Cerebral herniation associated with central venous catheter insertion: risk assessment

Hippocampal Damage During Mechanical Ventilation in Trendelenburg Position: A Secondary Analysis of an Experimental Study on the Prevention of Ventilator-Associated Pneumonia

We previously corroborated benefits of the Trendelenburg position in the prevention of ventilator-associated pneumonia (VAP). We now investigate its potential effects on the brain versus the semirecumbent position. We studied 17 anesthetized pigs and randomized to be ventilated and positioned as follows: duty cycle (TI/TTOT) of 0.33, without positive end-expiratory pressure (PEEP), placed with the bed oriented 30° in anti-Trendelenburg (control group); positioned as in the control group, with TI/TTOT adjusted to achieve an expiratory flow bias, PEEP of 5 cm H2O (IRV-PEEP); positioned in 5° TP and ventilated as in the control group (TP). Animals were challenged into the oropharynx with Pseudomonas aeruginosa. We assessed hemodynamic parameters and systemic inflammation throughout the study. After 72 h, we evaluated incidence of microbiological/histological VAP and brain injury. Petechial hemorrhages score was greater in the TP group (P = 0.013). Analysis of the dentate gyrus showed higher cell apoptosis and deteriorating neurons in TP animals (P < 0.05 vs. the other groups). No differences in systemic inflammation were found among groups. Cerebral perfusion pressure was higher in TP animals (P < 0.001), mainly driven by higher mean arterial pressure. Microbiological/histological VAP developed in 0%, 67%, and 86% of the animals in the TP, control, and IRV-PEEP groups, respectively (P = 0.003). In conclusion, the TP prevents VAP; yet, we found deleterious neural effects in the dentate gyrus, likely associated with cerebrovascular modification in such position. Further laboratory and clinical studies are mandatory to appraise potential neurological risks associated with long-term TP.

Intraosseous Administration of 23.4% NaCl for Treatment of Intracranial Hypertension

BACKGROUND/OBJECTIVE

Prompt treatment of acute intracranial hypertension is vital to preserving neurological function and frequently includes administration of 23.4% NaCl. However, 23.4% NaCl administration requires central venous catheterization that can delay treatment. Intraosseous catheterization is an alternative route of venous access that may result in more rapid administration of 23.4% NaCl.

METHODS

Single-center retrospective analysis of 76 consecutive patients, between January 2015 and January 2018, with clinical signs of intracranial hypertension received 23.4% NaCl through either central venous catheter or intraosseous access.

RESULTS

Intraosseous cannulation was successful on the first attempt in 97% of patients. No immediate untoward effects were seen with intraosseous cannulation. Time to treatment with 23.4% NaCl was significantly shorter in patients with intraosseous access compared to central venous catheter (p < 0.0001).

CONCLUSIONS

Intraosseous cannulation resulted in more rapid administration of 23.4% NaCl with no immediate serious complications. Further investigations to identify the clinical benefits and safety of hypertonic medication administration via intraosseous cannulation are warranted.

Predicting Fluid Responsiveness in Acute Liver Failure: A Prospective Study

BACKGROUND

The profound hemodynamic changes seen in acute liver failure (ALF) resemble the hyperdynamic state found in the later stages of septic shock. Vasopressor support frequently is required after initial volume therapy. Markers of preload dependency have not been studied in this patient group. Dynamic maneuvers such as passive leg raising or end-expiratory hold, which have shown good predictive accuracy in a general intensive care unit population, cannot be considered safe in this cohort because of the concerns of intracranial hypertension.

METHODS

Mechanically ventilated patients with ALF admitted to a tertiary specialist intensive care unit in shock and multiorgan failure were enrolled. Markers of fluid responsiveness derived from transpulmonary thermodilution, pulse contour analysis, and echocardiography were compared between responders (cardiac index ≥15%) and nonresponders to a colloid fluid challenge (5 mL/kg predicted body weight). The ability to predict fluid responsiveness of stroke volume variation, pulse pressure variation (PPV), and respiratory change in peak (delta V peak) left ventricular outflow tract velocity for preload dependency were analyzed.

RESULTS

Thirty-five patients (mean ± SD age, 38 [14] years, 13 male, 22 female]) were assessed after a single fluid challenge. Ten patients (29%) were fluid responders. Changes in cardiac index and stroke volume index in the cohort of 35 patients were correlated (R = 0.726 [99% confidence interval, 0.401-0.910]; P < .001). PPV predicted fluid responsiveness (area under the receiver operating characteristic curve [AUROC], 0.752 [95% confidence interval, 0.565-0.889]; P = .005; cutoff >9%). The AUROC for stroke volume variation was 0.678 ([95% confidence interval, 0.499-0.825]; P = .084; cutoff >11%). The AUROC for [delta] V peak before fluid bolus was 0.637 (95% confidence interval, 0.413-0.825; P = .322).

CONCLUSIONS

PPV based on pulse contour analysis predicted fluid responsiveness in ALF.

What a Nephrologist Needs to Know About Acute Liver Failure

Although relatively rare in the United States, acute liver failure (ALF) is associated with very high rates of morbidity and mortality. A leading cause of morbidity and mortality is cerebral edema and intracranial hypertension. Hypothermia, osmotic diuretics, and hyperosmolar therapy are commonly used to manage these complications; however, when these are ineffective, renal replacement therapy may be needed for volume management. Acute kidney injury is a common complication of ALF and may arise from a number of etiologies, including hepatorenal syndrome and acute tubular necrosis. Acute kidney injury is most common in patients who develop ALF because of acetaminophen toxicity or ischemia. With regard to renal replacement therapy, we will review specific considerations relevant to the management of the patient with ALF.

Recognising air embolism as a complication of vascular access

The insertion and maintenance of advanced vascular access devices is increasingly becoming the remit of advanced nurses. Understanding the potential for air embolism as a complication of this procedure, recognising and managing the signs and symptoms, and being able to apply preventative measures, are imperative to enhance patient safety. A range of outcomes can present from air embolism depending on the rate and volume of air entrained, from sub-clinical to death, so the application of expert knowledge and vigilance is essential to minimise risk. According the the available literature, supplemental oxygen administration appears to be the most effective treatment.

Correlation of caval index, inferior vena cava diameter, and central venous pressure in shock patients in the emergency room

Objectives

This study aims to determine the correlation of the caval index, inferior vena cava (IVC) diameter, and central venous pressure (CVP) in patients with shock in the emergency room.

Materials and methods

This is a prospective double-blind observational study conducted in the emergency room of a tertiary care center. All patients who presented with shock and had a central venous catheter insertion performed were enrolled. The caval index was calculated as a relative decrease in the IVC diameter during the normal respiratory cycle. The correlation of CVP and the caval index were calculated by Pearson’s product–moment correlation coefficient.

Results

Among the 30 patients enrolled, the median age was 59.90±21.81 years and 17 (56.7%) patients were men. The summary statistics that were generated for the participants’ characteristics were divided into CVP <10 cm H₂O, 10–15 cm H₂O, and >15 cm H₂O. The correlation of the CVP measurement with the ultrasound IVC caval index was r=−0.721 (P=0.000) by two-dimensional mode ultrasound and r=−0.647 (P=0.001) by M-mode. The correlations of CVP with the end-expiratory IVC diameter were r=0.551 (P=0.002) by two-dimensional mode ultrasound and r=0.492 (P=0.008) by M-mode. The sensitivity and specificity of the caval index were calculated to predict the CVP. The results showed that the cut-off points of the caval index were 30, 20, and 10 at CVP levels <10 cm H₂O, 10–15 cm H₂O, and >15 cm H₂O, respectively.

Conclusion

The caval index calculated from the IVC diameter measured by bedside ultrasound in the emergency room has a good correlation with CVP.