Effects of hyperoxemia in patients with sepsis - A post-hoc analysis of a multicentre randomized clinical trial

BACKGROUND

Administration of supplemental oxygen is a life-saving treatment in critically ill patients. Still, optimal dosing remains unclear during sepsis. The aim of this post-hoc analysis was to assess the association between hyperoxemia and 90-day mortality in a large cohort of septic patients.

METHODS

This is a post-hoc analysis of the Albumin Italian Outcome Sepsis (ALBIOS) randomized controlled trial (RCT). Patients with sepsis who survived the first 48 h since randomization were included and stratified into two groups according to their average PaO₂ levels during the first 48 h (PaO_{2 0-48 h}). The cut-off value was established at 100 mmHg (average PaO_{2 0-48 h} >100 mmHg: hyperoxemia group; PaO_{2 0-48h}≤100: normoxemia group). The primary outcome was 90-day mortality.

RESULTS

1632 patients were included in this analysis (661 patients in the hyperoxemia group, 971 patients in the normoxemia group). Concerning the primary outcome, 344 (35.4%) patients in the hyperoxemia group vs. 236 (35.7%) in the normoxemia group had died within 90 days from randomization (p = 0.909). No association was found after adjusting for confounders (HR 0.87; CI [95%] 0.736-1.028, p = 0.102) or after excluding patients with hypoxemia at enrollment, patients with lung infection or including post-surgical patients only. Conversely, we found an association between lower risk of 90-day mortality and hyperoxemia in the subgroup including patients who had the lung as primary site of infection (HR 0.72; CI [95%] 0.565-0.918). Mortality at 28 days, ICU mortality, incidence of acute kidney injury, use of renal replacement therapy, days to suspension of vasopressor or inotropic agents, and resolution of primary and secondary infections did not differ significantly. Duration of mechanical ventilation and length of stay in ICU were significantly longer in patients with hyperoxemia.

CONCLUSIONS

In a post-hoc analysis of a RCT enrolling septic patients, hyperoxemia as average PaO₂>100 mmHg during the first 48 h was not associated with patients' survival.

Prevalence and features of delirium in older patients admitted to rehabilitation facilities: a multicenter study

BACKGROUND

Delirium is thought to be common across various settings of care; however, still little research has been conducted in rehabilitation.

AIM

We investigated the prevalence of delirium, its features and motor subtypes in older patients admitted to rehabilitation facilities during the three editions of the "Delirium Day project".

METHODS

We conducted a cross-sectional study in which 1237 older patients (age ≥ 65 years old) admitted to 50 Italian rehabilitation wards during the three editions of the "Delirium Day project" (2015 to 2017) were included. Delirium was evaluated through the 4AT and its motor subtype with the Delirium Motor Subtype Scale.

RESULTS

Delirium was detected in 226 patients (18%), and the most recurrent motor subtype was mixed (37%), followed by hypoactive (26%), hyperactive (21%) and non-motor one (16%). In a multivariate Poisson regression model with robust variance, factors associated with delirium were: disability in basic (PR 1.48, 95%CI: 1.17-1.9, p value 0.001) and instrumental activities of daily living (PR 1.58, 95%CI: 1.08-2.32, p value 0.018), dementia (PR 2.10, 95%CI: 1.62-2.73, p value < 0.0001), typical antipsychotics (PR 1.47, 95%CI: 1.10-1.95, p value 0.008), antidepressants other than selective serotonin reuptake inhibitors (PR 1.3, 95%CI: 1.02-1.66, p value 0.035), and physical restraints (PR 2.37, 95%CI: 1.68-3.36, p value < 0.0001).

CONCLUSION

This multicenter study reports that 2 out 10 patients admitted to rehabilitations had delirium on the index day. Mixed delirium was the most prevalent subtype. Delirium was associated with unmodifiable (dementia, disability) and modifiable (physical restraints, medications) factors. Identification of these factors should prompt specific interventions aimed to prevent or mitigate delirium.

The association between low skeletal muscle mass and delirium: results from the nationwide multi-centre Italian Delirium Day 2017

Introduction

Delirium and sarcopenia are common, although underdiagnosed, geriatric syndromes. Several pathological mechanisms can link delirium and low skeletal muscle mass, but few studies have investigated their association. We aimed to investigate (1) the association between delirium and low skeletal muscle mass and (2) the possible role of calf circumference mass in finding cases with delirium.

Methods

The analyses were conducted employing the cross-sectional “Delirium Day” initiative, on patient 65 years and older admitted to acute hospital medical wards, emergency departments, rehabilitation wards, nursing homes and hospices in Italy in 2017. Delirium was diagnosed as a 4 + score at the 4-AT scale. Low skeletal muscle mass was operationally defined as calf circumference ≤ 34 cm in males and ≤ 33 cm in females. Logistic regression models were used to investigate the association between low skeletal muscle mass and delirium. The discriminative ability of calf circumference was evaluated using non-parametric ROC analyses.

Results

A sample of 1675 patients was analyzed. In total, 73.6% of participants had low skeletal muscle mass and 24.1% exhibited delirium. Low skeletal muscle mass and delirium showed an independent association (OR: 1.50; 95% CI 1.09–2.08). In the subsample of patients without a diagnosis of dementia, the inclusion of calf circumference in a model based on age and sex significantly improved its discriminative accuracy [area under the curve (AUC) 0.69 vs 0.57, p < 0.001].

Discussion and conclusion

Low muscle mass is independently associated with delirium. In patients without a previous diagnosis of dementia, calf circumference may help to better identify those who develop delirium.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40520-021-01950-8.

PCSK9 is associated with mortality in patients with septic shock: data from the ALBIOS study

BACKGROUND

Pro-protein convertase subtilisin/kexin 9 (PCSK9) is a proenzyme primarily known to regulate low-density lipoprotein receptor re-uptake on hepatocytes. Whether PCSK9 can concurrently trigger inflammation or not remains unclear. Here, we investigated the potential association between circulating levels of PCSK9 and mortality in patients with severe sepsis or septic shock.

METHODS

Plasma PCSK9 levels at days 1, 2 and 7 were measured in 958 patients with severe sepsis or septic shock previously enrolled in the Albumin Italian Outcome Sepsis (ALBIOS) trial. Correlations between levels of PCSK9 and pentraxin 3 (PTX3), a biomarker of disease severity, were evaluated with ranked Spearman's coefficients. Cox proportional hazards models were used to assess the association of PCSK9 levels at day 1 with 28- and 90-day mortality.

RESULTS

Median plasma PCSK9 levels were 278 [182-452] ng mL^-1 on day 1. PCSK9 correlated positively with PTX3 at the three time-points, and patients with septic shock within the first quartile of PCSK9 showed higher levels of PTX3. Similar mortality rates were observed in patients with severe sepsis across PCSK9 quartiles. Patients with septic shock with lower PCSK9 levels on day 1 (within the first quartile) showed the highest 28- and 90-day mortality rate as compared to other quartiles.

CONCLUSION

In our sub-analysis of the ALBIOS trial, we found that patients with septic shock presenting with lower plasma PCSK9 levels experienced higher mortality rate. Further studies are warranted to better evaluate the pathophysiological role of PCSK9 in sepsis.

Transient paraplegia due to subarachnoid haemorrhage following spinal anaesthesia

Spinal subarachnoid haemorrhage is a rare complication of spinal anaesthesia, especially following atraumatic lumbar puncture and in the absence of coagulopathies. The initial presentation of spinal subarachnoid haemorrhage is variable and paraplegia with full recovery within a few hours is rare. Bleeding can extend into the intracranial subarachnoid space, but there are only a few reports of symptomatic intracranial and spinal subarachnoid haemorrhage after spinal anaesthesia. We report co-existing spinal subarachnoid haemorrhage and intracranial subarachnoid haemorrhage after atraumatic spinal anaesthesia in a 69-year-old woman without a coagulopathy. The day after surgery she developed flaccid paraplegia that spontaneously resolved in a few hours. Magnetic resonance imaging demonstrated subarachnoid high signal intensity from T11-S2, consistent with spinal subarachnoid haemorrhage. On the same day the patient complained of severe headache which was later followed by diplopia. Neurological imaging studies revealed diffuse distribution of blood in the subarachnoid space but no intracranial vascular malformations. At the time of diagnosis spontaneous recovery of spinal symptoms had already begun and the clinical manifestations eventually resolved with conservative management. The possibility of an intracranial haemorrhage should always be considered when spinal subarachnoid haemorrhage is identified, even in cases of uncomplicated spinal anaesthesia in patients with no known risk factors for spinal haemorrhage.

Kidney instant monitoring (K.IN.G): a new analyzer to monitor kidney function

AIM

The key role of the kidney in the regulation of body fluids and acid-base status is well known. Nonetheless, urine analysis has not received great attention in critically ill patients, likely due to the common practice of only analyzing 24-hour collected specimens. We hypothesized that the kidney may react more rapidly to minimal hemodynamic and acid-base status variations than can be assessed by a 24-hour analysis. Accordingly, we developed and tested a urine analyzer, allowing quasi-continuous urinary analysis.

METHODS

A novel analyzer (Kidney INstant monitorinG--K.IN.G) was developed that allows non-invasive, quasi-continuous analysis of urine pH, sodium, chloride, potassium and ammonium levels. Analytic measurement accuracy was calculated for urine samples of patients admitted to ICUs as well as medical staff, using standard techniques as references. For clinical investigation, approximately 200 patients were connected to the analyzer after ICU admission until discharge. Clinically relevant parameters were recorded. Here, three cases are presented.

RESULTS

For each analytic parameter, the accuracy of measurements obtained with the K.IN.G analyzer appeared to be acceptable as compared to those of the reference techniques. In case 1, urine analysis revealed increased urinary sodium and chloride excretion strictly in parallel with mean arterial pressure, and increased ammonium excretion which was associated with moderate hypercapnia. Case 2 showed increases in urinary pH and sodium and chloride levels following awakening after sedation suspension. In case 3, urine analysis revealed an impairment of renal concentrative power, which was associated with hypovolemia.

CONCLUSION

The K.IN.G analyzer, allowing quasi-continuous monitoring of urinary pH and principal electrolyte levels, may represent a novel tool for clinical and research purposes.

The ratio between arterio-venous PCO2 difference and arterio-jugular oxygen difference as estimator of critical cerebral hypoperfusion

AIM

The aim of this study was to evaluate the arterio-venous difference in carbon dioxide tension (DPCO2) and the ratio between DPCO2 and arterio-jugular oxygen difference (AJDO2) as indicators of compensated or uncompensated cerebral hypoperfusion.

METHODS

Cerebral blood flow (CBF) was reduced stepwise in 6 pigs by inducing intracranial hypertension with consequently cerebral perfusion pressure (CPP) reduction: CBF 100%, 50-60 % of baseline, 20-30% of baseline. Intracranial pressure (ICP), mean arterial pressure (MAP), CPP and CBF (laser-Doppler method) were continuously recorded. Superior sagittal sinus was punctured for the determination of AJDO2 and DPCO2.

RESULTS

CBF impairment was accompanied by changes in AJDO2 from 6.03 +/- 1.21 vol% to 7.32 +/- 1.30 vol%, up to 8.07 +/- 1.32 vol% (P < 0.01), in DPCO2 from 12.17 +/- 3.25 mmHg to 16 +/- 4.12 mmHg, up to 26.5 +/- 6.41 mmHg (P < 0.01), and DPCO2/AJDO2 ratio from 2.05 +/- 0.39 to 2.06 +/- 0.72 up to 3.41 +/- 1.09 in the 3 phases (P < 0.05).

CONCLUSIONS

When CBF declines AJDO2 increases, indicating greater extraction of O2 to satisfy aerobic metabolism. However, this mechanism can no longer compensate once a critical CBF threshold is reached. DPCO2 rises slowly during moderate CBF reduction because of defective washout; the rise is steeper during marked CBF impairment when anaerobic metabolism takes place. During cerebral hypoperfusion the venous blood gases and acid base variables mirror the degree of cerebral perfusion. In particular the DPCO2, and the DPCO2/ AJDO2 ratio may be useful markers of critical brain hypoperfusion.

Recruitment and derecruitment during acute respiratory failure: a clinical study

In a model of acute lung injury, we showed that positive end-expiratory pressure (PEEP) and tidal volume (VT) are interactive variables that determine the extent of lung recruitment, that recruitment occurs across the entire range of total lung capacity, and that superimposed pressure is a key determinant of lung collapse. Aiming to verify if the same rules apply in a clinical setting, we randomly ventilated five ALI/ARDS patients with 10, 15, 20, 30, 35, and 45 cm H2O plateau pressure and 5, 10, 15, and 20 cm H2O of PEEP. For each PEEP-VT condition, we obtained computed tomography at end inspiration and end expiration. We found that recruitment occurred along the entire volume-pressure curve, independent of lower and upper inflection points, and that estimated threshold opening pressures were normally distributed (mode = 20 cm H2O). Recruitment occurred progressively from nondependent to dependent lung regions. Overstretching was not associated with hyperinflation. Derecruitment did not parallel deflation, and estimated threshold closing pressures were normally distributed (mode = 5 cm H2O). End-inspiratory and end-expiratory collapse were correlated, suggesting a plateau-PEEP interaction. When superimposed gravitational pressure exceeded PEEP, end-expiratory collapse increased. We concluded that the rules governing recruitment and derecruitment equally apply in an oleic acid model and in human ALI/ARDS.

Recruitment and derecruitment during acute respiratory failure: an experimental study

We aimed to elucidate the relationships between pleural (Ppl), esophageal (Pes), and superimposed gravitational pressures in acute lung injury, and to understand the mechanisms of recruitment and derecruitment. In six dogs with oleic acid respiratory failure, we measured Pes and Ppl in the uppermost, middle, and most dependent lung regions. Each dog was studied at positive end-expiratory pressure (PEEP) of 5 and 15 cm H2O and three levels of tidal volume (VT; low, medium, and high). For each PEEP-VT combination, we obtained a computed tomographic (CT) scan at end-inspiration and end-expiration. The variations of Ppl and Pes pressures were correlated (r = 0.86 +/- 0.07, p < 0.0001), as was the vertical gradient of transpulmonary (PL) and superimposed pressure (r = 0.92, p < 0.0001). Recruitment proceeded continuously along the entire volume-pressure curve. Estimated threshold opening pressures were normally distributed (mode = 20 to 25 cm H2O). The amount of end-expiratory collapse at the same PEEP and PL was significantly lower when ventilation was performed at high VT. End-inspiratory and end-expiratory collapse were highly correlated (r = 0.86, p < 0.0001), suggesting that as more tissue is recruited at end-inspiration, more remains recruited at end-expiration. When superimposed pressure exceeded applied airway pressure (Paw), collapse significantly increased.

Pathophysiology of prone positioning in the healthy lung and in ALI/ARDS

Prone position was initially introduced in healthy anesthetized and paralyzed subjects for surgical specific reasons. Then, it was used during acute respiratory failure to improve gas exchange. The interest on prone position during ALI/ARDS progressively increased, even if the mechanisms leading to a respiratory improvement are not yet completely understood. In normal subjects, during anesthesia and paralysis, prone position determines a more homogeneous distribution of the gravitational gradient of alveolar inflation, a ventilation distributed towards the non dependent lung regions and a reverse of the gravitational distribution of regional perfusion, even if factors other than gravity are involved. Moreover, prone position causes, both in healthy subject and in obese patients, an improvement in oxygenation and in functional residual capacity without affecting respiratory system, lung and chest wall compliance. In ALI/ARDS patients, prone position lead to a reverse of the alveolar inflation and ventilation distribution, due to the reverse of hydrostatic pressure overlying lung parenchyma, the reverse of heart weight, and the changes in chest wall shape and mechanical properties. Little data are available for the modifications in regional lung perfusion. The possible mechanisms involved in oxygenation improvement during prone position in ALI/ARDS patients are: 1) increased lung volumes; 2) redistribution of lung perfusion; 3) recruitment of dorsal spaces with more homogeneous ventilation and perfusion distribution. From a clinical point of view, prone position seems to be a very promising treatment for ALI/ARDS, even if its use is not yet a standard clinical practice. We have recently finished a randomized-controlled trial in order to investigate the clinical impact of this procedure. In the preliminary phase of the study performed in 35 Italian Intensive Care Units, we studied, from 1996 to 1998, 73 patients with a PaO2/FiO2 of 123 +/- 42 and a SAPS (Simplified Acute Physiology Score) of 38 +/- 11. After the first hour of prone positioning, the PaO2/FiO2 ratio of 76% of the patients had increased by more than 20 mmHg (responder) with a mean increase of 78 +/- 53 mmHg. The proportion of responders increased to 85% after 6 hours of prone positioning. The incidence of maneuver-related complications and severe and life-threatening complications was extremely rare. The overall mortality at ICU discharge was 51% and the ICU stay was similar in survivors and non survivors (17.8 +/- 11.6 vs 17.8 +/- 11.4 days).

Pulmonary and Extrapulmonary Forms of Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is usually viewed as the functional and morphological expression of a similar underlying lung injury caused by a variety of insults. However, the distinction between ARDS due to a direct (ARDSp) versus an indirect (ARDSexp) lung injury is gaining more attention as a means of better comprehending the pathophysiology of ARDS and for modifying ventilatory management. From the few published studies, we can summarize that: (1) the prevalent damage in early stages of a direct insult is intra-alveolar, whereas in indirect injury it is the interstitial edema. It is possible that the two insults may coexist (i.e., one lung with direct injury (as in pneumonia) and the other with indirect injury, through mediator release from the contralateral pneumonia); (2) the radiological pattern, by chest x-ray or computed tomography (CT), is different in ARDSp (characterized by prominent consolidation) and ARDSexp (characterized by prominent ground-glass opacification); (3) in ARDSp lung elastance is more markedly increased than in ARDSexp, where the main abnormality is the increase in chest wall elastance, due to abnormally high intra-abdominal pressure; (4) positive end-expiratory pressure (PEEP), inspiratory recruitment, and prone position are more effective to improve respiratory mechanics, alveolar recruitment, and gas-exchange in ARDSexp. Further studies are warranted to better define if the distinction between ARDS of different origins can improve clinical management and survival.

[Mechanical ventilation in acute respiratory distress syndrome. New Trends]

Adult Respiratory Distress Syndrome (ARDS) is characterized by an inflammatory process affecting endothelial and epithelial lung tissue, with occurrence of hypoxemia, bilateral X-ray infiltrates, in absence of cardiogenic edema. The introduction of Computerized Tomography brought some improvements in understanding the ARDS lung, leading to a pulmonary model made up of three zones: 1) normally inflated, 2) recruitable and 3) consolidated. It has now been well established that mechanical ventilation of ARDS lung presents some iatrogenic effects that may affect mortality. Several mechanisms are considered responsible of ventilator-associated lung injury (VALI): high inspired oxygen fraction, high inspiratory plateau pressure and large tidal volume, and intratidal collapse and reinflation of alveolar units. In these years, different ventilatory strategies in the treatment of ARDS patients have been suggested to decrease and to prevent VALI. The most important one seems to be the application of an appropriate value of tidal volume and positive end-expiratory pressure (PEEP). Several randomized studies, which compared low versus high tidal volumes, have recently been finished. Despite some differences, it seems that a ventilatory management limiting inspiratory plateau pressure to 35 cmH2O or lower may be useful to reduce VALI and mortality, also in association with a PEEP level sufficient to decrease the end-expiratory collapse. Another useful ventilatory tool for improving gas exchange and decreasing VALI in ARDS patients is likely the prone positioning, even if further studies are necessary to understand how this maneuver may really affect mortality. Another therapeutic instrument for improving oxygenation in ARDS patients is the inhalation of NO. Unfortunately, this pharmacological agent does not seem to affect the outcome of these patients.

[Positive end expiratory pressure in anesthesia]

It is well established that general anesthesia, with or without paralysis, causes profound changes in respiratory function. From a clinical point of view, the more important consequence of this impairment is a decreased efficiency of gas exchange, with a decreased blood oxygenation. The main reason of this respiratory embarrassment is the intraoperative occurrence of atelectasis, mainly in the dependent lung regions. The amount of atelectasis, computed through Computerized Tomography, correlates with the amount of intrapulmonary shunt; thus, alveolar collapse and ventilation/perfusion mismatching are considered the most important factors for poor respiratory function. This deterioration seems also to play a crucial role in obese patients, who have poorer respiratory function and gas exchange than normal subjects already in physiological conditions. Different ventilatory approaches have been tried to resolve and eventually prevent the anesthesia-induced atelectasis. In normal subjects, the sole application of positive end-expiratory pressure (PEEP) seems to be an useless tool for improving gas exchange, probably because of changes in hemodynamics functions. The only effective application of PEEP seems to be in association to an alveolar recruitment manoeuvre. As the anesthesia-induced atelectasis are also present in the postoperative period, this ventilatory approach may also be used to prevent this condition. In obese patients PEEP seems to have a major effectiveness than in normal subjects, with an improvement of lung volumes, respiratory mechanics, gas exchange and an occurrence of recruitment. However, further studies are necessary to define optimal value of PEEP and tidal volume for different types of patients.

[Anxiety and stress in the nursing staff. A comparative study between intensive care and general wards]

We studied a population of 463 nurses working in intensive care units--ICUs--(distributed in 51 italian hospitals), and 216 nurses working in general medicine units (distributed in 17 italian hospitals). They we asked to fill in a form including: 1) general data and his/her work environment, and 2) some standardized scales (HAD A and D, STAI Y-1 and Y-2, MBI) for estimation of anxiety, depression and "burnout" syndrome. We used also the "P questions", evaluating the different situations of work environment causing anxiety. The aims of the study were to evaluate the effectiveness of different scales and the influence of general medicine and intensive care environment on psychological features. Among different scales estimating anxiety, the STAI Y-2, valuing a chronic anxiety status, results to be efficient, beside the already tested HAD A. The intensive care environment did not seem to be more stressful for nurses staff rather than general medicine units. Furthermore, nurses operating in general medicine units have a major tendency to depression; their work environment seems to favour the development of anxiety. Finally, it results that general medicine units cause a more severe "burnout" syndrome in their nurses staff rather than ICUs.