Mario Concha

Pulse contour analysis and transesophageal echocardiography: a comparison of measurements of cardiac output during laparoscopic colon surgery.

BACKGROUND: Pulse wave analysis (PWA) allows cardiac output (CO) measurement after calibration by transpulmonary thermodilution. A PWA system that does not require previous calibration, the FloTrac/Vigileo (FTV), has been recently developed. We compared determinations of CO made with the FTV to simultaneous measurements using transesophageal echocardiography (TEE). METHOD: Ten ASA I-II patients scheduled for laparoscopic colorectal surgery were studied. A radial 20-gauge cannula was inserted and connected to a hemodynamic monitor and a FTV system for PWA and determination of CO (COPWA). TEE CO (COTEE) was determined as previously described. Measurements were made after intubation, 5 min after establishing the lithotomy position, 5 min after establishing pneumoperitoneum, every 30 min, or each time mean arterial blood pressure decreased below basal values. Statistical analysis was made with the Bland and Altman method. RESULTS: Eighty-eight measurements were compared. The COTEE values ranged from 3.23 to 12 Lt/min (mean 6.21 ± 1.85). Values for COPWA ranged from 2.9 to 8.5 Lt/min (mean 4.84 ± 1.14). Bias was 1.17 and limits of agreement −2.02 and 4.37. The percentage error between all COTEE and COPWA measurements was 40% (27%-50%) mean (range). CONCLUSION: During laparoscopic colon surgery, clinically important differences were observed between CO determinations made with TEE and FTV.

The Volume of Lactated Ringer's Solution Required to Maintain Preload and Cardiac Index During Open and Laparoscopic Surgery

BACKGROUND: Recent studies have emphasized the importance of perioperative fluid restriction. However, fluid restriction regimens may increase the likelihood of insufficient perioperative fluid administration or may result in excess intravascular crystalloid replacement. We postulate that the use of transesophageal echocardiography may reduce the amount of crystalloid administered during open and laparoscopic colorectal surgery. METHODS: Fifteen ASA I and II patients scheduled for open colorectal surgery, and 15 patients scheduled for laparoscopic surgery were studied. Lactated Ringers solution was infused during the procedures. Left ventricular end diastolic volume index (LVEDVI) and cardiac index were assessed throughout surgery and used to guide the rate of lactated Ringers solution administration. Statistical analysis was performed with Students t-test for unpaired samples. RESULTS: The rate of crystalloid administration required to maintain baseline LVEDVI and cardiac index was 5.9 ± 2 mL · kg−1 · h−1 for open surgery and 3.4 ± 0.8 mL · kg−1 · h−1 for laparoscopic surgery (P < 0.01). This slower rate for laparoscopic surgery was offset by the longer surgical duration. CONCLUSION: The rate of crystalloid solution to maintain baseline LVEDVI and cardiac index was greater in open surgery than laparoscopic surgery, and lower than commonly recommended for colorectal surgery.

Propofol concentration to induce general anesthesia in children aged 3–11 years with the Kataria effect-site model

The propofol pharmacokinetic model derived by Kataria et al. was recently modified to perform effect‐site target‐controlled infusion (TCI). Effect‐site concentration (Ce) targets to induce general anesthesia with this model in children have not been described. The aim of this study was to identify propofol Ce targets associated with success rates of 50% (Ce50) and 95% (Ce95) among children 3–11 years of age.

Continuous Erector Spinae Plane block for thoracic surgery in a pediatric patient

Sir—Pediatric regional anesthesia has been gaining popularity since the introduction of ultrasound techniques, adding precision and new blocks. One newly described ultrasound-guided block in the adult population is the Erector Spinae Plane (ESP) block. It is a facial plane block where local anesthetic is injected between the erector spinae muscle and the underlying transverse process, and was initially described at the T5 level for costal pain and thoracic surgery. There is a recent report of a single shot ESP block on a 7-yearold child. We would like to report the use of a continuous ESP block in a 3-year-old, 13 kg male patient for postoperative pain after open thoracotomy. The patient was a full-term newborn, with a hypoplastic left heart syndrome. He already had several surgeries for his cardiac defect. A postsurgical diaphragmatic paralysis after a Fontan procedure was diagnosed and surgical treatment was indicated. A thoracoscopic diaphragm plication attempt was unsuccessful and open thoracotomy surgery was then scheduled. Balanced general anesthesia was given. Standard monitoring was placed and a radial arterial line was inserted. Sevoflurane, fentanyl boluses, and neuromuscular blocker were used. At the end of surgery, at the surgical incision level (T9), an ESP block was done with the patient still lying on his left side. A 6-13 MHz linear probe was used (SonoSite Edge; SonoSite, Inc., Bothell, WA, USA). After skin cleaning, using a right sagittal paramedian probe orientation, transverse processes were identified. A 5 cm 20G Tuohy needle was inserted in-plane, caudal-cranial direction until the tip of the transverse process was contacted (Figure 1). After negative aspiration, 8 mL of 0.25% levo-bupivacaine (Chirocaine 5 mg/mL; Abbvie, Elverum, Norway) was injected. Immediately after injection, a 22G epidural catheter was threaded 2 cm beyond the needle, fixed to the skin and covered with a transparent dressing. The patient was extubated and transferred to the pediatric intensive care unit. At PICU arrival, the patient was awake, breathing smoothly, stable vital signs, and 0/10 point CHIPPS score was measured. Two hours later, a PCA pump with 0.1% levo-bupivacaine 3 mL/h continuous infusion was started. A 1.5 mL rescue bolus, 30-minute lockout, was programmed (to be used by a nurse or parent caring for the child). Scheduled oral acetaminophen and intravenous ketorolac were prescribed. On the 4th postoperative day, after chest tubes were removed, the local anesthetic infusion was stopped and the catheter was removed. During the postoperative period, only twice was a PCA bolus given. No other rescue medication was needed. The child never complained about pain and easily allowed chest physiotherapy, SpO2 ranging from 80% to 90% (considered adequate for his cardiac pathology). Open thoracic surgery is considered a very painful procedure, and thoracic epidural analgesia has been widely used with excellent results. In this patient, an alternative to epidural analgesia was sought, because of the unknown effects of his chronic heart condition on epidural vessels. We believe, ESP block will become a useful tool in regional anesthesia, potentially replacing epidural analgesia in many conditions. Obviously, prospective randomized controlled trials comparing ESP block with current standard analgesic techniques are needed.

Transesophageal echocardiography during noncardiac pediatric surgery

rial by Sneyd and O’Sullivan, it is crucially important to clarify the motivation for choosing a particular approach to facilitate endotracheal intubation (2). While the practice of nonrelaxant intubation in children appears to be rather common, valid alternatives to nonrelaxant approaches exist in virtually all but the shortest cases that customarily require tracheal intubation such as adenotonsillectomies. The available data, as recently reviewed by Aouad et al. (3), suggest that relaxant-free intubation strategies have not been found to provide better intubating conditions than relaxant techniques in direct comparisons. A carefully conducted trial in an adult population by Mencke et al. (4) further demonstrated that the quality of intubating conditions was a significant contributor to laryngeal morbidity and that ‘good’ and ‘excellent’ intubation conditions were not equivalent in terms of risk of injury. While no such data exist in the pediatric population, I fear the concern over a similar relationship is not misplaced. Therefore, any further scientific inquiry into methods of relaxant-free intubation should clearly explain the rationale for pursuing such a technique in terms of expected benefit to the patient and in terms of potential risk of airway morbidity from suboptimal intubating conditions.

Systolic anterior motion(SAM): una causa infrecuente de hipotensión severa en el perioperatorio de cirugía no cardiaca

Background: Systolic anterior motion describes the anterior displacement of one or both mitral valve leaflets, obstructing the outflow tract of the left ventricle. It can be a cause of severe hypotension during the intraoperative and postoperative period of non-cardiac surgery. The diagnosis is made with echocardiography. We report two patients with this problem. The first was a 74-year-old male subjected to an incisional hernia repair who presented severe hypotension in the intraoperative period. A transesophageal echocardiography revealed an anterior displacement of the mitral valve anterior leaflet. Epinephrine was discontinued and Norepinephrine and a volume expander were administered, with good response. The second patient was a 64-year-old male undergoing a right liver lobectomy. In the postoperative period, he suffered severe hypotension. A transesophageal echocardiography revealed an anterior displacement of the mitral valve anterior leaflet. Dobutamine was discontinued, volume was administered, and a Norepinephrine infusion was started with good response.

Single-lung ventilation for resection of a giant bronchogenic cyst in a 5-month-old patient

SLV in children has been limited by the lack of small double lumen endotracheal tubes. The use of the Arndt bronchial blocker (ABB) as originally described is limited by the relationship between the diameters of endotracheal tube (ET), the ABB, and fiber bronchoscope (FBC) that should both pass through the indwelling ET. If a smaller ET is required or a 2-mm FBC is not available, the ABB must be placed alongside the ET. In this situation, a less than 3.5-mmdiameter FBC must be used to guide the ABB to the right position. We describe the use of a 3-mm-diameter choledochoscope for the placement of an ABB next to a 3.5-mm ET in a 5-month-old patient, requiring thoracoscopic resection of a giant bronchogenic cyst. Single-lung ventilation (SLV) allows a quiet and deflated surgical field. It also avoids the use of CO2 insufflation, which makes hemodynamic and ventilatory management easier. Unfortunately, SLV in children has been limited by the lack of small double lumen endotracheal tubes. On the other hand, the use of the Arndt bronchial blocker (ABB) as originally described is limited by the relationship between the diameters of endotracheal tube (ET), the ABB, and fiber bronchoscope (FBC) that should both pass through the indwelling ET. Considering that the diameter of the ABB at the tip is 2.5 mm and the smallest FBC available has an external diameter of 2 mm, a 4.5 ET is the smallest ET in which the ABB could be placed as originally described. Schmidt reported that a 4-mm internal diameter ET could be used if certain modifications were made to it (1). However, if a smaller ET is required or a 2-mm FBC is not available, the ABB must be placed alongside the ET. In this situation, a less than 3.5-mm-diameter FBC must be used to guide the ABB to the right position. We were recently challenged with the resection of a giant bronchogenic cyst in a 5-month-old patient. She weighed 7.5 kg and the procedure planned was a video thoracoscopy and resection of this cyst that occupied approximately half of the left hemithorax. Inhalation induction with sevoflurane was performed, followed by the administration of 0.1 mgÆkg of vecuronium and 3 ugÆkg of fentanyl. First, the ABB was placed and then, alongside it, a 3.5-mm uncuffed ET. Next, the ABB’s multiport adapter was placed on the ET, allowing for ventilation during fiber bronchoscopy. As a 2-mm FBC was not available, we used a 3-mm-diameter Olympus CHF type CB30 L choledochoscope (Figure 1) to guide the ABB to the desired (left) bronchus. Unlike the right bronchus, the left bronchus requires some additional maneuvers for correct positioning of the ABB. In our experience, rotating the patients’ head to the right while advancing the ABB and turning it counterclockwise, as described for blind selective intubation of the left bronchus (2), has been very useful to achieve this. In this patient, it was easily obtained at the second attempt. The balloon on the ABB tip was inflated with the minimum amount of air that provided adequate occlusion of the left main bronchus. This was confirmed by auscultation and later by direct visualization of the collapsed left lung. During the surgical procedure, oxygen saturation was maintained above 95% with a FIO2 of 0.5. The patient was extubated at the end of the procedure and sent home after 2 days. The case reported shows an alternative to the use of a very thin FBC when it is not available. As the choledochoscope is used only for visual guidance to the placement of the ABB, it does not need to be

Intramucosal gastric pH during liver transplantation

Intramucosal gastric pH (pHi) was measured during liver transplantation in a 3‐year‐old girl. The basal value was below that reported as normal for paediatric patients under stable normal ventilatory and haemodynamic conditions. Additional reductions of the pHi were observed during the hepatectomy and anhepatic phase, in the absence of haemodynamic or ventilatory alterations. The reperfusion phase was characterized by a progressive return toward normal values. Because we did not measure oxygen delivery and consumption, we cannot determine whether the reduction of the pHi was due to insufficient oxygen delivery or a result of the vascular anatomical alterations due to the surgical procedure.