Magnesium sulphate intravenously reduces tachycardia side-effects of ß2-agonists.

Intravenous magnesium sulphate allows safer intravenous ß2-agonist delivery in acute-severe and life-threatening asthma attacks https://bit.ly/3veUpfC.

Safety and efficacy of tetrastarches in surgery and trauma: a systematic review and meta-analysis of randomised controlled trials.

BACKGROUND: Hydroxyethyl starch (HES) 130 is a frequently used fluid to replace intravascular losses during surgery or trauma. In the past years, several trials performed in critically ill patients have raised questions regarding the safety of this product. Our aim in this meta-analysis was to evaluate the safety and efficacy of 6% HES during surgery and in trauma. METHODS: This systematic review and meta-analysis was registered at PROSPERO (CRD42018100379). We included 85 fully published articles from 1980 to June 2018 according to the protocol and three additional recent articles up to June 2020 in English, French, German, and Spanish reporting on prospective, randomised, and controlled clinical trials applying volume therapy with HES 130/0.4 or HES 130/0.42, including combinations with crystalloids, to patients undergoing surgery. Comparators were albumin, gelatin, and crystalloids only. A meta-analysis could not be performed for the two trauma studies as there was only one study that reported data on endpoints of interest. RESULTS: Surgical patients treated with HES had lower postoperative serum creatinine (P<0.001) and showed no differences in renal dysfunction, renal failure, or renal replacement therapy. Although there was practically no further difference in the colloids albumin or gelatin, the use of HES improved haemodynamic stability, reduced need for vasopressors (P<0.001), and decreased length of hospital stay (P<0.001) compared with the use of crystalloids alone. CONCLUSIONS: HES was shown to be safe and efficacious in the perioperative setting. Results of the present meta-analysis suggest that when used with adequate indication, a combination of intravenous fluid therapy with crystalloids and volume replacement with HES as colloid has clinically beneficial effects over using crystalloids only.

Achieving proficiency in rigid bronchoscopy-a study in manikins.

BACKGROUND: Rigid bronchoscopy may be used to relieve acute airway obstruction following induction of anaesthesia and is a recommended option for management of the difficult airway. The ability of anaesthetists to perform rigid bronchoscopy has not been reported. We sought to explore the acquisition of procedural skill in rigid bronchoscopy by anaesthesiologists in a manikin. METHODS: In a prospective interventional study, participants were asked to perform 40 rigid bronchoscopies in a TruCorp AirSim Advance airway manikin, configured to a randomised sequence of easy or difficult laryngoscopic grades to which the participants were blinded. The primary outcome was stabilisation (the attempt after which no further reduction in procedural time occurred). Dental injury and oesophageal intubation were also recorded. Forty anaesthesiologists and 40 unskilled controls (without laryngoscopic skills) participated. RESULTS: In the easy model, stabilisation occurred at attempt 8 in the anaesthesiology group and 10 in the unskilled controls. In the difficult model, stabilisation occurred at attempt 10 in both groups. Dental injury was less common in the anaesthesiology group. The proportion of participants achieving procedural competency did not differ between groups in either the easy (35/40 vs. 30/40) or difficult model (32/40 vs. 25/40). CONCLUSIONS: This study shows that the technical skill of rigid bronchoscopy can be acquired within 10 repetitions in a manikin model. As procedural competence and complication frequency vary with the laryngoscopic grade of the model, both easy and difficult configurations should be used for training. Advanced laryngoscopic skills are not required prior to training in this technique.

Perioperative administration of buffered versus non-buffered crystalloid intravenous fluid to improve outcomes following adult surgical procedures: a Cochrane systematic review.

BACKGROUND: Buffered intravenous fluid preparations contain substrates to maintain acid-base status. The objective of this systematic review was to compare the effects of buffered and non-buffered fluids administered during the perioperative period on clinical and biochemical outcomes. METHODS: We searched MEDLINE, EMBASE, CINAHL and the Cochrane Library until May 2017 and included all randomised controlled trials that evaluated buffered versus non-buffered fluids, whether crystalloid or colloid, administered to surgical patients. We assessed the selected studies for risk of bias and graded the level of evidence in accordance with Cochrane recommendations. RESULTS: We identified 19 publications of 18 randomised controlled trials, totalling 1096 participants. Mean difference (MD) in postoperative pH was 0.05 units lower immediately following surgery in the non-buffered group (12 studies of 720 participants; 95% confidence interval (CI) 0.04 to 0.07; I 2 = 61%). This difference did not persist on postoperative day 1. Serum chloride concentration was higher in the non-buffered group at the end of surgery (10 trials of 530 participants; MD 6.77 mmol/L, 95% CI 3.38 to 10.17). This effect persisted until postoperative day 1 (5 trials of 258 participants; MD 8.48 mmol/L, 95% CI 1.08 to 15.88). Quality of this evidence was moderate. We identified variable protocols for fluid administration and total volumes of fluid administered to patients intraoperatively. Outcome data was variably reported at disparate time points and with heterogeneous patient groups. Consequently, the effect size and overall confidence interval was reduced, despite the relatively low inherent risk of bias. There was insufficient evidence on the effect of fluid composition on mortality and organ dysfunction. Confidence intervals of this outcome were wide and the quality of evidence was low (3 trials of 276 participants for mortality; odds ratio (OR) 1.85, 95% CI 0.37 to 9.33; I 2 = 0%). CONCLUSIONS: Small effect sizes for biochemical outcomes and lack of correlated clinical follow-up data mean that robust conclusions on major morbidity and mortality associated with buffered versus non-buffered perioperative fluid choices are still lacking. Buffered fluid may have biochemical benefits, including a significant reduction in postoperative hyperchloraemia and metabolic acidosis.

Perioperative buffered versus non-buffered fluid administration for surgery in adults.

BACKGROUND: Perioperative fluid therapy influences clinical outcomes following major surgery. Fluid preparations may be based on a simple non-buffered salt solution, such as normal saline, or may be modified with bicarbonate or bicarbonate precursor buffers, such as maleate, gluconate, lactate or acetate, to better reflect the human physiological state. These latter fluids have theoretical advantages over normal saline in preventing hyperchloraemic acidosis. A number of clinical studies have now compared fluid preparations with and without a buffer to achieve a balanced electrolyte solution for perioperative fluid resuscitation. OBJECTIVES: To review the safety and efficacy of perioperative administration of buffered versus non-buffered fluids for plasma volume expansion or maintenance in adult patients undergoing surgery. SEARCH METHODS: We electronically searched the Cochrane Central Register of Controlled Trials (CENTRAL) (2011, Issue 4), MEDLINE (1966 to May 2011), EMBASE (1980 to May 2011), and CINAHL (1982 to May 2011). We handsearched conference abstracts and where possible, contacted leaders in the field. SELECTION CRITERIA: We only included randomized trials of buffered versus non-buffered intravenous fluids for perioperative fluid resuscitation. The trials with other forms of comparisons such as crystalloids versus colloids and colloids versus different colloids were excluded. We also excluded trials using hypertonic fluids and dextrose-based fluids. DATA COLLECTION AND ANALYSIS: Two authors independently extracted data and assessed the methodological quality of clinical trials. We resolved any disagreements by discussion. We contacted the trial authors to provide additional information where appropriate. We presented pooled estimates of the dichotomous outcomes as odds ratios (OR) and on continuous outcomes as mean differences, with 95% confidence intervals (CI). We analysed data on Review Manager 5.1 using fixed-effect models, and when heterogeneity was high (I² > 40%) random-effect models were used. MAIN RESULTS: We identified 14 publications reporting 13 trials or comparisons with a total of 706 participants. For many of the outcomes reported, there was significant clinical and statistical heterogeneity. The primary outcome of mortality at any time was reported in only three studies with a total of 267 patients. The mortality rate was 2.9% for the buffered fluids group and 1.5% for the non-buffered fluids group but this difference was not statistically significant. The Peto OR was 1.85 (95% CI 0.37 to 9.33, P = 0.45, I(2)= 0%). Organ dysfunction was only presented for renal impairment. There was no difference in renal insufficiency leading to renal replacement therapy between the buffered and non-buffered groups (OR 0.61, 95% CI 0.23 to 1.63, P = 0.32, I(2) = 0%). Markers of organ system failure as assessed by urine output, creatinine and its variables (for renal function), PaC0(2) (respiratory function) and postoperative nausea and vomiting (gastro-intestinal function) showed a statistically significant difference only in PaC0(2) levels. The mean difference was 1.18 with lower PaC0(2) levels in the non-buffered fluid group (95% CI 0.09 to 2.28, P = 0.03, I(2) = 0%) compared to the buffered fluid group.There was no difference in intraoperative blood loss nor the volumes of intraoperative red cell or fresh frozen plasma transfused between groups. There was an increase in platelet transfusion in the non-buffered group which was statistically significant after analysing the transformed data (log transformation because the data were highly skewed).A number of metabolic differences were noted. There was a difference in postoperative pH of 0.06 units, lower in the non-buffered fluid group (95% CI 0.04 to 0.08, P < 0.00001, I(2) = 74%). However, this difference was not maintained on postoperative day one. The non-buffered fluid group also had significantly greater base deficit, serum sodium and chloride levels.There was no difference demonstrated in length of hospital stay and no data were reported on cost or quality of life. AUTHORS' CONCLUSIONS: The administration of buffered fluids to adult patients during surgery is equally safe and effective as the administration of non-buffered saline-based fluids. The use of buffered fluids is associated with less metabolic derangement, in particular hyperchloraemia and metabolic acidosis. Larger studies are needed to assess robust outcomes such as mortality.

Place of the colloids in fluid resuscitation of the traumatized patient.

PURPOSE OF REVIEW: The examination of the recent literature aimed at analysing the most recent data that could affect decisions regarding the use of colloids in trauma resuscitation. RECENT FINDINGS: Animal data have generally shown a beneficial effect of colloids in trauma resuscitation, with improvements in capillary leak demonstrated in lung, intestine and brain. In most studies, hydroxyethyl starch resuscitation was more effective than crystalloid and decreased markers of inflammatory processes were observed. Brain injury in animals was attenuated with colloids. In uncontrolled haemorrhage, resuscitation with colloid increased bleeding and mortality.Human studies have also failed to confirm the suggestion that albumin resuscitation may be associated with a worse outcome in head injury. However, there is a strong suggestion that aggressive prehospital resuscitation, particularly with colloid, may be harmful. Studies in burns have consistently shown an improvement in the tendency to fluid overload with the inclusion of colloid in the resuscitation strategy, but so far no outcome benefit has been shown.Two studies of general trauma resuscitation have shown apparent benefit from the use of HES in early resuscitation with reductions in mortality and in renal injury. SUMMARY: Recent trauma studies provide ongoing, but not conclusive, evidence of a benefit from colloid resuscitation in trauma.

Colloids and crystalloids: does it matter to the kidney?

PURPOSE OF REVIEW: To highlight some of the recent key issues surrounding crystalloid and colloid fluid management of critically ill patients. RECENT FINDINGS: Significant developments have been made in the understanding of ionic balance of fluids and their effects on acid-base, the role of hydration and overhydration, alkalinization of fluids in patients at high risk for contrast induced nephropathy, and finally the role of colloids in acute kidney injury. SUMMARY: Despite hydration remaining a key principle in fluid management in many patients, volume overload is of considerable concern. Recent evidence also suggests that balanced electrolyte formulations are preferable to saline-based formulations in a variety of clinical settings. Furthermore, alkalinization of fluids is protective in the setting of contrast-induced nephropathy. Oncotic load appears to be the most important factor in acute kidney injury associated with colloid fluid therapy.

Hydroxyethyl starches: different products--different effects.

With the development of a new generation of hydroxyethyl starches (HES), there has been renewed interest in their clinical potential. High doses of first- and second-generation HES were associated with adverse effects on renal function, coagulation, and tissue storage, thereby limiting their clinical applicability. Newer HES products have lower molar substitution and in vivo molecular weight, resulting in more rapid metabolism and clearance. In this review article, the differences between HES generations are highlighted, with particular emphasis on the improved safety profile of the third generation products. These improvements have been achieved with no loss of efficacy, and they contradict the assumption that efficacy of HES solutions is directly linked to plasma concentration. The impact of source material on structure and pharmacokinetics is highlighted, and the role of the carrier solution is critically assessed.

The role of tetrastarches for volume replacement in the perioperative setting.

PURPOSE OF REVIEW: Current opinion in perioperative fluid therapy suggests that the use of colloids to achieve haemodynamic optimization may result in improved clinical outcomes. This has focused interest on the colloid solutions, particularly on the newest of these, the tetrastarches. This review will address the advantages and disadvantages of the starch solutions with particular emphasis on the advantages offered by the tetrastarches, as these products, which have been widely used in Europe for a number of years, have recently been released in the United States. RECENT FINDINGS: The tetrastarches have a molar substitution of 0.4, compared with the older hetastarches that had a molar substitution of 0.7. This results in a lower in-vivo molecular weight leading to more rapid clearance of the starch particles and a reduced incidence of adverse effects such as coagulation disorders and skin itching. It is probable that the more rapidly degradable tetrastarch also decreases, or possibly eliminates, the risk of renal dysfunction that has been associated with some of the earlier starch products. SUMMARY: Tetrastarch represents a substantial advance in colloid therapy, offering good volume effectiveness with a very low risk of adverse effects.

The coagulation changes induced by rapid in vivo crystalloid infusion are attenuated when magnesium is kept at the upper limit of normal.

BACKGROUND: Rapid crystalloid infusion enhances coagulation, regardless of electrolytes, pH or osmolality, an effect thought to be related to deep vein thrombosis and other clot formations. Altered serum magnesium may play a role in the balance of coagulation. In this in vivo study we investigated the coagulation response to rapid hemodilution when serum magnesium is maintained or partially increased. METHODS: Twenty-five healthy volunteers were investigated on three occasions, randomly receiving normal saline, Balsol (magnesium 1.5 g/L), and Balsol plus additional magnesium (magnesium 3.0 g/L). Investigators were blinded to the solution's identity. Baseline blood samples were taken measuring hematocrit, serum magnesium, and thrombelastography (TEG), whereafter 14 mL/kg (20% blood volume) was infused over 30 min, followed by a second blood sample. All results were compared to their own baseline values using ANOVA with LSD post hoc significance testing. RESULTS: All groups had a similar postdilutional hematocrit decrease, with significant magnesium reduction in the saline group (0.81 +/- 0.07 to 0.74 +/- 0.07 (approximately -8.6%) (P < 0.003)), no change in the Balsol group and significant increase in the Balsol + magnesium group (0.84 +/- 0.07 to 0.99 +/- 0.06 (approximately 17.9%) (P < 0.001)). Postdilutional TEG results reflected no significant change from control in the Balsol + magnesium group. Both of the other two groups had statistically significant increased clot formation (reaction time to onset of clotting and clotting time shortened; alpha-angle increased). CONCLUSIONS: Rapid hemodilution-induced coagulation may be partially due to decreased magnesium, and the effect is attenuated by maintaining magnesium at the upper limit of normal. Crystalloid resuscitation fluids should possibly contain higher magnesium levels, around 3 mmol/L.

Calcium supplementation of saline-based colloids does not produce equivalent coagulation profiles to similarly balanced salt preparations.

OBJECTIVES: The primary objective of this study was to test the hypothesis that calcium alone does not account for the observed coagulation differences between saline-based and balanced electrolyte IV fluid preparations. DESIGN: Controlled, nonblinded, in vitro observational study. SETTING: University-based anesthesia research laboratory. PARTICIPANTS: Ten healthy volunteers. INTERVENTIONS: The volunteers donated fresh blood for in vitro 40% and 60% dilution with 6 intravenous fluid preparations (lactated Ringer's solution, human albumin solution, and 4 hydroxyethyl starch preparations). All saline-based fluids were supplemented with calcium chloride to obtain ionized concentrations >or=1.0 mmol/L. MEASUREMENTS AND MAIN RESULTS: After dilution of the fresh blood with the study fluids, samples were analyzed by using the Thrombelastograph. Three colloid preparations produced minimal coagulation derangement, even at 60% dilution (human albumin solution, tetrastarch in saline, and pentastarch in balanced electrolyte solution), whereas pentastarch in saline and hetastarch in balanced electrolyte produced a mildly hypocoagulable state at 60% dilution. CONCLUSIONS: The different coagulation profiles between the 2 pentastarch preparations, as well as similar profiles of pentastarch in saline and hetastarch in balanced electrolyte solution, suggest that calcium is not solely responsible for previously observed effects.

A head-to-head comparison of the in vitro coagulation effects of saline-based and balanced electrolyte crystalloid and colloid intravenous fluids.

Both fluid composition (e.g., type of hydroxyethyl starch) and formulation (e.g., saline or balanced salt carrier solution) may alter whole blood coagulation. We therefore enrolled 10 healthy volunteers to test ex vivo, thrombelastograph-based blood coagulation differences of eight crystalloid and colloid solutions at 20%, 40%, and 60% dilutions. Saline and lactated Ringer's solution produced a hypercoagulable state at 20%-40% dilutions. Saline, hetastarch in saline, pentastarch in saline, tetrastarch in saline, and human albumin solutions all produced a hypocoagulable state at 60% dilution. Hetastarch in saline also produced a hypocoagulable state at 40% dilution. The larger molecular weight starches produced more intense coagulation abnormalities than the medium molecular weight compounds formulated similarly (i.e., suspended in saline or balanced salt solution). The balanced salt solutions caused fewer coagulation abnormalities, especially pentastarch in balanced salt solution. This balanced salt pentastarch preparation produced the least derangement of coagulation of the colloid solutions at all dilutions, causing hypercoagulability at the lower dilutions and minimal coagulation derangement at 60% dilution. These data support the theory that smaller molecular weight hydroxyethyl starches and colloids suspended in balanced salt solutions preserve coagulation better than large molecular weight starches and saline-based colloids, as judged by thrombelastography.

Dose-response relationship between plasma ionized calcium concentration and thrombelastography.

OBJECTIVES: To establish the threshold value for calcium at which coagulation commenced and to investigate the range over which changes in ionized calcium influenced coagulation. DESIGN: Controlled, nonblinded, in vitro observational study. SETTING: The study was conducted in a university-based laboratory. PARTICIPANTS: Blood was obtained from healthy volunteers. INTERVENTIONS: One hundred samples of citrated blood were recalcified using varying quantities of 10% calcium chloride solution. Heparinized samples from the recalcified blood were obtained for measurement of ionized calcium concentration (Ca(2+)). MEASUREMENTS AND RESULTS: Coagulation of the recalcified samples was analyzed using thrombelastography. The ionized calcium concentration in recalcified blood was measured using a calcium electrode in a blood gas analyzer. No sample with a Ca(2+) < 0.33 mmol/L showed any clot formation. Normal coagulation measures were obtained in almost all samples in which the Ca(2+) was >0.56 mmol/L. Final clot strength appeared to be independent of Ca(2+) once the threshold value of 0.33 mmol/L was exceeded. CONCLUSIONS: Ca(2+) of <0.33 mmol/L is necessary to prevent coagulation. Ca(2+) > 0.56 is unlikely to be the cause of coagulation abnormalities during surgical procedures in which calcium metabolism is deranged. Between these values, Ca(2+) may exert an effect on the rate of clot formation, but final clot strength should be unaffected.

Aspiration prevented by the ProSeal laryngeal mask airway: a case report.

PURPOSE: To describe a case of intraoperative passive regurgitation where the ProSeal laryngeal mask airway (PLMA) successfully protected the airway from the respiratory tract. CLINICAL FEATURES: A 32-yr-old man was electively scheduled for change of dressings and application of plaster of Paris to both legs. A size 5 PLMA was inserted on the first attempt and the patient allowed to breathe spontaneously. Twenty-five minutes into the procedure brown fluid was noticed in the drainage tube of the mask. There was no change in respiratory pattern nor any evidence of coughing retching or vomiting. Twenty-five millilitres of fluid were suctioned out of the tube which tested positive for acid. The PLMA was left in place and the procedure continued uneventfully. After removal of the mask pH testing showed the dorsum of the mask to have a pH of 7 and the ventrum/bowl of the mask to be dry with a pH of 7. The patient had no respiratory symptoms in the recovery room and the postoperative course was uneventful. CONCLUSIONS: This case illustrates that passive regurgitation can occur unexpectedly intraoperatively and shows that the PLMA can protect the airway during such an event by allowing the regurgitated fluid to pass up the drainage tube without leaking into the glottis.