operation. Postoperative follow-up to a maximum of 7.7 years was 100% complete. Pre-operatively, all patients had an increase in both the left ventricular mass index (202 +/- 67 g.m-2) and the muscle cell diameter (41 +/- 8 microns); other morphological data included a muscle cell nucleus volume of 752 +/- 192 microns3, a muscle cell mass index of 163 +/- 54.m-2, and a fibrous tissue mass index of 39 +/- 16 g.m-2. Patients with a pre-operative episode of clinical left ventricular failure (n = 19) had significantly greater morphological variables than those without. Pre-operative ejection fraction and other measures of systolic function correlated inversely with the morphological data, except for the fibrous tissue mass index; diastolic function indices correlated inversely with all the morphological variables. At the 18-month re-study, the same general picture was noted, but with an underlying strengthening, especially of the muscle cell mass index. Overall, the mass index dropped to 152 +/- 51 g.m-2 (P < 0.0001), but in 17% of the patients it became normal; the mass index at 18 months was directly correlated to morphological variables. A high muscle cell nucleus volume was identified as an independent predictor of early and late mortality.

CONCLUSIONS

Abnormalities of the hypertrophied left ventricular muscle cell and the degree of muscle hypertrophy are, to some degree, underlying determinants of pre-operative symptomatology, pre- and postoperative ventricular function, and early and late mortality after valve replacement for aortic stenosis. Incomplete hypertrophy impaired results, was related to pre-operative myocardial structural abnormalities.

[Mortality and worsening of prognosis for patients with aortic stenosis while on the waiting list]

In a prospective study, 99 consecutive patients with an operative indication due to severe aortic stenosis (AS) were put on a surgical waiting list. The waiting time to aortic valve replacement (AVR) averaged 6.3 months (0.5-19 months). There were 58 men and 41 women with a mean age of 61 years (21-82 years). The patients were divided into three groups: group 1 (N = 81) with an uneventful stay on the waiting list; group 2 (N = 11) with significant worsening of a prognostic index; and group 3 (N = 7) with patients who died during the waiting time. The waiting list death rate was 13.5%/patient-year compared with a post-AVR death rate of 4.9% patient-year (p < 0.05) with a mean post-AVR follow-up of 5.7 years. According to a prognostic index (Cox regression model) at inclusion, group 2 patients had a predicted 7-year post-AVR survival probability of 72%, but only of 61% according to their prognostic index immediately preoperatively; their observed 7-year post-AVR survival was 60%. Logistic regression analysis identified high age, short duration of symptoms, signs of severe hypertrophy and strain in the ECG, female gender, and deranged left ventricular diastolic function (related to severely increased left ventricular muscle mass) as independent predictors of prognostic worsening and death while on the waiting list. The predictive models did not allow sufficiently accurate identification of the patients at risk during the waiting period. The consequences of a surgical waiting period averaging 6 months are serious for AS patients. The death rate is high and a subgroup worsens its prognostic profile with a significantly reduced post-AVR long-term survival as the result.

Left ventricular systolic and diastolic function in aortic stenosis. Prognostic value after valve replacement and underlying mechanisms

AIMS

The aims of the study were to examine the prognostic value of pre-operative left ventricular systolic and diastolic function on early, and late mortality after valve replacement for aortic stenosis, and to identify possible underlying mechanisms.

METHODS AND RESULTS

Ninety-one prospectively recruited consecutive patients with a mean age of 61 years underwent valve replacement for aortic stenosis with concomitant coronary artery bypass grafting in 32 and a minimum postoperative observation period of 5.4 years. There were six early (< or = 30 days postoperatively) and 19 late deaths, and 18 deaths from specific causes (cardiac and prosthetic valve related). Early mortality occurred exclusively among patients with a combined subnormal left ventricular systolic function (subnormal ejection fraction or peak ejection rate, or supranormal time-to-peak ejection--duration of systole ratio) and a subnormal fast filling fraction. In Cox regression models on crude mortality and specific deaths, a subnormal ejection fraction and a fast filling fraction of < or = 45% were the only independent risk factors. Patients with none of these risk factors had normal sex- and age-specific survival, those with any one factor had an early, and those with both factors a massive early and a late excess mortality, with 5-year crude survival of 92%, 77%, and 50%, respectively (P < 0.0001). Systolic wall stress was without prognostic value. Further analyses indicated that impairment of left ventricular function occurred with increasing muscle mass over two phases: (1) diastolic dysfunction characterized by a pattern of severe relative concentric hypertrophy; (2) the addition of systolic dysfunction characterized by a more dilated, less concentric chamber geometry. Coronary artery disease seemed to provoke the latter development sooner.

CONCLUSIONS

Impaired systolic and diastolic left ventricular function, irrespective of afterload, were decisive independent pre-operative risk factors for early as well as late mortality after aortic valve replacement for aortic stenosis. The adverse influence of concentric hypertrophy was the main underlying mechanism. Operative intervention, before impairment of diastolic and systolic function, should be advocated.

Impact of size mismatch and left ventricular function on performance of the St. Jude disc valve after aortic valve replacement

BACKGROUND

The hemodynamic function of the St. Jude valve may change relative to changes in left ventricular function after aortic valve replacement for aortic stenosis. From theoretical reasons one may hypothesize that prosthetic valve hemodynamic function is related to left ventricular failure and mismatch between valve size and patient/ventricular chamber size.

METHODS

Forty patients aged 24 to 82 years who survived aortic valve replacement for aortic stenosis with a standard St. Jude disc valve (mean size, 23.5 mm; range, 19 to 29 mm) were followed up prospectively with Doppler echocardiography and radionuclide left ventriculography preoperatively and 9 days, 3 months, and 18 months after the operation with assessment of intravascular hemolysis at 18 months. Follow-up to a maximum of 7.4 years (mean, 6.3 years) was 100% complete.

RESULTS

Left ventricular muscle mass index decreased from 198 +/- 62 g.m-2 preoperatively to 153 +/- 53 g.m-2 at 18 months (p < 0.001), paralleled by a significant increase in left ventricular ejection fraction, peak ejection rate, and peak filling rate; only 18% of the patients had normal left ventricular muscle mass index and only 32% normal ventricular function (normal left ventricular ejection fraction, peak ejection rate, peak filling rate, early filling fraction, and late filling fraction during atrial contraction) at 18 months. Prosthetic valve peak Doppler gradient dropped from 20 +/- 6 mm Hg at 9 days to 17 +/- 5 mm Hg at 18 months (p < 0.05). Reduction of left ventricular muscle mass index was unrelated to peak gradient and size of the valve. Peak gradient at 18 months rose with valve orifice diameter of 17 mm or less (by 6 mm Hg), orifice diameter/body surface area of 9 mm.m-2 or less (by 5 mm Hg), left ventricular enddiastolic dimension (by 23 mm Hg per 10 mm increase), and impaired ventricular function (by 3 mm Hg). All but 2 patients (5%) had intravascular hemolysis; none had anemia. Two patients with moderate paravalvular leak had the highest serum lactic dehydrogenase levels; 4 patients with trivial leak had higher serum lactic dehydrogenase levels than those without leak. Serum lactic dehydrogenase levels rose with moderate paravalvular leak, impaired ventricular function, and valve orifice diameter. Six patients with trivial or moderate paravalvular leak had a cumulative 7-year freedom from bleeding and thromboembolism of 44% +/- 22% compared with 87% +/- 5% for those without leak (p < 0.05).

CONCLUSIONS

The peak gradient of the St. Jude aortic valve dropped marginally over the first 18 postoperative months in association with incomplete left ventricular hypertrophy regression and marginal improvement of ventricular function. Mismatch between valve size and ventricular cavity size or patient size and impaired function of a dilated ventricle significantly compromised the performance of the St. Jude valve. Probably explained by platelet destruction or activation, paravalvular leak was related to bleeding and thromboembolic complications.

[Data and quality assurance tools from a new cardiac center in Denmark]

Open heart surgery was established at Aalborg Hospital in 1992. In the time period March to December 1992 cardiac anaesthesia was administered in 98 operations utilizing extracorporeal circulation and cardiopulmonary bypass. Mortality in coronary artery surgery was 1.6%. All patients were prospectively registered using a new dataform allowing registration of 228 patients related variables concerning preoperative status, course of anaesthesia and perfusion, surgery and postoperative intensive care. Quality assurance in cardiac surgery requires risk factor analysis, and registration of numerous data is a necessary tool. The software for our database system has been developed and programmed using the database programme dBASE IV from the Ashton/Tate Corporation.

[Surgical treatment of hydronephrosis. Late results after surgery using the Anderson-Hynes method]

Twenty-one patients with hydronephrosis mean age 37 years (11-72) were operated using Anderson-Hynes pyeloplasty, without routine use of a nephrostomy catheter. One patient developed urinary leakage postoperatively, which ceased after insertion of a ureteric catheter. Follow-up assessment was performed after a mean observation time of 85 months (44-142). Clinical examination, laboratory investigations, urography and renography were performed preoperatively and at follow-up. No signs of stones or stenosis in the pelvis were found. The patients operated upon before the age of 30 showed improved postoperative renal function. All patients had symptoms preoperatively, but only one had symptoms postoperatively. It can be concluded that the results of surgical intervention in hydronephrosis are excellent, especially in patients below 30 years.

Long-term follow-up of patients with hydronephrosis treated by Anderson-Hynes pyeloplasty

A series of 21 patients with hydronephrosis (mean age 37 years) underwent an Anderson-Hynes pyeloplasty; a nephrostomy catheter was not used routinely. One patient developed urinary leakage post-operatively but this ceased following insertion of a ureteric catheter. Assessment was carried out after a mean observation time of 85 months. Clinical examination, laboratory investigations, urography and renography were performed pre-operatively and at follow-up. There was no evidence of stones or stenosis in the pelvis. Patients operated upon before the age of 30 years showed improved renal function. All patients had symptoms pre-operatively but only one had symptoms post-operatively. It was concluded that the results of surgical intervention in hydronephrosis are excellent, especially in patients aged less than 30 years.

Intrapleural administration of 0.5% plain bupivacaine compared to 0.5% epinephrine: a hemodynamic and ventilatory study

The ventilatory and hemodynamic effects of 20 ml 0.5% intrapleural bupivacaine with and without 5 micrograms/ml epinephrine were studied. Ten patients scheduled for intrapleural block in the treatment of chronic visceral pain had a left-sided intrapleural catheter inserted. In a double-blind, crossover design they received 20 ml 0.5% bupivacaine with and without 5 micrograms/ml epinephrine. Forced vital capacity, vital capacity, and forced expiratory volume in one second were measured before and 30 minutes after the injection. Mean blood pressure, heart rate, and cardiac output were recorded before the injection and at five-minute intervals for 30 minutes. Vital capacity, forced vital capacity, and forced expiratory volume in one second were unchanged in both groups. There were no differences in any of the pulmonary function tests between the groups. When data from both groups are pooled, vital capacity shows a decrease of 7% (p less than 0.05). No changes in heart rate or mean blood pressure were seen in either group. Bupivacaine without epinephrine did not affect the cardiac output, whereas bupivacaine with epinephrine resulted in a rise in cardiac output of 15% at 15 and 20 minutes after the injection. We did not find any major effects of intrapleural injection of 20 ml 0.5% bupivacaine with and without 5 micrograms/ml epinephrine on ventilatory capacity or cardiovascular function in patients treated for chronic visceral pain.

Postspinal headache in young and elderly patients. Two randomised, double-blind studies that compare 20- and 25-gauge needles

In two randomised, double-blind studies of elderly patients with a mean age of 68.9 (range 21-88) years and young patients, mean age 29.4 (range 20-40) years, the effect of needle size on the incidence of postspinal headache was compared. The two needle groups, 20- and 25-gauge, were comparable in both studies with regard to number, sex, age and type of surgery. The incidence of postspinal headache in young patients was 27.6% when a 20-gauge needle was used and 12.6% with a 25-gauge needle. There was no significant difference in either the incidence of headache in the elderly patients (10.8% and 7.8%, respectively) or between the sexes. It is concluded that it does not matter if a 20- or a 25-gauge needle is used for spinal analgesia in elderly patients with regard to postspinal headache, but if spinal analgesia is indicated in young patients a fine needle is preferred.

Impaired pulmonary and cardiac function after maximal exercise

The cardiopulmonary response to maximal rowing exercise of short duration was studied in six healthy well-trained oarsmen. The lung diffusing capacity for carbon monoxide was significantly decreased below the pre-exercise value for 2.5 days post-exercise (P less than 0.05). Residual volume (RV) showed a significantly increased value at 30 min of recovery (P less than 0.01) with no change in total lung capacity. There was no significant change in transthoracic electrical impedance following exercise but a decrease may have been masked by the increased RV. The changes in the pulmonary parameters may reflect the occurrence of a transient interstitial lung oedema. Exercise-induced bronchoconstriction may be a part of the cardiopulmonary response as peak expiratory flow rate (PEFR) was significantly reduced at 30 min of recovery. The reason for the increase in pulmonary extravascular water volume may be a marked distension of the lung capillaries due to increased blood volume in the lungs and as a consequence increased vascular permeability. The changes may also be caused by impaired myocardial contractility indicated by a split impedance dZ/dt waveform, not previously described in healthy persons, which occurred in all six subjects immediately following exercise.

Decrease in pulmonary diffusion capacity after maximal exercise

Oppression of the chest, cough and orthopnea are well known to occur in some athletes after competitions, maybe reflecting an increase in lung water. In order to indicate if lung water increases after maximal exercise we measured pulmonary diffusion capacity before and 2.1 h after a short maximal arm exercise bout in 11 canoeists and showed a decrease of 6.7%. The result may be explained by a calculated 17% increase in alveolar interstitial volume.