Preoperative preparation of children with upper respiratory tract infection: a focussed narrative review.

This review summarises the current evidence for the perioperative preparation in children with upper respiratory tract infections (URTI), including COVID-19 infection. URTI, including COVID-19 infection, are common and frequent in children who present for elective surgery. Children with URTI are at increased risk of perioperative respiratory adverse events. Perioperative respiratory adverse events are among the most serious and impactful consequences of paediatric anaesthesia, including cardiorespiratory arrest, and therefore present a significant challenge for the paediatric anaesthetist. This review addresses the pathophysiology and time course of URTI, including COVID-19. The evidence-based patient, anaesthetic, and surgical risk factors for perioperative respiratory adverse events are summarised. These risk factors work synergistically to determine individual patient risk and allow for risk stratification both clinically and with validated scoring systems. Evidence-based optimisation of modifiable respiratory risk factors can reduce the risk of perioperative bronchospasm. The evidence for the anaesthesia management options, including the timing and setting of surgery, experience of the paediatric anaesthetist, premedication, choice of airway device, choice of agent for induction and maintenance of anaesthesia, and deep vs awake tracheal extubation techniques along with a risk stratification framework are discussed.

Effect of infusion set replacement intervals on catheter-related bloodstream infections (RSVP): a randomised, controlled, equivalence (central venous access device)-non-inferiority (peripheral arterial catheter) trial.

BACKGROUND: The optimal duration of infusion set use to prevent life-threatening catheter-related bloodstream infection (CRBSI) is unclear. We aimed to compare the effectiveness and costs of 7-day (intervention) versus 4-day (control) infusion set replacement to prevent CRBSI in patients with central venous access devices (tunnelled cuffed, non-tunnelled, peripherally inserted, and totally implanted) and peripheral arterial catheters. METHODS: We did a randomised, controlled, assessor-masked trial at ten Australian hospitals. Our hypothesis was CRBSI equivalence for central venous access devices and non-inferiority for peripheral arterial catheters (both 2% margin). Adults and children with expected greater than 24 h central venous access device-peripheral arterial catheter use were randomly assigned (1:1; stratified by hospital, catheter type, and intensive care unit or ward) by a centralised, web-based service (concealed before allocation) to infusion set replacement every 7 days, or 4 days. This included crystalloids, non-lipid parenteral nutrition, and medication infusions. Patients and clinicians were not masked, but the primary outcome (CRBSI) was adjudicated by masked infectious diseases physicians. The analysis was modified intention to treat (mITT). This study is registered with the Australian New Zealand Clinical Trials Registry ACTRN12610000505000 and is complete. FINDINGS: Between May 30, 2011, and Dec, 9, 2016, from 6007 patients assessed, we assigned 2944 patients to 7-day (n=1463) or 4-day (n=1481) infusion set replacement, with 2941 in the mITT analysis. For central venous access devices, 20 (1·78%) of 1124 patients (7-day group) and 16 (1·46%) of 1097 patients (4-day group) had CRBSI (absolute risk difference [ARD] 0·32%, 95% CI -0·73 to 1·37). For peripheral arterial catheters, one (0·28%) of 357 patients in the 7-day group and none of 363 patients in the 4-day group had CRBSI (ARD 0·28%, -0·27% to 0·83%). There were no treatment-related adverse events. INTERPRETATION: Infusion set use can be safely extended to 7 days with resultant cost and workload reductions. FUNDING: Australian National Health and Medical Research Council.

Anesthetic considerations in children with asthma.

Due to the high prevalence of asthma and general airway reactivity, anesthesiologists frequently encounter children with asthma or asthma-like symptoms. This review focuses on the epidemiology, the underlying pathophysiology, and perioperative management of children with airway reactivity, including controlled and uncontrolled asthma. It spans from preoperative optimization to optimized intraoperative management, airway management, and ventilation strategies. There are three leading causes for bronchospasm (1) mechanical (eg, airway manipulation), (2) non-immunological anaphylaxis (anaphylactoid reaction), and (3) immunological anaphylaxis. Children with increased airway reactivity may benefit from a premedication with beta-2 agonists, non-invasive airway management, and deep removal of airway devices. While desflurane should be avoided in pediatric anesthesia due to an increased risk of bronchospasm, other volatile agents are potent bronchodilators. Propofol is superior in blunting airway reflexes and, therefore, well suited for anesthesia induction in children with increased airway reactivity.

Incidence, Risk Factors, and Outcomes of Intra-Abdominal Hypertension in Critically Ill Patients-A Prospective Multicenter Study (IROI Study).

OBJECTIVES: To identify the prevalence, risk factors, and outcomes of intra-abdominal hypertension in a mixed multicenter ICU population. DESIGN: Prospective observational study. SETTING: Fifteen ICUs worldwide. PATIENTS: Consecutive adult ICU patients with a bladder catheter. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Four hundred ninety-one patients were included. Intra-abdominal pressure was measured a minimum of every 8 hours. Subjects with a mean intra-abdominal pressure equal to or greater than 12 mm Hg were defined as having intra-abdominal hypertension. Intra-abdominal hypertension was present in 34.0% of the patients on the day of ICU admission (159/467) and in 48.9% of the patients (240/491) during the observation period. The severity of intra-abdominal hypertension was as follows: grade I, 47.5%; grade II, 36.6%; grade III, 11.7%; and grade IV, 4.2%. The severity of intra-abdominal hypertension during the first 2 weeks of the ICU stay was identified as an independent predictor of 28- and 90-day mortality, whereas the presence of intra-abdominal hypertension on the day of ICU admission did not predict mortality. Body mass index, Acute Physiology and Chronic Health Evaluation II score greater than or equal to 18, presence of abdominal distension, absence of bowel sounds, and positive end-expiratory pressure greater than or equal to 7 cm H2O were independently associated with the development of intra-abdominal hypertension at any time during the observation period. In subjects without intra-abdominal hypertension on day 1, body mass index combined with daily positive fluid balance and positive end-expiratory pressure greater than or equal to 7 cm H2O (as documented on the day before intra-abdominal hypertension occurred) were associated with the development of intra-abdominal hypertension during the first week in the ICU. CONCLUSIONS: In our mixed ICU patient cohort, intra-abdominal hypertension occurred in almost half of all subjects and was twice as prevalent in mechanically ventilated patients as in spontaneously breathing patients. Presence and severity of intra-abdominal hypertension during the observation period significantly and independently increased 28- and 90-day mortality. Five admission day variables were independently associated with the presence or development of intra-abdominal hypertension. Positive fluid balance was associated with the development of intra-abdominal hypertension after day 1.

Pharmacokinetics of Ceftolozane-Tazobactam during Prolonged Intermittent Renal Replacement Therapy.

BACKGROUND: Prolonged intermittent renal replacement therapy (PIRRT) eliminates many drugs, and without dosing data, for new antibiotics like ceftolozane/tazobactam, suboptimal concentrations and treatment failure are likely. OBJECTIVES: Herein, we describe the effect of PIRRT on the plasma pharmacokinetics of ceftolozane/tazobactam ad-ministered in a critically ill 55-year-old patient with a polymicrobial sternal wound osteomyelitis, including a multiresistant Pseudomonas aeruginosa. METHOD: Blood samples were taken over 4 days where the patient received a 7.5-h PIRRT treatment. One- and 2-compartment models were tested for ceftolozane and tazobactam separately, and the log-likelihood ratio and goodness-of-fit plots were used to select the final model. RESULTS: Two-compartment models were developed for ceftolozane and tazobactam separately and described significant differences in clearance of ceftolozane and tazobactam with and without PIRRT (8.273 vs. 0.393 and 8.020 vs. 0.767 L/h, respectively). CONCLUSIONS: A ceftolozane/tazobactam dose of 500 mg/250 mg appears to be sufficient to attain pharmacokinetic/pharmacodynamic targets during PIRRT while the manufacturer's recommended dosing of 100 mg/50 mg every 8 h was sufficient during non-PIRRT periods.

An update on the perioperative management of children with upper respiratory tract infections.

PURPOSE OF REVIEW: This review summarizes the current evidence for the management of children with recent upper respiratory tract infections (URTIs). Furthermore, the review includes management guidelines for children with URTIs. RECENT FINDINGS: Good history and clinical examination is sufficient in most children presenting with URTI. Testing for immune markers or preoperative nitric oxide measurement does not add any additional value. Preoperative bronchodilator administration, intravenous induction with propofol, and noninvasive airway management all reduce the occurrence of respiratory adverse events. SUMMARY: Most children can be safely anaesthetized even in the presence of an URTIs if the perioperative anaesthesia management is optimized. In this review article, we have included a management algorithm for children with URTI presenting for elective surgery.

Anesthesia and ventilation strategies in children with asthma: part I - preoperative assessment.

PURPOSE OF REVIEW: Asthma is a common disease in the pediatric population, and anesthetists are increasingly confronted with asthmatic children undergoing elective surgery. This first of this two-part review provides a brief overview of the current knowledge on the underlying physiology and pathophysiology of asthma and focuses on the preoperative assessment and management in children with asthma. This also includes preoperative strategies to optimize lung function of asthmatic children undergoing surgery. The second part of this review focuses on the immediate perioperative anesthetic management including ventilation strategies. RECENT FINDINGS: Multiple observational trials assessing perioperative respiratory adverse events in healthy and asthmatic children provide the basis for identifying risk factors in the patient's (family) history that aid the preoperative identification of at-risk children. Asthma treatment outside anesthesia is well founded on a large body of evidence. Optimization and to some extent intensifying asthma treatment can optimize lung function, reduce bronchial hyperreactivity, and minimize the risk of perioperative respiratory adverse events. SUMMARY: To minimize the considerable risk of perioperative respiratory adverse events in asthmatic children, a good understanding of the underlying physiology is vital. Furthermore, a thorough preoperative assessment to identify children who may benefit of an intensified medical treatment thereby minimizing airflow obstruction and bronchial hyperreactivity is the first pillar of a preventive perioperative management of asthmatic children. The second pillar, an individually adjusted anesthesia management aiming to reduce perioperative adverse events, is discussed in the second part of this review.

Anesthesia and ventilation strategies in children with asthma: part II - intraoperative management.

PURPOSE OF REVIEW: As asthma is a frequent disease especially in children, anesthetists are increasingly providing anesthesia for children requiring elective surgery with well controlled asthma but also for those requiring urgent surgery with poorly controlled or undiagnosed asthma. This second part of this two-part review details the medical and ventilatory management throughout the perioperative period in general but also includes the perioperative management of acute bronchospasm and asthma exacerbations in children with asthma. RECENT FINDINGS: Multiple observational trials assessing perioperative respiratory adverse events in healthy and asthmatic children provide the basis for identifying risk reduction strategies. Mainly, animal experiments and to a small extent clinical data have advanced our understanding of how anesthetic agents effect bronchial smooth muscle tone and blunt reflex bronchoconstriction. Asthma treatment outside anesthesia is well founded on a large body of evidence.Perioperative prevention strategies have increasingly been studied. However, evidence on the perioperative management, including mechanical ventilation strategies of asthmatic children, is still only fair, and further research is required. SUMMARY: To minimize the considerable risk of perioperative respiratory adverse events in asthmatic children, perioperative management should be based on two main pillars: the preoperative optimization of asthma treatment (please refer to the first part of this two-part review) and - the focus of this second part of this review - the optimization of anesthesia management in order to optimize lung function and minimize bronchial hyperreactivity in the perioperative period.

Incidence and risk factors for central venous access device failure in hospitalized adults: A multivariable analysis of 1892 catheters.

BACKGROUND: Central venous access devices (CVADs) allow intravenous therapy, haemodynamic monitoring and blood sampling but many fail before therapy completion. OBJECTIVE: To quantify CVAD failure and complications; and identify risk factors. DESIGNS, SETTINGS, AND PARTICIPANTS: Secondary analysis of multicentre randomised controlled trial including patients aged ≥16 years with a non-tunnelled CVAD (NTCVAD), peripherally-inserted central catheter (PICC) or tunnelled CVAD (TCVAD). Primary outcome was incidence of all-cause CVAD failure (central line-associated bloodstream infection [CLABSI], occlusion, accidental dislodgement, catheter fracture, thrombosis, pain). Secondary outcomes were CLABSI, occlusion and dislodgement. Cox regression was used to report time-to-event associations. RESULTS: In 1892 CVADs, all-cause failure occurred in 10.2% of devices: 49 NTCVADs (6.1%); 100 PICCs (13.2%); 44 TCVADs (13.4%). Failure rates for CLABSI, occlusion and dislodgement were 5.3%, 1.8%, and 1.7%, respectively. Independent CLABSI predictors were blood product administration through PICCs (hazard ratio (HR) 2.62, 95% confidence interval (CI) 1.24-5.55); and in TCVADs, one or two lumens, compared with three to four (HR 3.36, 95%CI 1.68-6.71), intravenous chemotherapy (HR 2.96, 95%CI 1.31-6.68), and diabetes (HR 3.25, 95%CI 1.40-7.57). Independent factors protective for CLABSI include antimicrobial NTCVADs (HR 0.23, 95%CI 0.08-0.63) and lipids in TCVADs (HR 0.32, 95%CI 0.14-0.72). NTCVADs inserted at another hospital (HR 7.06, 95%CI 1.48-33.7) and baseline infection in patients with PICCs (HR 2.72, 95%CI 1.08-6.83) were predictors for dislodgement. No independent occlusion predictors were found. Modifiable risk factors were identified for CVAD failure, which occurred for 1-in-10 catheters. Strict infection prevention measures and improved CVAD securement could reduce CLABSI and dislodgement risk.

Health concerns of intensive care survivors and research participation willingness: A multicentre survey.

Objective: To describe the relative importance of health concerns reported by survivors of critical illness treated in the intensive care unit (ICU), their estimate of time to achieve recovery, and their reported randomised clinical trial participation willingness. Design: A multicentre survey. Setting: Six Australian ICUs. Participants: Adult patients who had received mechanical ventilation, vasopressor support or renal replacement therapy for more than 24 h were likely to be discharged from ICU within 24 h. Interventions: Survey administration was verbal and occurred in the ICU. Main outcome measures: A numeric rating of eight ICU survivor-related health concerns developed with consumer input (disability requiring ongoing care, prolonged hospitalisation, repeated hospitalisation, impaired activity level, pain, low mood, inability to return home, and dying). Zero indicated no concern and ten extreme concern. Respondents were also asked to estimate their expected recovery time and their willingness to participate in a randomised clinical trial. Results: Of 584 eligible participants, 286 (49.0%) respondents had a mean age of 62.3 years (standard deviation (SD) 14.8) and 178 (62.2%) were male. The median ICU length of stay at the time of survey was 4 days (interquartile range (IQR) 3-7). Respondents reported high levels of concern for all health outcomes with the highest median scores being for survival with severe disability and requirement for ongoing care scoring 8 (IQR 3-10), and never being able to return home needing assisted living or a nursing home scoring 8 (IQR 1-10). The median expected recovery time was 23 days (IQR 10-33). Higher concerns were associated with an increased likelihood of trial participation willingness. Conclusion: Survivors reported high and varied health concerns of which severe disability requiring care and inability to return home were the highest. Respondents anticipated a relatively short recovery.

Risk factors for arterial catheter failure and complications during critical care hospitalisation: a secondary analysis of a multisite, randomised trial.

OBJECTIVES: Arterial catheters (ACs) are critical for haemodynamic monitoring and blood sampling but are prone to complications. We investigated the incidence and risk factors of AC failure. METHODS: Secondary analysis of a multi-centre randomised controlled trial (ACTRN 12610000505000). Analysis included a subset of adult intensive care unit patients with an AC. The primary outcome was all-cause device failure. Secondary outcomes were catheter associated bloodstream infection (CABSI), suspected CABSI, occlusion, thrombosis, accidental removal, pain, and line fracture. Risk factors associated with AC failure were investigated using Cox proportional hazards and competing-risk models. RESULTS: Of 664 patients, 173 (26%) experienced AC failure (incidence rate [IR] 37/1000 catheter days). Suspected CABSI was the most common failure type (11%; IR 15.3/1000 catheter days), followed by occlusion (8%; IR 11.9/1,000 catheter days), and accidental removal (4%; IR 5.5/1000 catheter days). CABSI occurred in 16 (2%) patients. All-cause failure and occlusion were reduced with ultrasound-assisted insertion (failure: adjusted hazard ratio [HR] 0.43, 95% CI 0.25, 0.76; occlusion: sub-HR 0.11, 95% CI 0.03, 0.43). Increased age was associated with less AC failure (60-74 years HR 0.63, 95% CI 0.44 to 0.89; 75 + years HR 0.36, 95% CI 0.20, 0.64; referent 15-59 years). Females experienced more occlusion (adjusted sub-HR 2.53, 95% CI 1.49, 4.29), while patients with diabetes had less (SHR 0.15, 95% CI 0.04, 0.63). Suspected CABSI was associated with an abnormal insertion site appearance (SHR 2.71, 95% CI 1.48, 4.99). CONCLUSIONS: AC failure is common with ultrasound-guided insertion associated with lower failure rates. Trial registration Australian New Zealand Clinical Trial Registry (ACTRN 12610000505000); date registered: 18 June 2010.

Matching positive end-expiratory pressure to intra-abdominal pressure prevents end-expiratory lung volume decline in a pig model of intra-abdominal hypertension.

OBJECTIVE: Intra-abdominal hypertension is common in critically ill patients and is associated with increased morbidity and mortality. In a previous experimental study, positive end-expiratory pressures of up to 15 cm H2O did not prevent end-expiratory lung volume decline caused by intra-abdominal hypertension. Therefore, we examined the effect of matching positive end-expiratory pressure to the intra-abdominal pressure on cardio-respiratory parameters. DESIGN: Experimental pig model of intra-abdominal hypertension. SETTING: Large animal facility, University of Western Australia. SUBJECTS: Nine anesthetized, nonparalyzed, and ventilated pigs (48 ± 7 kg). INTERVENTIONS: Four levels of intra-abdominal pressure (baseline, 12, 18, and 22 mm Hg) were generated in a randomized order by inflating an intra-abdominal balloon. At each level of intra-abdominal pressure, three levels of positive end-expiratory pressure were randomly applied with varying degrees of matching the corresponding intra-abdominal pressure: baseline positive end-expiratory pressure (= 5 cm H2O), moderate positive end-expiratory pressure (= half intra-abdominal pressure in cm H2O + 5 cm H2O), and high positive end-expiratory pressure (= intra-abdominal pressure in cm H2O). MEASUREMENTS: We measured end-expiratory lung volume, arterial oxygen levels, respiratory mechanics, and cardiac output 5 mins after each new intra-abdominal pressure and positive end-expiratory pressure setting. MAIN RESULTS: Intra-abdominal hypertension decreased end-expiratory lung volume and PaO2 (-49% [p < .001] and -8% [p < .05], respectively, at 22 mm Hg intra-abdominal pressure compared with baseline intra-abdominal pressure) but did not change cardiac output (p = .5). At each level of intra-abdominal pressure, moderate positive end-expiratory pressure increased end-expiratory lung volume (+119% [p < .001] at 22 mm Hg intra-abdominal pressure compared with 5 cm H2O positive end-expiratory pressure) while minimally decreasing cardiac output (-8%, p < .05). High positive end-expiratory pressure further increased end-expiratory lung volume (+233% [p < .001] at 22 mm Hg intra-abdominal pressure compared with 5 cm H2O positive end-expiratory pressure) but led to a greater decrease in cardiac output (-26%, p < .05). Neither moderate nor high positive end-expiratory pressure improved PaO2 (p = .7). Intra-abdominal hypertension decreased end-expiratory transpulmonary pressure but did not alter end-inspiratory transpulmonary pressure. Intra-abdominal hypertension decreased total respiratory compliance through a decrease in chest wall compliance. Positive end-expiratory pressure decreased the respiratory compliance by reducing lung compliance. CONCLUSIONS: In a pig model of intra-abdominal hypertension, positive end-expiratory pressure matched to intra-abdominal pressure led to a preservation of end-expiratory lung volume, but did not improve arterial oxygen tension and caused a reduction in cardiac output. Therefore, we do not recommend routine application of positive end-expiratory pressure matched to intra-abdominal pressure to prevent intra-abdominal pressure-induced end-expiratory lung volume decline in healthy lungs.

Matching positive end-expiratory pressure to intra-abdominal pressure improves oxygenation in a porcine sick lung model of intra-abdominal hypertension.

INTRODUCTION: Intra-abdominal hypertension (IAH) causes atelectasis, reduces lung volumes and increases respiratory system elastance. Positive end-expiratory pressure (PEEP) in the setting of IAH and healthy lungs improves lung volumes but not oxygenation. However, critically ill patients with IAH often suffer from acute lung injury (ALI). This study, therefore, examined the respiratory and cardiac effects of positive end-expiratory pressure in an animal model of IAH, with sick lungs. METHODS: Nine pigs were anesthetized and ventilated (48 +/- 6 kg). Lung injury was induced with oleic acid. Three levels of intra-abdominal pressure (baseline, 18, and 22 mmHg) were randomly generated. At each level of intra-abdominal pressure, three levels of PEEP were randomly applied: baseline (5 cmH2O), moderate (0.5 × intra-abdominal pressure), and high (1.0 × intra-abdominal pressure). We measured end-expiratory lung volumes, arterial oxygen levels, respiratory mechanics, and cardiac output 10 minutes after each new IAP and PEEP setting. RESULTS: At baseline PEEP, IAH (22 mmHg) decreased oxygen levels (-55%, P <0.001) and end-expiratory lung volumes (-45%, P = 0.007). At IAP of 22 mmHg, moderate and high PEEP increased oxygen levels (+60%, P = 0.04 and +162%, P <0.001) and end-expiratory lung volume (+44%, P = 0.02 and +279%, P <0.001) and high PEEP reduced cardiac output (-30%, P = 0.04). Shunt and dead-space fraction inversely correlated with oxygen levels and end-expiratory lung volumes. In the presence of IAH, lung, chest wall and respiratory system elastance increased. Subsequently, PEEP decreased respiratory system elastance by decreasing chest wall elastance. CONCLUSIONS: In a porcine sick lung model of IAH, PEEP matched to intra-abdominal pressure led to increased lung volumes and oxygenation and decreased chest wall elastance shunt and dead-space fraction. High PEEP decreased cardiac output. The study shows that lung injury influences the effects of IAH and PEEP on oxygenation and respiratory mechanics. Our findings support the application of PEEP in the setting of acute lung injury and IAH.

Elastic properties of the central airways in obstructive lung diseases measured using anatomical optical coherence tomography.

RATIONALE: Our understanding of how airway remodeling affects regional airway elastic properties is limited due to technical difficulties in quantitatively measuring dynamic, in vivo airway dimensions. Such knowledge could help elucidate mechanisms of excessive airway narrowing. OBJECTIVES: To use anatomical optical coherence tomography (aOCT) to compare central airway elastic properties in control subjects and those with obstructive lung diseases. METHODS: After bronchodilation, airway lumen area (Ai) was measured using aOCT during bronchoscopy in control subjects (n = 10) and those with asthma (n = 16), chronic obstructive pulmonary disease (COPD) (n = 9), and bronchiectasis (n = 8). Ai was measured in each of generations 0 to 5 while airway pressure was increased from -10 to 20 cm H(2)O. Airway compliance (Caw) and specific compliance (sCaw) were derived from the transpulmonary pressure (Pl) versus Ai curves. MEASUREMENTS AND MAIN RESULTS: Caw decreased progressively as airway generation increased, but sCaw did not differ appreciably across the generations. In subjects with asthma and bronchiectasis, Caw and sCaw were similar to control subjects and the Pl-Ai curves were left-shifted. No significant differences were observed between control and COPD groups. CONCLUSIONS: Proximal airway elastic properties are altered in obstructive lung diseases. Although central airway compliance does not differ from control subjects in asthma, bronchiectasis, or COPD, Ai is lower in asthma and the Pl-Ai relationship is left-shifted in both asthma and bronchiectasis, suggesting that airways are maximally distended at lower inflating pressures. Such changes reflect alteration in the balance between airway wall distensibility and radial traction exerted on airways by surrounding lung parenchyma favoring airway narrowing. Clinical trial registered with Australian New Zealand Clinical Trials Registry (ACTRN12607000624482).

Impact of intraabdominal hypertension on kidney failure in critically ill patients: A post-hoc database analysis.

PURPOSE: To assess whether intraabdominal hypertension (IAH) may influence kidney failure as well as mortality. METHODS: This post-hoc analysis of two databases (IROI and iSOFA study) tested the independent association between IAH and kidney failure. Mortality was assessed using four prespecified groups (IAH present, kidney failure present, IAH and kidney failure present and no IAH or kidney failure present). RESULTS: Of 825 critically ill patients, 302 (36.6%) developed kidney failure and 192 (23.7%) died during the first 90 days. Only 'Cumulative days with IAH grade II or more' was significantly associated with kidney failure (OR 1.29 (1.08-1.55), p = 0.003) while 'cumulative days with IAH grade I or more' (p = 0.135) or highest daily IAP (p = 0.062) was not. IAH combined with kidney failure was independently associated with 90-day mortality (OR 2.20 (1.20-4.05), p = 0.011), which was confirmed for higher grades of IAH (grade II or more) alone (OR 2.14 (1.07-4.30), p = 0.032) and combined with kidney failure (OR 3.25 (1.72-6.12), p < 0.001). CONCLUSIONS: This study suggest that duration as well as higher grades of IAH are associated with kidney failure and may increase mortality.

The effect of non-invasive ventilation on intra-abdominal pressure.

BACKGROUND: Non-invasive ventilation is a well-established treatment modality in patients with respiratory failure of different aetiologies. A previous case report described how non-invasive ventilation caused gastric distension and intra-abdominal hypertension with subsequent cardio-respiratory arrest and clinical recovery following resuscitative efforts including gastric decompression with a nasogastric tube. METHODS: The aim of this prospective multicentre observational study was to assess the effect of non-invasive ventilation on intra-abdominal pressure. Following informed consent, intra-abdominal pressure and PaCO2 were measured before and after the application of non-invasive ventilation for up to three days in critically ill patients requiring non-invasive ventilation. RESULTS: Thirty-five patients were enrolled; mean (±SD) age of 67.8 (±12.5) years, median (interquartile range) body mass index of 27.9 (24.5-30.0) kg m-2, Acute Physiology and Chronic Health Evaluation II score of 15.8 (±6.4). On admission and after 24 hours of non-invasive ventilation, intra-abdominal pressure was 11.0 (7.5-15.0) mm Hg and 11.0 (8.5-14.5) mm Hg (P = 0.82) and PaCO2 was 44.4 (±11.4) mm Hg and 51.3 (±14.3) mm Hg (P = 0.19), respectively. CONCLUSIONS: The application of non-invasive ventilation was not associated with an increase in intra-abdominal pressure over 72 hours in this small observational study. Thus, it appears that intra-abdominal pressure does not frequently increase when applying non-invasive ventilation in critically ill patients with respiratory failure.

Prophylactic melatonin for delirium in intensive care (Pro-MEDIC): a randomized controlled trial.

PURPOSE: Delirium is common in the critically ill, highly distressing to patients and families and associated with increased morbidity and mortality. Results of studies on preventative use of melatonin in various patient groups have produced mixed results. The aim of this study was to determine whether administration of melatonin decreases the prevalence of delirium in critically ill patients. METHODS: Multicentre, randomized, placebo-controlled, double-blind trial across 12 Australian ICUs recruiting patients from July 2016 to September 2019. Patients of at least 18 years requiring ICU admission with an expected length of stay (LOS) greater than 72 h; enrolled within 48 h of ICU admission. Indistinguishable liquid melatonin (4 mg; n = 419) or placebo (n = 422) was administered enterally at 21:00 h for 14 consecutive nights or until ICU discharge. The primary outcome was the proportion of delirium-free assessments, as a marker of delirium prevalence, within 14 days or before ICU discharge. Delirium was assessed twice daily using the Confusion Assessment Method for ICU (CAM-ICU) score. Secondary outcomes included sleep quality and quantity, hospital and ICU LOS, and hospital and 90-day mortality. RESULTS: A total of 847 patients were randomized into the study with 841 included in data analysis. Baseline characteristics of the participants were similar. There was no significant difference in the average proportion of delirium-free assessments per patient between the melatonin and placebo groups (79.2 vs 80% respectively, p = 0.547). There was no significant difference in any secondary outcomes including ICU LOS (median: 5 vs 5 days, p = 0.135), hospital LOS (median: 14 vs 12 days, p = 0816), mortality at any time point including at 90 days (15.5 vs 15.6% p = 0.948), nor in the quantity or quality of sleep. There were no serious adverse events reported in either group. CONCLUSION: Enteral melatonin initiated within 48 h of ICU admission did not reduce the prevalence of delirium compared to placebo. These findings do not support the routine early use of melatonin in the critically ill.

More than half of front-line healthcare workers unknowingly used an N95/P2 mask without adequate airborne protection: An audit in a tertiary institution.

Front-line staff routinely exposed to aerosol-generating procedures are at a particularly high risk of transmission of severe acute respiratory syndrome coronavirus 2. We aimed to assess the adequacy of respiratory protection provided by available N95/P2 masks to staff routinely exposed to aerosol-generating procedures. We performed a prospective audit of fit-testing results. A convenience sample of staff from the Department of Anaesthesia and Pain Medicine, who opted to undergo qualitative and/or quantitative fit-testing of N95/P2 masks was included. Fit-testing was performed following standard guidelines including a fit-check. We recorded the type and size of mask, pass or failure and duration of fit-testing. Staff completed a short questionnaire on previous N95/P2 mask training regarding confidence and knowledge gained through fit-testing. The first fit-pass rate using routinely available N95/P2 masks at this institution was only 47%. Fit-pass rates increased by testing different types and sizes of masks. Confidence 'that the available mask will provide adequate fit' was higher after fit-testing compared with before fit-testing; (median, interquartile range) five-point Likert-scale (4.0 (4.0-5.0) versus 3.0 (2.0-4.0); P<0.001). This audit highlights that without fit-testing over 50% of healthcare workers were using an N95/P2 mask that provided insufficient airborne protection. This high unnoticed prevalence of unfit masks among healthcare workers can create a potentially hazardous false sense of security. However, fit-testing of different masks not only improved airborne protection provided to healthcare workers but also increased their confidence around mask protection.

Computed tomographic assessment of lung aeration at different positive end-expiratory pressures in a porcine model of intra-abdominal hypertension and lung injury.

BACKGROUND: Intra-abdominal hypertension (IAH) is common in critically ill patients and is associated with increased morbidity and mortality. High positive end-expiratory pressures (PEEP) can reverse lung volume and oxygenation decline caused by IAH, but its impact on alveolar overdistension is less clear. We aimed to find a PEEP range that would be high enough to reduce atelectasis, while low enough to minimize alveolar overdistention in the presence of IAH and lung injury. METHODS: Five anesthetized pigs received standardized anesthesia and mechanical ventilation. Peritoneal insufflation of air was used to generate intra-abdominal pressure of 27 cmH2O. Lung injury was created by intravenous oleic acid. PEEP levels of 5, 12, 17, 22, and 27 cmH2O were applied. We performed computed tomography and measured arterial oxygen levels, respiratory mechanics, and cardiac output 5 min after each new PEEP level. The proportion of overdistended, normally aerated, poorly aerated, and non-aerated atelectatic lung tissue was calculated based on Hounsfield units. RESULTS: PEEP decreased the proportion of poorly aerated and atelectatic lung, while increasing normally aerated lung. Overdistension increased with each incremental increase in applied PEEP. "Best PEEP" (respiratory mechanics or oxygenation) was higher than the "optimal CT inflation PEEP range" (difference between lower inflection points of atelectatic and overdistended lung) in healthy and injured lungs. CONCLUSIONS: Our findings in a large animal model suggest that titrating a PEEP to respiratory mechanics or oxygenation in the presence of IAH is associated with increased alveolar overdistension.