Tidal Volume Lowering by Instrumental Dead Space Reduction in Brain-Injured ARDS Patients: Effects on Respiratory Mechanics, Gas Exchange, and Cerebral Hemodynamics.

BACKGROUND: Limiting tidal volume (VT), plateau pressure, and driving pressure is essential during the acute respiratory distress syndrome (ARDS), but may be challenging when brain injury coexists due to the risk of hypercapnia. Because lowering dead space enhances CO2 clearance, we conducted a study to determine whether and to what extent replacing heat and moisture exchangers (HME) with heated humidifiers (HH) facilitate safe VT lowering in brain-injured patients with ARDS. METHODS: Brain-injured patients (head trauma or spontaneous cerebral hemorrhage with Glasgow Coma Scale at admission < 9) with mild and moderate ARDS received three ventilatory strategies in a sequential order during continuous paralysis: (1) HME with VT to obtain a PaCO2 within 30-35 mmHg (HME1); (2) HH with VT titrated to obtain the same PaCO2 (HH); and (3) HME1 settings resumed (HME2). Arterial blood gases, static and quasi-static respiratory mechanics, alveolar recruitment by multiple pressure-volume curves, intracranial pressure, cerebral perfusion pressure, mean arterial pressure, and mean flow velocity in the middle cerebral artery by transcranial Doppler were recorded. Dead space was measured and partitioned by volumetric capnography. RESULTS: Eighteen brain-injured patients were studied: 7 (39%) had mild and 11 (61%) had moderate ARDS. At inclusion, median [interquartile range] PaO2/FiO2 was 173 [146-213] and median PEEP was 8 cmH2O [5-9]. HH allowed to reduce VT by 120 ml [95% CI: 98-144], VT/kg predicted body weight by 1.8 ml/kg [95% CI: 1.5-2.1], plateau pressure and driving pressure by 3.7 cmH2O [2.9-4.3], without affecting PaCO2, alveolar recruitment, and oxygenation. This was permitted by lower airway (- 84 ml [95% CI: - 79 to - 89]) and total dead space (- 86 ml [95% CI: - 73 to - 98]). Sixteen patients (89%) showed driving pressure equal or lower than 14 cmH2O while on HH, as compared to 7 (39%) and 8 (44%) during HME1 and HME2 (p < 0.001). No changes in mean arterial pressure, cerebral perfusion pressure, intracranial pressure, and middle cerebral artery mean flow velocity were documented during HH. CONCLUSION: The dead space reduction provided by HH allows to safely reduce VT without modifying PaCO2 nor cerebral perfusion. This permits to provide a wider proportion of brain-injured ARDS patients with less injurious ventilation.

Lung ultrasound to monitor the development of pulmonary atelectasis in gynecologic oncologic surgery.

BACKGROUND: Atelectasis formation is considered the major cause of hypoxemia during general anesthesia (GA). Gynecologic oncologic surgery (GOS) often requires pneumoperitoneum and steep bed angulation that further reduce lung compliance by shifting bowels and diaphragm. The aim of our study was to assess the impact of intraoperative variables on lung aeration using lung ultrasound (LUS) score and their correlation with postoperative oxygenation in women undergoing GOS. METHODS: In this prospective observational study 80 patients scheduled for GOS were enrolled. After three minutes pre-oxygenation, propofol-sufentanil-sevoflurane GA and standard mechanical ventilation (MV) were administered (tidal volume of 8 mL/kg of predicted body weight, FiO2 40%, I:E ratio of 1:2 and PEEP 5 cm H2O). A 0-36 LUS score was calculated considering 12 pulmonary areas, and arterial blood gas analysis were performed before GA (T1) and in recovery room (T2). RESULTS: LUS score increased significantly between T1 (1.79±2.39) and T2 (11.08±4.40, ΔLUS=9.29±4.10, P<0.05), mostly in basal and posterior areas. Changes in LUS score correlated significantly with time of MV (r=0.246, P<0.05), cumulative time in TR position (r=0.321, P<0.05) and worsening in oxygenation (ΔPaO2/FiO2, r=-0.260, P<0.05). ΔLUS score significantly correlated with colloid infusion. The linear regression analysis showed that TR time can predict ΔLUS score (F1,78=8.97, P=0.004). No correlation was found with pneumoperitoneum, apnea time at induction and TR angle. CONCLUSIONS: Aeration loss after GOS detected using LUS correlates with TR time, MV time, colloid infusion and worsening in oxygenation.

Ultrasound-guided genitofemoral nerve block for inguinal hernia repair in the male adult: a randomized controlled pilot study.

BACKGROUND: Ultrasound-guided (USG) ilioinguinal/iliohypogastric nerve (II/IHN) block is a widely validated anesthetic technique for inguinal herniorrhaphy. As the spermatic cord, scrotum, and adjacent thigh receive sensory innervation from the genital branch of genitofemoral nerve (GFN), the addition of GFN block has been suggested to improve the quality of perioperative anesthesia and analgesia. The aim of this study is to compare GFN block plus II/IHN block with II/IHN block alone for intraoperative anesthesia and post-operative pain management. METHODS: We enrolled 80, ASA I-III, male adults scheduled for elective open herniorrhaphy. Patients were randomized to receive either USG II/IHN plus GFN block (Case Group) or USG II/IHN block alone (Control Group). The outcome measures were the assessment of postoperative VAS scores on coughing and the adequacy of anesthesia, measured with intraoperative requirement for extra local anesthetic (LA) infiltration and number of patients needing systemic sedation. RESULTS: The requirement of intraoperative additional doses of LA was significantly lower in the Case Group (median LA volume administered by the surgeon: 13.8±5.6 mL vs. 20.7±9.1 mL, P<0.05). Two patients in the Control Group needed systemic sedation. VAS scores at 15 minutes, 30 minutes, 1 hour, 2 hours, pre-discharge, and 24 hours were significantly lower in the Case Group (P<0.005). Four cases of femoral nerve block were reported, three in the Control Group, one in the Case Group (2.2% vs. 7.7%, P>0.05). CONCLUSIONS: The combination of GFN block and II/IHN block is associated with lower postoperative VAS scores and lower doses of intraoperative additional LA.

Utility of ultrasound-guided transversus abdominis plane block for day-case inguinal hernia repair.

BACKGROUND: The transversus abdominis plane (TAP) block is a regional anesthesia technique that effectively reduces the pain intensity and use of analgesia in abdominal surgery. The aim of this study was to determine the utility of the ultrasound-guided TAP block in improving the efficacy of the ultrasound-guided ilioinguinal/iliohypogastric nerve (IIN/IHN) block for intraoperative anesthesia and postoperative pain control in day-case inguinal hernia repair (IHR). METHODS: We conducted a descriptive study of patients undergoing elective primary unilateral open IHR. Fifty-nine patients were divided into two groups according to the anesthetic technique used: ultrasound-guided TAP block plus ultrasound-guided IIN/IHN block (TAP group) vs. ultrasound-guided IIN/IHN block alone (IIN/IHN group). The outcome measures were the adequacy of anesthesia during surgery and postoperative analgesia. RESULTS: Four patients (12.5%) in the TAP group and 10 patients (37.0%) in the IIN/IHN group experienced inadequate anesthesia and needed systemic sedation (P < 0.05). No significant differences in additional local anesthetic volume were found between the two groups. Patients in the TAP group reported lower pain scores at the end of surgery (0.4 ± 0.8 vs. 2.1 ± 2.5, P < 0.01), at 2 hours after surgery (0.8 ± 1.3 vs. 3.0 ± 2.2, P < 0.01), at discharge (1.4 ± 1.2 vs. 4.3 ± 2.2, P < 0.01), and at 24 hours (1.5 ± 1.1 vs. 4.5 ± 2.3, P < 0.01). CONCLUSIONS: The combination of the TAP and IIN/IHN blocks is associated with better intraoperative anesthesia and lower postoperative pain scores compared with the IIN/IHN block alone.

Ultrasound-guided "short" midline catheters for difficult venous access in the emergency department: a retrospective analysis.

BACKGROUND: Acutely ill patients admitted to the emergency department (ED) constantly require at least one fast and reliable peripheral intravenous (PIV) access. In many conditions (morbid obesity, underweight state, chronic diseases, intravenous drug abuse, adverse local conditions, etc.), PIV placement may be challenging. Ultrasound guidance is a useful tool for obtaining a peripheral intravenous access in the emergency department, particularly when superficial veins are difficult to identify by palpation and direct visualization, though standard peripheral intravenous cannulas are not ideal for this technique of insertion and may have limited duration. Long polyurethane catheters inserted with ultrasound guidance and direct Seldinger technique appear to have several advantages over short cannulas in terms of success of insertion and of duration. METHODS: A retrospective analysis was conducted on all the ultrasound-guided peripheral venous accesses obtained by insertion of long polyurethane catheters in patients admitted to the emergency department of our university hospital during 1 year. The main indication to the procedure was the urgent need of a peripheral venous access in patients with superficial veins difficult to palpate and/or visualize. All relevant data concerning the insertion and the maintenance of these peripheral lines were collected from the chart. RESULTS: Seventy-six patients were included in this review. The success rate of insertion was 100 %, with an average of 1.57 punctures per each successful cannulation. The mean time needed for the complete procedure was 9.5 min. In 73 % of patients, the catheter was used for more than 1 week; a minority of catheters were removed prematurely for end of use. No major infective or thrombotic complication was reported. CONCLUSIONS: In our experience, 8- to 10-cm-long polyurethane catheters may offer a fast and reliable peripheral venous access in the emergency department, if placed by ultrasound guidance and with the Seldinger technique. Further studies with prospective, randomized, and controlled design are warranted to confirm our results.

Echography in brain imaging in intensive care unit: State of the art.

Transcranial sonography (TCS) is an ultrasound-based imaging technique, which allows the identification of several structures within the brain parenchyma. In the past it has been applied for bedside assessment of different intracranial pathologies in children. Presently, TCS is also used on adult patients to diagnose intracranial space occupying lesions of various origins, intracranial hemorrhage, hydrocephalus, midline shift and neurodegenerative movement disorders, in both acute and chronic clinical settings. In comparison with conventional neuroimaging methods (such as computed tomography or magnetic resonance), TCS has the advantages of low costs, short investigation times, repeatability, and bedside availability. These noninvasive characteristics, together with the possibility of offering a continuous patient neuro-monitoring system, determine its applicability in the monitoring of multiple emergency and non-emergency settings. Currently, TCS is a still underestimated imaging modality that requires a wider diffusion and a qualified training process. In this review we focused on the main indications of TCS for the assessment of acute neurologic disorders in intensive care unit.

Racemic ketamine in adult head injury patients: use in endotracheal suctioning.

INTRODUCTION: Endotracheal suctioning (ETS) is essential for patient care in an ICU but may represent a cause of cerebral secondary injury. Ketamine has been historically contraindicated for its use in head injury patients, since an increase of intracranial pressure (ICP) was reported; nevertheless, its use was recently suggested in neurosurgical patients. In this prospective observational study we investigated the effect of ETS on ICP, cerebral perfusion pressure (CPP), jugular oxygen saturation (SjO2) and cerebral blood flow velocity (mVMCA) before and after the administration of ketamine. METHODS: In the control phase, ETS was performed on patients sedated with propofol and remifentanil in continuous infusion. If a cough was present, patients were assigned to the intervention phase, and 100 γ/kg/min of racemic ketamine for 10 minutes was added before ETS. RESULTS: In the control group ETS stimulated the cough reflex, with a median cough score of 2 (interquartile range (IQR) 1 to 2). Furthermore, it caused an increase in mean arterial pressure (MAP) (from 89.0 ± 11.6 to 96.4 ± 13.1 mmHg; P <0.001), ICP (from 11.0 ± 6.7 to 18.5 ± 8.9 mmHg; P <0.001), SjO2 (from 82.3 ± 7.5 to 89.1 ± 5.4; P = 0.01) and mVMCA (from 76.8 ± 20.4 to 90.2 ± 30.2 cm/sec; P = 0.04). CPP did not vary with ETS. In the intervention group, no significant variation of MAP, CPP, mVMCA, and SjO2 were observed in any step; after ETS, ICP increased if compared with baseline (15.1 ± 9.4 vs. 11.0 ± 6.4 mmHg; P <0.05). Cough score was significantly reduced in comparison with controls (P <0.0001). CONCLUSIONS: Ketamine did not induce any significant variation in cerebral and systemic parameters. After ETS, it maintained cerebral hemodynamics without changes in CPP, mVMCA and SjO2, and prevented cough reflex. Nevertheless, ketamine was not completely effective when used to control ICP increase after administration of 100 γ/kg/min for 10 minutes.

Aspects of thermoregulation physiology.

PURPOSE OF REVIEW: The review covers the main aspects of thermoregulation physiology and highlights the implications for therapeutic hypothermia trials. Prevention of shivering and other hypothermia side-effects is of key importance because controlling thermoregulatory responses may be essential for demonstrating neuro-protective properties of hypothermia in several pathologic conditions in which its role is still uncertain, such as in traumatic brain injury and stroke. RECENT FINDINGS: Several recommendations and clinical reviews have been produced in the past 2 years about the application and feasibility of therapeutic hypothermia. Many drugs have been tested in healthy volunteers and anaesthetized patients to abolish shivering but the best protocol for managing side-effects has not yet been defined. A possible strategy might be to simultaneously apply physical methods, such as skin warming, and combination drug therapy. Different drug protocols can be applied, depending on the nature of the care setting. SUMMARY: During moderate hypothermia treatment, conducted in an intensive care environment, shivering can be treated with sedatives, opioids (meperidine in particular), and α2-agonists, combined with active skin counter-warming. However, new randomized controlled clinical trials in intensive care patients are required to improve our knowledge regarding this treatment.