Advanced airway management and respiratory care in decompensated pulmonary hypertension.

Meticulous risk stratification is essential when considering intubation of a patient with decompensated pulmonary hypertension (dPH). It is paramount to understand both the pathophysiology of dPH (and associated right ventricular failure) and the complications related to a high-risk intubation before attempting the procedure. There are few recommendations in this area and the literature, guiding these recommendations, is limited to expert opinion and very few case reports/case series. This review will discuss the complex pathophysiology of dPH, the complications associated with intubation, the debates surrounding induction agents, and the available options for the intubation procedure, with specific emphasis on the emerging role for awake fiberoptic intubation. All patients should be evaluated for candidacy for veno-arterial extracorporeal membrane oxygen as a bridge to recovery, lung transplantation, or pulmonary endarterectomy prior to intubation. Only an experienced proceduralist who is both comfortable with high-risk intubations and the pathophysiology of dPH should perform these intubations.

Diagnostic Point-of-Care Ultrasound: Recommendations From an Expert Panel.

Diagnostic point-of-care ultrasound (PoCUS) has emerged as a powerful tool to help anesthesiologists guide patient care in both the perioperative setting and the subspecialty arenas. Although anesthesiologists can turn to guideline statements pertaining to other aspects of ultrasound use, to date there remains little in the way of published guidance regarding diagnostic PoCUS. To this end, in 2018, the American Society of Anesthesiologists chartered an ad hoc committee consisting of 23 American Society of Anesthesiologists members to provide recommendations on this topic. The ad hoc committee convened and developed a committee work product. This work product was updated in 2021 by an expert panel of the ad hoc committee to produce the document presented herein. The document, which represents the consensus opinion of a group of practicing anesthesiologists with established expertise in diagnostic ultrasound, addresses the following issues: (1) affirms the practice of diagnostic PoCUS by adequately trained anesthesiologists, (2) identifies the scope of practice of diagnostic PoCUS relevant to anesthesiologists, (3) suggests the minimum level of training needed to achieve competence, (4) provides recommendations for how diagnostic PoCUS can be used safely and ethically, and (5) provides broad guidance about diagnostic ultrasound billing.

Echocardiography-Guided Dual-Lumen Venovenous Extracorporeal Membrane Oxygenation Cannula Placement in the ICU-A Retrospective Review.

OBJECTIVE: The most effective method of image guidance for venovenous extracorporeal membrane oxygenation is not known. The authors' objectives were to define the frequency of successful initial cannulation using echocardiographic guidance in the intensive care unit, as well as to determine the frequency of subsequent adjustments. Additional aims were to illustrate cannula malposition problems and to describe features associated with difficult cannulation. DESIGN: Retrospective consecutive case series analysis. SETTING: Single tertiary care university hospital. PARTICIPANTS: Forty-five patients treated with venovenous extracorporeal membrane oxygenation. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The most common causes of respiratory failure were pneumonia, aspiration, and inhalational burn injury. Sixty-two percent survived to discharge. Initial cannulation was successful in 39 cases (87%). Adverse events included 5 cases of cannula malposition and 1 case of hemorrhagic shock. During the course of extracorporeal membrane oxygenation, 17 patients (38%) required echo-guided cannula position adjustments. There were no fatal complications. Factors associated with difficult cannulation included extremes of size, a prominent Eustachian valve, and an anterior guidewire bending in the right atrium. Younger age was associated positively with survival. There was no significant association between adverse events during cannulation and survival. CONCLUSIONS: Dual-lumen venovenous extracorporeal membrane oxygenation cannulation in the intensive care unit under echo guidance has a high initial success rate, but many patients require subsequent repositioning. Echocardiography can define cannula position in sufficient detail to identify malposition precisely and to guide repositioning.

A review of 364 perioperative rescue echocardiograms: findings of an anesthesiologist-staffed perioperative echocardiography service.

OBJECTIVE: Review the findings and use of rescue echocardiography performed by the Division of Perioperative Echocardiography and its impact on patient management. DESIGN: Retrospective observational study. SETTING: Single institution, tertiary care hospital. PARTICIPANTS: Three hundred sixty-four consecutive rescue echocardiograms in the perioperative setting. INTERVENTIONS: Rescue transesophageal or rescue transthoracic echocardiography. MEASUREMENTS AND MAIN RESULTS: Of a total of 1,675 perioperative echocardiograms performed in a 28-month period, 364 (21.8%) were rescue studies. Of these, 95.9% were transesophageal and 4.1% were transthoracic. Location at time of rescue echocardiography was intraoperative (55.5%), postoperative (44.2%), and preoperative (0.3%). No single diagnosis predominated the intraoperative or postoperative environment, and the frequency of common etiologies did not allow for assumption. There was a change in management for 214 patients (59%) as the result of findings. The methods used in performing rescue echocardiography at the authors' institution are reported. CONCLUSIONS: The heterogeneity of diagnoses and the frequency with which rescue echocardiography changed management further supports the growing body of evidence that the hemodynamically unstable perioperative patient benefits from its use.

The bed nucleus of the stria terminalis is required for the expression of contextual but not auditory freezing in rats with basolateral amygdala lesions.

Previous data suggest that overtraining can overcome fear conditioning deficits in rats with lesions of the basolateral complex of the amygdala (BLA). We have previously shown that the central nucleus of the amygdala (CEA) is essential for the acquisition and expression of conditional fear to both contextual and auditory conditioned stimuli (CSs) after overtraining. This provides strong evidence that the CEA can compensate for the loss of the BLA. Another brain area that may compensate for the loss of the BLA is the bed nucleus of the stria terminalis (BNST). We explored this possibility by examining the consequences of lesions or reversible inactivation of the BNST on the expression of overtrained fear in rats with BLA lesions. We demonstrate that lesions or inactivation of the BNST block the expression of freezing to the conditioning context, but not to an auditory conditional stimulus. These results reveal that the BNST has a critical role in the expression of contextual fear, but not fear to an auditory CS, and is therefore not the essential locus of compensation for fear learning in the absence of the BLA.

PKMzeta maintains spatial, instrumental, and classically conditioned long-term memories.

How long-term memories are stored is a fundamental question in neuroscience. The first molecular mechanism for long-term memory storage in the brain was recently identified as the persistent action of protein kinase Mzeta (PKMzeta), an autonomously active atypical protein kinase C (PKC) isoform critical for the maintenance of long-term potentiation (LTP). PKMzeta maintains aversively conditioned associations, but what general form of information the kinase encodes in the brain is unknown. We first confirmed the specificity of the action of zeta inhibitory peptide (ZIP) by disrupting long-term memory for active place avoidance with chelerythrine, a second inhibitor of PKMzeta activity. We then examined, using ZIP, the effect of PKMzeta inhibition in dorsal hippocampus (DH) and basolateral amygdala (BLA) on retention of 1-d-old information acquired in the radial arm maze, water maze, inhibitory avoidance, and contextual and cued fear conditioning paradigms. In the DH, PKMzeta inhibition selectively disrupted retention of information for spatial reference, but not spatial working memory in the radial arm maze, and precise, but not coarse spatial information in the water maze. Thus retention of accurate spatial, but not procedural and contextual information required PKMzeta activity. Similarly, PKMzeta inhibition in the hippocampus did not affect contextual information after fear conditioning. In contrast, PKMzeta inhibition in the BLA impaired retention of classical conditioned stimulus-unconditioned stimulus (CS-US) associations for both contextual and auditory fear, as well as instrumentally conditioned inhibitory avoidance. PKMzeta inhibition had no effect on postshock freezing, indicating fear expression mediated by the BLA remained intact. Thus, persistent PKMzeta activity is a general mechanism for both appetitively and aversively motivated retention of specific, accurate learned information, but is not required for processing contextual, imprecise, or procedural information.

NMDA receptor antagonism in the basolateral but not central amygdala blocks the extinction of Pavlovian fear conditioning in rats.

Glutamate receptors in the basolateral complex of the amygdala (BLA) are essential for the acquisition, expression and extinction of Pavlovian fear conditioning in rats. Recent work has revealed that glutamate receptors in the central nucleus of the amygdala (CEA) are also involved in the acquisition of conditional fear, but it is not known whether they play a role in fear extinction. Here we examine this issue by infusing glutamate receptor antagonists into the BLA or CEA prior to the extinction of fear to an auditory conditioned stimulus (CS) in rats. Infusion of the alpha-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) receptor antagonist, 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX), into either the CEA or BLA impaired the expression of conditioned freezing to the auditory CS, but did not impair the formation of a long-term extinction memory to that CS. In contrast, infusion of the N-methyl-D-aspartate (NMDA) receptor antagonist, D,L-2-amino-5-phosphonopentanoic acid (APV), into the amygdala, spared the expression of fear to the CS during extinction training, but impaired the acquisition of a long-term extinction memory. Importantly, only APV infusions into the BLA impaired extinction memory. These results reveal that AMPA and NMDA receptors within the amygdala make dissociable contributions to the expression and extinction of conditioned fear, respectively. Moreover, they indicate that NMDA receptor-dependent processes involved in extinction learning are localized to the BLA. Together with previous work, these results reveal that NMDA receptors in the CEA have a selective role acquisition of fear memory.

The amygdala is not necessary for unconditioned stimulus inflation after Pavlovian fear conditioning in rats.

The basolateral complex (BLA) and central nucleus (CEA) of the amygdala play critical roles in associative learning, including Pavlovian conditioning. However, the precise role for these structures in Pavlovian conditioning is not clear. Recent work in appetitive conditioning paradigms suggests that the amygdala, particularly the BLA, has an important role in representing the value of the unconditioned stimulus (US). It is not known whether the amygdala performs such a function in aversive paradigms, such as Pavlovian fear conditioning in rats. To address this issue, Experiments 1 and 2 used temporary pharmacological inactivation of the amygdala prior to a US inflation procedure to assess its role in revaluing shock USs after either overtraining (Experiment 1) or limited training (Experiment 2), respectively. Inactivation of the BLA or CEA during the inflation session did not affect subsequent increases in conditioned freezing observed to either the tone conditioned stimulus (CS) or the conditioning context in either experiment. In Experiment 3, NBQX infusions into the BLA impaired the acquisition of auditory fear conditioning with an inflation-magnitude US, indicating that the amygdala is required for associative learning with intense USs. Together, these results suggest that the amygdala is not required for revaluing an aversive US despite being required for the acquisition of fear to that US.

The central nucleus of the amygdala is essential for acquiring and expressing conditional fear after overtraining.

The basolateral complex of the amygdala (BLA) is critical for the acquisition and expression of Pavlovian fear conditioning in rats. Nonetheless, rats with neurotoxic BLA lesions can acquire conditional fear after overtraining (75 trials). The capacity of rats with BLA lesions to acquire fear memory may be mediated by the central nucleus of the amygdala (CEA). To examine this issue, we examined the influence of neurotoxic CEA lesions or reversible inactivation of the CEA on the acquisition and expression of conditional freezing after overtraining in rats. Rats with pretraining CEA lesions (whether alone or in combination with BLA lesions) did not acquire conditional freezing to either the conditioning context or an auditory conditional stimulus after extensive overtraining. Similarly, post-training lesions of the CEA or BLA prevented the expression of overtrained fear. Lastly, muscimol infusions into the CEA prevented both the acquisition and the expression of overtrained fear, demonstrating that the effects of CEA lesions are not likely due to the destruction of en passant axons. These results suggest that the CEA is essential for conditional freezing after Pavlovian fear conditioning. Moreover, overtraining may engage a compensatory fear conditioning circuit involving the CEA in animals with damage to the BLA.

The Effect of Perioperative Rescue Transesophageal Echocardiography on the Management of Trauma Patients.

To evaluate the effect of rescue transesophageal echocardiography (TEE) on the management of trauma patients, we reviewed imaging and charts of unstable trauma patients at a level I trauma center. Critical rescue TEE findings included acute right ventricular failure, stress cardiomyopathy, type B aortic dissection, mediastinal air, and dynamic left ventricular outflow tract obstruction. Left ventricular filling was classified as low (underfilled) in 57% of all cases. Rescue TEE revealed a variety of new diagnoses and led to a change in resuscitation strategy about half of the time.

Fear extinction in rodents.

Pavlovian conditioning paradigms have become important model systems for understanding the neuroscience of behavior. In particular, studies of the extinction of Pavlovian fear responses are yielding important information about the neural substrates of anxiety disorders, such as phobias and post-traumatic stress disorder (PTSD) in humans. These studies are germane to understanding the neural mechanisms underlying behavioral interventions that suppress fear, including exposure therapy in anxiety disorders. This unit describes detailed behavioral protocols for examining the nature and properties of fear extinction in laboratory rodents.

Perioperative echocardiography: two-dimensional and three-dimensional applications.

Perioperative echocardiography is an essential skill for today's cardiac anesthesiologist and a driving force for innovation and accomplishment for the future of the subspecialty. Real-time three-dimensional transesophageal echocardiography (RT3-D TEE) will dominate the future practice of perioperative echocardiography, but transthoracic echocardiography (TTE) will grow in application, as will contrast echocardiography. Hand-held ultrasonongraphs will rival current machines in capabilities and make it possible for TTE to become the stethoscope of the future for cardiac anesthesiologists.