Characteristics and outcomes of patients undergoing anesthesia while SARS-CoV-2 infected or suspected: a multicenter register of consecutive patients.

BACKGROUND: There are limited data to detail the perioperative anesthetic management and the incidence of postoperative respiratory complications among patients requiring an anesthetic procedure while being SARS-CoV-2 positive or suspected. METHODS: An observational multicenter cohort study was performed including consecutive patients who were SARS-CoV-2 confirmed or suspected and who underwent scheduled and emergency anesthesia between March 17 and May 26, 2020. RESULTS: A total of 187 patients underwent anesthesia with SARS-CoV-2 confirmed or suspected, with ultimately 135 (72.2%) patients positive and 52 (27.8%) negative. The median SOFA score was 2 [0; 5], and the median ARISCAT score was 49 [36; 67]. The major respiratory complications rate was 48.7% (n = 91) with 40.4% (n = 21) and 51.9% (n = 70) in the SARS-CoV-2-negative and -positive groups, respectively (p = 0.21). Among both positive and negative groups, patients with a high ARISCAT risk score (> 44) had a higher risk of presenting major respiratory complications (p < 0.01 and p = 0.1, respectively). DISCUSSION: When comparing SARS-COV-2-positive and -negative patients, no significant difference was found regarding the rate of postoperative complications, while baseline characteristics strongly impact these outcomes. This finding suggests that patients should be scheduled for anesthetic procedures based on their overall risk of postoperative complication, and not just based on their SARS-CoV-2 status.

Volume Infusion Markedly Increases Femoral dP/dtmax in Fluid-Responsive Patients Only.

OBJECTIVES: To evaluate the preload dependence of femoral maximal change in pressure over time (dP/dtmax) during volume expansion in preload dependent and independent critically ill patients. DESIGN: Retrospective database analysis. SETTING: Two adult polyvalent ICUs. PATIENTS: Twenty-five critically ill patients with acute circulatory failure. INTERVENTIONS: Thirty-five fluid infusions of 500 mL normal saline. MEASUREMENTS AND MAIN RESULTS: Changes in femoral dP/dtmax, systolic, diastolic, and pulse femoral arterial pressure were obtained from the pressure waveform analysis using the PiCCO2 system (Pulsion Medical Systems, Feldkirchen, Germany). Stroke volume index was obtained by transpulmonary thermodilution. Statistical analysis was performed comparing results before and after volume expansion and according to the presence or absence of preload dependence (increases in stroke volume index ≥ 15%). Femoral dP/dtmax increased by 46% after fluid infusion in preload-dependent cases (mean change = 510.6 mm Hg·s; p = 0.005) and remained stable in preload-independent ones (mean change = 49.2 mm Hg·s; p = 0.114). Fluid-induced changes in femoral dP/dtmax correlated with fluid-induced changes in stroke volume index in preload-dependent cases (r = 0.618; p = 0.032), but not in preload-independent ones. Femoral dP/dtmax strongly correlated with pulse and systolic arterial pressures and with total arterial stiffness, regardless of the preload dependence status (r > 0.9 and p < 0.001 in all cases). CONCLUSIONS: Femoral dP/dtmax increased with volume expansion in case of preload dependence but not in case of preload independence and was strongly related to pulse pressure and total arterial stiffness regardless of preload dependence status. Therefore, femoral dP/dtmax is not a load-independent marker of left ventricular contractility and should be not used to track contractility in critically ill patients.

Influence of changes in ventricular systolic function and loading conditions on pulse contour analysis-derived femoral dP/dtmax.

BACKGROUND: Femoral dP/dtmax (maximum rate of the arterial pressure increase during systole) measured by pulse contour analysis has been proposed as a surrogate of left ventricular (LV) dP/dtmax and as an estimator of LV systolic function. However, femoral dP/dtmax may be influenced by LV loading conditions. In this study, we evaluated the impact of variations of LV systolic function, preload and afterload on femoral dP/dtmax in critically ill patients with cardiovascular failure to ascertain its reliability as a marker of LV systolic function. RESULTS: We performed a prospective observational study to evaluate changes in femoral dP/dtmax, thermodilution-derived variables (PiCCO2-Pulsion Medical Systems, Feldkirchen, Germany) and LV ejection fraction (LVEF) measured by transthoracic echocardiography during variations in dobutamine and norepinephrine doses and during volume expansion (VE) and passive leg raising (PLR). Correlations with arterial pulse and systolic pressure, effective arterial elastance, total arterial compliance and LVEF were also evaluated. In absolute values, femoral dP/dtmax deviated from baseline by 21% (201 ± 297 mmHg/s; p = 0.013) following variations in dobutamine dose (n = 17) and by 15% (177 ± 135 mmHg/s; p < 0.001) following norepinephrine dose changes (n = 29). Femoral dP/dtmax remained unchanged after VE and PLR (n = 24). Changes in femoral dP/dtmax were strongly correlated with changes in pulse pressure and systolic arterial pressure during dobutamine dose changes (R = 0.942 and 0.897, respectively), norepinephrine changes (R = 0.977 and 0.941, respectively) and VE or PLR (R = 0.924 and 0.897, respectively) (p < 0.05 in all cases). Changes in femoral dP/dtmax were correlated with changes in LVEF (R = 0.527) during dobutamine dose variations but also with effective arterial elastance and total arterial compliance in the norepinephrine group (R = 0.638 and R = - 0.689) (p < 0.05 in all cases). CONCLUSIONS: Pulse contour analysis-derived femoral dP/dtmax was not only influenced by LV systolic function but also and prominently by LV afterload and arterial waveform characteristics in patients with acute cardiovascular failure. These results suggest that femoral dP/dtmax calculated by pulse contour analysis is an unreliable estimate of LV systolic function during changes in LV afterload and arterial load by norepinephrine and directly linked to arterial waveform determinants.

Effects of two different ventilation strategies on respiratory mechanics during robotic-gynecological surgery.

It is unknown which is the best ventilatory approach in patients scheduled for gynecological robotic surgery in Deep Trendelenburg position in terms of respiratory mechanics. 40 patients were enrolled: 20 patients received a standard ventilation and 20 patients received a protective ventilation. Gas exchanges, respiratory mechanics and hemodynamic parameters were recorded. No significant differences were found between the two groups in terms of respiratory mechanics. In both groups, there was a significant reduction of static compliance between Baseline and Extubation Time (p < 0.01), and a significant increase of pulmonary pressure at the same times (p < 0.01). In both groups, a significant reduction of pH (p < 0.01) and a significant increase of PaCO2 (p < 0.01) were observed between Baseline and Extubation Time. At the Extubation time, PaCO2 was significantly higher during protective ventilation compared to standard ventilation. In this particular surgical setting, a protective ventilation strategy did not improve the respiratory mechanics compared to the standard ventilation strategy and was ineffective on post-operative gas exchanges.

Remifentanil effects on respiratory drive and timing during pressure support ventilation and neurally adjusted ventilatory assist.

We assessed the effects of varying doses of remifentanil on respiratory drive and timing in patients receiving Pressure Support Ventilation (PSV) and Neurally Adjusted Ventilatory Assist (NAVA). Four incrementing remifentanil doses were randomly administered to thirteen intubated patients (0.03, 0.05, 0.08, and 0.1µg·Kg-1·min-1) during both PSV and NAVA. We measured the patient's (Ti/Ttotneu) and ventilator (Ti/Ttotmec) duty cycle, the Electrical Activity of the Diaphragm (EAdi), the inspiratory (Delaytrinsp) and expiratory (Delaytrexp) trigger delays and the Asynchrony Index (AI). Increasing doses of remifentanil did not modify EAdi, regardless the ventilatory mode. In comparison to baseline, remifentanil infusion >0.05µg/Kg-1/min-1 produced a significant reduction of Ti/Ttotneu and Ti/Ttotmec, by prolonging the expiratory time. Delaytrinsp and Delaytrexp were significantly shorter in NAVA, respect to PSV. AI was not influenced by the different doses of remifentanil, but it was significantly lower during NAVA, compared to PSV. In conclusion remifentanil did not affect the respiratory drive, but only respiratory timing, without differences between modes.

The passive leg raising test to guide fluid removal in critically ill patients.

BACKGROUND: To investigate whether haemodynamic intolerance to fluid removal during intermittent renal replacement therapy (RRT) in critically ill patients can be predicted by a passive leg raising (PLR) test performed before RRT. METHODS: We included 39 patients where intermittent RRT with weight loss was decided. Intradialytic hypotension was defined as hypotension requiring a therapeutic intervention, as decided by the physicians in charge. Before RRT, the maximal increase in cardiac index (CI, pulse contour analysis) induced by a PLR test was recorded. RRT was then started. RESULTS: Ultrafiltration rate was similar in patients with and without intradialytic hypotension. Thirteen patients presented intradialytic hypotension, while 26 did not. In patients with intradialytic hypotension, it occurred 120 min [interquartile range 60-180 min] after onset of RRT. In the 26 patients without intradialytic hypotension, the PLR test induced no significant change in CI. Conversely, in patients with intradialytic hypotension, PLR significantly increased CI by 15 % [interquartile range 11-36 %]. The PLR-induced increase in CI predicted intradialytic hypotension with an area under the ROC curve of 0.89 (95 % interval confidence 0.75-0.97) (p < 0.05 from 0.50). The best diagnostic threshold was 9 %. The sensitivity was 77 % (95 % confidence interval 46-95 %), the specificity was 96 % (80-100 %), the positive predictive value was 91 % (57-100 %), and the negative predictive value was 89 % (72-98 %). Compared to patients without intolerance to RRT, CI decreased significantly faster in patients with intradialytic hypotension, with a slope difference of -0.17 L/min/m(2)/h. CONCLUSION: The presence of preload dependence, as assessed by a positive PLR test before starting RRT with fluid removal, predicts that RRT will induce haemodynamic intolerance.

A cannabinoid-intoxicated child treated with dexmedetomidine: a case report.

INTRODUCTION: In the last 20 years, the rate of exposure to marijuana has increased dramatically, even in the pediatric population. Effects of intoxication are variable, more severe neurological symptoms can be observed following ingestion, thus hospital or intensive care unit admission is often required. Usually cannabinoids intoxicated patients are treated with administration of benzodiazepines or opioids, accepting the related risk of intubation and mechanical ventilation. Dexmedetomidine is a highly selective α2-adrenergic receptor agonist, with no effect on the respiratory drive and pattern and produces a good level of sedation, allowing to avoid the administration of other sedatives. To our knowledge, this is the first reported case of dexmedetomidine use to support a cannabis intoxicated patient. CASE PRESENTATION: A 19-month-old Caucasian boy was presented to our emergency department. At the time of his arrival, he was somnolent with paroxysms of agitation, breathing spontaneously and hemodynamically stable. The results of all investigations were negative, but the result of the immunochemical screening of his urine was positive for Δ(9)-tetrahydrocannabinol. The patient was admitted to the pediatric intensive care unit and treated with a continuous infusion of dexmedetomidine. CONCLUSIONS: Dexmedetomidine is a fairly safe and effective antidote for pediatric marijuana or natural cannabinoid exposures. Its properties and potential to allow for "cooperative" sedation make it a more attractive choice with fewer side effects than benzodiazepines or opioids.

Influence of different interfaces on synchrony during pressure support ventilation in a pediatric setting: a bench study.

BACKGROUND: In adults and children, patient-ventilator synchrony is strongly dependent on both the ventilator settings and interface used in applying positive pressure to the airway. The aim of this bench study was to determine whether different interfaces and ventilator settings may influence patient-ventilator interaction in pediatric models of normal and mixed obstructive and restrictive respiratory conditions. METHODS: A test lung, connected to a pediatric mannequin using different interfaces (endotracheal tube [ETT], face mask, and helmet), was ventilated in pressure support ventilation mode testing 2 ventilator settings (pressurization time [Timepress]50%/cycling-off flow threshold [Trexp]25%, Timepress80%/Trexp60%), randomly applied. The test lung was set to simulate one pediatric patient with a healthy respiratory system and another with a mixed obstructive and restricted respiratory condition, at different breathing frequencies (f) (30, 40, and 50 breaths/min). We measured inspiratory trigger delay, pressurization time, expiratory trigger delay, and time of synchrony. RESULTS: At each breathing frequency, the helmet showed the longest inspiratory trigger delay compared with the ETT and face mask. At f30, the ETT had a reduced Tpress. The helmet had the shortest Tpress in the simulated child with a mixed obstructive and restricted respiratory condition, at f40 during Timepress50%/Trexp25% and at f50 during Timepress80%/Trexp60%. In the simulated child with a normal respiratory condition, the ETT presented the shortest Tpress value at f50 during Timepress80%/Trexp60%. Concerning the expiratory trigger delay, the helmet showed the best interaction at f30, but the worst at f40 and at f50. The helmet showed the shortest time of synchrony during all ventilator settings. CONCLUSIONS: The choice of the interface can influence patient-ventilator synchrony in a pediatric model breathing at increased f, thus making it more difficult to set the ventilator, particularly during noninvasive ventilation. The helmet demonstrated the worst interaction, suggesting that the face mask should be considered as the first choice for delivering noninvasive ventilation in a pediatric model.

A bench study of 2 ventilator circuits during helmet noninvasive ventilation.

OBJECTIVE: To compare helmet noninvasive ventilation (NIV), in terms of patient-ventilator interaction and performance, using 2 different circuits for connection: a double tube circuit (with one inspiratory and one expiratory line) and a standard circuit (a Y-piece connected only to one side of the helmet, closing the other side). METHODS: A manikin, connected to a test lung set at 2 breathing frequencies (20 and 30 breaths/min), was ventilated in pressure support ventilation (PSV) mode with 2 different settings, randomly applied, of the ratio of pressurization time to expiratory trigger time (T(press)/T(exp-trigger)) 50%/25%, default setting, and T(press)/T(exp-trigger) 80%/60%, fast setting, through a helmet. The helmet was connected to the ventilator randomly with the double and the standard circuit. We measured inspiratory trigger delay (T(insp-delay)), expiratory trigger delay (T(exp-delay)), T(press)), time of synchrony (T(synch)), trigger pressure drop, inspiratory pressure-time product (PTP), PTP at 300 ms and 500 ms, and PTP at 500 ms expressed as percentage of an ideal PTP500 (PTP500 index). RESULTS: At both breathing frequencies and ventilator settings, helmet NIV with the double tube circuit showed better patient-ventilator interaction, with shorter T(insp-delay), T(exp-delay), and T(press); longer T(synch); and higher PTP300, PTP500, and PTP500 index (all P < .01). CONCLUSIONS: The double tube circuit had significantly better patient-ventilator interaction and a lower rate of wasted effort at 30 breaths/min.