Plasma hyperosmolality during cardiopulmonary bypass is a risk factor for postoperative acute kidney injury: Results from double blind randomised controlled trial

INTRODUCTION

The study objective was to investigate whether a Ringer's acetate based priming solution with addition of Mannitol and sodium concentrate increases the risk of cardiac surgery associated kidney injury (CSA-AKI).

METHODS

This is a double blind, prospective randomized controlled trial from a single tertiary teaching hospital in Sweden including patients aged ≥65 years (n = 195) admitted for routine cardiac surgery with cardiopulmonary bypass. Patients in the study group received Ringer's acetate 1000 mL + 400 mL Mannitol (60 g) + sodium chloride 40 mL (160 mmol) and heparin 2 mL (10 000 IU) 966 mOsmol (n = 98), while patients in the control group received Ringer's acetate 1400 mL + heparin 2 mL (10 000 IU), 388 mOsmol (n = 97) as pump prime. Acute kidney injury was analysed based on the Kidney Disease Improving Outcomes (KDIGO 1-3) definition.

RESULTS

The overall incidence of CSA-AKI (KDIGO stage 1) was 2.6% on day 1 in the ICU and 5.6% on day 3, postoperatively. The serum creatinine level did not show any postoperative intergroup differences, when compared to baseline preoperative values. Six patients in the Ringer and five patients in the Mannitol group developed CSA-AKI (KDIGO 1-3), all with glomerular filtration rates <60 mL/min/1.73 m2. These patients showed significantly higher plasma osmolality levels compared to preoperative values. Hyperosmolality together with patient age and the duration of the surgery were independent risk factors for postoperative acute kidney injury (KDIGO 1-3).

CONCLUSIONS

The use of a hyperosmolar prime solution did not increase the incidence of postoperative CSA-AKI in this study, while high plasma osmolality alone increased the associated risk by 30%. The data suggests further examination of plasma hyperosmolality as a relative risk factor of CSA-AKI.

Is a hyperosmolar pump prime for cardiopulmonary bypass a risk factor for postoperative delirium? A double blinded randomised controlled trial

Objective: Postoperative delirium (POD) is common after cardiac surgery. We have previously identified plasma sodium concentration and the volume of infused fluids during surgery as possible risk factors. Both are linked to the selection and composition of the pump prime used for cardiopulmonary bypass (CPB). Present study aims to examine whether hyperosmolality increases the risk for POD. Design: Patients ≥65 years (n = 195) scheduled for cardiac surgery were prospectively enrolled into this double blinded randomised clinical trial. Study group received a pump prime containing mannitol and ringer-acetate (966 mOsmol) (n = 98) vs. ringer-acetate (388 mOsmol) (n = 97) in the control group. Postoperative delirium was defined according to DSM-5 criteria based on a test-battery pre- and postoperatively (days 1-3). Plasma osmolality was measured on five occasions and coordinated with the POD assessments. The primary outcome was the POD incidence related to hyperosmolality as the secondary outcome. Results: The incidence of POD was 36% in the study group and 34% in the control group, without intergroup difference (p=.59). The plasma osmolality was significantly higher in the study group, both on days 1 and 3 and after CPB (p<.001). Post hoc analysis indicated that high osmolality levels increased the risk for delirium on day 1 by 9% (odds ratio (OR) 1.09, 95% CI 1.03-1.15) and by 10% on day 3 (OR 1.10, 95% CI 1.04-1.16). Conclusions: Use of a prime solution with high osmolality did not increase the incidence of POD. However, the influence of hyperosmolality as a risk factor for POD warrants further investigation.

Accuracy of Visually Estimated Blood Loss in Surgical Sponges by Members of the Surgical Team

It is important that operating room personnel monitor the correct amount of blood loss during surgery in order to properly replace lost volume. The aim of this study was to investigate the accuracy of operating room personnel in visually estimating blood loss in surgical sponges. We performed an observational study with comparative descriptive design at a university hospital including all members of the surgical team. In total, 163 observations were completed. The participants estimated the amount of blood in surgical sponges in 4 stations with varying amounts of blood and/or numbers of sponges. Data were analyzed using the Wilcoxon signed rank, Kruskal-Wallis, and Mann-Whit-ney tests. Both overestimations and underestimations occurred. Underestimations dominated and tended to increase with major amounts of blood. Operating room personnel miscalculated the amount of blood by a median value of 30% regardless of profession, years of experience, and self-assessed ability about visual estimation. This study highlights that assessments of patients' conditions can be partially based on methods often demonstrated to be inaccurate. Inaccurate visual estimation of blood loss might endanger patient safety.

The use of a screening scale improves the recognition of delirium in older patients after cardiac surgery-A retrospective observational study

AIMS AND OBJECTIVES

To analyse postoperative delirium (POD) in clinical practice after cardiac surgery, how it is detected and documented and if the use of a screening scale improves the detection rate.

BACKGROUND

Cardiac surgery is considered a routine procedure with few complications. However, POD remains a concern, although often being overlooked in clinical practice.

DESIGN

Retrospective observational analysis.

METHODS

Patients 70 years and older with POD (n = 78) undergoing cardiac surgery were included in the study. Discharge summaries of both nurses and physicians were reviewed together with the clinical database for information about POD, to be compared with symptom screening using the Nursing Delirium Screening Scale (Nu-DESC). A quantitative content analysis was used for the review of discharge summaries, with a coding scheme adopted from the Nu-DESC method. The STROBE checklist was followed.

RESULTS

In discharge summaries, 41 of the 78 POD patients were correctly recognised, and 22 of these were identified in the clinical database. Screening by the Nu-DESC identified delirium at a measurably higher rate, 56/78 patients. The review of discharge summaries showed that patients expressing "inappropriate behaviour" was the most easily identified sign for POD for both nurses and physicians.

CONCLUSIONS

Healthcare professionals underdiagnose delirium after cardiac surgery, with a low detection rate described in both discharge summaries and in the clinical database. Recognition of delirium improved when Nu-DESC was used for systematic screening.

RELEVANCE TO CLINICAL PRACTICE

This study emphasises the need for better screening for the detection of delirium in daily clinical practice.

Cardiopulmonary bypass prime composition: beyond crystalloids versus colloids

INTRODUCTION

In the literature addressing cardiopulmonary bypass (CPB) prime composition, there is a considerable lack of discussion concerning plasma osmolality changes induced by using a hyperosmolar prime. With this study, we try to determine the magnitude and temporal relationship of plasma osmolality changes related to the use of a hyperosmolar CPB prime.

METHOD

In this prospective observational study performed in a university hospital setting, we enrolled thirty patients scheduled for elective coronary bypass surgery. Plasma osmolality was analysed on eight occasions. A hyperosmolar CPB prime was used.

RESULTS

Analyses of the perioperative plasma osmolality on eight occasions gave the following results: the preoperative osmolality level was normal (297±4 mOsm/kg); a significant increase to 322±17 mOsm/kg (p<0.001) was observed at the commencement of CPB and remained elevated after 30 minutes (310±4 mOsm/kg) and throughout the procedure (309±4 mOsm/kg); the osmolality level returned to 291±5 mOsm/kg on day 1 postoperatively and remained normal the following day (291±6 mOsm/kg).

CONCLUSIONS

Use of hyperosmolar CPB prime resulted in a dramatic and instant elevation of the plasma osmolality. Rapid changes in plasma osmolality are associated with organ dysfunction (e.g. osmotic demyelination syndrome), therefore, effects on plasma osmolality related to the CPB prime composition should be recognised. Influence on organ function and clinical outcome warrants further investigations. - Clinical Trials.gov (NCT03060824). Changes in Plasma Osmolality Related to the Use of Cardiopulmonary Bypass With Hyperosmolar Prime. URL: https://clinicaltrials.gov/ct2/show/NCT03060824?term=cpb&cond=osmolality&rank=1.

Validation of the confusion assessment method in detecting postoperative delirium in cardiac surgery patients

BACKGROUND

Early detection, prevention, and treatment of delirium after cardiac surgery are important for quick postoperative recovery. The Confusion Assessment Method (CAM) may be an easy-to-use instrument for detecting delirium in clinical practice.

OBJECTIVES

To compare the congruent validity of the CAM with the results from repeated assessments by using a combination of the Organic Brain Syndrome Scale and the Mini-Mental State Examination according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition, Text Revision) criteria for delirium.

METHODS

Patients aged 70 years or older undergoing cardiac surgery were assessed on postoperative days 1 and 4, and the 2 diagnostic methods were compared. The sensitivity and specificity of the CAM were examined. The reference method allowed categorization of delirium into subgroups of psychomotor activities and psychiatric symptom profiles, which were compared with the CAM results.

RESULTS

Postoperative delirium was diagnosed in 78 of 141 patients (55.3%). According to the CAM, 59 patients (41.8%) were categorized as delirious, 53 correctly. Thus, the sensitivity was 68% and the specificity was 90%, indicating false-negative rather than false-positive observations.

CONCLUSION

Patients with psychomotor hyperactivity and mixed psychotic-emotional symptoms were more likely to have delirium detected via the CAM than were patients with less obvious clinical manifestations of delirium. Repetitive cognitive testing and psychogeriatric experience are probably necessary to improve the results obtained with the CAM.

Experiences of undergoing cardiac surgery among older people diagnosed with postoperative delirium: one year follow-up

Background

Cardiovascular disease is common among old people and many undergo cardiac surgery. Scientific knowledge is available on cardiac surgery from several perspectives. However, we found few studies focusing on older patients’ experiences of cardiac surgery. The aim of this study was to illuminate experiences of undergoing cardiac surgery among older people diagnosed with postoperative delirium, a one year follow-up.

Methods

Qualitative interviews were conducted with 49 participants (aged ≥70 years) diagnosed with delirium after cardiac surgery. Data were collected in Sweden during 2010 through individual, semi-structured interviews in participants’ homes one year after surgery. The interviews were analyzed using qualitative content analysis.

Results

Four themes with sub-themes were formulated: Feeling drained of viability includes having a body under attack, losing strength and being close to death. Feeling trapped in a weird world describes participants having hallucinations, being in a nightmare and being remorseful for their behavior. Being met with disrespect includes feeling disappointed, being forced, and feeling like cargo. On the other hand, Feeling safe, including being in supportive hands and feeling grateful, points to participants’ experiences of good care and the gift of getting a second chance in life.

Conclusions

Even one year after cardiac surgery, participants described in detail feelings of extreme vulnerability and frailty. They also had felt completely in the hands of the health care professionals. Participants described experiences of hallucinations and nightmares during hospitalization. Cardiac surgery was a unique, fearful, traumatic and unpleasant experience yet could also include pleasant or rewarding aspects. It seems that health care professionals need deeper knowledge on postoperative delirium in order to prevent, detect and treat delirium to avoid and relieve the suffering these experiences might cause.

Delirium after cardiac surgery: incidence and risk factors

OBJECTIVES

Delirium after cardiac surgery is a problem with consequences for patients and healthcare. Preventive strategies from known risk factors may reduce the incidence and severity of delirium. The present aim was to explore risk factors behind delirium in older patients undergoing cardiac surgery with cardiopulmonary bypass.

METHODS

Patients (≥70 years) scheduled for routine cardiac surgery were included (n = 142). The patients were assessed and monitored pre-/postoperatively, and delirium was diagnosed from repeated assessments with the Mini-Mental State Examination and the Organic Brain Syndrome Scale, using the DSM-IV-TR criteria. Variables were analysed by uni-/multivariable logistic regression, including both preoperative variables (predisposing) and those extracted during surgery and in the early postoperative period (precipitating).

RESULTS

Delirium was diagnosed in 78 patients (54.9%). Delirium was independently associated with both predisposing and precipitating factors (P-value, odds ratio, upper/lower confidence interval): age (0.036, 1.1, 1.0/1.2), diabetes (0.032, 3.5, 1.1/11.0), gastritis/ulcer problems (0.050, 4.0, 1.0/16.1), volume load during operation (0.001, 2.8, 1.5/5.1), ventilator time in ICU (0.042, 1.2, 1.0/1.4), highest temperature recorded in ICU (0.044, 2.2, 1.0/4.8) and sodium concentration in ICU (0.038, 1.2, 1.0/1.4).

CONCLUSIONS

Delirium was common among older patients undergoing cardiac surgery. Both predisposing and precipitating factors contributed to delirium. When combined, the predictive strength of the model improved. Preventive strategies may be considered, in particular among the precipitating factors. Of interest, delirium was strongly associated with an increased volume load during surgery.