Mark Blunt

Effect of a perioperative, cardiac output-guided hemodynamic therapy algorithm on outcomes following major gastrointestinal surgery: a randomized clinical trial and systematic review

IMPORTANCE Small trials suggest that postoperative outcomes may be improved by the use of cardiac output monitoring to guide administration of intravenous fluid and inotropic drugs as part of a hemodynamic therapy algorithm. OBJECTIVE To evaluate the clinical effectiveness of a perioperative, cardiac output-guided hemodynamic therapy algorithm. DESIGN, SETTING, AND PARTICIPANTS OPTIMISE was a pragmatic, multicenter, randomized, observer-blinded trial of 734 high-risk patients aged 50 years or older undergoing major gastrointestinal surgery at 17 acute care hospitals in the United Kingdom. An updated systematic review and meta-analysis were also conducted including randomized trials published from 1966 to February 2014. INTERVENTIONS Patients were randomly assigned to a cardiac output-guided hemodynamic therapy algorithm for intravenous fluid and inotrope (dopexamine) infusion during and 6 hours following surgery (n=368) or to usual care (n=366). MAIN OUTCOMES AND MEASURES The primary outcome was a composite of predefined 30-day moderate or major complications and mortality. Secondary outcomes were morbidity on day 7; infection, critical care-free days, and all-cause mortality at 30 days; all-cause mortality at 180 days; and length of hospital stay. RESULTS Baseline patient characteristics, clinical care, and volumes of intravenous fluid were similar between groups. Care was nonadherent to the allocated treatment for less than 10% of patients in each group. The primary outcome occurred in 36.6% of intervention and 43.4% of usual care participants (relative risk [RR], 0.84 [95% CI, 0.71-1.01]; absolute risk reduction, 6.8% [95% CI, -0.3% to 13.9%]; P = .07). There was no significant difference between groups for any secondary outcomes. Five intervention patients (1.4%) experienced cardiovascular serious adverse events within 24 hours compared with none in the usual care group. Findings of the meta-analysis of 38 trials, including data from this study, suggest that the intervention is associated with fewer complications (intervention, 488/1548 [31.5%] vs control, 614/1476 [41.6%]; RR, 0.77 [95% CI, 0.71-0.83]) and a nonsignificant reduction in hospital, 28-day, or 30-day mortality (intervention, 159/3215 deaths [4.9%] vs control, 206/3160 deaths [6.5%]; RR, 0.82 [95% CI, 0.67-1.01]) and mortality at longest follow-up (intervention, 267/3215 deaths [8.3%] vs control, 327/3160 deaths [10.3%]; RR, 0.86 [95% CI, 0.74-1.00]). CONCLUSIONS AND RELEVANCE In a randomized trial of high-risk patients undergoing major gastrointestinal surgery, use of a cardiac output-guided hemodynamic therapy algorithm compared with usual care did not reduce a composite outcome of complications and 30-day mortality. However, inclusion of these data in an updated meta-analysis indicates that the intervention was associated with a reduction in complication rates. TRIAL REGISTRATION isrctn.org Identifier: ISRCTN04386758.

Out-of-hours consultant cover and case-mix-adjusted mortality in intensive care

UK national recommendations include 24 h non-resident availability of consultants with a sessional commitment to intensive care (intensivists). We tested whether continual availability of such specialists improved standardised mortality ratios compared with non-specialist cover by anaesthetists who also cover other hospital departments. The case-mix-adjusted hospital mortality of intensive-care patients improved significantly in the intensivist group compared with the non-specialist group (standardised mortality ratios 0.81 vs 1.11 ratio 0.73 [95% CI 0.55-0.97]). Introduction of 24 h intensivist cover, therefore, seems to improve outcomes in intensive-care units.

A low-volume, low-pressure tracheal tube cuff reduces pulmonary aspiration*

Objective:Leakage of fluid from the subglottic space to the lungs occurs along the longitudinal folds within the wall of an inflated high-volume, low-pressure (HVLP) cuff. The low-volume, low-pressure (LVLP) cuff does not have these folds yet allows for convenient and reliable control of tracheal wall pressure. Pulmonary aspiration during anesthesia has been linked with postoperative pneumonia and during critical illness causes ventilator-associated pneumonia. Design:Prospective, blinded, randomized controlled trial; prospective observational study; and benchtop models. Setting:Department of Anaesthesia and Critical Care, Queen Elizabeth Hospital. Patients:Anesthetized patients (n = 38) and critically ill patients with either an LVLP or HVLP cuffed tracheostomy tube following swallow assessments (n = 67). Interventions:The LVLP cuff was compared with HVLP cuffs for leakage of dye placed in the subglottic space to the tracheobronchial tree in a rigid tracheal model and a benchtop pig trachea model (before and after a standardized cuff movement). Measurements and Main Results:In the rigid tracheal model, the incidence of leakage was 0% in the LVLP group and 100% in the HVLP group (p < .01). Dye leakage in the pig tracheal model with HVLP cuffs was 44% before tube movement, increasing to 79% afterward. The LVLP cuff did not leak in the pig tracheal model. Dye leakage in anesthetized patients was 0% before movement and 5% after in the LVLP group and in the HVLP group 22% increasing to 67% after movement (p < .001). Forty-nine percent of swallow assessments were scored as failed in the critical care patients with HVLP tracheostomy tube cuffs, and there were no episodes of aspiration following swallow assessment in the LVLP group (p < .05). Conclusions:The LVLP cuffed tracheal and tracheostomy tubes reduced pulmonary aspiration in the benchtop models and in anesthetized and critically ill patients. The single failure of the LVLP cuff in the anesthesia group was probably associated with accidental endobronchial intubation following tube movement.

Gel Lubrication of the Tracheal Tube Cuff Reduces Pulmonary Aspiration

Background Leakage of fluid occurs along the longitudinal folds within the wall of an inflated high-volume, low-pressure cuff. Theoretically, lubrication of the cuff with a water-soluble gel might prevent aspiration by plugging the channels in the cuff wall. Pulmonary aspiration during anesthesia has been linked with postoperative pneumonia and during critical illness causes ventilator-associated pneumonia. Methods Lubricated cuffs were compared with nonlubricated cuffs for leakage of dye placed in the subglottic space to the tracheobronchial tree in a benchtop model (n = 5) and in a prospective double-blinded randomized controlled trial of anesthetized patients (n = 36). The duration of the efficacy of the lubricant was determined in a prospective open observational study of critically ill patients with tracheostomies (n = 9). Dye was detected clinically by dye coloration of secretions during tracheal suctioning. Results In the benchtop model the incidence of leakage was 0% in the lubrication group and 100% in the nonlubrication group (P < 0.01). Dye leakage in anesthetized patients was 11% in the lubrication group and 83% in the nonlubrication group (P < 0.0001). In the critically ill patients with lubricated cuffed tracheostomy tubes, leakage first occurred after a median period of 48 h (range, 24–120 h). Conclusions Cuff lubrication with a water-soluble gel reduces pulmonary aspiration in anesthetized patients. In the critically ill patient with a tracheostomy the protective effect is lost after 24–120 h.

Preoxygenation and apneic oxygenation using Transnasal Humidified Rapid-Insufflation Ventilatory Exchange for emergency intubation.

PURPOSE Hypoxia is one of the leading causes of anesthesia-related injury. In response to the limitations of conventional preoxygenation, Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) has been used as a method of providing both preoxygenation and apneic oxygenation during intubation. MATERIALS AND METHODS In this prospective, observational study, THRIVE was introduced in a critical care unit (CCU), operating room (OR), and emergency department (ED) during emergency intubation of patients at high risk of hypoxia. Linear regression analysis tested for correlation between apnea time or body mass index and hemoglobin saturation (Spo2). RESULTS Across 71 sequential patients, the interquartile range for apnea time and decrease in Spo2 were 60 to 125 seconds and 0% to 3%, respectively. Significant desaturation occurred in 5 (7%) patients. There was no evidence of correlation between apnea time or body mass index and Spo2 (R2=0.04 and 0.08 for CCU/ED and OR and 0.01 and 0.04 CCU/ED and OR, respectively). There were no complications reported from using THRIVE. CONCLUSIONS This study demonstrated that preoxygenation and apneic oxygenation using THRIVE were associated with a low incidence of desaturation during emergency intubation of patients at high risk of hypoxia in the CCU, OR, and ED. THRIVE has the potential to minimize the risk of hypoxia in these patient groups.

The pressure exerted on the tracheal wall by two endotracheal tube cuffs: A prospective observational bench-top, clinical and radiological study

BackgroundThe Lotrach endotracheal tube has a unique low-volume, low-pressure (LVLP) cuff, which has been designed to prevent pressure injury to the tracheal wall. We aimed to estimate the pressure exerted on the tracheal wall by the LVLP cuff and a conventional cuff in a bench-top, clinical and radiological study.MethodIn the bench-top study, a model trachea was intubated with the LVLP cuff and the conventional cuff. The cuff pressure was controlled using a constant pressure device. We assessed the pressure exerted on the tracheal wall by measuring the ability of the cuffs to support a column of water using a standard protocol. In the clinical study, we tested the ability of both cuffs to prevent air leak during a staged recruitment manoeuvre. In the radiological study, we recorded the degree of anatomical distortion of the trachea from both cuffs in the antero-posterior (AP) and transverse tracheal diameters. We performed statistical analysis using non-inferiority tests.ResultsIn the bench-top study, the LVLP cuff achieved a plateau at a mean height of 25.2 cmH2O (SD 0.34). In contrast, the conventional cuff failed to maintain any water above the cuff and a plateau could not be measured. In the clinical study, the mean pressure at which air leak occurred was 30.0 +/- 0.8 cmH2O (SD 3.8) using the LVLP cuff and 32.4 +/- 0.7 cmH2O (SD 3.0) using the conventional cuff. In the radiological study, the mean degree of anatomical distortion of the trachea in AP and transverse tracheal diameter was 2.9 +/- 2.2 mm (SD 2.1) and 1.8 +/- 1.4 mm (SD 1.4) using the LVLP cuff and 4.4 +/- 1.3 mm (SD 1.4) and 2.6 +/- 1.5 mm (SD 1.6) using the conventional cuff.ConclusionsThe bench-top and clinical studies both demonstrated that the LVLP cuff exerted approximately 30 cmH2O of pressure on the tracheal wall. These results are supported by our radiological study. We conclude that the LVLP cuff exerts an acceptable amount of pressure on the tracheal wall when it is operated at the recommended intracuff pressure.

Emergency capnography monitoring: comparing ergonomic design of intensive care unit ventilator interfaces and specific training of staff in reducing time to activation

Modern ventilators provide capnography monitoring in patients with tracheal tubes, in compliance with national and international recommendations. This technology is often not used when patients’ lungs are non‐invasively ventilated; however, it should be accessed immediately following tracheal intubation to confirm tube placement. This study assessed the effect of ventilation interface design on the speed with which capnography can be activated by comparing the Dräger Evita 4 and Dräger V500 before and after a specific training episode. We configured the V500 to have a capnography activation button on the front screen in contrast to the Evita 4 which requires a sequence of actions to access capnography monitoring. We used a randomised crossover design, measuring time to monitoring activation, and repeated the study after 3 months. Survival analysis showed significantly quicker activation associated with ventilator choice (V500, p < 0.0001) and training (p = 0.0058). The training improved activation speed with both machines, though this was only significant for the Evita 4 (p = 0.0097).

Keyboard cleanliness: A controlled study of the residual effect of chlorhexidine gluconate

A controlled trial of once daily cleaning of computer keyboards in an intensive care unit was performed comparing 2% chlorhexidine gluconate-70% isopropyl alcohol (CHG) and a chlorine dioxide-based product used as a standard in our hospital. A study before and after the introduction of once daily keyboard cleaning with CHG in the wider hospital was also completed. Cleaning with CHG showed a sustained and significant reduction in bacterial colony forming units compared with the chlorine dioxide-based product, demonstrating its unique advantage of maintaining continuous keyboard cleanliness over time.