Intraoperative diagnosis of type 1 diabetes and diabetic ketoacidosis during scoliosis surgery.

Diabetic ketoacidosis is the leading cause of morbidity and mortality in children with type 1 diabetes. Management of diabetic ketoacidosis requires meticulous monitoring and treatment of severe dehydration and metabolic derangement. We present an adolescent patient who was diagnosed with diabetic ketoacidosis during spinal fusion for idiopathic scoliosis and discuss the management of this unexpected intraoperative emergency.

Peripheral Intravenous Waveform Analysis Responsiveness to Subclinical Hemorrhage in a Rat Model.

BACKGROUND: Early detection and quantification of perioperative hemorrhage remains challenging. Peripheral intravenous waveform analysis (PIVA) is a novel method that uses a standard intravenous catheter to detect interval hemorrhage. We hypothesize that subclinical blood loss of 2% of the estimated blood volume (EBV) in a rat model of hemorrhage is associated with significant changes in PIVA. Secondarily, we will compare PIVA association with volume loss to other static, invasive, and dynamic markers. METHODS: Eleven male Sprague Dawley rats were anesthetized and mechanically ventilated. A total of 20% of the EBV was removed over ten 5 minute-intervals. The peripheral intravenous pressure waveform was continuously transduced via a 22-G angiocatheter in the saphenous vein and analyzed using MATLAB. Mean arterial pressure (MAP) and central venous pressure (CVP) were continuously monitored. Cardiac output (CO), right ventricular diameter (RVd), and left ventricular end-diastolic area (LVEDA) were evaluated via transthoracic echocardiogram using the short axis left ventricular view. Dynamic markers such as pulse pressure variation (PPV) were calculated from the arterial waveform. The primary outcome was change in the first fundamental frequency (F1) of the venous waveform, which was assessed using analysis of variance (ANOVA). Mean F1 at each blood loss interval was compared to the mean at the subsequent interval. Additionally, the strength of the association between blood loss and F1 and each other marker was quantified using the marginal R2 in a linear mixed-effects model. RESULTS: PIVA derived mean F1 decreased significantly after hemorrhage of only 2% of the EBV, from 0.17 to 0.11 mm Hg, P = .001, 95% confidence interval (CI) of difference in means 0.02 to 0.10, and decreased significantly from the prior hemorrhage interval at 4%, 6%, 8%, 10%, and 12%. Log F1 demonstrated a marginal R2 value of 0.57 (95% CI 0.40-0.73), followed by PPV 0.41 (0.28-0.56) and CO 0.39 (0.26-0.58). MAP, LVEDA, and systolic pressure variation displayed R2 values of 0.31, and the remaining predictors had R2 values ≤0.2. The difference in log F1 R2 was not significant when compared to PPV 0.16 (95% CI -0.07 to 0.38), CO 0.18 (-0.06 to 0.04), or MAP 0.25 (-0.01 to 0.49) but was significant for the remaining markers. CONCLUSIONS: The mean F1 amplitude of PIVA was significantly associated with subclinical blood loss and most strongly associated with blood volume among the markers considered. This study demonstrates feasibility of a minimally invasive, low-cost method for monitoring perioperative blood loss.

High central venous pressure amplitude predicts successful defibrillation in a porcine model of cardiac arrest.

AIM: Increasing venous return during cardiopulmonary resuscitation (CPR) has been shown to improve hemodynamics during CPR and outcomes following cardiac arrest (CA). We hypothesized that a high central venous pressure amplitude (CVP-A), the difference between the maximum and minimum central venous pressure during chest compressions, could serve as a robust predictor of return of spontaneous circulation (ROSC) in addition to traditional measurements of coronary perfusion pressure (CPP) and end-tidal CO2 (etCO2) in a porcine model of CA. METHODS: After 10 min of ventricular fibrillation, 9 anesthetized and intubated female pigs received mechanical chest compressions with active compression/decompression (ACD) and an impedance threshold device (ITD). CPP, CVP-A and etCO2 were measured continuously. All groups received biphasic defibrillation (200 J) at minute 4 of CPR and were classified into two groups (ROSC, NO ROSC). Mean values were analyzed over 3 min before defibrillation by repeated-measures Analysis of Variance and receiver operating characteristic (ROC). RESULTS: Five animals out of 9 experienced ROSC. CVP-A showed a statistically significant difference (p = 0.003) between the two groups during 3 min of CPR before defibrillation compared to CPP (p = 0.056) and etCO2 (p = 0.064). Areas-under-the-curve in ROC analysis for CVP-A, CPP and etCO2 were 0.94 (95% Confidence Interval 0.86, 1.00), 0.74 (0.54, 0.95) and 0.78 (0.50, 1.00), respectively. CONCLUSION: In our study, CVP-A was a potentially useful predictor of successful defibrillation and return of spontaneous circulation. Overall, CVP-A could serve as a marker for prediction of ROSC with increased venous return and thereby monitoring the beneficial effects of ACD and ITD.

Large animal preclinical investigation into the optimal extracorporeal life support configuration for pulmonary hypertension and right ventricular failure.

INTRODUCTION: Right ventricular failure (RVF) is a major cause of mortality in pulmonary hypertension (PH). Mechanical circulatory support holds promise for patients with medically refractory PH, but there are no clinical devices for long-term right ventricular (RV) support. Investigations into optimal device parameters and circuit configurations for PH-induced RVF (PH-RVF) are needed. METHODS: Eleven sheep underwent previously published chronic PH model. We then evaluated a low-profile, ventricular assist device (VAD)-quality pump combined with a novel low-resistance membrane oxygenator (Pulmonary Assist Device, PAD) under one of four central cannulation strategies: right atrium-to-left atrium (RA-LA, N = 3), RA-to-pulmonary artery (RA-PA, N=3), pumpless pulmonary artery-to-left atrium (PA-LA, N = 2), and RA-to-ascending aorta (RA-Ao, N = 3). Acute-on-chronic RVF (AoC RVF) was induced, and mechanical support was provided for up to 6 hours at blood flow rates of 1 to 3 liter/min. Circuit parameters, physiologic, hemodynamic, and echocardiography data were collected. RESULTS: The RA-LA configuration achieved blood flow of 3 liter/min. Meanwhile, RA-PA and RA-Ao faced challenges maintaining 3 liter/min of flow due to higher circuit afterload. Pumpless PA-LA was flow-limited due to anatomical limitations inherent to this animal model. RA-LA and RA-Ao demonstrated serial RV unloading with increasing circuit flow, while RA-PA did not. RA-LA also improved left ventricular (LV) and septal geometry by echocardiographic assessment and had the lowest inotropic dependence. CONCLUSION: RA-LA and RA-Ao configurations unload the RV, while RA-LA also lowers pump speed and inotropic requirements, and improves LV mechanics. RA-PA provide inferior support for PH-RVF, while an alternate animal model is needed to evaluate PA-LA.

Venous waveform analysis detects acute right ventricular failure in a rat respiratory arrest model.

BACKGROUND: Peripheral intravenous analysis (PIVA) has been shown to be more sensitive than central venous pressure (CVP) for detecting hemorrhage and volume overload. We hypothesized that PIVA is superior to CVP for detecting right ventricular (RV) failure in a rat model of respiratory arrest. METHODS: Eight Wistar rats were studied in accordance with the ARRIVE guidelines. CVP, mean arterial pressure (MAP), and PIVA were recorded. Respiratory arrest was achieved with IV Rocuronium. PIVA utilizes Fourier transform to quantify the amplitude of the peripheral venous waveform, expressed as the "f1 amplitude". RV diameter was measured with transthoracic echocardiography. RESULTS: RV diameter increased from 0.34 to 0.54 cm during arrest, p = 0.001, and returned to 0.33 cm post arrest, p = 0.97. There was an increase in f1 amplitude from 0.07 to 0.38 mmHg, p = 0.01 and returned to 0.08 mmHg, p = 1.0. MAP decreased from 119 to 67 mmHg, p = 0.004 and returned to 136 mmHg, p = 0.50. There was no significant increase in CVP from 9.3 mmHg at baseline to 10.5 mmHg during respiratory arrest, p = 0.91, and recovery to 8.6 mmHg, p = 0.81. CONCLUSIONS: This study highlights the utility of PIVA to detect RV failure in small-caliber vessels, comparable to peripheral veins in the human pediatric population. IMPACT: Right ventricular failure remains a diagnostic challenge, particularly in pediatric patients with small vessel sizes limiting invasive intravascular monitor use. Intravenous analysis has shown promise in detecting hypovolemia and volume overload. Intravenous analysis successfully detects right ventricular failure in a rat respiratory arrest model. Intravenous analysis showed utility despite utilizing small peripheral venous access and therefore may be applicable to a pediatric population. Intravenous analysis may be helpful in differentiating various types of shock.

An Unusual Finding in a Patient Presenting for Pulmonary Thromboendarterectomy: Pulmonary Venous Thrombosis.

Pulmonary venous thrombosis (PVT) is a rare but potentially devastating disease state with a largely unknown incidence. The most common etiologies of PVT are secondary to complications of lung surgery, malignancy, catheter ablation for atrial fibrillation, and idiopathic causes. Diagnosis can be challenging because presenting symptoms often are vague and nonspecific, or even asymptomatic, and traditional diagnostic modalities, such as chest radiography and arterial phase computed tomography scans, are poor techniques for diagnosis. The authors present a case of a patient presenting for pulmonary thromboendarterectomy for a presumed diagnosis of chronic thromboembolic pulmonary hypertension who was found incidentally to have a PVT, on intraoperative transesophageal echocardiography. Due to significant thrombus burden, the new finding of PVT, and known association of PVT and malignancy, a biopsy of mediastinal lymph nodes was obtained, which revealed metastatic cervical carcinoma. The pulmonary endarterectomy procedure was aborted.

Venous Waveform Analysis Correlates With Echocardiography in Detecting Hypovolemia in a Rat Hemorrhage Model.

BACKGROUND: Assessing intravascular hypovolemia due to hemorrhage remains a clinical challenge. Central venous pressure (CVP) remains a commonly used monitor in surgical and intensive care settings for evaluating blood loss, despite well-described pitfalls of static pressure measurements. The authors investigated an alternative to CVP, intravenous waveform analysis (IVA) as a method for detecting blood loss and examined its correlation with echocardiography. METHODS: Seven anesthetized, spontaneously breathing male Sprague Dawley rats with right internal jugular central venous and femoral arterial catheters underwent hemorrhage. Mean arterial pressure (MAP), heart rate, CVP, and IVA were assessed and recorded. Hemorrhage was performed until each rat had 25% estimated blood volume removed. IVA was obtained using fast Fourier transform and the amplitude of the fundamental frequency (f1) was measured. Transthoracic echocardiography was performed utilizing a parasternal short axis image of the left ventricle during hemorrhage. MAP, CVP, and IVA were compared with blood removed and correlated with left ventricular end diastolic area (LVEDA). RESULTS: All 7 rats underwent successful hemorrhage. MAP and f1 peak amplitude obtained by IVA showed significant changes with hemorrhage. MAP and f1 peak amplitude also significantly correlated with LVEDA during hemorrhage (R = 0.82 and 0.77, respectively). CVP did not significantly change with hemorrhage, and there was no significant correlation between CVP and LVEDA. CONCLUSIONS: In this study, f1 peak amplitude obtained by IVA was superior to CVP for detecting acute, massive hemorrhage. In addition, f1 peak amplitude correlated well with LVEDA on echocardiography. Translated clinically, IVA might provide a viable alternative to CVP for detecting hemorrhage.

Anesthetic Considerations for Patients With Williams Syndrome.

Williams syndrome (WS) is a relatively rare congenital disorder which manifests across multiple organ systems with a wide spectrum of severity. Cardiovascular anomalies are the most common and concerning manifestations of WS, with supravalvar aortic stenosis present in up to 70% of patients with WS. Although a relatively rare disease, these patients frequently require sedation or anesthesia for a variety of medical procedures. The risk of sudden death in this population is 25 to 100 times that of the general population, with many documented deaths associated with sedation or anesthesia. This increased risk coupled with a disproportionately frequent need for anesthetic care renders it prudent for the anesthesiologist to have a firm understanding of the manifestations of WS. In the following review, the authors discuss pertinent clinical characteristics of WS along with particular anesthetic considerations for the anesthesiologist caring for patients with WS presenting for non-cardiac surgery.

Effect of Regional Analgesia Techniques on Opioid Consumption and Length of Stay After Thoracic Surgery.

BACKGROUND: We examined how intercostal nerve block (ICNB) with standard bupivacaine and ICNB with extended-release liposomal bupivacaine, compared with thoracic epidural analgesia (TEA), were associated with postoperative opioid pain medication consumption and hospital length of stay (LOS) after thoracic surgery. METHODS: We studied 1935 patients who underwent thoracic surgery between January 1, 2010, and November 30, 2017, at a tertiary academic center. Primary and secondary outcomes were postoperative opioid consumption expressed as morphine milligram equivalents (MMEs) at 24, 48, and 72 hours after surgery, the LOS, and total MME consumption from surgery to discharge. RESULTS: Of these patients, 888 (45.9%) received TEA, 730 (37.7%) ICNB with standard bupivacaine, 127 (6.6%) ICNB with liposomal bupivacaine, and 190 (9.8%) no regional analgesia. Compared with epidural analgesia, in 2017, ICNB liposomal bupivacaine provided similar pain control in terms of MME consumption at 24 and 72 hours, but decreased MME consumption at 48 hours (odds ratio [OR] = 0.33; confidence interval [CI] = 0.14-0.81) and at discharge (OR = 0.28; CI = 0.12-0.68) and was associated with a higher likelihood for a shorter LOS (hazard ratio = 3.46; CI = 2.42-4.96). Compared with TEA, ICNB with standard bupivacaine and no regional analgesia use showed varying impact on MME consumption between 24 and 72 hours after surgery, and their use was not associated with a significantly reduced MME consumption at discharge but with a shorter hospital LOS. CONCLUSIONS: Multimodal analgesia involving regional anesthetic alternatives to TEA could help manage postoperative pain in thoracic surgery patients.

A brief report on the effects of vasoactive agents on peripheral venous waveforms in a porcine model.

OBJECTIVES: Non-invasive venous waveform analysis (NIVA) is a recently described, novel technique to assess intravascular volume status. Waveforms are captured with a piezoelectric sensor; analysis in the frequency domain allows for calculation of a "NIVA value" that represents volume status. The aim of this report was to determine the effects of vasoactive agents on the venous waveform and calculated NIVA values. DESIGN: Porcine experimental model. SETTING: Operating theatre. PARTICIPANTS: A piezoelectric sensor was secured over the surgically exposed saphenous vein in eight anesthetized pigs. MAIN OUTCOME MEASURES: NIVA value, pulmonary capillary wedge pressure (PCWP), and mean arterial pressure prior to and post intravenous administration of 150-180 µg of phenylephrine or 100 µg of sodium nitroprusside. RESULTS: Phenylephrine led to a decrease in NIVA value (mean 9.2 vs. 4.6, p < 0.05), while sodium nitroprusside led to an increase in NIVA value (mean 9.5 vs. 11.9, p < 0.05). Mean arterial pressure increased after phenylephrine (p < 0.05) and decreased after sodium nitroprusside (p < 0.05). PCWP did not change significantly after phenylephrine (p = 0.25) or sodium nitroprusside (p = 0.06). CONCLUSIONS: Vasoactive agents lead to changes in non-invasively obtained venous waveforms in euvolemic pigs, highlighting a potential limitation in the ability to NIVA to estimate static volume in this setting. Further studies are indicated to understand the effects of vasoactive agents in the setting of hypovolemia and hypervolemia.

Severe Cardiopulmonary Disease in a Parturient With Noonan Syndrome.

Noonan syndrome is a relatively common genetic disorder and the second most common cause of congenital heart disease after trisomy 21. The spectrum of cardiac anomalies in Noonan syndrome typically involves pulmonary valve stenosis occasionally in conjunction with hypertrophic cardiomyopathy. Mitral valve involvement is a rare finding in Noonan syndrome and is most commonly associated with either mitral valve prolapse or abnormal valvular insertion causing left ventricular outflow tract obstruction. Patients with Noonan syndrome typically have preserved fertility and, given the success of cardiac surgery and medical management of heart failure in this population, are beginning to present more commonly as parturients in adulthood. Maternal physiologic changes during pregnancy introduce an added complexity to hemodynamic management and anesthetic considerations during labor and delivery. In this article, we present a case of a patient with Noonan syndrome with severe mitral stenosis, pulmonary valve insufficiency, and severe restrictive and obstructive pulmonary disease who presented preterm for delivery due to increased dyspnea at rest. Here we review the pathophysiology behind Noonan syndrome and peripartum management strategies in a patient with severe combined cardiac and pulmonary disease.

Non-Invasive Venous waveform Analysis (NIVA) for volume assessment during complex cranial vault reconstruction: A proof-of-concept study in children.

BACKGROUND: Non-Invasive Venous waveform Analysis (NIVA) is novel technology that captures and analyzes changes in venous waveforms from a piezoelectric sensor on the wrist for hemodynamic volume assessment. Complex cranial vault reconstruction is performed in children with craniosynostosis and is associated with extensive blood loss, potential life-threatening risks, and significant morbidity. In this preliminary study, we hypothesized that NIVA will provide a reliable, non-invasive, quantitative assessment of intravascular volume changes in children undergoing complex cranial vault reconstruction. OBJECTIVE: To present proof-of-concept results of a novel technology in the pediatric population. METHODS: The NIVA prototype was placed on each subject's wrist, and venous waveforms were collected intraoperatively. Estimated blood loss and fluid/blood product administration were recorded in real time. Venous waveforms were analyzed into a NIVA value and then correlated, along with mean arterial pressure (MAP), to volume changes. Concordance was quantified to determine if the direction of change in volume was similar to the direction of change in MAP or change in NIVA. RESULTS: Of 18 patients enrolled, 14 had usable venous waveforms, and there was a significant correlation between change in NIVA value and change in volume. Change in MAP did not correlate with change in volume. The concordance between change in MAP and change in volume was less than the concordance between change in NIVA and change in volume. CONCLUSION: NIVA values correlate more closely to intravascular volume changes in pediatric craniofacial patients than MAP. This initial study suggests that NIVA is a potential safe, reliable, non-invasive quantitative method of measuring intravascular volume changes for children undergoing surgery.

Non-invasive venous waveform analysis (NIVA) for volume assessment in patients undergoing hemodialysis: an observational study.

BACKGROUND: Accurate assessment of volume status to direct dialysis remains a clinical challenge. Despite current attempts at volume-directed dialysis, inadequate dialysis and intradialytic hypotension (IDH) are common occurrences. Peripheral venous waveform analysis has recently been developed as a method to accurately determine intravascular volume status through algorithmic quantification of changes in the waveform that occur at different volume states. A noninvasive method to capture peripheral venous signals is described (Non-Invasive Venous waveform Analysis, NIVA). The objective of this proof-of-concept study was to characterize changes in NIVA signal with dialysis. We hypothesized that there would be a change in signal after dialysis and that the rate of intradialytic change in signal would be predictive of IDH. METHODS: Fifty subjects undergoing inpatient hemodialysis were enrolled. A 10-mm piezoelectric sensor was secured to the middle volar aspect of the wrist on the extremity opposite to the access site. Signals were obtained fifteen minutes before, throughout, and up to fifteen minutes after hemodialysis. Waveforms were analyzed after a fast Fourier transformation and identification of the frequencies corresponding to the cardiac rate, with a NIVA value generated based on the weighted powers of these frequencies. RESULTS: Adequate quality (signal to noise ratio > 20) signals pre- and post- dialysis were obtained in 38 patients (76%). NIVA values were significantly lower at the end of dialysis compared to pre-dialysis levels (1.203 vs 0.868, p < 0.05, n = 38). Only 16 patients had adequate signals for analysis throughout dialysis, but in this small cohort the rate of change in NIVA value was predictive of IDH with a sensitivity of 80% and specificity of 100%. CONCLUSIONS: This observational, proof-of-concept study using a NIVA prototype device suggests that NIVA represents a novel and non-invasive technique that with further development and improvements in signal quality may provide static and continuous measures of volume status to assist with volume directed dialysis and prevent intradialytic hypotension.