Arterial and central venous pressure monitoring

Changes in Intra-Amniotic, Fetal Intrathoracic, and Intraperitoneal Pressures with Uterine Contraction: A Report of Three Cases

Intra-amniotic, fetal intrathoracic, and intraperitoneal pressures during pregnancy have been previously investigated. However, to our knowledge, changes in these pressures during uterine contractions have not been reported. Herein, we present three cases of polyhydramnios, fetal pleural effusion, and fetal ascites, in which intra-amniotic, fetal intrathoracic, intraperitoneal pressures increased with uterine contractions. These pressure increases may affect the fetal circulation. We suggest that managing potential premature delivery (e.g., with tocolysis) is important in cases with polyhydramnios and excess fluid in fetal body areas, such as the thorax, abdomen, and heart. The results of this preliminary study on intrafetal pressure measurements will be useful in performing fetal and neonatal surgeries in the future.

Needle-guided ultrasound technique for axillary artery catheter placement in critically ill patients: A case series and technique description

PURPOSE

Axillary arterial cannulation for blood pressure monitoring has been reported in adults since 1973. Reported failure rates using palpation landmarks are high. This report describes a needle-guided ultrasound technique for axillary arterial line placement in critically ill patients.

METHODS

A retrospective review of all patients requiring axillary arterial cannulation attempts with ultrasound-assisted needle guidance for hemodynamic monitoring was performed from July 2010 to June 2016 at a single institution.

RESULTS

One hundred fifty nine (159) cannulation attempts were performed in 155 patients. The overall success rate was 97%, with a first pass success rate of 84%. Inexperienced operators performed 49% of procedures under direct faculty supervision, and had a 99% success rate, which was not different from experienced operators. Almost 20% of patients had moderate-to-severe coagulopathy (platelets<50k/uL, INR>2.0 or PTT>60s). Complications reported included the following: nonfunctioning of catheter (6%) and hematoma (6%). Ischemia was noted in 2 patients (1%), but only one was attributed to the arterial catheter.

CONCLUSIONS

Use of the needle-guided ultrasound assisted approach for axillary arterial line placement is easily teachable and can be used to promote safe and successful placement of axillary arterial lines for novice learners.

A Review of Central Venous Pressure and Its Reliability as a Hemodynamic Monitoring Tool in Veterinary Medicine

OBJECTIVE

To review the current literature regarding central venous pressure (CVP) in veterinary patients pertaining to placement (of central line), measurement, interpretation, use in veterinary medicine, limitations, and controversies in human medicine.

ETIOLOGY

CVP use in human medicine is a widely debated topic, as numerous sources have shown poor correlation of CVP measurements to the volume status of a patient. Owing to the ease of placement and monitoring in veterinary medicine, CVP remains a widely used modality for evaluating the hemodynamic status of a patient. A thorough evaluation of the veterinary and human literature should be performed to evaluate the role of CVP measurements in assessing volume status in veterinary patients.

DIAGNOSIS

Veterinary patients that benefit from accurate CVP readings include those suffering from hypovolemic or septic shock, heart disease, or renal disease or all of these. Other patients that may benefit from CVP monitoring include high-risk anesthetic patients undergoing major surgery, trending of fluid volume status in critically ill patients, patients with continued shock, and patients that require rapid or large amounts of fluids.

THERAPY

The goal of CVP use is to better understand a patient's intravascular volume status, which would allow early goal-directed therapy.

PROGNOSIS

CVP would most likely continue to play an important role in the hemodynamic monitoring of the critically ill veterinary patient; however, when available, cardiac output methods should be considered the first choice for hemodynamic monitoring.

Using what you get: dynamic physiologic signatures of critical illness

The development and resolution of cardiopulmonary instability take time to become clinically apparent, and the treatments provided take time to have an impact. The characterization of dynamic changes in hemodynamic and metabolic variables is implicit in physiologic signatures. When primary variables are collected with high enough frequency to derive new variables, this data hierarchy can be used to develop physiologic signatures. The creation of physiologic signatures requires no new information; additional knowledge is extracted from data that already exist. It is possible to create physiologic signatures for each stage in the process of clinical decompensation and recovery to improve outcomes.

Goal-directed therapy in small animal critical illness

Monitoring critically ill patients can be a daunting task even for experienced clinicians. Goal-directed therapy is a technique involving intensive monitoring and aggressive management of hemodynamics in patients with high risk of morbidity and mortality. The aim of goal-directed therapy is to ensure adequate tissue oxygenation and survival. This article reviews commonly used diagnostics in critical care medicine and what the information gathered signifies and discusses clinical decision making on the basis of diagnostic test results. One example is early goal-directed therapy for severe sepsis and septic shock. The components and application of goals in early goal-directed therapy are discussed.

Taking the septic patient to the operating room

The acutely septic patient is a multifaceted challenge for the anesthetist. Unlike most elective surgery patients, acutely septic patients have severe systemic disease before the physiologic insults of anesthesia and surgery. The decision to operate is usually informed by the urgent or emergent need to correct a severe surgical problem and weighed against the higher risks of morbidity and mortality from the procedure itself. The care of the septic patient in the intensive care unit can help guide operating room management. However, the acuity and time course of intraoperative events, including hemorrhage and drug-induced shock states, compel the anesthetist to respond aggressively with therapies that may or may not be strongly substantiated with long-term data in the intensive care unit setting. The anesthesiologist must place considerations concerning short-term survival from the acute insult of surgery ahead of longer-term considerations.

Is external jugular venous pressure a good predictor of volume status in kidney graft recipients?

To ensure appropriate function of the transplanted organ, it is necessary to adequately maintain vascular volume during the kidney transplantation procedure. For this purpose, central venous pressure (CVP) is monitored through a catheter inserted into the superior vena cava (SVC). Central venous cannulation is associated with a risk of serious complications. An objective of this study was to investigate whether there was a correlation between pressures measured in the SVC and in the external jugular vein (EJV). We studied 33 chronically dialyzed patients who had a short catheter placed in the EJV because of difficulties in peripheral vein cannulation in the limbs. In each case, general anesthesia was induced and a central catheter inserted into the SVC. Every 10 minutes venous pressure measurements were obtained simultaneously at both sites. A significant (P < .001) correlation was observed between external jugular vein pressure (EJVP) and CVP. CVP could be described as a function of EJVP by the equation CVP = {0.90299 x EJVP} - 0.8361. The results of this study indicated that monitoring the EJVP allows equally efficient evaluation of vascular volume as the CVP. In our opinion, EJVP is sufficient to evaluate vascular volume during kidney transplantation in patients with difficult vascular access.

Development of a new semi-quantitative non-invasive method for evaluating ventricular stroke work

BACKGROUND AND AIM

Ventricular stroke work (SW) is one of the best indices to evaluate ventricular function, however, the SW monitoring mainly depends on the invasive method with the artery catheter. In this paper, our aim is to develop a new semi-quantitative non-invasive method for evaluating ventricular SW.

METHODS

The multiple gated cardiac blood pool imaging was done in 25 patients with coronary artery disease and 12 normal controls. A new parameter, the relative stroke work (RSW) of left ventricle, was calculated using an equation derived from the principle of hydrodynamics. The left ventricular SW was analyzed by stroke volume (SV) and mean arterial pressure. Ejected fraction (EF), peak ejected rate (PER) and peak filling rate (PFR) were gotten with the routine software in imaging device.

RESULTS

The left ventricular RSW was linearly correlated with the SW. The RSW was related to the SV, EF, PER and PFR of the left ventricle. The RSW had regressive relation with SV and PER. The RSW in patients, same as SW, SV, EF, PFR and PER, was noticeably lower than that in normal controls, P<0.01.

CONCLUSION

The RSW is a potential and valuable clinical index for evaluation of the ventricular function.

Influence of hypercapnic vasodilation on cerebrovascular autoregulation and pial arteriolar bed resistance in piglets

Changes in both pial arteriolar resistance (PAR) and simulated arterial-arteriolar bed resistance (SimR) of a physiologically based biomechanical model of cerebrovascular pressure transmission, the dynamic relationship between arterial blood pressure and intracranial pressure, are used to test the hypothesis that hypercapnia disrupts autoregulatory reactivity. To evaluate pressure reactivity, vasopressin-induced acute hypertension was administered to normocapnic and hypercapnic (N = 12) piglets equipped with closed cranial windows. Pial arteriolar diameters were used to compute arteriolar resistance. Percent change of PAR (%DeltaPAR) and percent change of SimR (%DeltaSimR) in response to vasopressin-induced acute hypertension were computed and compared. Hypercapnia decreased cerebrovascular resistance. Indicative of active autoregulatory reactivity, vasopressin-induced hypertensive challenge resulted in an increase of both %DeltaPAR and %DeltaSimR for all normocapnic piglets. The hypercapnic piglets formed two statistically distinct populations. One-half of the hypercapnic piglets demonstrated a measured decrease of both %DeltaPAR and %DeltaSimR to pressure challenge, indicative of being pressure passive, whereas the other one-half demonstrated an increase in these percentages, indicative of active autoregulation. No other differences in measured variables were detectable between regulating and pressure-passive piglets. Changes in resistance calculated from using the model mirrored those calculated from arteriolar diameter measurements. In conclusion, vasodilation induced by hypercapnia has the potential to disrupt autoregulatory reactivity. Our physiologically based biomechanical model of cerebrovascular pressure transmission accurately estimates the changes in arteriolar resistance during conditions of active and passive cerebrovascular reactivity.