Postoperative hypocalcaemia after elective bowel resections is - - PowerPoint PPT Presentation

Postoperative hypocalcaemia after elective bowel resections… is PlasmaLyte the culprit?

Dr R. Nichani, Dr D. Kelly (Consultant Anaesthetist and Intensivist) Dominic Wu (FY1 Anaesthetics)

Rationale

• Balanced solutions are the replacement intravenous fluids
• f choice for patients undergoing major elective surgery
• Our trust has replaced Hartmann’s with PlasmaLyte, a

calcium-free crystalloid, in February 2012

• Critical care directorates have anecdotally noticed an

increased incidence of “biochemical hypocalcaemia” in patients who are admitted to ICU/HDU

• We hypothesized that the change of intravenous fluid has

contributed to the low serum calcium level of patients on presentation to critical care

Methods

• Retrospective study
• Approved by the Local Research and Ethics Committee

as a Service Evaluation Project

• Population of interest were patients who underwent

elective major bowel resections between:

• August’11 – January’12 (Group A: Hartmann’s)
• August’12 – January’13 (Group B: Post-Plasmalyte)
• August’13 – January’14 (Group C: Post-Plasmalyte)

Outcomes of Interest

• Primary outcome
• Hypocalcaemia (Defined as Adj. Ca < 2.20mmol/L)
• Secondary outcomes
• Changes in serum albumin, magnesium and creatinine

Data collection

• Data synthesis
• Hospital Identifier, Gender and D.O.B. of patients who

underwent major bowel resections in Theatre 11 and 12 were collected using ORMIS (Theatre Management)

• Data extraction
• Biochemical results inc. total calcium, albumin, adjusted

calcium, magnesium and creatinine taken on the day of preoperative assessment and up to two days following the surgery were obtained via CyberLAB

Statistical Analysis

• Paired Students’ T Test*
• Difference of mean values within the same group
• One-way ANOVA Test**
• Difference of mean values between the three groups

* P value < 0.001 as statistical significant **A large F ratio (between-group variability/ within- group variability) indicates high statistical significance

• f mean variables between the three study groups

Results

Demographics Hartmann’s Plasmalyte 1 Plasmalyte 2 Number 75 81 69 Male:Female 47:28 44:37 25:44 Mean Age 64.8 65.8 67.3 Laparoscopic procedure Open procedure Not specified 44 19 12 39 24 18 37 13 19 Anterior Resection AP Resection Right hemicolectomy Left hemicolectomy Small bowel resection Miscellaneous 29 7 24 5 4 6 27 7 28 3 4 12 25 5 19 6 3 11

Blood parameters (mean ± SD) Hartmann’s Plasmalyte 1 Plasmalyte 2 Albumin (g/L) Pre-op 41.39 5.53 40.90 3.78 41.10 3.43 Day 0 30.72 5.26 29.44 5.37 31.83 3.89 Day 1 29.87 4.14 30.36 4.78 31.10 4.15 Day 2 30.18 4.28 30.09 5.06 31.04 4.15 Creatinine (mmol/L) Pre-op 81.81 30.09 78.33 20.04 77.06 17.80 Day 0 70.00 30.09 67.81 19.55 67.69 21.76 Day 1 75.70 24.01 73.28 22.04 69.88 17.91 Day 2 75.13 31.88 72.19 23.39 69.48 22.76

2.10 2.15 2.20 2.25 2.30 2.35 2.40 2.45 Pre-op Day 0 Day 1 Day 2 Adjusted Ca2+ (mmol/L)

Mean values of Adjusted Calcium

Hartmann's Plasmalyte 1 Plasmalyte 2

ANOVA

Preop Adj Calcium p=0.33, F = 1.123 Day 0 Adj Calcium p <000.1, F = 35.81 Day 1 Adj Calcium p<000.1, F = 48.21 Day 2 Adj Calcium p<000.1, F =17.37

Miscellaneous

0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 Day 0 Day 1 Day 2 Mg2+ (mmol/L)

Levels of Magnesium (No Baseline)

Hartmann's Plasmalyte 1 Plasmalyte 2

Discussion

• Trials comparing crystalloids and colloids in major

surgeries are all underpowered to determine clinical benefits and risks (Anesth Analg 2012;114:640 –51)

• The use of buffered fluids is associated with less

metabolic derangement, in particular hyperchloraemia and metabolic acidosis (Cochrane Database Syst Rev. 2012;12:CD004089)

• Observational studies of 31920 patients with plasmalyte

as replacement fluid on the day of major open abdominal surgery was associated with less postoperative morbidity than 0.9% saline (Ann Surg. 2012; 255(5):821-9.)

• No convincing evidence as to whether gluconate, acetate
• r lactate buffered solutions produces better postoperative
• utcomes following major abdominal surgery

• Effect of Different Crystalloid Solutions on Acid-Base

Balance and Early Kidney Function After Kidney Transplantation Anesthesia & Analgesia. 107(1):264- 269, July 2008

• Plasma acetate, gluconate and interleukin-6 profiles

during and after cardiopulmonary bypass: a comparison of Plasma-Lyte 148 with a bicarbonate- balanced solution. Crit Care. 2011;15(1):R21.

• A balanced view of balanced solutions. Critical Care

2010, 14:325

• Impact of Plasma-Lyte pH 7.4 on acid-base status and

hemodynamics in a model of controlled hemorrhagic

• shock. Clinics (Sao Paulo). 2011; 66(11): 1969–1974

• No study to date has compared postoperative calcium

changes between different crystalloid solutions

• Research question answered that the incidence of

biochemical hypocalcaemia has significantly risen since the change of crystalloid in our trust

• Our work is limited as supportive information are lacking
• Type and amount of peri-operative fluids used
• Levels of ionized Ca
• Clinical hypocalcaemia e.g. tetany, arrhythmia etc
• Whether patient received massive transfusion
• Whether Ca supplements had been given to patients

Limitations

Summary

• Incidence of biochemical hypocalcaemia is significantly

higher in surgical patients who received PlasmaLyte than Hartmann's following elective bowel resections