The Incidence of Pulmonary Embolism in Hospitalized Non-ICU Patients with COVID-19 during the First Wave: A Multicenter Retrospective Cohort Study in the Netherlands

INTRODUCTION

During the first COVID-19 outbreak in 2020 in the Netherlands, the incidence of pulmonary embolism (PE) appeared to be high in COVID-19 patients admitted to the intensive care unit (ICU). This study was performed to evaluate the incidence of PE during hospital stay in COVID-19 patients not admitted to the ICU.

METHODS

Data were retrospectively collected from 8 hospitals in the Netherlands. Patients admitted between February 27, 2020, and July 31, 2020, were included. Data extracted comprised clinical characteristics, medication use, first onset of COVID-19-related symptoms, admission date due to COVID-19, and date of PE diagnosis. Only polymerase chain reaction (PCR)-positive patients were included. All PEs were diagnosed with computed tomography pulmonary angiography (CTPA).

RESULTS

Data from 1,852 patients who were admitted to the hospital ward were collected. Forty patients (2.2%) were diagnosed with PE within 28 days following hospital admission. The median time to PE since admission was 4.5 days (IQR 0.0-9.0). In all 40 patients, PE was diagnosed within the first 2 weeks after hospital admission and for 22 (55%) patients within 2 weeks after onset of symptoms. Patient characteristics, pre-existing comorbidities, anticoagulant use, and laboratory parameters at admission were not related to the development of PE.

CONCLUSION

In this retrospective multicenter cohort study of 1,852 COVID-19 patients only admitted to the non-ICU wards, the incidence of CTPA-confirmed PE was 2.2% during the first 4 weeks after onset of symptoms and occurred exclusively within 2 weeks after hospital admission.

Predictors for Long COVID and Differences in Long COVID Symptoms, Findings on Chest Imaging and Pulmonary Function between Hospitalized COVID-19 Patients with versus without Intensive Care Unit Admission

INTRODUCTION

Many COVID-19 survivors suffer from persisting sequelae after acute disease. This is referred to as long COVID. The objectives of this study were to assess factors associated with long COVID and to analyze differences in persistent symptoms, findings on chest imaging, and pulmonary function between intensive care unit (ICU) and non-ICU hospitalized patients.

METHODS

We conducted a retrospective study including patients hospitalized with COVID-19. Patients were stratified into ICU patients and non-ICU patients. We analyzed the outcomes of patients who were in clinical follow-up 6 months after discharge with persistent symptoms, radiological and/or functional abnormalities. Logistic regression was used to examine the association between long COVID and patient characteristics.

RESULTS

A total of 549 patients were included. Eighty-one ICU patients (66%) and 146 (34%) non-ICU patients had persistent symptoms or abnormalities on chest imaging or lung function test minimally 6 months after discharge. Significantly more ICU patients had residual fibrotic abnormalities on chest CT and functional impairment. Female gender, myocardial infarction, OSAS, low PCO2 at admission, and longer hospital stay were associated with a higher risk of developing long COVID. Diabetes and treatment with tocilizumab were associated with a lower risk of developing long COVID.

CONCLUSION

Of the patients hospitalized for COVID-19, 34-66% suffered from persistent symptoms, residual abnormalities on chest imaging, or reduced lung function at around 6 months after discharge. While persistent sequelae were more frequent in ICU patients, admission to the ICU was not found to be an independent risk factor for developing long COVID.

Does atrial fibrillation affect prognosis in hospitalised COVID-19 patients? A multicentre historical cohort study in the Netherlands

OBJECTIVES

The aim of this multicentre COVID-PREDICT study (a nationwide observational cohort study that aims to better understand clinical course of COVID-19 and to predict which COVID-19 patients should receive which treatment and which type of care) was to determine the association between atrial fibrillation (AF) and mortality, intensive care unit (ICU) admission, complications and discharge destination in hospitalised COVID-19 patients.

SETTING

Data from a historical cohort study in eight hospitals (both academic and non-academic) in the Netherlands between January 2020 and July 2021 were used in this study.

PARTICIPANTS

3064 hospitalised COVID-19 patients >18 years old.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was the incidence of new-onset AF during hospitalisation. Secondary outcomes were the association between new-onset AF (vs prevalent or non-AF) and mortality, ICU admissions, complications and discharge destination, performed by univariable and multivariable logistic regression analyses.

RESULTS

Of the 3064 included patients (60.6% men, median age: 65 years, IQR 55-75 years), 72 (2.3%) patients had prevalent AF and 164 (5.4%) patients developed new-onset AF during hospitalisation. Compared with patients without AF, patients with new-onset AF had a higher incidence of death (adjusted OR (aOR) 1.71, 95% CI 1.17 to 2.59) an ICU admission (aOR 5.45, 95% CI 3.90 to 7.61). Mortality was non-significantly different between patients with prevalent AF and those with new-onset AF (aOR 0.97, 95% CI 0.53 to 1.76). However, new-onset AF was associated with a higher incidence of ICU admission and complications compared with prevalent AF (OR 6.34, 95% CI 2.95 to 13.63, OR 3.04, 95% CI 1.67 to 5.55, respectively).

CONCLUSION

New-onset AF was associated with an increased incidence of death, ICU admission, complications and a lower chance to be discharged home. These effects were far less pronounced in patients with prevalent AF. Therefore, new-onset AF seems to represent a marker of disease severity, rather than a cause of adverse outcomes.

Optimal Dosing and Timing of High-Dose Corticosteroid Therapy in Hospitalized Patients With COVID-19: Study Protocol for a Retrospective Observational Multicenter Study (SELECT)

BACKGROUND

In hospitalized patients with COVID-19, the dosing and timing of corticosteroids vary widely. Low-dose dexamethasone therapy reduces mortality in patients requiring respiratory support, but it remains unclear how to treat patients when this therapy fails. In critically ill patients, high-dose corticosteroids are often administered as salvage late in the disease course, whereas earlier administration may be more beneficial in preventing disease progression. Previous research has revealed that increased levels of various biomarkers are associated with mortality, and whole blood transcriptome sequencing has the ability to identify host factors predisposing to critical illness in patients with COVID-19.

OBJECTIVE

Our goal is to determine the most optimal dosing and timing of corticosteroid therapy and to provide a basis for personalized corticosteroid treatment regimens to reduce morbidity and mortality in hospitalized patients with COVID-19.

METHODS

This is a retrospective, observational, multicenter study that includes adult patients who were hospitalized due to COVID-19 in the Netherlands. We will use the differences in therapeutic strategies between hospitals (per protocol high-dose corticosteroids or not) over time to determine whether high-dose corticosteroids have an effect on the following outcome measures: mechanical ventilation or high-flow nasal cannula therapy, in-hospital mortality, and 28-day survival. We will also explore biomarker profiles in serum and bronchoalveolar lavage fluid and use whole blood transcriptome analysis to determine factors that influence the relationship between high-dose corticosteroids and outcome. Existing databases that contain routinely collected electronic data during ward and intensive care admissions, as well as existing biobanks, will be used. We will apply longitudinal modeling appropriate for each data structure to answer the research questions at hand.

RESULTS

As of April 2023, data have been collected for a total of 1500 patients, with data collection anticipated to be completed by December 2023. We expect the first results to be available in early 2024.

CONCLUSIONS

This study protocol presents a strategy to investigate the effect of high-dose corticosteroids throughout the entire clinical course of hospitalized patients with COVID-19, from hospital admission to the ward or intensive care unit until hospital discharge. Moreover, our exploration of biomarker and gene expression profiles for targeted corticosteroid therapy represents a first step towards personalized COVID-19 corticosteroid treatment.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05403359; https://clinicaltrials.gov/ct2/show/NCT05403359.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/48183.

Overweight and obesity are not associated with worse clinical outcomes in COVID-19 patients treated with fixed-dose 6 mg dexamethasone

Objective

A fixed 6 mg dexamethasone dose for 10 days is the standard treatment for all hospitalised COVID-19 patients who require supplemental oxygen. Yet, the pharmacokinetic properties of dexamethasone can lead to diminishing systemic dexamethasone exposure with increasing body mass index (BMI). The present study examines whether this translates to overweight and obesity being associated with worse clinical outcomes, defined as ICU admission or in hospital death, in COVID-19 patients treated with fixed-dose dexamethasone.

Methods

We conducted a single centre retrospective cohort study in COVID-19 patients who were admitted to a non-ICU ward and were treated with dexamethasone (6 mg once daily for a maximum of ten days) between June 2020 and January 2021. Univariable and multivariable logistic regression analyses were conducted to assess the association between BMI-categories and an unfavourable clinical course (ICU admission and/or in hospital death). Analyses were adjusted for age, comorbidities, inflammatory status, and oxygen requirement at admission. For reference, similar analyses were repeated in a cohort of patients hospitalised before dexamethasone was introduced (March 2020 through May 2020).

Results

In patients treated with dexamethasone (n = 385) an unfavourable clinical course was most prevalent in patients with normal weight (BMI < 25) compared to patients with overweight (BMI 25–30) and patients with obesity (BMI ≥ 30) with percentages of 33, 26 and 21% respectively. In multivariable analyses, there was no association between BMI-category and an unfavourable clinical course (respectively with aORs of 0.81 (0.43–1.53) and 0.61 (0.30–1.27) with normal weight as reference). In the reference cohort (n = 249) the opposite was observed with an unfavourable clinical course being most prevalent in patients with overweight (39% vs 28%; aOR 2.17 (0.99–4.76)). In both cohorts, CRP level at admission was higher and lymphocyte count was lower in patients with normal weight compared to patients with obesity.

Conclusions

Overweight and obesity are not associated with an unfavourable clinical course in COVID-19 patients admitted to a non-ICU ward and treated with 6 mg dexamethasone once daily.

Treatment with a DPP-4 inhibitor at time of hospital admission for COVID-19 is not associated with improved clinical outcomes: data from the COVID-PREDICT cohort study in The Netherlands

Purpose

Inhibition of dipeptidyl peptidase (DPP-)4 could reduce coronavirus disease 2019 (COVID-19) severity by reducing inflammation and enhancing tissue repair beyond glucose lowering. We aimed to assess this in a prospective cohort study.

Methods

We studied in 565 patients with type 2 diabetes in the CovidPredict Clinical Course Cohort whether use of a DPP-4 inhibitor prior to hospital admission due to COVID-19 was associated with improved clinical outcomes. Using crude analyses and propensity score matching (on age, sex and BMI), 28 patients using a DPP-4 inhibitor were identified and compared to non-users.

Results

No differences were found in the primary outcome mortality (matched-analysis = odds-ratio: 0,94 [95% confidence interval: 0,69 – 1,28], p-value: 0,689) or any of the secondary outcomes (ICU admission, invasive ventilation, thrombotic events or infectious complications). Additional analyses comparing users of DPP-4 inhibitors with subgroups of non-users (subgroup 1: users of metformin and sulphonylurea; subgroup 2: users of any insulin combination), allowing to correct for diabetes severity, did not yield different results.

Conclusions

We conclude that outpatient use of a DPP-4 inhibitor does not affect the clinical outcomes of patients with type 2 diabetes who are hospitalized because of COVID-19 infection.

Overweight and Obesity Are Associated With Acute Kidney Injury and Acute Respiratory Distress Syndrome, but Not With Increased Mortality in Hospitalized COVID-19 Patients: A Retrospective Cohort Study

OBJECTIVE

To evaluate the association between overweight and obesity on the clinical course and outcomes in patients hospitalized with COVID-19.

DESIGN

Retrospective, observational cohort study.

METHODS

We performed a multicenter, retrospective, observational cohort study of hospitalized COVID-19 patients to evaluate the associations between overweight and obesity on the clinical course and outcomes.

RESULTS

Out of 1634 hospitalized COVID-19 patients, 473 (28.9%) had normal weight, 669 (40.9%) were overweight, and 492 (30.1%) were obese. Patients who were overweight or had obesity were younger, and there were more women in the obese group. Normal-weight patients more often had pre-existing conditions such as malignancy, or were organ recipients. During admission, patients who were overweight or had obesity had an increased probability of acute respiratory distress syndrome [OR 1.70 (1.26-2.30) and 1.40 (1.01-1.96)], respectively and acute kidney failure [OR 2.29 (1.28-3.76) and 1.92 (1.06-3.48)], respectively. Length of hospital stay was similar between groups. The overall in-hospital mortality rate was 27.7%, and multivariate logistic regression analyses showed that overweight and obesity were not associated with increased mortality compared to normal-weight patients.

CONCLUSION

In this study, overweight and obesity were associated with acute respiratory distress syndrome and acute kidney injury, but not with in-hospital mortality nor length of hospital stay.

Outcomes of persons with coronavirus disease 2019 in hospitals with and without standard treatment with (hydroxy)chloroquine

Objective

To compare survival of individuals with coronavirus disease 2019 (COVID-19) treated in hospitals that either did or did not routinely treat patients with hydroxychloroquine or chloroquine.

Methods

We analysed data of COVID-19 patients treated in nine hospitals in the Netherlands. Inclusion dates ranged from 27 February to 15 May 2020, when the Dutch national guidelines no longer supported the use of (hydroxy)chloroquine. Seven hospitals routinely treated patients with (hydroxy)chloroquine, two hospitals did not. Primary outcome was 21-day all-cause mortality. We performed a survival analysis using log-rank test and Cox regression with adjustment for age, sex and covariates based on premorbid health, disease severity and the use of steroids for adult respiratory distress syndrome, including dexamethasone.

Results

Among 1949 individuals, 21-day mortality was 21.5% in 1596 patients treated in hospitals that routinely prescribed (hydroxy)chloroquine, and 15.0% in 353 patients treated in hospitals that did not. In the adjusted Cox regression models this difference disappeared, with an adjusted hazard ratio of 1.09 (95% CI 0.81–1.47). When stratified by treatment actually received in individual patients, the use of (hydroxy)chloroquine was associated with an increased 21-day mortality (HR 1.58; 95% CI 1.24–2.02) in the full model.

Conclusions

After adjustment for confounders, mortality was not significantly different in hospitals that routinely treated patients with (hydroxy)chloroquine compared with hospitals that did not. We compared outcomes of hospital strategies rather than outcomes of individual patients to reduce the chance of indication bias. This study adds evidence against the use of (hydroxy)chloroquine in hospitalised patients with COVID-19.

RELAx - REstricted versus Liberal positive end-expiratory pressure in patients without ARDS: protocol for a randomized controlled trial

BACKGROUND

Evidence for benefit of high positive end-expiratory pressure (PEEP) is largely lacking for invasively ventilated, critically ill patients with uninjured lungs. We hypothesize that ventilation with low PEEP is noninferior to ventilation with high PEEP with regard to the number of ventilator-free days and being alive at day 28 in this population.  METHODS/DESIGN: The "REstricted versus Liberal positive end-expiratory pressure in patients without ARDS" trial (RELAx) is a national, multicenter, randomized controlled, noninferiority trial in adult intensive care unit (ICU) patients with uninjured lungs who are expected not to be extubated within 24 h. RELAx will run in 13 ICUs in the Netherlands to enroll 980 patients under invasive ventilation. In all patients, low tidal volumes are used. Patients assigned to ventilation with low PEEP will receive the lowest possible PEEP between 0 and 5 cm H2O, while patients assigned to ventilation with high PEEP will receive PEEP of 8 cm H2O. The primary endpoint is the number of ventilator-free days and being alive at day 28, a composite endpoint for liberation from the ventilator and mortality until day 28, with a noninferiority margin for a difference between groups of 0.5 days. Secondary endpoints are length of stay (LOS), mortality, and occurrence of pulmonary complications, including severe hypoxemia, major atelectasis, need for rescue therapies, pneumonia, pneumothorax, and development of acute respiratory distress syndrome (ARDS). Hemodynamic support and sedation needs will be collected and compared.

DISCUSSION

RELAx will be the first sufficiently sized randomized controlled trial in invasively ventilated, critically ill patients with uninjured lungs using a clinically relevant and objective endpoint to determine whether invasive, low-tidal-volume ventilation with low PEEP is noninferior to ventilation with high PEEP.

TRIAL REGISTRATION

ClinicalTrials.gov , ID: NCT03167580 . Registered on 23 May 2017.

Effect of On-Demand vs Routine Nebulization of Acetylcysteine With Salbutamol on Ventilator-Free Days in Intensive Care Unit Patients Receiving Invasive Ventilation: A Randomized Clinical Trial

IMPORTANCE

It remains uncertain whether nebulization of mucolytics with bronchodilators should be applied for clinical indication or preventively in intensive care unit (ICU) patients receiving invasive ventilation.

OBJECTIVE

To determine if a strategy that uses nebulization for clinical indication (on-demand) is noninferior to one that uses preventive (routine) nebulization.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial enrolling adult patients expected to need invasive ventilation for more than 24 hours at 7 ICUs in the Netherlands.

INTERVENTIONS

On-demand nebulization of acetylcysteine or salbutamol (based on strict clinical indications, n = 471) or routine nebulization of acetylcysteine with salbutamol (every 6 hours until end of invasive ventilation, n = 473).

MAIN OUTCOMES AND MEASURES

The primary outcome was the number of ventilator-free days at day 28, with a noninferiority margin for a difference between groups of -0.5 days. Secondary outcomes included length of stay, mortality rates, occurrence of pulmonary complications, and adverse events.

RESULTS

Nine hundred twenty-two patients (34% women; median age, 66 (interquartile range [IQR], 54-75 years) were enrolled and completed follow-up. At 28 days, patients in the on-demand group had a median 21 (IQR, 0-26) ventilator-free days, and patients in the routine group had a median 20 (IQR, 0-26) ventilator-free days (1-sided 95% CI, -0.00003 to ∞). There was no significant difference in length of stay or mortality, or in the proportion of patients developing pulmonary complications, between the 2 groups. Adverse events (13.8% vs 29.3%; difference, -15.5% [95% CI, -20.7% to -10.3%]; P < .001) were more frequent with routine nebulization and mainly related to tachyarrhythmia (12.5% vs 25.9%; difference, -13.4% [95% CI, -18.4% to -8.4%]; P < .001) and agitation (0.2% vs 4.3%; difference, -4.1% [95% CI, -5.9% to -2.2%]; P < .001).

CONCLUSIONS AND RELEVANCE

Among ICU patients receiving invasive ventilation who were expected to not be extubated within 24 hours, on-demand compared with routine nebulization of acetylcysteine with salbutamol did not result in an inferior number of ventilator-free days. On-demand nebulization may be a reasonable alternative to routine nebulization.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT02159196.

Preventive nebulization of mucolytic agents and bronchodilating drugs in invasively ventilated intensive care unit patients (NEBULAE): study protocol for a randomized controlled trial

Background

Preventive nebulization of mucolytic agents and bronchodilating drugs is a strategy aimed at the prevention of sputum plugging, and therefore atelectasis and pneumonia, in intubated and ventilated intensive care unit (ICU) patients. The present trial aims to compare a strategy using the preventive nebulization of acetylcysteine and salbutamol with nebulization on indication in intubated and ventilated ICU patients.

Methods/Design

The preventive nebulization of mucolytic agents and bronchodilating drugs in invasively ventilated intensive care unit patients (NEBULAE) trial is a national multicenter open-label, two-armed, randomized controlled non-inferiority trial in the Netherlands. Nine hundred and fifty intubated and ventilated ICU patients with an anticipated duration of invasive ventilation of more than 24 hours will be randomly assigned to receive either a strategy consisting of preventive nebulization of acetylcysteine and salbutamol or a strategy consisting of nebulization of acetylcysteine and/or salbutamol on indication. The primary endpoint is the number of ventilator-free days and surviving on day 28. Secondary endpoints include ICU and hospital length of stay, ICU and hospital mortality, the occurrence of predefined pulmonary complications (acute respiratory distress syndrome, pneumonia, large atelectasis and pneumothorax), and the occurrence of predefined side effects of the intervention. Related healthcare costs will be estimated in a cost-benefit and budget-impact analysis.

Discussion

The NEBULAE trial is the first randomized controlled trial powered to investigate whether preventive nebulization of acetylcysteine and salbutamol shortens the duration of ventilation in critically ill patients.

Trial registration

NCT02159196, registered on 6 June 2014.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-015-0865-0) contains supplementary material, which is available to authorized users.

Intensive insulin therapy in intensive care: an example of the struggle to implement evidence-based medicine

Schultz and colleagues discuss the factors hindering implementation of intensive insulin therapy.

Evaluation of short-term consequences of hypoglycemia in an intensive care unit

BACKGROUND

Introduction of strict glycemic control has increased the risk for hypoglycemia in the intensive care unit. Little is known about the consequences of hypoglycemia in this setting. We examined short-term consequences (seizures, coma, and death) of hypoglycemia in the intensive care unit.

PATIENTS AND METHODS

All occurrences of hypoglycemia (glucose of <45 mg/dL) in our intensive care unit between September 1, 2002, and September 1, 2004, were identified. Patients with hypoglycemia (n = 156) were matched for time to hypoglycemia with control patients drawn from the at-risk population (nested case control method). Seizures observed within 8 hrs after hypoglycemia were scored. Discharge summaries for cases and controls were reviewed for occurrence of possible hypoglycemia-associated coma and death. A hazard ratio for in-hospital death was calculated with Cox regression analysis.

RESULTS

The hazard ratio for in-hospital death was 1.03 (95% confidence interval, 0.68-1.56; p = .88) in patients with a first occurrence of hypoglycemia relative to the controls without hypoglycemia, corrected for duration of intensive care unit admittance before hypoglycemia, age, sex, and Acute Physiology and Chronic Health Evaluation II score at admission. No cases of hypoglycemia-associated death were reported. Hypoglycemic coma was reported in two patients. Seizures after hypoglycemia were observed in one patient.

CONCLUSIONS

In this study, no association between incidental hypoglycemia and mortality was found. However, this data set is too small to definitely exclude the possibility that hypoglycemia is associated with intensive care unit mortality. In three patients with possible hypoglycemia-associated coma or seizures, a causal role for hypoglycemia seemed likely but could not fully be established.

Struggle for implementation of new strategies in intensive care medicine: anticoagulation, insulin, and lower tidal volumes

The management of intensive care patients have changed dramatically in the last years: from merely supportive care, it has moved to evidence-based strategies that have been demonstrated to reduce mortality of the severely ill patients. Clinical research have brought numerous positive clinical trials offering intensive care physicians specific therapies to improve outcome of intensive care patients. Among them were the trials that tested the infusion of activated protein C in patients with severe sepsis, tight glycemic control in surgical intensive care patients, and use of lung protective mechanical ventilation by using small tidal volumes in patients with acute lung injury. Although results of these trials were sufficiently strong to, at least, consider implementation of these strategies in critical care medicine, published and yet unpublished reports show that there is significant struggle with implementation of these therapies. This manuscript focuses on the potential reasons that underlie this problem.

Role of nitric oxide in the regulation of glucose kinetics in response to endotoxin in dogs

The purpose of the present in vivo study was to determine the role of nitric oxide (NO) in the regulation of glucose metabolism in response to endotoxin by blocking NO synthesis with N(G)-monomethyl-L-arginine (L-NMMA). In five dogs, the appearance and disappearance rates of glucose (by infusion of [6,6-(2)H(2)]glucose), plasma glucose concentration, and plasma hormone concentrations were measured on five different occasions: saline infusion, endotoxin alone (E coli, 1.0 microg/kg i.v.), and endotoxin administration plus three different doses of primed, continuous infusion of L-NMMA. Endotoxin increased rate of appearance of glucose from 13.7 +/- 1.6 to 23.6 +/- 3.3 micromol x kg(-1) x min(-1) (P < 0.05), rate of disappearance of glucose from 13.9 +/- 1.1 to 24.8 +/- 3.1 micromol x kg(-1) x min(-1) (P < 0.001), plasma lactate from 0.5 +/- 0.1 to 1.7 +/- 0.1 mmol/l (P < 0.01), and counterregulatory hormone concentrations. L-NMMA did not affect the rise in rate of appearance and disappearance of glucose, plasma lactate, or the counterregulatory hormone response to endoxin. Plasma glucose levels were not affected by endotoxin with or without L-NMMA. In conclusion, in vivo inhibition of NO synthesis by high doses of L-NMMA does not affect glucose metabolism in response to endotoxin, indicating that NO is not a major mediator of glucose metabolism during endotoxemia in dogs.

The opiate sufentanil alters the inflammatory, endocrine, and metabolic responses to endotoxin in dogs

Sufentanil is a synthetic mu-opioid receptor agonist frequently used in anesthesia and critically ill patients. To evaluate the effects of sufentanil on the inflammatory, neuroendocrine, and metabolic responses to endotoxin, we studied six dogs during saline infusion (control), during sufentanil infusion (1.5 microg . kg-1 . h-1), after endotoxin injection (1.0 microg/kg iv), and during combined endotoxin and sufentanil administration. The rate of appearance of glucose was determined by infusion of [6,6-2H2]glucose. Sufentanil depressed the endotoxin-induced increase in body temperature (36.9 +/- 0.3 vs. 40.6 +/- 0.5 degrees C, P < 0.05). Sufentanil depressed the tumor necrosis factor (TNF) response to endotoxin by approximately 60% (P < 0.01) but increased the interleukin-6 (IL-6) response by approximately 70% (P < 0.01). Sufentanil per se induced a transient neuroendocrine activation. Sufentanil also increased plasma concentrations of insulin and catecholamines after endotoxin (P < 0.05 vs. endotoxin alone) and increased plasma glucose levels by approximately 36% (from 6.1 +/- 0.1 to 8.3 +/- 0.6 mmol/l, P < 0.05 vs. endotoxin alone). Endotoxin stimulated glucose production transiently by 95% (24.2 +/- 3.2 vs. control 12.4 +/- 1.0 micromol . kg-1 . min-1, P < 0.05). Paradoxically, sufentanil inhibited this endotoxin-induced stimulation of glucose production (P < 0.05 vs. endotoxin alone). In conclusion, sufentanil modulates the response to intravenous endotoxin by dissociating the TNF and IL-6 response, increasing insulin and catecholamine levels, and depressing the increase in glucose production. Therefore, opiates alter inflammatory, endocrine, and metabolic regulation in endotoxemia.

Origin of endotoxemia influences the metabolic response to endotoxin in dogs

Different routes of endotoxin administration have been used to mimic inflammatory and metabolic responses observed during sepsis. Because the origin of endotoxemia may affect the reactions to endotoxin, we compared the induction of tumor necrosis factor (TNF), interleukin-6 (IL-6), hormones, and glucose production after endotoxin (1.0 microg/kg Escherichia coli 0111:B4) administration into a peripheral (n = 8) versus the portal (n = 8) vein in anesthetized dogs. Prior to endotoxin, a laparotomy was performed for cannulation of hepatic vessels. To evaluate the effects of surgery and anesthesia, we also studied the effects of peripheral endotoxin administration in six awake dogs. The rate of appearance of glucose was measured by primed continuous infusion of [6,6-2H2]glucose. In anesthetized dogs, arterial concentrations of TNF and IL-6 increased after endotoxin administration (P < 0.01 vs basal; NS between groups). Net hepatic TNF production was increased after endotoxin administration (peripheral vs portal endotoxin administration: 533 +/- 177 vs 2135 +/- 1127 ng/min, both P < 0.05 vs basal; NS between groups). Net hepatic IL-6 production was stimulated only after portal endotoxin delivery (from 86 +/- 129 to 4740 +/- 1899 ng/min, P < 0.05; NS between groups). Although there were no differences in neuroendocrine activation, portal endotoxin administration resulted in decreased glucose production compared with peripheral administration (13.6 +/- 0.9 vs 16.8 +/- 1.2 micromol/kg.min, P < 0. 05). In contrast to anesthetized dogs, endotoxin increased glucose production considerably in awake dogs from 13.8 +/- 1.2 to 24.2 +/- 3.2 micromol/kg.min (P < 0.05; P < 0.05 vs anesthetized dogs). The contribution of anesthesia and surgery increased the endotoxin-induced IL-6 response by approximately 350% compared with the effect of endotoxin in awake dogs (P < 0.01). In conclusion, there are no major differences in the responses to endotoxin between peripherally treated and portally treated dogs, except for differences in glucose production. Portal delivery compared with systemic delivery of endotoxin alters hepatic metabolism through nonendocrine mechanisms, reflected in decreased glucose production. The inflammatory, endocrine, and metabolic effects of endotoxin are altered by the combination of surgery and anesthesia.

Blunted cortisol response after administration of corticotropin releasing hormone in endotoxemic dogs

To evaluate the effects of a standard inflammatory challenge on the dynamics of the hypothalamic-pituitary-adrenal (HPA) axis, we studied the effects of low-dose endotoxin (1.0 microgram/kg) on plasma adrenocorticotropic hormone (ACTH) and cortisol concentrations in a saline-controlled study in five awake dogs. Four hours after endotoxin or saline challenge human corticotrophin-releasing hormone (hCRH; 1.0 microgram/kg) was administered. Plasma ACTH and cortisol levels increased considerably in response to endotoxin, from 13 +/- 1 ng/l to 360 +/- 85 ng/l (p < 0.01) and from 60 +/- 20 nmol/l to 710 +/- 80 nmol/l (p < 0.01). Despite a considerable difference in ACTH and cortisol levels prior to CRH administration between both studies (p < 0.01), the absolute increase in ACTH levels induced by hCRH was not different (231 +/ 43 ng/l vs 238 +/- 45 ng/l, control vs endotoxin). Plasma cortisol levels increased significantly in the control study (from 40 +/- 10 nmol/l to 330 +/- 40 nmol/l, p < 0.01), whereas they did not change in the endotoxin study after hCRH administration (from 710 +/- 80 nmol/l to 730 +/- 70 nmol/l, ns). We conclude that the HPA-axis reacts initially to endotoxin in such a way that cortisol, but not ACTH, secretion is maximized. Therefore, a blunted cortisol response to CRH testing is part of the initial response to infection.

The influence of alanine infusion on glucose production in 'malnourished' African children with falciparum malaria

By US standards, about half of African children are malnourished, although most appear clinically normal. It is possible that precursor supply for gluconeogenesis is limited to a greater extent in these seemingly malnourished African children than in healthy children, consequently limiting glucose production. Since in malaria peripheral glucose utilization is increased, precursor supply could play an even more critical role in maintaining glucose production in African children suffering from falciparum malaria. We studied the effect of alanine infusion (1.5 mg/kg/min) on glucose production (measured by infusion of [6,6-2H2]glucose) and plasma glucose concentration in 10 consecutive children with acute, uncomplicated falciparum malaria. By US standards, six children were below the 10th percentile of weight for height and seven were below the 10th percentile of height for age. Plasma concentrations of alanine increased during alanine infusion from 153 +/- 21 to 468 +/- 39 mumol/l, whereas plasma lactate concentrations did not change (1.4 +/- 0.2 vs. 1.3 +/- 0.2 mmol/l). Plasma glucose concentration and glucose production did not change during alanine infusion: 4.6 +/- 0.3 vs. 4.5 +/- 0.3 mmol/l and 5.8 +/- 0.4 vs. 5.7 +/- 0.3 mg/kg/min, respectively. Gluconeogenic precursor supply is sufficient for maintainance of glucose production in African children with uncomplicated malaria who are malnourished by US standards.

The decrease in nonsplenic interleukin-6 (IL-6) production after splenectomy indicates the existence of a positive feedback loop of IL-6 production during endotoxemia in dogs

The spleen is involved in endotoxin-induced interleukin-6 (IL-6) production. To quantitate the relative contribution of the spleen to endotoxin-induced IL-6 production, we studied the effect of endotoxin (1.0 microg/kg of body weight) in control dogs (n = 7) and splenectomized dogs (n = 7). Blood for analysis of tumor necrosis factor (TNF) and IL-6 was sampled from the femoral artery and the portal, hepatic, and splenic (only in controls) veins. Arterial plasma endotoxin and cortisol levels were also measured. Whole-body IL-6 production was calculated by a deconvolution technique. Splenic IL-6 production in control dogs was measured from splenic blood flow and arteriovenous concentration differences. Endotoxin levels were higher in splenectomized dogs (P < 0.05) because of a decreased distribution volume (P < 0.05) and decreased clearance of endotoxin (P < 0.05). Endotoxin-induced plasma IL-6 levels were decreased by approximately 75% in splenectomized dogs (P < 0.01), and whole-body IL-6 production rates were severalfold lower (median of 8.7 mg/4 h and range of 3.9 to 11.4 mg/4 h versus a median of 32.3 mg/4 h and a range of 22.7 to 70.2 mg/4 h) (P < 0.05). However, in control dogs splenic IL-6 production (0.6 +/- 0.2 mg/4 h) was only approximately 2% of whole-body IL-6 production. Plasma TNF levels increased in both groups (P < 0.01) but were not different between the groups. Plasma cortisol levels were slightly higher in splenectomized dogs than in control dogs (P < 0.05). In conclusion, splenectomy decreases the distribution volume and clearance rate of endotoxin. Splenectomy results in decreased endotoxin-induced IL-6 production, which is caused not by the absence of splenic IL-6 production, but by a decrease in nonsplenic IL-6 production. Therefore, the spleen is an important mediator in the complete activation of nonsplenic IL-6 production by endotoxin.