Cardiovascular Journal of Africa: Vol 33 No 3 (MAY/JUNE 2022)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 3, May/June 2022 AFRICA 105 lasting with the SAP block (more than 12 hours), followed by the PECS II block (8–12 hours) and then the ICNB (4–6 hours).7 While their use is relatively safe, we must be cognisant of their potential complications, which include infection, thoraco-acromial artery injury, haematoma, pneumothorax and intravenous injection with subsequent LA toxicity. Anterior cutaneous branches can be anaesthetised by injecting LA in the fascial planes of the anterior chest wall. The intercostal nerves run between the innermost and inner intercostal muscles. As they reach the most anterior part of the chest wall, they run between the transverse thoracic (deeper) and internal intercostal (superficial) muscles in the same plane as the internal mammary artery. They then pierce through the internal intercostal muscle and external intercostal membrane anteriorly to give medial and lateral cutaneous branches, innervating superficial tissues in the parasternal area. The target anterior branches of the intercostal nerves are from T2 to T6. An ultrasound-guided pecto-intercostal fascial (PIF) block was introduced as an adjunct to PECS blocks, providing analgesia to the anterior chest wall with an injection placed 2 cm lateral from the sternum between the pectoralis major and (internal) intercostal muscles (Fig. 5). With a transverse thoracic muscle plane (TTMP) block, the injection is performed between the internal intercostal and transverse thoracic muscles (Fig. 6). However, the transverse thoracic muscle is a very thin structure lying posterior to the sternum and can be difficult to visualise with ultrasound. The TTMP and PIF blocks are useful for patients undergoing median sternotomies and patients with anterior chest wall trauma.8,9 Potential complications include infection, haematoma, pneumothorax and internal mammary artery injury. The PIF, compared to the TTMP block, avoids the plane of the internal mammary artery. In a prospective, randomised study, 108 patients undergoing open cardiac surgery received either bilateral PIF blocks or nothing. The primary endpoint was postoperative pain, with secondary endpoints being analgesia consumption, time to extubation, the presence of ileus, intensive care unit (ICU) length of stay, insulin resistance and interleukin-6 (IL-6) levels. The PIF block group consumed less sufentanil and parecoxib than the control group. Compared to the PIF block group, the control group had higher numerical rating scale (NRS) pain scores at 24 hours after operation, both at rest and during coughing. The time to extubation, length of stay in ICU and length of hospital stay were significantly decreased in the PIF block group compared with the control group. The PIF block group had lower insulin, glucose, IL-6 and HOMA-IR levels than the control group at three days after surgery. This study demonstrates that bilateral PIF blocks provide effective analgesia and accelerate recovery in patients undergoing open cardiac surgery.10 In a prospective, double-blind, randomised study investigating TTMP blocks, Aydin et al.11 showed good efficacy and a reduction in opioid requirements. They investigated 48 adult patients having cardiac surgery with median sternotomy. Patients were randomly assigned to receive pre-operative ultrasoundguided TTMP block with either 20 ml of 0.25% bupivacaine or saline bilaterally. Postoperative analgesia was administered intravenously in the two groups four times a day with 1 000 mg of paracetamol and patient-controlled analgesia with fentanyl. They demonstrated a reduction in postoperative 24-hour opioid consumption (p < 0.001). Pain scores were significantly lower in the TTMP group compared with the control group up to 12 hours after surgery, both at rest and during active movement (p < 0.001). Compared with the TTMP group, the proportion of postoperative nausea and pruritus was statistically higher in the control group (p < 0.001). Interestingly, the median fentanyl use in the control group was 465 µg, while it was only 255 µg in the TTMP group. A recent prospective, randomised, placebo-controlled trial investigated by Khera et al.12 determined the effect of PIF block on postoperative opioid requirements, pain scores, lengths of ICU and hospital stays, as well as the incidence of postoperative delirium in cardiac surgical patients at a single tertiary centre. The study investigated 80 adult cardiac surgical patients (age > 18 years) requiring median sternotomy. Patients were randomly assigned to receive ultrasound-guided PIF block, with either 0.25% bupivacaine or placebo. On postoperative days zero and one, patients receiving PIF block with 0.25% bupivacaine showed a statistically significant reduction in visual analog scale (VAS) scores (4.8 ± 2.7 vs 5.1 ± 2.6; p < 0.001) and 48-hour cumulative opioid requirement. A low incidence of complications and an improvement in VAS pain scores suggested that PIF block can be performed safely in this population and it warrants additional studies.12 The erector spinae plane (ESP) block was initially described for the treatment of chronic thoracic neuropathic pain. It can be used for acute postoperative analgesia involving chest, thoracic, cardiac and abdominal surgeries. LA is injected ventral to the erector spine muscle along thoracic levels 5–9, within the costotransverse foramen region, providing analgesia to the ventral and dorsal rami of the spinal nerves. The erector spinae muscle is the main component of the paraspinal muscles that stabilise the torso, but there is also Fig. 5. Pecto-intercostal fascial block (PIF). Fig. 6. Transverse thoracic muscle plane block (TTMP).

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